ML20212A886

Safety Evaluation Authorizing First & Second 10 Yr Interval Inservice Insp Plan Requestss for Relief RR-01

ML20212A886
Person / Time
Site:	Limerick
Issue date:	09/13/1999
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20212A881	List: ML20212A875 ML20212A886
References
NUDOCS 9909170174
Download: ML20212A886 (24)

Text

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p- -4 UNITED STA'ES j j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2055M001

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION Of THE FIRST AND SECOND 10-YEAR INTERVAL INSFRVICE INSPECTION PLAN REQUESTS FOR RELIEF NOS.

RR-01 (PARTS 1 & 2). RR-05. RR-11. RR-12 (PARTS 1 THROUGH 5). AND RR-23 FOR LIMERICK GENERATING STATION. UNITS 1 AND 2 PECO ENERGY COMPANY DOCKET NOS. 50-352 AND 50-353

1.0 INTRODUCTION

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 (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 j pursuant to 10 CFR 50.55a(6)(g)(i). Pursuant to 10 CFR 50.55a(a)(3), alternatives to the  !

requirements of paragraph (g) may be used, when authorized by the U.S. 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 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 pre-service examination requirements, set forth in the ASME Code,Section XI, " Rules for Inservice inspection [ISI) 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 ISI interval and subsequent intervals comply with the requirements in  !

l the latest edition and addenda of Section XI of the ASME Code incorporated by reference in l 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the i lirnitations and modifications listed therein. The Code of record for Limerick Generating Station (LGS), Unit 1, second ISI interval, which began February 2,1997, is the 1986 Edition of Section XI of the ASME B&PV Code. The applicable edition of Section XI of the ASME Code for LGS Unit 2, first 10-year ISI interval, which began January 8,1990, is also the 1986 Edition. Upon completion of the first ISI interval for LGS, Unit 2, the ISI programs for both LGS Units 1 and 2, will be updated to the same edition of Section XI that will be in effect 12 months prior to the start of the LGS, Unit 2, second inspection interval, as required by 10 CFR 50.55a(g)(4)(ii).

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J 2.0 EVALUATION By letter dated January 30,1998, as supplemented on September 25,1998, and March 11, and April 15,1999, PECO Energy Company (PECO Energy, the licensee) submitted its First and Second 10-Year ISI Program Plan Requests for Relief Nos. RR-01 (Parts 1 and 2), RR-05, RR-11, RR-12 (Parts 1 through 5), and RR-23 for LGS Units 1 and 2.

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

2.1 Request for Relief No. RR-01, Revision 2 (Part 1): Examination Category B-A, item

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Numbers B1.11 and B1.12, Reactor Pressure Vessel (RPV) Shell Welds (Unit 1, First Interval).

l Regulatory Requirement: In accordance with 10 CFR 50.55a(g)(6)(ii)(A), all licensees l must implement once, as part of the inservice inspection interval in effect on September 8,1992, an augmented volumetric examination of the RPV welds specified in item B1.10 of Examination Category B-A of the 1989 Edition of the ASME Code, i Section XI. Examination Category B-A, items B1.11 and B1.12 require volumetric examination of essentially 100% of the RPV circumferential and longitudinal shell welds, as defined by Figures IWB-2500-1 and -2, respectively. Essentially 100%, as defined by j 10 CFR 50.55a(g)(6)(ii)(A)(2), is greater than 90% of the examination volume of each weld, where the reduction in coverage is due to interference by another component or to part geometry. The augmented examination may be used as a substitute for the reactor vessel shell weld examination scheduled for implemenhtion during the ISI interval in effect on September 8,1992.

1 Pursuant to 10 CFR 50.55a(a)(3)(ii), the licensee has proposed an alternative to the I augmented RPV examination coverage requirements because essentially 100%  !

coverage could not be achieved for Unit 1 circumferential shell Weld AD. The licensee  !

stated: j Relief is requested from the First inspection Interval requirements for complete i examination of LGS Unit 1 shell circumferential weld 'AD' for which 87.9%

(736 inches) of the weld length was completely examined while greater than {

2.1% (17.6 inches) of the weld length was only partially examined in accordance l with ASME Code Section XI ISI and Augmented Examination requirements. . . .

Pursuant to 10 CFR 50.55a(a)(3)(i),10 CFR 50.55a(a)(3)(ii), and l 10 CFR 50.55a(g)(6)(ii)(A)(5), PECO Energy considers the following alternate provisions to be practical for the subject weld examinations. PECO Energy j believes that, with the enhan, cements in ultrasonic scanning equipment that  !

PECO %" %s,_ugprerd

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u during the First inspection Interval, ASME Code j

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coverage 5s'riWe achieved with automated u i systems from the reactor pressure vessel outside diameter without the need for supplemental manual examinations. l 1

This percentage is identified in Table RR-01-1 under the Maximum Planned Examination Coverage. However, due to the limited experience with the full l

complement of improved scanners, Table RR-01-1 also identifies the Minimum Expected Examination Coverage percentage that will be achieved.

Evaluation:

To comply with the augmented RPV examination requirements of 10 CFR 50.55a(g)(6)(ii)(A), licensees must volumetrically examine essentially 100% of each of the Item B1.10 shell welds. Essentially 100% is defined as greater than 90% of the

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examination volume of each weld, where the reduction in coverage is due to interference by another component or to part geometry. As an alternative to '

10 CFR 50.55a(g)(6)(ii)(A) for augmented RPV examination, the licensee proposed that the examinations performed be considered to satisfy the augmented reactor vessel examination requirement.

At LGS Unit 1, the RPV examination was performed from the vessel outside diameter using a composite of automated and supplemental manual examination techniques. 1 The licensee was able to obtain essentially 100% examination coverage for all item B1.10 welds except for circumferential Weld AD, which received 87.9% coverage. l Limitations associated with the circumferential weld examination are attributable to interference from adjacent members, including RPV nozzles and integral attachments.

The licensee states that insulation could be removed to gain access to achieve '

essentially 100% coverage on Weld AD. However, the effort required to remove l insulation and perform manual examination in an attempt to increase volumetric I coverage to obtain the remaining 2.1% examination of circumferential Weld AD would result in radiological exposure of approximately 6 man-Rem.

As a result of the augmented volumetric examination rule, licensees must make a reasonable effort to rnaximize examination coverage of their reactor vessels. The licensee has combined automated and manual techniques to maximize coverage. The licensee has examined a significant portion of the subject weld (87.9%). In addition, the licensee has met the coverage requirements for the remaining RPV shell welds on LGS Units 1 and 2. Based on the volumetric examination coverage attained, the staff concludes that any significant patterns of degradation, if present, would have been detected and that the examinations performed provide an acceptable level of quality and safety. Therefore, the licensee's proposed alternative is authorized pursuant to 10 CFR 50.55a(g)(6)(ii)(A)(5) and 10 CFR 50.55a(a)(3)(i) for the first ISI interval for LGS Unit 1.

2.2 Request for Relief No. RR-01, Revision 2 (Part 2): ASME Code,Section XI, Examination Category B-A, items B1.11 and B1.12 require volumetric examination of essentially 100% of the RPV circumferential and longitudinal shell welds, as defined by Figures IWB-2500-1 and -2, respectively, each inspection interval.

