ML17335A461
| ML17335A461 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 12/29/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17335A460 | List: |
| References | |
| NUDOCS 9901080058 | |
| Download: ML17335A461 (21) | |
Text
1 UNITED STATES NUCLEAR REGULATORY COMMISSION gp,8 RED
~o I
0 C
O COoP WASHINGTON, D.C. 2050540M Vr
~o
++*++
SAFETY EVALUATIONBYTHE OFFICE OF NUCLEAR REACTOR REGULATION RELATEDTO EVALUATIONOF THE THIRD 10-YEAR INTERVALINSERVICE INSPECTION PROGRAM PLAN AN ASSOCIATED RE UESTS FOR RELIEF INDIANAMICHIGANPOWER COMPANY DONALDC. COOK NUCLEAR PLANT UNITS 1 AND2 DOCKET NOS. 50-315 AND 50-316
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 (B8PV) Code and applicable addenda as required by 10 CFR 50.55a(g),
except where specific relief has been granted by the Commission pursuant to 10 CFR 50.55a(6)(g)(i).
10 CFR 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 difficultywithout 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 lnservice 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 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. The applicable edition of Section XI of the ASME Code for the D.C. Cook Nuclear Power Plant, Units 1 and 2 third 10-year inservice inspection (ISI) interval is the 1989 Edition except that the extent of examination for Class 1, examination category B-J, has been determined by the requirements of the 1974 Edition through summer 1975 Addenda as permitted by 10 CFR 50.55a(b).
By letter dated January 25, 1996, Indiana Michigan Power Company (licensee) submitted its third 10-year interval inservice inspection program plan and associated requests for relief for'.C.
Cook Nuclear Plant, Units 1 and 2.
In addition, the licensee submitted additional information in its letters dated September 10, 1996, November 7, 1996, and July 8, 1998.
'P90i080058 98i229 PDR ADQCK 050003i5 P
~
~
+ k 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 in support of its third 10-year interval inservice inspection program plan and associated requests for relief for D.C. Cook Nuclear Plant, Units 1 and 2.
Based on the results of the review, the staff adopts the contractor's conclusions and recommendations presented in the Technical Letter Report (TLR) attached.
The staff determined that there were no deviations from the regulatory requirements identified in the licensee's Second Ten-Year Interval Inservice Inspection Program Plan for D.C. Cook Nuclear Plant, Units 1 and 2.
Request for Relief No. 1, (Units 1 &2): ASME Code,Section XI, Examination Category B-A, Items B1.11 and B1.12 require 100% volumetric examination of the reactor vessel shell welds as defined in Figures IWB-2500-1 and IWB-2500-2, respectively.
Examination Category B-D, Item B3.90 requires 100% volumetric examination of the reactor vessel, nozzle-to-vessel welds as defined in Figure IWB-2500-7.
Note: The licensee satisfied the augmented RPV examination required by 10 CFR 50.55a(g)(6)(ii)(A) with the proposed alternative that was evaluated and authorized in NRC letters dated July 26, 1996 and October 7, 1998.
Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee requested relieffrom performing 100%
volumetric examination of those vessel welds where the average examination coverage is less than or equal to 90% of the Code-required examination coverage.
In lieu of the volumetric examination requirements ofASME Section XI and 10 CFR 50.55a(g)(6)(ii)(A), the RPV shell welds which have examination coverages 90% or less willbe augmented by the system leakage tests and VT-2 visual examinations during the third 10-year interval. These examinations willbe conducted in accordance with ASME Section XI, Table IWB-2500-1 Category B-P and Code Case N498-1.
Table RR-1 (Units 1 8 2)
Weld ID 1-RPV-D Exam Area Lower shell-to-lower head Coverage 69%
Limitation '-'..
Core barrel support lugs 1-RPV-VA1 Upper shell long. @
26.5'-RPV-VA2 Upper shell long.
@146.5'-RPV-VC1 Lower shell long. @
60'-RPV-VC2 Lower shell long.
@180'-RPV-VC3 Lower shell long. @ 300 80%
62%
80%
80%
80 Outlet integral extension Core barrel support lugs Table RR-1 (Units 1 8 2) ~.,",':-,=,
Weld ID.
