ML20195K051

Oyster Creek,12R Outage,Igscc Insp/Stress Improvement Plans

ML20195K051
Person / Time
Site:	Oyster Creek
Issue date:	05/26/1988
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20195K049	List: ML20195K045 ML20195K051
References
PROC-880526, NUDOCS 8806290331
Download: ML20195K051 (11)

Text

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4 OYSTER CREEK 12R OUTAGE  !

i IGSCC INSPECTION / STRESS IMPROVEMENT PLANS l

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l GPU NUCLEAR CORP.

MAY 26,1988 i

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G806270331 880616 PDR hDOCK 0500021t)

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. 1 OUTLINE 3 OYSTER CREEK IGSCC EXPERIENCE l 12R OUTAGE INSPECTION AND STRESS IMPROVEMENT PLANS BASIS FOR INSPECTION PLAN PERCENTAGES TECHNICAL BASIS FOR INSPECTING (100% OF STRESS IMPROVED WELDS GENERAL ALARA TECHNICAL COMPARISON OF GPUN PLAN AND 84-11 REINSDECTIONS NEW INSPECTIONS POST-STRESS IMPROVEMENT INSPECTIONS

SUMMARY

AND CONCLUSIONS i

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BACKCROUND/ HISTORY OF WELDS IN 84-11 SCOPE -

NO ICSCC DETECTED PI 10R REINSP PI TOTAL 10R IN llR TOTAL ICSCC DETECTED, ICSCC DETECTED, SYSTEM WELDS NI* ONLY IIR ONLY INSP NOT REPLACED REPLACED RECIRC. 89 20(5) 2 28 36 66 3 - 2 OL, 1 SI O SHUTDOWN COOLING 14 8(0) 0 2 4 6 0 0 CORE SPRAY 26 18(0) 0 1 7 8 0 0 RWCU 51 35(5) 6 2 8 16 0 0

ISO CONDENSER l INSIDE 2ND VALVE 58 34(14) 12 6 6 24 0 0 i

OUTSIDE 2?JD VALVE 131 19(2) 54 39 0 93 19 - All OL 9 w/ IGSCC. 17 new I welds in 10R CLOSURE HEAD 8 8(0) 0 0 0 0 0 TOTAL 377 142(26) 74 78 61 213 22 o UNINSPECTABLE WELDS IN "( )"

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GPUN 12R IGSCC INSPECTION PLAN TOTAL BUTT PREV. (GSCC SYSTEM WELDS WELDS INSP. WELDS RECIRC 89 10 7 3 SHUTDOWN COOLING 14 3 0 0 CORE SPRAY 26 9 0 0 RWCU 51 10 0 0 ISC CONDENSER INSIDE 58 14 3 0 OUTSIDE 1 31 15 11 4 CLOSURE HEAD 8 2 0 0 TOTAL 377 63 17 7 l

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, 12R SI PLAN 2 DECIRC SAFE ENDS (4 WELDS) 2 CORE SPRAY SAFE ENDS (4 WELDS) 2 ISO. CONDENSER SAFE ENDS (4 WELDS) 22 CORE SPR AY PIPE WELDS (8" NPS) 9 ISO CONDENSER PlPE WELDS INSIDE DRYWELL (10" NPS)

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, BASIS FOR GPUN's 12R PLAN FOCUS ON WELDS NOT INSPECTED IN 10R (TO 82-03) OR 11R (TO 84-1 1)

PERCENTAGES ARE A COMBINATION OF 84-11 AND DRAFT REV. 2 OF NUREG 0313 1

STRESS IMPROVED IN 11R (RECIRC-61, ALL POST-Si INSPECTED): 10% (50% EVERY 10 YRS.)

INCLUDES WELDS REQUIRING ADDITION AL EXAMS TO DISPOSITION. I REMAINDER OF SYSTEMS INSIDE 2nd VALVE: 20%, MOSTLY UNINSPECTED IN 10R OR 11R ISO CONDENSER OUTSIDE 2nd VALVE: 10% (ALL INSPECTABLE WELDS INSPECTED IN 10R,17 NEW WELDS INSTALLED IN 10R)

IGSCC FOUND IN 11R: FOUR WELDS (100%,3 IN REClRC.,1 IN IC OUTSIDE ?.ND VALVE; 2 WERE INSPECTED IN 10R, DISPOSITIONED AS GEOMETRY) 3 M OF THE OL's DEPOSITED IN 10R (IC): 10% l ALL SAFE END WELDS (12) INSPECTED AFTER SI  !

ALL NOT PREVIOUSLY INSPECTED DUE TO AS-WELDED CLADDING ON OD, SAMPLE EXPANSIONS, SHOULD IGSCC BE FOUND, IN ACCORD ANCE WITH 84-11 l

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, BASIS FOR GPUN's 12R PLAN (cont'd) 84-11 REQUIRED REINSPECTION OF WELDS INSPECTED TO 82-03  !

84-11 INSPECTIONS PERFORMED UNDER PERSONNEL REQU ALIFICATION PROGRAM VERIFIED ADEQUACY OF 82-03 INSPECTIONS HWC TO BE IMPLEMENTED START OF CYCLE 12 NWC CONDUCTIVITY SINCE 82-03 INSPECTIONS EXCELLENT AVER AGE 4 0.11 pS/cm., FEW UPSETS  ;

CRACK GROWTH VERY SLOW UNDER THESE CONDITIONS DR AFT REV. 2 OF NUREG-0313 DOES NOT REQUIRE SUCCESSIVE-OUTAGE INSPECTION OF CATEGORY D WELDS i .

