Jul 222014
The Tsar Bomba's 35 mile high mushroom cloud, as seen from 100 miles away.

The Tsar Bomba’s 35 mile high mushroom cloud, as seen from 100 miles away.

An interesting new study predicts that a limited nuclear exchange between warring powers would result in a ‘nuclear winter’ scenario.

The study says this would create global famine, cooling, drought and massive increases in UV radiation (due to damage to the ozone layer), lasting some 20 years, and with between hundreds of millions and billions of people dying (the total population on the planet is about 7 billion).

The full study is available here, and there’s a more easily read paraphrase/summary of it here.

This scenario is based on a hypothetical possible war between India and Pakistan, and assumes each side fires 50 nuclear warheads at the other side (ie 100 total), and each of a moderate 15 kiloton yield.

On the face of it, this sounds apocalyptic.  On the other hand, we have major concerns about the underlying assumptions of this computer model, and our email to the study’s authors requesting clarification, which they quickly opened and read, has gone unanswered.  Just like the old computer adage ‘GIGO’ (Garbage In, Garbage Out), if the model’s assumptions are wrong, then its conclusions are also flawed.

It is interesting to look at the study and see where the assumptions may be invalid, and also to draw some lessons for preppers from its projections, whether valid or not.  Although we don’t believe a ‘limited’ 100 warhead exchange would have the apocalyptic results forecast, other events might bring about these effects and so it is helpful to understand what to expect and prepare for in such a case.

The study is based on what would happen if 5 Tg (Teragrams, the same as 5 million metric tons) of ‘black carbon‘ (a fancy way of saying smoke soot) was released into the atmosphere, and suggests this is a likely result from the detonation of 100 15 kiloton nuclear bombs.

We can’t comment on the validity of the model’s projections for the impact of 5 Tg of BC into the atmosphere, and will assume that the model is correct about this – although note that most climatological models are somewhat controversial as the ongoing debate over global warming indicates.  But we do have concerns about the suggestion that 100 typical nuclear explosions, such as might occur in a limited nuclear exchange between warring powers, would have this effect.  Let’s have a look at what we see to be flaws in the model’s underlying assumptions.

The Problems With This Study’s Underlying Assumptions

The first reason for doubting this is that in total 100 15 kiloton explosions would seem to total to about the same as a single 1.5 megaton explosion (there are reasons for and against suggesting that 100 15 kiloton explosions create either more or less effect than one single 1.5 megaton explosion).  Let’s put that in context, to appreciate how ‘trivial’ (on a global scale!) that actually is.

During the days of above ground nuclear testing by both Russia and the US, nuclear explosions of much greater than 1.5 megatons in magnitude were regularly detonated, with the largest ever nuclear explosion, the Russian Tsar Bomba, being estimated at between 50 – 58 megatons in destructive power.  Yes, this one single explosion was almost 40 times greater than the amount this study says would be sufficient to create a 20 year ‘nuclear winter’, but created almost no measurable impact on local, regional, or global climate at all.

So clearly there is more to consider than just the size of the explosions.  There are several other factors built-in to the study assumptions which the authors have not clarified.  Some are described in some of the supporting studies they are relying upon, others are not clear to us and regrettably the authors have chosen not to reply to our queries.

The first thing to appreciate is there is a huge difference between an air burst and a ground burst nuclear explosion.  A ground burst throws up a lot more material into the atmosphere than an airburst.  Most nuclear weapons are designed to be detonated as air burst rather than ground burst devices, because an air burst has a greater blast effect, destroying more buildings for a greater distance than a ground burst.

Ground bursts are only used to destroy ‘hardened’ targets such as missile silos.

We don’t know what the model assumes about air vs ground bursts.

There are two assumptions that are detailed, however.  The first is that all explosions occur over built up areas, meaning there is a lot of combustible material (ie buildings) within the blast radius, making for much larger fires and smoke and black carbon release.

The second assumption is that none of the explosions overlap with the locations of any of the other explosions, meaning that each explosion is assumed to have a complete fresh supply of material to destroy and set fire to.

In other words, these two assumptions create a maximum ‘worst case’ scenario to build upon.

How likely are these two assumptions?  We rate them as unlikely rather than likely.  Nuclear targets tend to first be military installations, secondarily industrial, and only as a very distant lowest priority do we see population concentrations targeted.  Of course, often the industrial and sometimes even the military targets overlap with population clusters, but equally, many times they do not.  Strategic military bases are not in the centers of large cities, they are in outlying areas, and tend to be sprawling over hundreds of acres with a low concentration of buildings and little combustible material.

Furthermore, it is standard military doctrine to have multiple warheads targeting each priority target so as to ensure that if one of the warheads is intercepted, or fails, or goes off target, the backup warheads will still destroy the target.  Alternatively, if attacking a large population concentration, it is still likely that multiple warheads would be set to have overlapping regions of destruction rather than being evenly spaced out such as happens when you use a cookie cutter to cut cookies out of a sheet of dough.  The problem with the cookie cutter model is that it leaves parts of the city unharmed entirely, and other parts with only moderate degrees of harm.  When designing an attack to create maximum harm, it is more common to have overlapping explosions.

Seven Possible Problems with the Study’s Assumptions

So, we see at least seven problems with the study’s underlying assumptions :

1.  No nuclear tests, including some up to 40 times the magnitude of this complete 100 warhead scenario, have resulted in any significant climate change at all.

2.  We suspect the model assumes the ‘worst case scenario’ for air vs ground bursts, a scenario which is unlikely to be reflected by actual ‘best practice’ military doctrine.

3.  We do not believe that all of the 100 explosions would be over high density population centers.  Many – maybe even most – would be over lower density militarily or industrially significant areas with much lower BC release as a result.

4.  We do not agree with the model assumption that there would be no overlap in blast effects and that each and every one of the 100 explosions would occur over high density buildings that had not yet been partially or even completely destroyed by preceding blasts.

5.  There might also be some significance in the study’s choice of India and Pakistan as a location.  These two countries are closer to the equator than most other potential future nuclear battlegrounds, meaning that there will likely be more efficient and rapid transportation of the BC from the northern hemisphere to the southern hemisphere than if the nuclear explosions occurred further away from the equator.  In other words, this is another aspect of the study that might overstate the global implications of a nuclear exchange.

6.  If we are to accept the opinion that current industrial activity is causing global warming and adverse climate effects (and we’re not saying we do!), the depressed effect on the global levels of industrial activity caused by the predicted enormous famine and associated probable social and economic collapse will result in the reduction of other manmade carbon emissions and may therefore provide some counter-balancing relief from the effects of the BC release and accelerate the earth’s recovery.  There is no sign of this being factored into the study model.

7.  It appears their model assumed that all the BC was shot up into the atmosphere in a concentrated area of either 50 or 100 nautical miles in radius.  This is unlikely to be the case – India in particular is an enormous country with many different potential targets for nuclear attack, meaning a more realistic model should have a series of much more diffuse and smaller BC sources.  We also suspect that the model anticipates all 100 explosions occurring more or less simultaneously, whereas in reality, there is likely to be some spread of time during which they occur – possibly only minutes, maybe hours or days.  We don’t know what impacts this would have on the model, but we guess it may slightly soften the outcomes.

Is 5 Million Tons of Black Carbon a Lot?

One more thing.  The study is talking about the release of 5 Tg of black carbon, or 5 million tonnes.  How does that compare to current annual black carbon emissions?

We did some research and found wildly varying figures – for example, on this page almost next to each other are two contradictory claims, one suggesting about 7.5 million tonnes a year are released from all sources at present, and the other claim saying that forest fires alone release between 40 – 250 million tonnes a year.

According to this page, forest fires represent about 40% of total black carbon emissions, so if forest fires contribute 40 – 250 million tons a year, that would suggest in total between 100 and 625 million tonnes are released each year.

The significant part of the 5 million ton release from the nuclear war is that most of it is propelled up very high into the atmosphere and stays there for some time, whereas much of the ‘normal’ black carbon doesn’t go so high and more quickly falls back to earth.

But, at the same time, we have to note that if total black carbon emissions each year are as much as 100 times more than the amount released by this hypothetical nuclear war, is 5 million tons actually a significant amount to consider?  The study also does not put this size release into any sort of contextual perspective.

Prepper Implications of the Study’s Projected Outcomes

So, we think we can confidently state that this hypothetical 100 nuclear bomb scenario is unlikely to release 5 Tg of black carbon, and therefore, a nuclear winter scenario is unlikely from this.

But, maybe a larger scale conflict between major nuclear powers could indeed cause the 5 Tg release, and even a more limited black carbon release will still cause some modification to the global climate.  We also asked the study authors if the effects were linearly proportional – ie a 2.5 Tg release having half the impact of their modelled 5 Tg release, but, yet again, they didn’t reply.

So, while we are dismissive of the study’s basis and assumptions, there are still some valid lessons to be learned for preppers if we simply ask ourselves ‘what if some type of event caused a massive climate change?’.

1.  We often think about the impacts of a nuclear exchange as being one that is an attack on American soil.  It is easy to understand how nuclear explosions close to us would have some direct effects, but harder to realize that nuclear weapons going off on the other side of the world can still impact on us here.  Clearly, the risk is more global than we might first think.  A war between two far away countries can still upset the climate, globally.  From this perspective, the studied model provides more cause for concern than relief, and should encourage us to realize why it is such a bad thing, for, eg, Iran to be allowed to continue down its steady path to becoming a nuclear power.

