ML20199C123

Safety Evaluation Granting Second 10-yr Inservice Insp Program Plan Relief Request

ML20199C123
Person / Time
Site:	Byron
Issue date:	01/13/1998
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20199C085	List: ML20199C081 ML20199C123
References
NUDOCS 9801290136
Download: ML20199C123 (44)

Text

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{ NUCLEAR RESULATORY COMMisS60N  ;

wanweton, e.c. meaM*M SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION BECOND 10 YEAR INTERVAL INSERVICE INSPECTION PROGRAM PLAN  !

REQUE8h FOR RELIEF l COMMONWEALTH EDISON COMPANY  !

l i

SYRON STATION. UNITS 1 AND 2 -

! DOCKET NOS. STN 50 454 AND STN 50 455

1.0 INTRODUCTION

l The Technical Specifications (TS) for Byron Nuclear Power Station, Units 1 and 2, state that the l inservice inspection of the American Society of Mechanical Engineers (ASME) Code Class 1,2,

< and 3 components shall be performed in socord nce with Section XI of the ASME Boiler and Pressure Vessel Code (Code) and applicable addenda as required by 10 CFR 50.55a(g), except 4 where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). In 10 CFR 50.55a(a)(3) H states that altematives to the requirements of paragraph (g) may be used, when authorized by the NRC, if; (i) the proposed aNematives 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.

J Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1,2, and 3 components (including i supports) shall meet the requirements, except the design and access provisions and the pre-servios examination requirements, set forth in the ASME Code,Section XI,

• Rules for inservice

. Inspection of Nuclear Power Plant Components," to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first ten year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) twelve months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein.

i ENCLOSURE I

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1 The applicable edNion of Section XI of the ASME Code for the current Byron Nuclear Power f Station, Units 1 and 2 second 10 year inservice inspection (181) interval is the 1969 Eddion, j Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance with an I examination requirement of Section XI of the ASME Code is not practical for its facility,  !

information shall be submitted to the Commission in support of that determination and a request  !

made for relief from the ASME Code requirement. After evaluation of the determination, pursuant to 10 CFR 50.55a(g)(6)(l), the Commission may grant relief and may impose attemative  !

requirements that are determined to be authortrod by law, will not endanger life, property, or the common defense and security, and are otherwise in the public interest, giving due consideration 3 to the burden upon the licensee that could result if the requirements were imposed.

By letter dated February 23,1996, Commonwealth Edison Company (licensee), submitted second ten year interval requests for relief from the ASME Section XI requirements for Byron

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Nuclear Power Station, Units 1 and 2. The licensee provided additional information in its letters -

dated August 12,1996 and December 16,1996.

L2.0 EVALUATION <

The staff, with technical assistance from its contractor, the Idaho National Engineering and ,

Environmental Laboratory (INEEL), has evaluated the information provided by the licen>>e in  ;

support of its second ten year inservice inspection interval program plan requests for relief for  !

Byron Nuclear Power Station, Units 1 and 2. Based on the results of the review, the staff adopts  !

the contractor's conclusions and recommendations presented in the Technical t.etter Report (TLR) attached. t Request for Relief No,12R45 (Revision 2): Section XI, Table IWC 25001 Examination Category C 8, item C2.32, Residual Heat Removal Heat Exchanger (RHRHX) Nonle to-Shell Wold requires a volumetric examination as defined by Figure IWC-2500-4(c). This examination  :

is specified for noule to shell (or head) welds with reinforcing plates in vessels greater than W

inch nominal thickness when the inside of the vessel is accessible for noule exarninations.

Examinations are limited to noules at terminal ends of piping runs selected for examination under Examination Category C F.

Pursuant to 10 CFR 50.55a(s)(3)(i), the licensee proposes to perform a best effort ultrasonic examination of RHRHX noule to vessel Wolds RHXN-01 and RHXN-02 for Units 1 and 2, respectively. There are two noule to vessel welds per heat exchanger and two RH heat i exchangers in each unit bringing the total number of welds under consideration to eight. ,

Additionally, a surface examination will be performed on each noule in each inspection period during the second inspection interval.-

The Code requires 100% volumetric examination for the subject RHRHX noule-to shell welds, in lieu of Code-required volumetric examination, the licensee has proposed to perform a best-effort ultrasonic examination on one of the two noules in each plant and a surface examination on each noule each inspection period during the second 10 year interval. The fillet weld configuration makes ultrasonic examination of the subject welds difficult to perform to the extent required by the Code. Even with this difficult configuration, the licensee can complete an E estimated 55.6% of the Code-required volumetric examination foi each of the welds, in addition L - to the best effort ultrasonic examination, the licensee will perform surface examinations on the 2

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. l nossles once each penod. The best-effort uhrssonic examination, in combination with the [

surfeos examination each inspection period, should detect any existing pattoms of degradation,  ;

4thus, the licensees's proposed attemative provides an acceptable level ed quality and safety.  !

Therefore, the licensee's proposed allemative is authortred pursuant to 10 CFR 50.55a(s)(3)(i). l i noguest for Relief No.12R46: sodion XI, Table IWC 25001, Examination Category C-C, hem I i C3.30, integrally Welded Attachments to Pumps requires 100% surface examination as defined l by Figure IWC-2500 5 for integrally welded attechments to pumps. Examinations are limited to i attachment welds to components examined under Examination Categories C F and C G.

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Pursuant to 10 CFR 50,55a(s)(3)(l), the lioerisee proposed an altemative to the Code required

, surface examination of imegrally wolded attachments to the centrifugal charging pumps and '

residual heat removal (RHR) pumps; these attachments are:

CVPE 01 CVPE 02 CVPE-03 CVPE-04 RHPE-01 RHPE 02 RHFE-03 RHPE-04 i The licensee stated:

'A Visual, VT.1 examination will be performed on the portions of the subject welds a which are inaccessible. The Code required surface examination will be performed on the j accessible portions of the subject welds."

The Code requires 100% surface examination of the subject integral attachment welds. l However, portions of the welds are located between the pump and the concrete support, making '

. them inaccessible for surface examination. In lieu of the Code requi'ed,100% surface examination, the licensee will perform the surface examination on the accessible portions of the welds and a VT 1 visual examination on the inaccessible portions.

The licensee's proposed attemative, to visually examine oortions of the subject integral attachment welds that are inaccessible for surface examination, in combination with tM Code-  ;

required surface. examination of the accessible portions, will detect any significant pettoms of  ;

degradation that could affect the structuralintegrity of the integral attachments. Since the entire length of each weld will be examined-either surface or visual examination Abe licensee's attemative provides an acceptable level of quality and safety. Therefors, the hcensee's proposed i altemotive is authortred pursuant to 10 CFR 50.55a(a)(3)(i).

Request for Relief No.12R 07: Section XI, Table IWC 25001, Examination Categories C-F 1 and C-F 2, items C5.11N, C5.12N, C5.51N and C5.52N, Class 2 Piping Wolds require volumetric

, - and surface examination of a 7.5% sample of piping wolds greater than or equal to 3/8-inch nominal thickness and greater than 4-inch nominal pin size (NPS) Wolds less than 3/8-inch '

nominal well thickness are included in the population but excluded from examination.

However, the licensee is using Code Case N 406 2, A#emative Rades for Examination of Class 2 Piping, Sochon XI, Division f, in lieu of the requirements of the Code for the examination of Class 2 piping welds. Code Case N-406 2 has been approved for general use by refersace in Regulatory Guide 1.147, inservice Inspection Code Case Acceptabluty, ASME Section XI, 3

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n CMalen f. Code Case N408 2, Tables 1 and 2, Examination Categories C F 1 and C F.2, Hems  !

j C5.11N, C5.12N, C5.51N and C5.52N,' requires volumetric and surface examination as defined  !

by Figure IWC 2500 7 (of the Weier 1983 Addenda) for piping welds greater than or equal to i

3/S inch nominal thickness and greater than 4 inch nominal pipe size (NPS).

4 1 Pursuard to 10 CFR 50.55a(s)(3)(i), the licensee proposed to include Class 2 piping wolds less

than 3/8 inch thick but greater than 1/4-inch nominal thickness in the 7.6% volumetric and i surface examination sample. Spooifloally, the licensee stated

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• Syron Station will select for examination nonexempt, Code Class 2 piping welds per  ;

Code Case N-408 2, Tables 1 and 2 Note (2) without eliminating wolds with nominal wall  :

thickness less than .375 inch from consideration. The wolds selected which are nominal  !

wall thickness less than .375 inch would be volumetrically and surface examined per the j requirements of Code Case N-406 2, Category C F.1, item Nos. C5.11 and C5.12 and ,

Category C F 2, item Nos. C5.51 and C5.52. Wolds with Nominal Wall Thickness less i

' than .250 inch well will not be included as part of inis attemative selection methodology."

i Code Case N 408 2 requires volumetric and surface examination of a 7.5% sample of piping l

welds greater than or equal to 3/8 inch nominal thickness and greater than 4-inch nominal pipe ,

i size (NPS). Wolds less than 3/8 inch nominal well thickness are included in the population but- ,

excluded from examination. Code Case N-408 2 has been approved for used by incorporation in j 4

Rev6sion 11 of Regulatory Guide 1.147, inservloe Inspection Code case Accepta6///fy ASME  ;

Sec6on X/, OMalon f. The 1.censee's experience indicates that meaningful UT examinations can  :

be performed on piping welds as small as 1/4-inch thick. Therefore, the licensee has proposed i to use sampling ortleria that do not exclude thin walled p! ping in the Residual Host Removal (RHR), Emergency Core Cooling (ECC), and Containment Heat Removal (CHR) from volumetric l and surface examinations. The proposed change reduce 6 the number of examinations on piping wolds greater than 3/8-inch but does not affect the overau examination sample size for Class 2 piping welds since piping welds less than 3/8. inch will nt;w be included in the examination i

sample, The staff concurs with the licensee's position and con':ludes that it is technically prudent to examme a representative sample of tNn walled piping welds in the RHR, ECC, and CHR systems. TNs can be accomplished by either augmenting the examination sample or by '

substituting thin walled welds for thick walled welds. The licensee has opted to substitute thin-walled Class 2 piping. Since the licensee has not reduced the overall examination sample, this attemative provides an axoptable level of quakty and safety. Therefore, the licensee's proposed altemotive is authorized pursuant to 10 CFR 50.55a(s)(3)(i).

Request for Relief No.12R 08

Section XI, Table IWC 25001, Examin.nion Category C-F.1 and

! C-F 2, item C5.12, C5.12N, C5.52 and C5.52N, Class 2 Longitudinal Piping Wolds require 100%

. surface and volumetric examination, as defined by Figure IWC 2500 7, for 2.5T of longitudinal  ;

piping welds from intersecting circumferential wolds. Pursuant to 10 CFR 50.55a(a)(3)(i), the  !

licensee has proposed altemative scan coverage requirements in lieu of the volumetric and ,

surface examination coverage requirements of the Code for Class 2 longitudinal welds.

. Speal6cally, the licenses stated:  !

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T.4 The letter *N' designates piping welds less than 3/8-inch nominal wall taickness. l 4 .

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• Surface and volumetric examinations shall be performed, as applicable, on the length of

- the longitudmal weld that is normally examined during examination of the intersecting

circumferential welds (s). The volumetric examination at the intersection of

! circumferential and longitudinal welds will include both transverse and parallel scans

within the length of the longitudinal weld that falls within the circumferential weld examination boundary."  !

ASME Section XI requires for Class 2 repmg wolds, the length of longitudinal wold 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 pr' ,,0 sed altemative is to examine only the portions of .

longitudinal wold contained within the examination area of the intersecting circumferential wold.  !'

This altemative is contained in Code Case N 624, Allemative ErarrWnation Regulroments for Longitudinal WeMs in Class f and Class 2 Piping, which has previously been found acceptable for use at other facilsties.

Longitudinal welds are produced during the manufacture of the piping, not in the field as j circumferential welds are. Consequently, the welds are fabricated under the strict guidelines

specified by the manufacturing standard, which provides assurance of structural integrity. These welds have also been subjected to the preservice and initialinservice examinations, which

provide additional assurance of structuralintegrity. No significant loading conditions or material

degradation mechanisms have become evident to date that specifically relate to longitudinal

! seem 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 altemotive provides an acceptable level of quality and safety. Therefore, the  ;

licensee's proposed altemative is authorized pursuant to 10 CFR 50.55a(a)(3)(i).

Request for Relief No,12R 09: Section XI, Table IWC 25001, Examination Categories C F 1 and C F 2, items C5.41 and C5.81, Circumferential Branch Connection Wolds require 100%

surface examination as defined by Figures IWC 2500-g to .13 inclusive, for circumferential branch connection welds in branch piping greater than or equal to 2 inch nominal pipe size (NPS).

l Pursuant to 10 CFR 50.55a(a)(5)(iii), relief is requested from performing the Code required surface examination of the 6 inch main steam relief valve line branch connections and the 16-inch residual heat removal piping to 24 inch safety injection piping branch connections listed in the table below, in addition, the licensee proposed as an attemative examination to perform a surface examination of the saddle to main pipe weld and the saddle to branch pipe weld, when the pressure retaining weld is made inaccessible due to the use of a reinforcement saddle.

