The contaminated alloy of sodium and potassium was used as coolant in the defunct reactor and its safe destruction is one of the Nuclear Decommissioning Authority’s biggest priorities in the UK today.
Its destruction continued around the clock during the holidays, taking the total destroyed to date to more than 161,000 litres.
The site is on course to complete the destruction of the estimated 6300 litres still remaining by the end of March.
The toxic metal is lifted in batches from inside the reactor and its six miles of cooling pipes. The NaK alloy is processed through a purpose-built chemical plant to neutralise the alkalinity and extract the caesium contamination, leaving a salty water that can be discharged safely to sea.
Its rate of destruction means the major radiological and chemical hazard inside the reactor is reducing at a rate of 20 million bequerels a second.
“We’re on course to destroy the remaining six tonnes by the end of March and deliver a major clean-up milestone for the Nuclear Decommissioning Authority,” said Andy Swan, the engineer in charge of the reactor decommissioning programme at site closure contractor DSRL.
Once the bulk of the metal is destroyed, attention will turn to flushing out and destroying the final eight tonnes of residue from the system.