Switch off of a protection device during periodic inspection

On the 2nd of October 1998, while the Phebus reactor was in shutdown, the protection system was completely switched off during a periodic inspection of control rods.
The reactor includes 6 control rods whose good operation is periodically tested. Each rod is successively moved during the test, while the five other ones are maintained in safe position. Instead of switching off the protection system for the only rod in testing the whole protection system was switched off so that it should have been possible to move one or more other control rods, in case of additional misoperation. In fact, a neutronic monitoring was still in function and the operator should have been able to order a scram in case of a rising signal.
During this incident, no consequence was registered, neither for the operator, nor for the environment.

Location: PHEBUS
Event date: Fri, 02-10-1998
Nuclear event report
Legenda & explanation