- Additionally, a VT 2 visual examination of these areas will be performed in conjunction with the required Class 2 System Pressure Tests.

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Table 12R.09 UnM Exam. Cat. Nem Line No. Wold Numbers 1 C-F 1 C5.41 1Sl06BA 24 C18 1S106B8 24 C24 CF2 C5.81 IMS07BA 26 C03,C04,C05,C09,C10 IMS07B8 28 C03,C04,C05,C06,C10 IMS07BC 28 C03,C04,COS,C06,C07 IMS07BD-28 C03,C04,C05,C09,C10 2 CF1 C5.41 2Sl06BA 24 C26 2Sl06BB 24 C26 CF2 C5.81 2MS07AA 28 C12,C13,Cid,C15,C16 2MS07AB 28 C15,C16,C17,C18,C19 2MS07AC-28 C15,C16,C17,C18,C19 2MS07AD 28 C12,C13,Cid,C15,C16 The Code requires a 100% surface examination of each of the subject branch connection welds.

However, access to these welds is completely obstructed by reinforcing saddle plates that are fillet welded over the pressure retaining bran h connection welds. Therefore, the design makes

. the Code requirements impractical for these branch connections. To gain access for examination, the saddle plates would have to be removed and the branch connections redesigned and modified. Imposition of this roquirement would create a considerable burden on the licensee.

In lieu of the Code required surface examination, the licensee will perform a surface examination of the fillet welds used to attach the saddle plate to the main pipe and branch pipe. Examination of these welds will detect any gross structural deformation and confirm the overallintegrity of the branch connection. in addition, tt,a licensee will perform VT 2 visual examinations of these areas in conjunction with the Class 2 pressure tests. As depicted in the licensee's attached figure, each of the saddle plates includes a telltale hole. Any leakage that could occur from the inaccessible pressure-retalning weld would be detected during the Class 2 pressure tests. The staff concludes that the altemate surface examination, along with the Code-required pressure tests, ensures the structuralintegrity of the subject branch connections. Therefore, staff concludes that based on the impracticality of the Codo requirements for the subject welds and the assurances provided by the altemative surface examination and Code required pressure tests, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i).

Request for Relief No,12R 10: Section XI, Table IWC-25001, Examination Category C-H, items C7.30, C7,40, C7.70 and C7.80, Pressure Testing of Containment Penetration Piping

- Attached to Non Classeo Piping require a system leakage test at operating pressure for pressure retaining piping and valves.

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, Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed to perform 10 CFR 50, Appendix J

leakage tests as an attemative to the Code required pressure tests for containment penetration l f

l piping whh attached non-classed piping. The leakage tests will be performed at no less than the peak calculated containment pressure (44.4 psig) as defined in the Byron Technical i

Spootncations and Byron Station will implement station VT surveillances to detoot and locate

! extemal piping leakage.  !

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The Code requires that a W 2 visual examination be performed during system pressure testing for Class 2 pressure-rotalning piping. As an altemative, the licensee proposes to implement the  ;

requirements of 10 CFR 50, Appendix J for the subject piping. This attemative is contained in ,

ASME Code Case N 522, Pressure Teaung of Containment PenetreHon Mping, which has ,

previously boon found acceptable for use at other facilities with certain conditions that licensees ,

have committed to follow.

The subject piping is classified as Class 2 because it penetrates primary reactor containment ard t

is considered an extansion of the containment vessel Since the piping on either side of these penetrations is non-classed, the requirements of Appendix J are more appropriate than those of Examination Category C H. Appendix J pressure tests verify the leak tight integrity of the primary reactor containment and of systems and components that penetrate containment by localleak ,

rate and integrated leak rate tests. In Appendix J pressure tests, containment isolation valves and connecting pipe segments must withstand the peak calculated containment intomal pressure related to the maximum design containment. In addition, the staff has determined that the ,

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!~ Appendix J test frequencies are acceptable for assuring containment integrity. Therefore, the '

staff concludes that the use of Appendix J is acceptable for the subject penetration piping.

< The licensee has committed to perform the Appendix J testing at no less than the peak calculated containment pressure and will use station VT survei8!ances to detect and locale the

. source of the leakage. The staff concludes that the licensee's proposed attemative provides an acceptable level of quality and safety since h will test the subject penetrations for their intended function. Therefore, the licensee's proposed altemative pressure test is authorized pursuant to 10 CFR 50.55a(s)(3)(i).

Request fer Relief No.12R 11 (Revision 1)' *aragraph IWA 5242(a), VT 2 Visual Examination of Insulated Components requires that insulation shall be removed from pressure retaining boHed connections for VT 2 visual examination in systems borated for the purpose of controlling reactivity.  ;

Pursuant to 10 CFR 50.55a(s)(3)(i), the licensee has proposed the following ahomative to the Code requirement to remove insulation at bohed connections for VT t examination during system

- pressure testing (as stated).

• For systems borated for the purpose of controlling reactivity, a system pressure test of inservice leakage test shall be performed in accordance with the frequency required in .

tables IWX 2500 without the removal of insulation from the bolted connections.

'A minimum 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> hold time pr6or to the VT 2 visual examination shall be invoked to allow for leakage propagation from the insulation.  !

" Additionally, the insulation shall be removed from these bolted connections and a VT 2 examination shall be conducted. During this VT 2 examination, the bohed connections  !

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o are not required to be pressurized. The frequency for these inspections shall be in accordance with the system examination frequencies specified in Tables IWX 2500, Categories B-P (each refueling outage), C H (each period), and D A (each period).

'Any evidence of leakage, either while insulated or while delnsulated, will result in evaluations for corrective measures in accordance with IWB 5?.50 (as modified for Byron Station by approved Relief Request l2R 12').*

The Code requires the removal of allinsulation from pressure retalning bolted connections in systems borated for the purpose of controlling reactivity when performing VT 2 visual examinations during system pressure tests. As an altomative, the licensee has proposed to perform the VT 2 visual examination with the insulation in place after a minimum 4-hour hold time. In addition, the insulation will be removed for direct visual examination each refueling outage for Class 1, and each period for Class 2 and 3 components.

The licensee's proposed allemative is essentially equivalent to Code Case N 533, Allemative Requirements for VT 2 Visunt Examination of Class f Insulated Ptsssurs Retalning Bolted Connections,Section XI, DMs/on f, except the proposed attemative was extended to address Code Class 2 and 3 bolted connections. Code Case N 533 is currently under review by the NRC staff and has not yet been approved for use by incorporation into Regulatory Guide 1.147, inservice Inspection Code Case Acceptability. The NRC staff has authorized its use as an attemative on a plant specific basis.

For Class 1 systems, the licensee's proposed attemative provides a thorough approach to ensuring the leak tight integrity of systems borated for the purpose of controlling reactivity. Fir:,1, the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> hold time allows any leakage to penetrate *he insulation, and thus provides b means of detecting any significant leakage with the insulation in place. Second, by removing the insulation each refueling outage, the licensee will be able to detect minor leakage indicated by the presence of boric acid crystals or residue. This two-phase approach will provide an acceptable level of quality and safety for bolted connections in oorated systems. Therefore, the licensee's proposed attemative is authorized pursusnt to 10 CFR 50.55a(s)(3)(i) for use on Class 1 systems.

The licensee proposed as an allemative for Class 2 and 3 systems to use Code Case N 533, to perform VT 2 examinations without removing insulation. In addition, it propostd that for Class 2 and 3 systems to perform the VT 2 examinations each period (40 months) verses Code Case N 533 frequency of every outage for Class 1 systems. The staff concluded that for Class 2 and 3 systems the licensee's proposed attemative frequency of each period is unacceptable, because undetected boron leakage could occur resulting in undetected corrosion. Consequently, the proposed attemative does not provide an acceptable level of quality and safety. Therefore, the licensee's proposed attemative is denied for the Class 2 and 3 systems.

Request for Relief No.12R 13: Section XI, IWF 5300, Inservice Examination and Test Requirements for Snubbers. Relief is requested for Byron Station Units 1 and 2 from the ASME B&PV Code,Section XI, Article IWF 5000, Subarticle paragraph IWF 5300(a) requirements for visual examination of Code Class snubbers.

1 l Evaluated in NRC Safety Evaluation Report dated July 22,1996.

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.. r a l 4 Byron Station Technical Specifications (TS) 4.7.4 include a comprehensive program for visual  !

examination of all safety related hydraulic and mechanical snubbers. The program scope encompasses all Code Class 1,2, and 3 anubbers. Byron Station TS 4.0.5 also includes requirements for visual examination of Code Class 1,2, and 3 snubbers per ASME Section XI  !

and ASME/ ANSI OMa 1988, Part 4. [

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Because all safety related snubbers at Byron Station are also Code Class, the overlap of the  ;

vlausi examination programs per T8 and ASME Section XI for Code Class snubbers presents an  !

. unnecessary redundancy. Since the visual examination in both programs is rigorous, the  !

iWp::"':s of only one program is necessary to assure en acceptable level of quality and safety.

The T8 visual examination program and the program presented in OMa 1988, Part 4 per IWF. l 5300(a) are similar in content. . Both programs include parallel criteria for vit.ual examination,

. examination frequency, examination size, examination evaluation, corrective action and  !

eramiration documentation.

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- The licensee considers that the snubber visual s,xaminations required per the T8 meet the intent of the ASME B&PV Code,Section XI, Article IWF 5000, Subarticle paragraph IWF 5300(a) which refers to the ASME/ ANSI OMa 1988, Part 4 requirements and provides an acceptable level of quahty and safety, i

Byron Station proposed to perform visual examinations of Code Class snubbers in accordance  !

with TS 4.7.8 in lieu of the requirements of ASME/ ANSI OMa 1988, Par 14. The visual 4

examinations performed per the T8 will include the snubber rtructural attachments to the i foundation or supporting structure up to and including the fasteners for connecting the snubbers

_ to the pipe attachment or component attachment. The examination of snubber integral and nonintgral attachments required by Subarticle paragraph IWF 5300(c) will be performed in accordance with Section XI, Subsection IWF. Further, if any part of the boundary included in the ,

T8 visual inspection cannot be verified to be functional due to insulation interference, the ,

insulation will be removed to satisfy the T8 requirement. ,

Personnel performing the snubber visual examinations will be qualified to perform Visual, VT 3 i examinations per Section XI, Subsection IWA, pamgraph IWA 2300.

In response to the staff's questions with regard to the use of the Byron Station's T8 4.7.8 for {

snubber preservior, repair and replacement requirements, the licensee revised the relief request (12R 13 Revision 1) to delete any reference to the TS requirements for snubber preservice inspections.

Relief Moquest 12R 13 Revision 1, proposes as an altomative to the visual examinations of the

. ASME B&PV Code,Section XI, Subarticle IWF 5300, Paragraph (a) requirements to perform all snubber visual inspections at Byron Station Units 1 and 2 in accordance with T8 4.7.8. The Byron Station's Units 1 cad 2 TS 4.7.8 provide snubber visual examination requirements that are consistent with ASME/ ANSI OMa 1988, Part 4 requirements. The Byron Station's TS 4.0.5 also includes requirements for visual examination of Code Class 1,2, and 3 snubbers per the ASME  !

B&PV Code,Section XI, Subarticle IWF 5300, Paragraph (a) which refer to the ASME/ ANSI -

OMa 1988, Part 4. Al! safety related snubbers at the Byron Station are Code Class snubbers, therefore, the T8 contain an unnecs ssary redundancy for visual examination of snubbers.

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Relief Request 12R 13 Revision 1 proposed aNemative to perform the visual examination of Code Class snubbers at Byron Station in accordance with TS 4.7.8 and TS 4.0.5 in lieu of ASME B&PV Code,Section XI, Subarticle 5300, paragraph (a) requirements, which refer to the ASME/ ANSI OMe 1988, Part 4, provides an acceptable level of quality and safety. The staff has determined, pursuant to 10 CFR 50.55a (3)(a)( his ahomative is acceptable. /

Request for Relief No.12R 18: Section XI, Table IWA-4700(a) requires that a systern hydrostatic test be performed in accordance with IWA 5000 after repairs by welding on the pros so-retaining boundary Pursuant to 10 CFR 50.55a(a,(3)(i), the licensee p*oposes to emp.sy the rules in Code case N-416 t with the additional NDE roy" wnts stated below as an allemative to Section XI requirements (as stated):

'After welded repairs or installation of replacement hems by welding, the following altemotive requirements will be met in lieu of performing the hydrostatic pressure test required per paragraph IWA-40CD:

(a) Non destructive examination (NDE) will be performed on the repaired / replaced welds or welded areas in accordance with the methods and acceptance criteria of the applicable fiubsection of the 1992 Edition of Section Ill.

(b) A VT 2 visual examination will be performed at nominal operating pressure and temperature in cor.juncthn with a rr; tem leakage test in accudence with paragraph IWA 5000 of the 1992 Edition of Se dion XI, prior to or immediately upon retum of the component to service.

(c) Use of this R=!ief Request shall be documented on an NIS 2 Form.

1 (d) When NDE is to be conduct 6,d per Subsection ND-5222 on a Code Class 3 component, an additional surface examination shall be performed on the root (pass) layer.

(e) When Code Class 3 repair or replacement activities involve socket / fillet weltis, a surface exantination shall be performed on the subject socket / fillet welds."

