ML20148H238
| ML20148H238 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 06/06/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20148H236 | List: |
| References | |
| NUDOCS 9706090295 | |
| Download: ML20148H238 (13) | |
Text
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g UNITED STATES g
j NUCLEAR REZULATORY COMMISSION WASHINGTON, D.C. 20066-0001 4
l SAFETY EVALUATION BY THE OFFICE OF NVCLEAR REACTOR REGULATION OF THE SECOND TEN YEAR INTERVAL INSERVICE INSPECTION PROGRAM PLAN !
RE0 VESTS FOR RELIEF f.QB._
NEBRASKA PUBLIC POWER DISTRICT COOPER NUCLEAR STATION i i
DOCKET NO. 50-298 '
l.0 INTRODUCTION I
The Technical Specifications (TS) for Cooper Nuclear Station (CNS) state that '
the 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 (B&PV) Code and applicable addenda as required by 10 CFR 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(1). The 10 CFR 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the Nuclear Regulatory Commission (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 difficulties 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 pre-service 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, l geometry, and materials of construction of the components. The regulations
! require that inservice examination of components and system pressure tests conducted during the first ten-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) twelve months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. The applicable edition of,Section XI of the ASME Code for the CNS second ten-year inservice inspection (ISI) interval is i
the 1980 Edition through Winter 1981 Addenda. The second 10-year interval end date was February 29, 1996.
4 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 ENCLOSURE 1 9706090295 970606 PDR ADOCK 05000298 G PDR
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Code requirement After evaluation of the determination, pursuant to i 10 CFR 50.55a(g)(6)(i), the Commission may grant relief rid may impose alternative requirements that are determined to be authorized by law, will not i
~ endanger life, property, or the common defense and security, and are otherwise i in the public interest, giving due consideration to the burdt:n upon the !
licensee that could. result if-the requirements were' imposed.
- In a letter dated June 20, 1996, Nebraska Public Power District (licensee), l submitted to the NRC its second ten-year inservice inspection interval program !
plan requests for relief for CNS. The licensee also provided additional :
- information in-its letter dated December 31, 1996. j 2.0 . EVALUATION The staff, with. technical assistance from its contractor, the Idaho National Engineering Laboratory (INEL), has evaluated the information provided by the ;
licensee-in support of its second ten-year inservice inspection interval . l program plan requests for relief for CNS. Based on the information submitted, i the staff adopts the contractor's conclusions and recommendations presented in the Technical Letter Report (TLR) enclosed. l The licensee provided information, as applicable, for changes incorporated by- ;
Amendment 4.1 to the Inservice Inspection Program Plan for the Cooper Nuclear i Station in its letters noted above. The staff has reviewed Amendment 4.1 to !
the Inservice Inspection Program. Amendment 4.1 consists of editorial changes, adjustments to the weld examination lists, and responses to NRC !
comments. The licensee in response to General Electric Service Information !
Letter No. 571, added augmented inservice inspections of instrument nozzle i safe-ends to the ISI program and proposed to perform supplemental volumetric -
- examinations of the~ entire instrument nozzle safe end for nozzles N10, N11A/B, i N12A/B, and N16A/B.. ,
In addition, the licensee submitted Revision 2 to Request for Relief RI-06 and !
four new requests, Requests for Relief RI-20, RI-21, RI-22, and RI-23. For '
Request for Relief RI-06 the original version of this relief request was granted in NRC Safety Evaluation dated January 27, 1986. The licensee ;
- requested relief from the Code-required 100% volumetric coverage of the bottom ;
head circumferential Weld HMC-BB-1 due to the proximity of the vessel skirt that limits scanning. Scanning is restricted, because of the close proximity of the support skirt to the weld, making it impractical to perform the examinations to the extent required by the Code.
