ML20198P484
| ML20198P484 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 10/08/1997 |
| From: | Gore P, Langdon J, Wilton B CAROLINA POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML20198P479 | List: |
| References | |
| PROC-971103, NUDOCS 9711070183 | |
| Download: ML20198P484 (8) | |
Text
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1 Brunswick Steam Electric Plant, !
Unit No. 2 Core Shroud Inspection Plan ;
Revision 1 1 Outage B213R1 Prepared by:
Phil Gore John Langdon Blane Wilton October 8,1997 Recommended by it( ve/fL Date:ii/0/f/9 7 f ;-
Approved by:
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- ' BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO. 2 CORE SIIROUD INSPECTION PLAN REVISION 1 OUTAGE B213R1
SUMMARY
OF INSPECTIONS The scope of core shroud reinspections for the Brunswick Steam Electric Plant (BSEP), Unit
- No. 2 is based on several factors. Results of previous inspections performed on both BSEP, Unit No. I and BSEP, Unit No. 2, as well as results within the industry, are key inputs into the inspection plan. Follow-up actions and commitments established from the last inspection are also included in the determination of the inspection scope. Guidance on shroud inspections and flaw evaluation, contained in the Boiling Water Re ictor Vessel Internals Program (BWPVIP) documents BWRVIP-01, " Core Shroud Inspection and Evaluation Guidelines," and BWRVIP-07, " Core Shroud Reinspection Guidelines," is also used.
Based on the previous inspection results, inspections of welds 111, ll6A,117 and H9 are not planned. Since welds 112 and 113 have been structurally replaced with clamps, these welds no longer require inspection, llowever, three of the twelve repair clamps for welds 112/113 will be visually inspected. The B211R1 ultrasonic testing (UT) inspection results for weld 114 demonstrated that the weld does not require re inspection until the B214R1 outage.1lowever, based on CP&L's internal program to monitor growth rates on core shroud welds, two 20 inch long areas vi weld 114 will be inspected, using UT, during B213Rl. Weld 115 will be re-inspected, using UT, since the B211R1 inspection was performed using only visual testing (VT) methods on both the inside and outside weld surfaces. Weld Il6B will be re-inspected using UT for changes in the crack lengths and/or depths. No inspections of weld 118 or the shroud support legs are planned since the BWRVIP has not completed development of the inspection and evaluation guidelines, and inspection tooling and techniques, that will work on the BSEP type shroud, have not been fully developed.
UNIT 2 CORE SilROUD REINSPECTION PLAN Weld ii1 was inspected using VT at four (4) locations (i.e.,1 I percent of the ciremnference) on the outside surface, during the B211R1 outage, with no indications noted. During the B212R1 outage,100 percent of the accessible area was inspected using UT from the outside surface. This included 30.9 percent of the upper weld surface area, of which 2.7 percent of the weld length examined had circumferential cracking. The upper weld surface has significant UT tool access limitations due to the shroud head bolt lugs, the guide rod brackets, and the core spray piping.
The lower weld surface area was inspected on 83.3 percent of the surface area, with 32.1 percent of the inspected weld length having circumferential cracking. The lower weld surface area UT Page 2 i
tool access is limited due to the location of the guide rod brackets and the core spray piping.
Analysis of the weld showed that no inspection was necessary during the B213R1 outage.
Welds 112 and 113 were structurally replaced with twelve clamps during the B211R1 outage.
Therefore, no inspection of these wc!ds is required. Although BWRVIP-07 only requires inspection of 25 percent of the repair clamps cach outage, CP&L inspected four (4) of the clamps using VT techniques during the B212R1 outage, with no indications noted. Th ce (3) additional clamps will be inspected using VT during this outage, bringing the total repair clamps that will have been inspected to seven (7).
Weld 114 was inspected using UT in 100 percent of the accessible areas during the B211R1
- outage, obtaining coverage of 78.8 percent of the total weld with circumferential cracking found in 26.1 percent of the areas inspected. The guide rod brackets, core spray piping, and jet pump riser brace arms prevented access to some areas of the weld. Although analysis showed the weld was qualified to operate for 1800 days (i.e., until the B214R1 outage), CP&L elected to monitor the circumferential crack growth rates at two locations with UT during the B212R1 outage. No growth outside the UT technique uncertainty factors was detected. CP&L plans to use UT to inspect these same two areas for circumferential crack length and depth growth during the B213R1 outage.
