ML18116A286
| ML18116A286 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 07/13/1979 |
| From: | Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 530, NUDOCS 7908080151 | |
| Download: ML18116A286 (4) | |
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July 13, 1979 Mr. James P. O'Reilly, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Region II 101 Marietta St., Suite 3100 Atlanta, Georgia 30303
Subject:
Dear Mr. O'Reilly:
Serial No.
530 PO/FHT:ye Docket Nos. 50-280 50-281 50-338 50-339 License Nos. DPR-32 DPR-37 NPF-4 CPPR-78 We have reviewed IE Bulletin 79-13, Cracking in Feedwater System Piping, and provide the attached responses to Item 5 for Surry Units 1 and 2 and North Anna Units 1 and 2.
If you have any questions or require additional information, please contact this office.
cc:
NRC Office of Inspection & Enforcement Washington, D. C. 20555 Very truly yours,
~- })?. x/t~t£~J<'J C. M. Stallings Vice President-Power Supply and Production Operations a~~
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Attachment, RESPONSE TO IE BULLETIN 79~13, ITEM 5 FOR SURRY POWER STATION UNITS 1 AND 2 Page 1
of 3
Sa.
Request:
Provide schedu1.e for inspection of feedwater piping welds.
Response: Both units are at cold shutdown.
Radiography of all feedwater welds inside Unit 1
- Containment is in progress a~~J should be complete within 25 days.
Operability "and conformance of pipe sup-ports bas been verified for Unit 1 *. Radiography of Unit. 2 feed-water piping welds will be completed prior to unit startup
- following the Steam Generator Replacement Outage.
Inspection of supports and snubbers will be completed for Unit 2 teed system piping in conjunction with the Pipe Stress Reanalysis Program currently in progress.
Sb.
Request:
Address adequacy of operating and emergency procedures to recog-nize and respond to a feedwater line break accident.
Response: We have reviewed the procedures for main steam line rup_ture and loss of feedwater flow.
It is apparent that it would be difficult in many cases to quickly distinquish between a feed-water line break and a main steam line break.
However, since the immediate operator actions are the same for either case, this does not present a procedural problem.
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Our procedures review has identified the need for procedural improvements to give more detailed guidance on the isolation of feedwater under fee4water line break conditions.
These changes will be completed prior to the start up of either unit.
Sc.
~quest:
Address the methods and sensitivity of detection of feedwater leaks in containment.
Response: Various instrumentation is available for diagnosing a feedwater line break inside containment.
This includes sump level, con-tainment temperature, containment pressure, steam generator level, and feedwater flow.
Annunciation compliments the instru-mentation for each of the above par.ameters for additional indication.
Additionally, containment walk.downs are made every two weeks.
The sensitivity for feedline break detection has not been quantified, howevir, steam flow/feed flow mismatch.
alarms actuate *at.709 x 10 lb/hr flow.
Containment pressure alarms actuate at el psi.pressure rise above setpoint.
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e Attachment, RESPONSE TO IE BULLETIN 79-13, ITEM 5 FOR NORTH ANNA POWER STATION UNITS 1 AND 2 Page 2
of 3
- Sa.
Request:
Provide schedule for inspection of feedwater piping welds.
Response: Feedwater piping and piping to nozzle welds for Unit 1 will be inspected during the refueling outage scheduled to begin Sep-tember 15, 1979.
The inspection will be performed via* radio-graphy during the refueling outage.
A similar inspection was performed on Unit 2 on June 27. 1979.
5b.
Request:
Address adequacy of operating and emergency procedures to recognize and respond to a feedwater line break *accident.
Response: At present, our procedures provide adequate ability to respond to a.feedwater line break accident.
The response to this acci-dent is covered in the procedures for a main steam line rupture and loss of feedwater flow.
(The only apparent problem seems to be differentiating a feedwater line rupture from a main steam line rupture initially.
Changes in the main steam line rupture emergency procedures are being considered to aid personnel in differentiating the two accidents.)
Plant design also aids in accident recovery.
If a rupture to a feedwater line to one steam generator occurs, then auxiliary feed flow is also lost to that generator.
The other two steam generators still receive auxiliary feed flow since we have an auxiliary feed pump lined up to each steam generator.
'Ibis provides a heat sink for the reactor.
Sc.
Request:
Address the methods and sensitivity of detection of feedwater leaks in containment.
Response: The methods used for detecting a feedwater leak inside the containment are as follows:
A)
Increasing containment sump level and containment pressure without a high radiation signal that characterizes a primary leak.
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Increased feed flow with decreasing steam generator level (possible steam flow/feed flow mismatch may. also occur).
c)
Possible increasing pressurizer pressure along with the above conditions.'
If a small leak is suspected, but not *fully identified, a visual inspection could be performed to determine the exact location and appropriate action to be taken.
If a large leak or rupture occurs, the above indications will occur rapidly and appropriate action will be taken either automatic-ally via ESF equipment or by operator action.
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