The Radioactive Waste Management Advisory Committee (RWMAC) is the independent body that advises UK Government, including the devolved administrations for Scotland and Wales, on issues relating to the management of civil radioactive waste. This document reports the Committee's 1999-2000 review of the waste implications of reprocessing.

Highly radioactive "spent" nuclear fuel is removed from a reactor after use. In the UK this fuel can come from three types of nuclear reactor used to generate electric power: Magnox reactors, Advanced Gas-Cooled Reactors (AGRs) and the Sizewell B Light Water Reactor (LWR). Two broad management strategies are available to deal with this spent fuel in the short to medium term. It may either be stored in such a way that it does not deteriorate significantly or, after a period of cooling, it may be dissolved in acid and potentially re-usable uranium and plutonium contained within it chemically separated out. The latter is termed reprocessing.

Uranium and plutonium separated from spent fuel by reprocessing can (and successfully have been) used again in nuclear power stations. They may therefore be seen to have "value" in terms of the large amounts of nuclear power that they can potentially generate. But this must be set against the cost of the reprocessing itself. In addition, reprocessing produces a range of wastes the most notable of which is liquid high level, heat generating waste which, again after cooling, is converted to chemically stable, although highly radioactive, glass. Like the process of nuclear power generation itself, reprocessing also gives rise to intermediate and low level solid radioactive wastes and liquid and gaseous radioactive discharges that must be managed. For all these reasons, the economics and benefits of reprocessing are currently the subject of lively debate.

The review of reprocessing that is reported here has focussed on BNFL's activities at Sellafield, the only UK location where reprocessing is carried out at the present time. Both the reprocessing of Magnox spent nuclear fuel in the B205 facility and the reprocessing of AGR and LWR spent nuclear fuel in the THORP facility have been considered. The latter, in particular, also undertakes reprocessing of overseas spent nuclear fuel.

The review has evaluated and assessed the management implications of the waste and other material arisings that follow from a range of nuclear power plant and reprocessing operational scenarios. These were chosen to span early termination of UK reprocessing through to the maximum possible extent of future reprocessing that BNFL could reasonably foresee. RWMAC notes that the early closure of Magnox reprocessing could also necessitate early closure of the Magnox power stations. The wider consequences and environmental implications of replacing these power sources was not evaluated by the Committee.

Inevitably, most of the factual data were supplied by BNFL. The Committee undertook such checks on consistency and accuracy as it could, recognising that a fully independent analysis was not possible. Prior to finalisation of the report, BNFL were asked to vouch for the factual accuracy of the content. I believe that this process has led to new information being put into the public domain, for which the company should be thanked. RWMAC continues to believe that future radioactive waste management policy must be based on full and open disclosure of all the relevant facts. The Committee hopes that its analysis will provide useful background to inform debate of the controversial reprocessing issue as part of the Government's forthcoming radioactive waste management policy review.

Professor Charles Curtis
Chairman of RWMAC

As part of its 1999-2000 work programme, the Radioactive Waste Management Advisory Committee (RWMAC) was asked by Government Ministers to undertake a review of the radioactive waste implications of the reprocessing of spent nuclear fuel. RWMAC's aim in compiling its advice has been to produce an assessment that contributes usefully to the overall policy decision-making process. The Committee focussed its work on reprocessing at BNFL, Sellafield, the only other reprocessing plant in the UK at UKAEA, Dounreay currently being closed and, in any case, only likely to account for a very small percentage of UK reprocessing activity if ever reopened.

Form of study
The way RWMAC chose to conduct its study was to formulate a number of possible future scenarios for the two types of reprocessing undertaken at Sellafield - reprocessing of uranium metal and uranium oxide fuels. The first of these deals with Magnox spent fuel in the B205 facility and the second with Advanced Gas-Cooled Reactor (AGR) and Light Water Reactor (LWR) spent fuel in the THORP facility.

Four individual Magnox scenarios and five THORP scenarios were initially considered. For the purpose of assessing the implications of reprocessing, these were grouped into three combined scenarios aimed to represent: the earliest practicable end to reprocessing (the Combined Early Termination scenario); through BNFL's business plan scenario existing at the time the RWMAC work commenced (the Combined Reference scenario); to BNFL's most optimistic business assumption at that time (the Combined Extended scenario). BNFL were then asked to run analyses of these scenarios using their in-house resources to provide the information required by RWMAC. The Committee vetted the information insofar as it was reasonably able and provided BNFL with the opportunity to vouch for the factual accuracy of a final draft of its report.