An attempt to inspect the 115 weld using UT was made during the B211R1 outage, but was aborted due to significant access limitations from thejet pumps and associated components for the UT tool. The UT inspections were replaced with VT inspections, where 100 percent of the inside weld surfaces and 30.6 percent of the outside weld surfaces were inspected.
Circumferential cracking was found on 13.6 percent of the inside weld surfaces and 6.8 percent of the outside weld surfaces. The close proximity of thejet pumps to the core shroud outside surfaces prevented 100 percent inspection of the outside surfaces using VT. Since analysis showed the weld was structurally sound to operate for 1400 days (i.e., until the B213R1 outage),
no irapections were performed during the B212R1 outage. CP&L plans to use UT to inspect the 115 weld during the B213R1 outage to gain additional coverage and determine the depth of the cracking. The coverage for this weld is projected to be greater than 70 percent, with the guide rod brackets, core spmy piping, m.d jet pump riser brace arms preventing access to some areas.
Weld ll6A was inspected on 6 percent of the outside surface during the B211 R1 outage using VT, with one,1.5 inch long circumferential crack found. During the B212R1 outage, this weld was inspected in 100 percent of the accessib!c areas using UT, which resulted in 79 percent of the total weld being inspected. Circumferential cracking was found in 5.3 percent of the inspected area. Analysis determined the weld does not require re-inspection during B213R1 Weld 116B was inspected on 6 percent of the outside weld surface during the B211R1 outage I using VT, with no circumferential cracking found. During the B212R1 outage, this weld was i l inspected in 100 percent of the accessible areas using UT, which resulted in 78.4 percent of the total weld being inspected. Circumferential cracking was found in 69.6 percent of the inspected area. Analysis determined the weld required re-inspection during B213RI. For the B213R1 UT ;
inspection, the Electric Power Research Institute Non-Destructive Examination Center was !
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i contracted to develop a phased array UT techniqu:. The technique will enable CP&L to obtain mere refmed data on the lengths and depths of the circumferential cracking in this weld, it is expected that at least the same coverage will be obtained as was obtained during the B212R1 outage.
Weld 117 was inspected on 6 percent of the outside weld surface during the B211R1 outage using VT, with no circumferential cracking found. During the B212R1 outage, this weld was inspected in 100 percent of the accessible areas using UT, which resulted in 75.6 percent of the total weld being inspected. Circumferential cracking was found in 10.9 percent of the inspected area. Analysis determined the weld does not need to be re-inspected until the B215RI outage, so no inspections are planned for the B213R1 outage.
No inspections have been performed, or are planned during the B213R1 outage, for the 118 weld.
This weld presents significant accessibility challenges since the upper side of the weld is very restricted due to the jet pump diffusers, core spray piping, and guide rod brackets. The lower side of this weld has even more restrictive access due to thejet pump baffle plate and the need to disassemble fuel cells for access from the bottom head region. Additionally, the BWRVIP has not completed development of the inspection and evaluation guidelines, nor have inspection techniques :md tooling been completely developed. While some inepection tooling is available, it will not work at BShP due to the clamps installed around the 112 and 113 welds. When the BWRVIP completes th:se guidelines, and inspection tooling and techniques are available, CP&L plans to inspect this webt consistent with BWRVIP guidance.
Although not currently required in the BWRVIP guidelines, CP&L inspected the H9 weld during the B212RI outage. Since the 119 weld is directly attached to the reactor pressure vessel (RPV) shell to bottom head weld, CP&L qualified a UT technique to inspect the 119 weld in conjunction with the RPV shell-to-bottom head weld. The inspection coverage was 99 percent of the weld, with no indications noted. Since no indications were noted during the B212R1 inspections, no inspections are planned for the B213R1 outage.
The BWRVIP has not completed inspection and evaluation guidelines for the shroud support legs and other areas below the core plate. Additionally, equipment and techniques have not been developed for these areas. When these guidelines and inspection tooling and techniques are available, these areas will be inspected consistent with BWRVIP guidance.