2.  A probable outcome will be less solar energy for our solar cells.  Although UV levels will rise, these are not efficiently used by solar cells (which are most sensitive to red light, ie the part of white light that is red).  So we should allow for this loss of solar energy and increase our solar arrays accordingly.

3.  The cooling effect and shortened growing season means that we should consider locations that currently have sufficient growing season as to still remain productive with a 10 – 40 day reduction in season length.

4.  Substantial increases in UV radiation levels mean preference should be given to growing UV-resistant crops.

5.  While temperature changes don’t directly threaten our society or its industrial base, the loss of food production does and will threaten much/most of society, particularly when famine starts to cause the death of substantial percentages of the population.  In addition to slower acting famine, there is reason to fear that as the black carbon falls from the sky, there will be a fast and massive rise in respiratory diseases and deaths.

6.  The effects of famine will likely be of greatest impact in third world countries.  Hopefully, in the US, urgent attempts at creating hothouses, hydroponics, and other ‘high tech’ solutions, and simply changing our food habits to waste less and eat less, and buying in more food from other countries (assuming it is still for sale) will cushion the impacts on US society.  If we reduced our food intact to a more appropriate level and if we cut down on waste, we’d instantly halve our food requirements, and if we shifted our food production to most effective yielding crops, we’d probably bring about a doubling in net food production.

7.  It seems we should plan for less rain and – in areas currently short of water – more drought.  Ensure your location has sufficient water access, even in adverse conditions that – worst case scenario – may see rivers dwindle in size and creeks dry up entirely.  Rainwater collection systems will become less effective, and underground water table levels will drop due to reduced rates of replenishment (and possibly accelerated rates of offtake due to increased reliance on wells).

8.  This scenario shows an immediate impact on crop production (depending of course on what time of year the nuclear exchange occurs) and lasting effects extending 25 years or more.  On the other hand, if there are massive population losses in the first few years, it might be possible that the smaller sized population could more quickly balance the reduced agricultural capabilities and allow for a faster return to an industrialized self-sustaining society.

9.  The model shows that global temperatures drop over a five-year period.  This means that maybe the result is less a sudden apocalyptic transition and more a gradual deterioration in weather.

10.  The  climate change effects seem generally more extreme, the further away from the equator you go, and less extreme closer to the equator.  Perhaps this argues in favor of establishing a retreat in a southern rather than northern part of the US.

11.  Damage to crop DNA from increased UV levels will be passed from generation to generation, probably getting worse each time.  It is prudent to have sufficient stocks of seed to enable you to used undamaged seed to restart your crops several times during the period of increased UV.

12.  Air-borne fine particulate black carbon is harmful to health.  It will be beneficial to have filtration systems in your retreats to filter out the particulate matter before air is circulated within the retreat.  HEPA type filters will address this need, and if you get washable ones, that will extend their life (which will probably be much shorter than anticipated due to the much greater concentration of black carbon in the air).  If you’re going outside, you might want to use a respirator to give you protection while outdoors too.

13.  Although also impacted, the southern hemisphere seems to not be as severely affected as the northern hemisphere.  Because this type of climate based calamity would take some days/weeks/months/years to fully develop, it would give you time to fly to your choice of southern locations and set up your retreat there.


Although this study suggests an apocalyptic outcome of a relatively minor nuclear war, we disagree.  We think that the study may possibly overstate the direct results of a 100 warhead nuclear exchange, and we further feel that the western world – and in particular the United States – may be able to adapt its food sourcing and consumption fast enough to minimize the widespread famine and death projected in the study.

On the other hand, the increase in harmful particulate matter in the air is something that you do need to be able to respond to.

Depending on the importance you attach to this type of sudden climate change risk, you may want to factor it in to your choice of retreat location (ie issues such as water sufficiency, growing season length, and perhaps more generally, closer to the south than the north of the country).

Oct 182013
A Topol-M ICBM parading through Moscow's Red Square.

A Topol-M ICBM parading through Moscow’s Red Square.

Chances are you can come up with a long list of things that might go wrong so as to cause TEOTWAWKI.  But do you have ‘computer mistake’ on your list of things to worry about?  If you don’t, you should.

This article concerns the little known events on 26 September 1983, when Russia’s (well, back then, it was the Soviet Union) early warning system reported multiple missiles, launched from the US, and headed towards its territories.  The early warning system further rated the probability that this was a real bona fide first strike attack on the USSR at its highest level of certainty.

The duty officer at the monitoring station was supposed to urgently telephone the country’s leadership in Moscow, and there was close to a certainty that the leadership (Yuri Andropov had recently taken over the General Secretary position from Leonid Brezhnev) would respond by ordering a reciprocal strike on the US, launching their own missiles before the incoming missiles could destroy them on the ground.

But the duty officer suspected that, no matter what the computers were telling him, the warning was false rather than real, and saw some inconsistencies in the raw data.  So he disobeyed his instructions and instead of calling the leadership to report an incoming missile strike as he was supposed to do, he reported a system malfunction to the people responsible for maintaining it.

As it turned out, he did the right thing.  But if he had followed orders, we’d have ended up with an inadvertent nuclear war that would have very likely destroyed most of the US, the USSR, and much of the rest of the world.

Details here.

Thirty years later, could such a thing still happen?  Unfortunately, the answer is ‘yes’.  Indeed, there is less time now for incoming information to be evaluated and cross-checked, and more of an urgent need to respond before any incoming strike takes out our own (or anyone else’s) arsenal.  Furthermore, increased computerization makes it harder to see the ‘raw data’, and we instead have to rely on the computerized, processed, interpretations.

So go ahead and add this to your already long list of potential life-changing events – and put it in the most extreme category, because it is something that could suddenly occur without any warning or any chance for us to transition from our normal lifestyles to our retreats.  Perhaps now is also a good time to read our series on radiation issues.

Jul 072013
The Midland WR300 and the WR-120B are excellent and affordable SAME equipped NWR EAS compatible radios.

The Midland WR300 and the WR-120B are excellent and affordable SAME equipped NWR EAS compatible radios.

We’ve written before about the need to urgently make your way to your shelter if you receive a warning of pending nuclear attack, and about setting a policy for how long you wait for others to join you in your shelter.

But these considerations overlook one vital issue.  How can you get any such warnings of any type of pending disaster that you need to respond to?  It isn’t just pending nuclear Armageddon you have to be worried about, either.  All sorts of weather related events, or other local emergencies – dangerous chemical spills, public safety/law enforcement alerts, and so on – might occur, and it would be advantageous to be among the first to know of such issues.

In scenarios where seconds may literally make a life and death difference to your ability to adequately respond to an urgent threat, you can’t rely on noticing an item on the television news or hearing a special announcement on a regular radio.  You need some type of specific warning system that will grab your attention directly if an urgent warning is issued.

The good news is that there is a national system in place for such warning messages to be promulgated, and it is tied in to the National Weather Service – the NOAA Weather Radio All Hazards (NWR) service.  You can get special radio receivers that will be activated by such warnings (see below for details).

These Emergency Alert System (EAS) emergency messages are sent out with additional data attached to them, specifying the type of alert message and the county it applies to.  Messages can be for a single county, for up to 31 different counties, for an entire state (or multiple states), or for the entire nation.  The geographic tagging of the message is referred to as Specific Area Message Encoding or SAME.

Alert messages fall into one of various different descriptive categories (ranging from Avalanche watch messages to volcano warnings) and have one of four different status codes signifying their degree of immediacy.  The four codes are :


  • A WARNING is an event that alone poses a significant threat to public safety and/or property, probability of occurrence and location is high, and the onset time is relatively short.
  • A WATCH meets the classification of a warning, but either the onset time, probability of occurrence, or location is uncertain.
  • An EMERGENCY is an event that, by itself, would not kill or injure or do property damage, but indirectly may cause other things to happen that result in a hazard. For example, a major power or telephone loss in a large city alone is not a direct hazard, but disruption to other critical services could create a variety of conditions that could directly threaten public safety.
  • A STATEMENT is a message containing follow-up information to a warning, watch, or emergency.

Emergency and Statement type messages are sometimes grouped together as ‘Advisory’ messages, making for a three level set of categories.

Here’s a list of different message types that might be sent as part of a NWR EAS message.

SAME/EAS Capable Radios

Clearly it makes sense to buy a specific radio designed to receive these types of messages.  The radio, while switched on, would normally be silent and would only come to life if it received a message coded to the county or counties that you wanted to receive alert messages for.

Ideally, you’d want the radio to be mains operated but with a battery backup capability so if the power goes out, the radio will still continue functioning.

You want to be able to program the radio as to which counties you wish to receive alert messages about.  We suggest you should program alerts for adjacent counties as well as your own county, especially if your county is small or you are close to the boundary with another county.

Some radios also allow you to filter out some types of alerts that you don’t want to be advised about – for example, if you live a long way from the coast, you might not be interested in coastal flood warnings, and you might decide to forego receiving child abduction messages no matter where you live.

And, of course, you want to be sure the radio has some type of loud warning device – an alarm or siren – that will sound when it receives a warning so you’ll be instantly notified.

noaaSome radios might be certified as complying with either the Public Alert Standard or as being approved by the NOAA as having the necessary capabilities for the system.  You can see the two logos displayed here.  Radios that are so certified might not be fully featured, and ones that have not paid for the certification may be equally featured or even better.  So these certifications are interesting, but not mandatory.

publicalertWhile some model radios can be expensive, you can also find excellent units for under $30 – for example, this Midland WR-120B which sells for about $25 at Amazon .  If you wanted to spend a bit more, the Midland WR-300 is also a good choice (about $45), but doesn’t have any additional ‘must have’ features compared to its cheaper cousin, the WR-120B.


