On January 27, 2019, at 1913
CST, with the University of Missouri-Columbia Research Reactor (
MURR) operating at 10
MW in the automatic control mode, the
Lead Senior Reactor Operator (LSRO) was conducting surveillance
Technical Specification (TS) 4.2.a, which states, 'All control blades, including the regulating blade, shall be verified
operable within a shift.' During this shiftily verification of control blade operability, all blades were initially verified
operable. However, when banking the control blades to their final position after all blades were satisfactorily tested a few seconds earlier,
shim control blade 'A' would not move in the inward direction. The LSRO then immediately shut down the reactor by initiating a
manual scram by placing the Master Control Switch 1S1 to the 'TEST' position. The LSRO completed all immediate and subsequent actions of reactor emergency procedure REP-2, 'Reactor
Scram,' and verified all
shim control blades were fully inserted.
The inability to manually insert shim control blade 'A' with Control Rod Operate Switch 1S4, which inserts and withdraws the control blade, is a deviation from TS 3.2.a, which states, 'All control blades, including the regulating blade, shall be operable during reactor operation.'
Troubleshooting revealed a problem with an electrical contact on
Control Rod Operate Switch 1S4, and it has since been replaced. The reactor has not returned to operation at the time of this email. However, permission from the Reactor Facility Director has been obtained to restart the reactor once scheduled maintenance activities have been completed. A detailed event report will follow within 14 days as required by
MURR TS 6.6.c(3).