For shell-to-flange circumferential Welds VCB-BC-5-1, -2, & -3, scanning is
. limited due to the flange configuration and the proximity of the vessel thermocouples. Therefore, it, is impractical for the licensee to perform the examinations to the extent required by the Code. To obtain 100% volumetric coverage for these welds, design modifications would be necessary. Imposition of this requirement would cause a considerable burden on the licensee. As an alternative the licensee proposed-to perform the volumetric examinations to the extent practical on the suoject welds. Based on the 86% volumetric
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coverage of the shell-to-flange welds and.74% volumetric coverage.of the bottom head circumferential weld, that was obtained by the licensee, the staff determined that a pattern of degradation, if.present, would have been detected. Furthermore, the staff determined that the licensee's proposed alternative provides reasonable assurance of structural integrity for the subject welds.
In Request for Relief RI-20, the licensee requested relief.from The Codethe Code-that requires required 100% surface examination of Weld RVD-BF-14.
the subject weld receive a 100% surface examination. The staff determined that the licensee can not perform the Code required examinations due to the To j proximity of.a rigid support, restricting access to one side of the weld.
satisfy Code requirements, removal of the rigid support by cutting or !
modification of the line would be. required,. resulting in a burden on the l licensee. Therefore, the Code required examination is impractical. j The licensee has proposed as an alternative to the Code requirements to j examine the accessible portion of the weld.. The licensee's examination resulted in a coverage of 83% of the subject weld. The staff has determined l l
that because a significant percent of coverage was obtained, degradation, if occurring,-would be detected. .Therefore, the licensee's proposed alternative l j
provides a reasonable assurance of structural. integrity for the subject weld.
J I. Pequest for Relief RI-21 the licensee has requested relief from Code i v m metric examination requirements for reactor vessel nozzle-to-vessel welds i and the CRD nozzle inside radius section. The staff has determine that for [
the nozzle-to-vessel welds and the N9 CRD nozzle, the component configuration, i insulation support rings, nozzle access hatches, and thermocouple pads and !
I instrument lines limit scanning, precluding complete Code volumetric coverage.
Therefore, compliance with Code requirements is. impractical. Providing access i
- to the examination areas for complete Code-required coverage would require i i
design modifications. Imposition of this requirement would cause a considerable burden on the licensee without a compensating increase in quality l and safety. >
The licensee has proposed as an alternative to examine the accessible portions !
of the subject nozzle-to-shell welds and the CRD nozzle inner radius section !
to the extent practical. Based on the percent of combined coverages of 27% to
. 70% for the subject nozzles in combination with the remote visual examination
- of the' accessible portions of the vessel interior and the VT-2 visual examination,* degradation, if occurring, would have been detected. Therefore, the license's proposed alternative provides reasonable assurance of structural l integrity of the subject welds. 1 The Code requirements pertaining to Request for Relief RI-22 specify that the {'
subject branch connection welds FWA-BJ-81, RAS-BJ-10, . and RBS-BJ-6A receive 100% volumetric and surface examinations. The staff has determined that complete Code-required volumetric examination coverage is impractical due to :
the configuration of the branch connections. To perform the complete
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l volumetric examination, design modifications or replacement of the branch connections would be necessary. Imposition of this requirement would cause a
! considerable burden on the licensee without a compensating increase in quality and safety.
l The licensee has proposed as an alternative, to perform the volumetric examinations to the extent practical. The licensee's examination resulted in +
coverages of 67% to 82% of the subject welds. Therefore, the staff determined that based on the coverages obtained, in combination with the Code-required ;
surface examination, significant degradation, if present, would have been ;
detected. Furthermore, the staff determined that the licensee's proposed '
alternative provides reasonable assurance of structural integrity for the subject welds.
The licensee withdrew Request for Relief RI-23 in its letter dated December 31, 1996.
3.0 CONCLUSION
S The staff has reviewed Amendment 4.1 to the second interval inservice Inspection Program Plan for the Cooper Nuclear Station. Based on this review, no deviations from regulatory requirements or commitments were identified.
