ML20212F526
| ML20212F526 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 09/22/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20212F509 | List: |
| References | |
| NUDOCS 9909280234 | |
| Download: ML20212F526 (14) | |
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g 1 UNITED STATES
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e NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20066 4 001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ON THE SECOND 10-YEAR INTERVAL INSERVICE INSPECTION PROGRAM REQUESTS FOR RELIEF NOS. 1-98-001 AND 1-98-002 ARKANSAS NUCLEAR ONE. UNIT 1 DOCKET NO. 50-313
1.0 INTRODUCTION
The Technical Specifications for Arkansas Nuclear One, Unit 1 (ANO-1), state that the inservice inspection (ISI) 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 (the Code) and applicable addenda as required by Section 50.55a(g) of Title 10 of the Code of Federa/ Regulations (10 CFR), 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.
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 regulations require that inservice examination of components and system pressure tests 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 rt:ference in 10 CFR 50.55a(b),12 months prior to the start of the 120-month interval, subject to the ! imitations and modifications listed therein. The Code of record for ANO-1, second 10-year ISI intervalis the 1980 Edition through Winter 1981 Addenda of Section XI of the ASME Code.
Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance with an examination requirement of Section Xi of the ASME Code is not practical for its facility, information shall be submitted to the Commission in support of that determination and a request made for relief from the ASME Code requirement. After evaluation of the determination, pursuant to 10 CFR 50.55a(g)(6)(i), the Commission may grant relief and may impose alternative requirements that are determined to be authorized by law, will not endanger life, property, or the common defense and security, and are otherwise in the public interest, giving Enclosure 9909290234 990922 PDR ADOCK 05000313 P PDR
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. due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.
By letter dated June 1,1998, Entergy Operations, Inc. (the licensee), submitted to the NRC its Second 10 Year Interval ISI Program Plan Requests for Relief Nos. 1-98 001 and 1-98-002, for ANO-1. The licensee has determined that the Code requirements discussed in the relief requests were impractical. The staff has reviewed and evaluated the licensee's requests for relief pursuant to 10 CFR 50.55a(g)(6)(i).
2.0 EVALUATION The staff, with technical assistance from its contractor, the Idaho National Engineering and Environmental Laboratory (INEEL), has evaluated the information provided by the licensee.
Based on the results of the review, the staff adopts the contractor's conclusions and ,
recommendations presented in the attached Technical Letter Report (TLR). The basis for disposition of each relief request is documented below.
Reauest for Relief 198-001 ASME Code,Section XI, IWB 2412 and IWC-2412 specify the minimum and maximum percent of examinations that are required to be completed and credited each period. For the first period, the examination percentage distribution will be between 16 and 34 percent. The second period examination percentage distribution will be between 50 and 67 percent, and the third period distribution w!ii be 100 percent.
Pursuant to 10 CFR 50.55a. the licensee requested relief from the Code-required periodic examination percentages as listed in the attached table in INEEL's TLR, Section 2.1.
During preparation of the 1R13 Owner's Activity Report for the third period of ANO-1's second interval, the licensee discovered that the periodic examination percentage requirements had not been met for a number of examination categories.- The failures to meet the period distribution requirements ranged from not meeting the minimum examination percentage requirements (two examination categories received 0 percent first period examination maximum examination percentage requirements for thecond firstinspection and se,s) to exceeding periods. the However, the licensee did meet the third period percentage requirements.
The second 10-year interval ended June 1,1997, so it is impossible for the licensee to meet the second 10-year interval, first and second periodic percentage requirements. Considering that the licensee has completed the third period 100 percent examination requirements, and that no flaws or conditions were found that required analytical evaluation or repair / replacement, reasonable assurance of structuralintegrity of the components has been provided.
The staff determined that it is impractical (impossible) for the licensee to satisfy the second 10-year interval, first and second periodic percentage requirements. The licensee has completed the third period 100 percent examination requirements, and no flaws or conditions were found that required analytical evaluation, repair, or replacement. The staff concludes that the third period examinations provide reasonable assurance of structuralintegrity of the subject components. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i). The relief is authorized by law, will not endanger life, property, or the common defense and security, and is i.
otherwise in the public interest, giving due consideration to tha burden upon the licensee that could result if the requirements were imposed on the facility.
