ML20202D886
| ML20202D886 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/03/1986 |
| From: | Morgan H SOUTHERN CALIFORNIA EDISON CO. |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| NUDOCS 8607140240 | |
| Download: ML20202D886 (2) | |
Text
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~' UT Southern California Edison Companyfi
'V' SAN ONOFRE NUCLE AR GENERATING ST ATION P O box 120 t
SAN CLEMENTE. CALIFORNI A 92672 TELEPHONE H E. MORGAN 4714) 36s 6241 s'*""'""
July 3, 1986 U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region V 1450 Maria Lane, Suite 210 Walnut Creek, Cali fornia 94596 Attention:
Mr. J. 8. Martin, Regional Administrator
Dear Sir:
Subject:
Docket No. 50-206 Commi tment Clari fica tion San Onofre Nuclear Generating Station, Unit 1 Re ference:
Letter Mr. J. G. Haynes (SCE) to Mr. J. B. Martin (NRC) dated October 26, 1984 The referenced letter indicated that orificed drain valves, downstream of spray header isolation valves, would be installed during the next refueling outage in order to provide a continuous drain path and prevent leakage past the isolation valves resul ting in corrosion in the system and possible blockage in the spray noz71es. Although the orificed drain lines have been installed downstream of each header isolation valve in accordance with our commitment, only the drain line downstream of CV-92 will remain continuously opened. Those downstream of CV-82 and CV-ll4 will remain closed.
CV-92 isolates the Re fueling Water Storage Tank (RWST) s tatic head from spray nozzles located at an elevation below the normal water level in the RWST.
CV-82 and CV-114, however, isolate the RWST static head from spray nozzles located in the containment dome, well above the top of the RWST.
Therefore, leakage through CV-92 would flow by gravity to spray nozzles inside the secondary shield and result in nozzle blockage by oxidation and corrosion product buildup at the nozzle.
Leakage past CV-82 and CV-ll4,
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MR. J. B. MARTIN however, would accumulate in the containment dome spray header riser only, and thus, would never rise to the level of the spray nozzles in the dome.
As such, blockage of spray nozzles downstream of CV-82 and CV-ll4, similar to that which occurred downstream of CV-92, did not occur in the past and is not expected to occur in the future. Because of this configuration, the installation of the drain lines associated with CV-82 and CV-ll4 has only marginal benefit.
Leakage past CV-82 and CV-114 would result in an approximate 25 foot long section of the carbon steel riser being continuously filled with borated water. Recent inspections during drainage of this section of piping have indicated only minor accumulation of corrosion products. Corrosion particle sizes observed at that time were such that blockage of the spray nozzles would not have occured during spray actuation.
Resumption of operation in this condition is therefore considered acceptable for this cycle.
In order to further alleviate any concerns that corrosion products in this section of pipe downstream of CV-82 and CV-114 would accumulate to the extent that dome spray nozzles would be blocked, this portion of the line will be drained at the planned mid-cycle outage and again at the next refueling outage to determine the extent of build up.
If warranted, that section of the header will be replaced with stainless steel pipe or CV-82 and CV-ll4 will be replaced with leak tight valves.
If you have any questions regarding the above please contact me.
Sincerely, yQ&
I cc:
F. R. Huey (USNRC Senior Resident Inspector, Units 1, 2 and 3)
U. S. Nuclear Regulatory Commission Document Control Desk Institute of Nuclear Power Operations (INPO) i
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