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V Licensee's Prooosed Attemative:

Pursuant to 10 CFR 50.55a(a)(3)(i),10 CFR 50.55a(a)(3)(ii) and 10 CFR 50 55a(g)(6)(ii)(A)(5), the licensee considers that the following alternative provides acceptable weld examinations. Complete examination of the subject welds is not -

practical due to the limitations of the nondestructive examination (NDE) instruments and the access restrictions from various reactor vessel appurtenances and containment structures and for personnel occupational dose considerations. The licensee determined that, with the enhancements in ultrasonic scanning equipment that it has supported during the First inspection interval, ASME Code coverage can be achieved with automated ultrasonic testing (UT) systems from the reactor pressure vessel outside diameter without the need for supplemental manual examinations. The actual percent coverage is identified in Table RR-01-1 under the Maximum Planned Examination Coverage. However, due to the limited experience with the full complement of improved scanners, Table RR-01-1 also identifies the Minimum Expected Examination Coverage percentage that will be achieved.

TABLE RR-01-1 l

L"ongitudinal l Wold Length Successive Interval .- _ Successive Interval Wald IDf x - Maximum Planned ?  : Minimum Expected n

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. Examination ~ ' ' Examination

Coverage _-  : Coverage :

BA 137" 100 % 85.8 %

BB 137" 100 % 85.2 %

BC 137" 100 % 72.8 %

BD 137" 100 % 100 %

BE 137" 100 % 100 %

BF 103" 100 % 89.8 %

BG 137" 100 % 81.7 %

BH 137" 100 % 92.5 %

BJ 137" 100 % 96.4 %

BK 86" 100% 51.3 %

BM 86" 100 % 50.0 %

l BN 92.8" 100% 76.5 %

BP 92.8" 100 % 98.8 %

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Licensee's Basis for Proposed Alternative:

, j The Code requires that Examination Category B-A, item B1.11 circumferential shell .

welds and item B1.12 longitudinal shell welds receive 100% volumetric examination 1 each inspection interval. The licensee is proposing to examine " essentially 100%" of the longitudinal (axial) welds and 2-3% of the circumferential shell welds (at the intersection of the axial welds) for the remainder of the operating life of the plants. This position is supported by the report, "BWR Vessel and Internals Project, BWR Reactor Pressure Vessel Shell Weld Inspection Recommendations, BWRVIP-05," dated September, _

1905, and the NRC Safety Evaluation Report (SER)," Evaluation by the Office of Nuclear Reactor Regulation Related to the Review of the Topical Report by the Boiling Water Reactor Vessel and Internals Project: BWR Reactor Pressure Vessel Shell Weld Inspection Recommendations, BWRVIP-05," dated July 28,1998. The licensee's position is also in accordance with the guidanca promulgated in NRC Generic Letter (GL) 98-05 " Boiling Water Reactor [BWR] Licensees Use of the BWRVIP-05 Report to Request Relief from Augmented Examination Requirements on Reactor Pressure Vessel Circumferential Shell Welds," dated November 10,1998.

The licensee has requested that this proposal be authorized for the remaining operating life of the facilities, j

Evaluation:

Based on the NRC's assessment of BWRVIP-05 and the guidance promulgated in GL 98-05, the licensee's proposed alternative to discontinue examining the Category B-A, item B1.11, circumferential welds provides an acceptable level of quality and safety I and is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the remaining ISI intervals in the current licensing period for both units.

2.3 Request for Relief No. RR-05, Revision 2: ASME Code,Section XI, Examination Category C-C, requires a surface examination of 100% of selected areas of each welded attachment to vessels, piping, pumps, and valves each inspection interval, in the case of multiple vessels, only the integrally welded attachments of one vesselin a group of vessels of similar design and service (or the equivalent of one vessel) need be examined.

Pursuant to 10 CFR 50.55a(a)(3), the licensee proposed to perform the required surface examinations of Class 2 integral attachment welds in accordance with ASME Section XI, 1995 Edition with the 1996 Addenda, Table IWC-2500-1, Examination Category C-C. In addition, the licensee plans to implement the requirements of the 1995 Edition with the 1996 Addenda of the ASME Code in conjunction with all related regulations for its applicable relief requests which are related to its submittals.

Licensee's Basis for Proposed Alternative (as stated): i Access for examination equipment is limited by component configuration or installed support members. 4-l

l During the First inspection Interval, attempts to perform alternate NDE methods, l

e.g., Liquid Penetrate (PT) or Ultrasonic Testing (UT) Class 2 integral

, attachment welds proved unsuccessful. Neither NDE method resulted in an increase in examination coverage (in fact UT resulted in less coverage), in addition, there was a significant increase in radiation exposure to both examination and support personnel due to the weld surface preparation requirements and increased examination times associated with these methods.

Also, installed support members caused the same access limitations regardless l of the NDE method used.

All welds were examined to the maximum extent practical. Increased examination coverage is not possible without undue hardship, such as a plant modification.

The 1995 Edition of ASME Section XI hos recognized these generic access limitations and has appropriately modified the Examination Requirements. Table IWC-2500-1, Examination Category C-C, has also included Note (6) which requires examination of the integral attachment welds whenever component support member deformation is identified.

Adoption of PECO Energy's proposed alternative will result in a reduction in radiation exposure to examination and support personnel and will reduce the number of welds requiring relief requests due to incomplete examination coverage based solely on the requirements of the 1986 Edition of the ASME Section XI Code. These alternative rules are based on the 1995 Edition of the Code, and as such, provide an acceptable level of quality and safety which does not compromise the adequacy of the LGS Units 1 and 2 ASME Section XI Programs in meeting the intent of the ASME Code.

Evaluation:

The licensee's current Code of record is the 1986 Edition of Section XI.Section XI, Table IWC-2500-1, Examination Category C-C, requires that required areas of each weld 9d attachment to vessels, piping, pumps, and valves receive a 100% surface examination. In the case of multiple vessels of similar design and service, the licensee has the option of performing all of these examinations on one vessel or distributing the examinations among the vessels. The licensee proposed to use specific sections of the 1995 Edition through the 1996 Addenda of the Code as an alternative to thM Edition,Section XI, Table IWC-2500-1, Examination Category C-C.

The 1995 Edition through the 1996 Addenda of ASME Code,Section XI, recognizes generic access limitations and has modified the Examination Requirements for Category C-C integral attachments. The 1995 Edition through the 1996 Addenda ASME Code examination coverage for Class 2 integral attachments has been redefined as essentially 100% of the length of the attachment weld subject to examination. In addition, the 1995 Edition through the 1996 Addenda has the identical surface

! examination method as the 1986 Edition. In addition, IWC-2500- Figure 5, in the 1995 Addenda precludes the requirement for disassembly of the supports (e.g., pipe clamps,.... and pipe support members).

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• d in addition, the later Edition of the Code with Addenda recognizes the Code change in

, Table IWC-2500-1, Examination Category C-C, because it includes Note (6) that l requires additional examinations of the integral attachment welds when component

! support member deformation is identified. The staff determined that the surface examinations will ident;fy any surface degradation and that Note (6) requiring additional examinations of the integral attachment welds when component support member deformation is identified provides reasonable assurance of structuralintegrity of the subject components.

