How much will it cost to destroy stockpiled US plutonium?

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 2007 at $4.8 billion, has ballooned to $8.7 billion.

The NNSA report estimates that combining the plutonium with materials to inhibit reuse and storing the mixture permanently underground would come to $8.8 billion over the lifetime of the operation. By comparison, the projected lifetime expenditures for converting the plutonium to MOX fuel would be $25.2 billion. The estimates include both capital and operational expenses, plus costs for preparing the plutonium metal. They do not include funds already spent. The downblending option was based on the assumption that the geological repository would be WIPP, the sole US facility licensed for permanent disposal of transuranic wastes. Building an alternate disposal facility would obviously cause the option’s cost to mushroom, the report acknowledges.

Senator Lindsey Graham (R-SC) has led congressional opposition to halting construction of the MOX facility, located at the Savannah River Site in South Carolina. Graham insists that there is no cheaper alternative to MOX that will allow the US to meet the 2018 timetable of its agreement with Russia. And he and other lawmakers have noted that changing the disposal method would require renegotiation of the terms of that agreement.

In May the House passed a FY 2015 defense authorization bill that would require the MOX plant construction to continue. The same requirement was included in the version of the bill approved by the Senate Armed Services Committee later that month. The Senate measure also added $145 million to the $196 million the administration had requested to put the half-completed project in standby condition. The House version of the appropriations bill that funds DOE also would require that construction continue.

“Now is not the time to change course on the MOX program and try to renegotiate anything with the Russians,” Graham said in a statement issued after committee approval of the bill. He has promised to work with project contractors to bring costs down.

Rose Gottemoeller, the State Department’s undersecretary for arms control and international security, said that despite the heightened tensions with Moscow, she believes Russia would agree to negotiate a change in the method of disposal if the US requested it. “The Russians have an interest in seeing those 34 tons of US plutonium gone, so my view is that they will work with us,” she said in remarks on 13 May.

The three other plutonium-disposal options considered in the NNSA report are irradiation in fast reactors, estimated to cost $50.4 billion; mixing with nuclear waste and glassification, estimated to cost $28.6 billion; and deep borehole disposal, for which no estimate was prepared. Russia has chosen the fast-reactor route for disposing of its plutonium.

A DOE inspector general’s audit released on 22 May blames the project’s escalating costs and schedule slippages on a combination of an “immature design,” understating the difficulty of installing “various construction commodity items,” and high personnel turnover. When approved for construction in 2007, the MOX plant was expected to be finished in 2016. According to the inspector general’s report, if construction isn’t halted as the administration wants, the plant won’t be completed until 2019.