1-N1B 1-N2B 1-N3B 1-N4B 2-RPV-D 2-RPV-VA1 ExamArea '=.:. =- ',,
Outlet nozzle-to-shell @
202'utlet nozzle-to-shell @
338'utlet nozzle-to-shell @22' Outlet nozzle-to-shell @158' Lower shell-to-lower head Upper shell long.
@22'overage'9%
39%
59 39%
70% (80')
80% (90*)
'Limitation Outlet integral extension Core barrel support lugs and anti-rotation lugs 2-RPV-VA2 2-RPV-VA3 2-N1-0 2-N2-0.
2-N3-0 2-N4-0 Upper shell long.
@113'ower shell long.
@247'utlet nozzle-to-shell @
338'utlet nozzle-to-shell @
202'utlet nozzle-to-shell @
158'utlet nozzle-to-shell @
22'0%
(90')
8Q% (9Q*)
60%
60%
60 60%
Outlet integral extension Outlet integral extension
- Denotes coverage stated in July 29, 1996 submittal.
The Code requires 100% volumetric examination of the subject RPV welds.
However, complete examination of the RPV shell welds is restricted by physical obstructions, such as core support lugs and nozzle integral extensions, that make the volumetric examination impractical to perform to the extent required by the Code. To meet the Code requirements, the RPV would require design modifications to allow access for examination.
Imposition of this requirement would create a burden on the licensee.
The licensee can examine a considerable portion (~62%) of each of the subject shell welds.
In addition, there are other RPV shell welds that can be examined to the extent required by the Code. Therefore, the examinations that can be performed would detect any significant patterns of degradation that may occur and the examinations performed to the extent practical provide reasonable assurance of the continued structural integrity of the RPV shell welds.
For the RPV nozzle-to-vessel welds, the estimated coverage appears low and has not been justified.
Therefore, relief is denied for the RPV nozzle-to-vessel welds. To be found acceptable, the licensee should submit additional information describing the limiting condition (i.e., component configuration, search unit size, obstruction size, etc.) and alternatives considered or used to maximize examination coverage (i.e., different angles, smaller search units). Sketches and/or drawings depicting the limiting conditions should be provided if appropriate.
1 3
For the RPV shell welds, the Code required examinations are impractical and the licensee can not meet the Code requirements.
The RPV shell weld examinations that can be partially inspected in conjunction with the Code required VT-2 examinations provide reasonable assurance ofthe structural integrity of the subject welds. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i) for the subject RPV shell welds at D. C. Cook, Unit 1 for the current interval.
In addition, the staff concluded that relief is granted pursuant to 10 CFR 50.55a(g)(6)(i) for the subject Unit 2 RPV shell welds, provided that the licensee meets the coverage stated in the July 29, 1996, submittal.
For the RPV nozzle-to-vessel welds, the staff concluded that the licensee has not provided adequate justification for the determination that the Code requirements are impractical.
Therefore, relief is denied for the RPV nozzle-to-vessel welds.
Request for Relief No. 2 (Units 1 8 2): ASME Code,Section XI, Examination Category B-F, Item B5.10 requires 100% volumetric and surface examination of nozzle-to-safe end welds as defined in Figure IW8-2500-8.
Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed an alternative to the Code-required 100% surface examination for the main recirculation loop nozzle-to-safe welds listed below.
1-RPV-1-01 1-RPV-2-01 1-RPV-3-01 1-RPVA-01 1-RPV-1-02 1-RPV-2-02 1-RPV-3-02 1-RPVA-02 2-RPV-1-01 2-RPV-2-01 2-RPV-3-01 2-RPV-4-01 2-RPV-1-02 2-RPV-2-02 2-RPV-3-02 2-RPV4-02 The Code requires 100% volumetric and surface examinations for the reactor vessel nozzle-to-safe end butt welds. The licensee proposed to perform volumetric examination of the outside surface in lieu of the Code-required surface examination.
The licensee demonstrated detection of outside diameter (OD) notches using ultrasonic examination procedures from the inside diameter (ID) surface.
As stated by the licensee, the notches used for the demonstration were smaller than the allowable planar flaws provided in Tables IWB-3524-1 and -2.
Performing a volumetric examination of the RPV nozzle-to-safe end welds using automated examination techniques from the ID surface has been fou'nd acceptable at other plants, provided that the proposed ultrasonic technique was demonstrated on OD surface cracks rather than notches, and that the full-volume of each weld would be examined.