All the preparations in the world will be useless if you’re not warned in time to respond to a sudden unexpected threat.

The NWR EAS system might send out warnings in time for you to respond to them, but only if you have a compatible radio receiver that will ‘switch on’ and alarm/alert you when it receives the specific types of warnings you have told it to respond to.

While the NWR EAS system isn’t guaranteed to always give you adequate notice of all pending threats, it certainly increases your odds of being alerted in time to adequately respond.  With compatible radios costing as little as $25, it is something you should invest in.

Jul 012013
This shelter/bunker has easy access and would allow people to quickly make their way to safety.

This shelter/bunker has easy access and would allow people to quickly make their way to safety.

If you have a shelter and are unfortunately in a region where there’s a danger of being caught by the initial immediate effects of a nuclear explosion, then of course you must get into the shelter and have it secured, shut, prior to any bombs being detonated.

Assuming you even get any warning about an imminent attack (and that’s a very big assumption which we evaluate in a separate article), you almost certainly won’t know how long it will be from when you receive the warning to when the warheads might arrive and explode above you.  In another article, we calculate that the very best case scenario might see you with a five minute warning, maximum; and the more likely scenarios have warnings being too late and not being sent out (and/or not being received by you) until after the missiles have arrived.

So you truly are in a situation where seconds count.  Best case scenario, you have no more than 300 seconds (ie five minutes) from the start of a warning message until the explosion.  More likely, you may have only one or two minutes to get into your shelter.

It goes without saying that of course you want for you and as many other members of your group as are presently close to your shelter, to get into it and have it secured prior to the bomb(s) going off.  Read on for some thoughts about how to make this as achievable as possible.

With most retreat/shelter layouts, you should be able to get to your shelter and inside it in less than 60 seconds (depends how quickly you can get its door open and closed, of course).  Some people might be closer and able to do so in under 30 seconds.  Others may be more distant (we talk about that a bit further on).

You and everyone else must, the instant you get a warning, stop anything/everything you are doing and move immediately to the shelter, because you have no way of knowing if the warning you have received leaves you with 10 seconds or 10 minutes of time before the bombs start exploding around you.

Warning/Alerting Others in Your Group

The only thing you need to do, prior to rushing to your shelter as urgently as possible, is to warn the other people in your group and summon them to the shelter.  We suggest the best way to do this is not by calling out to them, but by sounding a (very loud) audible alarm.

Do not use a method that puts the responsibility on you to make sure other people have heard and understood the alarm.  And do not use some type of alarm system that will delay your own rush to the shelter.  All you should have to do is flip a switch somewhere close by on your likely route to the shelter.

Use some type of general alarm and make sure it is clearly understood that there will be no checking up, so when the alarm goes off, it is everyone’s personal responsibility to hear it, recognize it, respond to it, and get to the shelter before it closes, without assistance.  Sadly, we as a nation have largely turned out back on the concept of personal responsibility, so this may require a paradigm shift, and some passive aggressive responses from some of your group who are slowest to accept this concept (you may uncover this when you do rehearsals – see below).

The only exception to personal responsibility would be, of course, for people who genuinely truly do need assistance.  The aged, infirm, and the very young.

Perhaps the best alarm system would be to have a series of sirens or alarm bells installed around your residence, connected up to a car battery that is being trickle charged by a standby battery charger.  These would be all activated by any one of a series of switches around the house, all in parallel, so that turning any one of them on will activate all the alarms.  The battery/mains power source means that if there’s a power cut, your alarm system will still remain functional, potentially for days or weeks until the power is restored (the alarm system will not be drawing appreciable power until it is activated).

With multiple alarm devices, you can locate them wherever people may be and wherever distracting noises may be present.

If this is too complicated, then a simple system could be to use warning horns that run off cans of compressed air, and have those in multiple locations in your house on the route to your shelter.  Have them in a cradle with a lever so that you can pull the lever down to actuate the device and have it stay actuated for however long there is air in the can.  You can just quickly flip it on and then continue on your way to the shelter.

Failing that, even simple whistles that you can blow, in several places around the house, might be a suitable alternate way of providing a loud can’t be missed urgent alarm sound, but if you’re blowing a whistle as hard as you can, you’re going to be slowing yourself down on your own rush to the shelter.

You’ll be able to test this of course and get a feeling for how clearly a whistle or air horn can be heard in the furthest away nooks and crannies of your residence and the grounds immediately outside.  Probably you’ll find it necessary to use an electric siren system with multiple sirens – these are easy to design and construct.

Note that the human ear will detect an intermittent sound better than a steady sound.  So instead of one long blast of the air horn, or one huge blow of the whistle, you want repeated multiple short blasts.  Each sound should be at least half a second in duration.  Electronic siren devices with programmable siren tones might be better, from this perspective, than steadily sounding alarm bells.

Three final suggestions about this.

First, make sure the alarm sound is very different to other alarms and warnings and sounds in and around your house.  You don’t want it to be confused with your alarm clock, the timer on the microwave, a carbon monoxide detector, a smoke detector, the neighbor’s burglar alarm, your car alarm, etc.

Second, don’t make the alarms ridiculously deafeningly loud, and don’t choose a siren sound pattern that is disorienting (fast warbles are particularly disorienting).  You want to alert people, not disorient and confuse them.

Third, have an alarm cut-off switch in your shelter, so that when you close up your shelter, you can turn off the alarms.  This does two things.  First, it gets rid of the noise in the background that might otherwise continue for many hours.  Secondly, people know that if/when the alert siren stops, that means the shelter has been closed and they should make other emergency arrangements for shelter.

Whatever method of warning other people in and around your house you choose, of course you must test it to ensure that everyone can hear it, everywhere in the house, no matter what they’re doing.  The person singing in the shower, the person with headphones on listening to their iPod, the person laughing and giggling with friends, the person watching a loud movie, the heavy sleeper in their far away bedroom, the person mowing the lawn outside and so on – all of them must be absolutely able to clearly hear the alarm.

Map Out Travel Times to the Shelter

The next part of your planning is to understand how long it will take people to get to the shelter from different parts of your residence and adjoining property.

You want to do test drills from various locations so you build up an understanding of what the range of times will be to take people to get to your shelter.  Time both faster/nimbler members of your group and slower/less dextrous members too, so as to get best and worst case scenarios.

As you do this, you’ll quickly see that, for example, people can get from everywhere in your house to the shelter in a maximum of (whatever number) seconds, and where the furthest away (from a traveling time point of view) locations are.

If you have some people who are less agile on stairs or whatever, of course their travel times will prove to be significantly different if there are stairs or other complicating factors.

Please understand, at this point, that mapping out the times is not the same as setting a policy for how long you’ll wait for people to get to the shelter, but it certainly is the step prior to that and provides you with helpful data to consider when making those difficult decisions, discussed in the next article.

There’s also one other thing to consider when looking at time it takes to get to the shelter.  The key issue is how much more time it will take people from further away to get to the shelter than it will take people close by.  That is the most difficult time, when some people are already in the shelter and waiting anxiously for the door to be closed and for safety to envelop them.

Rehearsing Shelter Alerts

You need to carry out rehearsal drills to instill the appropriate instincts in everyone in your group to move to your shelter instantly and also to check for things like the ability for your alert/warning sound to be heard.

Do we need to tell you that once an alarm is sounded, don’t pause to grab anything (because everything you need for an extended stay in the shelter must be already pre-positioned in the shelter), don’t fuss over opening/closing doors/windows, don’t turn anything on or off, just go directly to your shelter.  Nothing else matters, because you’re anticipating a scenario where everything outside the shelter is about to be completely destroyed, after all!

Some rehearsals can be simple timed exercises to see how long it takes each person to get to the shelter, and see what issues each person experienced in terms of delays and problems, then work on fixes to optimize those issues.

Depending on the type of entrance to your shelter, you might also discover problems having a number of people all transit through it at once.  If that is the case, see which way works best – slow people first, fast people second, or vice versa, and see if there’s a way for more able-bodied people to assist the less able-bodied people.

If you have a vertical shaft with a ladder leading down into a shelter, maybe there’s a way you could augment that with a ‘fireman’s pole’ on the other side of the shaft, opposite the ladder?  That way some people could use the pole to quickly go down while others use the ladder.

We suggest you never have a total surprise alert, because the adrenalin caused by an unexpected and apparently for real alert might prove too much for the weaker hearted among you.  But it would be acceptable to say ‘Some time today or tomorrow I’ll sound the alarm’ – there’s no need to have everyone ready, waiting, and already prepared.

Now for an important thing.  After a few ‘normal’ rehearsals, you want to then start adding a new element into the practicing.  You want to deliberately be late, yourself, and subsequently secretly arrange with other individuals for them to be late.  You are now rehearsing not just the ‘getting to the shelter in time’ scenario but also the ‘closing the door in the face of late-comers’ scenario, and this is an essential thing to rehearse.  Not only does it give the door closer the confidence to do so, but it also impresses on the stragglers that the door will close at the agreed upon time (see our separate article on how to set these policies).

A Policy For Unexpected Guests

What say you have friends visiting when an alarm is sounded.  What do you do – leave them staring in amazement as you suddenly all get up, open a hitherto unseen ‘secret panel’ in the wall behind them, and rush down a flight of stairs without a word of explanation?  Or try to hastily tell them what is happening and invite them in to your shelter with you?