The staff's conclusions for the licensee's Requests for Relief RI-06, ,
Revision 2,'RI-20, RI-21, RI-22 to the Code requirements are noted below. '
The staff evaluated request for Relief RI-06, Revision 2, and concluded that j the licensee has performed the examinations to the extent practical. Based on i the combined coverages obtained, reasonable assurance of structural integrity '
is provided. Therefore, for Request for Relief RI-06, Revision 2, relief remains granted pursuant to 10 CFR 50.55a(g)(6)(i).
The staff concluded that for Requests for Relief RI-20, RI-21, and RI-22, the Code requirements are impractical and that the licensee's proposed alternatives provide reasonable assurance of structural integrity of the subject welds. Therefore, pursuant to 10 CFR 50.55a(g)(6)(1), for Requests for Relief RI-20, RI-21, and RI-22, relief is granted. The licensee withdrew Request for Relief RI-23 in its letter dated December 31, 1996; therefore, it was not evaluated by the staff.
Principal Contributor: T. McLellan, DE/ECGB Date: June 6, 1997 l
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- - . TECHNICAL LETTER REPORT l- ON THE SECOND 10-YEAR INSERVICE INSPECTION INTERVAL i l AMENDMENT 4.1 l i
l - EBRASKA PUBLIC POWER DISTRICT
! COOPER NUCLEAR STATION DOCKET NO. 50-298
1.0 INTRODUCTION
By letter dated June 20, 1996, Nebraska Public Power District (NPPD) submitted ;
Amendment 4.1 to the second interval Inservice Inspection Program Plan for the l Cooper Nuclear Station. In a letter dated December 31, 1996, the licensee i submitted additional information in response to the Nuclear Regulatory Commission letter, dated October 24, 1996. The second 10-year inservice inspection (ISI) interval ended on February 29, 1996. The Idaho National i i Engineering Laboratory (INEL) staff has evaluated Amendment 4.1 to the program in the following sections.
2.0 EVALVATION i The licensee provided information, as applicable, for changes incorporated by Amendment 4.1 to the Inservice Inspection Program Plan for the Cooper Nuclear 1 Station. The Code of record for Cooper Nuclear Station, second 10-year interval, is the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, 1980 Edition, Winter 1981 Addenda.
The INEL staff has reviewed Amendment 4.1 to the Inservice Inspection Program.
As stated by the licensee, Amendment 4.1 consists of editorial changes, adjustments to the weld examination lists, and responses to NRC comments. In addition, the licensee submitted Revision 2 to Request for Relief RI-06 and four new requests, Requests for Relief RI-20, RI-21 RI-22, and RI-23. In the licensee's December 31, 1996 submittal, the licensee withdrew Request for Relief RI-23.
A. Proaram Chances In response to General Electric Service Information Letter No. 571, the licensee added augmented inservice inspections of instrument nozzle safe-ends to the ISI program. The licensee will perform supplemental volumetric examinations of the entire instrument nozzle safe end for nozzles N10, NilA/B, N12A/B, and N16A/B if flaws are detected during the scheduled surface examination performed in accordance with the ISI program. The surface examination will be extended to cover the entire instrument nozzle safe end. These examinations began in 1995.
B. Reauests for Relief The licensee updated the ISI Program with four new requests for relief and one revised request.
ENCLOSURE 2
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i Bl. Reauest for Relief RI-06. Revision 2. Examination Cateaory B-A. '
Items 81.11 and B1.30. Reactor Pressure Vessel Circumferential and :
Shell-to-Flance Welds l l l Code Reauirement: Table IWB-2500-1, Examination Category B-A, Items Bl.11 and 81.30 requires 100% volumetric examination of reactor pressure vessel circumferential and shell-to-flange welds as defined by Figures IWB-2500-1 and -4.
