ML14170A553
| ML14170A553 | |
| Person / Time | |
|---|---|
| Site: | Harris, Brunswick, Robinson  |
| Issue date: | 11/16/1979 |
| From: | O'Reilly J NRC Office of Inspection & Enforcement (IE Region II) |
| To: | Jackie Jones Carolina Power & Light Co |
| References | |
| NUDOCS 7912110540 | |
| Download: ML14170A553 (6) | |
Text
0 UNITED STATES NUCLEAR REGULATORY COMMISSION REGION II 101 MARIETTA ST., N.W., SUITE 3100 ATLANTA, GEORGIA 30303 NOV 16 1979 In Reply Refer To:
RII:JPO 50-325, 50-324 50-400, 50-401 50-50-403 50-261 Carolina Power and Light Company ATTN: J. A. Jones Senior Executive Vice President and Chief Operating Officer 411 Fayetteville Street Raleigh, North Carolina 27602 Gentlemen:
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.
Sincerely, James P. O'Reilly Director
Enclosures:
- 1.
IE Information Notice No. 79-29
- 2.
List of IE Information Notices Issued in the Last Six Months Q--2 10 A)
NOV 16 7979 Carolina Power and Light Company
-2 cc w/encl:
A. C. Tollison, Jr.
Plant Manager Box 458 Southport, North Carolina 28461 R. Parsons, Site Manager Post Office Box 101 New Hill, North Carolina 27562 R. B. Starkey, Jr., Plant Manager Post Office Box 790 Hartsville, South Carolina 29550
SSINS No.: 6300 Accession No.:
7910250490 UNITED STATES NUJCLEAR REGULJATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C. 20555 November 16, 1979 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 (ICS) 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 ICS, 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 ICS and RCS conditions were restored.
Although 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.
IE Information Notice No. 79-29 Enclosure November 16, 1979 Page 1 of 2 LISTING OF IE INFORMATION NOTICES ISSUED IN THE LAST SIX MONTHS Information Subject Date Issued To Notice No.
Issued 79-29 Loss of Nonsafety-Related 11/16/79 All power reactor Reactor Coolant System facilities holding Instrumentation During Ols and CPs Operation 79-28 Overloading of Structural 11/16/79 All power reactor Elements Due to Pipe Sup-facilities holding port Loads OLs and CPs 79-27 Steam Generator Tube 11/16/79 All power reactor Ruptures at Two PWR facilities holding Plants OLs and CPs 79-26 Breach of Containment 11/5/79 All power reactor Integrity facilities holding OLs and CPs 79-25 Reactor Trips at Turkey 10/1/79 All power reactor Point Units 3 and 4 facilities holding OLs and CPs 79-24 Overpressurization of 10/1/79 All power reactor Containment of a PWR facilities holding Plant After a Main Steam OLs and CPs Line Break 79-23 Emergency Diesel Generator 9/26/79 All Holders of CPs Lube Oil Coolers and OLs 79-22 Qualification of Control 9/17/79 All Holders of CPs Systems 9/14/79 All Holders of OLs 79-21 Transportation and Commer-9/11/79 All Licensees as Supple cial Burial of Radioactive mental Information to Materials IE Bulletin Nos. 79-19
& 79-20 79-20 NRC Enforcement Policy 9/7/79 All Holders of Reactor (Rev. 1)
NRC Licensed Individuals OLs and CPs and Production Licensees with Licensed Operators 79-20 NRC Enforcement Policy 8/14/79 All Holders of Reactor NRC Licensed Individuals OLs and CPs and Production Licensees with Licensed Operators
IE Information Notice No. 79-29 Enclosure November 16, 1979 Page 2 of 2 LISTING OF INFORMATION NOTICES ISSUED IN THE LAST SIX MONTHS Information Subject Date Issued To Notice No.
Issued 79-19 Pipe Cracks in Stagnant 7/18/79 All Holders of Reactor (Correction -
Borated Water Systems at OLs and CPs Enclosure)
PWR Plants 79-19 Pipe Cracks In Stagnant 7/17/79 All Holders of Reactor Borated Water Systems At OLs and CPs PWR Plants 79-18 Skylab Reentry 7/6/79 All Holders of Reactor OLs 79-17 Source Holder Assembly Damage 6/20/79 All Holders of Reactor Damage From Misfit Between OLs and CPs Assembly and Reactor Upper Grid Plate 79-16 Nuclear Incident at Three 6/22/79 All Research Reactors Mile Island and Test Reactors with OLs 79-15 Deficient Procedures 6/7/79 All Holders of Reactor OLs and CPs 79-14 NRC Position of Electrical 6/11/79 All Power Reactor Cable Support Systems Facilities with a CP 79-12A Attempted Damage to New 11/9/79 All Fuel Facilities, Fuel Assemblies Research Reactors, and OLs and CPs