A year-long Energy Department reexamination of how to get rid of 34 tons of surplus weapons plutonium affordably, as part of a disarmament deal with Russia, has concluded what many experts long suspected: The cheapest option is to bury it, according to the study’s newly-released text.
The study led by John MacWilliams, a Boston lawyer and equity investor appointed to advise Secretary of Energy Ernest Moniz, was inspired by a large increase in the estimated cost of building a new plant in South Carolina meant to turn the plutonium into nuclear fuel.
The plant’s estimated cost in 2007, when construction began, was $4.8 billion. But the 201-page report, released April 29 on the Energy department’s website, forecast that completing and running the plant would cost another $25 billion. When added to the money already spent on the project, called sunk costs, this sum would bring the overall pricetag to $31 billion.
An alternative approach — involving “downblending” or mixing the plutonium with a chemical called an “inhibitor” to make it harder to use in a nuclear weapon and then burying it in deep salt caverns in New Mexico — would cost just $8.78 billion in new spending, according to MacWilliams’ report. Including sunk costs — such as the pricetag of the existing cavern storage facility — would bring the bottom-line cost to over $16 billion, the report said.
Energy officials weren’t immediately available for comment. But downblending was the cheapest of the options studied, the report said, as well as the easiest to accomplish using existing technology.
The report does not describe the chemical inhibitor involved. But the Energy Department has developed a classified substance called “stardust,” a spokesman told the Center, that binds so tightly with plutonium it can’t be extracted without a chemical separation plant.
Energy engineers have already used “stardust” to dilute some plutonium at Savannah River and disposed of the mixture at the Waste Isolation Pilot Plant in New Mexico, the Center reported in 2013.
Downblending faces legal, regulatory and political hurdles, the MacWilliams report noted, and would require modifying the United States’ current plutonium disposal agreement with Russia. But assuming those hurdles could be overcome, the report said the burial of downblended plutonium at the Waste Isolation Pilot plant could begin in just five years.
Although the Energy agency has been working on the Savannah River fuel plant for more than a decade, the new study noted that Energy officials still haven’t found any electric utilities willing to buy the fuel — a mixture of oxides of plutonium and uranium called MOX — the plant is supposed to produce.
The White House put the project, located at the Energy Department’s former weapons plutonium production facility at Savannah River, on “cold standby” last year, slowing construction pending MacWilliams’ review.
South Carolina has filed a lawsuit seeking to force the federal government to complete the MOX fuel plant, where about 1,600 workers are currently employed. South Carolina’s Congressional delegation has long championed the project, led by Sen. Lindsey Graham, R-S.C.
The United States and Russia first signed a deal to each dispose of 34 tons of their weapons plutonium back in 2000, in a pact brokered by Moniz, then working for the Energy department. But the Russians chafed at the United States’ insistence that they not be allowed to use their plutonium to fuel “breeder” reactors that can produce more plutonium than they burn.
The Obama administration in 2010 signed a revised agreement granting Russia the right to use breeders for the program, and locking the United States into turning its own plutonium into fuel rather than directly disposing of it through burial or similar means.
The MacWilliams study looked at three alternatives to the MOX project besides downblending.
One was burning the plutonium directly as fuel in a new purpose-built reactor, probably at Savannah River. Another was “immobilizing” the plutonium by mixing it with highly-radioactive liquid wastes and molten glass in thick metal containers, then storing them. The third was dropping canisters of plutonium into three-mile deep boreholes, where they would nestle among the Earth’s crystalline basement rock.
Building a new plutonium-burning reactor, not surprisingly, was the most expensive option. The study said it could cost more than $50 billion to dispose of the surplus plutonium in this way. With sunk costs the bottom line for this option was $58 billion, the report said.
Mixing the plutonium with high-level waste and glass before disposal, the study found, would cost $28.7 billion — about the same amount of money that it would take to complete the MOX plant. This alternative was favored by many nonproliferation experts during the Clinton administration, and was extensively studied. The bottom line total would be $36 billion, with spending-to-date included.
Some advocates of this approach had hoped it would prove much cheaper.
The report said not enough research has been done on the deep borehole idea to estimate the costs.