ML18136A279
| ML18136A279 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 11/16/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Proffitt W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| NUDOCS 7912110587 | |
| Download: ML18136A279 (6) | |
Text
e UNITED STATES NUCLEAR REGULATORY COMMISSION REGION II 101 MARIETTA ST., N.W., SUITE 3100 ATLANTA, GEORGIA 30303 In Reply Refer To:
RII :JPO 50-338, 50-339
~
NOV 16 1979 Virginia Electric and Power Company Attn:
W. L. Proffitt Senior Vice President, Power P. O. Box 26666 Richmond, Virginia Gentlemen:
23261 This Information Notice is provided as an early notification of a possibly significant matter. It is expected that recipients will distribute this Notice to their operating personnel and will review the information for possible appli-cability to their facilities.
No specific action or response is requested at this time.
However, we anticipate that further NRC evaluations will result in issuance of an IE Circular, Bulletin or NRC Generic Letter in the near future which will recommend or request specific applicant or licensee actions.
If you have questions regarding the matter, please contact the Director of the appro-priate NRC Regional Office.
Enclosures:
- 1.
IE Information Notice No. 79-29 Sincerely,
- 2.
List of IE Information Notices Issued in the Last Six Months o.otf 0
I> 1'912I 5g7
Virginia Electric and Power Company cc w/encl:
W.R. Cartwright, Station Manager Post Office Box 402 Mineral, Virginia 23117 P. G. Perry Senior Resident Engineer Post Office Box 38 Mineral, Virginia 23117 W. L. Stewart, Manager Post Office Box 315
.Surry, Virginia 23883 NOV 16 1979
- r.
-l e
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT.
WASHINGTON, D. C.
20555 November 16, 1979 SSINS No.: 6300 Accession No.:
7910250~0 (/
~
IE Information Notice No. 79-29 LOSS OF NONSAFETY-RELATED REACTOR COOLANT SYSTEM INSTRUMENTATION DURING OPERATION This notice contains information regarding a loss of reactor coolant system instrumentation as a consequence of a failure of a static transfer switch to transfer to an alternate supply.
At 3:15 p.m. on November 10 with Unit 3 of the Oconee Station at 100 percent power, the main condensate pumps tripped, apparently as a result of a technician performing maintenance on the hotwell level control system.
This led to reduced feedwater flow to the steam generators, which resulted in a high reactor coolant system (RCS) pressure reactor trip and simultaneous turbine trip at 3:16:57 p.m.
At 3:17:15 p.m., the inverter power supply, nonsafety-related, feeding all power to the integrated control system (!CS) tripped and failed to automatically transfer its loads from the DC power source to the regulated AC power source.
The inverter had tripped due to blown fuses, resulting in loss of RCS indicators and recorders in the control room, except one wide range RCS pressure recorder.
This condition existed for approximately three minutes, until an operator could reach the equipment room and switch the inverter manually to the regulated AC source.
As a result of the power failure to the !CS, all valves controlled by the system assumed their respective fail positions.
This resulted in a cool down of the RCS to 1635 psi and 530 degrees F.
The operator, expecting this condition, started all makeup pumps and opened the associated high pressure injection valves to the RCS which limited the rate of RCS pressure reduction and associated reduction in pressurizer level.
At 3:20:42 p.m.,
power was restored to the !CS and RCS conditions were restored.
Alt~ough RCS cooldown limits were exceeded, the pressurizer and steam generators did not go dry, and at least 79 degrees F subcooling was maintained during this event.
No engineered safety features actuation setpoints were reached, and, except for the components discussed above, no component malfunc-tions occurred.
The licensee has installed a redundant electromechanical transfer switch between the loads and the regulated supply.
This switch will actuate and power the loads from the regulated supply should the original static switch fail to transfer.
Longer term resolution of the need or desirability to separate these instruments onto diverse electrical supplies or to provide redundant instrumentation display channels for operator use from essential power supplies are also under
IE Information Notice No. 79-29 November 16, 1979 Page 2 of 2 consideration. It is anticipated that further NRC evaluations will result in issuance of an IE Circular, Bulletin, or NRR Generic letter in the near future which will recommend or request specific applicant or licensee actions.
This Information Notice is provided to inform licensees of a possibly significant matter. It is expected that recipients will disseminate the information to all operational personnel working at their licensed facilities.,
If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
No written response to this Information Notice is required.
e IE Information Notice No. 79-29 November 16, 1979 LISTING OF IE INFORMATION NOTICES ISSUED IN THE LAST SIX MONTHS Information Notice No. 79-29 "79-28 79-27 79-26 79-25 79-24 79-23 79-22 79-21 79-20 (Rev. 1) 79-20 Subject Loss of Nonsafety-Related Reactor Coolant System Instrumentation During Operation Overloading of Structural Elements Due to Pipe Sup-port Loads Steam Generator Tube Ruptures at Two PWR Plants Breach of Containment Integrity Reactor Trips at Turkey Point Units 3 and 4 Overpressurization of Containment of a PWR Plant After a Main Steam Line Break Emergency Diesel Generator Lube Oil Coolers Qualification of Control Systems Transportation and Commer-cial Burial of Radioactive Materials NRC Enforcement Policy NRC Licensed Individuals NRC Enforcement Policy NRC Licensed Individuals Date Issued 11/16/79 11/16/79 11/16/79 11/5/79 10/1/79 10/1/79 9/26/79 9/17/79 9/14/79 9/11/79 9/7 /79 8/14/79 Enclosure Page 1 of 2 Issued To All power reactor facilities holding Ols and CPs All power reactor facilities holding OLs and CPs All power reactor facilities holding OLs and CPs All power reactor facilities holding OLs and CPs All power reactor facilities holding OLs and CPs All power reactor facilities holding OLs and CPs All Holders of CPs and OLs All Holders of CPs All Holders of OLs All Licensees as Supple-mental Information to IE *Bulletin Nos. 79-19
& 79-20 All Holders of Reactor OLs and CPs and Production Licensees with Licensed Operators All Holders of Reactor OLs and CPs and Production Licensees with Licensed Operators
IE Information Notice No. 79-29 November 16, 1979 Information Notice No. 79-19 (Correction -
Enclosure) 79-19 79-18 79-17 79-16 79-15 79-14 79-12A LISTING OF INFORMATION NOTICES ISSUED IN THE LAST SIX MONTHS Subject Date Issued Pipe Cracks in Stagnant 7/18/79 Borated Water Systems at PWR Plants Pipe Cracks In Stagnant 7/17/79 Borated Water Systems At PWR Plants Skylab Reentry 7/6/79 Source Holder Assembly Damage 6/20/79 Damage From Misfit Between Assembly and Reactor Upper Grid Plate Nuclear Incident at Three Mile Island Deficient Procedures NRC Position of Electrical Cable Support Systems Attempted Damage to New Fuel Assemblies 6/22/79 6/7 /79 6/11/79 11/9/79 Enclosure Page 2 of 2 Issued To All Holders of Reactcor OLs and CPs All Holders of Reactor OLs and CPs All Holders of Reactor OLs All Holders of Reactor OLs and CPs All Research Reactors and Test Reactors with OLs All Holders of Reactor OLs and CPs All Power Reactor Facilities with a CP All Fuel Facilities, Research Reactors, and OLs and CPs