RWMAC's Advice to Ministers on the Radioactive Waste Implications of Reprocessing

ANNEX 5

THE MAJOR SELLAFIELD MATERIALS CONDITIONING PLANTS

Figure A5.1 shows the major Sellafield radioactive waste conditioning and storage plants and their relationship with the site’s reprocessing plants and historic arisings. The plants identified in the diagram are only a proportion of all the plants and facilities located on the Sellafield site.

In practice, the materials arising from Magnox and THORP reprocessing pass through a range of treatment and packaging plants before passing to conditioned storage. It is important to recognise that a variety of historic wastes also pass through these treatment and conditioning plants.

The main treatment and conditioning plants shown in Figure A5.1, together with BNFL’s views of their capacity are as follows:

Highly Active Liquor (HAL) storage. The subject of one of the three recent NII reports. Historic arisings are stored in the HAL storage tanks, which also act as a buffer for reprocessing arisings. BNFL are committed to reducing HAL stocks to buffer levels by 2015 under a regulatory direction from the NII (see Section 6.1).

Waste Vitrification Plant (WVP). Transforms HAL into vitrified blocks suitable for long-term storage. There are two vitrification lines currently running with a third to come on stream later this year. All three are required to meet BNFL commitments on reducing historic HAL stocks. Capacity and throughput is a crucial issue due to BNFL commitments to reduce historic stocks of HAL to the timescales required by the NII (see section 6.1). During the course of the reported study, BNFL indicated to RWMAC that a fourth line would be necessary to reduce HAL stocks to appropriate buffer levels by 2015 in the case of the Combined Extended scenario.

Magnox Encapsulation Plant (MEP). A facility for the immobilisation of Magnox swarf and other historic ILW arisings. Cement grout is used to immobilise the swarf and smaller quantities of other ILW arisings into single-skinned stainless steel drums. Currently services Magnox and historic arisings. BNFL state that there are no capacity issues related to differences in material arisings in this study’s reprocessing scenarios.

Wastes Encapsulation Plant (WEP). Encapsulates various forms of solid and sludge ILW wastes. Currently services THORP and soon historic arisings as well. BNFL have stated that there are no reprocessing capacity issues in the longer term, although the plant is closely coupled to reprocessing output and therefore short term production outages in this plant may affect reprocessing throughput. Plant throughput will increase over next few years to treat arisings from the new Sellafield Drypac plant that will recover historic wastes.

Waste Packaging and Encapsulation Plant (WPEP). Encapsulates mainly floc arisings from the treatment of discharges. Currently services both reprocessing plants and also treats historic arisings. The plant has its own large store compatible with other Encapsulated Product Stores on the Sellafield site (see Annex 6). BNFL state that there are no reprocessing capacity issues.

Waste Treatment Complex (WTC). Currently treats all PCM (Plutonium Contaminated Material) waste arisings on the Sellafield site plus also historic arisings e.g. from Drigg retrievals. BNFL state there are no reprocessing capacity issues.

Box Encapsulation Plant (BEP). Treats large items of miscellaneous historic waste. Not yet in service. Although the plant has no direct link to reprocessing it does have its own large store which is compatible with other Encapsulation Plant Stores.

A discussion of the storage facilities shown in Figure A5.1 is given in Annex 6.

Figure A5.1.1 Schematic diagram of major sellafield waste plants