ML20033A888
| ML20033A888 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay, Palo Verde |
| Issue date: | 10/08/1981 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| Shared Package | |
| ML20033A887 | List: |
| References | |
| NUDOCS 8111300095 | |
| Download: ML20033A888 (1) | |
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October 8,1981 Docket Nos. 50-528, 50-529, 50-530 Arizona Public Service Company P. O. Box 21666 Phoenix, Arizona 85036 Attention: Mr. E. E. Van Brunt, Jr.
Vice President, fluclear Projects Gentlemen:
The enclosed infomation notice provides early notification of an event that may have significance. Accordingly, you should review the information notice for possible applicability to your facility.
No specific action or response is requested at this time; however, contingent upon the results of further staff evaluation, a bulletin or circular recom-mending or requesting specific licensee actions may be issued.
If you have questions regarding this matter, please contact this office.
Sincerely, enginsi signed tY R. H. Engelke R. H. Engelken Director
Enclosures:
1.
IE Infomation Notice No. 81-31 2.
List of Recently Issued IE Information Notices cc w/ enclosures:
F. W. Hartley, APS G. C. Andognini, Vice President, Electric Operations r
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SSINS No.: 6835 Accession No.:
8107230032 s
IN 81-31 UNITED STATES 2
NUCLEAR REGULATORY COMMISSION 4
OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON,.D.C. 20555 October 8, 1981 INFORMATION HOTICE NO. 81-31:
FAILURE OF SAFETY INJECTION VALVES TO OPERATE AGAINST DIFFERENTIAL PRESSURE Description of Circumstances:
Both trains of the San Onofre Unit I safety injection system were found to be inoperable when challenged under actual operating conditions on September 3, 1981. Following manual reactor trip from 88% power due to steam generator flow and level oscillations caused by a regulated power supply failure, low primary system pressure caused a safety injection initiation signal. The licensee reported that operators disnatched to the auxiliary building following the safety injection initiation signal found that neither of the safety injection valves, located in the discharge of both trains of the safety injection pumps, had opened as required. There were no adverse consequences in this particular event since there was no loss of coolant. accident..The reactor pressure remained above the safety injection pump's shutoff head and therefore no actual injection of water would have occurred if the valves had opened.
However, had reactor pressure decreased and actual injection been required, injection flow would not have been automatically available as designed.
The valves which failed to open are 14-inch Anchor Darling, Series 600, stain-less steel, Part No. SI-50-WDD valves using Greer Hydraulics No.- 832210 actuators.
Tests were conducted on these valves in the as-found condition following this event and both valves failed to open against the 1,200 psi differential pressure which would normally exist across the valves following a safety injection signal.
Pressure was lowered until one valve opened with a 520 psid and the other at 80 psid. Subsequent tests were performed after readjusting the valve packing to determine the cause of the failure. These tests also failed to provide con-sistent opening against a 1,200 psid. System modifications and further testing is under way to provide the necessary reliability for the safety injection system.
These valves had been regularly tested at each refueling outage, but the tests were not required to be performed with differential pressure across these valves.
Tnere may be systems and components at other facilities that are not periodical-ly tested under the differential pressure conditions at which they are designed to operate.
Consequently, we suggest that recipients of this. notice take appro-priate steps to determir.e whether or not situations similar to the above could exist at the recipients' plant (s).
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IN 81-31 October 8, 1981 Page 2 of 2 4
This information notice.is provided as 'an;early notification of a significant ~
safety matter that is still under review by the NRC staff.
If it is determined that actions.are required, such as additional periodic tests with differential pressure or other. actions,' you will = be. notified in an appropriateLmanner.
In the meantime, no response. to this notice-is required.
If you have questions regarding this matter, please contact.the: Director of the' appropriate Regional Office.~
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Attachment:
s Recently~ issued Information Notices 4
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Attachment IN 81-31 October 8, 1981 RECENTLY ISSUED IE INFORMATION NOTICES Information Date of Notice No.
Subject Issue Issued to 81-30 Velan Swing Check Valves 9/28/81 All power reactor facilities with an OL or CP 81-29 Equipment Qualification 9/23/81 All power reactor Testing Experience facilities with an OL or CP 81-28 Failure of Rockwell-Edward 9/3/81 All power reactor Main Steam Isolation Valves facilities with an OL or CP 81-27 Flammable Gas Mixtures 9/3/81 All power reactor in the Waste Gas Decay facilities with an Tanks in PWR Plants OL or CP 81-26 Compilation of Health 9/3/81 All power reactor Physics Related Information facilities with an Items OL or CP 81-25 Open Equalizing Valve 8/21/81 All power reactor of Differential Pressure facilities with an Transmitter Causes Reactor OL or CP Scram and Loss of Redundant Safety Signals 81-24 Auxiliary Feed Pump 8/5/81 All power reactor Turbine Bearing Failures facilities with an OL or CP 81-23 Fuel Assembly Damaged 8/4/81 All power reactor due to Improper Positioning facilities with er of Handling Equipment OL or CP 81-22 Section 235 and 236 7/31/81 All power rest Amendments to the reactor, fuel Atomic Energy Act fabrication and of 1954 reprocessing, and spent fuel storage licensees and applicants OL = Operating License CP = Construction Permit