Consequential failure of Fuelling Machine Interlock at Buffer Storage Tube

After removal of a new fuel assembly from a buffer store tube, the fuelling machine inserted the short shield plug and was then jacked up. Upon trying to move away fom the standpipe, the machine showed signs of stalling and a bang was heard. Refuelling was immediately suspended and the investigations have since shown that the grab had not disengaged from the short shield plug due to failure of a drive coupling on the grab disengage drive. At the time when the machine had tried to move away, part of the short shield plug became separated and dropped into the buffer store tube.

Location: HEYSHAM-1 UNIT A
Event date: Mon, 11-03-2002
Nuclear event report
Legenda & explanation