Reauest for Relief 1-98-002 (Part 1)
ASME Code,Section XI, Examination Category B-G-1, item B6.40 requires 100 percent volumetric examination of the threads in the reactor pressure vessel (RPV) flange as defined by Figure IWB-2500-12.
Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee requested relief for RPV flange threads 01-F-001 through 01-F-060. >
The staff determined that component geometry, including alignment pins and a seal surface on l the reactor vessel flange, limits access and precludes complete volumetric examination of the threaded portions of the flange.
To complete the Code-required volumetric examination, design modifications of the RPV would be necessary. Therefore, the staff concluded that the Code required volumetric examination of the flange threads is impractical. The licensee's examination of a significant portion (80 !
. percent) of the Code-ren" ired volume of the RPV flange threads provides reasonable assurance that the strMwO integrity has been provided for the subject components. !
Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i). The relief is authorized by law, ;
will not endanger life, 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. !
Reauest for Relie; '-98-002 (Part 2) !
1 ASME Code,Section XI, Examination Category B-D, item B3.130 requires 100 percent volumetric examination of Class 1 steam generator nozzle-to-vessel welds as defined by '
Figure IWB 2500-7.
Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee requested relief for steam generator nozzle-to-head welds04-006 and 04-008.
- The staff % ermined that the examinations are limited by physical restrictions; specifically, the skirt fixtures around the nozzles. The skirt fixtures make 100 percent volumetric examination impractical for these areas. To gain access for examination, the steam generator would require design modifications. Therefore, the staff concluded that the Code-required volumetric examination is impractical. The licensee's examination of the subject welds to the extent practical, i.e., obtaining 70 percent examination coverage for each nozzle, provides reasonable assurance of structuralintegrity of the subject components. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i). The relief is authorized by law, will not endanger life, 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.
I l
4 Reauest for Relief 1-98-002 (Part 31 1
ASME Code,Section XI, Examination Category B-H, item B8.40 requires 100 percent !
volumetric or surface examination, as applicable, as defined by Figures IWB-2500-13, -14, and l -15, for heat exchanger integrally welded attachments.
l Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee requested relief from the Code-required !
100 percent surface examination of heat exchanger integrally welded attachment 37-006. The licensee examined 66 percent of the subject weld.
The staff determined that complete examination is r~estricted by physical obstructions that make the 100 percent surface examination impractical. To gain access for examination, modification l of the component or surrounding structure would be required. The licensee's examination of l
the subject integral attachments to the extent practical, i.e., obtaining a significant portion (66 percent) of the required area, provides reasonable assurance of structuralintegrity of the subject component. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i). The relief is authorized by law, will not endanger life, property, or the common defense and security, and l is otherwise in the public interest, giving due consideration to the burden upon the licensee that
- i. could result if the requirements were imposed on the facility.
3.0 CONCLUSION
The staff concludes that for Requests for Relief Nos. 1-98-001, and 1-98-002, Parts 1,2, and 3, the Code requirements are impractical at ANO 1. Since the examinations described in Request for Relief No.1-98 001 were not performed during the time period required by the Code, the I l staff concluded that it is impractical, at this time, to meet the requirement for the second '
l interval. The components described in Request for Relief No.1-98-002 would require design
! modifications to comply with the Code requirements, which would impose a significant burden l
upon the licensee. The staff concluded that the examinations performed by the licensee provide reasonable assurarice of structuralintegrity of the subject components. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i) for Requests for Relief Nos.1-98-001 and 1-98-002 for the second 10-year ISI interval at ANO-1. The relief is authorized by law, will not endanger life, 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.
Attachment:
Technical Letter Report Principal Contributor: T. McLellan Date: September 22, 1999 L
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l TECHNICAL LETTER REPORT ON SECOND 10-YEAR INTERVAL INSERVICE INSPECTION '
REQUESTS FOR RELIEF 1-98 001 AND 1-98-002 FOR ENTERGY OPERATIONS. INC.
I ARKANSAS NUCLEAR ONE - UNIT 1 DOCKET NUMBER: 50-313 1
1
1.0 INTRODUCTION
i By letter dated June 1,1998, the licensee, Entergy Operations, Inc., submitted Requests for .