Section XI of the Code requires a system hydiostatic test to be performed in accordance with lWA 5000 after repairs by welding on the pressunr-retaining boundary. The licensee proposes to implement the altemative to hydrostatic pressure tests contained in Code Case N-4161 for Code Class 1,2, and 3 repairs /replaicements, in addition, the licensee will supplement the pressure test with an additional surface examination on the root pass layer of Class 3 repair / replacement welds or welded areas.

Code Case N-4161 specifies that nondestructive examination (NDE) of the welds be performed in accordance with the applicable subsection of the 1992 Edition of Section Ill. This Code Case alsu allows s VT-2 visual examination to be performed at nominal openating pressure and -

temperature in cor$ unction with a system leakage test, in accordance with paragraph IWA 5000 of the 1992 Edition of Section XI. Comparison of the system pressure test requirements of the

- 1992 Edition of Section XI to those of the 1989 Edition of Section XI, the latest Code edition referenced in 10 CFR 50.55a, shows that:

+ the test frequencies and pressure conditions are unchanged; 10

J

• the hold times either remained the same or increased;

• the terminology associated with the system pressure tat.t requirements for all three  ;

Code classes has been clarified and streamlined; and

• the NDE requirements for welded repairs remain the same.

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. Accordingly, hydrostatic pressure testing is primarily regarded as a means to enhance leak detection during the examina*. ion of components under pressure rather than a> 7 measure of the structuralintegrity of the components.

Following ;;:"-bg, the Code requires volumetric examination (depending on well thickness) of r6 pairs or replacements in Code r" ass 1 and 2 piping components, but only requires a surface

- examination of the final weld pas., in Code Class 3 piping. There are no ongoing NDE requirements for Code Class 3 components except for VT 2 visual exaTination for leaks in conjunction with the 10 year hydrostatic tests and the periodic pressure tests. However, the staff concludes that the examinations required by Code Case N-416-1 are commensurate for Class 3 systems when 1) a surface examination is performed on the root pass layer of butt and socket ,

welds, and 2) a system pressure test at nominal operating pressure is performed.

Con.6dering the previous acceptance of Code Case N-416 by the NRC and the supplemental surface examination on the root pass for Olsss 3 systems, it is concluded that the licensee's l proposed altemative will provide an acceptable level of quality and safety. Therefore, licer.see's proposed altamative, to use Code Case N 4161 with a supplemental surface examination on the j root pass layer of butt and socket welds, is authorized pursuant to 10 CFR 50.55a(a)(3)(l). The l use of the Code Case is 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, if the licensee intends to i

continue to implement this Code Case, the licensee must follow all provisions in Code Case l N-416-1 with limitations issued in Regulatory Guide 1.147, if any.

Request for Relief No.12R 18: Section XI, Table IWD 2500-1, Examination Categories D-A, D.

l- -

B, and D C require hydrostatic testing nf Class 3 pressure retaining components in accordance L

with IWA-5000 and lWD 5223. Purst mt 'o 10 CFR 50.55a(a)(3)(i), the licensee has proposed to employ the rules in Code Case N-4g84 m in altemative to the 10 year hydrostatic pressure test . .

required by Table IWD 25001 Categories D-A, D B, and D C as follows (as stated):

"(1) A system pressure test shall be condWed at or near the end of each inspection interval or durine & Jce inspection period of each inspection interval of Inspection l Program B.

(2) The boundary subject to to::t pressurization during the system pressure test shall I extend up to and including the first normally closed valve or valve capable of automatic closure as required to perform the safety system function.

-(3) The system shall be pressurized to nominal operating 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 noninsulated systems. The system shall be -

maintained at normal operating pressure during the performance of the VT-2 examination, 11 l

l

?' l I l

. , l (4) The VT 2 visual examination shall include all components rithin the boundary identified in (2) above.

l (5) Test instrumentation specified for a hydrostatic pressure test is not required."

The Code requires a system hydrostatic test once per interval in accordark.a with the requirements of IWA 5000 for Class 3 pressure-roteining systems. In lieu eMe Code required l 4 hydrostatic testing, the licensee has requested authorization to use Code Cam N-4981,

• Memetin Rules kr 10 Year System Hydrostatic Testing kr Class 1 2, and 0 Cystems, dated May 11,1994 The system hydrostatic test, as stipulated in Section XI, is not a test of tSe structural integrity of the system but rather an enhanced leakage test.8 Hydrostatic testing caly subjects the piping components to a smallincrease in pressure over the design pressure; therefore, piping dead ,

weight, thermal expansion, and seismic loads present far greater challenges to the structural integrity of a system. Consequently, the Section XI hydrostatic pressure test is primarily regarded as a means to enhance leak detection during the examination of components under pressure, rather than as a method to determine the structumi integrity of the components. In addition, the i industry experience indicates that leaks are not being discovered as a result of hydrostatic test 4 pressures causing a preexisting flaw to propagate through the wall. In most cases leaks are being found when the system is at normal operating pressure, i

Code Case N-498, Memative Rules kr 10-Year System Hydrostatic Testing kr Class 1 and 2 Systems, was previously approved for general use on Class 1 and 2 systems in Regulatory Guide 1.147, Rev. 9.. For Class 3 systems, Revision N-498-1 specifies requirements identical to those for Class 2 components (for Class 1 and 2 systems, the altemative requirements in N-498-1 are unchanged from N-498), 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 VT 2 visual examination at nominal operating pressure and temperature in conjunction with a system leakage test performed in accordance with paragraph IWA 5000 of the 1992 Edition of Section XI.

Cim 3 systems do not normally receive the amount and/or type of nondestructive examinations i tid Gius 1 and 2 systems receive. While Class 1 and 2 system failures are relatively umww on, Class 3 leaks occur more frequently and are caused by different failure mechanisms.

%ed an a review of Class 3 system failures requiring repair during the last 5 years,d the most

. come ion causes of failure are eros ion-corros ion (EC), microbiologically-induced corrosion (MIC), '

l- and general corrosion. In general, licensees have implemented programs for the prevemion, detection, and evaluation of EC and MIC; therefore, Cless 3 systems receive inspection commensurate with their functions s'xl expected failure mechanisms.

Considering that Code Case N-498 was found to be an acceptable attemative in Regulatory Guide 1.147, Rev. 9, for Class _1 and 2 systems, and that Class 3 system components receive

-8. H.- Bush and R. R. Maccary, " Development of in Service Inspection Safety Philosophy for U.S.A. Nuclear Power Plants," ASME,1971

-Documented in Licensee Event Reports and the Nuclear Plant Reliability Data System databases.

, 12 L

, = t

'~

i.

inspections commensurate with their function and expected failure mechanisms, the licensee's proposed allemative, to use Code Case N-4961, for Class 3 system components provides an

acceptabl6 level of quality and safety. Therefore, tne licensee's proposed attemative is

authorized pursuant to 10 CFR 50.55a(s)(3)(i) for Class 3 system components. Furthermore, the '

3 licensee will continue to use Code Case N-498 for Class 1 and 2 system components.

- The use of the Code Case N-4981 is authorized for the current interval r r urel such time as the Code Ccse tw published in a future rev!aion of Regulatory Guide 1.047. At that time, if the

[ licensee intends to continue to implement inis Code Case, the licet.aoe must follow all provisions in Code Case N 4961 with limitations issued in Regulatory Guide 1.147, if any.

Request for Rollef No.12R 17 (Revision 2): The Code requires exarr.ination of integrally-wolded attachments as specified for Examination Categories B-H, B-K, C-C, D A, D 8, and D.C.

The Code stipulates volumetric or surface examinations, as =pp epri, and the extent of examinations. Pursuant to 10 CFR 50.55a(s)(3)(i), the licensee has proposed to use Code Case b N-50g, Altemale Rules $6r the Selection and Examination of Class 1, 2, and 3 IntegraMy H6lded L - Attachments,Section XI, Division 1, in lieu of the requirements of the Code for Class 1,2, and 3 integrally-welded attachments. The licensee stated:

'The requirements of Code Case N 509 will be used to select and examine integrally welded attachmentsi The selection of the integral attachments reflects 10% of the total of all i nonexempt (per lWX1220) ASME Class 1,2, and 3 piping, pump, and valve integral attachments, and in the case of multiple vessels of similar design, function, and service, an integrally wolded attachment of only one of the multiple vessels."

l The licensee has proposed to apply the requirements of Code Case N 50g as an ahomative to the Code requ!rements for the examination of integrally welded attachments on Class 1,2, and 3 piping and components. The licensee has alsn committed to supplement the Code Case with a minimum examination sample of 10% of integral attachments to non-exempt Class 1,2, and 3 components. Considering that most of the Code examination requirements are based on sampling to ensure the detection of service induced degradation, extending the sampling philosophy to the intog,ral attachment wolds provides an equivalent level of quality and safety.

~

Therefore, the licensee's proposed attemative to use Code Case N-50g with the minimum sample size of 10% committed by the licensee, is authorized pursuant to 10 CFR 50.55a(a)(3)(1).

4 The use of this attemative is authorized for the current interval at Byron Units 1 and 2, or until Code Case N-50g is approved for general use by reference in RG 1.147. After that time, the leoensee must follow the conditions, if any, specified in the regulatory guide.

Request for Relief No.12R-18: Section XI, Table IWB 2500-1, Examination Category B-D, items B3.90 and 83.100 require that, for reactor pressure vessel (RPV) nozzle welds and inner radius sections, at least 25% but not more than 50% (credited) of the noules shall be examined by the

. end of the first inspection period and the remainder by the end of the inspection interval.

Examination Category B-F, item B5.10, Note (1) states that the reactor vessel noule-to safe end

- weld examinations may be performed with the vessel nouie examinations.

4

' Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee has proposed to use Code Case N-521 as an

attemative to the Code requirement to examine at least 25% of the vessel-to noule welds and noule inner radius sections during the first examination period. All of the RPV nozzle-to vessel welds, the noule inside radius sections, and the nozzle-to safe end welds will be examined -

13 J

i.

_ _ _ _ _ _ . _ _ _ _ . . _ .. _.-.L__,

. , _ . . _ . . . . _, _ _ . . - . . _ . . _ . , . . , _ . . , , . ,. , , , ,e . ~ _ _. ,._.. _ _ - . , . , _ , - -

concurrently with the reactor vessel ten-year examinations at or near the end of the second 10-year inspection interval. Scheduling will be such that no more than 10 years will occur between these examinations, except when the length of a 10-year intervalis adjusted in I accordance ydth IWA-2430. The welds and examination areas are listed below.

l l

Nonie-to-Vessel (Item inside Radius Sections Nonle-to Safe End Welds  ;

B3.90) (item B3.100) (item B5.10)  !

Unit 1 Unit 2 Unit 1 Unit 2 Unit 1 Unit 2 RPVN-A RPVN A RPVN-A NIR RPVN-A-NIR F1/RPVS A* F1/RPVS A RPVN-B RPVN-B RPVN-B-NIR RPVN-B-NIR F1/RPVS-B F1/RPVS-B RPVN-C RPVN-C RPVN-C NIR RPVN-C-NIR F1/RPVS-C F1/RPVS-C RPVN-D RPVN-D RPVN-D-NIR RPVN-D-NIR F1/RPVS-D* F1/RPVS-D RPVN-E RPVN-E RPVN-E NIR RPVN-E NIR F1/RPVS E' F1/RPVS-E RPVN-F RPVN F RPVN-F-NIR RPVN-F-NIR F1/RPVS F F1/RPVS F RPVN-G RPVN-G RPVN-G-NIR RPVN-G-N!R F1/RPVS-G F1/RPVS-G RPVN H RPVN-H RPVN-H.NIR RPVN-H NIR F1/RPVS-H* F1/RPVS-H

• Surface examinations performed in Period 1 of Interval 1. Interval 2 surface examinations will be performed in Period 1 of Interval 2.

The Code requires the examination of at least 25%, but not more than 50% of RPV nonles and associated inside radius (IR) sections and nonle safe ends during the first inspection interval.

The licensee has requested authorization to use Code Case N 521 and defer exemination of these areas until the end of the second 10-year interval.

Code Case N 521 states that examination of RPV nonles, IR sections, and nonle to-safe end welds may be deferred provided (a) no inservice repairs or replacements by welding have ever ueen performed on any of the subject areas, (b) none of the tubject areas contain identified flaws or relevant conditions that currently require successive inspections in accordance with IWB-2420(b), and (c) the unit is not in the first interval.

The licensee has confirmed that the above conditions have been met. In addition, the licensee has volumetrically examined all the subject areas during the third period of the first 10-year interval. By examining the nonle-to-vessel welds, and associated IR sections and noule-to-safe end welds, at the end of the first 10-year interval, the licensee has established a new sequence I

of examinations that will not exceed 10 years between inspections as noted in IWA-2430.

Because the licensee repeated the examinations at the end of the previous interval and will meet the conditions necessary for application of the Code Case, the licensee's proposal to use Code Case N-521 as an attemative to the Code provides an acceptable level of quality and safety since the maximum time of 10 years between inspections will not be exceeded as noted in lWA-2430. Therefore, the licensee's proposed attemative is authorized pursuant to 10 CFR 50.55a(a)(3)(i).

