Mixing plutonium with an inert material—”downblending” it—and entombing it at the Waste Isolation Pilot Plant (WIPP) repository near Carlsbad, New Mexico, is the cheapest way to dispose of the surplus US fissile material. So says a recently released report from the US Department of Energy’s National Nuclear Security Administration (NNSA).
The report lists five options for how the US could meet the terms of a 2011 agreement with Russia. Under those terms, the two nations each agreed to permanently get rid of 34 metric tons of plutonium. In its fiscal year 2015 budget request, the Obama administration said that it intends to mothball a half-finished plant being built to transform the US plutonium into mixed-oxide (MOX) fuel for commercial nuclear reactors while it explores potentially less costly routes for disposal over the next 12–18 months (see Physics Today, May 2014, page 18). The plant’s construction cost, estimated in...
