ML20204C132
| ML20204C132 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 07/24/1986 |
| From: | Mark Miller Office of Nuclear Reactor Regulation |
| To: | Conway R GEORGIA POWER CO. |
| References | |
| NUDOCS 8607310015 | |
| Download: ML20204C132 (4) | |
Text
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Docket Nos.:
50-424 50-425 Mr. Richard Conway Vice President and Project General Manager Georgia Power Company Route 2 Box 299A Waynesboro, Georgia 30830
Dear Mr. Conway:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION REGARDIfN V0GTLE CONFIRMATORY. ITEM 22, "0PERATOR ACTION IN EVENT OF A SMALL-BREAK LCCA" By letter dated June 13, 1986, Westinghouse informed t e NRC staff that manual tripping of residual heat removal (RHR) pumps and manual realignment to the re-fueling water storage tank (RWST) is required following a loss of coolant accident (LOCA) in mode'4 to prevent RHR pump damage and to ensure long term core cooling. The time available to complete realignment was stated to be as little as 3 minutes. Manual operator actions were stated to be required at several plants including Vogtle.
Georgia Power Company's response to confirmatory item 22, " Operator action in event of a small-break LOCA," dated June 13, 1986, assumed immediate actuation of the RHR pumps in the safety injection mode and indicated that the action would be automatic on high containment pressure. This response is not consistent with the June 13 Westinghouse letter. -In order to resolve this issue, you should respond to the enclosed request for additional information as soon as possible.
In light of this new information which raises a new concern, the staff does n'ot consider this issue to be of a confirmatory nature. Therefore, confirmatory item 22 including the issue ~of potential RHR pump damage resulting from a LOCA (large-or small-break) in mode 4 will be addressed as an open item in Vogtle SSER 3.
If-there are any questions on this matter, contact me at (301) 492-7357.
Sincerely, l
1-Melanie A. Miller, Project Manager
(
PWR Project Directorate #4 l
Division of PWR Licensing-A l
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h' o Mr. R. E. Conway Georgia Power Company Vogtle Electric Generating Plant cc:
Mr. L. T. Gucwa Resident Inspector Chief Nuclear Engineer Nuclear Regulatory Commission Georgia Power Company P. O. Box 572 P.O. Box 4545 Waynesboro, Georgia 30830 Atlanta, Georgia 30302 Mr. Ruble A. Thomas Deppish Kirkland, III, Counsel Vice President - Licensing Office of the Consumers' Utility Vogtle Project Council Georgia Power Company /
Suite 225 Southern Company Services, Inc.
32 Peachtree Street, N.W.
P.O. Box 2625 Atlanta, Georgia 30303 Birmingham, Alabama 35202 James E. Joiner Mr. Donald O. Foster Troutman, Sanders, Lockennan, Vice President & Project General Manager
& Ashmore Georgia Power Company Candler Building Post Office Box 299A, Route 2 127 Peachtree Street, N.E.
Waynesboro, Georgia 30830 Atlanta, Georgia 30303 Douglas C. Teper Mr. J. A. Bailey Georgians Against Nuclear Energy Project Licensing Manager 1253 Lenox Circle Southern Company Services, Inc.
Atlanta, Georgia 30306 P.O. Box 2625 Birmingham, Alabama 35202 Ernest L. Blake, Jr.
Bruce W. Churchill, Esq.
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Shaw, Pittman, Potts and Trowbridge Tim Johnson 1800 M Street, N.W.
Executive Director Washington, D. C.
20036 Educational Campaign for a Prosperous Georgia Mr. G. Bockhold, Jr.
1083 Austin Avenue, N.E.
Vogtle Plant Manager Atlanta, Georgia 30307 Georgia Power Company Route 2, Box 299-A Billie Pirner Garde Waynesboro, Georgia 30830 Citizens Clinic Director Government Accountability Project Regional Administrator, Region II 303 10th Street U.S. Nuclear Regulatory Commission Augusta, Georgia 30901 101 Marietta Street, N.W., Suite 2900 Atlanta, Georgia 30323
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Enclosure Request for Additional Information Vogtle Confirmatory Item 22, " Operator Action in Event of a SBLOCA" The staff's review of a letter from Westinghouse Electric Corporation to the NRC (Reference 1) finds that it is not consistent with Georgia Power Company's response to staff questions regarding postulated loss of coolant accidents (LOCAs) during shutdown at Vogtle (Reference 2). The Westinghouse letter concludes that to mitigate a LOCA during mode 4 it is necessary for certain operator actions to be completed as stated below.
(1) The residual heat removal (RHR) pumps must be tripped prior to the system voiding.
(2) The RHR pumps must be aligned to the refueling water storage tank (RWST) for safety injection and safety injection must be manually initiated.
The RHR pumps and high pressure safety injection (HPSI) pumps must be returned to operation within 3 to 5 minutes for breaks greater than 3 inches in diameter.
The Westinghouse letter further indicates that without inmediate operator action to trip the RHR pumps which are operating prior to the LOCA, the pumps may be damaged from loss of flow.
The June 13 letter states Westinghouse's position that large-break LOCAs are not credible while in mode 4.
The staff has not previously accepted this position.
Appendix C of your response (Reference 2) to staff questions assumes immediate safety injection actuation of an RHR pump following a large break LOCA with the plant in mode 4 and does not evaluate required operator actions or associated actuation delays.
The staff requires additional information as follows:
a.
Provide an evaluation of potential damage to the RHR pumps from loss of flow and net positive suction head (NPSH) in the event of a LOCA while in mode 4.
Evaluate the time available to the operator to trip the RHR pumps as a function of postulated break size.
Inc'ude the time from initiation of the break until adverse conditions occur in the RHR pump suction and the additional time before damage to the pump would occur, b.
Describe all operator actions required in realigning the RHR pumps to the RWST. Provide an evaluation of the time required for each action.
Describe operator procedures and training to mitigate LOCAs in mode 4 including the instrumentation that is relied upon to implement these procedures.
c.
Reference 1 indicates that the RHR pumps could be damaged if not tripped immediately following a LOCA.
If this occurred, describe other systems and procedures which would be utilized to provide for long-term core cooling.
1 p'
d.
To ensure availability of at least one train of low pressure injection, discuss the desirability of Technical Specification requirements that two trains of RHR be operable while in mode 4 with only one train in operation.
The other train would be in standby and, therefore, available in the event that the first train were damaged from loss of flow during a postulated LOCA.
e.
Reference 1 indicates that as little as 3 minutes may be available to restore the RHR pumps for safety injection and to actuate the high head safety injection pumps following breaks larger than 3 inches while in mode 4.
Provide an evaluation of available time to actuate safety injection before acceptable core damage limits are exceeded.
Provide the available time as a function of break size for mode 4 operation.
References 1.
E. P. Rahe, Westinghouse, letter to J. Taylor, NRC, June 13, 1986.
2.
J. A. Bailey, Georgia Power Company, letter to H. Denton, NRC, "SER Confirmatory Item 22: Small Break LOCA," June 13, 1986.
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