ML20148L761

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Core Shroud Insp Plan Unit 2 B213R1 Outage,Sept 1997
ML20148L761
Person / Time
Site: Brunswick Duke Energy icon.png
Issue date: 06/12/1997
From: Gore P, Langdon J, Wilton B
CAROLINA POWER & LIGHT CO.
To:
Shared Package
ML20148L760 List:
References
PROC-970612, NUDOCS 9706190371
Download: ML20148L761 (7)


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Core Shroud Inspection Plan Unit 2 B213R1 Outage SEPTEMBER,1997 Prepared by:

Phil Gore John Langdon Blane Wilton June 12,1997 Recommended by:

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l Core Shroud Inspection Plan Brunswick Steam Electric Plant, Unit No 2 B213R1 Outage September,1997

SUMMARY

OF PREVIOUS INSPECTIONS The scope of reinspection for the Brunswick Steam Electric Plant (BSEP), Unit No. 2 Core Shroud is based on the results of previous inspections performed on both BSEP Unit No. I and Unit No. 2, follow-up actions and commitments established from the last inspection and guidance on shroud inspections and flaw evaluation obtained in the " Core Shroud Inspection and Evaluation Guidelines", issued by the Boiling Water Reactor Vessel Internals Program (BWRVIP).

Inspection of the BSEP Unit No. 2 core shroud during the B211R1 refueling outage (May 1994) was prior to the issuance of Generic Letter 94-03. This inspection was also performed while development of some of the ultrasonic tooling currently being used was ongoing. Reliability problems arose and use of the tooling was abandoned. Automated ultrasonic testing (UT) scanners commonly used for shroud inspections will not work on the BSEP shrouds because of interference from the clamps on the H2 and H3 welds. Specialized tooling has since been developed to inspect the inside diameter (ID) and outside diameter (OD) surfaces of welds H1, H4,115, core support ring welds H6A and 116B and associated fillet welds, and weld H7. These welds were previously inspected from the OD only using VT. The H9 weld was previously inspected as part of the vessel beltline inspections because it is located directly behind one of the vessel beltline welds. Additionally, UT measurements were repeated at selected areas on the H4 during the B212R1 outage in order to assess crack growth during that cycle.

UNIT 2 CORE SHROUD REINSPECTION PLAN The reinspection plan for the core shroud focuses on the application ofimproved inspection techniques for welds where internal surfaces were not accessible, and on reinspecting are.as inspected last outage to determine crack growth rates. Tooling commonly used in the industry will not work on the BSEP shrouds due to interference from the H2/H3 repair clamps.

Specialized tooling has been developed to inspect these welds.

Welds H1, H2 and H3 will not be inspected this outage. One hundred percent (100%) of the accessible areas of the H1 weld were inspected during the B212R1 outage. Any anticipated growth of the noted indications will not impact structural margins. Welds H2 and H3 have been structurally replaced replaced by the clamps.

Weld H4 will be UT examined at two locations for determination of crack depth growth; these two locations were previously examined during the B212R1 refueling outage. The H5 weld was visually inspected on the ID and OD during the B211R1 refueling outage with relatively little Pao,e 2

U cracking noted. Carolina Power & Light Company plans to UT inspect the 115 weld during the B213R1 outage to gain additional coverage and determine the depth of the cracking.

Welds H6A, H7, and H9 will not be inspected this outage. One hundred percent (100%) of the accessible areas ofli6A, H7, and H9 were UT examined during the B212R1 outage. Any anticipated growth of the noted indications in welds H6A and H7 will not impact structural margins. No indications were noted in weld H9 during the B212R1 inspections.

Weld H6B will be re-examined this outage to determine crack growth and achieve additional coverage in areas not previously accessible. The phased array equipment utilizes smaller inspection probes which should permit access to additional areas of the weld. Additional, the phased array techniques are being designed to reduce the error band margins for depth and length.

Weld H8, the shroud support legs and other areas below the core plate will not be inspected this outage because the BWRVIP is still developing inspection and evaluation guidelines, and equipment and techniques have not been developed for these areas. These areas will be inspected in the future consistent with BWRVIP guidance.

Although not currently required in the BWRVIP guidelines, inspection of the H9 weld has already been performed. This weld is directly behind one of the vessel beltline welds, so examination of the H9 weld was performed as part of the beltline weld examination during the B212R1 refueling outage.

Three of the twelve repair clamps will be visually inspected in accordance with BWRVIP Inspection and Evaluation Guidelines to assure no degradation during the last cycle of operation.

Details of the scope ofinspection for each weld, and for the clamps, are described in Table 1.

