ML20210D895

Safety Evaluation Accepting First 10-yr Interval Inservice Insp Plan Requests for Relief ISI-018 - ISI-020

ML20210D895
Person / Time
Site:	Waterford
Issue date:	07/23/1999
From:	NRC (Affiliation Not Assigned)
To:
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ML20210D875	List: ML20210D870 ML20210D895
References
NUDOCS 9907280060
Download: ML20210D895 (11)

Text

f p5 880 ye t UNITED STATES

, , j j NUCLEAR REGULATORY COMMISSION g WASHINGTON, D.C. 2055!KXX)1 I

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION i

FIRST 10-YEAR INTERVAL INSERVICE INSPECTION PLAN REQUESTS FOR RELIEF NOS. ISI-018 THROUGH ISI-020 EO_B ENTERGY OPERATIONS. INC.

WATERFORD STEAM ELECTRIC STATION. UNIT 3 DOCKET NO. 50-382

1.0 INTRODUCTION

Inservice inspection of the American Society of Mechanical Engineers (ASME) Code Class 1,2, and 3 components shall be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code and applicable addenda as required by Title 10 of the Code of Federal Reaulations, Section 50.55a(g) (10 CFR 50.55a(g)), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). Section 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

l Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1,2, and 3 components (including  ;

supports) shall meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, " Rules for Inservice Inspection of Nuclear Power Plant Components," to the extent practical within the limitations of design, geometry, and materials of construction of the components. The l regulations require that inservice examination of components and system pressure tests l conducted during the first 10-year interval and subsequent intervals comply with the >

requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by

reference in 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. For Waterford Steam Electric Station, Unit 3 l (Waterford 3), the applicable edition of Section XI of the ASME Code for the first 10-year inservice inspection (ISI) interval is the 1980 Edition through Winter 1981 Addenda.

! By letter dated June 30,1998, Entergy Operations, Inc. (the licensee), submitted Requests for Relief ISI-018 through IS!-020, seeking relief from the requirements of the ASME Code,Section XI, for the first 10-year ISI interval for Waterford 3.

9907280060 990723 Enclosure PDR ADOCK 05000382 P PDR

2-2.0 EVALUATION The Idaho National Engineering and Environmental Labore. tory's (INEEL's) evaluation of the subject Requests for Relief Nos. ISI-018 through ISI-020 is attached. Based on the results of its review, the NRC staff adopts the contractor's conclusions and recommendations presented in the Technical Letter Report (TLR).

The information provided by the licensee in support of the requests for relief from Code requirements has been evaluated and the basis for disposition is documented herein.

Reauest for Relief 1S1-018:

Examination Category B-A, Item B1.10, Alternative to 10 CFR 50.55a(g)(6)(ii)(A), Augmented Reactor Pressure Vessel Examination Pursuant to 10 CFR 50.55a(g)(6)(ii)(A), all licensees must implement once, as part of the ISI intervalin effect on September 8,1992, an augmented examination of the reactor pressure vessel (RPV) shell welds specified in item B1.10 of Ext.mination Category B-A of the 1989 Edition of the ASME Code,Section XI. Examination Category B-A, items B1.11 and B1.12 require volumetric examination of essentially 100 percent of the RPV circumferential and longitudinal shell welds, as defined by Figures IWB-2500-1 and -2, respectively. Essentially 100 percent, as defined by 10 CFR 50.55a(g)(6)(ii)(A)(2), is greater than 90 percent of the examination volume of each weld, provided the reduction in coverage is due to part geometry or interference by another component. As an alternative to the regulations, the licensee proposed that the examinations performed satisfy the augmented reactor vessel examination requirement.

Pursuant to 10 CFR 50.55a(g)(6)(ii)(A)(5), the licensee proposed to use the actual RPV examinations performed as an alternative to the " essentially 100%" requirement in the regulations. The examination coverages obtained are listed in the TLR.

