Dear Robert Williscroft,
I got aware of your homepage and read your articles about the Nuclear Energy Option, Nuclear Waste and Breeder Reactors, and Chernobyl. [Editor’s note: See also Nuclear Power 101, The Grand Experiment, The Chernobyl Aftermath, Three Mile Island] You have good arguments, a good knowledge of the technical details, and a talent to explain it in a way that it’s understandable for non scientists, too. That doesn’t mean that I share every point of you. For example, your suggestion, to dispose of the nuclear fuel in the Challenger Deep didn’t convince me at all. Would the borated glass encased drums not brake in such a way that the radioactivity would leak to the water?
I’m interested if the accident in Fukushima (caused by two major nature catastrophes) affected your judgment and beliefs about nuclear energy, and if yes, in which way. The reactors were built with secure American technique (no dangerous Chernobyl reactor type, construction included containment etc.), and also there was no major human mistake which led to the accident. Japan is a high technique country.
Could it be that science simply cannot assess every possible (combination) of incidents and be prepared for it? Also, even if the likelihood of a worst case is very low, should not be the expectation value the guidance for any decision? Even a very low risk (which seems not to be easy to calculate because of the assumptions one always has to make) multiplied with a fatal outcome makes an expectation value which a society may be not willing to accept.
In Germany, for example, a big majority of people doesn’t accept it anymore. If this is dumb or not I don’t assume to judge. Government decided the 7 oldest nuclear power plants to shut down (I know it’s not so simply with reactors), very likely with no return. The mid term exit of nuclear energy production which was already decided before will be once more fastened (by a conservative leaded government). Of course, than you need other alternatives which have there problems and their costs, too.
Don’t misunderstand me; I’m not a green dreamer, I’m rather conservative. It is that why that I’m interested in your opinion.
Best regards,
Marcus
My Response:
Thank you, Marcus, for your thoughtful letter. First I will address the disposal of spent nuclear fuel rods in the Challenger Deep. My real point was that there really is no “nuclear waste,” but rather a raw material resource that we should be using, not throwing away. Given, however, that we actually have a lot of so-called waste that we have encapsulated in such a way that it is impractical to extract usable materials, we end up with a disposal problem.
The Challenger Deep Solution
The potential problem you raised in your letter, namely the possible breaking of the containment vessels in the Challenger Deep, is missing the point a bit. The “waste material” is ground up and encapsulated in small borated glass beads. These beads have been extensively tested (without any radioactive content), and been shown to withstand breakage or other degradation for at least 10,000 years. The beads are then encased in hardened concrete inside steel barrels. This is how they will be stored in Yucca Mountain, or wherever they end up.
The links I added to your letter point to portions of my book, The Chicken Little Agenda, that discuss the issues you raised. They go into the matter a little deeper than the articles you read on my website. I will address the subduction issue first.
The Challenger Deep is the location where two tectonic plates intersect. One plate is quite literally being drawn underneath the other. In just a short few hundred years, anything deposited in the Challenger Deep will be drawn right into the Earth’s mantle, where it will become a part of the mantle, indistinguishable from any other part. Since the Earth’s mantle is nearly 2,900 km deep, and since the temperature inside the Earth is largely a factor of radioactivity, the minuscule additional amount contributed by the canisters would have no effect whatever. The canisters would simply vanish as they are drawn into the Earth’s interior.
The potential for radioactive material leaking into the surrounding water is limited to the few hundred years before the canisters are subducted, and the canisters have been demonstrated to maintain their integrity for 10,000 years. Furthermore, even if some radioactive material leaked into the surrounding waters, the Earth’s oceans are so vast, and that area is so deep, that any leakage would quickly be diluted beyond measurability. It is difficult for most people to comprehend how vast our oceans really are. The latest Woods Hole measurement for the volume of our oceans is 1.3 billion cubic kilometers, with an average depth of just over 3.6 km. 1.3 billion cubic kilometers is a staggeringly large number, completely incomprehensible by a normal human. A tiny amount of radioactivity leaked into such a large volume simply has no effect at all.
Nuclear Reflections Following the Japanese Earthquake and Tsunami
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Absolutely everything humans do involves some level of risk. The long-term solution is to manage risk so that the derived benefit makes any remaining risk acceptable. As in America, Germans drive cars. As in America, the German automobile accident fatality rate is unacceptably high, and yet virtually everyone in both countries drives every day. One might conclude, therefore, that while the fatality rate is high, it is not unacceptably high, since we all accept it as part of driving.
The same reasoning applies to power production. Both America and Germany (as well as France, Japan, England, etc) have included at least some nuclear power generation. The Japanese plants were built to “normal” standards of several years ago, and, unfortunately, were not designed to withstand the level of seismic activity that actually happened. The irony is that the core containment shells could have been constructed on rollers that would have largely eliminated the mechanical damage to the reactors themselves.
The real problem, however, was that the cooling systems and their redundant backups had no way to receive power. The designers never considered that possibility – an obvious blunder in retrospect. Without this power, there was no way to draw off the residual heat generated by the core, which lead to super-heated steam that broke down in contact with zirconium in the rods into hydrogen and oxygen, that ultimately exploded.
You comment that the Japanese reactors were built following an American “safe” design. In fact, they were built on a General Electric template that is the standard for world-wide civilian nuclear reactors. The GE design is larger and less efficient than the original Westinghouse design used in most nuclear submarines (although current nukes use a modern GE design very similar to the earlier Westinghouse designs). In both designs, with the control rods fully inserted, the reactor shuts down – ceases its self-sustaining nuclear reaction. You still need primary cooling water, however, to keep the residual core temperature under control. Should it reach 2,200 degrees Celsius, the water will break down into hydrogen and oxygen, with the possibility of an explosion – as happened in Japan. Consequently, if you lose the ability to pump coolant water, you will have a problem.
Under virtually all normal circumstances, modern nuclear power plants are perfectly safe. Japan presented the world with a dramatically over-the-top situation that exceeded nearly every design parameter of their well-designed plants. Despite this, the plants retained their integrity until the tsunami wiped out their auxiliary power generation capability. With hindsight, this was a preventable problem.
Future reactor design will take one of two different tacks, the pebble-bed reactor, and the gas core reactor. These both are inherently more safe and efficient than present boiling water (BWR) and pressurized water (PWR) reactors. Until we develop space-based solar-power satellites or thermonuclear fusion power, or the even more remote nuclear electrolysis (cold fusion) model, modern nuclear power plants are our safest, most reliable way of generating large amounts of electricity. We should not let poor media reporting and general misunderstanding of nuclear power and “radiation” deter us from continuing to pursue this option.
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