The Nuclear Installations Inspectorate (NII) has launched a nationwide check on tankers delivering coolant gas after a scare that a tanker going to Scottish Nuclear’s Hunterston B plant could have been contaminated with radioactivity.
The NII wrote to the four nuclear operators that take such deliveries of CO2 coolant gas and asked them to demonstrate `as a matter of urgency’ that they have systems to check tankers leaving their sites are clean.
The possible contamination of the tanker at Hunterston led to fears that radioactivity could be passed on to other customers of the transport company, Messer UK – fears heightened by the subsequent discovery of radioactive traces in a CO2 cylinder at the Carlsberg-Tetley brewery in Alloa.
An NII spokesman said there had been a `real possibility’ that the tanker could have been contaminated.
The NII is today delivering its report on the incident to Scottish secretary Michael Forsyth, who is expected to make a statement.
The risk to the public arose from apparent failures of equipment and/or procedures in the supposedly one- way system for introducing fresh coolant gas into the reactors at Hunterston.
Road tankers discharge the gas into a holding tank, from where it is fed into the cooling circuits of the reactors. Non-return valves should prevent any back-flow from the cooling circuit to the tank. Once radioactivity is in the tank, however, the NII spokesman said there was `a clear pathway’ for it to find its way into a road tanker during the discharge operation.
Dr Robin Jeffrey, Scottish Nuclear’s chief executive suggested that valve failure may have been responsible.