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Sunday, September 6, 2009

Reading List: Feux follets et champignons nucléaires

Charpak, Georges et Richard L. Garwin. Feux follets et champignons nucléaires. Paris: Odile Jacob, [1997] 2000. ISBN 978-2-7381-0857-9.
Georges Charpak won the Nobel Prize in Physics in 1992, and was the last person, as of this writing, to have won an unshared Physics Nobel. Richard Garwin is a quintessential “defence intellectual”: he studied under Fermi, did the detailed design of Ivy Mike, the first thermonuclear bomb, has been a member of Jason and adviser on issues of nuclear arms control and disarmament for decades, and has been a passionate advocate against ballistic missile defence and for reducing the number of nuclear warheads and the state of alert of strategic nuclear forces.

In this book the authors, who do not agree on everything and take the liberty to break out from the main text on several occasions to present their individual viewpoints, assess the state of nuclear energy—civil and military—at the turn of the century and try to chart a reasonable path into the future which is consistent with the aspirations of people in developing countries, the needs of a burgeoning population, and the necessity of protecting the environment both from potential risks from nuclear technology but also the consequences of not employing it as a source of energy. (Even taking Chernobyl into account, the total radiation emitted by coal-fired power plants is far greater than that of all nuclear stations combined: coal contains thorium, and when it is burned, it escapes in flue gases or is captured and disposed of in landfills. And that's not even mentioning the carbon dioxide emitted by burning fossil fuels.)

The reader of this book will learn a great deal about the details of nuclear energy: perhaps more than some will have the patience to endure. I made it through, and now I really understand, for the first time, why light water reactors have a negative thermal coefficient: as the core gets hotter, the U-238 atoms are increasingly agitated by the heat, and consequently are more likely due to Doppler shift to fall into one of the resonances where their neutron absorption is dramatically enhanced.

Charpak and Garwin are in complete agreement that civil nuclear power should be the primary source of new electrical generation capacity until and unless something better (such as fusion) comes along. They differ strongly on the issue of fuel cycle and waste management: Charpak argues for the French approach of reprocessing spent fuel, extracting the bred plutonium, and burning it in power reactors in the form of mixed oxide (MOX) fuel. Garwin argues for the U.S. approach of a once-through fuel cycle, with used fuel buried, its plutonium energy content discarded in the interest of “economy”. Charpak points out that the French approach drastically reduces the volume of nuclear waste to be buried, and observes that France does not have a Nevada in which to bury it.

Both authors concur that breeder reactors will eventually have a rôle to play in nuclear power generation. Not only do breeders multiply the energy which can be recovered from natural uranium by a factor of fifty, they can be used to “burn up” many of the radioactive waste products of conventional light water reactors. Several next-generation reactor concepts are discussed, including Carlo Rubbia's energy amplifier, in which the core is inherently subcritical, and designs for more conventional reactors which are inherently safe in the event of loss of control feedback or cooling. They conclude, however, that further technology maturation is required before breeders enter into full production use and that, in retrospect, Superphénix was premature.

The last third of the book is devoted to nuclear weapons and the prospects for reducing the inventory of declared nuclear powers, increasing stability, and preventing proliferation. There is, as you would expect from Garwin, a great deal of bashing the concept of ballistic missile defence (“It can't possibly work, and if it did it would be bad”). This is quite dated, as many of the arguments and the lengthy reprinted article date from the mid 1980s when the threat was a massive “war-gasm” salvo launch of thousands of ICBMs from the Soviet Union, not one or two missiles from a rogue despot who's feeling “ronery”. The authors quite reasonably argue that current nuclear force levels are absurd, and that an arsenal about the size of France's (on the order of 500 warheads) should suffice for any conceivable deterrent purpose. They dance around the option of eliminating nuclear arms entirely, and conclude that such a goal is probably unachievable in a world in which such a posture would create an incentive for a rogue state to acquire even one or two weapons. They suggest a small deterrent force operated by an international authority—good luck with that!

This is a thoughtful book which encourages rational people to think for themselves about the energy choices facing humanity in the coming decades. It counters emotional appeals and scare trigger words with the best antidote: numbers. Numbers which demonstrate, for example, that the inherent radiation of atoms in the human body (mostly C-14 and K-40) and the variation in natural background radiation from one place to another on Earth is vastly greater than the dose received from all kinds of nuclear technology. The Chernobyl and Three Mile Island accidents are examined in detail, and the lessons learnt for safely operating nuclear power stations are explored. I found the sections on nuclear weapons weaker and substantially more dated. Although the book was originally published well after the collapse of the Soviet Union, the perspective is still very much that of superpower confrontation, not the risk of proliferation to rogue states and terrorist groups. Certainly, responsibly disposing of the excess fissile material produced by the superpowers in their grotesquely hypertrophied arsenals (ideally by burning it up in civil power reactors, as opposed to insanely dumping it into a hole in the ground to remain a risk for hundreds of thousands of years, as some “green” advocates urge) is an important way to reduce the risks of proliferation, but events subsequent to the publication of this book have shown that states are capable of mounting their own indigenous nuclear weapons programs under the eyes of international inspectors. Will an “international community” which is incapable of stopping such clandestine weapons programs have any deterrent credibility even if armed with its own nuclear-tipped missiles?

An English translation of this book, entitled Megawatts and Megatons, is available.

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