WASTE SUBSTITUTION

7.46 BNFL wishes to operate a system of waste substitution with its overseas reprocessing customers. This would involve the United Kingdom keeping some extra ILW and LLW as a substitute for a very small amount of extra HLW sent back to other countries. The advantage to BNFL's customers is that they would only need to make provision for the management of returned HLW, rather than LLW, ILW and HLW. Instead of a simple substitution based on radiotoxicity and half-life, the formula proposed for calculating how much HLW should be substituted includes the groundwater return time for radionuclides from a repository. This time has been established for LLW using Drigg, but cannot be estimated for ILW in the absence of an ILW repository. In 1995 the Government said that BNFL could begin substitution of LLW but that the ILW should be returned to its overseas customers if a repository (in the UK) is not available at the time when BNFL is contractually obliged to start sending back the reprocessing wastes, ie 25 years after the wastes have arisen[76].

Views on waste substitution

7.47 BNFL told us that waste substitution would increase the United Kingdom's ILW responsibilities by about two per cent, but that HLW would be reduced by four per cent (Q 128)[77]. Substitution would be radiologically neutral to the United Kingdom and there should be environmental benefits because of a 90 per cent reduction in the transport of wastes. BNFL said that they wished to see the linkage removed between substitution and the availability of a repository (P 289). This point was also made in a recent report by the House of Commons Trade and Industry Committee (11th Report, 1998) which said that, "the inability political as well as technical of the UK system to solve the question of ILW disposal therefore threatens to undermine a major export opportunity". The Committee concluded: "it is important that the question of substitution be recognised as having significant trade implications, and as being very much more than a technical or scientific issue".

CONCLUSIONS ON REPROCESSING, PLUTONIUM AND MOX

7.48 Our concern is with the waste management implications of reprocessing. We are convinced that the reprocessing of spent Magnox fuel should continue, because of the difficulties of storing this fuel for long periods and of disposing of it. Reprocessing of AGR and PWR fuel is environmentally neutral compared to direct disposal but reprocessing of this fuel is not valuable as a waste management method unless the separated plutonium can be recycled or re-used.

7.49 The one current use for separated civil plutonium is in the fabrication of MOX fuel. In the much longer term it may be possible to use plutonium in fast breeder reactors. In the United Kingdom our stocks of separated plutonium far exceed the amounts we could use as MOX in our own reactors or that we might wish to keep as a strategic resource for a future fast reactor programme. We have no reactors which can use MOX at present. The amount required as the initial charge in the core of a 1 GW(e) fast reactor is about 4 tonnes; our stocks of civil plutonium could reach over 100 tonnes by 2010.

7.50 There is no reason to continue to store plutonium which is surplus to all foreseeable requirements. Furthermore if any plutonium is to be declared waste it is necessary to know the quantity to be so declared soon, because of its implications for repository capacity and hence site selection.

7.51 We therefore recommend that the Government develops, as soon as practicable, a clear policy on the long-term management of the United Kingdom's plutonium stock. Our view is that this should consist of maintaining a minimum strategic stock of civil plutonium and declaring the remainder to be waste. Surplus defence-related plutonium should be declared formally to be waste and plans made for its long-term management.

7.52 The principal waste management issue raised by the reprocessing of foreign fuel is that of substitution. Our recommendations in Chapter 6 imply that a repository for ILW is unlikely to be available within 25 years from now. Under present government policy on substitution, this would mean that BNFL would probably have to return ILW to foreign customers, rather than substituting HLW. We recommend that Government re-examines this policy in the light of the more recent work by RWMAC and the 11th report of the House of Commons Trade and Industry Committee.

77   A 2 per cent increase in ILW volume represents about 3,000 cubic metres of material, whereas a 4 per cent decrease in HLW represents a volume reduction of about 80 cubic metres (based on figures for 2010). Back