A summary of the inspection history and plans for each weld, r.nd for the clamps, is 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. The UT uncertainty has been detennined in qualification testing by the inspection vendor, and meets the BWRVIP guidelines.
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j If any unusual findin'gs are wnfirmed upon inspection of the three clamps, the remaining clamps l
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will be inspected. j EVALUATION i J- 1 t
An engir.eering evaluation of the inspection results will be performed using the flaw evaluation i
guidance of the BWRVIP-01 and BWRVIP-07 documents. No significant changes from the last ;
,' inspection results are expected.
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TABLEI ,
Unit 2 Refueling Outage 12 (B213RI) Core Shroud Reinspection .
I RCPSPECTION
. WELD LASTINSPECTION RESULTS METIIOD' ' B213R1 INSPECTION PLANS AND COMMENTS j HI Outage B212Rl - UT of 100 percent of the None planned Analysis concluded that no mspections were needed accessible inside diameter and outside diameter this outage. Sufficient structural margins exist, and any :
areas. anticipated growth of indications will not impact .
st uctural margins. ;
H2 NA N/A Replaced by clamps during the B211R1 outage. ;
113 NA ' N/A Replaced by clamps during the B211R1 outage. ,
'114 Outage B212R1 - UT at two 20 inch areas for UT UT inspection of the same two 20 inch areas is planned i i
crack depth growth determination. No growth this outage as part of a BSEP internal program to outside the correction factors for the UT monitor crack growth. The next inspection, per :
technique was detected. BWRVIP Guidelines,is scheduled for the B214RI outage. !
115 Outage B212R1 - None performed. UT Analysis ofinspections following the B211R1 outage concluded that no inspections were required until this i
- o itage. Plan to inspect 100 percent of accessible areas which is projected to be in excess of 70 percent of the .
total weld.
II6A Outage B212RI - UT 100 percent of accessible None plamied Analysis concluded that no inspections were required areas which resulted in 79 percent of the total this outage.
weld being inspected. Found circumferential cracking in 53 percent ofexamined weld length.
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TABLE 1 Unit 2 Refueling Outage 12 (B213RI) Core Shroud Reinspection REINSPECTION WELD LAST INSPECTION RESULTS METIIOD* B213RI INSPECTION PLANS AND COMMENTS II6B Outage B212RI - UT 100 percent of accessible UT Analysis concluded that inspection was required this areas which resulted in 78.4 percent of weld outage. Plan to inspect 100 percent of accessible areas length being inspected. Circumferential cracking with phased array UT technique to refine cracking was found in 69.6 percent ofinspected weld lengths and depths. Total weld coverage is expected to length. be at least that obtained during the B212RI outage.
117 Outage B212R1 - UT 100 percent of accessible None planne Analysis of the B212RI outage data concluded that no areas resulting in 75.6 percent of the total weld inspections were required this ou: age. Suflicient length being examined. Circumferential cracking structural margin exists and any anticipated growth of was found in 10.9 percent ofinspected weld indications will not impact structural margins.
length.
118 None None planned Awaiting BWRVIP development of inspection tools / techniques.
119 Outage B212RI - UT 100 percent of accessible None planned Not scheduled for inspection this outage. Sur. kient areas. 99 percent of weld length examined with structural ma. gin exists. Any anticipated grows 9f no flaws noted. indications will not impact structural margins.
Shroud Not inspected. None planned BWRVIP developing inspection tools / techniques.
support legs Page 2
. a TABLE 1 .
Unit 2 Refueling Outage 12 (B213RI) Core Shroud Reinspection REINSPECTION WELD IASTINSPECTION RESULTS METHOD
- B213R1 INSPECTION PLANS AND COMMENTS Shroud Outage B212RI - VT of 4 different installed VT Inspect 3 clamps for general . pre rain e, missing parts.
clamps clamps. and integrity of tack welds. Will bring the total clamps '
inspected to 7 of the 12 total installed.
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- Non-destructive examire. ion methads to be qualified in accordance with "BWRVIP Reactor Pressure Vessel and Internals Examination
- Guidelines" issued by the DWRVIP. t t
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