At D. C. Cook, the licensee has committed to examine the fullvolume of each weld including /~inch of the base metal on either side of the weld, but has not demonstrated the ultrasonic technique using cracks.
., Although it appears that the demonstration was performed using reflectors that were sufficiently small, the detection of cracks of the same size can be signiflicantly more difficult. Therefore, the staff concluded that the licensee has not adequately demonstrated the effectiveness of the proposed alternative examination to provide an acceptable level of quality and safety.
Therefore, the licensee's proposed alternative examination is not acceptable.
To be found acceptable, the licensee should demonstrate the proposed technique on cracks rather than notches.
Request for Relief No. 3 (Units 1 & 2): ASME Code,Section XI, Examination Category B-A, Item 81.30 requires 100% volumetric examination of the reactor vessel shell-to-flange weld as defined in Figure IWB-25004 Table IWB-2500-1, Examination Category B-A, Note 3 allows deferral of the shell-to-flange weld to the end of the interval provided that a partial examination is conducted from the flange face.
Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed to defer the shell-to-flange weld until the end of the third 10-year interval without performing a partial examination from the flange face. The licensee stated:
"Examination of the RPV shell-to-flange weld willbe performed at the end of the third inspection period using the automated examination equipment scheduled for the third inspection period of the third 10-year interval."
The Code requires volumetric examinations of reactor vessel shell-to-flange weld. Generally, this requires a portion (- 1/3) of the weld to be examined each period. The Code allows deferral of examinations from the shell side of the weld, provided that a partial examination is conducted from the flange face. As an alternative to the Code requirements, the licensee proposed to defer the entire examination until the end of the interval.
Deferring the examination until the third period would allow two-thirds of the examination to exceed 10 years since they were last examined.
This is in conflict with the sampling philosophy of Section XI. Furthermore, the licensee has not provided sufficient technical justification
,demonstrating that the proposed alternative provides an acceptable level of quality and safety and that the schedule for future examinations willbe such that 10 years willnot elapse between examinations.
The staff concluded that the licensee's proposed alternative, to defer the shell-to-flange weld examination without performing a partial examination from the flange face, is not in accordance with Section XI. In addition, the licensee did not demonstrate how the proposed alternative provides an acceptable level of quality and safety. Therefore, the staff concluded that the licensee's proposed alternative is not acceptable.
Request for Relief No. 4 (Units 1 &2): ASME Code,Section XI, Examination Category B-A, Item B1.21 requires 100% volumetric examination of the accessible lengths of the reactor vessel circumferential head welds as defined in Figure IWB-2500-3.
Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee requested relief from performing the Code-required volumetric examination of the closure and lower head dollar plate welds.
The licensee proposed that in lieu of the volumetric examination requirements ofASME Section XI, a system leakage test and VT-2 examination willbe conducted for this inspection interval.
These examinations willbe conducted per the requirements ofASME Section XI, IWB-2500, Category B-P. Additionallythe accessible length of one closure head meridional weld (which intersects the closure head dollar plate weld) is volumetrically examined during the inspection interval per ASME Section XI, IWB-2500-1, Category B-A. Based on the Leakage Detection System, the overall level of plant safety willnot be reduced by the proposed relief request.
In the July 8, 1998, submittal, the licensee stated:
"Code relief request no. 4 for both units did state that one of the meridional welds is volumetrically examined during the inspection interval as a means of ensuring structural integrity. However, the third 10-year interval ISI program indicates that the accessible lengths of all meridional welds are scheduled for examination during the third inspection interval in accordance with the code requirements.
An amendment to AEP:NRC:096AJ, code relief request no. 4 for units 1 and 2, willbe submitted by August 31, 1998, to correct this mis-statement."
The Code requires 100% volumetric examination of the subject RPV circumferential head welds.
However, access to these welds is completely restricted by the lower head instrument penetrations and control rod drive housings.
These physical obstructions make the Code examination requirements impractical to meet. To meet the Code requirements, the RPV lower head and closure head would require design modifications to allow access for examination.
Imposition of the Code requirements would result in a burden on the licensee.
The licensee willexamine the accessible length of all meridional head welds during the third ISI interval in addition to the periodic VT-2 visual examination for leakage.
Furthermore, all other RPV circumferential welds are examined each interval. These examinations would detect any significant patterns of degradation that may occur and the examinations provide reasonable assurance of the structural integrity of the RPV head welds.
