Resolution of Generic Safety Issues: Issue 9: Reevaluation of Reactor Coolant Pump Trip Criteria ( NUREG-0933, Main Report with Supplements 1–34 )
Under the scope of the TMI Action Plan Item II.K.3 in NUREG-0660,48 the NRC Bulletin and Orders Task Force conducted generic reviews of the loss-of-feedwater and small-break loss-of-coolant events on all operating reactors. These reviews consisted of an evaluation of systems reliability analyses, guidelines for emergency procedures, and operator training related to these events.
As a result of these reviews, a number of recommendations for improvements were made and documented in NUREG-0611,93 NUREG-0626,94 NUREG-0635,95 NUREG-0565,96 and NUREG-0623.97 Included among these recommendations was the reevaluation of reactor coolant pump trip criteria.
The issue of reevaluation of reactor coolant pump trip criteria involves the potential improvement that might be achieved by establishing better criteria on when to allow the operation of reactor coolant pumps and when to trip them. It was believed that better criteria might allow the use of reactor coolant pumps to aid in recovery from certain transients while still ensuring that these pumps could be tripped during a small-break LOCA. This issue was given consideration as a candidate USI in NUREG-070544 but was not recommended for designation as a USI because the safety evaluations of transients used for licensing acceptability do not assume the availability of the reactor coolant pumps.