The Nuclear Regulatory Commission announced Friday it cleared the research reactor of the National Institute of Standards and Technology to restart following a Feb. 3, 2021, shutdown due to a higher than normal radiation level leaving the reactor building.
The Gaithersburg, Maryland, reactor shut automatically in response to the radiation escape, the NRC said in March 2021. The incident had no significant radiological consequences for workers, the public or the environment and all safety systems functioned properly to shut the reactor, the agency said.
Radiation doses were a small fraction of the regulatory limits for members of the public and radiation doses beyond the NIST property would have been even lower, the NRC said.
“We’ve reached this decision after extensive review of the event, NIST’s corrective actions and additional work the facility has done to ensure safe operation,” said Andrea Veil, director of the NRC’s Office of Nuclear Reactor Regulation. “We’re satisfied this research facility’s important systems and components are ready to go, and we’re satisfied the reactor staff are ready to carry out improved procedures for maintaining safety.”
The NRC will continue its increased oversight, she said.
“We are extremely pleased to have reached this milestone and to begin our return to normal operations,” said NIST Director Laurie Locascio.
Over the past two years, NIST said it has reviewed and updated training, operations, procedures, communications and attitudes toward safety. The test reactor operates at lower power, temperature and pressure than utility reactors that generate electricity.
One fuel element was not properly latched during a routine refueling outage in January 2021, the NRC said. The improperly latched fuel element became displaced or tilted, which blocked the coolant flow into the element and caused the element to overheat while the reactor power level was increased.
The corrective actions that NIST proposed include improvements to the latching procedures and enhancements to operator training.
In September 2021, NIST blamed the failure on inadequate training and qualification for operators, plant procedures, equipment and “inadequate management oversight.”
The training and qualification program was “not on par with programmatic needs,” it said in a report to the NRC. In addition, procedures as written do not “capture necessary steps” and procedural compliance was not enforced.
NIST cited a loss of experienced operators over the previous few years that resulted in “significantly fewer” experienced personnel.
The NIST Center for Neutron Research closed in 2020 due to COVID-19, resulting “in a lack of opportunity for training on refueling,” NIST said. And it blamed “some complacency” on staff who failed to place enough importance of latch checks, a part of the plant’s refueling procedures.