The staff concluded that the Code-required volumetric examination is impractical to perform at D.C. Cook, Units 1 and 2, and that reasonable assurance of structural integrity is provided by the RPV weld examinations that can be performed.
Therefore, pursuant to 10 CFR 50.55a(g)(6)(i), this relief is granted and the alternative imposed forthe current interval as requested.
Request for Relief No. 5 (Units 1 & 2): ASME Code,Section XI, Category C-F-1, Item C5.21 requires 100% volumetric and surface examination of Class 2 circumferential piping > NPS 2 and < NPS 4 as defined in Figure IWC-2500-7.
0
~ l
~ r
~
i ~
0 Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee requested relief from the surface and volumetric examinations of the following Feedwater and Main Steam pipe-to-flued head welds.
(Note: ln the July 8, 1998, submittal, the licensee provided the following list of items for Requests for Relief Nos. 5 and 6, but did not differentiate the items for each request.
Therefore, ail the components for Request for Relief Nos. 5 and 6 are listed below.)
1-FW-1 1-01S
~
1-FW-13-01S 1-FW-16-01S 1-FW-18-01S 1-MS-1-10F 1-MS-1-12F 1-MS-6-10F 1-MS4-12F
'-MS-10-09F 1-MS-10-11F 1-MS-14-09F 1-MS-14-1 1F 2-FW-74-1 6S 2-FW-75-16S 2-FW-76-16S 2-FW-77-16S 2-MS-89-11F 2-MS-89-13S 2-MS-91-09F 2-MS-91-11F 2-MS-93-09F 2-MS-93-11S 2-MS-95-09F 2-MS-95-1 1S I'he licensee proposed in lieu of the ASME Section XI requirements, the first accessible weld outside each penetration willbe examined with the Code-required volumetric and surface examinations.
The Code requires surface and volumetric examinations of the subject Class 2 piping welds.
However, these welds are totally enclosed in a containment penetration sleeve.
This prevents access to perform the Code-required examinations of the subject wefds. Therefore, the surface and volumetric examinations are impractical for these Class 2 welds. To meet the Code examination coverage requirements, design modifications replacing the Class 2 piping at each location would be necessary to allow access for examination.
Imposition of this requirement would create a burden on the licensee.
The licensee has proposed to examine the first accessible weld outside each penetration.
Since examination of an adjacent weld willbe performed, the staff concluded that the licensee's proposed alternative willdetect a pattern of generic degradation, ifpresent.
Therefore, the licensee's proposed alternative provides reasonable assurance of continued inservice structural integrity of the subject component and is acceptable.
The staff concluded that surface and volumetric examinations are impractical to perform on the subject welds since they are totally enclosed in a containment penetration sleeve.
Examination
~ i
)
'V of adjacent welds should detect a pattern of generic degradation, ifpresent.
This willprovide reasonable assurance of structural integrity. Therefore, relief is granted as requested and the alternative imposed, pursuant to 10 CFR 50.55a(g)(6)(i), for the current interval.
Request for Relief No. 6 (Units 1 & 2): ASME Code,Section XI, Examination Category C-F-1, Item C5.21 requires 100% volumetric and surface examination of Class 2 circumferential piping
> NPS 2 and < NPS 4 as defined in Figure IWC-2500-7.
Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee requested relief from the surface and volumetric examinations of the Main Steam pipe-to-flued head welds listed below. (Note: In the July 8, 1998, submittal, the licensee provided the following list of items for Requests for Relief Nos. 5 and 6, but did not differentiate the items for each request.
Therefore, all components for Request for Relief Nos. 5 and 6 are listed below.)
1;FW-1 1-01S 1-FW-1 3-01S 1-FW-16-01S 1-FW-1 8-01S 1-MS-1-1 OF 1-MS-1-12F 1-MS-6-10F 1-MS-6-12F 1-MS-10-09F 1-MS-10-11F 1-MS-14-09F 1-MS-14-11F 2-FW-74-16S 2-FW-75-16S 2-FW-76-16S 2-FW-77-16S 2-MS-89-1 1F 2-MS-89-13S 2-MS-91-09F 2-MS-91-11F 2-MS-93-09F 2-MS-93-11S 2-MS-95-09F 2-MS-95-11S The licensee proposed an alterative in lieu of the ASME Section XI requirements, the first accessible adjacent weld in one steam line willbe examined with the Code-required volumetric and surface examinations.