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, INSPECTION AFTER STRESS IMPROVEMENT PLAN 2 RECIRC SAFE ENDS (4 WELDS)- INSPECT AFTER SI-2 CORE SPRAY SAFE ENDS (4 WELDS)-INSPECT AFTER Si 2 ISO. CONDENSER SAFE ENDS (4 WELDS)-INSPECT AFTER Si 22 CORE SPRAY PlPE WELDS (6" NPS) INSPECT 5, AIM TO PERFORM AFTER SI 9 ISO CONDENSER PIPE WELDS (10" NPS)- INSPECT 5, AIM TO PERFORM AFTER Si BASIS FOR INSPECTING < 100% OF SI'd WELDS GENERAL PHILOSOPHY - BETTER TO SI AND INSPECT < 100% THAN NOT PERFORM St.

ALARA - WELD CROWN REDUCTION AND INSPECTION HAVE BIG IMPACT ON DOSE (~ 18 MAN-REM FOR CURRENT PIPE SI SCOPE) 4531 H

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BASIS FOR INSPECTING < 100% OF SI'd WELDS TECHNICAL GROWTH OF EXISTING CRACKS IN PIPE <12" NPS l' AS-WELDED: SHALLOW CR ACKS COULD GROW TO

UNACCEPTABLE DEPTH IN < 1 CYCLE.

AS SI'd: CRACK MUST BE DEEP (> 50% TW) TO GROW i (BY ANALYSIS)

GPUN UNAWARE OF GROWTH OF CRACKS IN SI'd WELDS i

GPUN UNAWARE OF NEW CRACKING IN SI'd WELDS WITH NO j INDICATlOM3 IN PREVIOUS INSPECTIONS

} F-REYlOUS FINDINGS OF "NEW" CR ACKS IN Sl'd WELDS ATTRIBUTED TO MISlNTERPRETATION OF PREVIOUS i INSPECTION DATA.

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• GPUN INSPECTION PLANS INCLUDE REINSPECTION OF

WELDS WITH INDICATIONS CONSIDERED POTENTIAL, BUT ONLY SLlGHTLY SO, "MIS-CALLS" i

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l GPUN PLAN AND 84-11 DIFFERENCES THESE ARE DIFFERENCES BETWEEN OUR APPROACH TO APPLYING 84-11 TO A SECOND OUTAGE VS. LITERAL INTERPRETATION OF l DOCUMENT INTENDED TO APPLY TO ONE OUTAGE.

REINSPECTIONS 84-11 REQUIRES 20%, NLT 2 GPUN: 10% of RECIRC (SI'd),10% ISO CONDENSER OUTSIDE DRYWELL (ALL INSPECTED IN 10R)

NEW INSPEC1!ONS 84-11 REQUIRES 20% OF THOSE WELDS NOT PREVIOUSLY INSPECTED, NLT 4 GPUN: 20% OF TOTAL SYSTEM WELDS, NOT PREVIOUSLY INSPECTED POST-El INSPECTIONS .

84-11 IMPLIES 100%

GPUN: 47% IN 12R (20 OF 43), BUT 88% (38 OF 43) WILL HAVE BEEN INSPECTED IN 10,11, AND 12R RECIRC: 4 OF 4 TO BE INSPECTED IN 12R CORE SPRAY 9 OF 26 TO BE INSPECTED IN 12R 8 OF 26 WERE INSPECTED IN 11R (2 WERE REPEATS OF 10R INSPECTION) 9 NOT INSPECTED FOR IGSCC ISO CONDENSER INSIDE DRYWELL 9 OF 13 TO BE INSPECTED IN 12R 4 OF 13 WERE INSPECTED IN 11R (2 WERE REPEATS OF 10R INSPECTION) 4531H

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SUMMARY

AND CONCLUSIONS l PLAN TO INSPECT AT LEAST 20% OF WELDS NOT PREVIOUSLY  :

INSPECTED IN 10R OR 11R.  !

REINSPECTION OF 10% OF WELDS PREVIOUSLY INSPECTED OCCURS IN SYSTEMS WHERE ALL WELDS HAVE RECEIVED AT i LEAST ONE INSPECTION IN 10R AND/OR 11R. I l

RECIRC AND ISO CONDENSER OUTSIDE DRYWELL I GPUN SATISFIED WITH ADEQUACY OF 82-03 INSPECTIONS GOOD WATER CHEMISTRY IN CYCLES 10 AND 11 SIGNIFICANTLY REDUCES POTENTIAL FOR NEW CRACKS AND GROWTH RATE OF EXISTING CR ACKS INSPECTION OF <100% OF WELDS AFTER Si JUSTIFIABLE FOR  :

SMALL DIAMETER PIPING j INSPECTION PLAN ADEQUATE TO DETERMINE IF MAJOR IGSCC PROBLEM EXISTS AT OYSTER CREEK l

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g MEETING

SUMMARY

DISTRIBUTION

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iDocketFiIel  ?'

NRC PDR PDI4 Gray File S. Varga B.Boger J. Stolz A.Drorrerick OGC E. Jordan B. Grirres ACRS (10)

GPA/PA HBClayton NRC Participants A.Dromerick W.H. Koo

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