As it transpired, BNFL's Magnox business plan was revised in May 2000 during the course of RWMAC's work. The revised plan foresaw a somewhat longer life than previously envisaged for most of the Magnox reactors, and thus a somewhat greater volume of Magnox spent fuel reprocessing, 12,000 as opposed to 10,500 tonnes of heavy metal (tHM, see section 5.1 of main report for an explanation of this term). However, this increase lay within the range of scenarios considered by the Committee. Equally, some of the more recent evidence available to RWMAC suggested that THORP reprocessing prospects now look less bright than when its work began and the THORP assumption contained in its Combined Reference scenario may now be somewhat optimistic.

Main findings and observations
This section summarises the main findings of the RWMAC study. For the purpose of this Executive Summary, key observations and recommendations are denoted by italics.

The reasons for Magnox and THORP reprocessing are fundamentally different. Originally Magnox reprocessing was undertaken to produce plutonium for the UK nuclear weapons programme. More recently it has been seen to be that of converting a reactive and unstable form of spent fuel into materials more suitable for safe storage and, possibly, eventual underground disposal. Conversely, THORP reprocessing was set up as a commercial venture to provide operators in the UK and abroad with a spent fuel management route and/or to extract reusable uranium and plutonium from their spent fuel.

A key element of the Magnox reprocessing debate has been whether or not reprocessing of Magnox spent fuel is necessary. The uranium metal contained in Magnox spent fuel and its magnesium alloy cladding are reactive materials. Once wet stored, it is necessary to reprocess the spent fuel due to corrosion effects. It has been suggested in some quarters that dry storing Magnox spent fuel could remove the need for reprocessing. Having reviewed available evidence, RWMAC has concluded that, at the present time, dry storage cannot be regarded as a practicable option for the longer-term management of Magnox spent fuel. It follows that Magnox spent fuel reprocessing is necessary and that the early termination of Magnox reprocessing would in turn require the closure of the Magnox power stations. However, given its potential sensitivity, it is suggested that the issue of the need to reprocess Magnox spent fuel is one that should be addressed in the Government's forthcoming solid radioactive waste consultation.

The revised Magnox business plan announced by BNFL in May 2000 increased the planned operating lives of the majority of the Magnox power stations. BNFL also indicated that, in light of this revised plan, they expected to be able to close the B205 Magnox reprocessing plant by around 2012. In light of reprocessing throughput performance in recent years, RWMAC has doubts that closure by this date will be possible. RWMAC recommends that BNFL reviews its revised May 2000 business plan statement to ensure that it is realistically commensurate with the closure of B205 by around 2012, to be clear how progress towards this goal will be monitored, and to declare what its strategy would be if the necessary throughput is not achieved.

The lifetime of THORP reprocessing is dictated by BNFL's ability to win commercial contracts for reprocessing either in the UK or abroad. RWMAC's analysis suggests that THORP's currently contracted work could be completed by 2010. Statements made by British Energy to a House of Commons Select Committee on Trade and Industry suggest it will be difficult for BNFL to win new business within the UK. Recent developments abroad suggest that the acquisition of new overseas work will also not be easy. Indeed some utilities both in the UK and abroad have indicated a wish to curtail existing reprocessing contracts although, at the time of preparation of this report, none have actually done so. Hence, whilst the Committee was in no position to judge whether or not new overseas contracts might emerge, it notes the possibility that THORP reprocessing may also be a time limited activity. The Select Committee recommended that BNFL should "address in its corporate plan the prospects of reprocessing over the next four years to the end of the baseload contract period in 2004, and identify the commercial implications of any shift in policy from reprocessing to storage". RWMAC supports the Select Committee's view.

BNFL's May 2000 business plan speculates on the possibility of the lives of the Oldbury and Wylfa Magnox reactors being extended through the use of Magrox fuel. This is a uranium oxide, as opposed to a uranium metal, fuel contained within a stainless steel, rather than to a magnesium alloy, cladding that can be used in a Magnox reactor. Oxide fuels (i.e. Magrox) are inherently much more stable chemically than metallic fuels (i.e. Magnox). Uranium oxide persists indefinitely in the natural environment where it occurs as uranium ores. In contrast, almost all metals spontaneously oxidise. Stainless steel is a metallic alloy which is relatively stable, very much more so than the magnesium alloy used as cladding for Magnox fuel. BNFL envisages that a decision on whether the use of Magrox fuel is feasible will be taken sometime around 2003. Given the possibility of a scenario where it may not be economic to extend the operation of THORP beyond 2010, RWMAC recommends that BNFL looks into the possibility of storing, as opposed to reprocessing, Magrox fuel.