l Licensee's Code Relief Reauest: Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee submits for relief from performing the 100 percent volumetric examination of the following additional welds: HMC-BB-1, VCB-BC-5-1, VCB-BC-5-2, VCB-BC-5-3 (HMB-BB-1, HMB-BB-2, HMB-BB-3, HMB-BB-4, HMB-BB-5, HMB-BB-6, VLA-BA-1, VLA-BA-2, VLA-BA-3, VLB-BA-1, VLB-BA-2, VLB-BA-3, and VCB-BA-2 were evaluated in previous versions of this request for i relief and are therefore not addressed here.). I Licensee's Basis for Reauestina Relief: (as stated)
"The Cooper Nuclear Station construction permit was issued before the effective date of implementation for ASME Section XI and thus the plant was not designed to meet the requirements of inservice inspection; therefore,100% compliance is not feasible or practical.
" Access to the reactor vessel beltline region is not possible. The reactor vessel is insulated with permanent reflective insulation and surrounded by a concrete biological shield. The annular space between the inside diameter of the insulation and the outside diameter of the' reactor is a nominal 2 inches. There is no working space to iemove the insulation panels from the vessel, which precludes both direct and remote examination of the outside surface.
"The interior surface is clad and the arrangement of the vessel ,
internals, shroud and jet pumps make an internal volumetric !
examination of these welds impracticable for a meaningful l examination using the technology available at the beginning of the '
interval. Parts of longitudinal seams VLA-BA-1,' 2, and 3, however, appear to be accessible from openings around the recirculation riser ;
nozzles N2A, N2E, and N2H respectively. Again these seams are not '
100% accessible. The scanning surface would require a minimum of ,
17 inches from the weld. This surface area. is only available for a l few inches - closerc to a nozzle. i Note: The original version of this relief request was granted in SER dated January 27, 1986. Revision 2 was submitted to incorporate the following areas of limited examinations based on the Fall 1995 Refueling outage examinations. -
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" Access to the bott6m head circumferential weld HMC-BB-1 is limited due to the proximity of the vessel skirt. The configuration limits i scanning with the 60* probe. The total composite coverage is ;
approximately 86%. '
" Access to the shell to flange circumferential welds VCB-BC-5-1, -2,.
& -3, is limited due to the flange configuration and the proximity ,
of the vessel thermocouples. The configuration limits scanning with the 0*, 45*, and 60* probes. The thermocouples limit scanning with l both the 45* and 60* probes. The total composite coverage is approximately 74%."
Licensee's Proposed Alternative: (as stated) !
"In lieu of performing the Code required examinations, CNS proposes: !
(a) When the recirculation riser nozzle to vessel welds (Category B-D) are examined, a best effort examination of longitudinal shell welds in the beltline region, VLA-BA-1, 2, and 3, shall i be performed; '
(b) The accessible portions of the bottom head meridional welds, HMB-BB-1 through 6, will be examined on a best effort basis ;
when the vessel support skirt weld is examined; i (c) The beltline region weld areas shall be visually examined from !
the vessel interior during the Category B-N-1 and B-N-2 l examinations
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(d) The areas of the lower head and the shield annulus below the vessel shall be visually inspected during a system hydrostatic test; (e) The accessible portions of the bottom head circumferential weld, HMC-BB-1, and 150 inches of longitudinal seam shell weld above the shield wall shall be examined; (f) The accessible portiens of the bottom head circumferential weld, HMC-BB-1, shall be examined; and (g) The accessible portions of the shell to flange weld shall be examined."
Evaluation: The original version of this relief request was granted in an SER dated January 27, 1986. Revision 2 was submitted to incorporate the following limited examinations. The licensee has requested relief from the Code-required 100% volumetric coverage of the bottom head circumferential Weld HMC-BB-1 due to the proximity of the vessel skirt that limits scanning. Because of the close l proximity of the support skirt to the weld, scanning is restricted, l
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making it impractical to perform the examinations to the extent -
l required by the Code. For shell-to-flange circumferential Welds l VCB-BC-5-1, -2, & -3, scanning is limited due to the flange configuration and the proximity of the vessel thermocouples. As a l result, it is impractical to perform the examinations to the extent required by the Code. To obtain complete volumetric coverage for these welds, design modifications would be necessary. Imposition of this requirement would cause a considerable burden on the licensee.
l The licensee proposes to perform the volumetric examinations to the j extent practical on the subject welds. The licensee states that 86%
volumetric coverage of the shell-to-flange welds and 74 percent
, volumetric coverage of the bottom head circumferential weld was obtained. Based on the percent of coverage obtained, it is
, reasonable to conclude that a pattern of degradation, if present, would have been detected. As a result, reasonable assurance of continued structural integrity is provided.