The Code requires surface and volumetric examinations of the subject Class 2 piping welds.
However, these welds are totally enclosed in a whip restraint.
This prevents access to perform the Code-required examinations of the subject welds. The staff concluded that the surface and volumetric examinations are impractical for these Class 2 welds. To meet the Code examination coverage requirements, design modifications replacing the whip restraint or temporarily providing support and cutting out the whip restraint would be necessary to allow access for examination.
Imposition of this requirement would create a burden on the licensee.
~- v-A.
The licensee has proposed to examine the first accessible adjacent weld in one steam line. The staff determined that examination of an adjacent weld, in lieu of examination of an inaccessible penetration weld, would detect any significant patterns of generic degradation that may occur.
The staff also determined that the licensee's proposed alternative provides reasonable assurance of structural integrity of the subject components.
However, the licensee has limited their proposed alternative to the first accessible weld on one steam line, and it appears that one weld may be substituted for many welds. The staff determined that the licensee's proposed alternative is only acceptable ifthe licensee examines an alternative weld for each inaccessible penetration weld contained in this request.
The staff concluded that the Code-required examinations are impractical to perform on the subject welds, and that reasonable assurance of structural integrity'is provided by examination of the first accessible adjacent weld. Therefore, pursuant to 10 CFR 50.55a(g)(6)(i), relief is granted and the alternative imposed for the current interval, provided that the licensee examines an alternative weld for each inaccessible penetration weld for which relief is requested.
Request for Relief No. 7 (Unit 2): ASME Code,Section XI, Examination Category B-D, Item B3.30, Pressurizer Nozzle-To-Vessel Welds The licensee withdrew Request for Relief No. 7 in its letter dated July 8, 1998.
Proposed Alternative N-521 (Units 1 & 2): The ASME Code,Section XI, Examination Category B-D, Items B3.90 and B3.100 requires 100% volumetric examination, as defined by IWB-2500-7, of at least 25% but not more than 50% of reactor vessel nozzle-to-vessel welds and nozzle inside radius sections by the end of the first period.
Examination Category B-F, Item B5.10 requires 100% surface and volumetric examination, as defined by Figure IWB-2500-8, of dissimilar metal nozzle-to-safe end welds. Tliese examinations may be coincident with the vessel nozzle examinations.
Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed to use Code Case N-521 Alternative Rules forDeferral ofInspections ofNozzle-to-Vessel Welds, Inside Radius Sections, and Nozzle-to-Safe End Welds ofa Pressurized Water Reactor (PWR) Vessel as an alternative to the Code scheduling requirements.
The licensee stated:
"As an alternative to the requirements of the 1989 edition of the ASME Section XI code, it is proposed to perform all the nozzle to vessel, nozzle to safe end welds, and inside radius section examinations in the third period of the third interval" The Code requires volumetric and surface examination of the subject nozzle-to-vessel welds, inside radius sections, and nozzle-to-pipe welds during each 10-year ISI interval. At least 25%,
but not more than 50% (credited), of the nozzle-to-vessel welds and inside radius sections must be examined by the end of the first inspection period, and the balance completed by the end of the 10-year interval. The sequence of examinations established for the subject welds during the first inspection interval shall be repeated during each successive interval.
The licensee proposed to implement Code Case N-521, in lieu of the Code requirements, which allows deferral of examination of nozzle-to-vessel welds, inside radius sections, and nozzle-to-safe end welds to the end of the inspection interval. The Code Case allows this deferral provided that:
- 1) no inservice repairs or replacements by welding have ever been performed on the subject welds, 2) none of the subject examination areas contain identified flaws or relevant conditions that currently require successive inspections, and 3) the unit is not in the first inspection interval. In addition, the subject examinations must be performed such that successive examinations do not exceed 10 years, except where the length of a 10-year interval is adjusted in accordance with IWA-2430. This condition appears in the draft version of Regulatory Guide 1.147, Revision 12.
The use of Code Case N-521 is denied, because the staff concluded that examination of the nozzles would be scheduled such that the intervals between successive examinations would exceed 10 years.
Proposed Alternative N-524 (Units 1 8 2): ASME Code,Section XI, Examination Categories B-J, C-F-1, and C-F-2, Items B9.12, C5.12, C5.22, C5.52, and C5.62, require surface and volumetric examination of Class 1 and 2 longitudinal piping welds.
