|CONTROL BLADE INOPERABLE
"On April 28, 2019, at 0633 CDT, 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 verification of control blade operability, shim control blades 'A,' 'B,' 'C,' and the regulating blade were verified operable. However, shim control blade 'D' would not move in the inward direction. The LSRO then immediately shut down the reactor by initiating a manual scram by placing Master Control Switch 1S1 to the 'TEST' position. The LSRO completed all immediate and applicable subsequent actions of reactor emergency procedure REP-8, 'Control Rod Drive Mechanism Failure or Stuck Rod,' and verified all shim control blades were fully inserted.
"This email is a required notification per TS 6.6.c(1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by TS 1.1.b, has occurred. MURR was not in compliance with all of the Limiting Conditions for Operations (LCOs) as established in TS Section 3.0. The failure of the control rod drive mechanism to insert shim control blade 'D' is a deviation from TS 3.2.a, which states, 'All control blades, including the regulating blade, shall be operable during reactor operation.' In addition, shim control blade 'D' would not have inserted during the activation of any rod run-in function listed in TS 3.2.f - shim control blades 'A,' 'B,' and 'C' would have inserted. All reactor safety system scram functions were unaffected and remained operable during this event.
"Troubleshooting revealed a broken wire to the inward motor winding of shim blade 'D' control rod drive mechanism. The wire was repaired, and the shim control blade 'D's operability was tested satisfactorily. Permission from the Reactor Facility Director was obtained prior to reactor startup per TS 6.6.c(4), and the reactor returned to 10 MW operation at 1319 CDT on April 28. A detailed event report will follow within 14 days as required by TS 6.6.c(3)."