On the basis of safety in numbers, and on the basis of it is probably easier to include them than to exclude them, you probably should plan your shelter to have some extra capacity – extra space, extra beds, extra food, and so on.  So, in the event an alarm should occur when you have guests visiting, and all other things being equal, you invite them too.

This assumes that the visitors are people who you are generally compatible with and who truly would add to the overall dynamics and resilience of your group.  The problem is that your group will have had time to already prepare their attitudes and mindset to the scenario that is now unfolding, and hopefully have some fortitude with which to face the future.  Non-prepping friends might bring with them all the dysfunctional attitudes and expectations that have made our society as unstable as it presently is.  Which would be worse?  To exclude them from entry to your shelter at the get-go (quite possibly at gunpoint) or to eject them from the shelter some days later (again quite possibly at gunpoint)?


All your investment in a shelter is wasted if you and the rest of your family/group can’t get there in time, before any bombs start to go off around you.

You need to plan and then practice the process of making your way to your shelter as quickly as possible, because if an alert is ever sounded, you may have mere seconds to get from wherever you are to the safety of your shelter.

Jul 012013
A nice shelter entrance, designed so blast waves will be partially deflected off the door.

A nice shelter entrance, designed so blast waves will be partially deflected off the door.

So you have invested in a blast/radiation shelter, and done all the necessary things to stock it and prepare for an emergency.  And then, one day, an emergency truly occurs.  You all (presumably) rush to the shelter, but inevitably, some of you get there before others of your group or family.

How long do you keep the shelter door open, waiting for the slower and slowest people to get there?

This is probably the most difficult consideration for you to grapple with.  How long do you keep the shelter open (and thereby imperiling everyone already inside it) while you want for the slowest (or furthest away) members of your group to reach it?   For example, what do you do if you have four family members in/around the house, and when the warning sounds, two of you are able to get to the shelter within 30 seconds, the third is somewhere that will take a minute, and the fourth is two minutes away.  Do you wait the extra minute and a half for the fourth person to arrive, or do you shut and lock the shelter after the third person?  For that matter, do you even wait for the third person?

Another way of looking at it is should the three of you who have made it to the shelter now risk your safety by leaving the shelter open for the fourth person to join you?  Remember, you have no way of knowing if there’ll be an explosion in your area in 5 seconds, 5 minutes, 5 hours, or maybe not at all.

There are a couple of ways you could create a policy to cover this situation, and probably the first thing to do would be to understand the likely ‘worst case scenario’ times it would take people who are outside the house, but close to it, to get from where they are to the shelter.  If our next article we talk about, amongst other things, creating a type of time/distance map so everyone knows how long it will take to get to the shelter from wherever they are when the alarm is sounded.

This can also help people to understand, based on their location, if they will be able to get to the shelter or not.  If they know in advance they are out of range, they can consider alternate temporary shelter arrangements and then go the rest of the way to the main shelter subsequently.

A Recommended Solution to This Problem

The best approach to allowing stragglers to be admitted without risking the people who arrived in plenty of time is to consider an ‘airlock’ sort of design for the main entrance to your shelter.  This will allow a person in through the outer-most door into an intermediate chamber.  After they have closed the outer-most door, you open the inner door and allow them the rest of the way in.  This would be a suitable solution that allows additional people in to your shelter safely, while not requiring the people who have already reached the shelter to compromise their own safety in the process.

If you do this, we recommend you have some simple mechanical interlocks that will make it impossible for both doors to be open simultaneously.  That way there can’t be any ‘cheating’ or mistakes that cause both doors to be open, risking everyone inside if a blast occurs during this vulnerable period.

The ‘air lock’ section should be large enough for several people to easily be in it at a time, so as not to slow down the process too much for everyone.

This type of approach will also be helpful when you start venturing out of the shelter during the period of time after the bombing has ended, but while you need to stay in the shelter for protection against dangerous nearby radioactivity.  The ‘airlock’ design (with the two doors offset so that if both doors were open at the same time, it would not be possible to see from the shelter, through both doors, and to the outside) and augmented with a decontamination facility in the airlock passage would allow people to go in and out without allowing radiation or fallout contamination to enter.

As a much less desirable alternative, and depending on the type of shelter design, maybe it is possible to quickly reopen and reclose the door again to let other people in – that way the door would only briefly open for a few seconds for another person or two to quickly come in, then the door would close again.  If you have some baffles protecting the door so that, even if the door were fully open, there would be no direct radiation or heat path from a possible explosion point to inside your shelter, and the force of the blast wave would be dissipated, that would help reduce that risk, but of course, there’s a tremendous and potentially fatal difference, particularly if you’re within the radius of the initial fireball, as between having your door even slightly open and securely shut.

Our preference and recommendation is for an ‘airlock’ type approach – this will also be useful when people venture out and return during any subsequent period of dangerous outside radioactivity.

Have a Formal Policy that Determines When You Shut Your Shelter Door

If you don’t end up with an ‘airlock’ type arrangement, then you need a policy for when the door will be shut and locked.  Whatever you settle on, you first need to fully discuss and then mutually agree on it, and then, put it in writing so that there is no misunderstanding and everyone knows what to do and when to close the door.  That way, there are no feelings of guilt or blame attached, either for people who get there in time or for those who might not.

A formal policy also means that people who know they won’t be able to make it to the shelter will know that up front, and instead of wasting valuable time unsuccessfully getting to the shelter, can immediately work on whatever alternate option might exist.

The first possible formal policy approach would be to say that you will wait for everyone to arrive.  That’s for sure one approach, although it then ties the fate of all of you to the actions of the slowest of you, and also removes the pressure on the slowest person to be as ultimately fast as they can be, because they know you’ll wait for them.  It is probably the worst policy to consider, so while we mention it, we don’t recommend it.

A second policy would be to say that the first person to the shelter starts a timer with a pre-agreed upon time period.  When the timer finishes, the shelter door closes, no matter who or how many of you are still out there.  You could decide if that timer would be for 30 seconds, a minute, or however long you feel necessary.

A related approach is for the activation of the alarm to also activate a timer, and when the alarm has been sounding for a specified time, as agreed in advance and shown on the timer, whoever is in the shelter will then close it, no matter who is not yet there.

The third approach would be to say that if there are, eg, four of you in your group in total, then the shelter will stay open for so many seconds after the second or third of you arrive.

A fourth approach would be, and let’s again say there are four of you, then you say that when the third person gets into the shelter, if the fourth person isn’t in sight of the shelter door and within a couple of seconds of entering, the door will shut.  Of course, you can set a policy so it isn’t just the second to last person who triggers the conditional door closing, you could decide that ‘the majority rules’ and as soon as half your group have reached the shelter, then there is only a very few seconds before the door closes.

There are many other ways you could agree on when the door will be closed.

Our own preference would be to set a timer based on either from the start of the alarm signal or when the very first or second person arrives.  If you wait until most of your group has arrived, there’s a danger that some people will say ‘don’t worry, we’ll wait for you, Bill, and with all three of us not yet there, they won’t close the door’.  But if you make it so the first or second person activates the timer, and that the door should close at the end of that time period, no matter who or how many people remain outside, then there can’t be any ‘collusion’ and everyone will be headed as fast as they can to the shelter.

One more thing.  When the time to close the door is reached, you must then close the door, no matter if there is someone only seconds away.  Because if you delay for that person, then maybe when they have got in, there will then be another person coming into view, also only seconds away.  So you delay a second time, and now you’ve added however longer of risk with the door open to the entire group inside the shelter.  When the time to close is reached, the door shuts, even if it slams shut in the face of someone within inches of reaching it.

Your group also needs to understand that this is all about the survival of the fittest and the most committed, which will be the way of the new world.  The person in charge of closing the door needs to give most priority to protecting the well-being of those people who did get to the shelter in the agreed upon time.  It is not appropriate to risk the safety of all who did comply in the possibly futile hope of allowing non-compliant group members to get to the shelter too.

We also urge you to use a timer, because that makes it an impersonal decision.  As soon as the timer signals the end of the timing period, the door must be closed.  It is no-one’s fault, and no individual’s personal mean-minded decision to close the door in the face of people rushing towards the shelter.  It was a group decision to set the process the way it has been set, and a group responsibility to now honor the arrangement agreed.

Temporary Shelters

Your main shelter will be equipped for you to live there for a month, ideally for longer.  But if you don’t have an airlock system to allow people to come in at any time, and if you have a significant probability that some people won’t be able to make it to the main shelter before you close and lock the entrance, perhaps you might need to consider a temporary shelter that would be suitable for protection from the initial blast effects only, and in which people could stay in briefly and then make their way the rest of the way to the main shelter as soon as it was safe.

There will be a window of safety between when the bombs have stopped exploding and when the fallout starts to come down where there’ll be little radioactivity outside, making it safe for people to quickly move from a temporary shelter to the main shelter.  That will only be for 30 minutes or so, however, so in such a case, we’d suggest timing from the first blast, waiting maybe 20 minutes or so (in case of additional bombs), then rushing from the temporary shelter to the main shelter.


We recommend you design your shelter with an ‘airlock’ type entry so as to allow for people to safely enter the shelter even as a blast is occurring nearby.  This avoids the ugly issue which you’d otherwise need to consider and plan for – what to do with stragglers when you’re all rushing to your shelter.