1 Relief 198-001 and 1-98-002 seeking relief from the requirements of the ASME Code,Section XI, for the Arkansas Nuclear One - Unit 1. These relief requests are for the second 10-year inservice inspection (ISI) interval. The Idaho National Engineering and Environmental Laboratory (INEEL) staff's evaluation of the subject requests for relief is in the following section.
2.0 EVALUATION
- The information provided by Entergy Operations, Inc., in support of the requests for relief from Code requirements has been evaluated and the bases for disposition are documented below.
The Code of record for the Arkansas Nuclear One - Unit 1 second 10-year ISI interval, which ended June 1,1997,is the 1980 Edition through winter 1981 Addenda of Section XI of the ASME Boiler and Pressure Vessel Code.
2.1 Reauest for Relief No. 198-001. lWB-2412. and IWC-2412. Inspection Proaram B l Percentaae Reauirements l Code Reauirement: IWB-2412 and IWC 2412 specify the minimum / maximum percent of examinations that are required to be completed / credited each period. For the first period, the examination percentage distribution will be between 16% and 34%. The second i
ATTACHMENT l
period examination percentage distribution will be between 50% and 67%, and the third period distribution will be 100% I i
1.icensee's Code Relief Reauest: In accordance with 10 CFR 50.55a, the licensee l 1
requested relief from the Code required periodic examination percentages as listed in the '
following table:
l 1 Period 1R7,1R8.1M89 2'* Period 1R9.1R10 3* Period 1R11,1R12.1R13 Range Required: 16-34% Range Required: 50-67% 100% Required !
Cum. Cum.
Total Total Cum. Total Total q Exams Total Exams Total Exams cum. Total Exams I required Exams credited Exams credited Cum. Exams credited Cum.%
Exam for performed
)
for %* for Performed for %*for performed for for Cat. Interval for Penod Period Period for interval Interval Interval for Interval Interval Interval B-B 9 4 4 ! 9 9 9 11 100.00 B-F 39 16 16 -
28 28 39 39 100.00 B-G-2 19 5 5 26.32 9 9 19 19 100.00 l BH 11 0 0 1 1 11 11 100.00 B-J 108 80 36 33.33 198 72' 66.67 254 108 100.00 !
- i BK1 5 4 4 4 4 5 5 100.00 C-A 8 2 2 25.00 6 6 8 8 100.00 j C-B 7 0 0 2
5 4 57.14 9 7 100.00 C-C 39 6 6 .
27 27 39 39 100.00 ,
CF 115 19 19 16.52 76 76 66.09 148 115 100.00 I D-B 66 38 38 54 54 80 66 100.00 FA 122 276 41 33.61 586 81 66.39 740 122 100.00
- Areas highlighted represent percentages of non-compliance.
Licensee's Basis for Reauestina Relief (as stated):
The Code of Federal Regulations 10CFR50.55(a)(g) and Arkansas Nuclear One Unit 1 (ANO-1), Technical Specification 4.0.5 require that ASME Code Class 1,2, and 3 systems be routinely inspected as an assurance of continued structuralintegrity of system pressure boundaries. These regular inspections are to be performed per Section XI of the ASME Boiler and Pressure Vessel Code.
During the preparation of the 1R13 Owner's Activity Report (OAR 1) for the third period of ANO-1's 2"8 interval as required by ASME Code Case N-532
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I- l and 10CFR50.55a, it was discovered that the inspection period distribution l requirements had not been met for certain ASME Section XI Code Examination Categories. The attached table provides an overview of the examinations completed for each Examination Category during the 2"8 ten-l year inservice inspection interval and where the ASME Code period percentage requirements have not been met. The jnterval percentage requirements have been met for the 2"' Ten-year Inservice Inspection Interval, i.e.,100.
Period distribution requirement alterations range from failing to meet the minimum to exceeding the maximum examination distribution percentage requirements for inspection periods 1 and 2. Period 3 met the 100%
interval percentage requirements. Examinations are required to be distributed somewhat uniformly over the course of a ten-year inspection interval to ensure that degradation which may be occurring over the plant
! life does not go undetected for an extended period of time. Examinations were performed in the 3* inspection period for each of the affected examination categories. These examinations serve as sufficient proof of the continued integrity of the affected components. Consequently, failure to satisfy the period distribution requirements for these examination categories l during the 1st and 2nd periods did not pose a safety concern since the inspections performed during the 3"' period did not reveal any flaws or relevant conditions requiring analytical evaluation or repair / replacement for continued service.