3.0 CONCLUSION

S The staff has reviewed th9 licensoe's submittals and concludes that for Requests for Relief 12R-05,12R-06,12R-07,12R-08,12R 10,12R-13,12R-15,12R-16,12R-17, and 12R 18, the license: 'roposed attematives to the Code requirements provide an acceptable level of qunht) and safety. Therefore, licensee's proposed attematives contained in the above requests for relief 14

_ , . - _ ___ - * -e_

are authorized pursuant to 10 CFR 50.55a(s)(3)(i). For Request for Relief 12R 11 Revision 1, the staff concluded that the licensee's proposed ahomative provides an acceptable level nf quality and safety for Class 1 systems. Therefore, the licensee's proposed aMemative is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for Class 1 systems ontv. The licensee's proposed anomative for Class 2 and 3 systems is denied.

For Request for Relief 12R 09, the staff concluded that the Code requirements are impractical for the subject welds and relief is granted pursuant to 10 CFR 50.55a(g)(6)(i). In granting the request for Reliof 12R-09 the staff concluded that the relief is authorized by law and will not endar.ger lifs or property or the common defense and security and is otherwise in the public interest given due consideration to the burden upon the licensee that could resuN if the requirements were imposed on the facility.

Attachment:

Technical Letter Report Principle Contributors: T. McLellan F. Grubelich Dated: January 13, 1998

}

15 1

TECHNICAL LETTER REPORT

• ON THE SECOND 10-YEAR INTERVAL INSERVICE INSPECTION  :

REQUESTS FOR RELIEF fQB COMONWEALIREDtSQhLCOMPlhtY 4

BYRON NUCLEAR POWER STATION. UNITS 1 AND 2 DOCKET NUMBERS: 60454 AND 50455 l

1.0 INTRODUCTION

By letter dated February 23,1996, the licensee, Commonwealth Edison Company, submitted its second 10-year inservice inspection (ISI) program for Byron Nuclear Power Blation, Units 1 and

2. Additional information was submitted in August 12,1996, and December 16,1996, in response to Nuclear Regulatory Commission (NRC) requests for additional information (RAls).

! ' The licensee asked that the review of certain requests for relief be expedited for implementation in en upcoming outage. The Idaho National Engineering and Environmental Laboratory (INEEL) staff has evaluated the information provided by the licensee in support of these requests for relief in the following section.

2.0 EVALUATION The Code of record for the Byron Nuclear Power Station, Units 1 and 2, second 10-year inservice inspection interval is the 1989 Edition of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. The information provided by the licensee in support of the requests for relief has been evaluated and the bases for disposition are documented below.

A. Reauest for Relief No.12R-05 (Revision 2). Examination Cateoory C-B. Item C2.32. Residual Heat Removal Heat Exchanaer (RHRHX) Ncule to-Shell Weld Code Reauirement: Section XI, Table IWC-25001, Examination Category C-8, item C2.32,

- requires a volumetric examination as defined by Figure IWC 2500-4(c). This examination is specified for nonle-to-shell (or head) welds with reinforcing plates in vessels greater than Winch nominal thickness when the inside of the vessel is accessible for nonle examinations. Examinations are limited to noules at terminal ends of piping runs selected for examination under Examination Category C-F.

ATTACHMENT

c *  !

. i l

l l

I- Ucensee's Proposed Allemative: Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposes ')

l

to perform a best effort ultrasonic examination of RHRHX noule-to vessel Welds RHXN-01 l and RHXN-02 for Units 1 and 2, respectively. Additionally, a surface examination will be  !

i performed on each noule in each inspection period during the second inspection interval. i Uconsee's Basis for Proposed Altemative (as stated):-

)

. " Pursuant to 10 CFR 50.55a(s)(3)(i), relief is requested on the basis that the proposed alternatives provide an acceptable level of quality and safety.

i

' 'The Residual Heat Removal Heat Exchangers were fabricated with a shell nominal wall thickness of .875 inch and 14 inch diameter inlet and outlet noules which are .375 nominal ,

well thickness. The noules were attached to the shell by a double bevel groove weld and

reinforced on the O. D. by a fillet wold, as well as by a fillet welded pad on the I.D., as shown in Figure 1.8 The configuration is similar to that shown in Figure IWC-2500-4(c),

except for intomal location of the reinforcing pad. Because the inlet and outlet piping is wolded to the subject noulos, the inside of the RHR Heat Exchangers is not accessible as 4 described in the ' Parts Examined' text for item No. C2.32.

"Due to the geometrical constraints of the noule design, the ultrasonic examination of

- noule-to-vessel welds will not achieve the required 90% coverage per Code Case N-460 and Section XI,1969 Edition. Altematively, a 'best effort' ultrasonic examination will be performed on one sample noule-to-vessel weld of each unit during the first period and a dye penetrant examination on each noule in each period for the ten-year interval. This attemative examination approach was approved for Interval 1 per NRC Safety Evaluation 3

Report dated February 29,1996 for Relief Request NR-18.

"The 'best effort' ultrasonic examination will primarily be performed from the noule outside surface. Anticipated obstructions include the reinforcement fillet weld located directly above the noule-to vestel weld. This fillet weld restricts inspection transducer movement and limits availehle examination angles. A 70' transducer will be used on the noule side of the weld to pass sound under the fillet weld to reach the lower 1/3T of the pressure retaining d

.wold. Scanning from the vessel side of the weld will be accomplished by use of a 45' shear wave transducer on the shell surface to reach the examination volume. These scans are h the axial direction of the noule to-vessel weld. Scans in the circumferential direction will be very limited due to the location of the fillet weld. This weld location does not allow the -

transducer to scan over the entire examination volume from the outside of the noule. - it is

- estimated that 99,92% of the examination volume will be reached in the axial direction. With limited circumferential scans (13.29%), the total scanning percentage is estimated at 56.61 %.

"In addition, a VT-2 examination during system pressure testing per Category C-H is also posformed on the Residues Heat Removal Heat Exchangers each inspection period to verify leaktight integrity of these welds. Based on this information, reasonable assurance of the continued inservice structural integrity of the subject welds is achieved without performing a -

1

-included in licensee's submittal, but not included in this report.

2-

complete Code examination. Compliance with the applicable Code requirements can only be accomplished by redesigning and refabricating the Residual Heat Removal Heat Exchangers. Byron Station deems this course of action a hardship without a compensating increase in the level of quality and safety "

gralgalign: The Code requires 100% volumetric examination for the subject RHRHX nozzle-to-shell welds, in lieu of Code-required volumetric examination, the !!censee has proposed to perform a best-effort ultrasonic examination on one of the two nozzles in each plant and a surface examination on each nozzle each inspection period during the second 10-year interval.

The fillet weld configuration makes ultrasonic examination of the subject welds difficult to perform to the extent required by the Code. Even with this difficult configuration, the licensee can complete an estimated 55.6% of the Code-required volumatric examination for each of the welds. In addition to the best effort ultrasonic examination, the licensae will perform surface examinations on the nozzles once each period. The best-effort ultrasonic examination, in combination with the surface examination each inspection period, should detect any existing pattoms of degradation and will provide an acceptable level of quality and safety. Therefore, it is recommended that the licensee's proposed altemative be authorized pursuant to 10 CFR 50.55a(a)(3)(i).

B. Reauest for Relief No.12R-06. Examination Cateaory C-C. Item C3.30. Inteorally Welded Attachments to Pumos Code Reauirement: Section XI, Twbie IWC-2500-1, Examination Category C-C, item C3.30, requires 100% surface examination as defined by Figure IWC-2500-5 for integrally welded attachments to pumps. Examinations are limited to attachment welds to components examined under Examination Categories C-F and C-G.

Licensee's Proposed Attemative: Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed an attomative to the Coderequired surface examination of integrally welded attachments to 3-

e l

l l

the contrifugal charging pumps and residual heat removal (RHR) pumps; these attachments are:

. CVPE-01 CVPE-02 CVPE-03 CVPE 04 L RHPE-01 RHPE-02 RHPE-03 RHPE-04 i The licensee stated:

"A Visual, VT-1 examination will be performed on the portions of the subject welds which are inaccessit lo. The Code required surface examination will be performed on the accessible portions of the subject welds."

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

[

" Pursuant to 10 CFR 50.55a(s)(3)(l), relief is requested on the basis that the proposed attematives provide an acceptable level of quality and safety.

'Due to the design of the Centrifugal Charging Pump and Residual Heat Removal Pump support lugs, portions of the associated integral attachment welds are inaccessible for code required surface examination. The inaccessible areas are shown in Figures 1 and 2.8 As detailed in these Figures, the portion of the subject weld within the recess between the pumps and the support lugs does not provide sufficient clearance to perform a surface examination. l l

"Because the subject welds are not full penetration welds, performance of the altemative

Visual VT-1 examination on the inaccessible weld length will provide satisfactory assurance  ;

of the structuralintegrity of these welds. l i

• Based on this information, reasonable assurance of the continued inservice structural I integrity of the subject welds is achieved without performing a complete Code examination.

In addition, a VT-2 examination during system pressure testing per Category C-H is also perforrt.ed on the Centrifugal Charging Pumps and Residual Heat Removal Pumps each inspection period to verify leaktight integrity of these components. Compliance with the applicable Code requirements can only be accomplished by redesigning and refabricating the Centrifugal Charging Pumps and Residual Heat Removal Pumps. Byron Station deems this course of action a hardship without a compensating increase in the level of quality and safety."

- Evaluation The Code requires 100% surface examination of the subject integral attachment l welds. However, portions of the welds are located between the pump emi the concrete support, making them inaccessible for surface examination. In lieu of the Code-required,

1. I 100% surface examination, the licensee will perform the surface examination on the accessible portions of the welds and a VT-1 visual examination on the inaccessible portions.

-Included in licensee's submittal, but not included in this report.

. -4

e s

l The licensee's proposed aNemative, to visually examine portions of the subject integral attachment wolds that are inaccessible for surface examination, in combination with the Code-required surface examination of the accessible portions, will detect any significant

pWoms of degradation that could affect the structural integrity of the integral attachments.

Since the entire length of each wold will be examud ither surface or visual examination-the licensee's altomative will provide an acceptable level of quality and safety.

Therefore, it is recommended that the licensee's proposed altemative be authorized pursuant to 10 CFR 50.55a(a)(3)(i).

C. Reauest for Relief No.12R-07. Examination Cateoorles C F-1 and C-F-2. Items C5.11N.

C5.12N. C5.51N and C5.52N. Class 2 Pinina Welds Note: The licensee is using Code Case N-408 2, Altomatim Rules for Exam / nation of Class 2 Piping, Section X/, Division 1, in lieu of the requirements of the Code for the examination of Class 2 piping welds. Code Case N-40-2 has been approved for general use by reference in Regulatory Guide 1.147, Inservice Inspection Code Case Acceptability, ASME Section XI, DMalon 1, Code Case Reouirement Code Case N-408-2, Tables 1 and 2, Examination Categories C F-1 and C-F-2, items C5.11N, C5.12N, C5.51N and C5.52N,7 requires volumetric and surface examination as defined by Figure IWC-2500 7 (of the Winter 1983 Addenda) for piping welds greater than or equal to 3/8 inch nominal thickness and greater than 4-inch nominal pipe size (NPS).

Licensee's Proposed Altemative: Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed to include Class 2 piping welds less than 3/8 inch thick but greater than 1/4-inch nominal thickness in the 7.5% volumetric and surface examination sample. Specifically, the licensee stated:

" Byron Station will select for examination nonexempt, Code Class 2 piping welds per Code Case N-408-2, Tables 1 and 2 Note (2) without eliminating welds with nominal wall thickness less than .375 inch from consideration. The welds selected which are nominal wall thickness less than .375 inch would be volumetrically and surface examined per the

-The letter "N" designates piping welds less than 3/8-inch noininal wall thickness.

5-

La-1

.=

requirements of Code Case N.406 2, category C-F-1, Hem Nos. C5.11 and C5.12 and Category C-F 2, item Nos. C5.51 and C5.52. Wolds with Nominal WaN Thickness less than

.250 inch well will not be included as part of this altamative selection methodology."

Ucensee's Basis for Proposed ANemative (as stated):

" Pursuant to 10 CFR 50.55a(a)(3)(i), relief is twquested on the basis that the proposed allematives provide an acceptable level of quality and safety.

f "The attemative rules included in Code Case N-406 2, (approved for use in Regulatory Guide 1.147, Revision 11), for selection and examination of nonexempt Code Class 2 piping welds were developed in recognition of the approximately 30 years of industry experience in the application of nondestructive examination techniques. The empirical data provided to the ASME Section XI Subcommittee and associate Working Groups and Task Groups indicated that meaningful ultrasonic (UT) examination could nct be performed on piping with a nominal well thickness less than .375 inch.

