(December 1, 2000) A report commissioned by the UK government questions the future of reprocessing in the UK. Linked to this is the plutonium question. The UK continues to accumulate plutonium from reprocessing spent nuclear fuel, but has no definite plan of what to do with it. One option for BNFL is to build a new PWR at Sellafield designed to run on Mixed Oxide (MOX) fuel. However, a study showed that it is more cost-effective to incorporate the plutonium into "dirty" fuel, which would then be stored as nuclear waste.
(539.5223) WISE Amsterdam - On 14 November, the Radioactive Waste Management Advisory Committee (RWMAC) released its to the UK government on the radioactive waste implications of reprocessing. Up until now, the UK has sent all Magnox and Advanced Gas-cooled Reactor (AGR) spent fuel for reprocessing at Sellafield. The original purpose of reprocessing Magnox fuel was to provide plutonium for nuclear weapons production. With the end of the Cold War, this was no longer a priority. However Magnox fuel corrodes easily in water and is inflammable in air since it contains uranium in metal form with a magnesium alloy cladding. Reprocessing Magnox converts it into a chemically stable oxide form, more suitable for storage, but in the process produces large amounts of radioactive discharges. The B205 Magnox reprocessing plant at Sellafield is responsible for a large proportion of Sellafield's radioactive discharges into the Irish Sea. Under the OSPAR convention, the UK has agreed to halt these discharges, meaning that B205 must be shut, which in turn would mean that no more Magnox fuel must be burned. The remaining Magnox stations would therefore need to close unless an alternative fuel is found. BNFL is considering the use of an oxide fuel ("Magrox") in the two remaining plants, Oldbury and Wylfa. However these plants have other problems (see article in this issue) which may force them to close early.
For the oxide fuel, the situation is different. The Thermal Oxide Reprocessing (THORP) plant at Sellafield was intended to be a commercial venture, providing a reprocessing service for nuclear power plants all over the world. With time, reprocessing has become less popular as an option for dealing with spent fuel. The closure of most fast breeder programs has eliminated one of the justifications for separating plutonium, and the fall in uranium prices has made recovery of uranium from spent fuel unattractive. Reprocessing is expensive, and with increasing competition in the electricity supply industry, many utilities would rather put the spent fuel into storage than reprocess it. This raises a question mark over THORP's future. Some utilities have indicated a wish to curtail existing reprocessing contracts at THORP. Michael Kirwan, finance director of British Energy, has said, "As far as we are concerned, reprocessing is an economic nonsense and should stop straight away". The RWMAC report considered that THORP's currently contracted work could be completed by 2010.
The future of reprocessing depends on the plutonium question: is it a waste or is it a fuel? As at 1 April 2000, the UK's civil stockpiles included 61 tonnes of separated plutonium dioxide. This stockpile continues to increase because of reprocessing. The RWMAC report considered three options for when reprocessing should be stopped at Sellafield: "combined early termination", in which reprocessing is stopped as soon as the committee considered practicable; "combined reference scenario", based on BNFL's business plan, and a "combined extended scenario", based on BNFL's most optimistic business assumption. (BNFL later altered their business plan, though this was not considered to change the conclusions of the report.) For each scenario, the resulting amounts of waste, uranium, plutonium and leftover spent fuel were calculated. The most notable difference between the three scenarios was in the quantities of plutonium. Therefore, a lot depends on whether the plutonium is considered as waste or fuel.
If the plutonium were considered as waste, it would appear as a liability on BNFL's balance sheet, but if it were considered as fuel, it would appear as an asset. BNFL would therefore like the plutonium to be considered as a potential fuel, but the UK's current options for using plutonium as fuel are very limited. The UK has no fast reactors, and the single PWR in the UK, Sizewell B, is not currently configured to burn MOX fuel.
Two reports presented at the Plutonium 2000 conference in Brussels on 9-11 October, organized by the Belgian Nuclear Society, drew different conclusions about the most cost-effective way of dealing with plutonium. Bill Wilkinson, former chief executive of BNFL and now a consultant, looked at two options for dealing with 90 tonnes of plutonium. He compared building 2,400 megawatts of new light-water reactors designed to run on 100% MOX fuel with plutonium disposal using the "can-in-canister" vitrification technique. He found that the MOX route was GBP 1-1.9 billion (US$1.4 - 2.66 billion) cheaper than vitrification. However, a study by Mike Sadnicki and Fred Barker, which considered a wider variety of options, found that the cheapest option would be to use the Sellafield MOX Plant to fabricate "low-spec" or "dirty" fuel. This looks similar to MOX PWR fuel but cannot be used in reactors. Instead, it would be stored as radioactive waste. Sadnicki and Barker said that the "can-in-canister" approach considered by Wilkinson would be the most expensive option.
Sue Ion, BNFL's vice president for operations and technology, said that BNFL's preferred option is to license Westinghouse's AP-600 technology in a larger AP-1000 version, which could be built on the Sellafield site. However it is unlikely that the present UK government would approve construction of new reactors at Sellafield. As for the "dirty" fuel option, some would say that following last year's MOX data falsification scandal, BNFL already has experience in this field!
- Radioactive Waste Management Advisory Committee's Advice to Ministers on the Radioactive Waste Implications of Reprocessing, 14 November 2000 (available on the Web at www.open.gov.uk/rwmac)
- Nucleonics Week, 2 November 2000
- Renew/NATTA issue 128, Nov/Dec 2000