The first ten-year interval started on December 19,1974, and ended on January 5,197, in accordance with ASME Section XI. During this first ten-year interval ,w ANO-1, the Code of Record initially used was the 1971 Edition. On April 19,1978, ANO-1 updated to the 1974 Edition, Summer 1975 Addenda (74/S75). The 74/S75 Code was used from that date until 4 the end of the first 10 year Interval on January 5,1985. For the second interval, ANO-1 updated to the 80/W81 code. An "as-building" of the ANO-1 inservice inspection program was started in mid 1990, and investigations revealed that the selection criteria for components to tfe inspected used from the beginning of the 2nd interval until mid 1990 was the 74/S75 Code, not the 80/W81 Code. The "as-building" was completed (during the first half of 1993) with the thought that all the discrepancies in the selection criteria
, had been identified. It was not until the OAR-1 preparation for the third period inspections that it was discovered additional discrepancies in the ANO 1 inservice inspection program had not been addressed. These discrepancies are listed in the attached table.
Since the interval percentage requirements have been met for the 2nd i ten-year inservice inspection interval, i.e.,100%, and the continued integrity of the components for the affected categories were verified by the 3rd period inspections, Entergy Operations believes that the alterations have not affected the safe operation of ANO-1.
r - '- ~ -
Licensee's Prooosed Alternative Examination (as stated):
None Evaluation: IWB 2412 and IWC-2412 specify the minimum / maximum percent of examinations that may be completed / credited each period. For the first period, the examination percentage distribution will be between 16% and 34%. The second period examination percentage distribution will be between 50% and 67%, and the third period distribution will be 100%. During preparation of the 1R13 Owner's Activity Report (OAR-
- 1) for the third period of ANO-1's 2"d interval, the licensee discovered that the periodic examination percentage requirements had not been met for a number of examination categories. The failures to meet the period distribution requirements ranged from not meeting the minimum examination percentage requirements (two examination categories received 0% first period examinations) to exceeding the maximum examination percentage requirements for inspection periods 1 and 2. However the licensee did meet the third period percentage requirements.
The second 10-year interval ended June 1,1997, so it is impossible for the licensee to meet the second 10-year interval, first and second periodic percentage requirements.
Considering that the licensee has completed the third period 100% examination requirements, and that no flaws or conditions were found that required analytical evaluation or repair / replacement, reasonable assurance of structuralintegrity of the components has been provided.
Therefore, based on the reasonable assurance of the structuralintegrity of the subject components, and the impracticality (impossibility) of complying with the Code periodic percentage requirements for first and second periods of the second 10-year interval, the INEEL staff recommends that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).
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5-l 2.2 Reauest for Relief No. 1-98-002 (Part 1 1. Examination Cateaory B-G-1. Item B6.40.
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Pressure Retainina Boltina. Greater Than 2 inch in Diameter Qode Reauirement: Examination Category B-G-1, item B6.40 requires,100% volumetric examination _of the threads in the reactor pressure vessel flange as defined by Figure !
l'NB-2500-12.
Licensee's Code Relief Reauest: In accordance with 10 CFR 50.55a(g)(5)(iii), the licensee requested relief for the following reactor pressure vessel flange threads:
' COVERAGE COMPONENT ID ACHIEVED 01-F-001 through 80 %
01-F-060 l Licensee's Basic for Reauestina Relief (as stated): )
l The Code of Federal Regulations 10CFR50.55(a)(g) and Arkansas Nuclear One, Unit 1 (ANO-1), Technical Specifications 4.0.5, require that ASME Code Class 1,2, and 3 systems be routinely inspected as an assurance of continued structuralintegrity of system pressure boundaries. These regular inspections must be performed per Section XI of the ASME Boiler and Pressure Vessel Code.
During 2*' interval, sixty components received examinations that were less ;
than 100% examination volume as required by ASME Section XI 80/W81... ,
.The incomplete examinations resulted from limited acdessibility due to geometric limitations in the design. The attached examination reports describe the interference which limited each components' examination.