"The impact of employing this .375 inch nominal wall thickness " threshold" is that the m$,,iti of the nonexempt piping welds within Code Class 2 systems are excluded from the Section XI nondestructive examinations. This piping is typically 6 inch, 8 inch or 10 inch schedule 40 or Standard well piping. Examination on the low pressure and pump suction .

piping, designed as schedule 40 or standard wall would not be required until Nominal Pipe  :

. Size 12 inch is reached. The methodology in Note (2) of Tables 1 and 2 only requires that l these welds be included in the ' total we d count'. Surveys of other nuclear planta indicate  !

that the percentage of the welds within nonexempt Code Class 2 systems which are less )

than .375 inch nominal wall thickness comprise 50% or more of the overall nonexempt 1 system welds. l "The piping at Byron Station which is less than .375 inch nominal wall thickness is identified

. on the Classification Boundary Drawings in Appendices C and F of this submittal with Category C-F-1 and item No. C5.11N and Category C-F-2 and item No. C5.51N. Actual weld totals for Byron Units 1 and 2 indicate that 40% of the total nonexempt, circumferential wolds (excluding High Pressure Safety injection welds) are in piping which is less than .375 Nominal Wall Thickness. For stainless steel welds (Category C F-1), these welds comprise greater than 60% of the totalwelds. l

" Commonwealth Edison's experience in performing ultrasonic (UT) examinations per ASME Section XI is that a meaningful UT exam can be performed on piping with wall thickness as 4 smaN as .250 inch Specific experience at Byron Station on Code Class 2 piping welds within systems that perform CHR, ECC, and RHR functions supports this contention.

"Because these ' thin waN welds' make up such a large segment of the overall nonexempt weld population, their elimination may remove the ability of cn owner to sample by i volumetric examination a significant group of wolds which experience sornewhat unique l operatior el characteristics (i.e. Iow pressure, lower flow rates, stagnant borated fluid, etc).

- Viewed in this light, the exclusion of the welds from the Section XI NDE program appears contrary to the overaN philosophy of Section XI to provide a continuing assurance that components in a nuclear power plant are safe and establish a baseline condition of a 4

component so that the potential degradation can be monitored.

d

___-_____.I. m m____. .m._._ , , . .. ,,. ,,., .m_ . _ ,, ,._ ,, ,_. . _ . , _ . , . , ,,m - __,_ _, ..,. . . , ,

"The first interval ISI Program at Byron Station includes augmented requirements for volumetric examination of many of these thin wall welds. The volumetric examinations were successfully completed and established a baseline record for these welds. Development of the second interval ISI per Code Case N-408-2 incorporated all these welds into the Section XI ISI Program; however, Note (2) of Tables 1 and 2 eliminates these welds from examination consideration. It is Byron Station's position that the rules in Code Case N-408-2 which exclude Code Class 2 piping welds with nominal well thickness less than .375 inch are art >ltrary and do not acknowledge the ability of current ultrasonic equipment and techniques to provide meaningful data. Further, the Code Case N-408 2 rules are art itrary in that they do not allow an owner the ability to sample, within their Section XI ISI/NDE Program, a true cross section (i.e., across all operational conditions, wall thickness, design, etc) of the Code Class 2, nonexempt weld population.

"The application of Code Case N-408-2 rules at Byron Station for the second interval will eliminate any immediate or future safety benefit (e.g. identification of a potential failure) that Comed might realize from the first interval examination of these thin wall welds, These rules also eliminate the ability of Comed to realize any retum on the monetary investment (the cost of manpower and radiation exposure) incurred for the first interval examinations.

"Accordingly, Byron Station requests relief from these rules on the basis that the proposed altemative would provide an acceptable level of quality and safety. The altemative rules presented below would allow Comed Byron Station to attematively select for examination nonexempt, Code Class 2 piping welds per Code Case N-408-2, Tables 1 and 2 Note (2) without eliminating welds which are nominal wall thickness less than .375 inch from consideration. The welds selected which are nominal wall thickness less than .375 inch would be volumetrically and surface examined per the requirements of Code Case N-408-2, Categories C-F-1, item Nos. C5.11 and C5.12 and Category C-F-2, item Nos. C5.51 and C5.52."

Evaluation: Code Case N-408 2 requires volumetric and surface examination of a 7.5%

sample of piping welds greater than or equal to 3/8-inch nominal thickness and greater than 4-inch nominal pipe size (NPS). Welds less than 3/8 inch nominal wall thickness are included in the population but excluded from examination. Code Case N-408-2 has been approved for used by incorporation in Revision 11 of Regulatory Guide 1.147, inservice Inspection Code Case Acceptability, ASME Section XI, Division 1. The licensee's experience indicates that meaningful UT examinations can be performed on piping welds as small as 1/4-inch thick. Therefore, the licensee has proposed to use sampling criteria that do not exclude thin-walled piping in the Residual Heat Removal (RHR), Emergency Core Cooling (ECC), and Containment Heat Removal (CHR) from volumetric and surface examinations. The proposed change reduces the number of examinations on piping welds greater than 3/8-inch but does not affect the overall examination sample size for Class 2 piping welds since piping welds less than 3/8-inch will now be included in the examination sample.

7

- 4 ,

1 t

'The first interval ISI Program at Byron Station includes augmented requirements for

volumetric examination of many of these thin wall welds. The volumetric examinations were successfully completed and established a baseline record for these welds. Development of the second interval ISI per Code Case N408-2 incorporated all these welds into the Sechon XI ISI Program; however, Note (2) of Tables 1 and 2 eliminates these wolds from examination consideration, it is Byron Station's position that the rules in Code Case N-408 2 l which exclude Code Class 2 piping welds with nominal wall thickness less than .375 inch are art >ltrary and do not acknowledge the ability of current ultrasonic equipment and techniques to provide meaningful data. Further, the Code Case N-408-2 rules are arbitrary in that they do not allow an owner the ability to sample, within their Section XI ISI/NDE Program, a true cross section (i.e., across all operational conditions, wall thickness, design, etc) of the Code Class 2, nonexempt weld population.

'The application of Code Case N-408 2 rules at Byron Station for the second interval will eliminate any immediate or future safety benefit (e.g. identification of a potential failure) that Comed might realize from the first interval examination of these thin wall welds. These rules also eliminate the ability of Comed to realize any retum on the monetary investment (the cost of manpower and radiation exposure) incurred for the first interval examinations.

"Accordingly, Byron Station requests relief from these rules on the basis that the proposed attemative would provide an acceptable level of quality and safety. The attemative rules presented below would allow Comed Byron Station to altematively select for examination nonexempt, Code Class 2 piping welds per Code Case N-408-2, Tables 1 and 2 Note (2) without eliminating welds which are nominal wall thickness less than .375 inch from consideration. The welds selected which are nominal wall thickness less than .375 inch would be volumetrically and surface examined per the requirements of Code Case N-408-2, Categories C-F-1, item Nos. C5.11 and C5.12 and Category C-F 2, item Nos. C5.51 and C5.52."

1

. Evaluation: Code Case N-408-2 requires volumetric and surface examination of a 7.5%

sample of piping welds greater than or equal to 3/8-inch nominal thickness and greater than 4-inch nominal pipe size (NPS). Welds less than 3/8-inch nominal wall thickness are included in the population but excluded from examination. Code Case N408-2 has been L approved for used by incorporation in Revision 11 of Regulatory Guide 1.147, /nservice 5 Inspection Code Case Acceptability, ASME Section XI, Division 1. The licensee's experience indicates that meaningful UT examinations can be performed on piping welds as i small as 1/4-inch thick. Therefore, the licensee has proposed to use sampling criteria that do not exclude thin-walled piping in the Residual Heat Removal (RHR), Emergency Core b Cooling (ECC), and Containment Heat Removal (CHR) from volumetric and surface examinations. The proposed change reduces the number of examinations on piping welds greater than 3/8-inch but does not affect the overall examination sample size for Class 2 piping welds since piping welds less than 3/8-inch will now be included in the examination sample.

- 7-l

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The INEEL staff concurs with the licensee's position and believes that it is technically prudent to examine a representative sample of thin-walled piping wolds in the RHR, ECC, and CHR systems. This can be accomplished by either augmenting the examination sample or by substituting thin-walled welds for thick walled welds. The licensee has opted to substitute thin-walled Class 2 piping, Since the licensee has not reduced the overall examination sample, this attemative provides an acceptable level of quality and safety.

Therefore, it is recommended that the licensee's attemative be authorized pursuant to 10 CFR 50.55a(a)(3)(i).

D. Reauest for Relief No.12R-08. Examination Cateoory C-F-1 and C-F 2. Item C512. C5J2ft C5.52 and C5 52N. Class 2 Lonoitudinal Pipino Welds Code Reauirement: Section XI, Table IWC-2500-1, Examination Category C-F-1 and C-F 2, items C5.12 C5.12N, C5.52 and C5.52N require 100% surface and volumetric examination, as defined by Figure IWC-2500-7, for 2.5T of longitudinal piping welds from intersecting circumferential welds.

Licensee's Proposed Attemative Examination: Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee has proposed attemative scan coverage requirements in lieu of the volumetric and surface examination coverage requirements of the Code for Class 2 longitudinal welds.

Specifically, the licensee stated:

" Surface and volumetric examinations shall be performed, as applicable, on the length of the longitudinal weld that is normally examined during examination of the intersecting circumferential welds (s). The volumetric examination at the intersection of circumferential and longitudinal welds will include both transverse and parallel scans within the length of the longitudinal weld that falls within the circumferential weld examination boundary."

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

l

' Pursuant to 10 CFR 50.55a(a)(3)(i), relief is requested on the basis that the proposed 4 attematives provide an acceptable level of quality and safety.

" Based on the following discussion, the performance of surface and volumetric examination on longitudinal piping welds has a negligible compensating effect on the quality or safety of Class 2 piping. In addition, there is little, if any, technical benefit associated with the performance of these examinations, but they result in a substantialinan-rem exposure and cost.

1) Throughout the nuclear industry, there has been no evidence of rejectable service induced flaws being attributed to longitudinal piping welds,

2) During the first inservice inspection interval at the Byron Station, no inservice flaws have been detected in longitudinal piping wolds.

3) There are distinct differences between the processes used in the manufacturing of longitudinal and circumferential wolds which enhance the integrity of longitudinal wolds.

First, longitudinal wolds are typically manufactured under controlled shop conditions whereas circumferential wolds are produced in the field under less ideal conditions, Secondly, longitudinal welds usually undergo heat treatment in the shop which

j. Improves their material properties and relieves the residual stresses created by welding.

Finalif, shop manufacturing inspections can be performed under more favorable conditions which further increase the confidence level of the longitudinal weld quality.

4) During field installatim of piping, the ends of the longitudinal welds may be affected during welding of the intersecting circumferential field wolds, This smail area falls within the circumferential weld inspection boundaries. Therefore, the ends of the longitudinal welds will still be subject to examination.

5) From an industry-wide standpoint, there has been no evidence of longitudinal weld defects compromising safety at nuclear generating facilities.

6) No significant loading conditions or known material degradation mechanisms have 4

become evident to date which specifically relate to longitudinal seam welds in nuclear plant piping.

l 7) There is a significant accumulation of man-rom exposure and cost associated with the inspection of Class 2 longitudinal piping welds.

i

, 8) The attemative examinations proposed below provide an acceptable level of quality and safety without causing undue hardship or difficulties."

l Evaluation: ASME Section XI requires the examination of one pipe diameter, but not more i-,

than 12 inches, of Class i longitudinal piping welds. For Class 2 piping welds, the length of longitudinal weld required to be examined is 2.5 times the p!pe thickness, These lengths are measured from the intersection with the circumferential weld. The liconeee's proposed

! altemative is to examine only the portions of longitudinal weld contained wi+.hin the examination area of the intersecting circumferential weld. This altomative is contained in Code Case N-524, Attemative Examination Requirements for Longitudinal Welds in Class 1 and Class 2 Piping, which has previously been found acceptable for use at other facilities.

l Longitudinal welds are produced during the manufacture of the piping, not in the field as circumferential welds are. Consequently, the welds are fabricated under the strict guidelines

.g.

l L

. .- I s

3 i

- g+1d by the manufacturing standard, which provides assurance of structuralintegrity.

These wolds have else been subjected to the preservice and initial inservice examinations, which provide additional assurance of structuralintegetty. No signirmant loading conditions  ;

or material degradation mechanisms have become evident to date that specifically %de to longitudmal seem welds in nuclear plant piping. The most critical region of the longitudinal l weld is the portion that intersects the circumferential wold. Since this region will be - l

. examined during the examination of the circumferential wold, the licensee's altemative provides an acceptable level of quality and safety. Therefore, it is recommended that the licensee's proposed altemotive be authorized pursuant to 10 CFR 50.55a(s)(3)(i).

4 E. Begypst for Relief No.12R-09. Examination Cateoories C-F-1 and C F-2. Items C5.41 and C5.81. Circumferential Branch Connection Weldt Code Reauirement: Section XI, Table IWC-2500-1, Examination Categories C F-1 and C-F-2, items C5.41 and C5.81 require 100% surface examination as defined by Figures IWC-2500-g to 13 inclusive, for circumferential branch connection welds in branch piping greater

~ than or equal to 2-inch nominal pipe size (NPS).

Licensee's Code Relief Reauest Pursuant to 10 CFR 50.55a(a)(5)(iii), relief is requested from performing the Code-required surface examination of the 6-inch main steam relief valve line branch connections and the 16-inch residual heat removal piping to 24-inch safety injection piping branch connections listed in the table below.