Items B9.22, C5.42, and C5.82 require surface examination of Class 1 and 2 longitudinal piping welds. The examination volume/surface area includes 2.5t at the intersection with circumferential welds required to be examined.
Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed the use of Code Case N-524 in lieu of the Code requirements for Class 1 and 2 longitudinal piping welds. The licensee stated:
"As an alternative to the requirements of the 1989 Edition ofASME Section XI code, it is proposed to examine class 1 and 2 longitudinal piping welds in accordance with the requirements stated in ASME Code Case N-524."
The licensee proposed to use the alternative provisions of Code Case N-524, in lieu of performing the surface and volumetric examinations, as applicable, of the longitudinal welds in Class 1 and 2 piping. Code Case N-524 allows licensees to examine the potentially critical portions of the longitudinal welds (the portions that intersect circumferential welds) in conjunction with examination of the circumferential welds.
The licensee's alternative is based on the position that, due to fabrication controls and lack of susceptibility to the conditions that lead to failure, longitudinal welds are unlikely to fail. The potentially critical portions of the longitudinal welds are the portions that intersect circumferential welds; these regions willbe examined in conjunction with the circumferential welds.
Additionally, where the longitudinal weld cannot be identified, 100% of the circumferential weld willbe examined for flaws parallel and transverse to the weld to ensure that the longitudinal/circumferential weld intersection is examined.
With this alternativ, the most critical area of the longitudinal weld is examined, thus providing an acceptable level of quality and safety.
Based on the quality of longitudinal welds and the extent of examinations performed, this provides assurance of structural integrity.
The staff concluded that the licensee's proposed alternative provides an acceptable level of quality and safety. Therefore, the staff authorizes the licensee's proposed alternative, the use of Code Case N-524, pursuant to 10 CFR 50.55a(a)(3)(i). The use of the Code Case N-524 is
1l II i) authorized for the current interval or until such time as the Code Case N-524 is published. in a future revision of Regulatory Guide 1.147. Atthat time, ifthe licensee intends to continue to implement Code Case N-524, the licensee should followall provisions of the Code Case with the limitations issued in Regulatory Guide 1.147, ifany.
Proposed Alternative N-509 (Units 1 & 2): ASME Code,Section XI, Tables IWX(B,Cand D) 2500-1 requires examination of integrally-welded attachments as specified for Examination Categories B-H, B-K, C-C, D-A, D-B, and D-C. The Code stipulates volumetric or surface examinations, as appropriate, and the extent of examinations.
Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed to use Code Case N-509 Alternative Rules forthe Selection and Examination ofClass 1, 2, and 3 Integrally-Welded Attachments,Section XI, Division 1 as an alternative to the Code requirements for the examination of Class 1, 2, and 3 integrally-welded attachments.
The licensee stated:
"As an alternative to the requirements of the 1989 edition of the ASME Section XI Code,"
it is proposed to perform examination of welded attachments for vessels, piping, pumps and valves in accordance with Code Case N-509.
The licensee has proposed, as an alternative to the Code requirements, to apply the requirements of Code Case N-509 for the examination of integrally-welded attachments on Class 1;-2, and 3 piping and components.
Code Case N-509 provides alternative sampling requirements for the examination of Class 1, 2, and 3 integral attachments.
Code Case N-509 has been found acceptable for use at other plants provided that the licensee's alternative includes examining a minimum sample of 10% of the total number nonexempt piping, pumps, and valve integral attachments, distributed among Class 1, 2, and 3 systems.
The licensee has not provided a clear alternative regarding the stated condition. The'staff concluded that the licensee's proposed alternative is not acceptable.
For the staff to find the use of Code Case N-509 acceptable, the licensee must include in its alternative that it willinspect a minimum of 10% of the total number of integral attachments to piping, pumps, and valves, distributed among Class 1, 2, and 3 systems to provide assurance of structural integrity.
Proposed Alternative N491-1 (Units 1 & 2): Use of Code Case N-491-1, Alternative Rules for Examination of Class 1, 2, 3, and MC Component Supports ofLight-Water Cooled Power Plants.
The Code requires the examination of component supports as specified in Subsection IWF Examination Category F-A. Component supports selected for examination shall be the supports of those components that are required to be examined under IWB, IWC, and IWD during the first inspection interval.
Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed the use of the Code Case NP91-1 for the examination of Class 1, 2, 3, and MC Component Supports.