If you don’t have this type of airlock, you need to agree that it is not fair that everyone else in your group is put at risk while the shelter remains open and vulnerable due to some people being slow to get to the shelter.  You need to be prepared to close and lock the door after an agreed upon time period, no matter who remains outside.

Jun 272013
The effects of the bomb at Hiroshima were greatly magnified by the flimsy construction methods used in the city.  The few buildings constructed to western standards proved comparatively robust.

The effects of the bomb at Hiroshima were greatly magnified by the flimsy construction methods used in the city. The few buildings constructed to western standards proved comparatively robust.

This is the first part of a two-part article about surviving nuclear blasts.  In this first part, we look at the immediate effects of nuclear blasts, in the second part, we will look at longer term effects.

Few things are more horrific in many people’s minds than the thought of being close to a nuclear explosion.  Some people have gone to great lengths, constructing massive bunkers/shelters in their basements, to do what they believe may be necessary to optimize their chances of survival in such cases.  But – two questions :  Are such things really necessary?  And, if they are necessary, will they truly protect you?

Sure, we agree that ground zero would not be a nice place to be at, but the horror and the power of nuclear weapons are often overstated and misunderstood – especially by the ‘anti-nuke’ campaigners; oh yes, and by bunker salesmen, too!  So, let’s first investigate the question – how survivable is a nuclear explosion, and then in a subsequent article series we’ll evaluate the best type of bunker or other shelter structure that would be appropriate for most of us.

The survivability of a nuclear blast depends on several variables (of course).  In particular, it depends on how powerful the nuclear bomb is – and that’s the first variable most civilians fail to account for.  A second variable is how far you are likely to be from the blast (and we consider some of the surprising unexpected considerations related to determining that in the second part of this two-part article).

Other variables include the weather (obviously wind has a massive impact on fallout patterns, so too does rain), the time of day (the nuclear flash will blind more people at night), topography (you might be sheltered by a hill) and ‘urban clutter’ (buildings and other things that occlude and slow down a blast wave more quickly than most theoretical models allow for).

One more huge variable is whether the blast is an air blast (most likely), a surface blast (less blast effect but massively more fallout) or a sub-surface blast (effects depend on how deep the blast is).

How Powerful Are Nuclear Weapons?

Nuclear bombs are measured in terms of the equivalent amount of TNT required to create a similar blast.  Actually, due to various imprecisions, these days they are measured in terms of total energy released which is converted to a theoretical equivalent amount of TNT to make it sound more scary and also more meaningful – if you were told that a bomb had a power of 4.184 petajoules you’d have no idea what that meant, but most people can vaguely comprehend that a one megaton bomb is awesomely powerful.

The 1 MT rating is equivalent to the 4.184 petajoule rating.  You might not be familiar with the ‘peta’ prefix – a petajoule is  1000 terajoules, or 1,000,000 gigajoules or 1,000,000,000 megajoules, or, in the ultimate, 1,000,000,000,000,000 joules – a very big number indeed!

But, back to the usual common measurement of nuclear weapons.  The power of such weapons is usually measured either in kilotons (kT) or megatons (MT), being respectively 1000 tons or 1,000,000 tons of TNT equivalent.

Nuclear bombs range in size from a few kilotons of TNT equivalent power to possibly over 100 megatons of TNT equivalent power.  The smallest that we are more or less aware of were the (withdrawn from inventory more than 30 years ago) W54 series of warheads, with explosive blasts measured in the mere tons or tens of tons of TNT equivalent.

The biggest ever exploded was a Russian bomb, called  the Tsar Bomba, which created an estimated 57 megaton blast, in 1961.

To put these sizes into context, conventional ‘high explosive’ type bombs range from some tens of pounds of TNT equivalent up to the largest GBU-43/B bombs with an 11 ton yield.  Russia might have an even larger bomb with a 44 ton yield.  Most conventional bombs have an under half ton yield.

So that’s the first take-away point.  A ‘nuclear bomb’ can range from something less powerful than a conventional technology bomb, to something of hard to comprehend power and magnitude.

There’s as much as a million times difference in power between a small nuclear bomb and a huge one – that’s like comparing the tiniest firework cracker with a huge 6000 lb conventional ‘bunker buster’ bomb.  Except that, of course, even the smallest nuclear weapon is sort of like a huge 6,000 lb conventional bunker buster bomb, and they just go up from there in scale!

Nuclear Bombs Are Getting Smaller

A related piece of good news.  Although the first decade or two of nuclear bomb development saw a steady increase in size/power, that trend has now reversed.  The two bombs used against Japan were approximately 13 – 18 kT for the Hiroshima bomb and 20 – 22 kT for the Nagasaki bomb; and then for the next fifteen years or so after that, bomb sizes got bigger and bigger.

The largest bombs ever tested were the US Castle Bravo test in 1954 (15 MT – this was actually a mistake, it was planned to be only half that size) and the Russian Tsar Bomba test in 1961 (57 MT).

Since that time, the typical warhead size has gone down again rather than up.  Happily, bigger is not necessarily ‘better’ when it comes to nuclear weapons.  There are several reasons for this.

Due to the increased accuracy of the delivery systems, there has become less need for a massively powerful bomb – a smaller bomb delivered with precision would generally have the same or better effect than a bigger bomb that arrives some distance off target.  Earlier missiles were only accurate to within a mile or so of their target, the latest generation are thought to be accurate to 200 ft or so, so there is no longer a need to have a weapon so powerful that it will be capable of destroying its target, even if it is a mile further away than expected.

Secondly, the evolution of multi-warheaded missiles means that instead of a missile delivering one big bomb to one target, they can now deliver two, three, or many bombs to many different targets, but this requires each warhead to be smaller and lighter (ie less powerful) than otherwise would be the case.

With a single missile having a limited amount of space available and weight carrying capability to transport warheads, and with a fairly direct relationship between a bomb’s power and its weight (and lesserly space), there has been a general favoring to the smaller warheads, although Russia still has a few enormous 20 MT warheads in its inventory.

There is also the surprising and counter-intuitive fact that the effects of a nuclear explosion do not increase directly with the increase in its power – that is to say, a bomb with twice the rated TNT equivalent explosive power does not also have twice as much destructive power; it has more like perhaps 1.6 times the destructive power (the actual relationship is x0.67).

This means it is better to have two bombs, each of half the power of a single bomb (and better still to have four bombs, each of one-quarter the power).  In terms of maximizing the total destroyed area, if you have a single missile that could have, say one 8 MT warhead, two 4 MT warheads, or four 2 MT warheads, generally this last option would be the most desirable one.  It also means the attacker can choose between sending multiple warheads to one target, or being able to attack more targets.

Furthermore, having four warheads all splitting off from the one missile gives the enemy four times as many objects to intercept.  It is much harder to safely defend against four incoming warheads than one.

So, for all these reasons, multiple small bombs are now usually the preferred approach.

Bigger Bombs Don’t Have Proportionally Greater Destructive Ranges

This statement needs explaining.  There are two factors at play here – the first is that if a bomb is eight times bigger than another bomb, it doesn’t destroy eight times as many square miles (due to the power of the bomb not increasing linearly with its TNT equivalent, as explained in the preceding section).  At the bottom of this page it says that eight small bombs might cover 160 sq miles of area (ie 20 sq miles each), whereas one single bomb, eight times the size, would only cover 80 sq miles.

The second factor is to do with the difference between a bomb’s destructive area and its destructive range.  A bomb’s destructive area spreads out more or less in a circular pattern, but the area of a circle is proportional to the square of its radius.  In other words, for a bomb to have a radius of destruction twice as far as another bomb, it would need to be four times more powerful, not two times as powerful.

So, continuing this example, 80 square miles require a circle with a radius of 5.0 miles, and a 20 sq mile circle has a radius of 2.5 miles.  In other words, to double the distance within which a bomb will destroy everything, and after allowing for both the square relationship between distance and area, and the less than doubling of explosive effect when you double the power of a bomb, you have to increase its explosive power not twice, not four times, but eight times.

This is presented visually in the following diagram, which shows the radius of the fireball created by bombs of different sizes, ranging from small to the largest ever detonated (sourced from this page).


Don’t go getting too complacent, though.  This is only the close-in fireball – the blast and temperature effects would extend much further than this (although subject to the same proportionality).

Actual Effects and Safe Distances

Now that we start to talk about actual damage and death, it is important to realize that these things are not clear-cut.  Apart from extremely close to a bomb’s detonation, where everyone will be killed, and everything destroyed, and extremely far from its detonation, where no-one will be killed and nothing destroyed, in the range between ‘very close’ and ‘safely far away’ there is a sliding scale of death and destruction.  There are zones where 90% of ‘average’ buildings will be destroyed, and other zones where only 10% of average buildings will be destroyed, and the same for where varying percentages of people may be killed or injured.

As can be seen from pictures taken after the explosions in Hiroshima and Nagasaki, even very close to the blast centers, some buildings remained standing, while other buildings, relatively far away, were destroyed.  There’s a lot more to whether buildings and people survive than just distance from the blast, and one of the factors is best described as ‘luck’.

So the numbers we give below are very approximate.

To be specific, a 20 MT warhead (the largest in Russia’s arsenal) would send lethal radiation about 3 miles, almost all buildings and many people would be killed by blast effects up to 4 miles away, and third degree burns (the most serious) would be inflicted on people in direct line of the blast up to 24 miles away (see the table below, taken from the Wikipedia article on this page).