At Waterford 3, the augmented coverage requiremerits cannot be met for selected RPV shell welds due to physical restrictions that limit scan coverage. Adjacent radial support and flow skirt support lugs that are welded to the RPV interna' surface limit coverage to 62 percent of the required examination volume for Weld 01-008. For Welds01-009,01-012, and 01-013, examinations are limited to 67,85, and 74 percent, respectively, by the location of specimen tube holders. l l

Licensees must make a reasonable effort to maximize examination coverage of their reactor vessels. In cases where examination coverace from the inside surface is inadequate, examination from the outside surface (OD) using manual inspection techniques may be an option. However, at Waterford 3, the close proximity to the biological shield and geometrical obstructions limit access from the OD. Therefore, the licensee cannot enhance coverage significantly by examining from the OD.

The staff determined that the licensee examined a significant portion of the subject welds, and has met the coverage requirements for the remaining welds. The cumulative volumetric examination coverage for all of the RPV shell welds was 90.17 percent. The staff concludes that, based on the volumetric examination coverage attained, any significant patterns of

3-degradation, if present, will be detected and that the examinations performed provide reasonable assurance of the continued structuralintegrity of the subject RPV shell welds.

Therefore, the licensee's proposed alternative provides an acceptable level of quality and safety and is authorized pursuant to 10 CFR 50.55a(g)(6)(ii)(A)(5).

Reauest for Relief No. ISI-019:

ASME Code,Section XI, Examination Category B-A, item B1.10 requires 100 percent volumetric examination of the Class 1 reactor vessel circumferential and longitudinal shell welds as defined by Figuros IWB-2500-1 and -2.

Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee requested relief from the Code-required I 100 percent volumetric examination of the RPV shell welds01-008,01-009,01-012, and 01-013.

The Code requires that reactor pressure vessel shell welds be 100 percent volumetrically examined during the inspection interval. At Waterford 3, the Code coverage requirements cannot be met for the subject RPV shell welds due to physical restrictions that limit scan j coverage. Adjacent radial support and flow skirt support lugs that are welded to the RPV '

internal surface limit coverage to 62 percent of the required examination volume for Weld 01-008. For Welds01-009,01012, and 01-013, examinations are limited to 67,85, and 74 percent, respectively, by the location of specimen tube holders. The staff determined that the examinations are impractical to perform for the subject RPV shell welds. To perform the Code examinations design modifications would be required to allow access from the inside surface and would impose a burden on the licensee, i

The licensee has examined the RPV shell welds to the maximum extent practical. The staff determined that based on the significant portion of the volumetric examination completed I (90 percent cumulative), a pattern of degradation,if present, would have been detected. The examinations performed provide reasonable assurance of the continued structuralintegrity of the subject welds. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i).

Reauest for Relief No.1S1-020:

ASME Code,Section XI, Examination Category B-A, Item B1.30 requires 100 percent volumetric examination of the Class 1 reactor vessel circumferential shell-to-flange weld as defined by Figure IWB-2500-4.

Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee requested relief from examining 100 percent of the Code-required volume of RPV circumferential Upper Shell-to Flange Weld 01-020. Due to the surface taper, only 79 percent of the weld could be examined.

The licensee noted, that due to the geometric configuration of the shell-to-flange weld (surface taper of the flange), the examination coverage was limited to 79 percent for RPV circumferential Upper Shell-to-Flange Weld 01-020. The staff determined that it is impractical to examine the j subject welds to the extent required by the Code. For complete examination coverage,

redesign and modification of the reactor vessel would be necessary. Imposition of this requirement would cause a considerable burden on the licensee.

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! The licensee has performed the volumetric examination to the maximum extent practical on the subject weld and a significant portion of the volumetric examinations were completed.

Therefore, the staff determined that weld examined coverage provides reasonable assurance of continued structuralintegrity of the subject weld. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i).

3.0 CONCLUSION

For Requests for Relief ISI-019 and ISI-020, imposition of the requirements in strict compliance with the Code is impractical. Examinations performed provide reasonable assurance of the structural integrity. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i). The relief granted is authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.

