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UKAEA  Dounreay  today  launches the consultation phase about its change in reference  strategy  for  conditioning  liquid  wastes that are a legacy of reprocessing fast reactor fuel at Dounreay.

A  newsletter  being  issued  to  over  800  organisations  and individuals explains  the  background to the issue and sets out the process for seeking their views.

Fuel  irradiated  in  the  UK’s  Prototype  Fast Reactor was reprocessed at Dounreay  until  1996  to separate the waste, or fission products, from the re-usable  plutonium and uranium. The waste was extracted in the form of an acidic  liquor,  or  raffinate,  and  approximately  200m³  accumulated  in underground  tanks,  where  it  continues  to be stored safely and securely today.

Historically,  the  waste  required  artificial  cooling,  meaning  it  was classified   as   high-level   waste   in   accordance  with  national  and international definitions, and UKAEA’s reference strategy was to vitrify it as blocks of glass. The waste has decayed since reprocessing ceased in 1996 and  now  no  longer  requires  artificial  cooling.  This  means it can be reclassified  as  intermediate-level  waste and conditioned in cement on an earlier timescale.

UKAEA  Dounreay  has  now  changed its reference strategy for managing this waste   from   vitrification   to   cementation.  This  would  involve  the construction  of  a new plant to condition this waste in drums of cement to make it safe for long-term storage or disposal as intermediate-level waste.

The consultation phase of this change in reference strategy is divided into two stages:

• Panels of stakeholders meet in June to review the technical assessment carried out by UKAEA.

• Reports of the panels’ findings, together with UKAEA’s technical assessment, are published as part of a 12-week period of public participation.

Norman  Harrison, director of UKAEA Dounreay, said: "The raffinate from the reprocessing  of  fast  reactor  fuel  accounts  for nearly half of all the radioactivity  in  our  waste inventory at Dounreay, so its conversion to a solid form that can be stored safely and securely in the longer term is one of our highest priorities.

"The  knowledge  that the raffinate can be cemented on an earlier timescale than  vitrification,  using  tried and trusted technology, is potentially a significant   breakthrough   in   the  accelerated  delivery  of  the  site restoration plan. We recognise, however, that such a change in strategy for one  of  the  most significant waste streams and its reclassification is of interest  to  a wide range of stakeholders. We now want to test the work we have  carried  out  so  far  by  submitting  it  to  stakeholders for their
examination and comment."

Notes
1.    Dounreay was Britain’s centre of fast reactor research and development from 1955 until 1994. Three nuclear reactors, fuel  reprocessing and other associated nuclear facilities were built and      operated on a 140-acre site. The site is now being decommissioned at an estimated total cost in the region of £4 billion. The decommissioning programme is prioritised towards reducing and eliminating the greatest hazards first.

2.    The PFR waste is one of three different raffinates that arose historically from reprocessing nuclear fuel at Dounreay. Raffinate from materials test reactor fuel is now being solidified in a cementation plant at the site and this is also the reference strategy for raffinate from the Dounreay Fast Reactor fuel.

3.    High-level radioactive waste is generally distinguished from intermediate-level waste when it has thermal power greater than 2kW/m 3 and requires to be stored in a way that takes account of increases in temperature. The thermal power of the PFR raffinate has diminished to a maximum of 135W/m3 and cooling coils fitted to the storage tanks are no longer used. UKAEA believes the raffinate now meets the definition of intermediate-level waste.

4.    More information about Dounreay’s raffinates can be found in Public Participation Newsletter No. 4, which is being delivered today to more than 800 stakeholders. It can also be found at
      www.ukaea.org.uk/dounreay/dsrpnews.htm

5.    Decommissioning Dounreay is worth approximately £80 million a year to       the economy of the Highlands in general and Caithness and north Sutherland in particular through nett salaries, pensions, contracts and sub-contracts.  One in five jobs in Caithness and north Sutherland depend on decommissioning.  Across Scotland, it accounts for 2,930 jobs.