At 0914 MDT on 7/1/16, a routine GSTR [Geological Survey
TRIGA Reactor] startup and ascent to 900 kW was initiated after successful completion of the daily prestart checks and an excess reactivity check. At 0919 as power was passing through approximately 50 kW, it was clear to the operator that one of the three power instruments (the NP1000) was not functioning since it was still reading 0 percent when it should have been reading >5 percent. The reactor was scrammed, Reactor Supervisor notified, and troubleshooting commenced. Shortly after this, the NP1000 signal cable was found to have an intermittent connection through a tee connector that was installed at the instrument box. The connector was replaced to resolve the problem and tested satisfactorily. At 1050 the reactor was started up again. All power instrumentation operated correctly and the daily power operation was performed without further problems.
The NP1000 is a required safety instrument for operation of the reactor, so malfunction of the instrument is a violation of the facility's Technical Specifications.
Specifically, Specification E.7 states: 'The type and minimum number of safety systems which shall be operable for reactor operation are shown in Table I.' Table I requires the NP1000 to provide a high power scram at 110 percent power, but the connector problem would have prevented a high power scram from occurring in that instrument.
The licensee notified the NRC Project Manager and the NRC
SME (Subject Matter Expert) for Research and Test Reactors.