For Request for Relief ISI-018, the licensee has made a reasonable effort to maximize examination coverage of the shell welds for the augmented RPV examination. The examinations performed provide an acceptable level of quality and safety. Therefore, the licensee's proposed alternative is authorized purcuant to 10 CFR 50.55a(g)(6)(ii)(A)(5).

Attachment:

Technical Letter Report Principal Contributor: T. McLellan Date: July 23, 1999 l

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• l TECHNICAL LETTER REPORT ON FIRST 10-YEAR INTERVAL INSERVICE INSPECTION REQUESTS FOR RELIEF ISI-018 THROUGH 1S1-020 i FOR ENTERGY OPERATIONS. INC.

WATERFORD 3 STEAM ELECTRIC STATION .

DOCKET NUMBER: 50-382 1

1. INTRODUCTION By letter dated June 30,1998, the licensee, Entergy Operations, Inc., submitted Requests for Relief ISI 018 through ISI 020, seeking relief from the requirements of the ASME Code,Section XI, for the Waterford 3 Steam Electric Station first 10-year inservice inspection (ISI) interval. The Idaho National Engineering and Environmental Laboratory (INEEL) staff's evaluation of the subject requests for relief are in the following section.

2. EVALUATION The information provided by Entergy Operations, Inc. in support of these requests for j relief from Code requirements and the proposed altemative to Augmented Reactor )

Vessel Examinations has been evaluated and the bases for disposition are documented below. The Code of record for the Waterford 3, first 10-year ISI interval, which ended June 30,1997,is the 1980 Edition through Winter 1981 Addenda of Section XI of the .

ASME Boiler and Pressure Vessel Code. l l

A. Reauest for Relief ISI-018. Examination Cateaorv B-A. Item B1.10. Alternative to 10 CFR 50.55a(a)(6)(ii)(A). Auamented Reactor Pressure Vessel Examination Reaulatorv Reauirement: In accordance with 10 CFR 50.55a(g)(6)(ii)(A), all licensees must implement once, as part of the inservice inspection interval in effect on l September 8,1992, an augmented examination of the reactor pressure vessel (RPV) shell welds specified in item B1.10 of Examination Category B-A of the 1989 Edition of 1 the ASME Code,Section XI. Examination Category B-A, items B1.11 and B1.12 require volumetric examination of essentially 100% of the RPV circumferential and longitudinal ,

shell welds, as defined by Figures IWB-2500-1 and -2, respectively. Essent: ally 100%, as l defined by 10 CFR 50.55a(g)(6)(ii)(A)(2), is greater than 90% of the examination volume of each weld, previded the reduction in coverage is due to part geometry or interference by another component.

Licensee's Prooosed Alternative: Pursuant to 10 CFR 50.55a(g)(6)(ii)(A)(5), the licensee proposed to use the actual RPV examinations performed as an alternative to the

" essentially 100%" requirement in the regulations. The examination coverages obtained are listed in the following table.

Attachment

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Item Exam Weld ID Component Description No. Coverage Stated Limitation 01-008 RPV Bottom Head assembly B1.11 62 % Exam limited due to the radial to lower shell circumferential support and flow skirt support weld lugs.01-009 RPV lower shell course B1.12 67 % Exam limited due to proximity longitudinal weld at 90* of specimen tube holders.

l 01-010 RPV tower shell course B1.12 100 %

l longitudinal weld at 210' 01 011 RPV lower shell course B1.12 100 %

longitudinal weld at 330' 01 012 RPV lower shell to middle 81.11 85% Exam limited due to specimen shell circumferential weld tube holders.01-013 RPV middle shell courst B1.12 74 % Exam limited due to proximity longitudinal weld at 90' of specimen tube holders.01-014 RPV middle shell course B1.12 100 %

longitudinal weld at 210' 01 015 RPV middle shell course B1.12 100 %

longitudinal weld at 330'01-016 RPV middle shell to upper B1.11 100 %

shell circumferential weld 01-017 RPV upper snell course B1.12 100 %

longitudinal weld at 90'01-018 RPV upper shell course B1.12 100 %

longitudinal weld at 210'

.01-019 RPV upper shell course B1.12 100%

l l longitudinal weld at 330*

The licensee stated:

"Waterford 3 completed the required reactor vessel shell weld examinations to the  !

extent practical using the following techniques:

"1. Vessel circumferential, longitudinal welas were ultrasonically examined using a O degree search unit to identify any laminar areas or flaws in the specific volume.

