ML20207G979

Requests NRC Staff Authorization for Alternative Use of Mechanical Nozzle Seal Assemblies as Described in Attachment a for RCS Applications Until Next Refueling Outage

ML20207G979
Person / Time
Site:	Waterford
Issue date:	03/10/1999
From:	Ewing E ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
W3F1-99-0043, W3F1-99-43, NUDOCS 9903120209
Download: ML20207G979 (16)

Text

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y Entergy Operitions,Inc.

Killona, LA 70066 Tel 504 739 6242 E arly C. Ewing, lti

{L}{ejjsawanewawycaus W3F1-99-0043 A4.05 PR March 10,1999 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555

Subject:

Waterford 3 SES Docket No. 50-382 License No. NPF-38 Use of Mechanical Nozzle Seal Assemblies at Waterford 3 Gentlemen:

Under the provisions of 10 CFR 50.55a(a)(3)(i), Entergy requests NRC Staff authorization for alternative use of Mechanical Nozzle Seal Assemblies (MNSAs) as described in Attachment A for Reactor Coolant System (RCS) applications until the next refueling outage (RF10). Use of the MNSAs for restoring structuralintegrity and leak tightness to the RCS provides an acceptable level of safety and quality. A similar request has been previously approved by the NRC Staff as referenced in

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Attachment A.

Based on industry experience with Pnmary Water Stress Corrosion Cracking (PWSCC) in reactor coolant system (RCS) instrument nozzles, Entergy performed an inspection of Inconel Alloy 600 instrument nozzles susceptible to primary water stress corrosion cracking during Refuel Outage 9. Although Waterford 3 is classified as a low susceptibility plant based on guidelines developed by the Combustion Engineering Owners Group, the visualinspection of the RCS nozzles located on the [pp pressurizer, RCS hot leg, RCS cold leg and steam generator identified five leaking nozzles. These nozzles are at the following locations:

Pressurizer top head instrument tap (RC-310)

Pressurizer top head ' *ument tap (RC-311)

RCS hot leg #1 RTD at u,-ITE-112HC1 RCS hot leg #1 cempling line (RC-104)

RCS hot leg #2 D/P instrument (RC-DPT-9126-SMA) 990312O209 990310 I~~

.PDR ADOCK 050003824 P

PDR u

Use of Mechanical Nozzle Seal Assemblies at Waterford 3

.W3F1.-99-0043 Page 2 March 10,1999

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The leaking pressurizer nozzles are being corrected with partial nozzle replacements in accordance with ASME Section XI.

To perform similar corrective measures on two of the three leaking nozzles on the RCS hot leg, a full core offload would be required. A full core offload is required to I

lower the RCS water level sufficiently to perform the required welding. This process will extend the current refueling outage significantly. Therefore, Entergy requests MRC Staff approval of this alternative for the three RCS hot leg nozzles.

' Additionally, Entergy requests NRC Staff approval of this alternative for use in other l

RCS locations in the event additional leaking nozzles are identified prior to Refuel i

Outage 10.

On March 5,1999, a telephone conversation was held between Entergy and members of the NRC Staff, including Chandu Patel and members of the NRR i

Materials and Mechanical Engineering Branches to discuss the identified leaks and corrective action plans. From that conversation, it was concluded that NRC Staff

. approval of the proposed methods used to demonstrate safety and quality is required. However, because these methods are consistent with the ASME Code and are generally acceptable to the NRC, Entergy believes specific NRC approval of the i

analysis results is not necessary to support restart. The results of the analysis will be'provided to the NRC Staff for their review upon completion. This is expected to occur by March 31,1999. Attachment A provides the bases for the requested 3

alternative, describes the methods to be used for analyzing the MNSA devices, and

- describes the prototype testing used for their qualification.

As startup from the current refueling outage is contingent on approval of this request, Entergy respectfully requests NRC Staff review and approval of our request for use of this alternative by March 21,1999.

