UK chooses to reuse Pu

In February 2011, the UK government published a consultation about its plans to deal with 84 tonnes of separated plutonium (it currently holds 112 tonnes; 28 tonnes belongs to foreign utilities). The department of energy and climate change (DECC) considered three management options: continued long-term storage, immobilisation and direct disposal, or reuse of plutonium as mixed-oxide (MOX) fuel. It selected reuse as a preferred option over the previous policy of long-term storage, and reaffirmed its decision in December after reviewing 100 comments from a February-May consultation.

The government said that converting the stockpile into MOX is the ‘most credible and technologically mature option for reuse.’ Any plutonium that cannot be converted into MOX will be immobilised and treated as waste for disposal, it said.

The decision will require a new MOX facility, after the UK government decided to close the nine-year-old Sellafield MOX Plant because of production problems. SMP has produced just 15 tonnes of MOX fuel assemblies, compared with 560 tonnes expected in a 10-year working life, according to DECC. But the government says that lessons from SMP and overseas experience ‘gives confidence that any new MOX plant will be successful.’

An indicative DECC timeline, should the government continue with the idea, sees procurement start in 2015, construction from 2019 and operation from 2025. MOX fuel use in civilian reactors could start as soon as 2029. However, the UK’s new-reactor approval process, the Generic Design Assessment, currently underway for the Westinghouse AP1000 and Areva EPR reactors (expected to start up before 2025) specifically excludes the use of MOX fuel.

Both Areva and Westinghouse spokesmen said that only minor modifications would be required to burn a core with up to roughly 40% MOX. However, Westinghouse points out that significant safety case work would need to be done to make the change.

One prospective nuclear new-build utility has reacted particularly negatively to the proposal. NuGen, a consortium of GDF Suez and Iberdrola, aims to develop a 3.6 GW nuclear power station close to the Sellafield site in Cumbria. It said: “It is vital that … the existing facilitative framework for nuclear new-build is not re-opened or distracted by the potential for MOX use.” It made the statement in its response to the government consultation.

Alternative

Beyond the store/bury/burn options, other possibilities suggested in the consultation include the use of metallic fuel in LWRs, the use of thorium-plutonium fuels, a pebble-bed reactor, and a sodium-cooled fast reactor that burns plutonium as metal fuel.

In its December report on the consultation, DECC described these options as ‘pioneering technology’ and said that given that MOX is proven (in France, anyway), the government does not need to bear the associated development risk of first-of-a-kind designs. However, it also said that the government would be willing to consider such a proposal if a commercial partner was willing to bear the risk, and could demonstrate the delivery of a solution within a similar timeframe to a MOX plant. The Nuclear Decommissioning Authority (NDA) is permitted to borrow up to GBP 2 billion a year, according to the Energy Act of 2004 and would be able to enter into a private finance initiative with approval from the DECC secretary of state. An innovative financial model could therefore be applied for one of the more pioneering designs, or perhaps even a MOX facility.

One potential partner has already stepped forward. GE Hitachi Nuclear Energy has proposed its PRISM sodium-cooled fast reactor, whose technology is based on the EBR II fast reactor at the USA’s Argonne National Laboratory, to burn the plutonium. The company has also gathered a consortium (Costain, Arup and Poyry) to develop the concept for the UK and says it is working with an un-named utility. PRISM was part of GE’s GNEP Advanced Recycling Centre project that included an electrorefining plant, although that plant is not part of this proposal because the design is US government-owned.

GEH is also willing to invest. Earlier this year, GEH took a majority stake (51%) in the project to build a new reactor (an ABWR) at Lithuania’s Visaginas site. When asked about this project structure in September, Danny Roderick, GE’s senior vice president, new plant projects, told NEI that such a model ‘was necessary for some projects,’ but added that it was not something the company liked to do routinely.

In a press conference in December, Roderick said that a PRISM reactor at Sellafield could irradiate the plutonium to make it proliferation resistant in five years, significantly quicker than the 30 years required for a MOX fuel plant. After five years the PRISM plant could start reusing the irradiated fuel for electricity generation. “One of the things that came out of the discussion is that the UK government is looking for the quickest solution because the security cost on the plutonium is very expensive,” Roderick said. He also said that the cost of building a two-unit 600MW PRISM facility would be similar to building one of its LWRs. (Costs of the cancelled South Texas ABWR project, per reactor, had reportedly risen to almost $7 billion in 2010, according to Platts).

The cost of continuing to store plutonium at Dounreay until 2075 and Sellafield until 2120, in line with the previous policy, would be about GBP 8 billion ($12.5 billion), according to the NDA. According to DECC, immobilising and disposing the plutonium would cost GBP 5-7 billion, depending on the technology. In contrast, building and operating a new MOX facility would cost GBP 5-6 billion.

DECC said that reaching a final decision on whether reusing separated plutonium through MOX will take several years. In the meantime, DECC and the NDA will gather information about the market for MOX fuel, and the cost and timescale for procurement of a MOX facility.

This article was first published in the January 2012 issue of Nuclear Engineering International magazine