Explosive yield / Height of Burst

1 kt / 200 m

20 kt / 540 m

1 Mt / 2.0 km

20 Mt / 5.4 km

Blast—effective ground range GR / measured in km

Urban areas completely levelled (20 psi or 140 kPa)





Destruction of most civilian buildings (5 psi or 34 kPa)





Moderate damage to civilian buildings (1 psi or 6.9 kPa)





Railway cars thrown from tracks and crushed (62 kPa; values for other than 20 kt are extrapolated using the cube-root scaling)





Thermal radiation—effective ground range GR / measured in km






Third degree burns





Second degree burns





First degree burns





Effects of instant nuclear radiation—effective slant range SR / in km

Lethal total dose (neutrons and gamma rays)





Total dose for acute radiation syndrome






With most bombs likely to be 1 MT or less, the column in the table for 1 MT devices is perhaps most relevant.  If you have a well-built retreat, then as long as you are, say, 5 miles or more away from the detonation, your retreat will remain standing.

As for yourself, it would be nice to be a similar distance away to keep your own overpressure experience to a minimum (ie under 20 psi, although the body may survive up to 30 psi according to page 4-5 of this FEMA document).

There is also a need to avoid the lethal radiation, which will reach out about 2 miles, with diminishing degrees of lethality as you get further away from the blast – for example, you’ll have a 50% chance of dying from radiation (but not so quickly) if you are within 5 miles.

But your biggest worry (ie the threat reaching out the furthest) will be the flash and temperature effects.  If you are outside, you don’t want to have the bad luck to be looking at the bomb (especially at night), and ideally you’d be more than 13 miles from it to avoid even first degree burns.  At 10 miles, you’ll start to get more severe second degree burns, and while normally survivable, in a situation with diminished medical care available, these would be life threatening.  However, if you are inside, you can safely be closer, because the walls of the structure will insulate you from the heat and flash.

So, to summarize, with a 1 MT bomb, you’ll die from either burns or radiation or blast if you are within 5 miles of the blast.  If you’re not sheltered from the direct heat flash, you’ll die from burns if you’re within about 13 miles of the blast.

If you are indoors, then your structure may collapse around you (and on top of you) if it is within 5 miles of the blast, and if it is constructed from flammable materials (ie wood in particular), it might catch fire if within 7 miles.

There is one more immediate risk to be considered.  The blast is going to transform all sorts of things into dangerous flying objects.  You might survive the initial blast itself, only to be skewered by a flying telegraph pole a minute later, or be cut and bleed out from splinters of flying glass.

Here’s the thing – the blast wave travels more slowly than the initial flash.  So if you perceive an enormous flash, you should urgently take cover away from windows or weaker external structures, and wait several minutes until the hail of debris has subsided before venturing out.

Lastly for this part, here’s an interesting web program that shows the estimated ranges of the various effects of a nuclear explosion.  You can choose the power of bomb and where it is detonated, and see its coverage effects accordingly.

In our opinion, the ranges it shows are slightly over-estimated and fail to consider topography and other real-world factors, but it is probably acceptably accurate for the purposes it was created for, and on the basis of ‘better safe than sorry’ it does no harm to consider its results carefully.

Read More in Part Two

This first part of our two-part article has covered the immediate dangerous effects of a nuclear explosion that will occur within the first five minutes or so of a bomb blast.

But unlike a conventional bomb, don’t think that if you survive the first five minutes, then you’re safe.  There’s much more to consider, starting from perhaps about thirty minutes after the blast first occurred.  Please now turn to the second part to learn about the secondary and longer term effects of a nuclear explosion.

Jun 272013
A Civil Defense map from 1990 showing likely fallout patterns after a moderate intensity nuclear war.

A Civil Defense map from 1990 showing likely fallout patterns after a moderate intensity nuclear war.

This is the second part of a two-part article about how close you can be to a nuclear explosion and survive.  If you arrived direct to this page from a search engine or link, we suggest you first read the first part which talks about the immediate effects and dangers of a nuclear blast (covering the first five minutes or so) and how close you can be and still survive those.

Once you have survived the immediate effects of a nuclear blast – the fireball, the flash, the heat, the radiation, the blast wave and the flying debris, you have no time to relax.  There are two more dangers still to consider.

The first danger is that this first nuclear blast may not be the only one.  In a full-out nuclear war, all significant targets will likely be targeted to receive multiple bombs.  We’d suggest that if a first blast occurs, you anticipate that additional blasts may follow, and potentially over a period of an hour or two.  There could be several blasts within ten to twenty minutes from the first wave of missile attacks, and then there might be a second wave of attacks that follow an hour or so later.  Assuming you are in a moderately appropriate place to shelter, stay there for an hour or two in case of additional bombings.

Unhappily, the concern about additional bombs following the first is only one of the reasons to stay sheltered (or to urgently get to shelter).  There’s another major factor that will start to come into play, about 30 minutes after the explosion.

The Danger of Fallout

This is where some type of shelter facility becomes essential.  The bad news part of the immediate effects of a nuclear blast is that you might not have a chance to get to your shelter in time to be protected from them; the good news part is that they are lethal only over a surprisingly short distance (see the first part of this article for a discussion on the range of the lethal initial effects of a bomb blast).

But the fallout from the blast may start arriving at your location as soon as a few minutes after the blast, and might continue arriving for hours or even days afterwards, depending on issues such as wind and rain (see our series on Using Wind Data to Estimate Fallout Risk).

You have two problems with fallout.  Firstly, you don’t want it falling on you or getting in to your retreat/shelter.  Secondly, it will remain ‘out there’ – on the ground, on exposed surfaces, and anywhere/everywhere dust can settle – for a very long time until either washed away, removed, or radioactive levels subside.

Even though the radiation levels from the fallout may be low, they will be continuous and the effects on your health will be cumulative.  Controlling your exposure to fallout radiation is essential.

We talk about fallout in detail on our page Radiation and Fallout Risks.

There is a new concept to introduce to you now – and that is the difference between early and delayed fallout.

Depending on the particle sizes of the fallout material, some fallout will rise further than other fallout.  The heavier pieces go up a shorter distance and come down more quickly – this is termed early fallout.  The lighter pieces will go further up into the atmosphere – some objects may even be shot out into space, happily never to return.  The lighter pieces may get caught up in the jetstreams and be whisked away from where you are.

The immediate problem for you, if you are reasonably close to a bomb blast, is the early fallout.  This will start landing on the ground within 30 minutes of the explosion in the immediate vicinity of where the explosion occurred, and closer to an hour later by the time you get 20 miles away.  By the time you are 100 miles away, it may not start landing until 4 – 6 hours after the event.  These distances are largely determined by the wind speeds and directions, the fallout will not land evenly in neat concentric circles, but will skew strongly in some directions and might not appear at all in other directions.  We can be reasonably sure about the time it will take for the early fallout to come back down again, but we can not guess as to the specifics of where it will land.

All of the early fallout is usually deposited within 24 hours.  The remaining lighter particles can take months before they return to the ground, and may do so anywhere in the world (information taken from p 14 of this excellent 1961 guide).

So even if you survived the initial blast from the bomb, you still need to quickly get to shelter to avoid the fallout.  Depending on how far you are from the explosion, you can expect fallout to start arriving some time from 30 minutes after the blast, and to continue for a day.

How Long to Shelter For

The next part of the process is sheltering until the radiation from the fallout has reduced down to an acceptable level.  How long will this take?  That depends on how much fallout is surrounding you, and also on its rate of decay.

You probably should plan to stay inside for several days before even thinking about what is out there, then at that point, warily stick a radiation meter out a door and see what it says.  If it starts chattering away at an alarming level, quickly retreat back inside and wait a few more days before repeating.  The two readings will also give you a feeling for rate of decline, helping you get a feeling for how much further you are likely to need to keep waiting.  We have a page here about detecting and measuring radiation and will shortly be releasing an article about how much radiation is safe and when it instead becomes dangerous.

Realistically, you should be prepared to shelter for as long as a month or more, and as we discuss in our article on detecting and measuring radiation, if after a month, radiation levels remain dangerously elevated after a month, and show only low rates of reduction, then maybe you are unlucky and have had a particularly large deposit of fallout around your retreat, and maybe you need to consider abandoning your retreat entirely.

Note that while you might choose to shelter for a month or more, you can almost certainly venture outside for very short periods of time during your period of sheltering, although you need to be very careful not to bring contamination with you back into your shelter.  Shoes/boots in particular will have fallout on them after walking around outside, and your outer clothes may too.

While outside you should cover up as much as possible, and we’d suggest breathing through a mask as well, particularly if there is wind and dust outside.  You’d want to remove your footwear and clothing outside the shelter, and shower outside, before coming back into the shelter.

What Is Your Likely Distance From a Nuclear Blast

So we have established that as long as you are inside a strongly built structure and 5 – 10 miles away from a 1 MT blast, or outside and 15 – 20 miles from a 1 MT blast, you will probably survive.

This of course begs the question – how close to a blast are you likely to be?  This is the second of the two key variables to consider (the first being the strength of the blast).  Your distance from any possible blasts is clearly a very important question, but answering it with exactness is difficult, for two reasons.

The first reason is we can’t accurately guess exactly where any possible enemy may choose to target and attack.  But we can probably guess some places they won’t attack – rural locations with no significant industry or airports or harbors or major transportation hubs or other economic or industrial or military objects of value.

The only difficult part of making that prediction is not knowing for sure if there isn’t some super-secret government installation, or similarly secret commercial installation, something/anything of relevant strategic value, and known to the enemy but not to you.  Maybe there’s a huge big data-center or internet resource somewhere in the fields, or who knows what, where.

