NRC Generic Letter 81-22, Engineering Evaluation of the H.B. Robinson Reactor Coolant System Leak on 1/29/81

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MAY 5, 1981

TO ALL LICENSEES OF OPERATING PLANTS AND HOLDERS OF CONSTRUCTION PERMITS

Gentlemen:

SUBJECT: ENGINEERING EVALUATION OF THE H. B. ROBINSON REACTOR COOLANT SYSTEM LEAK ON JANUARY 29, 1981 (GENERIC LETTER NO. 81-22)

Enclosed is our Engineering Evaluation Report for the Robinson Event. The primary reason for our evaluation was the loss of approximately 6,000 gallons of reactor coolant water from two separate leaks in the letdown train of the Chemical and Volume Control Letdown System (CVCS).

The evaluation is being forwarded for your information and training purposes. The evaluation of the event did not identify any safety concerns or any required immediate actions. There are four areas, however, which are under consideration for further action:

1. Whether a requirement should be placed upon operating plants to establish a procedure for identification and recovery from a spurious safety injection actuation (if such a procedure is not already taken place).

2. Whether criteria for terminating SI should include provisions for isolating charging since charging flow could be considered high pressure safety injection for very small breaks.

3. Whether there is a need for a direct reactor trip on a safety injection actuation at other Westinghouse plants which do not have a direct trip.

4. Whether operation of the isolation valves in the CVCS at Robinson is causing the system to be operated in a manner which is contrary to its design bases.

If you have any questions regarding this evaluation, please contact your Project Manager.

Sincerely,

Darrell G. Eisenhut, Director Division of Licensing Office of Nuclear Reactor Regulation

Enclosure: As stated