ML20087M615
| ML20087M615 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 03/26/1984 |
| From: | Gucwa L GEORGIA POWER CO. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| NED-84-043, NED-84-43, TAC-48771, NUDOCS 8403300104 | |
| Download: ML20087M615 (2) | |
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Georgia Power Company 333 Piedmont Avenue
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Atlanta. Georg.a 30308 Telephone 404 5266S?6 Maang Ackfress Post Office Box 4545 Atlanta. Georgia 30302 j
Georgia Power j
L T. Gucwa
" W 8Y-0(3" Manager Nuclear Engineenng nd Chief Nuclear En.;neer March 26, 1984 Director of Nuclear Reactor Regulation Attention: Mr. John F. Stolz, Chief Operating Reactors Branch No. 4 Division of Licensing U. S. Nuclear Regulatory Canission Washington, D. C.
20555 NRC DOCKETS 50-321, 50-366 OPERATING LICENSES DPR-57, NPF-5 EDWIN I. HA701 NUCLEAR PIANT UNITS 1, 2 SAFETY RELIEF VALVE CYCLING PROGRAM Gentlenen:
Correspondence dated July 9,1982, and February 2,1983, fra Georgia Power Omnpany to the NRC-Region II described Safety Relief Valve (SRV) manual l
cycling being done on both Hatch units as a result of SRV high-setpoint drift experienced on Hatch-1 in July 1982. Nine of the eleven SRVs per unit have been manually operated at a nminal 92-day frequcncy under this program.
Since our last correspondence on this topic, the Boiling Water Reactor Owners an investigation Group (BWROG) SRV Setpoint Drift Cmunittee has cmpleted into the phenmenon and provided recmaendations for improving valve performance.
The investigation progran and resulting recmmendations were the topic of an information meeting with the NRC, held in the Phillips building in Bethesda on Novenber 10, 1983.
Based upon the results of the BWROG investigation, GPC intends to discontinue the progran of periodic manual operation of SRVs. This decision is based on the following considerations:
l 1.
Valve cycling was intended to clean a corrosion product from the~ pilot valve disc, and thereby eliminate sticking caused by corrosion bonding.
Later. investigation has shown that the corrosion product is strongly adherent and is not removed by valve operation of short duration. Ionger periods of valve operation are not desirable because of possible adverse plant responses, and erosion of valve parts ' causing prenature leakage.
In the future, any corrosion present -in the disc and seat area will be renoved per BWROG recemendations during periodic recertification of the SRVs.
While there is no assurance that this practice. will totally eliminate setpoint drift due to pilot disc / seat sticking, we are confident 8403300104 840326
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A Georgia Power h Director of Nuclear Reactor Regulation Attention: Mr. John F. Stolz, Chief Operating Reactors Branch No. 4 March 26, 1984 Page 'IVo that frequency and severity of its occurrence will be reduced to an acceptable level. General Electric Capany has agreed to monitor the performance of two stage Target Rock SRVs at Plant Hatch and other BWR plants for a two year period.
Further corrective action will be pursued if improved maintenance does not correct the problem.
2.
%e BWROG investigation results show that the largest contributor to i
setpoint drift is friction between the pilot valve rod and its guide bushing. %e friction is caused by inadquate clearance between these cmponents. The clearance problen will be corrected, and a lubricant will be used per BWROG reccmnendations on all SRVs in service at Plant Hatch.
Cycling of the valves during plant operation is unlikely to reduce friction forces or benefically affect the valve's setpoint.
3.
Investigators frm General Electric Cmpany who conducted the BWROG progran, have concludal that the Hatch-1 event in July 1982 was a unique non-repetitive event probably influenced by a
chenical intrusion which occurred in April, 1982.
It is believed that the chenistry transient accellerated corrosion of the pilot disc and seat and thereby caused sticking.
In the event of such a chenistry transient occurring in the future, appropriate measures will be taken to assure reliable operation of the SRVs.
Corrective measures would involve either manual cycling of the valves after restart, or, in an i
extrene case such as occured in April 1982, refurbishnent of the SRVs.
I 4.
SRV cycling has caused valves to leak prenaturely and has contributed to unwarranted wear on associated caponents.
We will continue to keep you informed of any developnents. Please contact this office if you have any questions or cmsnents.
Yours very truly, fTQ_,w L. T.
Gucwa PLS/nw xc: J.T. Beckham, Jr.
H.C. Nix, Jr.
Senior Resident Inspector - Plant Hatch J.P. O'Reilly - Region II rmns C_
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