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Highly active storage tank emptied two years early
Emptying of one of Sellafield’s Highly Active Storage Tanks (HAST) two years ahead of schedule has been successfully achieved. The transfer of the last 59 cubic metres of liquor from HAST 4, equivalent to 1,500te of historic Magnox reprocessing, took place in two stages during January and May, and required careful coordination of a number of safety factors, both conventional and radiological, and operational constraints.
Completing the transfer of HAST 4 builds on the previous transfer of liquor from HAST 3 which sits within the same cell. This means the team can now carry out radiation surveys in preparation for the Post Operational Clean Out of the cell, and its ultimate decommissioning.
Highly Active Storage Tanks (HAST) 1 – 8 were last used in the 1970s, to take liquors from early Magnox reprocessing operations. Since then, a careful monitoring programme has ensured that they remain in a safe state, prior to transfer into the new side storage tanks and onward vitrification.
Sarah Porter, moves coordinator for the project, outlined the challenges that were faced: “Because of the nature of what was being transferred, the work had to be carried out on a continuous basis. The first stage involves 815 small lifts and the second stage, 426.
“All of these had to be individually monitored to ensure that workers dose limits were strictly controlled. The key to success was the flexibility and teamwork shown by the teams. Bringing forward the transfer of this material underlines the innovative approach needed to move the company forward to ensure success in delivering for the Nuclear Decommissioning Authority.”
