05000275/LER-1983-006, Updated LER 83-006/01T-1:on 830510,possible Undersize Condition Discovered on Reactor Coolant Piping Weld WIB-RC-2-17 During Ultrasonic Testing.Weld Confirmed to Be Above Min Wall Requirements Mechanically

Updated LER 83-006/01T-1:on 830510,possible Undersize Condition Discovered on Reactor Coolant Piping Weld WIB-RC-2-17 During Ultrasonic Testing.Weld Confirmed to Be Above Min Wall Requirements Mechanically

ML20078N613
Person / Time
Site:	Diablo Canyon
Issue date:	10/13/1983
From:	Kelly W, Shiffer J PACIFIC GAS & ELECTRIC CO.
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
LER-83-006-01T, LER-83-6-1T, NUDOCS 8310250639
Download: ML20078N613 (3)

LER-2083-006, Updated LER 83-006/01T-1:on 830510,possible Undersize Condition Discovered on Reactor Coolant Piping Weld WIB-RC-2-17 During Ultrasonic Testing.Weld Confirmed to Be Above Min Wall Requirements Mechanically

Event date:
Report date:
2752083006R00 - NRC Website

text

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EVENT DESCRIPTION AND PROSA8LE CONSEQUENCES h I o l2 l l Prior to fuel load, ultrasonic (UT) thickness measurements woro taken on I lo ja l l reactor coolant piping welds to establish baseline data for subsequent NDE inspec- l l a l, l l tions. During these examinations, a possible under size condition was discovered l l o is l l on weld WIB-RC-2-17. Minimum wall thickness by UT measurement indicated that the l l o }6 l l Weld was 0.065 inches below the required thickness of 2.215 inches. Reportable l j o l 7 l l p'er Technical Specification Section G.9.1.12.i . This event has in no way affected l 1 o 18 l l the public's health and safety. l

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CAUSE DESCRIPTION ANO CORRECTIVE ACTIONS 27 l i lo l l This is a final report. Analysi, has shown that UT measurements lack the l lilt ll precision to accurately determine the wall thicknes; of reactor coolant piping weldf lila l l Each weld initially determined to be undersized ba:,ed on UT measurements was l l ils l l confirmed by mechanical measurements to actually be above minimum wall l liI4ll requirements.

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~ ef ATTAC MENT TO LER 83-006/01T-1 i

PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON, UNIT 1 DOCKET NO. 50-275 SUPPLEMENTAL INFORMATION Preliminary measurements obtained during the performance of a Non-Section XI Code ultrasonic thickness testing indicated that a pipe to pipe weld in Reactor Coolant Loop No. 2 between the Reactor Pressure Vessel and the Reactor Coolant Pump may have been less than the design minimum wall thickness of 2.215 inches.

!- A full investigation was. conducted and a report made to the NRC entitled,

" Pacific. Gas and Electric Company's Report on Investigation of Reactor Coolant Pipe Weld Thickness at Diablo Canyon," dated July 1,1983. The report concluded that the latest state-of-the-art ultrasonic measurement techniques

cannot be utilized for precise thickness measurements of stainless steel piping welds which are greater than two (2) inches thick. A full review of 4

quality records and numerous mechanical measurements determined that all reactor coolant piping welds-are above the design minimum wall thickness requirements.

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PACIFIC OAS AND ELECTR,IC C O M PANY PGtNf3 l 77 BEALE STREET SAN FRANCISCO, CALIFORNIA 94106. (415) 781-4211. TWX 910 372-6587 JAMES D SHIFFER $,,g,,

DEPARTMENT OF NUCLEAR PLANT OPERATIONS NUCLEAR POWER GENERATION

} { :f '<.r 4l 130 [ 9 Q'n D October 13, 1983 Mr. John B. Martin, Regional Administrator U. S. Nuclear Regulatory Consnission, Region V 1450 Maria Lane, Suite 210 Walnut Creek, CA 94596-5368 Re: Docket No. 50-275, OL-DPR-76 Diablo Canyon Unit 1 Licensee Event Report 83-006/01T-1 Weld in Reactor Ccclant Loop No. 2

Dear Mr. Martin:

Pursuant to Section 6.9.1.12.i of the Technical Specifications, Appendix A to the Diablo Canyon Unit 1 Operating License, enclosed is a revision to the subject Licensee Event Report containing updated information on welds in the. Reactor Coolant system which were suspected of being below the minimum wall thickness requirements.

This event has in no way affected the public's health and safety.

Sincerely,

~

t.n p Enclosure cc: G. W. Knighton Director, Office of Management Information and Program Control Service List i

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