During the course of the inspections, unanticipated interferences may be encountered that will require changes to this plan. These situations will be evaluated as they arise.

INSPECTION SCOPE EXPANSION Additional areas of the shroud welds will be inspected if crack growths are unusually higher than predicted crack growth and NDE measurement uncertainty. The NDE uncertainty will be determined in quali6 cation testing by the inspection vendor. These qualifications will be in accordance with the BWRVIP inspection guidelines.

If any unusual findings are confirmed upon inspection of the three clamps, the remaining clamps will be inspected to determine the extent of any changes.

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EVALUATION An engineering evaluation will be performed on the inspection results, using the flaw evaluation guidance of the BWRVIP " Core Shroud Inspection and Evaluation Guidelines." No significant changes from the last inspection results are expected.

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TABLE 1 ,

Unit 2 Refueling Outage 12 (B213RI) Core Shroud Reinspection i WELD PREVIOUS INSPECTION RESULTS REINSPECTION COMMENTS METIIOD*

111 1994 - VT of OD between 4 lug sets with no indications None planned Not scheduled for examination this outage. Sufikient structural  !

noted. margins exist. Any anticipated growth of indications will not impact i E '

1996 - UT of ~ M)% of the accessible ID and OD areas.

112 VT at 2 locatbns with circumferential cracking. N/A Replaced by clamps. l t

113 None N/A Same as 112.

114 1994 - UT of 100% of accessible area (78.8%) from OD. UT UT at 2 - 20" areas for crack depth growth determination.  ;

Found 110.6" of random ID circumferential cracking. No .

OD cracking found. Depths from 0.10" to 0.86".

1996 - UT at 2 - 20" areas for crack depth growth t determination. No significant growth detected. i 115 1994 - VT of 100% ofID and 30.5% of OD. 59.3" of UT Relatively little cracking found during 1994 (B211RI) outage circumferential cracking found on ID and 11" of inspections. Will UT this outage to obtain additional coverage. ,

circumferential cracking found on the OD -

1996 - None performed.

Il6A 1994 - VT 6% of OD with a 1.5" circumferential crack. None planned Not scheduled for examination this outage. Sufficient structural

.?.argins exist. Any anticipated growth of indications will not impact '

1996 - UT 100% of accessible areas. 79% of weld length structural margins.

examined with 5.3% of examined weld length flawed. ,

II6B 1994 - VT 6% of OD with no circumferential cracking. UT UT with phased array techniques to improve coverage and refine length and depth sizing capabilities..

1996 - UT 100% of accessible areas. 78.4% of weld length examined with 69.6% of examined weld length flawed.

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. o WELD PREVIOUS INSPECTION RESULTS REINSPECTION COMMENTS METHOD

  • 117 1994 - VT of 6% of the OD with no circumferential None planned Not scheduled for examination this outage. Sufficient structural cracking. margins exist. Any anticipated growth of indications will not impact 1996 - UT 100% of accessible areas. 75.6% of weld length examined with 10.9% of examined weld length flawed.

118 None None planned BWRVIP developing inspection tools / techniques.

119 1996 - UT 100% of accessible areas. 99% of weld length None planned Not scheduled for examination this outage. Sufficient structural examined with no flaws noted. margins exist. Any anticipated growth of indications will not impact structural margins.

r Shroud Not inspected. None planned BWRVIP developing inspection tools / techniques.

support legs Shroud 1994 -VT of 2 installed clamps. VT Inspect 3 clamps for general appearance, missing parts, and integrity clamps of tack welds. Will bring the total clamps inspected to 8 of the 12 1996 - VT of 3 different installed clamps. total installed.

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ENCLOSURE 2 )

l BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO. 2  :

NRC DOCKET NO. 50-324 OPERATING LICENSE NO. DPR-62 l SUBMITTAL OF UNIT 2 CORE SHROUD RE-INSPECTION PLANS  !

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LIST OF REGULATORY COMMITMENTS  !

l The following table identifies those actions committed to by Carolina Power & Light (CP&L) I Company in this document. Any other actions discussed in the submittal represent intended or l planned actions by CP&L. They are described to NRC for the NRC's information and are not l regulatory commitments. Please notify the Manager- Regulatory Affairs at the Brunswick l Steam Electric Plant of any questions regarding this document or any associated regulatory commitments.

Commitment Committed date or outage

1. Perform reinspections of the BSEP Unit No. 2 core shroud in B213R1 accordance with the Core Shroud Reinspection Plan dated June 12,  !

1997.

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2. Submit the results of BSEP Unit No. 2 core shroud re-inspections. Within 30 days following completion of the inspections.

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