Obstructions located on or adjacent to these components produce an area in which the ultrasonic transducer may not be maneuvered to obtain full coverage of the components. For inservice inspection (ISI) exam numbers 01-F-001 through 01-F-060, the coverage was 80%, which does not me(e)t the ASME Section XI 80/81 requirement and to which Code Case N-460
. does not apply.... Modification of the affected components to permit complete examinations would create a significant burden on Entergy Operations.
4-Il '. For ease of evaluation the INEEL staff divided Request for Relief 198 002 in-to Parts 1. 2, and 3.
l l
6-Entergy Operations has examined the reactor vessel flange threads ... to the maximum extent possible using the technologies that are commercially available. Examination of the accessible weld volumes is sufficient to-
, provide reasonable assurance of structuralintegrity, since past examinations of accessible welds have revealed no service-induced flaws.
It is therefore, reasonable to conclude that the same results would be.
obtained for the inaccessible portions of the welds, if it were practical to
! inspect them.
The limited examinations revealed no service-induced flaws in any of the inspected portions of the components. The probability of a significant flaw existing in any of the remaining portions of these components is unlikely.
Licensee's Proposed Alternative Examination (as stated):
None l Evaluation: The Code requires 100% volumetric examination of the threads in the RPV flange. NDE reports (including figures) supplied by the licensee show that component geometry, including alignment pins and a seal surface on the reactor vessel flange, limits access and precludes complete volumetric examination of the threaded portions of the flange.
To complete the Code-required volumetric exemination, design rnodifications of the RPV would be necessary. Therefore, the Code required volumetric examination of the flange threads is impractical. Imposition of the requirement would create a significant burden on the licensee.
s The licensee has examined a significant portion (80%) of the Code-required volume of the RPV flange threads. Based on the significant amount of coverage obtained, it is reasonable to conclude that any patterns of degradation, if present, would have been detected. Therefore, reasonable assurance of the structuralintegrity has been provided.
Based on the impracticality of meeting the Code's volumetric examination requirements for the subject components, and the reasonable assurance of structural integrity provided by the' examinations that have been performed, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).
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7 g 2.3 Beauest for Rglief No. 1-98 002 (Part 2L Examination Cateaorv B-D. Item B3.130. Steam i Generator Nozzle-to-Vessel Welds l
i Code Reauirement: Examination Category B-D, item B3.130 requires 100% volumetric examination of Class'1 steam generator nozzle-to-vessel welds, as defined by Figure IWB-2500-7.-
! Licensee's Code Relief Reauest: In accordance with 10 CFR 50.55a(g)(5)(iii), the licensee requested relief for the following steam generator nozzle-to-head welds:
COVERAGE COMPONENT ID ACHIEVED 04-006 70%
04-008 70 %
Licensee's Basis for Reauestina Relief (as stated):
The Code of Federal Regulations 10CFR50.55(a)(g) and Arkansas Nuclear One, Unit 1 (ANO-1), Technical Specifications 4.0.5, require that ASME Code Class 1,2, and 3 systems be routinely inspected as an assurance of continued structuralintegrity of system pressure boundaries. These regular inspections must be performed per Section XI of the ASME Boiler and Pressure Vessel Code.
During 2" interval, ... components received examinations that were less than the 90% examination volume as required by Code Case N 460. The incomplete examinations resulted from limited accessi,bility due to geometric limitations in the design. The attached examination reports describe the interference which limited each components' examination.
Obstructions located on or adjacent to these components produce an area in which the ultrasonic transducer may not be maneuvered to obtain full coverage of the components. ....For ISI exam numbers04-006 and 04-008, j the coverage was limited to 70%, ... Modification of the affected l
components to permit complete examinations would create a significant burden on Entergy Operations.
- Entergy Operations has examined the ... Class 1 welds to the maximum extent possible using the technologies that are commercially available.
Examination of the accessible weld volumes is sufficient to provide reasonable assurance of structuralintegrity, since past examinations of accessible welds have revealed no service induced flaws. It is therefore,:
b i-l l
, o reasonable to conclude that the same results would be obtained for the inaccessible portions of the welds, if it were practical to inspect them.
The limited examinations revealed no service-induced flaws in any of the inspected portions of the components. The probability of a significant flaw existing in any of the remaining portions of these components is unlikely.
