Preliminary results of an ongoing internal analysis by the National Institute of Standards of Technology (NIST) indicate that inadequacies in training and procedures led to damage to a single fuel element in its research reactor, causing the Feb. 3, 2021, alert at the NIST Center for Neutron Research (NCNR). NIST has notified the Nuclear Regulatory Commission (NRC) and has already begun updating its policies and procedures to ensure these inadequacies are addressed.
The findings do not change the previously reported results of the event. The public was safe at all times, and radiation levels outside the confinement building remained well below regulatory health and safety limits. The NCNR is designed to keep the public safe even in a worst-case scenario.
“We take full responsibility for any failures that caused the alert on Feb. 3, 2021, and regret any concerns the alert caused the local community,” said James Olthoff, who is performing the non-exclusive functions and duties of the under secretary of commerce for standards and technology and NIST director. “We have already begun a thorough review of our procedures and training protocols to identify gaps. We are fully committed to correcting our procedures and protocols to ensure that this will never happen again.”
The preliminary evidence suggests that a single fuel element was not securely latched into place before the reactor was started on the morning of Feb. 3. The unlatched element apparently shifted, which may have prevented the proper flow of coolant water. This may have caused the excessive heating of the element, reported by NIST to the NRC on March 2.
At this point, NIST believes the latching error may have been the result of 1) inadequate training and proficiencies in fuel latching; 2) inadequate procedures in fuel movements and latching; 3) a lack of enforcement of procedural compliance; and 4) inadequate implementation of latch verification methods.
NIST has provided an initial verbal report of these findings to the NRC, and within 14 days will submit a written report. The NRC posts all such reports to its public website.
Although the internal analysis is still in progress, NIST intends to complete a corrective action plan to address the identified procedural and training inadequacies by Sept. 1. The NCNR Safety Evaluation Committee, which includes subject matter experts from external organizations and NIST, will review the root cause analysis and assess the response to the Feb. 3 event. Additionally, NIST plans to engage external, independent experts to assess the event, its cause and planned corrective actions.
NIST will submit a report on its internal analysis to the NRC, as well as a plan for all corrective actions, before seeking NRC approval to restart the reactor.