4 4

4 4

i

Table 12R 09 Unit Exam. Cat. Item Line No. Weld Numbers 1 C-F 1 C5.41 18106BA 24 C18 1Sl06BB-24 C24 C-F 2 C5.81 IMS07BA 28 CO3,C04,COS,C09,C10 IMS07BB-28 C03,C04,COS,C06,C10 IMS07BC-28 C03,C04,COS,C06,C07 IMS07BD 28 CO3, C04, COS, C09, C10 2 C-F-1 C5.41 2SIO6BA 24 C26 2Sl06BB-24 C26 C-F 2 C5.81 2MS07AA-28 C12,C13,C14,C15,C16 2MS07AB-28 C15,C16,C17,C18,C19 2MS07AC-28 C15,C16,C17,C18,C19 2MS07AD-28 C12,C13 C14,C15,C16 Licensee's Basis for Reauestina Relief (as stated):

' Pursuant to 10 CFR 50.55a(a)(5)(iii), relief is requested on the basis that conformance with the Code requirements is impractical.

"The design of certain branch connection welds calls for te u. ' of reinforcement saddles.

These saddles are fillet welded over the pressure retaining un.n.cn pipe to main pipe, completely encasing it as illustrated in Figure 1.* This design precludes any type of surface or volumetric examination from being performed on the pressure retaining branch connection weld. Assurance of the continued integrity of these joints is afforded by the fact that the reinforcement saddle strengthens the joint and reduces the stresses on the obstructed branch to pipe weld.

" Based on the above, Byron Station requests relief from the ASME Section XI requirements

! for the surface examination of Class 2 branch connection welds that are designed with a l reinforcement saddle."

l l

l 1

-Contained in licensee's submittal but not included in this report.

Licensee's Proposed Allemative Examination (as stated):

' 'As an altomative examination, Byron Station will perform a surface examination of the i anddle to main pipe wold and the saddle to branch pipe wold, when the pressure retaining -

weld b made inaccessible due to the use of a reinforcement saddle. Additionally, a VT 2 visual examination of these areas will be performed in conjunction with the required Class 2 System Pressure Tests."

Evaluation:- The Code requires a 100% surface examination of each of the subject branch connection wolds. However, access to these welds is completely obstmeted by rolnforcing anddle plates that are fillet welded over the pressure-retaining branch connection welds.

Therefore, the design makes the Code requirements impractical for these branch connections. To gain access for examination, the saddle plates would have to be removed and the branch connections redesigned and modified. Imposition of this requirement would create a considerable burden on the licensee, in lieu of the Code-required surface examination, the licensee will perform a surface examination of the fillet welds used to attach the saddle plate to the main pipe and branch pipe. Examination of these welds will detect any gross structural deformation and confirm the overall integrity of the branch connection. In addition, the licensee will perform VT-2 visual examinations of these areas in conjunction with the Class 2 pressure tests. As depicted in the licensee's attached figure, each of the saddle plates includes a telltale hole.

Any leakage that could occur from the inaccessible pressure-retaining weld would be detector during the Class 2 pressure tests. The INEEL staff concludes that the attomate surface examination, along with the Code-required pressure tests, will ensure the structural integrity of the subject branch connections. Therefore, considering the impracticality of the Code requirements for the subject welds and the assurances provided by the altomative surface examination and Code-required pressure tests, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).

F. Reauest for Relief No.12R-10. Examination Cateoorv C-H. Items C7.30. C7.40. C7.70 add C7.80. Pressure Testina of Containment Penetration Pipino Attached to Non-Classed Pioino

- Code Reauirement Section XI, Table IWC-2500-1, Examination Category C-H. Items 4

C7.30, C7.40, C7.70 and C7.80 require a system leakage test at operating pressure for pressure-retaining piping and valves.

+ , , , - - ,, , , , , ~ -- ,,v- a -- - - - ., , . -,~-, --- -

2

. t Licensee's Proposed Allemative: Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed to perform 10 CFR 50, Appendix J leakage tests as an altemative to the Code-required pressure tests for containment penetration piping with attached non-classed piping. -The leakage tests will be performed at no less than the peak calculated containment pressure (44.4 psig) as defined in the Byron Technical Specifications and Byron Station will implement station VT surveillances to detect and locate extemal piping leakage.

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

• Pursuant to 10 CFR 50.55a(a)(3)(i), relief is request on the basis that the proposed attemative would provide an acceptable level of quality and safety.

" Spec'fically, Byron Station requests relief from the requirement to perform a pressure test in accordan::e with ASME Section XI, Table IWC 25001, Examination Category C-H on the Code Class 2 lines listed above.

"The primary reactor containment integrity, including all containment penetrations, is periodically verified by performing leakage tests in a::cordance with a 10 CFR 50, Appendix J. Each of the Code Class 2 lines and their associated isolation valves are tested during an i Appendix J, Type A, B, or C leakage test at a pressure not less than 44.4 psig. The Type A leakage test is performed at intervals not greater than 24 months. Performance of these l Appendix J leak tests will verify the integrity of the subject Code Class 2 lines at each I respective penetration. The performance of ASME Section XI, Examination Categ)ry C-H I pressure tests on these same lines will provide little, if any, additional verification of primary reactor containment integrity and are thus redundant tests.

l *Per the preceding information, Byron Station requests relief from the ASME Section XI requirements for pressure testing these Code Class 2 containment penetration components

, . on the basis that Proposed Altemate Provisions provide an adequate level of quality and i safety."

l l Evaluation

• The Code requires that a VT-2 visual examination be performed during system pressure testing for Class 2 pressure-retaining piping. As an altemative, the licensee proposes to implement the requirements of 10 CFR 50, Appendix J for the subject piping.

This altemative is contained in ASME Code Case N-522, Pressure Testing of Containment-

Penetretion Piping, which has previoush been found acceptable for use at other facilities with certain conditions, i

L The subject piping is classified as Class 2 because it penetrates primary reactor

containment and la considered an extension of the containment vessel. Since the piping on either side of these penetrations is non-classed, the requirements of Appendix J are more

.. _ .u. , . __ _ _ _ _ . _ _ . _ _ _ -__ __. _ _ _ _ . _ _ _ ._

.- t b

appropriate than those of Examination Category C-H. Appendix J pressure tests verify the leak tight integrity of the primary reactor containment and of systems and components that 4 penetrate containment by localleak rate and integrated leak rate tests, in Appendix J pressure tests, containment isolation valves and connecting pipe segments must withstand 4

the peak calculated containment intemal pressure related to the maximum design -

containment. In addition, the NRC staff has determined that the Appendix J test frequencies are acceptable for assuring containment integrity. Therefore, use of Appendix J should be considered acceptable for the subject penetration piping.

The licensee has committed to perform the Appendix J testing at no less than the peak calculated containment pressure and will use station VT surveillances to detect and locate i

the source of the leakage. The INEEL staff believes that an acceptable level of quality and safety will be provided by the licensee's proposed altemative since it will test the subject penetrations for their intended function. Therefore, it is recommended that the licensee's proposed attemative pressure test be authorized pursuant to 10 CFR 50.55a(a)(3)(i).

G. Reauest for Relief No.12R 11 (Revision 1). Paraaraoh IWA 5242(a). VT-2 Visual Examination of Insulated Comoonqnta Code Reauiremont- lWA 5242(a) requires that insulation shall be removed from pressure-retaining bolted connections for VT-2 visual examination in systems borated for the purpose of controlling reactivity.

Licensee's Proposed Attemative: Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee has proposed the following attemative to the Code requirement to remove insulation at bolted connections for VT-2 examination during system pressure testing (as stated).

"For systems borated for the purpose of controlling reactivity, a system pressure test of inservice leakage test shall be performed in accordance with the frequency required in tables IWX-2500 without the removal of insulation from the bolted connections.

2 "A minimum 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> hold time prior to the VT-2 visual examination shall be invoked to allow for leakage propagation from the insulation.

" Additionally, the insulation shall be remos ad from these bolted connections and a VT-2 l examination shall be conducted. During this VT-2 examination, the bolted connections are not required to be pressurized. The frequency for these inspections shall be in accordance

c ..

-s

!i '

with the system examination frequencies specified in Tables lWX 2500, Categories B-P (each refueling outage), C-H (each period), and D-A (each period).

"Any evidence of leakage, eitner while insulated or while deinsulated, will result in evaluations for corrective measures in accordance with IWB 5250 (as modified for Byron Station by approved Relief Request 12R 12').* ]

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

" Pursuant to 10 CFR 50.55e(s)(3)(i), relief is requasted on the basis that the proposed altomotive would provide an acceptable level of q ality and safety. Specifically, relief is requested from the requirement to remove insulation at bolted connections for VT-2.

examination during system pressure testing for the following reasons:

1. Code Class 1,2 and 3 systems borated for the purpose cf controllino reactivity are extensive and large systems covering many areas and elevations, ficaffolding will be required to access many of the bolted connections. In addition, many of the bolted connections are located in difficult to access areas and in medium to high radiation  ;

areas, insulation removal combined with scaffolding requirements will increase the financial cost, personnel exposure, and generation of radweste associated with performance of VT-2 examinations.

l 2. The VT 2 examination of Class 1 systems, primarily the Reactor Coolant System (RCS)

piping and components, is performed at plant mode 3. As required by IWB 5221, the

+

RCS is at a nominal operating pressure of 2235 psig. At mode 3 the temperature is i approximately 557'F. Removal / reinstallation of insulation for class 2 and 3 systems similarty pose significant safety and radiological problems. These systems are in

! support of reactor shutdown and generally are operational when the RCS is at pressure and temperature associated with 100% reactor power. Performance of a VT 2 examination, installation of insulation, and disassembly of scaffolding at bolted connections under these operating conditions is a personnel safety hazard. The VT-2 examination is a critical path activity and normally has a duration of 93x to eight hours.

Since the majortty of Class 1 piping is inside the containment building bio shield wall, insulation installation and disassembly of scaffolding will have considerable impact on

the outage critical path and retum to service of the unit.

"The following Byron Station botting examination commitments and material control programs in conjunction with the Proposed Altemate Provisions proved an acceptable level of safety and quality for bolted connections in systems borated for the purpose of controlling reactivity.

l A. In response to NRC Generic Letter 88-05, Byron Station has established a program for i Engineering to inspect all boric acid leaks discovered in the containment building and to evaluate the impact of those leaks on carbon steel or low alloy steel components. All evidence of leaks, including boric acid crystals or residue, is inspected and evaluated regardless of whether the leak was discovered at power or during an outage. Issues -

such as the followmg are considered in the inspection and evaluation: 1) evioonce of corrosion or feetal degradation,2) effect the leak may have on the pressure boundary,

'. -Evaluated in NRC Safety Evaluation Report dated July 22,1996.

, ,.,,..n- , , . . . . - . . - - -

3) possibility of bodc acid traveling along the inside of insulation on piping, and 4) possibility of dripping or spraying on other components. Based on this evaluation, Engineering initiates appropriate correc0/e actions to prevent recurrence of the leak and to repair, if necessary, any degraded materials or onmponents.

B. In addition to the nondestructive examinations required by ASME Section XI, Byron Station has committed to the botting examination requirements of NRC Bulletin 82-02.

In accordance with this Bulletin, at least two nondestructive examination techniques (e.g., ultrasonic, liquid penetrant, magnetic penetrant, or visual VT-1) are performed on bolted connections of the following components: Steam Generators primary manways, i

Pressurizer primary manway, Pressurtzer safety valves, and a total of 22 Reactor

Coolant System isolation valves that are 6" NPS of greater. As a minimum, two nondestructive examination techniques ars used whenever the bolted connection of one of the subject components is disassembled for maintenance or other inspection.

These additional examinations ensure that degradation mechanisms such as stress corrosion cracking or corrosion do not Do undetected in bolted connections critical to reactor safety.'

E/aluation: The Code requires the removal of allinsulation from pressure-retaining bolted connections in systems borated for the purpose of controlling reactivity when performing VT-2 visual examinations during system pressure tests. As an attemative, the licensee has

~

i proposed to perform the VT 2 visual examination with the insulation in place after a minimum 4-hour hold time. In addition, the insulation will be removed for direct visual examination each refueling outage for Class 1, and each period for Class 2 and 3 components.

l The licensee's proposed attemative is essentialy equivalent to Code Case N 533, Mematin Requirements for VT-2 VisualExamination of Class f Insulated Pressure-Retalning Bolted Connections,Section XI, Division f, except the proposed attemative was extended to address Code Class 2 and 3 bolted connections. Code Case N-533 is currently under review by the NRC staff and has not yet been approved for use by incorporation into Reguleto;y Guide 1.147, Inservice inspection Code Case Acceptability.

For Class 1 systems, the licensee's proposed attemative provides a thorough approach to ensuring the leak-tight integrity of systems borated for the purpose of controlling reactivity.

l First, the 4-hour hold time allows any leakage to penetrate the insulation, thus provides a means of detecting any significant leakage with the insulation in place. Second, by removing the insulation each refueling outage, the licensee will be able to detect minor l' leakage indicated by the presence of boric acid crystals or residue. This two-phase I approach will provide an acceptable level of quality and safety for bolted connections in -

8 m

borated systems. Therefois, it is recommended that the licensee's proposed aHomative be authorized pursuant to 10 CFR 50.55a(a)(3)(i) for use on Cints 1 systems.