Reprocessing takes spent nuclear fuel and converts it into a range of materials. Some may be deemed more stable than the spent fuel itself, some may be deemed reusable and some may be seen only as waste products. The materials include high level waste (HLW, ultimately, although not immediately, in vitrified form, VHLW), intermediate level waste (ILW), low level waste (LLW), reprocessed uranium (in the form of uranium trioxide, hence RepUO3) and separated plutonium (again in oxide form, hence SepPuO2). These would be held alongside any spent fuel that is not reprocessed, which would also have to be regarded as another form of HLW. Stocks of all these materials already exist and what effectively the reprocessing is doing is varying the future balance between them. Any activity that involves handling radioactive materials, including reprocessing, will give rise to the potential exposure of workers. Reprocessing also gives rise to discharges, both to air and to sea, that results in radiation doses to members of the public. RWMAC sought to address both these issues during the course of its work.

Estimates of eventual UK material holdings for the three combined scenarios considered by RWMAC, including ILW and LLW from all sources, are given in the table below:

	VHLW(m3)	ILW(m3)	LLW(m3)	Uranium oxide (t)	Plutonium oxide (t)	Spent fuel (tHM)
Holdings 4/1/00	720	77,000	6,000	90,000	61	N/A
Total forecast holdings:	885	201,000	1,860,000	99,000	84	4,400--
· Combined Early Termination	1,345	209,000	1,900,000	108,000	115
· Combined Reference scenario	(1,375)	(211,000)	(1,900,000)	(109,000)	119
· Combined Extended scenario	1,495	218,000	1,960,000	117,000	137
Table notes: a. The Combined Early Termination scenario equates to the earliest practicable end to reprocessing, the Combined Reference scenario to BNFL's business plan at the time the RWMAC study commenced, and the Combined Extended scenario to BNFL's most optimistic future reprocessing business assumption. b. The figures in this table have been derived from Table 7 of the main report. The holdings are as of 1 April 2000 and the Combined Reference scenario total forecast holdings come directly from Table 7. The Combined Early Termination and Combined Extended scenario total forecast holdings are estimated on the basis of the relativities to the Combined Reference figures given in Table 7. c. The figures in brackets allow for the additional 1,500 tHM of Magnox spent fuel to be reprocessed under BNFL's revised Magnox business plan. d. The spent fuel figures are exclusive of the 4,100 tHM fuel - 2,900 tHM AGR and 1,200 tHM Sizewell B - that will not be reprocessed under any of the scenarios considered (see section 5.1 of main report).

Note that m3 in the table heading stands for cubic metres, t stands for tonnes and tHM stands for tonnes of heavy metal. All these solid materials need to be managed. RWMAC believes that the Government should be looking to identify a clear and openly-stated policy for the long-term management of all of them through, or in conjunction with its forthcoming solid radioactive waste management review. The figures given in the table show that the different reprocessing scenarios can have marked effects on the amounts of VHLW and spent fuel held. Effects on ILW and LLW are more limited in percentage terms because of arisings from other sources e.g. day-to-day reactor operations and decommissioning.

There would be somewhat less HLW and somewhat more ILW and LLW if the policy of substitution was fully implemented for THORP reprocessing of overseas fuel (where additional HLW is sent back in return for leaving resultant ILW and LLW in the UK). However, the Committee notes that with the demise of the Nirex ILW repository programme, ILW substitution now appears to be debarred. The Government should make clear its current policy on waste substitution, both in respect of ILW and LLW.

A number of bodies have commented on the UK's growing plutonium stockpile - including the Royal Society, the House of Commons Select Committee on Trade and Industry and House of Lords Select Committee on Science and Technology - and whether it should be declared a waste. In particular they have commented on security issues. RWMAC's position remains that there can only be a limited use for the stock in the foreseeable future, and the remainder of the plutonium should be declared a waste unless a credible reason for doing otherwise can be given. In this context, halving the amount held for future strategic purposes would not, in practice, halve the risk or management requirement. RWMAC's main call is for policy clarity in light of reasoned debate of the issues, and hopes this will be included within the Government's forthcoming radioactive waste management policy consultation exercise.

The figures given in the table above only reflect holdings which are UK-owned. BNFL is also required to hold, on an interim basis, products from THORP reprocessing of overseas spent fuel that are required to be eventually returned to the owner. RWMAC believes that there is a lack of transparency in respect of the amounts of such holdings and the timescales to which they are returned. Even the UK Radioactive Waste Inventory makes no such distinction. Extant Government policy is that "the wastes resulting from foreign spent fuel should be returned to the country of origin, and the HLW should be returned as soon as possible after its vitrification". RWMAC recommends that, in future, there should be greater transparency concerning holdings of overseas material within the UK and the proposed schedule for, and progress made towards, their return. Future UK Radioactive Waste Inventories should also distinguish between UK and overseas-owned holdings.

