Investigations into the February fuel failure and resultant alert at a test reactor in the US identified seven root causes, including inadequate operator training and incomplete written procedures, according to documents submitted by the NIST to the Nuclear Regulatory Commission.

The reactor operator, the US National Institute of Standards and Technology Center for Neutron Research in Gaithersburg, Maryland, said it will take 18 corrective actions to prevent a recurrence and is seeking NRC permission to restart the 20 MW(t) unit, used to produce cold and thermal neutrons for scientific research.