ML18153B850
| ML18153B850 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 08/03/1989 |
| From: | Varga S Office of Nuclear Reactor Regulation |
| To: | Lough T VIRGINIA, COMMONWEALTH OF |
| References | |
| NUDOCS 8908110336 | |
| Download: ML18153B850 (5) | |
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e Docket No. 50-280 Mr. W. Timothy Lough Special Projects Engineer State Corporation Commission Division of Energy Regulation P. 0. Box 1197 Richmond, Virginia 23209
Dear Mr. Lough:
August 3, 1989
SUBJECT:
SURRY, UNIT 1 - SEPTEMBER 14, 1988 OUTAGE By letter dated July 5, 1989 to Mr. Bart Buckley of the NRC staff, you stated that you were investigating the September 14, 1988 Surry, Unit 1 outage and requested responses to certain questions related to that outage.
Our responses to these questions are enclosed.
The NRC believes that the Virginia Electric and Power Company acted responsibly in shutting down Surry, Unit 1 upon becoming aware of a concern about the load-sequencing capability of the emergency diesel generators.
The load-sequencing of the emergency diesel generators, an important safety consideration in accident mitigation, was subsequently found to be inadequate for certain accident scenarios. This necessitated* modification and testing of the diesel generators.
Sincerely, Original signed by Walter R. Butler FOR Steven A. Varga, Director Division of Reactor Projects I/II Office of Nuclear Reactor Regulation
Enclosure:
Responses to Questions w/attachments cc w/enclosure:
See next page DISTRIBUIION
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Hunton and Williams Post Office Box 1535 Richmond, Virginia 23212 Mr. Michael Kansler, Manager Surry Power Station Post Office Box 315 Surry, Virginia 23883 Resident Inspector Surry Power Station U.S. Nucl~ar Regulatory Commission Post Office Box 166, Route 1 Surry, Virginia 23883 Mr. Sherlock Holmes, Chairman Board of Supervisors of Surry County Surry County Courthouse Surry, Virginia 23683 Mr. W. R. Cartwright Vice President - Nuclear Virginia Electric and Power Company 5000 Dominion Blvd.
Glen Allen, Virginia 23060 Regional Administrator, Region II U.S. Nuclear Regulatory Conmission 101 Marietta Street N.W., Suite 2900 Atlanta, Georgia 30323 C. M. G. Buttery, M.D., M.P.H.
Departm~nt of Health 109 Governor Street Richmond, Virginia 23219 Attorney General Supreme Court Building 101 North 8th Street Richmond, Virginia 23219 Mr. W.R. Cartwright Vice President - Nuclear Virginia Electric and Power Company 5000 Dominion Blvd.
Glen Allen, Virginia 23060
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Question 1 ENCLOSURE RESPONSES TO ~UESTIONS RELATING TO SEPTEMBER 14, 1988 SURRY, UNIT 1 OUTAGE On August 22, 1985, when a LCO was declared at the Duane Arnold Energy Center, the licensee did not shut down the plant.
They took temporary corrective actions. Permanent corrective actions were taken later during a scheduled refueling outage.
Should/could Virginia Power have done the same?
Answer 1 On November 4, 1984, there was an explosion and fire in the auxiliary transformer which normally supplies power to the non-vital loads at the Duane Arnold Energy Center.
With the auxiliary transformer out of service, the non-vital loads were being powered by the startup transformer.
The plant vital loads, which ordinarily would be supplied by the startup transformer, were being powered by the standby transformer.
The startup transformer was capable of supplying both vital and non-vital loads but would have resulted in higher transformer temperature and lower voltages.
Subsequently, on August 22, 1985, it was discovered that with the above electrical bus configuration, the loss of the standby transformer coincident with a loss-of-coolant accident (LOCA) signal would result in the four residual heat removal pumps and two core spray pumps simultaneously loading on their respective diesel generators instead of sequencing.
As a result of this concern, the licensee entered a 24-hour limiting conditions for operation (LCO), declaring both diesel generators inoperable. The licensee's design permitted them to take temporary corrective action within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> by placing four test switches in the test position, which would result in the proper sequencing of loads.
