ML18153C673
| ML18153C673 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 07/08/1991 |
| From: | Buckley B Office of Nuclear Reactor Regulation |
| To: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| TAC-65840, NUDOCS 9107170311 | |
| Download: ML18153C673 (3) | |
Text
Docket Nos. 50-280 and 50-281 Mr. W. L. Stewart Senior Vice President Virginia Electric and 5000 Dominion Blvd.
Glen Allen, Virginia
Dear Mr. Stewart:
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SUBJECT:
SURRY UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION RELATING TO APPENDIX R - MULTIPLE HIGH IMPEDANCE FAULTS (TAC NOS. 65840 AND 65841)
The NRC staff has reviewed you submittal dated December 19, 1990, and finds that additional information, delineated in the enclosure, is necessary in order to continue our evaluation.
Please provide.the requested information within 30 days of receipt of this letter to enhance timely closure of this issue.
This requirement affects fewer than 10 respondents and, therefore, is not subject to Office of Management and Budget Review under P.L.96-511.
Enclosure:
As stated cc w/enclosure:
See next page Sincerely, Original si.g11ed by Bart C. Buckley, Senior Project Manager Project Directorate II-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation OFC
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,i Mr. W. L. Stewart Virginia Electric and Power Company cc:
Michael W. Maupin, Esq.
Hunton and Williams Post Office Box 1535 Richmond, Virginia 23212 Mr. Michael R. Kansler, Manager Surry Power Station Post Office Box 315 Surry, Virginia 23883 Senior Resident Inspector Surry Power Station U.S. Nuclear 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 Dr. W. T. Lough Virginia State Corporation Commission Division of Energy Regu_lation Post Office Box 1197 Richmond, Virginia 23209 Regional Administrator, Region II U.S. Nuclear Regulatory Commission 101 Marietta Street N.W., Suite 2900 Atlanta, Georgia 30323 C. M. G. Buttery, M.D., M.P.H.
State Health Co111nission Office of the Commissioner Virginia Department of Health P.O. Box 2448 Richmond~ Virginia 23218 e
Surry Power Station Attorney General Supreme Court Building 101 North 8th Street Richmond, Virginia 23219 Mr. E. Wayne Harrell Vice President - Nuclear Operations Virginia Electric and Power Company 5000 Dominion Blvd.
Glen Allen, Virginia 2~060 Mr. J.P. O'Hanlon Vice President - Nuclear Services Virginia Electric and. Power Company 5000 Dominion Blvd.
Glen Allen, Virginia 23060 Mr. Martin Bowling Manager - Nuclear Licensing Virginia Electric and Power Company 5000 Dominion Blvd.
Glen Allen, Virginia 23060
e REQUEST FOR ADDITIONAL INFORMATION RELATING TO THE SURRY, UNITS 1 AND 2 APPENDIX R MULTIPLE HIGH IMPEDANCE FAULT SUBMITTAL DOCKET NUMBERS 50-280 AND 50-281 ENCLOSURE We have reviewed the Appendix R multiple high impedance fault submittal dated December 19, 1990, which was provided for the Surry Nuclear Station. Information in this submittal clearly suggests that a fire area by fire area analysis for all Appendix R related associated circuits was not performed.
Further, the submittal contains general concluding statements without providing supporting factual information for these statements.
In view of these items, we request the following additional information.
- 1.
The Appendix R high impedance fault submittal indicates that 480 Vac motor control centers (MCCs) supply a great diversity of loads located in various plant locations.
In addition, this submittal also indicates it is expected that the Unit 1 and Unit 2 480 Vac MCCs supply like unit loads located in different plant areas with power often routed in different directions. Further, the submittal indicates that it would be difficult to ascertain the physical locations of the 480 Vac MCC circuits and predict their operation.
In view of these expectations and uncer-tainties, provide additional supporting information for the concluding statement that power engineering believes that load diversity and the relatively low (50A or less) trip ratings of many of the 480 Vac MCC breakers limit the potential for tripping due to multiple high impedance faults.
- 2.
The submittal section addressing the 120 Vac vital bus system notes that the 120 Vac vital buses supply a limited number of loads generally located in the control room and emergency switchgear room (including the instrument rack room).
In addition, this submittal section contains the statement 11 though there are a number of associated circuits, there are expected to be few circuits not directly unit related and, therefore, routed into common areas."
We interpret the above to mean that there are a number of 120 Vac associated circuits in the control room and emergency switchgear room, however most of these associated circuits are expected to be specifically related with either Unit 1 or Unit 2.
Verify or clarify this interpretation and provide additional supporting infor-mation for the expectation that there are few circuits not directly unit related and as such few circuits routed into common areas.
- 3.
Miscellaneous communication equipment power supplies are: a Unit 1 120/240 Vac semi-vital bus, a Unit 1 120/240 Vac heat trace panel, and a Unit 2 120 Vac communication panel.
For these Appendix R power sources, the submittal indicates it is expected that many of the associated circuits supplied by them are local, while others enter various plant areas.
On the basis of this expectation, it is assumed in the submittal that a*
sufficient number of associated circuits from one supply do not enter the redundant power supply fire area to warrant concern for multiple high impedance faults.
Provide additional factual information for the above expectation and as such the resulting assumption.