For Class 2 and 3 systems, the frequencies proposed for insulation removal have not been found acceptable by the NRC staff. Therefore, the licensee's proposed acmative should not be authorized for Class 2 and 3 systems.

H. Reauest for Relief No.12R-13. IWF 5300. Inservice Examination and Test Reauirements for Snubbers Request for Relief 12R 13 is part of the Inservice Test (IST) Program and is, therefore, not included in this evaluation. This request for relief will be evaluated by the Mechanical Engineering Branch of the NRC.

l. Reauest for Relief No.12R 15. Use of Code Case N-416-1. Altemate Testino for Class 1.

Class 2. and Class 3 Welded Repaired /Rectaced Components Code Reauirement: Section XI, Table IWA-4700(a) requires that a system hydrostatic test be performed in accordance with IWA-5000 after repairs by welding on the pressure-retaining boundary.

Licensee's Proposed Altemative: Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposes to employ the rules in Code Case N-416-1 with the additional NDE requirements stated below as an attemative to Section XI requirements (as stated):

• After welded repairs or installation of replacement items by welding the following attemative requirements will be met in lieu of performing the hydrostatic pressure test required per paragraph IWA-4000:

(a) Non-destructive examination (NDE) will be performed on the repaired / replaced welds or welded areas in accordance with the methods and acceptance criteria of the applicable Subsection of the 1992 Edition of Section Ill.

(b) 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 Section XI, prior to or immediately upon retum of the component to service.

4-(c) Une of th!s Relief Request shall be documented on an NIS-2 Form.

(d) When NDE is to be conducted per Subsection ND 5222 on a Code Class 3 component, 4 an additional surface examination shall be performed on the tr'ot (pass) layer, (e) When Code Class 3 repair or replacement activities involve socket / fillet welds, a surface examination shall be performed on the subject socket / fillet welds."

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

" Pursuant to 10 CFR 50.55a(a)(3)(i), relief is requested en the basis that the proposed altematives provide an acceptable level of quality and safety.

• Due to the extensive preparation often required to safely accomplish the required system hydrostatic tests (at pressures above normal operating levels) after welded repairs and replacements on Code Class 1,2, and 3 components, these tests present unusual difficulties and often hardship situations for Byron Station. The performance of the altomative provisions in Code Case N-4161 will provide an acceptable level of quality and safety.

"Some of the specific problems typically encountered when preparing and performing these tests include:

" Complicated or abnormal valve line-ups in order to properly vent, fill, and isolate the component requiring testing.

" Relief valves with setpoints lower than the hydrostatic test pressure must be gagged or removed and blind flanged. This process requires the draining and refilling of the system both prior to the test and prior to system restoration.

" Valves that are not normally used for isolation (e.g., normally open pump discharge valves) are often required to provide pressure isolation for an elevated pressure hydrostatic test.

These valves frequently require time consuming seat maintenance in order to obtain a leak tight pressure boundary.

"The radiation exposure to plant personnel involved in hydrostatic test is high in comparison to operational pressure testing due to the large amount of time required to prepare the volume for testing (i.e., installing relief valve gages, performing appropriate valve line-ups, completing valve maintenance, filling and venting, etc.)

"The difficuttles encountered in performing a hydrostatic test are prohibitive when weighed against the benefits. Industry experience, which is supported by Byron Station's experience, shows that most through wallleakage is detected during system operation as opposed to during elevated pressure tests such as ten-year or post-maintenance system hydrostatic tests.

"Little benefit is gained from the added challenge to components provided by an elevated pressure hydrostatic test as compared to that of a system operation test. The stresses experienced during a hydrostatic test do not include the significant stresses associated with the thermal growth and dynamic loading seen during a system operating test. Tnus the

4 system is more likely to experience any through wall leakage at operating conditions due to the combinaCon of dynamic /thermalloading and the normal operating pressure parameters than during the passive conditions associated with a hydrostatic test.

"The acceptability of performing nominal operating pressure tests in lieu of hydrostatic tests is also supponed by the recent approval by the Board of Nuclear Codes and Standards of ASME Code Case N-4161, 'Altemate Pressure Test Requirement for Wolded Repairs or Installation of Replacement items By Welding For Class 1, 2, and 3 Systems,Section XI, Division 1'. This Code Case allows a system leakage test at nominal operating pressure and temperature, in accordance with IWA 5000 of the 1992 Edition of Section XI, to be performed in lieu of a hydrostatic test, provided that Non Destructive Examination (NDE) of the welds (s) is performed in accordance with the methods and acceptance criteria of the applicable subsection of the 1992 Edition of Section Ill. This approach is also supported by Code Case N-498, 'Altemative Rules for 10 Year Hydrostatic Pressure Testing for Class 1 and 2 Systems, Section Xi'. This relief request is a logical extension of that Code Case.

Code Case N-498 is approved for use in Regulatory Guide 1.147, Revision 11. In addition, the ASME Board of Nuclear Codes and Standards has approved Code Case N-416-1,

'Altemative Pressure Test Requirements for Welded Repairs or Installation of Replacement items by Welding, Class 1,2, and 3 Systems,Section XI, Division 1', which incorporates the logic and Attomative Examinations contained within this relief request.

" Based on the above, Byron Station requests relief from the ASME Section XI requirements for performing elevated pressure hydrostatic tests on Class 1, Class 2, and dass 3 repaired / replaced components."

Evaluation: Section XI of the Code requires a system hydrostatic test to be performed in accordance with IWA-5000 after repairs by welding on the pressure-retaininD boundary. The licensee proposes to implement the altamative to hydrostatic pressure tests contained in Code Case N-416-1 for Code Class 1,2, and 3 repairs / replacements. In addition, the licensee will supplement the pressure test with an additional surface examination on the root l

pass layer of Class 3 repair / replacement welds or welded areas.

Code Case N-416-1 specifias that nondestructive examination (NDE) of the welds be performed in accordance with the applicable subsection of the 1992 Edition of Section Ill.

This Code Case also allows a VT-2 visual examination to 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 Section XI. Comparison of the system pressure test requirements of the 1992 Edition of Section XI to those of the 1989 Edition of Section XI, the latest Code edition referenced in 10 CFR 50.55a, shows that:

• The test frequencies and pressure cond tions are unchanged; l

• The hold times either remained the same or increased;

4

• The terminology associated with the system pressure test requirements for all three Code classes has been clarifwHi and streamlined; and

• The NDE requirements for wolded repairs re nain the same Hydrostatic testing only subjects the piping components to a small increase in pressure over i the design pressure and, therefore, does nat present a significant challenge to pressure

boundary integrity.' Accordingly, hydrostatic pressure testing is primarily regarded as a means to enhance leak detection during the examination of components under pressure rather than as a measure of the structuralintegrity of the components, Followng welding, the Code requires volumetric examination (depending on wall thickness) of repairs or replacements in Code Class 1 and 2 piping components, but only requires a surface examination of the final weld pass in Code Class 3 piping. There are no ongoing ,

HDE requirements for Code Class 3 components except for VT 2 visual examination for weks in conjunction with the 10 year hydrostatic tests and the periodic pressure tests.

However, the INEEL staff believes that the examinations required by Code Case N-4161 are commensurate for Class 3 systems when 1) a surface examination is performed on tha root pass layer of butt and socket welds, and 2) a system pressure test at nominal operating pressure is performed, Considering the previous acceptance of Code Case N-416 bj the NRC and the supplemental surface examination on the root pass for Class 3 systems, it is concluded that the licensee's proposed attemative will provide an acceptable level of quality and safety, Therefore, it is recommended that the licensee's pro, nosed altamative, to use Code Case N-416-1 with a supplemental surface examination on the root pass layer of butt and socket welds, be 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, if the licensee intends to continue to implement this Code Case, the licensee should follow all provisions in Code Case N 416-1 with limitations issued in Regulatory Guide 1.147, if any.

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4 J. Reauesi for Relief No 12R 18. Use of CoJe Case h-498-1. Memat/ve Rules fbr 10-Year l Svatem Hvdrostatic Teshna fbr Class 1. 2. and 3 Svstems for Class 3 Svstems Code Reauirement: Sedion XI, Table IWD-26001, Examination Categories D.A, D 8, and D C require hydrostatic testing of Class 3 pressure-retaining components in accordance with IWA 5000 and LWD 5223.

Uganagg'afst9391611emative: Pursuant to 10 CFR 50.55a(s)(3)(i), the licensee has -

proposed to employ the rules in Code Case N-4G8-1 as an attemative to the 10-year hydrostatic pressure test required by Table IWD 25001, Categories D.A D 8, and D.C as follows as stated):

l

• (1) A sys. tem pressure test sha!! be conducted at or near the end of each inspection interval or during the same inspection period of each inspection interval of Inspection Program B.

(2) The boundary subject to test pressurization during the system pressure test shall extend up to and including the first normally closed valve or valve capable of automatic closure as required to perform the safety system function.

(3) The system shall be pressurized to nominal operating 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 noninsulated systems. The system shall be

. maintained at normal operating pressure during the performance of the VT-2 examination.

(4) The VT-2 visual examination shall include all components within the boundary identified in (2) above.

(5) Test instrumentation specified for hydrostatic pressure test is not required."

[

ll Licensee's Basis for Proposed Altemative (as stated):

" Pursuant to 10 CFR 50.55a(s)(3)(i), relief is requested on the basis that the proposed altematives provide an acceptable level of quality and safety."

4 "Recent ASME Code Committee activities have included the approval of Code Case N-498-1, 'Altemative Rules for 10 Year Hydrostatic Pressure Testing for Class 1,2, and 3 Systems', which allows a system pressure test at operating pressure to be performed in lieu

. of the Section XI required hydrostatic test, which is performed at higher pressures. Code e Case N-498-1 is a revision to Case N-498 and incorporates Code Class 3 components.

~

Code Case N-498 has been approved for use in ISI Programs in Regulatory Guide 1.147, Revision 9.

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l 1-

"The technical basis for N 4961 is provided by a paper titled Dowlopment ofin Service

- InspeeCon Sabty PMbsophy kr USA Nucdear Pitnts, ASME,1971 which concludes that an elevated pressure test, as required by ASME Section XI, is not a test of the structural j

integrity of a system, but rather er, enhanced method of leak detection during examination of. ,

componords under pressure.

"Because the Section XI hydrostatic pressures are not significantly higher than the system

- operational pressures, and leakage signaling potential componord defects was readily i noticed at the operating system pressures, the altemative rules of Case fH961 will provide reasonable assurance that the safety and integrity of Class 3 corr.penents will be maintained. -

'Accordingly, Byron Station proposes the following attemative rW ., based on Code Case N-4961, be employed."

Evaluation: The Code requires a system hydrostatic test once per interval in accordance with the requirements of IWA 5000 for Class 3 pressure retaining systems. In lieu of the Code-required hydrostatic testing,. the licensee has requested authorization to use Code Case N-498-1, Attemati,e Rules kr 10 Year System Hydrostatic Testing kr Class 1, 2, and 3 Systems, dated May 11,1994.

The system hydrostatic test, as stipulated in Section XI, is not a test of the structural integrity

(

i of the system but rather an enhanced leakage test." Hydrostatic testing only subjects the piping components to a small increase in pressure over the design pressure; therefore, piping dead weight, thermal expansion, and seismic loads present far greater challenges to i the structural integrity of a system. Consequently, the Section XI hydrostatic pressure test is I primarily regarded as a means to enhance leak detecuon during the examination of vomponents under pressure, rather than as a method to determine the structural integrity of the components. In addition, the industry experience indicatss that leaks are not being i'- discovered as a result of. hydrostatic test pressures causing a preexisting flaw to propagate

through the wall. - In most cases leaks are being found when the system is at normal operating pressure.

t a Code Case N-498, Altemative Rules kr 10 YearSystem Hydrostatic Testing kr Class 1 ad I 2 Systems, was previously approved for general use on Class 1 and 2 syst&4v in Regulatory Guide 1,147, R6v. 9. For Class 3 systems. Revision N-498-1 specifies i

-8. H. Bush and R. A Meccary, " Development ofin-Service Inspection Safety Philosophy for U.S.A. NuclearPowerPlants," ASME,1971

I l .

1 t requirements identical to those for Class 2 components (for Class 1 and 2 systems, the altomative requirements in N-4981 are unchan9ed from N 498), in lieu of 10 year hydrostatic pressure testing at or near the end of the 10 year interval, Code Case N-4981  ;

requires a VT 2 visual examination at nominal operating pressure and temperature in conjunction with a system leakage test performed in accordance with paragraph IWA 5000 of the 1992 Edition of Section XI.

Class 3 systems do not normally receive the amount and/or type of nondestructive examinations that Class 1 and 2 systems receive. While Class 1 and 2 system failures are relatively uncommon, Class 3 leaks occur more frequently and are caused by different failure mechanisms. Based on a review of Class 3 system failures requiring repair during the last ,

i 5 yes 3 " the most common causes of failure are erosion corrosior, JC), microbiologically.  !

Induced conoslon (MIC), and general corrosion, in general, licensees have implemented programs for the prevention 4etection, and evaluation of EC and MIC; therefore, Class 3 l Wystems receive inspection commensurate with their functions and expected failure ,

J mechanisms.