And even if there isn’t, maybe the enemy mistakenly believes there is!

The second reason is that no-one really knows what would happen in a high intensity nuclear attack. In addition to the unknown reliability and accuracy of enemy missiles to start with, there are three interesting complications.

The first complication is what might happen to the guidance systems of missiles as they go over the north pole.  Depending on how the missiles are guided, this could possibly cause errors to occur.  There have been no missile tests over the pole, so this is all untested theory.

The second complication is what might happen when our defense forces try to counter any incoming missile attack.  Alas, our anti-missile forces are pitifully weak and very few in number, and no-one would suggest they would have any tangible impact on a major attack featuring tens or hundreds of missiles and hundreds or thousands of warheads.

But even if we managed to deploy five or ten ABMs, they might possibly knock some incoming missiles off course rather than completely destroy them, causing the warheads to go and explode in the ‘wrong’ locations – and ending up hundreds or thousands of miles away from their original target.  What if the wrong location they arrived at was, by a bad turn of fate, directly above our retreat?  That’s definitely a consideration, albeit a very unlikely one.

The third complication is similar to the second.  It is not clear what happens to incoming warheads when one that arrived a minute or two or three before the later ones, detonates.  Will the incoming warheads immediately behind still operate, or be destroyed in the blast (a concept known as ‘fratricide’)?

That’s a question of little relevance to us if we’re hundreds of miles away, but a more relevant question is whether the force of the first warhead’s blast might not knock other warheads off course and cause them to veer off target and again end up detonating closer to us than was intended.

Such course deviations are probably not likely to push warheads hundreds of miles off course, but it is certainly conceivable they might deflect a warhead ten or twenty miles.  This is because whereas the ABM attacks take place earlier on the missile’s trajectory, where a small deflection ends up with a larger movement at the end of the journey, the effects of other explosions would impact only on the last twenty or so miles of travel.  Depending on your location, that might be relevant.

So, with a reasonable but not absolute degree of certainty, you can probably determine whether you are in a location that has a high or low ‘appeal’ as a nuclear target.  If your retreat is located in an area that has anything other than a very low degree of appeal, you’ve made a bad location choice!


We don’t mean to understate the potential devastation and catastrophic effects of nuclear weapons.  They are beyond terrible.  But, none of us should overstate their effects, either.  The anti-nuke campaigners, in a manner very similar to anti-gunners, have chosen to magnify the public perception of the outcomes of nuclear explosions, and while many people will die and many buildings will be destroyed, the good news is that very many more people will live.

This is a two-part article.  In the first part we looked at the deadly immediate effects of a nuclear explosion and how far they reached from the explosion’s center; if you have not yet read it, you should probably now do so.

We have a great deal of additional resources on nuclear issues and responses here.

Jun 252013
People observing the nearby Small Boy test in the NV desert, 1962.

People observing the nearby Small Boy test in the NV desert, 1962.

This is the first part of a three-part article that looks at how to calculate the potential impact on your retreat location of the release of radioactive material somewhere else.  In other words, if a nuclear explosion goes off, or a nuclear power plant has an accident, some distance from you, how will that affect you at your retreat?

After you’ve read this first part, please follow the links on to parts two and three, including some worked examples and links to the resource materials you need to do your own calculations and planning.

Once you have started to zero in on an area for your retreat, you then start considering reasonably local issues such as the potential risk of radiation/fallout from nearby nuclear power plants, in the unlikely event something might go wrong with them, and similarly from any probable nearby targets in the event of nuclear war.

Sometimes you can just simply look at a map showing potential risks and guess as to if you’re safe or not.  You don’t need to do too many calculations to understand that downtown DC is probably at great risk of some type of nuclear event, if/when TSHTF.

Unfortunate, there’s no opposite situation where you can instantly tell by a quick glance at a map that any given area is clearly completely safe.  Plus or minus a hundred miles or so, nowhere in the US is more than 250 miles from either a nuclear power station and/or a possible nuclear target in a high intensity conflict.

Although 50 miles is more than enough distance to survive the immediate heat, blast and radiation effects from a nuclear explosion, the fallout radiation implications can be very different indeed.  As we mentioned in our article about the safety of nuclear power stations. dangerous radiation levels as a result of the Chernobyl disaster occurred in what seemed to be a semi-random manner as far as 300 miles away, and radiation from the Fukushima disaster made it all the way across the Pacific to the US.

Note our italics for the phrase ‘what seemed to be’ – because, of course, there is underlying scientific sense that applies to the observed fallout pattern from Chernobyl.  This article series talks about these issues.

Radiation – A Quick Refresher

We discuss the five most common types of radiation in detail in our article on Radiation and Fallout Risks.  Radiation itself is generally both extremely short-lived and also usually only capable of traveling short distances and easily blocked by most things (quite the opposite of public perception).  There is one notable exception to the easily blocked issue – neutron radiation, which while limited in distance to several miles, can penetrate quite a lot of shielding during the course of its travel.

The initial release of radiation from a nuclear explosion is very intense, but only harmful to people within a few miles of the explosion.

The bigger problem is that as part of the nuclear explosion, some of the radiation released will react with non-radioactive materials, and make them become radioactive in the process – that is, they will then start steadily emitting radiation for some time into the future – maybe only hours, but possibly also days, weeks, years, or even centuries.

The second part of this problem is that the heat and blast of the nuclear explosion will turn whatever these things are into finely powdered dust/sand/dirt type particles and then, via the blast wave, propel them long distances.

These tiny particles of now radioactive dust are what is known as fallout and represent the biggest problem that most people will encounter as a result of a nuclear explosion.

So for us, hopefully having located ourselves safely away from the immediate effects of the initial heat, blast, and radiation burst from the bomb, our concern is to do with the fallout.  As you know, normal dust can go anywhere and get anywhere, and if there is radioactive dust falling in your area, it will have the same ability to spread out and cover surfaces, to hang suspended in the air, to be kicked up into dust clouds when the wind blows, and so on.

Furthermore, while the radiation it releases might be weak, there’s one huge danger, and one more insidious danger.

The big danger – if you ingest the dust – by breathing, or if the dust gets onto food or into water – you then have radioactive substances inside you, where there is no distance and no barrier protecting you and your organs from the full effects of the radioactivity.  Even the weak radiation that can only travel a few inches and be blocked by a sheet of paper is now hitting and harming your internal tissues and organs.

The more insidious danger is that low levels of radiation being emitted from fallout may also be fairly long-lived, and so over a period of months (or years) their effects will start to accumulate and cause problems.

So you really want to avoid being in an area with radioactive fallout.

Three Types of Nuclear Explosion

When evaluating your fallout risk, you need to know whether the initial ‘event’ that creates the radioactive fallout will create a little or a lot of fallout, and whether this fallout will be propelled way up into the jetstream or if it will stay closer to the surface.  The ‘jetstream’ is (are) fast-moving bands of air, situated somewhere between about 22,000 ft and 52,000 ft above the ground, and traveling at speeds of anywhere from about 60 mph up to sometimes in excess of 250 mph.

How do you determine the answers to these questions?  You need to decide if the nuclear blast will most likely be an airblast, a surface blast, or a sub-surface blast.


Airblasts are the most common sort, and happily create the least amount of fallout, because the fireball from the blast is mainly above the surface of the ground, and doesn’t impact on as much ‘stuff’ to vaporize and transform into radioactive fallout.  Even more happily, the fallout they do create tends to go up into the upper atmosphere, where it might get caught in the jetstream.

If the fallout gets into the jetstream, this will quickly whisk it away from the site of the blast, and by the time the particles start to drop out of the jetstream again, they may have traveled anywhere from a few hundred miles to many thousands of miles.  The good news is this means the fallout gets dispersed over a very wide area.  The bad news is that while you might not be at risk from a nearby blast, you may get a small amount of fallout from far away blasts (for example the jetstream took fallout all the way from Japan to the US after the Fukushima power plant problem).

Even if the fallout particles from an airblast do not mix into a jetstream, the simple fact of throwing them up a long way means they’ll spread out over a greater area than if they were not thrown up as far to start with.  You can see this for yourself with a simple thought or real experiment.  Take a handful of rice, hold it a couple of inches above the floor, and then drop it.  See where it lands and how it spreads out.  Now, after cleaning up your mess, take a second handful of rice, toss it as far into the air as you can, and see where it lands.  It will be much more spread out, won’t it (good luck with the cleanup!).

Surface Blasts

These are the nastiest of the three types of nuclear explosion.  The initial fireball from the blast is, by definition, right on the ground (or within 100 ft or so of the ground), and will be vaporizing literally tons of material – buildings, dirt, people, anything and everything.  A massive amount of fallout is created.

Much of this fallout does not get thrown as far up into the atmosphere, and will fall back down to earth without reaching the jetstream.

So a surface blast has two severe consequences (compared to an air burst).  The first is the creation of massively more fallout material; the second is that this material is not distributed thinly (and almost safely) over a wide area, but is concentrated in a dense and potentially lethal area, within a few hundred miles of the explosion.

Subsurface Blasts

If the enemy is trying to destroy hardened bunkers, and possibly missile silos, they may use bombs that are designed to penetrate a distance into the ground before exploding.

The best case scenario would be a bomb that traveled so far into the ground before detonating that the earth above it contained the full effects of the blast.  This is what happened most of the time with underground testing of bombs – sure, you’d see the surface rise and blister some, and the shockwave would cause dust to rise from the surface, but it would be non-radioactive dust, and if the calculations were correct, the covering of earth above the bomb would contain the force of the explosion.

