ML20112G025
| ML20112G025 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 12/28/1984 |
| From: | Haynes J SOUTHERN CALIFORNIA EDISON CO. |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| NUDOCS 8501160152 | |
| Download: ML20112G025 (2) | |
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Southern California Edison Companyy 95g 3, fy n p SAN ONOFRei. NU C L EA R GENER A TING S T A TION P.o. sox its S AN CLEMENTE. C ALIFORNI A 92672 f@ */ j
. J. G. H AYN ES vetapwoNs December 28, 1984
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U.S.-Nuclear Regulatory Commission Office of Inspection and Enforcement Region V 1450 Maria Lane, Suite 210
- Walnut Creek, California 94596-5368 LAttention:
Mr. J. B Martin, Regional Administrator
Dear Sir:
Subject:
Docket Nos. 50-361 and 50-362 Special Report - Seismic Instrumentation San Onofre Nuclear Generating Station, Units 2 and 3 Pursuant to Section 6.9.2 of Appendix A, Technical Specifications to Facility Operating Licenses NPF-10 and NPF-15 for San Onofre Units 2 and 3 respectively, this Special Report is being submitted as required by Action Statement 'a' associated with Limiting Condition for Operation (LCO) 3.3.3.3.
This Action Statement requires that:a Special Report be prepared and submitted to the Commission within 10 days after any of the raismic instrumentation
' listed in Technical Specification Table 3.3-7 is inoperable for more than 30_ days. The cause of the malfunction and plans for restoring the instrument to operate status, are outlined below.
L
_0n December-18, 1984, with Unit 2 defueled and Unit 3 in Mode 1, it was p
discovered that the Seismic Switches, Items 4a and 4b of Technical Specification _ Table 3.3-7, which are common =to both Units 2 and 3, had been calibrated to slightly different setpoints than those specified in Table 3.3-7 since initial startup of Unit 2 in July 1982. The procedural setpoints used to date are as specified in the original design requirements supplied to the
-vendor.
The_ variance between the Technical Specification setpoints ara the original design requirement setpoints results in a slight degradation in threshold
' sensitivity to seismic events. An investigation as to the source of the present Technical Specification calibration requirements and justification as-to why they are different from original design setpoints is in progress. We
.have concluded that.the ability of the instruments to respond to and record a significant seismic event was not affected by this condition. As corrective action, the procedure _has been changed to reflect current Technical Specification calibration requirements and the seismic switches have been recalibrated.
8501140152 841228-1 PDA ADOCK 05000361
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. Mr. J. B.~ Martin..
There was no impact on plant operation or the health and safety of plant personnel or the public as a result of the instruments' inoperability.
If there are any questions regarding the above, pleast contact me.
Sincerely, t/N -
+
cc:
F.' R. Huey (USNRC Senior Resident Inspector, Units 1, 2, and 3)
J. P. Stewart (USNRC Resident Inspector, Units 2 and 3)
U.S.; Nuclear Regulatory Commission Document Control Desk Institute of Nuclear Power Operations (INPO) 1 7
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