ML20238F667
| ML20238F667 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 08/28/1998 |
| From: | Gore P, Langdon J, Yemma L CAROLINA POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML20238F663 | List: |
| References | |
| PROC-980828, NUDOCS 9809040179 | |
| Download: ML20238F667 (8) | |
Text
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A ENCLOSURE BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-324/ LICENSE NO. DPR-62 REINSPECTION PLAN 1
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l CORE SHROUD INSPECTION PLAN UNIT 2 B214R1 OUTAGE APRIL 1999 i
9909040179 990828 i PDR ADOCK 05000324 l- G PDR I
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. . Core Shroud Inspection Plan Unit 2 B214R1 Outage April 1999 1
i Prepared by:
Phil Gore John Langdon Larry Yemma August 18,1998 Recommended by: e Date: T//f/'77 i
Approved by:
iy 6 - -/ MM Date: P/4/[ff 7
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Core Shroud Inspection Plan Brunswick Steam Electric Plant, Unit No 2 Refueling Outage 13 (B214RI), April 1999
SUMMARY
OF B214R1 INSPECTION PLANS The scope ofinspections for the Brunswick Steam Electric Plant (BSEP), Unit No. 2 Refueling Outage 13 (i.e., .B214RI) core shroud includes baseline inspections as well as reinspection.
Several factors were used to determine the scope: results of previous inspections performed on both BSEP units, results within the industry, and follow-up actions and commitments from previous inspections. Guidance on shroud inspection and flaw evaluation contained in the Boiling Water Reactor Vessel and Internals Program (BWRVIP) documents BWRVIP-01, " Core Shroud Inspection and Flaw Evaluation Guideline, Revision 2," and BWRVIP-07, " Guidelines for Reinspection of BWR Core Shrouds," were also used. The NRC Safety Evaluation on BWRVIP-07 was also used in determining the reinspection frequency of the core shroud welds.
A discussion of the inspection plans for each weld or component is provided in detail herein, and includes inspection history, results, and analytical conclusions.
Weld H1 will be re-inspected in 100 percent of the accessible areas using ultrasonic examinations (i.e., UT). Since the shroud head bolt lugs limit access of the inspection tooling to less than 20 percent of the upper side of the weld, Carolina Power & Light (CP&L) Company is having the inspection tooling modified to permit increased coverage of this weld. It is expected that the new technique will allow increasing the inspection coverage of this weld to over 75 percent. The inspection technique will be qualified in accordance with BWRVIP guidelines.
Welds H2 and H3 were structurally replaced with twelve clamps during the Refueling Outage 10 (i.e., B211RI), so these welds no longer require inspection. Five of the clamps will be visually inspected, which will complete the baseline inspection of the twelve clamps installed.
Weld H4 will be reinspected in 100 percent of the accessible area using UT.
Weld H5 will not be inspected. Analysis of the Refueling Outage 12 (i.e., B213R1) UT results concluded that the weld has sufficient structural margin to operate until Refueling Outage 15 (i.e., B216RI) before reinspection is necessary.
Welds H6A and H7 will not be inspected. Analysis of the B212R1 UT results concluded that these welds have sufficient structural margin to operate until Refueling Outage 14 (i.e., B215RI) before reinspection is necessary.
Weld H6B will be reinspected in 100 percent of the accessible area using UT.
No inspections are planned for weld H8 orshroud support leg welds since inspection tooQ: .nd techniques have not been fully developed that will work on the BSEP type shroud.
e Since no flaws were found on weld H9 during the UT inspections performed in the B211R1 outage, no inspections are planned.
INSPECTION HISTORY and PLANS FOR B214RI For discussion purposes, coverage addresses the total amount of the welds' circumference that was inspected by the specified inspection technique (i.e., if 78 percent of the weld was inspected, this means 78 percent of the circumference was inspected). The amount of cracking discussed is in reference to the amount of the inspected area that was found to be cracked (i.e., of the 78 percent inspected,15 percent was cracked).
Weld Hi In the B211R1 outage,11.1 percent of the outside surface was visually (i.e., VT) inspected with no cracking found.