Licensee's Prooosed Alternative Examination (as stated):
None Evaluation: The Code requires 100% volumetric examination of the subject nozzle-to- I vessel welds. NDE reports (including figures) supplied by the licensee show that the exami' nations are limited by physical restrictions, the skirt fixtures around the nozzles.
The skirt fixtures make 100% volumetric examination impractical for these areas. To gain access for examination, the steam generator would require design modifications.
Imposition of this requirement would create a significant burden on the licensee.
The licensee has examined the subject welds to the extent practical, obtaining 70%
examination coverage for each nozzle. Based on the examinations completed, it is reasonable to conclude that patterns of degradation, if present, would have been detected. Therefore, reasonable assurance of structuralintegrity has been provided.
Based on the impracticality of meeting the Code examination requirements for the subject nozzle-to-vessel welds, and the reasonable assurance provided by the examinations that were completed, it is recommended that relief be granted pu[suant to 10 CFR 50.5Sa(g)(6)(i).
2.4 Reauest for Relief No. 198-002 (Par 13). Examination Cateaorv B-H. Heat Exchancer intearal Attachment Welds' Code Reauirement: Examination Category B-H, item B8.40 requires 100% volumetric or surface examination, as applicable, as defined by Figures IWB-250013, -14, 15, for heat exchanger integrally welded attachments.
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9 Licensee's Code Relief Reauest: In accordance with 10 CFR 50.55a(g)(5)(iii), the licensee requested relief from the Code-required 100% surface examination of heat exchanger integrally welded attachment 37-006. The licensee examined 66%
examination of the subject weld.
I Licensee's Basis for Reauestino Relief (as stated):
The Code of Federal Regulations 10CFR50.55(a)(g) and Arkansas Nuclear One, Unit 1 (ANO-1), Technical Specifications 4.0.5, require that ASME l Code Class 1,2, and 3 systems be routinely inspected as an assurance of continued structuralintegrity of system pressure boundaries. These regular inspections must be performed per Section XI of the ASME Boiler and Pressure Vessel Code.
During 2"d interval, . . components received examinations that were less than the 90% examination volume as required by Code Case N-460. The incomplete examinations resulted from limited accessibility due to geometric limitations in the design. The attached examination reports describe the interference which limited each components' examination.
Obstructions located on or adjacent to these components produce an area l in which the ultrasonic transducer may not be maneuvered to obtain full coverage of the components. ....for ISI exam numbers37-006 the coverage was limited to 66%, ... Modification of the affected components to permit complete examinations would create a significant burden on Entergy Operations.
Entergy Operations has examined the ... Class 1 welds to the maximum extent possible using the technologies that are commercially available.
Examination of the accessible weld volumes is sufficiept to provide reasonable assurance of structural integrity, since past examinations of accessible welds have revealed no service-induced flaws. It is therefore, reasonable to conclude that the same results would be obtained for the inaccessible portions of the welds, if it were practical to inspect them.
The limited examinations revealed no service induced flaws in any of the inspected portions of the components. The probability of a significant flaw existing in any of the remaining portions of these components is unlikely.
Licensee's Proposed Alternative Examination (as stated):
None
p .,
1 j Evaluation: The Code requires 100% surface examination of the subject heat exchanger l
integral attachment weld. The liquid penetrant examination report (including sketch) supplied by the licensee confirm that complete examination is restricted by physical obstructions that make the 100% surface examination impractical. To gain access for examination, modification of theIomponent or surrounding structure would be required.
Imposition of this requirement would create an undue burden on the licensee.
The licensee has examined the subject integral attachments to the extent practical, obtaining a significant portion (66%) of the required area. Based on the significant amount of coverage obtained,it is reasonable to conclude that any patterns of degradation, if present, would have been detected. Therefore, reasonable assurance of structural integrity has been provided.
Based on the impractical;ty of meeting the Code examination requirements for the subject integral attachment, and the reasonable assurance provided by the examination that was completed, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).
3.0 CONCLUSION
The INEEL staff has reviewed the licensee's submittal and concludes that for Requests for Relief Nos. 1-98-001, and 1-98-002, Parts 1,2, and 3, the Code requirements are impractical at Arkansas Nuclear One - Unit 1 and that reasonable assurance of structural integrity is provided by the examinations performed. Therefore, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).
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