Based on the review of the revised request, the INEL staff believes that the licensee performed the examinations to the extent practical, obtaining significant coverages. Therefore, the original conclusion is considered applicable to Revision 2 of the licensee's submittal.
[2nclusion: The original version of this relief request was granted in an SER dated January 27, 1986. Revision 2 was submitted to incorporate the limited examinations of the bottom head circumferential weld and the flange-to-shell welds. Based on the review of the revised request, the INEL staff believes that the licensee performed the examinations to the extent practical, obtaining significant coverages, providing reasonable assurance of continued structural. integrity. Therefore, pursuant to 10 CFR 50.55a(g)(6)(1), it is recommended that relief remain granted for Revision 2 to Request for Relief RI-06.
B2. Relief Reauest RI-20. Examination Cateaory B-F. Item B5.140.
Dissimilar Metal Butt Weids in Pipina Code Reauirement: ' Table IWB-2500-1, Examination Category B-F, Item B5.140 requires 100% surface examination of nozzle-to-safe end welds as defined by Figure IWB-2500-8.
Licensee's Code Relief ht Jest: Pursuant to 10 CFR 50.55a(g)(5)(iii), relief is requested from the Code-required 100% surface examination of Weld RVD-BF-14.
l Licensee's Basis for Reauestina Relief: (as stated) l l
"A rigid support is located adjacent to this 2 inch NPS stainless steel to carbon steel butt weld in the reactor drain line. The
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,- design of the support does not permit disassembly without cutting 'l l the support members. The support limits access to one side of the I i weld crown'such'that'only-1/4 inch of the adjacent base metal can be !
examined. The total surface examined is approximately 83%." j
. Licensee's Proposed Alternative Examination: (as stated)- . l l
"In lieu of performing-the Code required examinations, CNS proposes j
- to examine the accessible portions of Weld RVD-BF-14."
l Evaluation: The Code requires that the subject weld receive a 100%
surface examination. However, due to the proximity of a rigid . J support, access to one side of the weld is restricted. As a_ result, i
! the complete Code. required examination is impractical. In order to satisfy Code requirements, removal of the rigid support by cutting l or modification of the line would be required, resulting in a burden on the licensee.
The licensee is examining the accessible portion of the subject weld which results in 83% coverage. Based on the significant percent of coverage. obtained, it is reasonable to conclude that, degradation, if oc' curring, would be detected. As a result, reasonable assurance j of structural integrity is provided.
[pnclusion: Based on the abcve evaluation, it is concluded that performing the Code-required examination is impractical. The i examination, when performed to the extent practical, results in 83%
coverage. Based on the significant percent of coverage obtained, it is reasonable to conclude that, degradation, if occurring would be o detected. As a result, reasonable assurance of structural integrity
! is provided. Therefore,'it is recommended that relief be granted pursuant to 10 CFR 50.55a(a)(6)(i).
B3. Reauest for Relief. RI-21. Examination Cateoory B-D. Items B3.90 and B3.100. Reactor Vessel Nozzle-to-Vessel Welds Code Reauirement: Section XI, Table IWB-2500-1, Examination Category B-D, Item B3.90 requires 100% volumetric examination of reactor vessel nozzle-to-vessel welds as defined by Figure IWB-2500-7. ' Item B3.100 requires 100% volumetric examination
-of nozzle inner radius. sections as defined by Figure IWB-2500-7.