Access for examination equipment is limited by configuration or installed support members. The licensee's attempts to perform alternative NDE proved to be unsuccessful. The NDE methods employed did not result in an increase in examination coverage. In fact it resulted in less coverage, in addition, the licensee experienced a i

significant radiation exposure to both examination and support personnel. The licensee noted that all welds were examined to the maximum extent practical. The licensee found that increased examination coverage was not possible without undue hardship, e.g., disassembly of the supports, the installation of temporary supports, or increased radiation exposure to personnel.

The staff determined that the 1986 Edition Codo requirements are a hardship on the licensee without a compensating increase in quality and safety. The licensee's proposed alternative to use the ASME Section XI,1995 Edition through the 1996 i Addenda, Table IWC-2500-1, Examination Category C-C, provides reasonable l assurance of structuralintegrity of the subject components. Therefore, the licensee's proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) for the first and ,

second ISI intervals for both units. i 2.4 Request for Relief No. RR-11, Revision 1: The 1986 ASME Code Edition,Section XI, (

Examination Categories B-H and B-K-1, require 100% volumetric or surface l examination, as applicable, for each attachment weld subject to examination.

Examinations shall be performed during the first and second inspection intervals for licensees using Inspection Program B.

Pursuant to 10 CFR 50.55a(a)(3), for Class 1 systems, the licensee proposed to perform the required examinations in accordance with ASME Section XI,1995 Edition through the 1996 Addenda, Table IWB-25001, Examination Category B-K as supplemented by Code Case N-323-1," Alternative Examination For Welded Attachments to Pressure Vessels," for Figure Nos. lWB-2500-13 and IWB-2500-14. As required by Table IWB-2500-1, Examination Category B-K, Note (6), additional examinations of the integral attachment welds shall be performed when component support deformation is identified.

L_icense9's Basis for Proposed Alternative (as stated):

Access to the reactor pressure vessel stabilizer bracket attachment welds is limited due to mirror insulation support rpembers affixed to the stabilizer bracket lugs and the stabilizer assembly support r6 embers. These support members

. . j preclude equipment access necessary for complete magnetic particle examination of the weld and required area.

Access for examination equipment is also limited in the area of skirt attachment weld build-up. The configuration of the HPV skirt knuckle to the bottom head limits access for complete examination of the underside of the weld.

Access for examination of Class 1 piping integral attachment welds is limited due to installed support members.

During the First inspection interval, attempts to perform both Liquid Penetrate (PT) and Ultrasonic Testing (UT) of the reactor pressure vesselintegral attachment welds proved unsuccessful. Neither NDE method resulted in an increase in examination coverage (in fact UT resulted in less coverage). Also, there was a significant increase in radiation exposure to both examination and support personnel due to the weld surface preparation requirements and increased examination times associated with these methods.

In the case of the piping integral attachment welds, the installed support members caused the same access limitations regardless of the NDE method used.

The 1995 Edition of ASME Section XI (and Code Case N-323-1) has recognized these generic access limitations and have appropriately modified the Examination Requirements. Table IWB-2500-1, Examination Category B-K, has also included Note (6) which requires examination of the integral attachment welds whenever component support member deformation is identified.

Adoption of PECO Energy's proposed alternative will result in a reduction in radiation exposure to examination and support personnel and will reduce the number of welds requiring relief requests due to incomplete examination coverage based solely on the requirements of the 1986 Edition of the ASME Section XI Code. These alternative rules are based on the 1995 Edition of the Code, and as such, provide an acceptable level of quality and safety which does not compromise the adequacy of the LGS Units 1 and 2 ASME Section XI Programs in meeting the intent of the ASME Code.

Evaluation:

The 1995 Edition with the 1996 Addendum of ASME Section XI, requires examination coverage of Class 1 integral attachment welds to include essentially 100% of the length of the attachment weld at each attachment subject to examination. The 1995 Edition with the 1996 Addendum has combined Categories B-H and B-K-1 from the 1986 Edition to one Category B-K. In addition, the 1995 Edition through the 1996 Addenda eliminated the licensee's examination method option of whether to perform a surface or a volumetric exam. The later Code Editions have revised the examination method to a surface examination only. In addition, IWB-2500-Figure-15 of the 1995 Addenda revision precludes the requirement for disassembly of the supports (e.g., pipe clamps,...

and support members). Furthermore, in recognition of the Code change, Table l

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9 IWB-2500-1, Examination Categories B-K, includes Note (6) which requires additional examinations of the integral attachment welds when component support member deformation is identified.

The majority of the integral attachment welds to piping are partial penetration welds, and a surface examination is the appropriate method of examination for these welds. The surface examination for full penetration welds, which are in the minority, will detect abnormal surface conditions. The combination of the proposed surface exams and Table IWB-2500-1, Examination Category B-K Note (6) requiring auditional examinations of the integral attachment welds when component support member  !

deformation is identified provides reasonable assurance of structuralintegrity of the subject components.

The licensee is also requesting the use of Code Case N-323-1, " Alternative Examination For Welded Attachments to Pressure Vessels," for Figure Nos.

lWB-2500-13 and IWB 2500-14 as an alternative to the Code requirements. Code Case N 3231, provides an alternative to the requirements of Examination Category B-K of the 1995 Addenda or Examination Category B-H from the Winter 1981 Addenda, through the 1995 Edition when the welds can be inspected from one side. Examinations are performed for welded attachments to pressure vessels as shown in Figures 1 & 2' when only one side of the attachment weld is accessible for examination. Code Case N-323-1 requires that:

a. for the configuration shown in Figures 1 and 2 a surface examination from the accessible side of the attachment weld may be performed or;

b. for the configuration shown if Figure 2, a volumetric examination of Volume A-B and C-D from the accessible side of the attachment may be performed.

For Category B-H welds contained in the 1986 Code Edition, the licensee noted that the examination of the reactor pressure vessel stabilizer bracket attachment weld is limited due to mirror insulation support members affixed to the stabilizer bracket lugs and the stabilizer assembly support members. The support members precluded equipment access necessary for complete magnetic particle examination of the weld and required area. Access for the RPV skirt knuckle to the bottom head limits access for complete examination of the underside of the weld.

For the Category B-K 1 contained in the 1986 Code Edition, the licensee noted that access for examination is limited due to installed support members. Access for examination of equipment is limited by configuration or installed support members. The licensee's attempts to perform alternative NDE proved to be unsuccessful. The licensee noted that NDE methods employed did not result in an increase in examination coverage. In fact for UT, it resulted in less coverage in addition, the licensee experienced a significant radiation exposure to both examination and support personnel.

The licensee noted that all welds were examined to the maximum extent practical. The

. licensee found that increased examination coverage was not possible without undue

' Figures 1 & 2 are contained in ASME Code Case N 323-1 and are not included in this SE.

e hardship, e.g., disassembly of the supports, the installation of temporary supports, and increased radiation exposure to personnel.

Code Case N-323-1 provides alternative areas for the licensee to examine welded attachments to pressure vessels when only one side of the attachment weld is accessible for examination. To meet the Code requirements, the licensee would have to redesign the welded attachments. The Code requirements would be a hardship and burden on the licensee without a compensating increase in quality and safety. The staff concluded that Code Case N 323-1 provides a reasonable alternative to Code requirements and provides reasonable assurance of structuralintegrity of the subject components.