However, it is unlikely that missile penetrators would go that deep.  A shallow subsurface blast might actually be even worse than a surface blast, because more of the fireball will interact with material rather than the top half of it less harmfully going upwards into the sky.  A bit deeper and the effects would be similar to a surface explosion, and deeper again and the amount of fallout sent up into the air would start to reduce, as would the height it reaches and therefore the distance it travels.

Nuclear Power Plant Failures

In the case of a nuclear power plant failure, it is likely that the failure will not be akin to a nuclear explosion, but rather it will be some sort of secondary effect caused by runaway heat causing fires and steam buildup (which might possibly then burst through a containment external barrier with explosive force) and the effects of fire and heat and steam releasing radioactive material.

This is most likely to mirror the effects of a surface or subsurface blast, although we again look at the Fukushima event and learn from it – the explosions it experienced sent some radioactive material all the way up into the jetstream.

At the risk of massively oversimplifying, we’re going to say ‘forget about radioactive material that makes it up into the jetstream’; because most of that material goes anywhere and everywhere.  Having happily forgotten about that, we still have to face the remaining reality – ie, that nuclear power plant failures risk releasing potentially large amounts of radioactive fallout type material that will be deposited in the several hundred miles around the plant.

What Type of Blast to Expect

As a quick rule of thumb, attacks on civilian structures will be air bursts because they create the most blast damage over the greatest amount of surface area.

Attacks on hardened (ie military) structures are more likely to be ground or subsurface blasts, because an airburst may not be sufficiently strong to destroy them.  If it is simply an attack on a place with massed troops or equipment, it will probably be an airburst.  Only if the target has unusually strongly constructed buildings will an enemy feel the need to transition from an air burst to a ground burst.  Unusually strongly constructed buildings might include ammunition bunkers (especially if likely to contain nuclear munitions) and some types of airplane protective hangar.

Attacks on bunkers and other underground facilities will definitely be sub-surface.

Continued in Parts Two and Three

Please now click on to the second part of this three-part article series.  Part two explains how the two different types of winds will interact with the fallout and how we can calculate the effect they will have on our retreat location.  The third part then looks at sources and types of wind data you can obtain to work out the impact on your retreat from radiation releases in other places.

Jun 252013
Part of a diagram explaining how jetstream winds are formed (full size here).

Part of a diagram explaining how jetstream winds are formed (full size here).

This is the second part of a three-part article series on using wind data to evaluate the risk of nuclear fallout at your retreat location.

If you arrived here directly from a search engine or link, you should probably go to the first part of the series that discusses the different types of fallout patterns and read that first before reading this second part (and of course, then following the link at the bottom on to the third part of the series).

Jetstream Considerations

If your nearby potential nuclear target is one which you deem likely to receive an airburst, then your calculation becomes fairly simple.  Sure, there will also be some local fallout too, but most of the fallout will be swept up into the jetstream and then distributed pretty much everywhere the jetstream travels.

There are two main jetstreams to consider in the United States.  In the northern part of the country, there may be a polar jetstream, and in the lower states, there may be a subtropical jetstream.  Both of them have their wind blowing generally from the west to the east, but they can also rise northwards or dip southwards, with such movements varying from day-to-day.

In general it is possible to say that while the winds are predominantly flowing from west to east, they start off, on the west coast, with a slightly southerly direction added to their movement, and by the time they reach the east coast they are flowing in a slightly northerly direction.  You can see the current form of the jetstream here.

Here’s an interesting series of four charts showing how much the jetstream can move, with its location plotted over the course of four days.


What this means for us as preppers is that, in general terms, we want to be mildly concerned about airblasts that might occur to the west of our location – whether they are directly west, to the northwest, or the southwest.

But in reality, jetstream carried fallout is not a great concern, due to it being distributed so widely.

An exception to that is if you’re downwind of the potential jetstream plume from many nuclear blasts – this is of course the case in much of the eastern United States.  Due to the potential distance between the source of radioactive fallout and where it lands, this is about as accurate a statement as one can make – the further east you go, the greater the fallout from the jetstream you might get.

Closer to the Surface Wind Patterns

If you need to evaluate the likely effect of closer to the surface fallout, ie from a surface or subsurface blast, or from a nuclear power plant mishap, then you have a much more complex – and much more important – calculation.

First of all, to show the degree of variability of fallout from a ground burst, have a look at this map of remaining contamination from Chernobyl (as of 1996).  As you can see, some areas close to Chernobyl are looking fairly safe, while other areas, a much greater distance away, are looking still very dangerous.

A much more dramatic view of the fallout from Chernobyl can be seen in this animated graphic which shows how the fallout traveled over time.  It isn’t clear exactly what the colors represent or what the time frame is, and an email to the person who posted the animation on Youtube went unreplied.

We guess this is showing lower atmosphere winds, and in total, probably over a ten to twenty day period.  Another way of ‘calibrating’ this animation is to understand that it took two days for fallout to reach a point in Sweden just out of Stockholm, 700 miles away (in other words, the fallout cloud was traveling at a rate of about 15 mph).

Another example of fallout distribution is shown in this chart, reporting fallout from the largest ever US nuclear explosion – the ground burst of the Castle Bravo device in 1954.  Fairly consistent winds, and less ‘friction’ caused by the sea, rather than the interference and disruption to smooth wind flows on shore (buildings, trees, hills, etc) saw high levels of fallout as much as 280 miles to the east of the explosion, but barely ten miles to the west.

The blast scooped out a crater almost 1¼ miles in diameter, and up to 250 ft deep.

The 15 MT Castle Bravo outcome can be considered a ‘worst case’ scenario.  Currently Russia has some 20 MT warheads on its SS-18 missiles, but most of its missiles are armed with warheads ranging from about 100 kT up to 1 MT.

Learning from Volcano Eruptions Too

More information about how fallout would travel can be obtained, in general, by looking at ash distribution from volcano eruptions.  Volcano ash distribution is interesting, and needs to be considered in light of the height the ash rises to in the atmosphere – sometimes it reaches well up into the jetstream, and sometimes it doesn’t.

The Eyjafjallajökull volcano eruption in Iceland in April 2010 disrupted air traffic over much of Europe for a couple of weeks, due to the enormous amount of ash thrown up by the volcano (about 130 million cubic yards), and its wide spread around much of Northern Europe.  Some of the ash made it up into the jetstream.

Here is an interesting series of maps showing the fallout spread as it evolved during the period of major activity by this volcano, and this page has an interesting discussion of how clouds of volcanic ash (or fallout) are swept along by winds).

Understanding the Relevant Wind Patterns in General

To appreciate your degree of risk from lower level fallout (ie fallout that only rises a limited distance into the atmosphere and then drops back down to ground, missing the jet stream) you need to ‘join the dots’ between wherever the radioactive fallout might be released and where you are.

By this we mean you draw up a series of charts showing the prevailing winds at your location, at the point where the release would occur, and at relevant points in-between.

The first point to focus on are the prevailing winds at your planned retreat.  If your retreat generally has winds blowing towards the possible release location, that’s a very good thing.

But there’s a bit of a trap to consider, which requires you to look at more data to better understand things.  For example, let’s assume you are at Point R and the nuclear fallout comes from Point X, and you ascertain that the wind at your retreat (Point R) is blowing towards Point X, where the radiation release occurred.  So that means you’ve nothing to worry about, right?

Not necessarily.  Let’s also see where the wind at Point X is blowing.  You do that and you believe you’ve found more good news – the wind isn’t blowing directly towards you, instead, it is blowing at right angles to you.  Here’s a sample picture showing this – we use red arrows for winds carrying contamination from the release point, and green arrows for ‘safe’ winds.


So that looks close to optimum, don’t you think?  We’ll agree that you’re a prudent person, and so you obtain some more wind readings, and now you see a more detailed view.


This looks even better, yes?  But let’s not stop, let’s be obsessive and get as much wind data as we can.  You do some more research, and now you see this as a wind flow model.


This would seem to confirm all you need to know, right?  However, with so much information on the internet these days, and remembering just how far fallout can be carried by even mild winds, let’s grab some more data.


What do you think now?  Could it be…?  Let’s get a few more data points, and all of a sudden :


This now shows a very different scenario, doesn’t it.

As you’ve already seen in the real world examples linked to above, winds – and whatever they carry can travel on irregular paths, like a meandering river delta, with lots of crossing and inter-twined threads.  The winds that start blowing down the image in the first example then looped around and started blowing up again, taking the contamination and dumping it directly on you, even though your first data points seemed to suggest completely the opposite.

Clearly, this was a staged example, not a real world one.  But it teaches us two things.  First, we need to trace not just where the wind blows to, from our retreat, but also where winds are coming from prior to getting there.  Second, we need to follow the wind flow from the contamination release point for at least 200 miles to get a feeling for what twists and turns they might take.

Okay, so that’s an easy enough concept to be aware of.  But there’s a complicating factor that you’re probably already thinking of.  Winds don’t blow steadily, all day every day (and all night) and always from and to the same directions.  How do we factor in the variable aspects of wind flows/currents?

Read More in Part Three

To answer the question about understanding and applying the wind data information you have collected, please now click on to the third part of this three-part series, Available Wind Data Sources and How to Use Them.  Also, if you’ve not yet read it, the first part of the series, Using Wind Data to Estimate Fallout Risk, is also, of course, helpful and relevant.