The licensee stated:
"As an alternative to the requirements of the 1989 edition of the ASME Section XI code, it is proposed to perform examination of component supports in accordance with the requirements established in ASME approved Code Case NQ91-1."
~
The licensee has proposed the use of Code Case N491-1 which has not yet been approved for general use by reference in NRC Regulatory Guide 1.147, Inseni ice Inspection Code Case Acceptability. However, the initial version of Code Case N491 has been approved for use by the NRC and comparison of the two revisions indicates that the only change between the two is Paragraph 1220, "Snubber Inspection Requirements".
In Code Case N491-1, this paragraph states that the ISI requirements for snubbers shall be in accordance with the Section XI Edition and Addenda specified in the Owne'r's Inservice Inspection Program.
In Code Case N491; ISI requirements for snubbers are in accordance with the requirements of IWF-5000. The staff concludes that Code Case NC91-1 is essentially identical to Code Case N-491 and willprovide assurance of component integrity. The selection or examination rules of Code Case N491-1are basically the same as in Code Case NQ9, which was previously approved for use by the NRC in Regulatory Guide 1.147.
The staff concluded that the use Code Case N491-1 provides an acceptable level of quality and safety; therefore, the licensee's proposed alternative, to use this Code Case, is authorized
, pursuant to 10 CFR 50.55a(a)(3)(i).
The use of the Code Case should be authorized for the current interval or until such time as the Code Case is published in a future revision of Regulatory Guide 1.147. At that time, ifthe licensee intends to continue to implement Code Case N491-1, the licensee should follow all provisions of the Code Case with the limitations issued in Regulatory Guide 1.147, ifany.
3.0 CONCLUSION
The staff concluded that there were no deviations from the regulatory requirements or commitments that were identified in the licensee's Third Ten-Year Interval Inservice Inspection Program Plan, for D.C. Cook Nuclear Plant, Units 1 and 2.
The staff concluded that the Code requirements for Request for Relief No.1 (Unit 1) RPV shell welds are impractical and that the licensee's proposed alternative provides reasonable assurance of structural integrity of the subject compone'nts.
Therefore, relief is granted pursuant to 10 CFR 50,55a(g)(6)(i) for the Unit 1 RPV shell welds.
For Request for Relief No.1(Unit 2) RPV shell welds, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i) provided the licensee meets the coverage obtained during the augmented RPV examination.
In addition, the staff concluded that the licensee's proposed alternative with the above provision provides reasonable assurance of structural integrity of the subject components.
Request for Relief No. 1 (Units 1 and 2) is denied for the RPV nozzle-to-vessel welds, because the licensee did not provide sufficient justification to support the determination that the Code requirement is impractical.
Requests for Relief Nos. 2 and 3, are denied, because the licensee did not provide sufficient justification to support the determination that the alternatives provide an acceptable level of quality and safety.
4l ~-$
The staff concluded that certain inservice'xaminations cannot be performed to the extent required by Section XI of the ASME Code.
In the case of Requests for Relief No. 4, 5, and 6, the licensee has demonstrated that specific Section XI requirements are impractical. The staff also concluded that licensee's proposed alternatives provide reasonable assurance of structural integrity of the subject components.
Based on this determination, relief is granted and the alternatives imposed, pursuant to 10 CFR 50.55a(g)(6)(i), for the current interval. The relief grante'd is authorized by law giving due consideration to the burden upon the licensee ifthe requirements were imposed on the facility.
The staff concluded that the licensee's proposed Alternatives NP91-1 and N-524, provide an acceptable level of quality and safety.
Pursuant to 10 CFR 50.55a(a)(3)(i), the staff concluded that licensee's proposed alternatives to use Code Cases NA91-1 and N-524 are authorized for the current interval or until such time as the Code Cases are published in a future revision of Regulatory Guide 1.147. At that time, ifthe licensee intends to continue to implement the Code Cases, the licensee should followall provisions in Code Cases N491-I and N-524 with limitations issued in Regulatory Guide 1.147, ifany.
Request for Relief No. 7 was withdrawn by the licensee in its letter dated July 8, 1998.
The staff denied proposed Alternatives PA-521 and PA-509 because the licensee did not provide sufficient justification to conclude that they would provide an acceptable level of quality and safety.
Principal Contributor: Thomas McLellan Date:
December 29, 1998
C Jl