The staff has determined that for the Category B-H and B-K-1 welds the Code requirements would be a hardship without a compensating increase in quality and safety. The licensee's proposed alternative to perform the required examinations in accordance with the ASME Section XI,1995 Edition through the 1996 Addenda, Table IWB-2500-1, Examination Category B-K, as supplemented by Code Case N-323-1 for Figure Nos. lWB-2500-13 and IWB-2500-14, provides reasonable assurance of structuralintegrity of the subject components. Therefore, the licensee's proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) for the first and second ISI l intervals for both units.

2.5 Request for Relief No. RR-12 (Part 1): ASME Code Section XI, Paragraph IWA-4400,

" Pressure Test," requires a system hydrostatic test in accordance with IWA-5000 after q

l repairs by welding on the pressure-retaining boundary. I The licensee proposed to use Code Case N-416-1," Alternative Pressure Test Requirements for Welded Repairs or Installation of Replacement items by Welding, l Class 1,2 and 3,Section XI, Division 1."

l in its March 11,1999, iciter. the licensee clarified that:

The alternate provisions of ASME Section XI Code Case N-416-1, Alternative Pressure Test Requirements for Welded Repairs or installation of Replacement l l Items by Welding, Class 1,2 and 3 would be used to perform pressure testing i i

associated with ASME Section XI Repairs and Replacements as follows: I NDE shall be performed in accordance with the methods and acceptance criteria of the applicable Subsection of the 1992 Edition of ASME Section 111.

When performing repairs by welding, or the installation of replacement

" " wahhgespra the pressure retaining boundary of Class 3 coidporients, an additional surface examination (Magnetic Particle (MT) or [ Liquid Penetrant Test) (PT)) shall be performed on the root pass layer of butt and socket welded joints when surf ace examination is required for the final weld by the 1992 Edition of ASME Section Ill. For those Class 3 welds receiving radiography in lieu of a surface examination in

accordance with ASME Section ill, no additional surface examination of the root layer needs to be performed. This provision does not apply to Class 1 and 2 components, since these components have an ongoing requirement for surface and volumetric examinations as part of the ASME Section XI Inservice !nspection Program.

Prior to or immediately upon return to service, a visual examination (VT-2) shall be performed in conjunction with a system leakage test, using the 1992 Edition of ASME Section XI,in accordance with paragraph IWA-5000, at normal operating pressure and temperature.

Use of ASME Code Case N-416-1 shall be documented on a Form NIS-2, Owner's Report for Repairs or Replacements or approved alternative, when required.

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

Elevated pressure hydrostatic tests are difficult to perform and often represent a true hardship. Some of the difficulties associated with elevated pressure testing include the following: {!

Hydrostatic testing often requires complicated or abnormal valve line-ups in '

order to properly vent, fill, and isolate the cotoponent requiring testing.

Relief valves with'setpoints lower than the hydrostatic test pressure must be gagged, or removed and blind flanged. The removal and flanging process requires the draining and refilling of the system.

Valves that are not normally used for Isolation (normally open pump discharge valves), require time consuming seat maintenance in order to allow for pressurization.

The radiation exposure required to perform a hydrostatic pressure test is high due to the large amount of time required to prepare the system for testing (install l relief valve gags, perform appropriate valve line-ups, etc.).

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The difficulties encountered in performing a hydrostatic pressure test are prohibitive when weighed against the benefits. Industry experience shows that most through wall leakage is detected during systern operation as opposed to I during elevated pressure tests such as 10-year hydrostatic tests.

Little benefit is gained from the added challenge to the piping system provided by an elevated pressure test, when compared to an operational test, especially when one considers that the piping stress experienced during a hydrostatic test i

does not include the significant stresses associated with the thermal growth and dynamic loading associated with design basis.

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Evaluation Section XI of the Code requires a system hydrostatic test to be performed in accordance with IWA-5000 after repairs made by welding on the pressure-retaining boundary. The licensee has proposed to use Code Case N-416-1 in lieu of the Code. Code Case -

N-416-1 specifies that NDE of the welds be performed in accordance with the applicable subsection of the 1992 Edition of ASME Code, Section lil; a VT-2 visual examination will be performed at nominal operating pressure and temperature in conjunction with a ,

system leakage test, in accordance with Paragraph IWA-5000 of the 1992 Edition of I Section XI; and that use of the Code Case be documented on an NIS-2 Form.

The 1989 Edition of Sections XI and 111 is the latest edition referenced in 10 CFR  !

50.55a. The staff has compared the system pressure test requirements of the 1992 )

Edition of Section XI to the requirements of IWA-5000 of the 1989 Edition of Section XI.

In summary, the 1992 Edition imposes a more uniform set of system pressure test ]

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requirements for Code Class 1,2, and 3 systems. The terminology associated with the j system pressure test requirements for all three code classes has been clarified and I streamlined. The test frequency and test pressure conditions associated with these I tests have not been changed. The hold times for these tests have either remair;ed unchanged or increased. The corrective actions with respect to removal of bolts from leaking bolted connections have been relaxed in the 1992 Edition, and this relaxation )

j has been accepted by the staff in previous safety evaluations. The post-welded repair NDE requirements of the 1992 Edition of Section lli remain the same as the requirements of the 1989 Edition of Section 111. Therefore, the staff finds this aspecf of Code Case N-4161 to be acceptable. '

Hardships are generally encountered with the performance of hydrostatic tesung performed in accordance with the Code. For example, since hydrostatic test pressure would be higher than nominal operating pressure, hydrostatic pressure testing frequently requires significant effort to set up and perform. The need to use special equipment, such as a temporary attachment of test pumps and gauges, and the need for individual valve lineups can cause the testing to be on the critical path.

Piping components are designed for a number of loadings that would be postulated to occur under the various modes of plant operation. Hydrostatic testing only subjects the niping components to a small increase in pressure over the design pressure and, l therefore, does not present a significant challenge to pressute boundary integrity. i Accordingly, hydrostatic pressure testing is primarily regarded as a means to enhance ,

leakage detection during the examination of components under pressure, rather than l

solely as a measure to determine the structuralintegrity of the components.  !

The industry experience has demonstrated that leaks are not being discovered as a result of hydrostatic test pressures propagating a preexisting flaw through wall. This l experience indicates that leaks in most cases are being found when the system is at normal operating pressure. This is largely due to the fact that hydrostatic pressure testing is required only upon installation and then once every 10-year inspection interval, while system leakage tests at nominal operating pressures are conducted a minimum of l once each refueling outage for Class 1 systems and once each 40-m6 nth inspection  ;

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, period for Class 2 and 3 systems. In addition, leaks may be identified by plant operators during system walkdowns which may be conducted as often as once a shift.

Following the performance of welding, the code requires volumetric examination of repairs or replacements in Code Class 1 and 2, but would also allow only a surface examination of the final weld pass in Code Class 3 piping components. There are no ongoing NDE requirements for Code Class 3 components except for visual examination for leaks in conjunction with the 10-year hydrostatic tests and the periodic pressure tests.

