The UKAEA Prototype Fast Reactor at Dounreay had a liquid sodium cooled core. Following its shut down in 1994, the liquid metal is being removed from the reactor and other vessels by means of specialised equipment and reacted with an aqueous solution of sodium hydroxide in a special vessel. The reaction products are neutralised with hydrochloric acid to produce a saline solution. The reactor sodium delivery and processing equipment is all of novel design. As sodium has been withdrawn from the vessel, it has been necessary to switch-off the primary sodium pumps (used to heat the sodium) and the reactor is now kept at temperature by a purpose designed electric heater and a NaK loop heater.

A primary sodium extract pump has currently removed about 500tonnes of primary sodium from the reactor. As the level falls, special equipment will be used to punch a hole in the primary circuit pipework and to drill the strongback to allow trapped sodium to drain for extraction. At the time of production of this paper, the 500tonnes of primary sodium, removed from the reactor vessel, had been successfully processed by the Sodium Disposal Plant, giving a total in excess of 980tonnes of sodium processed (>63% of the total PFR sodium inventory) including commissioning and proving operations.

This total sodiumIliquid metal processed figure is considerably in excess of the previous world record of 633tonnes, set by the EBR II sodium disposal facility in Idaho USA.