ML19262A993
| ML19262A993 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 11/19/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Lundvall A BALTIMORE GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7912110394 | |
| Download: ML19262A993 (1) | |
Text
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[pt **c UNITED STATES S [3 e(f')o NUCLEAR REGULATORY COMMISSION
""*d/ ' [E REGION I 3J~
631 PARK AVENUE 0,
,o' KING OF PRUSSIA, PENNSYLVANIA 19406
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Docket Nos. 50-317 NDV 19 m3 50-318 Baltimore Gas and Electric Company ATTN:
Mr. A. E. Lundvall, Jr.
Vi e President, Supply P. O. Box 1475 Baltimore, Maryland 21203 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 pos-sible applicability 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 NRR 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 this office.
Sincerely,
/ s e fa h.
Boyce H. Grier Director
Enclosures:
1.
IE Information Notice No. 79-29 2.
List of Recently Issued Information Notices CONTACT:
W. H. Baunack (215-337-5253) cc w/encis:
R. M. Douglass, Manager, Quality Assurance L. B. Russell, Chief Engineer W. Gibson, General Supervisor, Operational QA R. C. L. Olson, Senior Engineer K. H. Sebra, Principal Engineer 1530 303 7912110
ENCLOSURE 1 SSINS No.: 6300 Accession No.:
7910250490- [
UNITED STATES g
NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT m.
D] qQmK WASHINGTON, D. C.
20555 oo L5. Jlnl b
IE Information Notice No. 79-29 Date:
November 19, 1979 Page 1 of 2 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 techni-cian 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, >;ntil an operator could reach the equipment room and switch the inverter.nanually to the regu-lated 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 opera-tor, expecting this condition, started all makeup pumps and opened the asso-ciated 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 genera-tors 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 instru-ments onto diverse electrical supplies or to provide redundant instrumentation display channels for operator use from essential power supplies are also under 1530 304
IE Information Notice No. 79-29 Date:
November 19, 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 shich will recommend or request specific applicant or licensee actions.
This Information Notice is provided to inform licensees of a possibly signifi-cant 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.
1530 305
ENCLOSURE 2 IE Infonnation Notice No. 79-29 Date:
November 19, 1979 Page 1 of 1 RECENTLY ISSUED IE INFORMATION NOTICES Information Subject Date Issued to Notice No.
Issued 79-20 Same Title as 79-20 9/7/79 Same as 79-20 (Revision No. 1) 79-21 Transportation and Com-9/7/79 All Power and Research mercial Burial of Radio-Reactors with OLs active Material 79-22 Qualification of Control 9/14/79 All Power Reactor Faci-Systems lities with an OL or CP 79-23 Emergency Diesel Generator 9/26/79 All Power Reactor Faci-Lube Oil Coolers lities with an OL or CP 79-24 Overpressurization of Con-10/1/79 All Power Reactor Faci-tainment of a PWR Plant lities with an OL or CP After a Main Steam Line Break 79-25 Reactor Trips at Turkey 10/1/79 All Power Reactor Faci-Point Unit 3 and 4 lities with an OL or CP 79-26 Breach of Containment 11/5/79 All Power Reactor Facil-Integrity ities with an OL or CP 79-12A Attempted Damage to New 11/9f79 All Fuel Facilities, Fuel Assemblies Research Reactors and Power Reactors with an OL or CP 79-27 Steam Generator Tube 11/16/79 All Power Reactor Faci-Ruptures at Two PWR lities with an OL or CP Facilities 79-28 Overloading of Structural 11/16/79 All Power Reactor Faci-Elements Due to Pipe Support lities with an OL or CP Loads 1530 30l!