Considering the NDE performed on Code Class 1 and 2 systems and considering that the hydrostatic pressure tests rarely result in pressure boundary leaks that would not occur during system leakage tests, the staff believes that increased assurance of the integrity of Class 1 and 2 welds is not commensurate with the burden of performing hydrostatic testing. However, considering the nature of NDE requirements for Code Class 3 components, the staff does not believe that elimination of the hydrostatic pressure testing while only performing system pressure testing is an acceptable alternative to hydrostatic testing unless additional surface examinations are performed on the root pass layer of butt and socket welds on the pressure retaining boundary of Class 3 components when the surface examination method is used in accordance with Section Ill.

For clarification, it should be noted that, consistent with the Code Case requiring performance of NDE in acccrdance with the methods and acceptance criteria of the 1992 Edition of Section lil, the scope of exarnination should also be in accordance with the 1992 Edition of Section Ill. The additional surface examination of the root layer of Class 3 pressure retaining welds should be performed only when those pressure retaining welds are required to have a surface examination performed in accordance with the 1992 Edition of Section Ill. For those Class 3 welds receiving radiography in lieu of a surface examination in accordance with Section Ill, no additional surface examination of the root layer needs to be performed.

The staff concludes that the licensee's proposed alternative to use Code Case N-416-1 and its additional alternative to perform an additional surface examination on Class 3 root pass layer of butt and socket joints when surface examination is required for the final weld by the 1992 Edition of ASME, Section lil, provides an acceptable level of quality and safety. Therefore, the licensee's proposed alternative to use Code Case N-416-1 is authorized pursuant to 10 CFR 50.55a(a)(3)(i). Use of Code Case N-416-1, is authorized for the first and second ISI intervals for both units.

2.6 Request for Relief No. RR-12 (Part 2): ASME Code,Section XI, Table IWB-2500-1, Examination Category B-P, Table IWC-2500-1, Examination Category C-H, and Table IWD-2500-1, Examination Categories D-A, D-B and D-C, require system hydrostatic

testing of pressure-retaining componen9 in accordance with IWA-5000 once each ISI interval.

v L

Pursuant to 10 CFR 50.55a(a)(3)(ii), the licensee has requested authorization to use Code Case N-498-1, " Alternate Rules for 10-Year Hydrostatic Pressure Testing for Class 1,2, and 3 Systems,Section XI, Division 1."

Licensee's Basis for Procosed Alternative (as stated):

Adoption of Code Case N-498-1 will eliminate the need for the performance of the Class 1,2, and 3 once per inspection Interval Hydrostatic Test at multiples of the system design pressure, as required by ASME Boiler and Pressure Vessel (B&PV) Code,Section XI, thereby, reducing the amount of personnel radiation exposure received during the performance of the Class 1,2, and 3 hydrostatic test.

Code Case N-498-1 represents technically acceptable alternative rules to ASME Section XI Code requirements. The fact that this Code Case has not been endorsed in the Regulatory Guide in no way detracts from its technical adequacy since the major reason for its omission is the timing of its publication with respect to the most recent revision of the Regulatory Guide. That is, the subject Code Case is relatively recent and it is expected that it will be accepted in a subsequent revision of the Regulatory Guide.

Adoption of this alternative rule provides an acceptable level of quality and safety and does not compromise the adequacy of the LGS ASME Section XI Programs in meeting the intent of the ASME Code.

Evaluation The Code requires a system hydrostatic test once per 10-year interval in accordance with the requirements of IWA-5000 for Class 1,2, and 3 pressure-retaining systems. In lieu of the Code-required hydrostatic testing requirements, the licensee has requested authorization to use Code Case N-498-1, " Alternative Rules for 10-Year System Hydrostatic Testing for Class 1,2, and 3 Systems," dated May 11,1994. The licensee noted that prior to performing a VT-2 visual examination, the system will be pressurized to nominal opentting pressure for at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for insulated systems and 10 minutes for non-insulateo' <;ystems. In addition, the system will be maintained at normal operating pressure during performance of the VT-2 visual examiwkn.

Information prepared in conjunction with ASME Code Case N-498-1 notes tM3tTf"-

system hydrostatic test is not solely a test of the structuralintegrity of the system but also provides a means N enhance leakage detection. That this was the original intent is indicated in a paper by S. H. Bush and R. R. Maccary, ' Development of in-Service inspection Safety Philoscphy fer U.S.A. Nuclear Power Plants," ASME,1971. Piping

! components are designed for a number of loadings that would be postulated to occur under the various modes ut plant operation. Hydrostatic testing only subjects the piping components to a small increase in pressure over the design pressure and therefore does not present a significant challenge to pressure boundary integrity since piping dead weight, thermal expansion, and seismic loads, which may present far greater l

challenge to the structuralintegrity of a system than fluid pressure, are not part of the loading imposed during a hydrostatic test. Water is used as a test medium in the L

hydrostatic test. Because water is highly incompressible, any small leak from a high pressurized water solid system can be readily detected by a sharp decline in system pressure, or by continual pumping required to maintain the system pressure. As such, hydrostatic pressure testing is primarily regarded as a means to enhance leakage detection during the examination of components under pressure since such a test provides good indication of any system leakages, especially those that might originate from small through-wall cracks of the pressure boundary. Consequently, this in-service hydrostatic pressure test required by the Code enhances the possibility of timely discovery of small through-wall flaws which, because of a tiny leak size, might not be readily detected by any other means such as system walkdowns or installed leak-detection systems.

The licensee requested approval for the implementation of the alternative rules of ASME Section XI, Code Case N-498-1, dated May 11,1994, " Alternative Rules for 10-Year System Hydrostatic Testing for Class 1,2, and 3 Systems," in lieu of 10-year hydrostatic testing of Class 1,2, and 3 systems. The licensee may already use N-498, " Alternative Rules for 10-Year System Hydrostatic Testing for Class 1, and 2 Systems," since use of Code Case N-498 for Class 1 and 2 systems is approved by the NRC in RG 1.147, Rev.11. The rules for Code Class 1 and 2 in N 498-1 are unchanged from those in N-498. The staff found N-498 acceptable because the alternative of performing a test at a system pressure that is slightly lower than the hydrostatic pressure provided adequate assurance ol leakage integrity and because compliance with the specified requirements would result in hardship without a compensating increase in the level of quality and safety.

Code Case N-498-1 was revised from N-498 to encompass Class 3 components and specifies requirements for Class 3 that are identical to those for Class 2 components. In lieu of 10-year hydrostatic pressure testing at or near the end of the 10-year interval, Code Case N-498-1 requires a visual examination (VT-2) be performed in conjunction with a system leakage test in accordance with paragraph IWA-5000. A system leakage j test may be conducted to demonstrate that leaks from pressure boundary that may originate from through-wall flaws do not exist. This would meet the intent of the hydrostatic test as noted above.

Currently, licensees expend considerable time, radiation dose, and dollar resources carrying out hydrostatic test requirements. A significant amount of effort may be necessary (depending on system, plant configuration, Code class, etc.) to temporarily remove or disable code safety and/or relief valves to meet test pressure requirements.

