One year after it was forced to shut down following a major accident (20th April 2005), Sellafield’s Thermal Oxide Reprocessing Plant (THORP) remains idle and facing a series of major hurdles before any restart is possible. An original restart date of December 2005 has been retarded a number of times and now stands at ‘Summer 2006’, though no official decision has yet been made on whether the plant should re-open at all.
Given the complexity of the technical and regulatory hurdles still to negotiate – particularly the work to repair the plant’s damaged Cell – the NDA’s projection of Summer 2006 appears highly unlikely to be met, by at least six months and extending THORP’s closure to two years or more.
The plans to repair and restart THORP this summer, formulated by contractors British Nuclear Group (BNG) and approved by the NDA, have been heavily criticised in a report by an independent consulting engineer who has scrutinised the NDA’s latest technical assessment of the repair plan . In his own report published on 13th April, John Large, of Large & Associates, describes the repair plan as ‘an expedient compromise at best and, at worst, an engineering bodge’. He concludes that a further 12 months or more of work can be expected before THORP might be in a position to restart.
CORE’s Martin Forwood said today. Without cutting corners, THORP is unlikely to re-open until next year at the earliest. A two-year closure has major implications for the continued operation of British Energy’s (BE) power stations which, in order to keep running, depend on pond storage space being available at Sellafield for their reactor fuel. With no reprocessing whilst THORP is closed, that storage space is already running out”
British Energy (BE) operates seven Advanced Gas Cooled Reactor (AGR) power stations which, between them aacount for around 80% of the UK’s nuclear generated electricity. With little spare storage capacity in their own fuel ponds , they routinely send their fuel to Sellafield by rail. Deliveries have continued at a rate of at least one transport of spent fuel per station per week since the THORP accident. At Sellafield, the fuel is stored in any one of three separate storage ponds which the NDA admits has, between them, around one year’s worth of spare capacity. With THORP already closed for one year, power station deliveries have already taken up much of that spare capacity.
Having previously flagged up AGR fuel storage as a problem, the NDA has reacted to the worsening storage situation by ‘accelerating’ plans to create more pond space via a number of separate measures. These include optimising existing pond space by removing surplus pond equipment; ordering new ‘skips’ to contain arriving AGR fuel; and by clearing from ponds the estimated 1000+ redundant and empty Multi Element Bottles (MEB), used originally for delivering overseas fuel to Sellafield and currently taking up much needed pond space.
Martin Forwood added “ Realistically, there is nothing much the NDA can do to accelerate these plans which are.very much a case of too little too late. The industry’s oversight in catering for an eventuality such as this is mind-boggling”.
Of the measures initiated by the NDA, the removal of the MEB’s offers the greatest scope for creating extra space. However, BNG’s plan to move the MEB’s to a new store to be built alongside THORP only received planning consent this February and is not expected to be in operation until the end of the year at the earliest. Even then, with little over 100 MEB’s per year scheduled to be removed from THORP ponds, storage space for incoming power station fuel will be increasingly problematic.
The repair of THORP’s Feed Clarification Cell, where 83000 litres of dissolved reactor fuel and nitric acid leaked from a fractured pipe, involves by-passing the damaged pipework and its associated accountancy tank and using instead the Cell’s second tank and pipe system. The inability to physically check the second system because of the dangerously high radiation levels within the Cell will make it impossible to guarantee that this alternative ‘route’ is safe and fit for use. With just one accountancy tank in use, the NDA has confirmed that any future throughput in this section of THORP will be reduced to around 40% of the original design figure – from 7 tonnes to 3 tonnes per day, and that verification of fissile materials (including plutonium) will require a different methodology.
Warning that there can be no compromise over nuclear safety or proliferation issues at THORP, John Large considers it very doubtful that the repair selected by BNG will fully satisfy the safety case required by the NII or the prerequisites of fissile material safeguards required by Euratom inspectors. Whilst NII have yet to receive from BNG an application to approve the repair, the nuclear inspectors have already listed 49 safety improvements that must be complied with before any restart is possible. Additionally, NII has served a Specification (a legal requirement to take action) on BNG to ‘halt the commencement of specified THORP operations without consent of the Executive’.
The overall costs of the accident, which will be picked up by the taxpayer via the NDA, are still being calculated. The NDA is recently quoted as putting them at around £50M , though this is unlikely to be the final figure that it intends to claim for the accident under a commercial insurance policy. This despite the fact that, with prosecutions imminent from the Health & Safety Executive (HSE), the magnitude and duration of the spillage, which occurred over a 9 month period, resulted largely as a result of negligence by workers – as confirmed by BNG’s Board of Investigation . In addition to prosecution by HSE, the NDA has confirmed that it will be penalising BNG for failing to safely meet obligations and conditions of their contract to operate THORP.
Martin Forwood said “ THORP can never again operate as originally designed and its safety cannot be guaranteed. Official support for restart smacks more of saving face in the eyes of customers and competitors than any need to reprocess fuel again. To re-open this costly white elephant will be a dangerous and retrograde step and a gross misuse of public money. CORE will continue to urge for its permanent closure and for all spent fuel to be dry stored rather than reprocessed”
Further Notes for Editors.
Dry storage of AGR fuel is a recognised alternative to reprocessing, and one historically preferred by BE. A BE press release (13.11.01) stated ‘given that there is no technical requirement to reprocess AGR fuel, and that storage would be considerably cheaper … there should be a moratorium on the reprocessing of AGR fuel’.
BE’s reactors have a combined generation capacity of some 9000MW whilst, by contrast, the capacity of the remaining four older magnox power stations now owned by the NDA is around 2000MW.
THORP had completed 12 years of operation and was already running some 3 years behind schedule at the time of the accident. As at April 2005 THORP has reprocessed a total 5729 tonnes of fuel out of a total of 7000 tonnes which should have been completed by 2004. The outstanding balance of 1271 tonnes consists of 700+ tonnes of overseas fuel and some 500 tonnes of AGR fuel. Further AGR fuel and a small amount of overseas fuel remains to be reprocessed under ‘second ten-year’ contracts.
The NDA sees THORP’s future revenues, put at £575M for the current year (had the plant been operating), as helping offset the costs of cleaning up Sellafield which have spiralled to an estimated £40Bn. The NDA has confirmed that reprocessing revenue is just one of seven business elements that make up the £575M total.