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Nuclear Event – Non-power Reactor Shutdown: USGS TRIGA Reactor | Denver Federal Center in Lakewood, Colorado.


Technological Hazard  – Nuclear Event

250 kW TRIGA Reactor

Similar 250 kW TRIGA Neutron Radiography . This Neutron 250 kW TRIGA reactor is equipped with two beam tubes and two separate radiography stations and used for neutron radiography irradiation of small test components. The blue glow is caused by Cherenkov radiation. The light water surrounding the core provides ample radiation protection for observers. Image Source: Wikimedia Commons

North America – USA | State of Colorado,  USGS TRIGA® reactor
Location: 39°43’10.7″N 105°07’15.8″W
Present Operational Age: ~47 years

Nuclear Event in USA on Thursday, 30 June, 2016 at 07:15 [MDT].


“At 0712 [MDT] on 6/30/16 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 0715 [MDT], as power was passing through [approximately] 200 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% when it should have been reading [approximately] 20%. The reactor was then shutdown, Reactor Supervisor notified, and troubleshooting commenced. Shortly after this, the NP1000 signal cable was found to have the coaxial cable pulled out of one of the connectors in the signal path. Repair, troubleshooting, and testing were performed to resolve the problem. At 0804 [MDT] the reactor was started up and 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% power, but the cable problem would have prevented the high power scram from occurring in that instrument.”

The licensee will notify the NRC Project Manager.

Source: NRC  Event Number: 52054

See Also

List of Non-Power Reactors in America

Non-Power Reactors in America

Non-Power Reactors in America. Source:

These small reactors are located at educational institutions and other organizations and used for research or training. Research reactors produce radioisotopes for nuclear medicine, are used to train people in the nuclear sciences, and are used as a laboratory tool, as a producer of byproduct material, or as a source of radiation for experiments.

TRIGA® Nuclear Reactors

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