The safety assurance provided by the enhanced leakage detection gained from a slight increase in system pressure during a hydrostatic test are offset or negated by the following factors: having to gag or remove code safety and/or relief valves, placing the system in an off-normal state, eiecting temporary supports on steam lines, possible .

extension of refueling outages, and resource requirements to set up testing with special I equipment and gages. 1 Class 3 systems do not normally receive the ampunt or type of NDEs that Class 1 and 2 systems receive. While Class 1 and 2 system faildres are relatively uncommon, Class 3 system leaks occur more frequently and the failure mode typically differs. Based on a review of Class 3 system failures requiring repair for the last 5 years in Licensee Event I l

i

E, .

l Reports and the Nuclear Plant Reliability Data System databases, the most common causes of failures are erosion-corrosion (EC), microbiologically induced corrosion (MIC),

and general corrosion. Licensees generally have programs in place for prevention, detection, and evaluation of EC and MIC. Leakage from general corrosion is readily apparent to inspectors when performing a VT-2 examination during system pressure tests.

Giving consideration to the minimal amount of increased assurance provided by the increased pressure associated with a hydrostatic test versus the pressure for the system leakage test and the hardship associated with performing the ASME Code required hydrostatic test, the staff finds that compliance with the Section XI hydrostatic testing requirements results in hardship for the licensees without a compensating increase in the level of quality and safety. Accordingly, the licensee's proposed alternative to use Code Case N-498-1 is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) for the first and second ISI intervals for both units.

2.7 Request for Relief No. RR-12 (Part 3): The NRC staff had previously reviewed this Request for Relief and authorized the actions in accordance with the request for the first ISI interval for LGS Unit 1. This authorization was documented in an NRC Safety Evaluation dated October 9,1997. The licensee requested that the previously approved authorization to implement the alternatives contained in Code Case N-546, " Alternative Requirement for Qualifications of VT-2 Visual Examination Personnel," be extended to the second ISI interval for LGS Units 1 and 2. There are no technical changes in the licensee's relief request and, therefore, the NRC staff concludes that its findings as stated in the October 9,1997, staff evaluation remain valid. The proposed alternative continues to provide an acceptable level of quality and safety and is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the second ISI interval for LGS Units 1 and 2.

2.8 Request for Relief No. RR-12 (Part 4): ASME Code,Section XI, Examination Category B-J requires 100% volumetric and/or surface examination of longitudinal piping welds as defined by Figure IWB-2500-8. The examination shall include at least one pipe diameter, but not more than 12 inches, of each longitudinal weld intersecting circumferential welds required to be examined by Examination Categories B-J and B-F.

Examination Categories C-F-1 and C-F-2 require 100% volumetric and/or surface examination, as defined by Figure IWC-2500-7, -12, and -13, for 2.5t [ pipe wall thickness) of each longitudinal weld intersecting circumferential welds examined. ,

i Licensee's Basis for Proposed Alternative:

Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed to use Code Case N-524,

" Alternative Examination Requirements for Longitudinal Welds in Class 1 and 2 Piping, l Section XI, Division 1," as an alternative to the Code requirements. l ASME Section XI requires the examination of one pipe diameter, but not more than 12 inches, of Class 1 longitudinal piping welds. For Class 2 piping welds, the length of longitudinal weld required to be examined is 2.5 times the pipe thickness. These lengths are measured from the intersection with the circumferential weld. The licensee's proposed alternative is to examine only the portions of longitudinal welds within the j

examination area of the intersecting circumferential weld in accordance with Code Case N-524," Alternative Examination Requirements for Longitudinal Welds in Class 1 and Class 2 Piping."

Evaluation Longitudinal welds are produced during the manufacture of the piping, not in the field as are circumferential welds. Consequently, longitudinal welds are fabricated under strict manufacturing standards, which provide assurance of structuralintegrity. These welds have also been subjected to preservice and initial inservice examinations, which provide additional assurance of structural integrity. No significant loading conditions or material degradation mechanisms have been identified to date that specifically relate to longitudinal seam welds in nuclear plant piping. The most critical region of the longitudinal weld is the portion that intersects the circumferential weld. Since this region will be examined during the examination of the circumferential weld, the licensee's alternative provides an acceptable level of quality and safety. Therefore, the licensee's proposed alternative, to use Code Case N-524, is authorized pursuant to 10 CFR j 50.55a(a)(3)(i) for the first and second ISI intervals for both units.

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2.9 Request for Relief No. RR-12 (Part 5): ASME Code,Section XI, IWA-5250(a)(2),

requires that if leakage occurs at a bolted connection, the bolting shall be removed, j VT-3 visually examined for corrosion, and evaluated in accordance with IWA-3100. I I

Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed as an alternative to the requirements of IWA-5250(a)(2) to perform a six-step engineering evaluation before removing bolting and to perform a VT-1 examination (in lieu of a VT-3 examination) when required. The licensee stated:

When leakage is identified at Class 1,2, or 3 bolted connections by VT-2 visual examination during system pressure testing, an evaluation will be performed to determine the susceptibility of the bolting to corrosion and assess the potential for failure. The evaluation will, at a minimum, consider the following factors:

1. Bolting materials l

2. Corrosiveness of process fluid leaking l

3. Leakage location l

4. Leakage history at connection or other system components

5. Visual evidence of corrosion at connection (while connection is assembled)  :

6. Service age of bolting materials i Licensee's Basis for the Proposed Alternative (as stated):

Removal of pressure retaining bolting at mechanical connections for visual, VT-3 examination and subsequent evaluation, in locations where leakage has been identified, is not always the most discerning course of action to determine the acceptability of the botting. The Code requirement to remove, examine, and

evaluate botting in this situation does not allow PECO Energy to consider other factors which may indicate the acceptability of mechanical joint bolting.

Other factors which should be considered when evaluating bolting acceptability when leakage has been identified at a mechanical joint include, but are not limited to: joint botting material, service age of joint bolting materials, location of the leakage, history of leakage at the joint, evidence of corrosion with the joint assembled, and corrosiveness of process fluid.

If any of the factors used for the evaluation indicates a potential for the bolting to corrode, then the most susceptible bolting will be removed and VT-1 (not VT-3) exam'ned for corrosion and evaluated in accordance with IWB-3517. When the removed bolt has evidence of degradation, additional bolting in the connection will be removed in accordance with IWB-2430, receive a VT-1 examination, and an evaluation in accordance with IWB-3517. If the results of the engineering evaluation indicate that bolting degradation is not expected, bolting need not be removed.

Performance of the pressure test while the system is in service may identify leakage at a bolted connection that, upon evaluation, may conclude the integrity and pressure retaining ability of the joint is not challenged. It would not be prudent to negatively impact the availability of a safety system by removing the system from service to address a leak that does not challenge the system's ability to perform its safety function.

Adoption of this alternative rule provides an acceptable level of quality and safety and does not compromise the adequacy of the LGS ASME Section XI Programs in meeting the intent of the ASME Code.

NRC Staff's Request for Additionalinformation l

In a letter dated February 9,1999, the NRC staff requested additionalinformation from l PECO Energy to further clarify the basis for PECO Energy's request for relief. I Specifically, the NRC staff requested that PECO Energy provide an answer on the following.

