Comparison of Nuclear Accidents versus Nuclear Bombs: Part 1

This is the first in a series of posts comparing the negative consequences that follow from a nuclear meltdown from a nuclear power plant to those following from the use of a tactical nuclear weapon.

The motivation behind this planned blog post came from Putin seizing various nuclear power plants is Ukraine.  Putin has been using its ownership of nuclear weapons as insurance against the major powers  engaging against its forces directly.  Since no one wants a full-out nuclear war, no power with nuclear weapons in the West wants to engage directly with another nation with nuclear weapons out of fear of what will happen.  

If Putin were to use a nuclear weapon *first*, this would instantly change that calculation.  But then the question was raised: if Putin is willing to shell nuclear power plants and maybe even engineer a nuclear meltdown or a dirty bomb and blame the Ukrainians (a speculated course of action), would that "count" as the use of a nuclear weapon, and therefore trigger a recalculation which would justify the direct involvement of NATO forces on the battlefield in Ukraine?

This comparison between a nuclear meltdown (potentially engineered) and the use of a tactical nuclear weapon is directly relevant to this question.

This post is going to clear up a few initial issues and explain why some available comparisons are inadequate.  I will then follow up with a post on estimating the consequences of nuclear weapons, followed by a similar post on nuclear meltdowns.  Finally, I will draw some tentative conclusions--but you should be warned, this is a difficult comparison to make and my conclusions will be very tentative.  In the end, I hope to have provided at least a framework for thinking about this problem, if not any other useful conclusion.

But let's get right to clarifying some initial points:

Tactical vs. Strategic Nuclear Weapons

So the first point to clear up is this term, "tactical nuclear weapon", which is a phrase that many people don't understand right away. In this phrase, the word "tactical" refers primarily to the intended purpose of the weapon, but also secondarily to the power of the weapon.

The opposite of "tactical" in this context is "strategic".  A "strategic" nuclear weapon is a large missile aimed at major population centers of your opponent's nation, and the goal of such a weapon is to be an existential threat to your enemy.  That is, by having such nuclear weapons, you have, as an option, the ability to threaten the end of your enemy's existence itself, if the existence of your own State is threatened.  This is the origin of the phrase "Mutual Assured Destruction", and it is the essential point of strategic nuclear weapons.

Tactical nuclear weapons, on the other hand, are designed to be used on the battlefield in order to achieve specific military objectives as part of a specific military campaign.  The classic example of such a purpose is the theoretical use of a nuclear weapon by NATO as a contingency to stop a mass blitzkrieg of Russian tanks from storming the Fulda Gap and taking Europe in a sudden surprise military operation.  [Note: this was back before we realized that a few shoulder fired missiles and some farm equipment can apparently do the job just as well.]  Such a use of nuclear weapons--for a specific battlefield need--would be a tactical use.

Because of the much more limited intended scope of application, tactical nuclear weapons tend to also be considerably smaller than strategic nuclear weapons (though strategic nuclear bombs can also just be the same or similar bombs, just delivered in clusters in order to be have a larger total yield as well as being harder to defend against).  It is important to realize that this size difference can be immense.  Nuclear bombs have been developed that range in size all the way from a 10 ton bomb to a 50 megaton bomb--yes, the largest nuclear weapon ever detonated is a full 5 million times larger than the smallest one ever.  This means there is going to be a necessarily large range of possible consequences to the use of a nuclear weapon: it matters a lot how big that weapon is.

Next point of clarification:

"Radiation released" is a poor metric of the seriousness of consequence

If you look at the wikipedia entry comparing Chernobyl and other "radioactivity releases", you will see that Chernobyl released about 400 times the amount of radioactive material into the atmosphere than the nuclear bomb dropped on Hiroshima.  So were the negative consequences of Chernobyl about 400 times worse than those of Hiroshima?  Well . . .

If you compare the loss of human life between Chernobyl and Hiroshima, on the other hand, you will see that the number of people who died immediately at Chernobyl was 28, followed by something like 14-23 more people over the next 10 years due to the radiation exposure.  Long-term increases in cancer rates due to Chernobyl are very hard to determine--there have been some wild estimates out there based off of "Linear, No-Threshold" calculations, but I don't find these worth considering.  Only regional increases in thyroid cancer, mostly in children, can be clearly linked to radiation released at Chernobyl, which accounts for about 4000 cases of cancer of a low mortality rate, resulting in 9 deaths.  Plausible estimates for the number of people we would expect to have somewhat shortened lifespan because of high levels of radiation exposure are in the range of 4000 people--but the average decrease in lifespan is pretty low.

At Hiroshima, on the other hand, between 90,000 and 140,000 people died immediately or due to the immediate aftereffects of the bomb.  Long-term increases in cancer account for maybe about 200 known deaths and 1700 extra cases of cancer.  There have been some studies that show an average decrease in lifespan among the thousands of other people exposed to radiation from the bombing, but average decrease is again, pretty low: "a few months".

So on the whole, while Chernobyl released "400 times" the radiation that Hiroshima did, the final death toll it produced was something in the area of 50-100 people (depending on how you count the small decreased lifespan of a large number of people), whereas the death toll of Hiroshima was roughly 1000 times higher.

Let's make another comparison!  Fukushima was another nuclear accident which has released a large amount of radioactive material to the environment; approximately 1/10th the amount that Chernobyl released.  If you could compare these accidents as apples-to-apples on the amount of radiation released, then you would expect around 5-10 people to have died from that result.  But, in fact, no deaths--and in fact no adverse health effects at all--are currently attributed to the radiation released by the accident, and none are expected (though a number of deaths have been attributed to the evacuation done out of fear of the released radiation).

Here's yet another comparison point.  In the '50s and '60s, many nuclear tests were carried out by the nuclear powers.  A lot of the radioactive fallout of these tests were propelled into the upper atmosphere and diffused across the entire world.  In total, nuclear testing is thought to have released between 100 and 1000 times as much radioactive material into the atmosphere than Chernobyl did.  If you could compare the consequences of a nuclear event based on radiation released, you would therefore expect the number of people that have died as a result of this released radiation to be something like 5,000 to 100,000.  But, in fact, the best calculations we have done on this show that there has been zero health effect on the general population as a result of this testing, at all, ever.

So the bottom line here is that "radiation released" is a stupid metric.  It does not correlate meaningfully with negative consequences in the historical examples.  It should never be used because it gives the illusion of an objective grounds of comparison but in fact doesn't tell you anything useful by itself.

First Conclusion

Therefore, the first conclusion of this series is that if you want to reasonably compare the seriousness of a nuclear meltdown vs. the use of a nuclear weapon, you need a better framework of comparison than just "radiation released".  We will begin to build this framework in the next post in this series.