In the B212RI outage, the baseline inspection was completed using UT on 100 percent of the accessible areas. This weld presents unique challenges to UT inspection since the shroud head
. hold down bolt lugs prevent access to most of the upper side of the weld. UT was performed on 24 uniformly distributed locations representing 23.1 percent of the weld. A total of 3.6 percent cracking was found, with crack depths ranging from 0.22 to 0.27 inches. All of the cracking was located on the outer ring surface side of the weld. On the lower side of the weld,83.3 percent was UT inspected with 38.5 percent cracked. The crack depths were from 0.06 to 0.53 inches.
The guide rod brackets and mre spray piping prevented access to the remaining areas of the weld. Analysis of the UT., .nhowene weld had sufficient structural margin to operate until the B214R1 outage before reinspection was necessary.
Welds H2. H3. and the Structural Clamps Welds H2 and H3 were structurally replaced with twelve clamps during the B211R1 outage; therefore, no inspection of these welds is required. Four of the clamps were VT inspected during j the B212R1 outage, and three were inspected in the B213R1 outage. No indications were noted in either inspection. The five remaining clamps will be VT inspected during the B214R1 outage, thereby completing the baseline inspection of the twelve clamps.
Weld H4 In the B211R1 outage, the baseline inspection was completed using UT on 100 percent of the accessible areas. A total of 78 percent was inspected with 26.1 percent cracked. Jet pumps, guide rod brackets, and core spray piping prevented inspection of the remaining areas.
Although analysis showed the weld to have sufficient structural margin to operate until the j B214R1 outage before reinspection would be necessary, CP&L elected to monitor selected areas of the cracking for growth. Select areas were reinspected during the B212RI and B213R1
. outages, with no measurable growth noted.
Weld H5 In the B211R1 outage,100' percent of the accessible areas of the weld were inspected. Attempts were made to UT this weld, but the inspection tooling would not pass by thejet pump riser brace l arms. A total of 4.6 percent of the weld was inspected using UT, with no cracking found.
' CP&L finished the inspections using VT. On the inside surface,92.8 percent of the area was f-inspected with 11.3 percent cracked. On the outside surfaces, over 30.6 percent was inspected with 6.4 percent cracked.
l In the B213R1 outage, the baseline inspection was completed using UT on 100 percent of the 1 l accessible areas. The tooling had been modified for the installed clamps and the clearance issues from the jet pump riser brace arms. A total of 83.6 percent of the lower side of the weld was
- inspected with no cracking. On the upper side of the weld, the riser brace arms again prevented access of the transducer packages to all but 34.9 percent of the weld with no cracking found. The guide rod brackets, core spray piping, andjet pumps also prevented access to areas on both sides of the weld. Analysis showed the weld has sufficient structural margin to operate until the l B216R1 outage before reinspection is necessary.
!- Weld H6A L ~ In the B211R1 outage, over 11 percent of the outside surfaces were VT inspected with no circumferential cracking noted. Inaccessibility prevented inspections on the inside surfaces.
In the B212RI outage, the baseline inspection was completed using UT on 100 percent of the accessible areas. A total of 79 percent of the weld was inspected with 5.3 percent cracked. The cracking was located exclusively on the ring side of the weld, with crack depths ranging from 0.08 to 0.27 inches. Analysis showed the weld has sufficient structural margin to operate until the B215R1 outage before reinspection is necessary.
Weld H6B
. In the B211R1 outage, over 11 percent of the outside surfaces were VT inspected with one, l.5 circumferential crack noted. Inaccessibility prevented inspections on the inside surfaces.
-In the B212R1 outage, UT was performed on 100 percent of the accessible areas of the weld.
78.4 percent was inspected with 69.3 percent cracked. The cracking initiated exclusively from
' the inner plate-side heat affected zone of the weld, with crack depths ranging from 0.10 to 0.79 inches.
In the B213R1 outage, UT was used to re-inspect 100 percent of the accessible areas. Using
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L . modified tooling, CP&L increased the' coverage to 84.3 percent with 73 percent found cracked.
- No significant growth was noted in the previously inspected areas. The crack depths ranged from
0.05 to 0.75 inches. Jet pumps, guide rod brackets, and core spray down comers prevented inspection of additional areas. Analysis showed the weld had sufficient structural margin to operate until the B214R1 outage before reinspection is necessary.
