In its recently published paper ‘Oxide Fuels – Credible Options’, November 2011, the United Kingdom's Nuclear Decommissioning Authority (NDA) sets out options for the future operation of Sellafield’s Thermal Oxide Reprocessing Plant THORP. Opened in 1994 to reprocess UK’s domestic Advanced Gas Cooled (AGR) fuel and Light Water Reactor (LWR) fuel from overseas customers, the plant is currently operating years behind schedule. An estimated 400 tons of overseas spent fuel that should have been completed around 2004, plus some 2000 tons of UK AGR fuel remains to be reprocessed.
In addition, a further 4000+ tons of spent AGR fuel (including the currently expected lifetime arisings from the UK’s fleet of AGR power stations) are destined either for long-term storage at Sellafield prior to disposal or for reprocessing – at the NDA’s discretion. Should 5-year extensions be granted to the AGR power stations, a further 900 tons of spent fuel would arise.
A November 24, CORE Briefing provides a summary of the NDA’s assessment of three Options for THORP: - 1- Complete THORP’s reprocessing contracts; 2- Close THORP early by reprocessing less than the contracted amount of spent fuel and 3- Extend THORP operations so that more than the contracted amount of spent fuel can be reprocessed.
From its assessment, the NDA has concluded that, in line with its 2011 Strategy, Option 1 is the most viable and cost-effective - with the proviso that ‘additional new and costly infrastructure can be avoided (this would include the installation of new High Level Waste tanks), and that NDA proposals for the interim storage of AGR fuel are themselves viable. After further work to underpin the strategy, and providing the provisos are met, the NDA expects to confirm Option 1 as its preferred strategic option by summer 2012.
NDA currently rejects Option 3 – extending THORP operations to include more AGR fuel being reprocessed than currently contracted, and potential new business from domestic and overseas customers ‘if there were any’ – because:
- extended reprocessing would require multi-billion pound investment across a wide range of infrastructure at Sellafield, with major capital build projects required to support THORP’s extension beyond 2020. Such investment would divert finite resources from the NDA’s primary role of risk and hazard reduction at Sellafield, and new capital build projects would result in energy use and carbon emissions.
- extended reprocessing could potentially impact on the UK’s discharge commitments under the OSPAR treaty and could challenge the alpha and tritium target levels under the UK’s own Strategy for Radioactive Discharges.
- no interest has been expressed by the potential operators of new-build reactors in the UK to have their spent fuel reprocessed and recycled. Even had they done so, bulk quantities of spent fuel would be unlikely to be ready for reprocessing until the mid-2030’s when THORP and associated facilities would be over 40 years old.
The NDA’s current rejection of closing THORP early under Option 2 is based on:
- the provision of additional storage capacity for AGR fuel at Sellafield to ensure that incoming fuel from the power stations – at around 180 tons/yr - can be managed
- the possible need to implement alternative arrangements for overseas fuel.
- the requirement to manage spent fuels that are more susceptible to corrosion during storage
- the resultant earlier reduction to the workforce – though this could be mitigated by redeploying workers to the high hazard reduction activities elsewhere on site.
However, the NDA nevertheless believes that the early closure option should continue to be examined because of concerns that should a number of performance risks associated with THORP and its support facilities arise, Option 1 might have to be abandoned before 2018.
These risks include the overall age and condition of the reprocessing infrastructure, further failures of Sellafield’s current suite of Evaporators which process the high level wastes produced by reprocessing – or a delay in bringing on-line of a new Evaporator in 2014/15 – and the viability of the plans to store AGR fuel. The success of these storage plans depends on the current program to remove redundant multi-element bottles (MEB’s used to transport overseas fuel that has now been reprocessed)) from the ponds being completed on schedule, and the ponds suitably dosed with a corrosion inhibitor.
Based on THORP’s 2018 closure, an application to the Local Authority for a change of use of the ponds from buffer storage prior to reprocessing to interim storage pending disposal is expected to be made around 2016. Subject also to Regulatory approval, the NDA believes a technical and safety case for both storage and disposal of AGR fuel can be made.
In promoting what is likely to be its preferred Option 1, the NDA says that by completing THORP’s contracts in 2018, it will have honored obligations to overseas customers (and inter-Governmental treaties); provide time to prepare facilities for the interim storage of AGR fuel and create space to receive and manage all fuel arisings from AGR stations. It would also enable fuels susceptible to corrosion to be reprocessed.
The NDA believes the costs of the next 7 years of reprocessing - taking THORP to a 2018 closure - are comparable to those of the storage and direct disposal of spent fuel – largely because the capital costs for the reprocessing infrastructure are already sunk. If this had not been the case ‘it would be more cost-effective to cease reprocessing early’.
As part of its Oxide Fuels Credible Options paper, the NDA was asked by Government to consider the wider impacts of its THORP closure decision on the potential for future reprocessing in the UK. Reviewing topics that included Fast Breeder Reactor prospects, the future use of plutonium and new-build reactor operations, the NDA concluded that the timing of THORP’s closure had little material impact on any potential future requirement to supply plutonium; that THORP’s closure would neither impact on the UK’s new-build program nor on the long-term potential for reprocessing in the UK. Should the latter be required, a new reprocessing plant would be necessary.
It also concluded that, on a like for like basis, spent fuel storage followed by disposal ‘is currently more cost-effective than reprocessing’. This was based on an anticipated rise in costs of reprocessing and MOX fuel production in the UK, and the currently low price of uranium. Not surprisingly, all cost data was omitted from the NDA’s paper on the grounds of commercial confidentiality.
Plutonium re-use - putting the cart before the white elephant. Unwilling or incapable of learning from the UK’s disastrous MOX fuel experiences, the December 1 Government approval for the re-use of plutonium as MOX fuel is branded by CORE as a ‘decision made in the dark that yet again puts the proverbial cart before the inevitable nuclear white elephant’. With a preliminary decision taken by Government even before its Department of Energy and Climate Change (DECC) public consultation on plutonium management had started, it nevertheless promised that final approval for the re-use option was conditional on a range of major issues – including costs and demand for MOX fuel - being tested ‘before the UK Government will be in any position to take a final view'. (emphasis added)
The weakness of its case for the re-use of plutonium as MOX fuel has undoubtedly prevented the Government from going ‘the whole hog’ and putting its weight behind the construction of a new MOX plant at Sellafield or elsewhere in the UK. In its document published December 1 ‘Management of the UK’s plutonium stocks - A consultation response on the long-term management of UK-owned separated civil plutonium’ the Government however suggests that the construction of a new MOX plant could begin around 2019 with the first MOX fuel being fabricated in 2025.
On August 3, NDA decided to close the Sellafield MOX Plant SMP, a total failure which has so far cost the taxpayer BP1.4 bn (US$2.18 bn or 1.67 bn euro). (see Nuclear Monitor 732, 8 September 2011)
CORE Press Release, 2 December 2011
Source: CORE Briefing 3/11, 24 November 2011
Contact: Martin Forwood at CORE (Cumbrians Opposed to a Radioactive Environment). Dry Hall, Broughton Mills, Broughton-in-Furness, Cumbria LA20 6AZ, UK.
Tel: +44 1229 716523