ML19343C101
| ML19343C101 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 02/09/1981 |
| From: | Mroczka E NORTHEAST NUCLEAR ENERGY CO. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| MP-1-1710, RO-80-19-IX-1, NUDOCS 8102180640 | |
| Download: ML19343C101 (3) | |
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N3Ti'E:E!IE!i'i' Wi'[2.5'i'E55fi PO Box 270 h
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February 9, 1981 Mr. Boyce H. Grier MP 1710 Director, Region I Office of Inspection and Enforcement U.S. fluclear Regulatory Commission 63T Park Avenue King of Prussia, Pennsylvania 19406
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Reference:
Provisional License DPR-21 Docket flumber 50-245 Reportable Occurrence R0-80-19/IX-1 (Update Report)
Dear Mr. Grier:
This letter forwards an updated Licensee Event Report for Reportable Occurrence R0-80-19/IT, submitted on flovember 20, 1980 pursuant to the require-ments of the Millstone Unit 1 Technical Specifications, Section 6.1.1.9.b.
An additional three copies of the report are enclosed.
Yours truly, NORTHEAST NUCLEAR ENERGY COMPANY
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E.
. Mroczka Station Superintendent Millstone Nuclear Power Station EJt1/MJB/jeb*
Attachment:
LER R0-80-19/IX-1
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Director, Office of Inspection and Enforcement, Washington, D.C. (30) cc:
Director, Office of Management Information and Program Control, Washington, D.C. (3)
U.S. fluclear Regulatory Commission, C/0 Document fianagement Branch, Washington, D.C. 20555 c
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ATTACHMEfiT TO LER 80-19/IX-1 (UPDATE REPORl)
NORTHEAST NUCLEAR EftERGY COMPAllY MILLSTONE fiUCLEAR PONER STATION-UNIT 1 PROVISIONAL LICEftSE fiUMBER DPR-21 DOCKET fiUMBER 50-245 IDEllTIFICATI0!i 0F OCCURREftCE Performance of systems were discovered that require corrective measures to prevent operation in a canner less conservative than assumed in the Safety Analysis Report.
CONDITIONS PRIOR TO OCCURRENCE Prior to the occurrence the plant was shut down for a planned refueliag outage; the Isolation Condenser System was out of service for performance of Class II
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Inservice Inspection.
DESCRIPTION OF OCCURREfiCE On fiovember 6,1950 at 0925 hours0.0107 days <br />0.257 hours <br />0.00153 weeks <br />3.519625e-4 months <br /> during Class II Inservice Inspection of the Isolation Condenser System, liquid penetrant examination of the inside diameter of the steam supply piping nozzle-to-isolation condenser vessel weld revealed circumferential cracking on both sides of the weld in the heat affected zone.
One of these cracks has been confirmed to extend around the circumference with a maximum penetration of 50 percent.
APPARENT CAUSE OF OCCURREliCE The results of metallurgical analysis of the piping section in question indicated the cause of failure to be primarily Intergrannular Stress Corrosion Cracking (IGSCC), however substantial transgrannular cracking was also evident.
ANALYSIS OF OCCURRENCE The Isolation Condenser System is provided for core decay heat removal following -
reactor isolation and scram, and is therefore not required to be operable at the present time.
Degradation of the weld in question did not result in a condition that-has not been previously analyzed.
CORRECTIVE ACTI0fi Following identification of the failure mode of the weld in. question, all accessible welds in the isolation condenser supply and return. lines were inspected using ultrasonic testing techniques specially developed for detection of IGSCC.
In addition, welds on other service sensitive piping were reinspected using this technique to confirm and/or evaluate reflectcrs identified during the Inservice Inspection Program.
Defective sections of the affected systems are being 66 3
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2 repaired or replaced in accordance with Section III and Section XI of the ASME Boiler and Pressure Vessel Code and NUREG 0313 Revision I, returning them to their original design integrity.
A deficiency summary follows; detailed results of all inspections, evaluations and dispositions will be submitted with the Inservice Inspection Summary Report.
SYSTE!i AFFECTED AREA CORRECTIVE ACTION Isolation Condenser 1.
Supply piping at the isolation Replacement condenser: both nozzle safe ends and piping up to and including the first cibou'(Class II).
2.
Supply piping from the reactor Replacement vessel nozzle safe end to the containment penetration (Class I).
3.
Supply piping from the containment Replacement penetration to the second isolation yalyc (Class I).
4.
Return line segment, removed to Replacement internally inspect adjacent welds (Class I).
5.
Return line segment, removed to Replacement internally inspect adjacent welds (Class I).
6.
Process pipe to flued head weld Repair on the isolation condenser supply containment penetration (Class I).
Piping from the suction side of Replacement the reactor recirculation system to the shutdown colling supply inboard isolation valve (Class I).
Cleanup 1.
Piping-frcm the shutdown cooling Replacement line to the cleanup manual isolation valve (Class I).
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