Licensee's Code Relief Reauest: Pursuant to 10 CFR 50.55a(g)(5)(iii), relief is requested from the Code-required l volumetric examinations of the following nozzle-to-shell welds including the nozzle inner radius for the N9 CRD nozzle:
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Nozzle Nozzle Access % Examined Number Description Restrictions NIA, B Recirculation Nozzle 32% :
Inlet configuration, i and insulation l support frame '
N2A-H, Recirculation Nozzle 40%
J&K Outlet configuration, and insulation !
support frame N3A-D Main Steam Nozzle 35% l configuration N4A&C Feedwater Nozzle 27% ,
configuration, '
insulation
.. support frame, .
and thermocouple pads N4B&D Feedwater Nozzle 31%
configuration, insulation support frame, and thermocouple ;
pads NSA,B Core Spray Nozzle 31% i configuration, ;
insulation l support frame, '
and thermocouple i pads i N6A, B Top Head Spray Nozzle 58%
configuration N7 Top Head Vent Nozzle 30%
configuration N8A,B Jet Pump Nozzle 76%
Instrumentation configuration, and insulation support frame N9 CRD Return Nozzle Nozzle 70% '
and Inner Radius configuration, and insulation support frame i
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l-- Licensee's Basis for Reauestina Relief: (as stated) i "The Cooper Nuclear Station construction permit was issued before l the effective date of implementation. for ASME Section XI and thus l the plant was not designed to meet the requirements of inservice inspection; therefore,100% compliance is not feasible or practical.
l The configuration of the nozzles, the design of the vessel insulation support rings and the nozzle access hatches, and interferences from thermocouple pads, instrument lines, etc.
l prevents 100% examination'of the required weld volumes. Alternate l angles were used to the extent practicable to increase the volume l examined.. The extent of the nozzle restrictiops and the total l volume examined is summarized on table RI-21-1."-
Licensee's Proposed Alternative Examination: (as stated)
! "In lieu of performing the Code required examinations, CNS proposes to examine the accessible portions of reactor vessel nozzle-to-vessel welds."
Evaluation:. The licensee has requested relief from Code volumetric examination requirements for the subject reactor vessel nozzle-to-vessel welds and the CRD nozzle inside radius section. Based on a i
review of the information provided, it has been determined that for the nozzle-to-vessel welds and the N9 CRD nozzle, the component configuration. insulation support rings, nozzle access hatches, and i thermocouple pads and instrument lines limit scanning, precluding l complete Code volumetric coverage. As a result, it is concluded ;
that. compliance with Code requirements is impractical. Providing access to the. examination areas for complete Code-required coverage would require design modifications. Imposition of this requirement would cause a considerable burden on the licensee.
The licensee is examining the accessible portion of the subject nozzle-to-shell welds and the CRD nozzle inner radius section to the extent practical, which results in coverages from 27% to 70%. Based on the percent of combined coverages obtainable for the subject nozzles in combination with the remote visual examination of the accessible portions of the vessel-interior and the VT-2 visual ,
examination, it is reasonable to conclude that, degradation, if 1 occurring, would be detected. As a result, reasonable assurance of :
structural ~ integrity is provided. j i
Conclusion:
Examination of the subject nozzle examination areas to l the extent required by Code is impractical'due to examination area j configuration and obstructions. These examinations in combination !
with remote visual examinations of the accessible internal surfaces i i
'Not included with this evaluation. l 1
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E and hydrostatic testing provide reasonable assurance of structural integrity. Therefore, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(1).
- 84. Reauest for Relief RI-22. Examination Cateaory B-J. Item B9.31. '
Examination of Class 1 Pine Branch Connection Welds Code Reauirement: Table IWB-2500-1, Examination Category B-J, Item B9.31 requires 100% surface and volumetric examination of branch pipe connection welds >4 inches as defined in Figure IWB-2500-10.