The table shows that the effects on uranium holdings of the three combined scenarios considered are also relatively limited in percentage terms because of the volume of existing holdings. Effects on plutonium stocks are more marked, with eventual holdings being of the order 84, 115 and 137 t for the Combined Early Termination, Combined Reference and Combined Extended scenarios respectively. For the Combined Reference scenario, adjusted to take account of BNFL's revised Magnox business plan, the eventual UK plutonium holding would be of the order 119 t. Note that these are plutonium oxide weight figures.

An area where RWMAC would like to see improvement is in the promotion of passive storage or passivity. RWMAC takes the concept of passivity to be broadly the holding of radioactive material in a passively safe form with a minimal need for active control systems or human intervention. A key emphasis is on the waste form, which should be immobile, physically and chemically stable and resistant to significant deterioration or reaction over a reasonably foreseeable storage period. But the requirements for its storage surroundings are also important. However, the Committee acknowledges that this is not a simple issue. For instance, the advantages of materials processing need to be balanced against the possibility of foreclosing future management options. Nevertheless, the possibilities for developing an operational definition of passive storage, or passivity, that can be used as a yardstick for operational performance, should be given careful consideration.

In this context in particular, RWMAC sees reduction of Highly Active Liquor (HAL) stocks to buffer levels to be extremely important. The Nuclear Installations Inspectorate (NII) have set BNFL a target of 2015 for the achievement of this. RWMAC is concerned, like the NII, that the need for extended reprocessing scenarios could prejudice even this target given past Waste Vitrification Plant performance. The Committee therefore recommends that progress towards this objective of HAL stock reduction is kept under close review and publicised on a year by year basis.

RWMAC has also considered the potential impacts of the radioactive waste discharges associated with Magnox and THORP reprocessing. For this purpose, RWMAC asked BNFL to estimate the discharge activities, critical group doses and collective doses for representative throughputs of 1,200 tHM for Magnox reprocessing and 1,020 tHM for THORP reprocessing per year using their in-house models. These throughput rates are considerably higher than the rates that have actually been achieved in recent years, so may be considered to produce upper bound estimates. They are also for ongoing (i.e. potentially avoidable) activities, taking no account of the effects of historic radioactivity in the environment.

The indicative estimates produced suggest that, at the throughput rates considered, ongoing Magnox reprocessing contributes about 30 and 10 microsieverts per year respectively to the liquid and aerial discharge critical group dose. The corresponding figures for THORP are 5 and 30 microsieverts per year respectively. These are in the context of estimated liquid and aerial discharge critical group doses for all ongoing processes on the Sellafield site, again excluding historic effects, of about 50 and 80 microsieverts per year. However, critical group doses from historic concentrations of radionuclides, notably actinides, in the environment, as a result of past reprocessing activities, may be several times these levels.

The results have been considered in light of the Government's proposed strategy for meeting its OSPAR convention obligations set out in its UK Strategy for Discharges 2001-2020 Consultation Document issued in June 2000. Initial Committee impressions are:

• the objective of ensuring that by 2020 no member of the public should be exposed to a dose of more than 0.02 millisieverts (20 microsieverts) a year as a result of authorised discharges is challenging but potentially achievable, given that doses from historic radioactivity are not included, the Calder Hall reactors close to time in 2006-8 and the currently anticipated Sellafield reprocessing programme is not substantially extended

• in terms of seeking to reduce the activity of discharges, the situation is somewhat more complex. Again, it is difficult to see how any significantly extended reprocessing programme could be compliant with the Government's proposed OSPAR objectives unless substantial advances in abatement technology can be achieved. This brings its own problems, and there currently remain unresolved issues in respect of the ongoing technetium abatement development programme

• the information supplied to RWMAC indicates that it will be difficult to achieve the specific objective of reducing technetium-99 discharges from reprocessing to 10 TBq by 2006. The Committee therefore believes that progress towards this objective needs to be kept under particularly close review

The above suggest a number of potentially important issues that BNFL might consider to be key indicators of their future performance:

• progress with Magnox reprocessing so as to allow closure of B205 by around 2012
• progress towards the achievement of passive storage of materials (assuming a suitable operational definition can be agreed with the regulator)
• progress with the reduction of HAL stocks;
• progress with the return of products from overseas reprocessing;
• progress with reducing discharges so as to meet the UK's OSPAR objectives (including identification of needs and progress towards development of any necessary abatement technology)
• explanation as to how any new THORP contracts will be allowed for in this overall picture (given, for example, that it could place additional pressure on vitrification lines and add to or extend discharges).

Clear and specific annual reporting against these key issues by BNFL is recommended by RWMAC

Finally, RWMAC notes that any discussion and decision on the future of reprocessing in the UK will inevitably given rise to complex social and political issues some of which have been highlighted, although not evaluated, in the latter part of this report.

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