A temporary fix, such as that which was implemented at Duane Arnold, was not feasible at Surry.* The Virginia Electric and Power Company (VEPCO) performed extensive analyses, including a re-evaluation of various accidents.
As a result of these analyses, it was necessary to make modifications to the sequencing pattern which required special testing of the emergency diesel generators to assure they were capable of handling the required loads during a LOCA followed by a loss of power 5 to 60 minutes later.
These analyses and corrective actions could not have been completed within the LCO, which requires that the plant be placed in at least hot shutdown within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and at least cold shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
Similar modifications were made at Surry, Unit 2 which had already shut down for a refueling outage.
Question 2 According to Kenneth Clark, NRC Spokesman in Atlanta (Richmond Times-Dispatch, Septenber 17, 1988), the NRC asked Virginia Po~er (after inspec-tion in May 1988) to study EOG design at Surry.
Does this refer to the IE Notice 85-91, or does it mean that the NRC indeed directed the Company to stuqy EOG design at Surry?
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. ; Answer 2 During an NRC inspection in May 1988, certain concerns about the diesel generators were raised by NRC.
However, thes~ concerns were not relat~d to the sequencing issue which subsequently resulted in the shutting down of Surry, Unit 1.
The emergency diesel generator issut: was studied in response to Information Notice 85-91. Following a review of NRC Informa-tion Notice 85-91, VEPCO discovered a design deficiency in the station emergency diesel generators at Surry, Unit 1 and made the decision to shut down Surry, Unit 1 to correct this deficiency.
When a licensee receives an NRC Information Notice, it is incumbent upon the licensee to review it for applicability to their plant and it is expectec that they take appro-priate corrective action.
The information presented to the NRC, in a conference call the night Surry, Unit 1 was shut down, indicated that a significant concern existed with the load-sequencing capability of the emergency di ese 1 generators.
Quest ion 3 Should the Company have considered performing the EOG modifications at some other time (for example, during a future refueling/maintenance outage)?
Answer 3 At the time, the design deficiency identified above represented a significant concern, in that it appeared that the facility was being operated outside the design basis. Therefore, VEPCO acted responsibly in shutting down Unit 1 to correct this issue.
Que5tion 4 Did Virginia Power overreact in shutting aown Surry Unit 1?
Answer 4 No, it was prudent of VEPCO to shut down to correct this deficiency.
The NRC has established minimum safety and operatioral limits; however, a 11 operating licensees are enc*ouraged to exceed these minimum require-ments should there be any questions concerning any adverse impact on the health and safety of the ge11~ral public.
QuE:stion 5 What estabiishes the need for procedural guidance for work in a nuclear facility?
(Please submit any writtt=n document).
Answer 5 The procedural guidance for work in a nuclear facility is provided in Regulatory Guide 1.33, 11Quality Assurance Program R1::quirements (Operation)"
(copy attached).
However, the specific re:quirements for the Surry Station are specified in Section 6.4 of the Surry Plant Technical Specifications
&rid in 10 CFR Part 50, Appendix B, Criterion V.
Copies of these documents are also attached.
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Question 6
~~hat establishes the requirement for identification tags on system valves?
(Please submit any written documentation).
Answer 6 Criterion VIII of 10 ~FR Part 50, Appendix B specifies the measures to be established for the identific~tion and control of materials, parts and components such as valves.
Components in the field must match the drawing identification information so that procedures used by the operators for maintenance, surveillance and opera ti on of the systems can be properly executed.
For example, if a valve did not have a correct identification tag it could lead to installation of a valve in the wrong piping location and could result in serious consequences if left uncorrected. Therefore, the licensee could be cited for non-conformance with the above regulation.
A copy of this section of the regulation is attached.
Attachments:
- 2.
Section 6.4 of Surry Technical Specifications
- 3.
Criterion V of 10 CFR Part 50, Appendix B
- 4.
Criterion VIII of 10 CFR Part 50, Appendix B