Fear not radiation

Radiation and Reason, Wade Allison, 2009

In summary this book presents evidence to show that there is no known harm to us for radiation levels that do not exceed 100 millisieverts per month, with a cautious life-time limit (for now, maybe it could be higher) of 5,000 millisieverts. The International Commission for Radiological Protection limit is 1 millisievert per year so the argument is that this is about 1000 times too restrictive.

The Sievert is an attempt to give a unit to effects of radiation in living tissue. Although other units have to be used in particular situations for precision, the book is not concerned with fine detail and everything is assessed via the millisievert.

Cornwall in the UK has background radiation at 8 millisieverts per year, and that is as high as anywhere in the country. Cancer radiation treatment is 1000 to 10,000 millisieverts in a session, though this is meant to be targeted on the tumour with geometry to minimize radiation in healthy tissue. Numbers such as these present the arena for the discussions in the book.

The aim of the presentation is to suggest that safety limits could be relaxed a thousand fold, thereby making fission nuclear power stations cheaper; they must be structurally robust with multiple fail-safe mechanisms, but they do not need to be so radiologically protective. Especially decommissioning should be much easier and cheaper and not the huge bogeyman that it is currently made to be.

Prof Allison is not doing this to win favour with the nuclear industry but because, like me and others, he is concerned for the human future because of global warming. We have to take a balanced view of risks.

There are good simple discussions of radioactive decay, atomic weapons and nuclear power reactors, and the biological effects of radiation. Even so the book is not for the innumerate or those lacking any scientific background. I would hope that it might be read by policy makers and their advisors. I notice that he is the publisher of the book so I hope he has persuaded the publisher to send a few copies to UK MPs and European MEPs.

The most pertinent discussion is on biological effects of radiation. He points out that the no-safe-dose idea is totally wrong – there is a threshold at which irreversible damage occurs and below that cell repair mechanisms deal with any damage. In fact in morbidity studies people with exposure to radiation lower than the limit he suggests seem to live longer: a little radiation may be a good thing. He makes a good analogy with sunbathing (page 34): too much sun bathing causes damage to skin and sometimes skin cancer, but too little exposure leads to lack of Vitamin D. The demolition of the Linear No-Threshold and Collective Dose models is excellent. There is analysis of Japanese survivors of the atomic bombs of 1945 with the amazing statistic that those who survived to 1950 had only a 4 in 1000 chance of dying of radiation induced cancer.

There is an excellent contrast made between current fossil fuels and nuclear fuel. Fossil fuels put CO2 into the air where it dilutes and distributes globally as well as toxic substances that are then buried but never lose their toxicity. The nuclear waste from a power station after reprocessing is much smaller in volume by a factor of about a million, and any radiation dangers decrease with time; these are volumes we can cope with.

Although he does not point it out explicitly, when people mention long half-life they often miss that this means low activity, the high activity nuclear products have short half-life (maybe years) so if we wait a reasonable time they make themselves safe. 

Page 108 has a table of deaths from various disasters in which the Chernobyl and Three Mile Island reactor accidents are at the low end counting for about 50 and zero deaths. My own favourite comparison (not in this table) is with traffic accident deaths that are in the range 40,000 to 50,000 per year in the EU: a Hiroshima and Nagasaki every two years.

There is a good discussion of the differences between nuclear refinement for power stations versus weapons, though this may not be as easy a political issue as the discussion suggests. Compare Nuclear arms will soon proliferate. So here’s a plan to scrap them all.

I found the suggestion on page 159 that people should be given devices to enable them to ‘see’ radiation levels a bit naive as I suspect that interpretation of what we have not evolved to see takes expertise. Just consider how people are assessing their sense of global warming from experience. I think that better general science education is the key.

I have never myself had a problem with the technology of nuclear power, but I thought that the costs probably made it non-viable. This book attempts to address the cost issue but we need some new careful estimates of costs given the proposed relaxation of safety limits that the book does not provide. David Mackay, Sustainable Energy – without the hot air, provides some rough guides for this.

I await a review of the book by someone with expertise in radiobiology to see what weakness there is in the argument.

Finally I agree totally with the comments on page 194 about specialization. Although each of us may have some specialty we need to have the big picture of how the specialties connect up and be able to see where we are being led.

My minor quibbles:
That the bombs dropped on Hiroshima and Nagasaki were a military and political success (page 5) I think is still debateable. I think the statement was meant to contrast with the lasting suspicion of nuclear power he mentions ever after those events but feels a bit gung-ho.

For anyone who cannot work it out for themselves the graph on page 121 comparing chronic and repeated doses of radiation would not help. I found it confusing at first.

Another odd slip for an otherwise good simple description of the physics of fusion and fission is on page 134 where it says that the neutron being uncharged can enter straight through the coulomb barrier: rather, for the uncharged neutron, there is no coulomb barrier.

On page 133 there is a dismissive footnote on cold fusion that says “predictably, its hopes have not been realised.” I admit that when I first heard about it 1989 I felt it impossible that it could work; now I am not so sure and I certainly don’t think it is predictable that it does not. The footnote just above this one mentions quantum tunnelling so there is clearly a non-zero probability that cold fusion will happen, a minute probability in free space but maybe much greater in some material lattice. I still think it unlikely, but I would not want to be totally dismissive.