When the pressure test is performed on a system that is in service or that Technical Specifications require to be operable, and the bolting is susceptible to corrosion, the evaluation shall address the connection's structural integrity until the next component / system outage of sufficient duration. If the evaluation concludes the system can perform its safety-related function, removal of the bolt closest to the source of the leakage and a VT 3 visual examination of the bolt will be perfymM whengem or component is taken out of service for a sufficient d'uTaTo'n (to accomplish other system maintenance activities).

lWA-3100 invokes the use of Articles IWB-3000, IWC-3000, and IWD-3000 for j Class 1,2, and 3 pressure-retaining components, respectively. None of the subparagraphs in these articles provide acceptance criteria for the VT-3 visual examinations. In order for this relief request to be considered acceptable, the acceptance criteria must be specified by the licensee. The staff determined that

9 it is technically prudent to implement a VT-1 visual examination using the acceptance criteria defined in lWB-3000 for bolting removed for visual examination. Alternatively, a VT-3 visual examination using the IWB-3000, VT-1 acceptance criteria, is also considered acceptable. Moreover, describe how the proposed alternative provides an acceptable level of quality and safety at LGS, Units 1 and 2.

Licensee's Response in its letter dated April 15,1999, PECO Energy replied to the NRC's Request for Additional Information by stating that, pursuant to 10 CFR 50.55a(a)(3)(ii), PECO Energy requests approval tc conduct an engineering evaluation of allleaking connectioris to determine whether any bolting requires removal and inspection, as an alternative to the corrective measure requirements of IWA-5250(a)(2). Further, PECO Energy proposes to apply the Class 1 requirements of IWB-3142.4, including the requirement for subsequent examinations on an increased frequency per IWB-2420(b) and (c) to bolting in Class 1,2, and 3 components when acceptance of a relevant condition for continued service is based on analytical evaluation. When the evaluation determines that bolting in Class 1,2, and 3 components needs to be removed to determine if the condition is relevant, PECO Energy shall perform a VT-1 visual examination using the acceptance criteria defined in ASME Section XI, IWB-3517, Standards for Examination Category B-G-1, Pressure Retaining Bolting Greater Than 2 inch in Diameter, and Examination Category B-G-2, Pressure Retaining Botting 2 Inch and Less in Diameter for the bolting removed for visual examination.

Removal of pressure retaining botting at mechanical connections for visual, VT-3 examination and subsequent evaluation, in locations where leakage has been identified, l is not always the most discerning course of action to determine the acceptability of the bolting. The Code requirement to remove, examine, and evaluate botting in this situation does not allow PECO Energy to consider other factors which may indicate the acceptability of mechanical joint bolting.

Other factors which should be considered when evaluating bolting acceptability when .J leakage has been identified at a mechanical joint include, but are not limited to: joint bolting material, service age of joint botting materials, location of the leakage, history of leakage at the joint, avHence of corrosion with the joint assembled, and corrosiveness of process fluid.

If any of the factors used for the evaluation indicates a potential for degradation of the bolting due to corrosion, then the most susceptible bolting will be removed and VT-1 (not VT-3) examined for corrosion, and evaluated in accordance with IWB-3517. When the removed bolt has evidence of degradation, additional bolting in the connection will be removed in accordance with IWB-2430, receive a VT-1 examination, and an l evaluation in accordance with IWB-3517. If the results of the engineering evaluation '

indicate that bolting degradation is not expected, bolting need not ce removed. l Performance of the pressure test while the system is in service may identify leakage at a bolted connection that, upon evaluation, may verify that the integrity and pressure ,

retaining ability of the joint is not challenged. It would not be prudent to negatively l l

L. ,  !

impact the availability of a safety system by removing the system from service to address a leak that does not challenge the system's ability to perform its safety function.

Further, if evidence exists which indicates that the leakage found is not a preexisting condition and the leakage is stopped, the concern for corrosion of the bolting materialis -

reduced. The cost and added radiation exposure associated with the requirement to disassemble and examine the bolting, along with the inherent need to repeat all or j portions of the associated pressure test and the potential impact on plant operations, far i outweigh the increase in safety resulting from performance of this examination.

The objective of the ASME Code requirement is to detect degradation of the fastener that has resulted in leakage of the joint. The ASME Code is not attempting to address alignment and gasket problems associated with a leaking flange connection. The required examination method is VT-3, which is conducted to determine the general mechanical and structural condition of components and their supports by verifying parameters such as clearances, settings, and physical displacements; and to detect discontinuities and imperfections, such as loss of integrity at bolted or welded connections, loose or missing parts, debris, corrosion, wear, or erosion.

The ASME Code (1990 Addenda and later Editions) accepts a sarnple of bolts, with a provision for sample expansion, instead of a visual examination of all bolts after the detection of leakage. The current revision of the Code was published after due consideration of the acceptance standards for the number of degraded bolts that could be present before a significant safety problem would exist.

PECO Energy's proposal to perform a VT-1 examination instead of a VT-3 examination when bolting is removed and to apply Class 1 requirements for acceptance criteria, subsequent examinations, and additional examinations when evaluating leakage at bolted connections in Class 1,2, and 3 components meets or exceeds the requirements of the ASME Section XI Code. The examination method is superior to the ASME Section XI Code requirement. -

Adoption of this Code requirement provides an acceptable level of quality and safety and does not compromise the adequacy of the LGS ASME Section XI Programs in meeting the intent of the ASME Code.

Evaluation in accordance with IWA-5250(a)(2), if leakage occurs at a bolted connection, the bolting must be removed, VT-3 visually examined for corrosion, and evaluated in accordance )

with IWA-3100. In lieu of this requirement, the licensee has proposed to evaluate the bolting to determine its susceptibility to corrosion. The proposed evaluation will consider, as a minimum, joint bolting materials, the corrosive nature of the process fluid, the leakage location and history of leakage at the joint, the service age of the bolting materials, and visual evidence of corrosion at the assembled connection.

Based on the items included in the evaluation process, the staff determined that the evaluation proposed by the licensee presents a sound engineering approa0h. In addition, if the initial evaluation indicates the need for a more detailed analysis, the bolt 1

i

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, closest to the source of leakage will be removed, VT-1 visually examined, and evaluated in accordance with IWA-3100(a). The acceptance criteria for the VT-1 examination was not in the relief request but was clarified by the April 15,1999, PECO letter. The VT-1 examination criteria are more stringent than the simple corrosion evaluation described in IWA-5250. The licensee also clarified in the same letter that it will perform its evaluations in accordance with the Code provisions of IWB-3140, as supplemented by the elements noted above. The staff concludes that the licensee's proposed alternative provides an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the licensee's proposed alternative is authorized for the first and second ISI intentals for both units.

2.10 Request for Relief No. RR-23, Revision 1: ASME Code,Section XI, Examination Category C-H requires a VT-2 visual examination during hydrostatic tests of Class 2 systems performed in accordance with IWC-5222 near the end of the interval.

lWA-5213 states that, for system hydrostatic tests of insulated systems, a 4-hour hold time is required after attaining the test pressure and temperature; a 10-minute hold time is required for non-insulated systems or components.

