7-2: On the Risks and Benefits of Plutonium Recycling

In his Chapter, The Civilian Use of Nuclear Energy, Garwin makes use of an interesting analogy to explain France’s decision to reprocess and recycle its plutonium and uranium as opposed to choosing the American direct disposal strategy. Like the forward thinking automobile industry that invests in alternate uses of energy by increasing its gas mileage and decreasing its reliance on oil, France’s decision to reprocess was motivated by the expected scarcity of uranium. Much like the automobile industry, the logic was: “One day the price of oil will go sky-high. One day the price of uranium will also climb; then it will be economical to use breeder reactors, to reprocess light water reactor fuel and to recycle the plutonium and uranium”.

This economic gamble, despite its obvious moral advantages due to its reduction of waste (it is estimated that in 2020 the French stock of nuclear waste will contain 150 tons of plutonium vs the 1000 tons of plutonium waste in the USA), has proven to be less profitable and economically efficient as the direct disposal approach. The short terms costs are much higher, and it appears as if the long term economic efficiency is very far away from being obtained (the breakeven price for uranium is approx. $700 per kg compared with the current $30-40 per kg prices) especially given that technologies for mining uranium from low-grade ores and seawater could prove to be cheaper.

When trying to compare the long-term safety and economic efficiency of the two main approaches to nuclear waste, reprocessing and direct disposal, the first option introduces immediate dangers while the second focuses on long term dangers. The main safety issue with reprocessing is the potential for saboteurs or terrorists to acquire the separated plutonium during the recycling process. This is obviously a very important danger to consider, for the consequences could be disastrous, but the likelihood could be reduced with an increase of security measures.

The dangers of the direct disposal method require much more of a mental exercise, because they span over hundreds of thousands of years, and they raise many interesting questions. What are the chances that the nuclear waste buried in steel cases in the Yucca Mountain reenter the biosphere because of earthquakes, volcanoes, meteorite impact, or human intrusion over the next million years that it takes for the uranium to finally return to its natural state? Will the steel cases last long enough, or should we resort to incorruptible metals such as gold? In as little as a few thousand years, the conditions for return for the nuclear waste into the biosphere will most likely be radically different.

In this way it is virtually impossible to provide any guarantee of the safety of the depositories over beyond a thousand or so years. But then again, it is also impossible to predict our human capability in a thousand years to be able to deal with the nuclear waste. In 250,000 years, how can we even begin to predict how our descendants will manage the enriched mines of 2% uranium that they find buried in the Yucca Mountain? It is very possible that we will have developed technologies to clean and recycle these depositories (in the same fashion that COGEMA is able to profit from cleaning up nuclear waste sites today) and that most of these long term safety issues will be eliminated with our exponential increase in nuclear knowledge. However, as confident as we may be in our future knowledge, it is difficult to swallow the fact that by choosing this cheap route, we are burying our problems and taking the gamble that in the future we will be able to deal with it. — Fred