"2. The 45 and 60 degree scans were also employed in four directions (clockwise, counterclockwise, up and down) for the purpose of detecting any planar or nonlaminar flaws,.

"3. The inner 25% of the vessel wall was examined in four directions using a 50/70 bi-modal transducer for the purpose of detecting any 'near surface' or

' underclad' flaws.

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l l "4. The 50/70 scans were also used to provide examination coverage in the area l where the 45 and 60 degree scans were ineffective due to 'near-zone' limitations."

Licensee's Basis for Proposed Attemative (as stated):

" Examination from the outside diameter (OD) surface is not possible for the affected areas of 01-009,01-012, and 01-013 due to the close proximity of the concrete biological shield. Examination from the OD could possibly allow Waterford 3 to meet the ' essentially 100%' requirement for 01-008. However, geometrical obstructions which prevented full coverage from the inside diameter may interfere with an OD examination. In addition, full compliance with the augmented requirements of 10 CFR 50.55a from the OD surface of the RPV would result in significant personnel time and exposure.

"The cumulative total volume of the Waterford 3 RPV shell welds was 90.17%.

Furthermore, the only indication was determined to be a small laminar reflector in 01-009, which was acceptable without analytical evaluation. Therefore, it is unlikely that the unexamined sections would not be acceptable for continued service.

Although this cumulative total cannot be used to meet the RPV augmented requirements, this percentage supports the fact that the invessel examination covered a significant volume and provides an acceptable level of quality and safety.

"Therefore, pursuant to 10 CFR 50.55a(g)(6)(ii)(A)(5), EOl requests NRC approval of the examination as an alternative to ' essentially 100%' exam based on the acceptable level of quality and safety."

Evaluation: To comply with the augmented RPV examination requirements of 10 CFR 50.55a(g)(6)(ii)(A), licensees must volumetrically examine essentially 100% of each of the item B1.10 shell welds. Essentially 100% is defined as greater than EO% of the examination volume of each weld, where the reduction in coverage is due to interference by another component or to part geometry. As an alternative to the regulations, the licensee proposed that the examinations performed satisfy the augmented reactor vessel examination requirement.

At Waterford 3, the augmented coverage requirements cannot be met for selected RPV  ;

shell welds due to physical restrictions that limit scan coverage. Adjacent radial support and flow skirt support lugs that are welded to the RPV internal surface limit coverage to 62% of the required examination volume for Weld 01-008. For Welds01-009,01-012, and 01-013, examinations are limited to 67%,85%, and 74%, respectively, by the location of specimen tube holders.

As a result of the augmented volumetric examination nile, licensees must make a reasonable effort to maximize examination coverage of their reactor vessels. In cases where examination coverage from the ID is inadequate, examination from the outside surface (OD) using manualinspection techniques may be an option. However, at Waterford 3, the close proximity to the biological shield and geometrical obstructions limit access from the OD. Therefore, the licensee cannot enhance coverage significantly by examining from the OD.

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1 The licensee has examined a significant portion of the subject welds, and has met the i coverage requirements for the remaining welds. The cumulative volumetric examination  !

t coverage for all of the RPV shell welds was 90.17%. Based on the volumetric I l

examination coverage attained, the INEEL staff concludes that any significant patterns of I degradation, if present, would have been detected and that the examinations performed provide reasonable assurance of the continued structuralintegrity of the subject RPV shell welds. Therefore, it is concluded that the proposed alternative provides an acceptable level of quality and safety and it is recommended that the licensee's proposed alternative be authorized pursuant to 10 CFR 50.55a(g)(6)(ii)(A)(5).