1 Pursuant to 10 CFR 50.55a(a)(3), the licensee proposed an alternative to the hold time requirement of the Code and Code Case N-498-1 for the high pressure coolant injection (HPCI) pump turbine and associated steam supply / exhaust lines. The licensee stated:

The system pressure test described in Code Case N-498-1 will be conducted as required, except that a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> hold time will be used in lieu of the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> hold 1 time requirement. This 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> hold time will match the hold time which has bann required for the previousSection XI ISI Program pressure testing of this system.

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

As a part of the Emergency Core Cooling Systerr (dCCS), the High Pressure Coolant Injection (HPCI) System is not required to operate during normal plant operation. This system is, however, periodically tested in accordance with other applicable requirements. These periodic tests are conducted to verify the operability of the applicable components. The functional test conducted for the HPCI Pump and associated turbine steam supply and exhaust system normally includes approximately 90 minutes of pump run time. In order to satisfy the d.

hour hold time requirement of Code Case N-498-1, the test would require a HPCI pump run in excess of 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> (hold time plus examination time). Running the HPCI System functional test for this length of time is not practical, and represents an undue hardship on the facility, without a compensating increase in the level of quality and safety.

Operating the HPCI Pump for the period of time required to satisfy the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> hold time would subject the facility to unnecessaiily excessive heat loads.

Control of these heat loads would require the operation of additional safety related equipment, and challenge the Technical Specification limitations placed on the maximum allowable Suppression Pool water temperature. ,

. I l

Removal of the insulation from the subject components, in order to qualify for the 10 minute hold time allowed by the Code Case, would be equally burdensome.

The cost associated with insulation removal and reinstallation, including resource diversion, radiation exposure, and additional radwaste would not be warranted. l i

Additionally, the Section XI periodic pressure test requirements, which have l

been imposed on this system during the first inspection interval (Functional Test,  !

per IWA-5211(b)), only require a 10 minute hold time.  !

Further, the ASME Section XI Committee is in the process of revising Code Case N-498-1 to remove the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> hold time requirement. This proposed revision is in recognition of the unusual difficulties and hardship imposed by the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> hold time on certain systems.

Evaluation:

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The Code specifies a 4-hour hold time prior to performing the VT-2 visual examination during the hydrostatic test of insulated systems. To achieve the required 4-hour hold i time, the licensee stated that the HPCI pump would be required to run in excess of 5 .

hours. Operating the HPCI pump for this duration would cause the Suppression Pool l

water temperature to rise, and consequently, require the startup of other safety-related ,

systems to maintain the Suppression Pool water temperature within Technical j Specifications. Therefore, the 4-hour hold time results in a hardship on the licensee.

The licensee proposed a 1-hour hold time before the VT-2 visual examination in lieu of a 4-hour hold time for insulated systems as required by the Code and Code Case 498-1.  !

The staff determined that the hold time of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> prior to the VT-2 visual examination of insulated portions of the subject system provides reasonable assurance of identifying a j leak and examining the structuralintegrity of the subject components. Compliance with I the Code and Code Case 498-14-hour hold time requirements would result in a hardship without a compensating increase in the level of quality and safety. Therefore, j the licensee's proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) for j the first (LGS Unit 2) and second ISI intervals (LGS Units 1 and 2).

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3.0 CONCLUSION

i I

The NRC staff concludes that certain inservice examinations cannot be performed to the extent  ;

required by the Code at the LGS Units 1 and 2, as follows: '~

l

a. No. RR-01(Part 1), Revision 2. The licensee's proposed alternative to the augmented reactor pressure vessel (RPV) examination requirements of 10 CFR 50.55a(g)(6)(ii)(A) provides an acceptable level of quality and safety for the subject RPV weld and is l authorized pursuant to 10 CFR 50.55a(g)(6)(ii)(A)(5) and 10 CFR 50.55a(a)(3)(i) for the i first ISI interval for LGS Unit 1.  !

b. No. RR-01(Part 2), Revision 2. Based on the NRC's assessment of BWRVIP-05 and the guidance promulgated in GL 98-05, the licensee's proposed alternative to discontinue examining the Catagory B-A, Item B1.11, circumferential welds provides an acceptable level of quality and safety and is authorized pursuant to 1

1

10 CFR 50.55a(a)(3)(i) for the remaining IS'l intervals in the current licensing period for both units.

c. No. RR-05, Revision 2. The licensee's proposed performance of surface examinations of ASME Class 2 integral attachment welds in accordance with the 1995 Edition, with the 1996 Addenda, of ASME Section XI provides reasonable assurance of structural integrity of these components. The proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) for the first and second ISI intervals for both units.

d. No. RR-11, Revision 1. The licensee's proposed alternative to use the ASME Section XI,1995 Edition through the 1996 Addenda, Table IWB-2500-1, Examination Category B-K, as supplemented by Code Case N-323-1, provides reasonable assurance of structuralintegrity of the subject components. The licensee's proposed altemative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) for the first and second ISI intervals for both units.

e. No. RR-12 (Part 1). The licensee's proposed alternative to use Code Case N-416-1 and its additional alternative to perform an additional surface examination on the Class 3 root pass layer of butt and socket welded joints when surface examination is required for the final weld by the 1992 Edition of ASME Code, Section Ill, provides an acceptable level of quality and safety. The licensee's proposed alternative to use Code Case N-416-1 and its additional altemative examination is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the first and second ISI intervals for both units.

f. No. RR-12 (Part 2). The licensee's proposed alternative to use Code Case N-498-1 for hydrostatic testing provides reasonable assurance of leakage integrity. The licensee's proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) for Class 1,2, and 3 systems for the first and second ISI intervals for both units.

g. No. RR-12 (Part 3) was previously authorized for the first ISI interval for LGS Units 1 and 2 in an NRC Safety Evaluation dated October 9,1997. The licensee requested that the previously approved authorization to implement the alternatives contained in Code  !

Case N-546," Alternative Requirement for Qualifications of VT-2 Visual Examination Personnel," be extended to the second ISI interval for LGS Units 1 and 2. There are no technical changes in the licensee's relief request and, therefore, the NRC staff concludes that its findings as stated in the October 9,1997, staff evaluation remain valid. The proposed alternative continues to provide an acceptable level of quality and safety and is authorlzed pursuant to 10 CFR 50.55a(a)(3)(i) for the second ISI interval for both units.

h. No. RR 12 (Part 4). The licensee's proposed alternative to use Code Case N-524,

" Alternative Examination Requirements for Longitudinal Welds in Class 1 and 2 Piping,Section XI Division 1," provides an acceptable level of quality and safety cr.d L-authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the first and second ISI intervals for both units.

i. No. RR-12 (Part 5). The proposed alternative to use an engineering evaluation process, I and perform a VT-1 examination on bolting when required, provides an acceptable level of quality and safety. Therefore, the licensee's proposed alternative with a VT-1 examination is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the first and second ISI intervals for both units.

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J. No. RR-23, Revision 1. The licensee's proposal for a 1-hour hold time before VT-2 visual exantination in lieu of a 4-hour hold time for insulated systems as required by the Code and Code Case N-498-1 provides reasonable assurance of identifying a leak and the structuralintegrity of the subject components. The licensee's proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) ior the first ISI interval (LGS Unit 2) and the second ISI interval (LGS Units 1 and 2).

Principal Contributor: T. McLellan Date: September 13, 1999 i

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