Weld H7 In the Bi lD outage, over 11 percent of the outside surfaces were VT inspected with no circur nerentia. cracks noted. Inaccessibility prevented inspections of the inside surfaces.
In the B212R1 outage, the baseline inspection was completed using UT on 100 percent of the accessible areas. A total of 75.6 percent was inspected with 10.9 percent cracked. The cracking initiated exclusively from the 304 stainless steel side of the weld on the inner surface. The uack depths were from 0.06 to 0.52 inches. Analysis showed the weld had sufficient structural margin to operate until the B215R1 outage before reinspection is necessary.
Weld H8 No previous inspections have been performed, or are planned during the B214R1 outage, for this weld. This weld presents significant accessibility challenges since access to the upper side of the weld is very restricted due to the jet pump diffusers, core spray piping, and guide rod brackets.
CP&L estimates that less than 40 percent of the weld is accessible for UT from the annulus area due to the clearance between the jet pump diffusers and the shroud support plate (i.e., less than 2 inches) and the openings for thejet pump diffusers in thejet pump baffla olate.
Access to the weld from beneath the baffle plate is even more restrictive due to the openings in thejet pump baffle plate for thejet pump diffusers and the core shroud support legs. Total coverage is estimated to be less than 30 percent of the weld from this side of the weld. The most coverage for this weld can be obtained from the fuel side of the shroud support; however, a l
- considerable number of fuel cells will require vacating to gain access. I No inspection techniques or tooling have been completely developed and tested that will inspect in excess of 50 percent of this weld. While some inspection tooling is available in the industry, it ;
, will not provide complete coverage of all areas ofinterest on the weld, nor will it cover at least 50 percent of the weld circumference. When inspection. tooling and techniques are available and tested that will provide at least the minimum required inspections, CP&L plans to inspect this f weld consistent with BWRVIP guidance. i Weld H9 ;
During the B212R1 outage, the baseline inspection was completed using UT on 100 percent of the accessible areas. Over 99 percent of the weld was inspected with no cracking noted. Based )
on the current BWRVIP-38 guidelines, reinspection is not necessary until the B217R1 outage. l 1
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Core Shroud Support Lees There currently are no inspection equipment, techniques, or approved BWRVIP inspection and evaluation guidelines available for inspecting the core shroud support legs. When these become available, CP&L will inspect these areas consistent with BWRVIP guidance.
Vertical Welds VI and V2 (located between welds 111 and H2)
These welds were visually inspected on the outside diameter surfaces in 1991 with no indications found. Since these welds are outside the beltline region as defined by the current BWRVIP-07 guidelines, no inspections are planned.
Vertical Welds V3 and V4 (located between welds H3 and H4)
These welds were VT inspected during the B210R1 outage on the inside and outside surfaces with no indications noted. These welds will be baseline inspected using UT on 100 percent of the accessible areas during the B214R1 outage.
Vertical Welds V5 and V6 (located between welds H4 and H5)
Weld V5 was VT inspected during the B210R1 outage on the inside and outside surfaces with no indications noted. Weld V6 was VT inspected during the B210R1 outage on the outside surface only with no indications noted. These welds will be baseline inspected using UT on 100 percent of the accessible areas during the B214R1 outage.
Vertical Welds V7 and V8 (located between welds H5 and H6)
These welds were VT inspected during the B210R1 outage on the outside surface with no indications noted. Since the cracking on welds H5 and H6A is less than the current BWRVIP guidelines, no inspections are planned during the B214RI outage.
Vertical Welds V9. V10 and Vil (located between welds H6B and H7)
These welds were VT inspected during the B210R1 outage on the outside surfaces with no indications noted. Since these welds are outside the beltline region, as defined by the current BWRVIP-07 guidelines, no inspections are planned.
Rine Segment Welds HIl rine. H2/H3 rine, and H6A/H6B rine)
Welds H1, H6A, and H6B are not repaired; therefore, no inspections are required by the current BWRVIP-07 guidelines. The clamps installed on the H2/H3 welds replace the H2/H3 ring segment welds; therefore, no inspections are necessary.
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.. .. j INSPECTION SCOPE EXPANSION.
' Scope expansions will be performed dependent on inspection results on a component-by-component basis in accordance with BWRVIP guidance.
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