The following was received via e-mail:
On July 1, 2019, sometime between 1100 and 1200 CDT with the reactor shut down and during performance of electrical preventative maintenance, the University of Missouri-Columbia Research Reactor (MURR) deviated from Technical Specification (TS) 3.4 because reactor containment integrity did not exist for approximately ten (10) minutes while the reactor was not secured, as defined by TS 1.26.
During this event time, two (2) shim control rod drive mechanisms were not installed because scheduled work was in progress on these drive mechanisms. Therefore, the reactor was not secured per TS definition 1.26, but the reactor was shut down per TS definition 1.27. Also during this time, and unknown to the Control Room operators, an Electronics Technician opened the two (2) electrical motor breakers to the reactor containment system's two (2) automatically-closing doors one at a time for approximately 5 minutes each.
Though this event happened on July 1, no NRC-licensed operator knew that the automatically-closing door motor breakers had been opened on July 1 until mid-day on July 3. Once the abnormal occurrence was realized, the Reactor Facility Director was briefed on the situation on the afternoon of July 3, and he gave permission to continue reactor operation in accordance with TS 6.6.c.(4).
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 as established in TS Section 3.0.
A detailed event report will follow within 14 days as required by
TS 6.6.c.(3).