B. Reauest for Relief No.1S1-019 Examination Cateoorv B-A. Item B1.10. Pressure Retainina Reactor Vessel Shell Welds Code Reauirement: Examination Category B-A, item B1.10 requires 100% volumetric examination of the Class 1 reactor vessel circumferential and longitudinal shell welds as defined by Figures IWB-2500-1 and -2.

Licensee's Code Relief Reauest: In accordance with 10 CFR 50.55a(g)(5)(iii), the licensee requested relief from the Code-required 100% volumetric examination of the following RPV shell welds:

Item Exam Weld ID Component Description No. Coverage Stated Limitation 01 008 RPV Bottom Head assembly B1.11 62 % Exam limited due to the radial to lower shell circumferential support and flow skirt support weld lugs.

e 01009 RPV lower shell course B1.12 67 % Exam limited due to proximity of longitudinal weld at 90* specimen tube holders.01-012 RPV lower shell to middle B1.11 85% Exam limited due to specimen shell circumferential weld tube holders.01-013 RPV middle shell course B1.12 74 % Exam limited due to proximity of longitudinal weld at 90' specimen tube holders.

Licensee's Basis for Reauestina Relief (as stated):

" Code Case N-460 allows a reduction in examination coverage on any Class 1 weld provided the reduction in coverage for that weld is less than 10%. EO! determined that four of the twelve item Number B1.10 welds could not be examined essentially 100% However, the total weld volume coverage for all Item B1.10 welds exceeds 90 % (90.17). These examinations were performed from the inside diameter using a O degree search unit to identify any laminar areas of flaws in the specified volume, together with 45 and 60 degree scans employed in four directions (clockwise, counterclockwise, up and down) for the purpose of detecting any planar or nontaminar flaws. Additionally, the inner 25% of the vessel wall was examined in

f four directions using a 50/70 bi-modal transducer for the purpose of detecting any

'near surface' or ' underclad' flaws and the 50/70 scans were also used to provide examination coverage in the area where the 45 and 60 degree scans were ineffective due to 'near-zone' limitations.

" Examination from the outside diameter (OD) surface is not pocsible for the affected areas of 01-009,01-012, and 01-013 due to the close proximity of the concrete biological shield. Examination from the OD could possibly allow Waterford 3 to meet the ' essentially 100%' requiremerit for 01-008. However, geometrical obstructions which prevented full coverage from the inside diameter may interfere with an OD examination. In addition, full compliance with the augmented requirements of 10 CFR 50.55a from the OD surface of the RPV would result in signitant personnel time and exposure.

"The cumulative total volume of the Waterford 3 RPV shell welds was 90.17%.

Furthermore, the only indication was determined to be a small laminar reflector in 01-009, which was acceptable without analytical evaluation. Therefore, it is unlikely that the unexamined sections would not be acceptable for continued service.

Although this cumulative total cannot be used to meet the Code requirements, this percentage supports the fact that the invessel examination covered a significant volume and provides an acceptable level of quality and safety."

Licensee's Proposed Alternative Examination (as stated):

"Waterford 3 completed the required reactor vessel shell weld examinations to the extent practical using the following techniques:

"1. Vessel circumferential, longitudinal welds were ultrasonically examined using a O degree search unit to identify any laminar areas or flaws in the specific volume.

"2. The 45 and 60 degree scans were also employed in four directions (clockwise, counterclockwise, up and down) for the purpose of detecting any planar or nonlaminar flaws.

"3. The inner 25% of the vessel wall was examined in four directions using a 50/70 bi-modal transducer for the purpose of detecting any 'near surface' or

' underclad' flaws.

"4. The 50/70 scans were also used to provide examination coverage in the area where the 45 and 60 degree scans were ineNetive due to 'near zone' limitations."