Considering that Code Case N 498 was found to be an acceptable altomative for Class 1 and 2 systems, and that Class 3 systems receive inspections commensurate with their function and expected failure mechanisms, the licensee's proposed altomative, to use Code Case N-4981, should provide an acceptable level of quality and safety. Therefore it is recomwed that the licensee's proposed attemative be authorized pursuant to 10 CFR 00.55a(s)(3)(i). The use of the Code Case should be authorized for the current interval or until such time as the Code Case is publish 6d in a future revision of Regulatory Guide 1.147. At that time, if the licenseo intends to cor,tinue to implement thlm Code Case, the licensee should follow all provisions in Code Case N 4981 with limitations issued in Regulatory Outdo 1.147, if any.

- Documented in Licensee Event Reports and the Nuclear Plant Reliabliity Data System databases.

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1 i i j K. Requent for Rahaf No.12R 17 (Revision 2L Use of Code Case N 50g. Memale Rules & the j SaincGon and Examinanen of Qass 1. 2. and 3 IntecraMy Welded ANachmerda. SecGon XI. .

DMalan 1  :

i

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Code Reauirement: The Code requires examination of integrci ;;df+d attachments as l

specified for Examination Categories B H, B-K, C C, D-A, D 8, and D C. The Code stipulates volumetric or surface examinations, as appropriate, and the extent of examinations. -

l 1

Lloensee's Proposed Memative: Pursuant to 10 CFR 50.55a(s)(3)(i), the licensee has ,

proposed to use Code Case N 50g, Memale Mu6es M the Selection ord Examination of Class 1, 2, and 3 IntegraMy Weided Attachments,Section XI, Ovialon f, in lieu of the requirements of the Code for Class 1,2, and 3 integralh-welded attachments. The licensee ,

stated:

'The requirements of Code Case N 50g will be used to select and examine ;,',tegrelly welded attachments. W selection of the integral attachments reflects 10% of the total of all

none

4mpt (per IWX1220) ASME Class 1,2, and 3 piping, pump, and valve integral attachments, and in the case of multiple vessels of similar design, function, and service, an '

integral 9 welded attachment of onY one of the multiple vessels."

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

" Pursuant to 10 CFR 50.55a(a)(3)(i), relief is requested on the basis that the proposed attematives provide an acceptable level of quality and safety. Relief is being requested to allow the use of altomate requirements for th. examination and selection of Class 1,2, and 3 integral attachments detailed in Code Case N 50g. The basis for this request is as follows:

1) During the first inservice inspection interval at the Byron Generating Station, no inservice flaws were detected in intepmily welded ettschments which would affect safety or compromise the integrity of se plant.

2) Within the commercial nuclear power industry, failures of integral attachments have been very rare and have not affected plant safety. When failures or inservice defects are found in integral attachments, they are usually associated with a support which has been damaged during operation. . Therefore, flawed or broken integral attechments are typicalh detected during the investigation of damaged supports rather than during scheduled inservice inspections. One feature of Code Case N 50g is to focus the examination of integral attachments on instances where the deformation of the associated supports is identified. The requirement will increase the likelihood of locating damaged integral attachments and thereby increase the level of quality and ,

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safety provided by these altomative rules, as compared to the rules of the 1989 Edition of Section XI.

3) There is a significant amount of man rom exposure and cost associated with the scheduled inspection of Class 1,2 and 3 inta tral attachroents.

4) Unlike ASME Section XI 1989 Edition, the attomate selection criteria of Code Case N 509 does not impose a minimum thickness requirement for the inspection of an integral attachment. Therefore, a greater population of integral attachments will be available for inspection because selection will not be limited to those above an arbitrary thickness. This provision improves the quality and safety level established by these examinations.

5) The altomate rules of Code Case N 509 provide an acceptable level of quality and safety."

Evaluatien: The licensee has proposed to apply the requirements of Code Case N 509 as an attemative to the Code requirements for the examination of integrally-welded attachments on Class 1,2, and 3 piping and components. The licensee has also committed to supplement the Code Case with a minimum examination sample of 10% of integral a+tachments to non-exempt Class 1,2, and 3 components. Considering that most of the Code examination requirements are based on sampling to ensure the detection of service-induced degradation,6xtending the sampling philosophy to the integral attachment welds will provide an equivalent level of quality and safety. Therefore, it is recommended that the altemative, to use Code Case N 509 with the minimum sample size of 10%, be authorized pursuant to 10 CFR 50.55a(s)(3)(l). The use of this altomative should be authorized for the current interval at Byron Units 1 and 2, or until Code Case N 509 is approved for general use by reference in Regulatory Guide 1 147. After that time, the licensee must follow the conditions, if any, specified in the regulatory guide.

K. Reauest for Relief No.12R 18. Use of Code Case N-52). Attemat/ve Rules for Deferral of InsDections of Nottle-to-Vessel Welds. Inside Radius Sections. and Nozzle-to Safe End Wolds of a Pressurized Water Reactor (PWR: Vessel QS4e Reauirement: Section XI, Table IWB 25001, Examination Category B-D, items B3.90 and 83.100 require that, for reamr prest.ure vessel (RPV) nozzle welds and inner radius sections, at least 25% but not more than 50% (credited) of the nozzles shall be examined by the end of the first inspection period and the remainder by the end of the inspection interval.

l

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Examination Category B F, item B5.10, Note (1) states that the reactor vessel nonle to safe end weld examinations may be performed with the vessel nonle examinations.

Licensee's Proposed Attemative: Pursuant to 10 CFR 50.55e(s)(3)(i), the licensee has proposed to use Code Case N 521 as an attemative to the Code requirement to examine at least 25% of the vessel-to nonle welds and nonle inner radius sections during the first examination period. All of the RPV nonle to-vessel welds, the nonle inside radius sections, and the nozzle-to safe end walds will be examined concurrently with the reactor vessel ten year examinations at or near the end of the second 10 year inspection interval.

Scheduling will be such that no more than 10 years will occur between these examinations, except when the length of a 10-year intervalis adjusted in accordance with IWA 2430. The welds and examination areas are listed below.

Nonie to Vessel (item inside Radius Sections Nonle to-Safe End Wolds 83.90) (item B3.100) (Item B5.10)

Unit 1 Unit 2 Unit 1 Unit 2 Unit 1 Unit 2 RPVN A RPVN A RPVN A NIR RPVN-A NIR F 1/RPVS-A* F1/RPVS.A RPVN B RPVN B RPVN B NIR RPVN B-NIR F1/RPVS B F1/RPVS-B RPVN-C RPVN-C RPVN C NIR RPVN-C NIR F1/RPVS-C F1/RPVS-C RPVN D RPVN-D RPVN-D-NIR RPVN D NIR F1/RPVS-D* F1/RPVS D RPVN-E RPVN E RPVN-E NIR RPVN E NIR F1/RPVS E* F1/RPVS E RPVN F RPVN F RPVN F NIR RPVN-F NIR F1/RPVS F F1/RPVS-F RPVN-G RPVN-G RPVN G.NIR RPVN-G-NIR F1/RPVS G F1/RPVS-G RPVN H PPVN H RPVN H-NIR RPVN H-NIR F1/RPVS H* F1/RPVS H

• Surface examinations performed in Period 1 of Interval 1. Interval 2 surface examinations will be performed in Period 1 of Interval 2.

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

• Pursuant to 10 CFR 50.55a(a)(3)(l) and (ii), relief is rerquested on the basis that the proposed attematives provide an acceptable level of quality and safety and on the basis that compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

• Relief is requested to defer 100 percent of the reactor vessel nonle to-vessel weld examinations, the nonle inside radius section examinations, and the nonle to safe end weld examination to the end of Byron Station's second ten year inspection interval.

• Byron Station believes that performing 25 percent to 50 percent of the reactor vessel nonic examinations in the first period of the second inspection interval would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety for the following reasons:

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i

1) The vendor cost alone (not including site training, plant support, or potential or!tical path time) to perform these examinations with automated tooling in the first inspection per6od  ;

is currenty estimated in excess of $500,000. The cost to perform these same examinat6ons at the end of the second inspection interval concurrent with the reactor vessel ten year examination is estimated at only $60,000. The major expense .

l associated with the Arst inspection period examinations is the added equipment and i

( personnel mobilisation oosts and equipment assembly and disassembly costs. i

2) Approximately one to two man rom of exposure is currently expended for automated equipment assembh and disassembly in the reactor cavity area. Under current Code rules, this personnel exposure would be incurred twice, once for the first period noule >

examinations and again fcMhe reactor vesse! examination at the end of the inspection interval. Performing the noule examinations concurrent with the reactor vessel ten-year examinations will save approximately one to two man-rom of exposure. ,

• in addition, Comed / Byron Station believes that deferral of 100 percent of the reactor vessel noule examinations to the end of the second inspection interval will provide an acceptable level of safety and quality for the following reasons:

l

• All of Byron Station's Reactor Vessel hot leg noule to vessel welds, and hot leg noule to safe end welds were examined durbg 'ho first period of the first ten year inspection interval. No indications or relevant conditions were discovered that required successive inspections in accordance with Paragraph lWB 2420(b). Furthermore, no inservice repairs or replacements by welding have ever been performed on any of the .

noule to vessel wolds, noule inside radius sections, or noule to safe end welds at  !

Byron Station.

• All of the Unit 1 components (except as noted) listed in Table 1 were examined per i applicable Category B D or B F requirements during the third period of the first interval.

4 All of the Unit 2 components listed in Table 1 will be examined per the applicable l Category B D or B F requirements during the third period of the first interval. The i performance of these examinations in the first interval such that no more than ten years will transpire until the second interval examinations provides a reasonable assurar,ce of operational readiness.

• From an industry perspective, the deferral of Byron Station's noule examinations to the end of the second inspection interval will not decrease the level of qua.lity 6nd safety because PWR vessels similar to Byron Station's have been operating for over 20 years I with no recorded inservice induced flaws or potential degradation mechanisms. Since l each PWR vesselin operation !s representative of the operating conditions throughout the industry, continued inspaJJon of these vessels ensures that any potential degradation mechanism will be detected.

4

• The pressurizer and primary steam generator noule to vessel welds, inside radius sections, and noule to safe end welds are similar in configuration, material properties, weld process parameters, and operate in the same reactor coolant system environment ,

as the reactor vessel noules. Due to this similarity, distribution of the pressurizer and l steam generator noule examinations in accordance with Examination Category B-D

, and Examination Category B F will further substantiate the integrity of the reactor vessel l I

l

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- - . . ~ . _ - - _ _ - - -

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nouies unbi mey no examined m w new me end of the second ins =vice inspection ,

interval.

' Performing all the automated reactor vessel examinations during a single refuelir.3 outage improves consistency of the examinations by uhlizing the same equipment, personriel, and .

procedures. Moreover, this improves the reliability and reproducitdlity of the examinadons.'

Evaluation: The Code requires the examir:stion of at least 25%, but not more than 60% of l RPV nozzles and associated inside radius (IR) sections and rioule safe ends during the Arst  !

Inspection intenal. The licensee has requested authorization to use Code Case N 521 and j defer examination of these erzas until the end of the second 10 year interval.  ;

i Code Case N 621 states that examination of RPV noulos, IR sections, and noulo-to safe  !

end wolds may be deferred provided (a) no inservice repairs or replacements by welding ['

have ever been performed on any of the subject areas, (b) none of the subject areas contain identiAed flaws or relevant conditions that currently require successive inspections in accordance with IWB 2420(b), and N N TH is not in the first interval. {

i The licensee has confirmed that the above nonditions have been met, in addition, the  !

licensee has volumetrically examined all the sebjcot areas during the third period of the Arst 10-year interval. By examining the noule-to vessel welds, and associated IR sections and noule to safe end wolds, at the end of the Arst 10-year intervel, the licensee has established a new sequence of examinations that will not exceed 10 years between 3 4 inspections. Because the licensee repeated the examinations at the end of the previous interval and will me,et the conditions in the Code Case, the licensee's proposed aNemative -

will provide an acceritable level of quality and safety since the maximum time of 10 years between inspections will not be exceeded. Therefore, it is recommended that the licerisee's proposed ahomative be authorized pursuant to 10 CFR 50.55a(a)(3)(i).

3.0 CONCLUSloN i The INEEL staff has revised the licensee's submittels and concludes that for Requests for Relief L2R-06,-06,-07,-06,10,-15,-16,17, and 18, the licensee's proposed altomatives to

' the Code requirements provide an acceptable level of ouality and safety. Therefore, it is f recommended that these proposed altematives be autnorized pursuant to 10 CFR 50.65a(a)(3)(i). For Request for Relief 12R 11, Revision 1, the proposed altemat!ve 28-4 1

• *, o provides an acceptable level of quality and safety for Class 1 systems. Therefore, it is recommended that the proposed aNomative be authorized pursuant to 10 CFR 50.55a(s)(3)(i) fg Class 1 systems oniv. The licensee's proposed aHomative should not be authortred for Class 2 and :s systems.

For Request for Relief 12R Og, N is concluded that the Code requirements are impractical for the subject welds. Therefore, H is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(l).

Request for Relief 12R 13, regarding inservice testing issues, will be evaluated elsewhere by the Mechanical Engineering Branch.

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