Shape of things to comeNew reactor design lessens risk of weapon proliferation

The increasing price of oil (ignoring, for the moment, the dramatic recent decline in the price per barrel as a result of the troubles in the financial markets) and worries about the environment have led to a renewed interest in nuclear power, after decades of inaction on the that front. There are two problems with nuclear power, though, which will have to be convincingly addressed before it gains more acceptance. The first is what to do with the large amounts of nuclear waste generated in the process of producing power; the second is the risk of nuclear weapons proliferation.

At least with regard to the weapon proliferation issue, Technology Review’s Kevin Bullis writes that MIT researchers, in collaboration with a new research institute in the United Arab Emirates (UAE), have suggested novel designs for nuclear reactors which could decrease the risk that nuclear fuel would be diverted for use in nuclear weapons. Bullis quotes Youssef Shatilla, a professor at the Masdar Institute, in the UAE, to say that when nuclear materials are in use inside a nuclear reactor, they are too hot to steal. The danger comes when fuel is being manufactured, when enrichment facilities can be used to make weapons-grade materials, or when nuclear materials are transported, during either delivery or waste removal. Bullis says that to lessen the first danger, the government of the UAE plans to lease its fuel from other countries rather than make its own fuel. UAE will thus not have the technology to enrich uranium for making nuclear weapons.

What about the second problem? The MIT and Masdar researchers are designing new reactors that would need to be refueled far less often than conventional ones — once every fifteen to thirty years rather than every five years, decreasing the frequency of deliveries and the chances that the materials could fall into the wrong hands. “If you look at how you can divert nuclear material so it can be used in a weapons program, it is when the nuclear fuel is outside of the reactor core, when it’s relatively cool and people can manipulate it,” Shatilla told Bullis. “Our strategy is to keep the fuel inside the core as long as we can.” The new reactors would have the added benefit of producing at least one-third of the waste of existing plants.

For readers with degrees in reactor design: The key is to increase the enrichment level of the uranium-235 used in the core of the reactor from less than 5 percent, which is the level current reactors use, to about 20 percent — which would still not make the material suitable for use in weapons. Now, increasing the enrichment level would require addressing two issues: First, new safety precautions will have to be introduced; second, the fuel will need to be modified to make sure the reactions do not proceed too quickly (otherwise there will still be a need to refuel to reactor frequently).

The researchers note that one more way to lengthen the life of the nuclear material in the reactor is to find a way to turn uranium-238 into fuel (in ordinary nuclear power plants, some of the neutrons released during fission are absorbed by uranium-238, a material that does not undergo the process).