Evaluation: The Code requires that reactor pressure vessel shell welds be 100%

volumetrically examined during the inspection interval. At Waterford 3, the Code coverage requirements cannot be met for the subject RPV shell welds due to physical restrictions that limit scan coverage. Adjacent radial support and flow skirt support lugs that are welded to the RPV internal surface limit coverage to 62% of the required examination volume for Weld 01-008. For Welds01-009,01-012, and 01-013, l

\

6-examinations are limited to 67%,85%, and 74%, respectively, by the location of specimen tube holders. These examinations are therefore impractical to perform for the subject RPV shell welds. To increase the examination coverage, design modifications would be required to allow access from the inside surface (ID). Therefore, imposition of this requirement would result in a considerable burden on the licensee.

The licensee has examined the RPV shell welds to the maximum extent practical. Based

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on the significant portion of the volumetric examination completed (90% cumulative), it is )

reatonable to conclude that a pattern of degradation , if present, would have been detected. As a result, reasonable assurance of the continued structuralintegrity of this weld has been provided. Therefore, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i). 3 J

C. Reauest for Relief No.1S1-020. Examination Cateaorv B-A. Item B1.30. Pressure Retainina Welds in the Reactor Vessel Code Reauirement: Examination Category B-A, item B1.30 requires 100% volumetric examination of the Class 1 reactor vessel circumferential shell to-flange weld as defined by Figure IWB-2500-4.

Licensee's Code Relief Reauest: In accordance with 10 CFR 50.55a(g)(5)(iii), the licensee requested relief from examining 100% of the Code-required volume of RPV circumferential Upper Shell-to Flange Weld 01-020. Due to the surface taper, only 79%

of the weld could be examined.

Licensee's Basis for Reauestino Relief (as stated):

"The design configuration of the flange precludes full ultrasonic examination of the RPV Upper Shell-to-Flange Weld,01-020. The weld volume was examined from the vessel wall and the flange face using 5 different transducers. However due to the taper of the flange the transverse scans were limited in Volume 'A' to 48% and Volumes 'B', 'C', and 'D' to 54%, limiting total examination coverage to 79%. In I order to examine the weld in accordance with the Code requirement, the reactor vessel would require extensive design mocifications. Consequently, the design restriction makes the Code-required examination impractical. Waterford believes that the significant coverage obtained would have detected any generic degradation, if present, and therefore provides reasonable assurance of structural integrity."

Licensee's Proposed Alternative Examination (as stated):

1 "Waterford 3 performed a best-effort ultrasonic examination to achieve as much code coverage as possible."

Evaluation: The Code requires that the subject reactor pressure vessel shell-to-flange weld be 100% volumetrically examined during the inspection interval. Due to the geometric configuration of the shell-to-flange weld (surface taper of the flange), the examination coverage was limited to 79%. Based on the information provided in this request for relief, it is impractical to examine the subject welds to the extent required by l

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7 the Code. For complete examination coverage, redesign and modification of the reactor vessel would be necessary. Imposition of this requirement would cause a considerable burden on the licensee.

The licensee has performed the volumetric examination to the maximum extent practical on the subject weld. Based on the significant portion of the volumetric examinations completed, it is reasonable to conclude that a pattern of degradation, if present, would have been detected. As a result, reasonable assurance of continued structuralintegrity l has been provided. Therefore, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).

3.0 CONCLUSION

The INEEL staff evaluated the licensee's submittal and concluded that certain inservice examinations cannot be performed to the extent required by the Code at Waterford 3.

For Requests for Relief ISI-019 and ISl-020, imposition of the requirements in strict compliance with the Code is impractical. Examinations performed provide reasonable assurance of the structuralintegrity,' therefore, it is recommended that relief be granted as requested pursuant to 10 CFR 50.55a(g)(6)(i).

For Request for Relief ISI-018, the licensee has made a reasonable effort to maximize examination coverage of the shell welds for the augmented RPV examination. The examinations performed provide an acceptable level of quality and safety, therefore, it is i recommended that relief be authorized pursuant to 10 CFR 50.55a(g)(6)(ii)(A)(5). l l

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