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Conference Article: Evaluation of graphite safety issues for the British production piles at Windscale: Graphite sampling in preparation for the dismantling of Pile 1 and the further safe storage of Pile 2

Marsden, B.J.; Preston, S.D.; Wickham, A.J. (AEA Technology plc, Warrington (United Kingdom)); Tyson, A. (Process and Radwaste Chemistry Dept., AEA TEchnology plc, Windscale (United Kingdom))

Abstract

The two air-cooled graphite-moderated production piles at the UK Sellafield site (formerly Windscale) have not operated since the late 1950s following the fire in Pile no. 1 in 1957. Although limited graphite trepanning took place immediately following the fire (mainly in the undamaged reactor, Pile no. 2), it has been deemed necessary to obtain new samples and extensive data to support the intended programme, which is for further 'Safe Storage' of Pile 2 and for the dismantling of Pile no. 1. The reactors (especially Pile no.2) contain significant Wigner energy, and elaborate precautions have been applied to ensure that intrusive operations cannot lead to energy releases. The paper discusses the visual surveys, trepanning procedure and the analytical data which have been obtained from the samples. There appear to be no obstacles to the continued storage of Pile no.2. For Pile no.1, the data will be used to support the safety case now being developed for dismantling and will define acceptable handling, storage and disposal procedures for the graphite blocks.

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key words: Gas Cooled Reactor, Nuclear Technology
Reference:
Technical committee meeting on technologies for gas cooled reactor decommissioning, fuel storage and waste disposal. Juelich (Germany) 8-10 Sep 1997
International Atomic Energy Agency, Vienna (Austria)
IAEA-TECDOC--1043, pp:213-223