NRC Generic Letter 1979-24
| ML031320296 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley, Millstone, Calvert Cliffs, Davis Besse, Salem, Oconee, Palisades, Kewaunee, Saint Lucie, Point Beach, Arkansas Nuclear, Prairie Island, Turkey Point, Crystal River, Haddam Neck, Ginna, Farley, San Onofre, Cook, Yankee Rowe, Maine Yankee, Rancho Seco, Zion, Fort Calhoun, Trojan, Crane |
| Issue date: | 06/26/1979 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| NUDOCS 7909140043, GL-79-024 | |
| Download: ML031320296 (2) | |
4t, KREQ9^ UNITED STATES -3 NUCLEAR REGULATORY COMMISSION
As an WASHINGTON. D. C
June 26, 1979 .304
-. L-Th-29X
ALL PRESSURIZER WATER REACTORS
Gentlemen:
reactor scram and Recently, because of operator error, an inadvertent tests of the safety injection occurred during monthly surveillance safeguards system at a PWR facility.
system had been At the time of the event, train "A" of the safeguards to inserting a high placed in "test", and the operator, in addition incorrectly in- steam flow signal required by the test, inadvertently resulted in a low steam serted a low steam pressure signal. This action in train "A" which pressure signal (signifying a main steam line break) and a reactor initiated main steam isolation valve (MSIV) Isolation scram. One MSIV, however, did not close because of a valve solenoid differential pressure between two steam lines failure. The resultant In the ensuing initiated a safety injection signal from train "B". feedwater regulation events several more equipment failures occurred. One The steam valve failed to close because of another solenoid failure. and one of the driven auxiliary feedwater pump tripped on overspeed fully reseat upon steam generator atmospheric relief valves failed to closure.
is of concern This occurrence, with its ensuing sequence of events, are raised serious questions that to the NRC staff because of the a very real problem due to the multiple equipment failures and whether the potential for could exist that has not been analyzed. For example, independent solenoid common mode failures (in this case two apparentlythat a problem does valve failures) should be investigated to ensure your previous not exist which could negate the criteria assumed in in system could lead to an overall reduction accident analyses or which reliability.
sense of This occurrence is also of concern because of an apparent in general and complacency towards periodic surveillance requirementshas all too often on engineered safeguards systems in particular which injection system resulted in inadvertent reactor scrams and safety challenges to the reactor actuations. From the standpoint of unnecessary of unnecessary thermal trip and the safeguards systems and the imposition this is stress cycles on reactor coolant system and its components, undesirable.
790 Doe' 4/4y
- 2 - June 26, 1979 events described in You and your plant supervisors should review the have occurred or could this letter, to determine whether similar errors exists for a problem occur at your facility and whether the potential previously considered.
associated with occurrences that you have not policies and procedures In addition, it is requested that management necessary to assure that multiple equip- be reviewed and strengthened as vigorously pursued and ment failures in safety-related systems will be previously considered analyzed to identify potential failure modes not ability of safety that could lead to a significant reduction in the requested to review are systems to function as required. Finally, you to determine whether your engineered safety system surveillance procedures that plant operators appropriate cautions are included and to ensure avoiding challenges to and supervisors are aware of the importance of the protective features of your facility.
submit, in accordance Within 30 days of receipt of this letter, please the results of with 10 CFR §50.54(f) of the Commission's regulations, reviews of these matters, we these reviews. In addition to licensing and Enforcement perform have requested that the NRC's Office of Inspection near future.
a followup inspection on these matters in the incerely, re . Eisenhut, Acting Director Division of Operating Reactors Office of Nuclear Reactor Regulation