Licensee's Code Relief Reauest: Pursuant to 10 CFR 50.55a(g)(5)(iii), relief is requested from the 100%
volumetric examination coverage of Class 1 pipe branch connection l Welds FWA-PJ-81, RAS-BJ-10, and RBS-BJ-6A. '
Licensee's Basis for Reauestino Relief: (as stated)
"The configuration of the 8 inch branch weldolet to 18 inch pipe weld FWA-BJ-81, prevents complete ultrasonic examination of the code '
required volume. The configuration of the weldolet prevents !
examination from the branch side of the weld and limits the i examination to one direction from the other side. No supplemental l examinations to increase the coverage were possible. The total !
volume examined is approximately 82%. j "The configuration of the 6 inch branch to 20 inch elbow weld RAS-BJ-10, prevents complete ultrasonic examination of the code required volume. The branch connection is welded to the extrados of the elbow. The angle between the branch connection and the elbow l changes as the probe is scanned circumferentially around the branch.
Where the angle is most acute, the sound can not reach the root of the weld and the configuration of the branch prohibits the use of larger angles. Supplemental examinations were performed to increase the coverage. The total volume examined is approximately 82%. ,
1 "The configuration of the 4 inch branch weldolet to 28 inch pipe l weld RBS-BJ-GA, prevents complete ultrasonic examination of the code i required volume. The configuration of the weldolet prevents ,
examination from the branch side of the weld and limits the !
examination to one direction from the other side. No supplemental examinations to increase the coverage were possible. The total volume examined is approximately 67%."
Licensee's Proposed Alternative Examination: (as stated)
"In lieu of performing the Code required examinations, CNS proposes l to examine the accessible portions of branch connection welds ,
FWA-BJ-81, RAS-BJ-10, and RBS-BJ-6A." l
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j l Evaluation: The Code requires that the subject branch connection welds receive 100% volumetric and surface examinations. The licensee stated that 67% to 82% volumetric coverage of the subject examination areas was obtained. Based on the review of the l information provided, it has been determined that complete Code- ,
! required volumetric examination coverage is impractical due to the l configuration of the branch connections. To perform the complete-l volumetric examination, design modifications or replacement of the l branch connections with those of a configuration that provides for complete coverage would be required. Imposition of this requirement would cause a considerable burden on the licensee.
The licensee proposes to perform the volumetric examinations to the extent practical, resulting in coverages of 67% to 82%. Based on the coverages obtained, in combination with the Code-required surface examination, it can be concluded that significant degradation, if present, would be detected. As a result, reasonable assurance of structural integrity is provided.
Conclusion:
Based on the above evaluation, it has been determined that obtaining the Code-required examination volume coverage for the subject branch connection welds is impractical for Cooper Nuclear Station. When considering the percent of examination coverage obtained for the subject branch connection welds, in combination with the surface examinations, it can be concluded that significant !
degradation, if present, would be detected. As a result, reasonable I assurance of structural integrity is p'rovided. Therefore, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).
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3.0 CONCLUSION
The Iut staff has reviewed Amendment 4.1 to the second interval Inservice ,
l Inspection Program Plan for the Cooper Nuclear Station. Based on this review, i no deviations from regulatory requirements or commitments were identified. l The INEL staff evaluated Requests for Relief RI-06, Revision 2, RI-20, RI-21, ,
RI-22. For Request for Relief RI-06, Revision 2, it has been determined that the licensee has performed the examinations to the extent practical. Based on the combined coverages obtained, reasonable assurance of structural integrity is provided. Therefore, it is recommended that for Request for Relief RI-06, Revision 2, relief remain granted pursuant to 10 CFR 50.55a(g)(6)(i).
I For Requests for Relief RI-20, RI-21, and RI-22, the licensee proposes to examine the subject welds to the extent practical. Based on the coverages l obtained for the weld segments examined, reasonable assurance of structural integrity is provided. Therefore, pursuant to 10 CFR 50.55a(g)(6)(i), it is recommended that for Requests for Relief RI-20, RI-21, and RI-22, relief be granted.
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