ML20038A692
| ML20038A692 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 10/30/1981 |
| From: | Papay L SOUTHERN CALIFORNIA EDISON CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8111160178 | |
| Download: ML20038A692 (4) | |
Text
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Docket Nos. 50-361/362
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50.55(e) Report Southern Califomia Edison Company c::CE P O. BOX 8 0 0 2244 WALN UT G ROVE AVE N U E ROS EM EAD, CALirORNIA 91770 p
October 30, 1981
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Dear Mr. Engelken:
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Subject:
Docket Nos. 50-361 and 50-362 San Onofre Nuclear Generating Station, Units 2 and 3 In a letter to your office dated July 23, 1981, we identified a Condition which we considered reportable in accordance with 10CFR50.55(e).
The Condition concerns the results of a type test of a pressure relief valve manufactured by Dresser Industries which was conducted by Electric Power Research Institute under a joint utility test program.
An interim report was transmitted to you by our letter of August 19, 1981.
The testing required to resolve the Condition and determine necessary corrective action has been completed.
Enclosed are twenty-five (25) copies of a final report entitled, " Final Report on Pressurizer Safety Valve Operability Ins tabilities During '"es t, San Onofre Nuclear Generating i
Station, Units 2 and 3."
4 If you have any questions regarding this report, we would be happy to discuss them at your convenience.
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Very truly yours, j/ J/
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Enclosures cc:
Victor Stello (NRC, Director I&E)
A.
E. Chaffee (NRC, San Onofre Units 2 and 3) 77 9
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S ADOCK 05000361 PDR
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FINAL REPORT ON THE PRESSURIZER SAFETY VALVE OPERABILITY INSTABILITIES DURING TEST SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3 INTRODUCTION This report is submitted pursuant to 10CFR50.55(e).
It describes a condition involving operating instabilities of a Dresser Industries spring loaded safety valve which were exhibited i
during type tests being conducted by Electric Power Research Institute (EPRI).
The valve is the same model supplied for use as pressurizer safety valve on San Onofre Units 2 and 3.
By letter dated July 23, 1981 Southern California Edison confirmed notification to the NRC of this condition.
By subsequent letter dated August 20, 1981, SCE submitted an interim report in accordance with 10CFR50.55(e).
The interim report included a description of the deficiency, an analysis of the safety implications of the condition and a summary of the corrective action then being taken.
This final report summarizes subsequent testing, analysis and corrective action accomplished.
BACKGROUND The background o'
.he condition, cluding the circumstances of the original test ouring which the operational instabilities 4
were exhibited, was given in the interim report.
Since that report, additional testing and analysis have been performed to determine the effect and the limiting boundaries of the parameters which contribute to the instabilities.
DISCUSSION The following discussion i.e responsive to 10CFR50.55(e) (3).
Descripticn of Deficiency During the original test the valve opened at a pressure slightly below set pressure, oscillated between full open and full closed positions for about 2 minutes, reseated with minor leakage at a pressure below that assumed in the FSAR analysis, and then reopened for a short period of time at a pressure approximately 14% below set point.
Some damage to internal surfaces of the valve were found subsequent to the test.
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FINAL REPORT ON THE PRESSURIZER SAFETY VALVES..... (cont. )
Analysis of Safety Implications The observed operation of the valve during the original test was not in conformance with the ASME BPV Code and was inconsistent with the licensing assumption that the valve would close at 2400 psia.
However, as noted in the interim report, the increased blowdown experienced in the test would not have resulted in either an uncontrolled depressurization or an overcooling of the reactor coolant pressure boundary.
Corrective Action Subsequent to submittal of the interim report, a valve operating test has been conducted with inlet piping reduced to the minimum length which would be feasible in construction.
The ring adjustments of the valve were set to reseat at a blowdown pressure which will be compatible with both stable operation and maintaining dry saturated steam discharge.
Stable operation with this configuration has been confirmed recently in the EPRI Test Program.
The installed inlet piping has been reduced in length from approximately 18 feet to the configuration shown in the attached sketch.
The ring adjustments of the installed valves will be set in accordance with criteria established in the successful test.
The above described actions will be accompitshed prior to fuel load.
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'F/NAL REPORT ON THE PRESKURIZER 5AFETY VAL VE OPERAB/L/TY /NSTABILITIE5 OUR/NG TEST PRE 550R/ZER SAFETY VML VE
/NL ET P/ PIN 6 S4N ONOFRE UN/T52 & 3 PRESSURIZER SAFETY VAL VE
/NLET FLANGE MATING
! SURFACE
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NOTES' :
/. ALL P/ PIN 6 IS G-/NCH f
6 " T YP.
SCHEDUL E /6 0.
2.'roTAL LEN6TH OFINLET P/P/N6 9 " TYP.
FROM /D of PRES 5URIZER 70
/4L VE /NLET FL AN6E MA T/N6 V
SURFACE = 3.6 FT a"
rre PRES 50R/ZER WALL
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