On May 30, 2018, at 07:10
CST, with the reactor operating at 10
MW in the automatic control mode,
MURR [University of
Missouri Research Reactor] was shut down due to a failure of the
Control Rod Operate Switch 1S4 to move the
shim control blades in the inward direction. The Reactor Safety (
Scram) and Rod-Run-In Systems were unaffected by this failure and remained operational and would automatically and manually initiate, if required. This email is a required notification per
MURR TS [Technical Specification] 6.6.c(1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by
MURR TS 1.1.b, has occurred.
MURR was not in compliance with all of the Limiting Conditions for Operations (LCOs) as established in Section 3.0. Specifically,
MURR was not in compliance with
TS 3.2.a, which states, All control blades, including the regulating blade, shall be
operable during reactor operation.
Control Rod Operate Switch 1S4 was replaced and retest was conducted satisfactorily, which included verifying inward and outward movement of all 4
shim control blades. Authorization was received from the Reactor Facility Director, as required by
TS 6.6.c(4), to
restart the reactor and resume 10
MW operation. A detailed event report will follow within 14 days as required by
MURR TS 6.6.c(3).
The failure was identified during scheduled testing and the reactor was shutdown by manual Scram in accordance with procedures.
The licensee notified the NRC Research and Test Reactor Project Manager (Wertz).