Hello Prof. Bodansky,
I’m a PhD student in geophysics, and I just finished reading your book, Nuclear Energy. I appreciate the trouble you went to in the book to remain effectively neutral as to whether we ought to be pursuing the development of nuclear power. While I can’t say that the book made me into a nuclear advocate, I am less opposed to it in principle now, and believe that it does represent a potential long term energy solution, albeit one with non-trivial caveats. Then again, that seems to be the case with all of our options at this point.
In particular, I liked the discussion of long term, intergenerational ethics which you brought up in connection with waste disposal, because it is applicable to so much more than just nuclear waste, and because while you did point out the huge disparity between our assessment of the risks associated with radiological hazards vs. other forms of pollution, environmental degradation, or more general societal sources of human suffering, you did not use that disparity to argue that we are being too cautious in our approach to waste disposal (or nuclear power in general). I appreciate that because I think it is probably more likely in the long run that we are for some reason being appropriately cautious with respect to nuclear hazards, and inappropriately cavalier in many other contexts.
The only significant criticism I can think to direct at the book is in regards to the methods described for assessing the probability of accidents. I would submit that serious releases of radiation are most likely not to be the product of several independent low probability events taking place, or even of “weak link” or “common mode” failures as described in your book. Chernobyl was, by your own description, not really that kind of accident, as many of the reactor’s safety systems had been disabled for the purposes of the test which was underway. I suspect that there are significant irreducible risks of human error or malicious intent. In the event that we choose as a civilization to pursue nuclear energy as a significant primary power source, with terawatts of installed generating capacity, the right standard in my mind is how safe the reactors are when they are located in a war zone, and operated by an occupying army who has no idea what they’re doing, or who might actively try to precipitate the release of radioactive material. In the fullness of time, with thousands or tens of thousands of nuclear power plants installed globally, surely such a scenario would take place eventually, and potentially more frequently than would be deemed acceptable by those assessing the risk of truly accidental accidents. I am encouraged that many of the reactor designs currently under consideration incorporate passive safety features, and hope that in time we may arrive at a design so simple and inherently incapable of uncontrolled criticality or overheating that these human risks are no longer significant.
A lot of my discomfort with low probability high consequence events comes from having some familiarity with inverse modeling problems, as described for a non-technical audience by Nassim Taleb (“Fooled by Randomness” and “The Black Swan“) and for a technical audience by Albert Tarantola (at the Institut de Physique du Globe de Paris). If you are not already familiar with them, and have the time and inclination, I think both writers are worth attention.
Thank you again for your work,
Zane Selvans
Dr. Bodansky thoughtfully took the time to reply:
Dear Mr. Selvans:
Thank you for your very thoughtful letter. I am sorry that my response is so tardy. You raise an interesting set of issues, and I don’t have fully satisfactory answers.
Despite the many discussions of possible causes of reactor accidents, I had previously never seen a discussion of the risks from a victorious invader. You distinguish between inadvertent releases of activity, occurring out of ignorance, or intentional releases with the aim of doing harm. The inadvertent releases would presumably follow some malfunction which would cause a loss of cooling. In such a case, I believe all reactors (certainly all new ones) are designed to shut down by the automatic insertion of control rods.
That leaves the problem of the decay heat. Existing reactors require operator intervention and in a war scenario they might be all killed or have fled. New HTGRs are supposed to cool harmlessly by radiation. The situation for the AP-1000, a leading advanced PWR, is ambiguous (at least for me), but I believe that most other water cooled reactors might eventually overheat, with serious fuel damage. That does not necessarily mean a large radiation release (witness TMI) but it might. This suggests that some thought be given to such wartime scenarios if reactors are installed in vulnerable countries.
No precautions could thwart the efforts of a malicious army that sees the radioactivity as a weapon. But noting the tremendous harm done with very low-tech methods in recent African conflicts, I do not see the point of using reactors — except perhaps to promote panic. More harm might be done were the invader to disable the electricity grid or disrupt or poison the water supply.
To me it makes sense to differentiate between relatively secure countries (including China and India) and insecure countries (mainly in Africa and the Middle East). I can see no real possibility of the former being overrun without a nuclear war. Bombs have a much greater potential for damage than reactors — so much greater that reactors should be welcomed if they are a means of promoting economic stability and hence a more peaceful world.
Reactors in “insecure countries” are another matter and I think we should be cautious in terms of their introduction. Unfortunately, matters are not always under our control — e.g. Iraq, North Korea, and even maybe Pakistan. Already some thought has been given to making very proliferation-resistant systems for developing countries. It might be desirable to try to make them sabotage-resistant also. Further, it serves as an argument for pushing solar power (broadly defined to include wind, etc) in these countries where that might suffice if electricity expansion starts from a low base.
Thanks for calling the books by Taleb and Tarantola to my attention. And thanks also for giving me something “new” to think about in regards to nuclear energy.
With best wishes,
David Bodansky