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Use of Mechanical Nozzle Seal Assemblies at Waterford 3

,W3F1.-99-0043 Page 3 March 10,1999 Should you have any questions or comments concerning this request, please contact me at (504) 739-6242 or Curt Taylor at (504) 739-6725.

Very truly yours, E.C. Ewing Director Nuclear Safety & Regulatory Affairs ECE/ CWT /ssf

Attachment:

Relief Request cc:

E.W. Merschoff, NRC Region IV C.P. Patel, NRC-NRR J. Smith N.S. Reynolds NRC Resident inspectors Office Administrator Radiation Protection Division (State of Louisiana) l American Nuclear Insurers

W3F1-99-0043 ATTACHMENT A Request for Alternative 1S12-011, Revision 0 l

i ENTERGY OPERATIONS, INC.

WATERFORD 3 2" TEN YEAR INTERVAL REQUEST FOR ALTERNATIVE NO. ISI2-011, Revision 0 i

1. SYSTEM:

Reactor Coolant System (RCS) Piping

2. COMPONENT:

RCS hot leg No.1 RTD Nozzle at RC-ITE-112 hcl RCS hot leg No.1 Sampling Line Nozzle (RC-104)

RCS hot leg No. 2 D/P Instrument Nozzle (RC-DPT-9126-SMA)

3. CODE CLASS:

ASME Section III, Class 1

4. SECTION XI APPLICABILITY:

1992 Edition with portions of the 1993 Addenda as identified in the W3 ISI Program

5. CODE REQUIREMENTS:

IWA-4170 requires repairs and the installation of replacements to be performed in accordance with the Owner's Design Specification and the original Construction Code of the component or system. The af fected system (RCS) piping was designed and constructed to the rules of ASME Section III, Subsection NB,1971 Edition, through and including the Winter 1971 Addenda. Rules for replacing ASME Section III, Class I welded piping nozzle integrity with mechanical clamping devices are not clearly defined by ASME Section Ill.

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REFERENCES:

1. Letter from J. L. Rainsberry (SCE) to Document Control Desk (NRC), dated July 11,1997;

Subject:

Docket Nos. 50-361 and 50-362, Mechanical Nozzle Seal Assembly Code Replacement, Request for Relief from 10 CFR 50.55a, San Onofre Nuclear Generating Station, Units 2 and 3,

2. Letter from Mel B. Fields (NRC) to Dwight E. Nunn (SCE), dated November 20, 1997;

Subject:

Mechanical Nozzle Seal Assembly Code Replacement For San Page1of11

Onofre Nuclear Generating Station, Units 2 and 3, Request for Additional Information (TAC Nos. M99558 and M99559)

3. Letter from J. L. Rainsberry (SCE) to Document Control Desk (NRC), dated December 12,1997;

Subject:

Docket Nos. 50-361 and 50 362 Mechanical Nozzle i

Seal Assembly Code Replacement Request for Relief from 10 CFR 50.55a, San Onofre Nuclear Generating Station, Units 2 and 3,

4. Letter from J. L. Rainsberry (SCE) to Document Control Desk (NRC), dated January 5,1999;

Subject:

Docket Nos. 50-361 and 50-362, Mechanical Nozzle Seal Assembly Code Replacement Request for Relief from 10 CFR 50.55a, San -

Onofre Nuclear Generating Station, Units 2 and 3,

5. Letter from W. H. Bateman (NRC) to H. B. Ray (SCE), dated February 17,1998;

Subject:

Use of Mechanical Nozzle Seal Assembly For The San Onofre Nuclear Generating Station, Units 2 and 3 (TAC Nos. M99558 and M99559)

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7. REQUESTED RELIEF:

Leaks attributed to Primary Water Stress Corrosion Cracking (PWSCC) have been detected in the nozzles listed in Section 2. The typical repair of these nozzles utilizes either an internal or external weld repair, or a half nozzle replacement. As an alternative under the provisions of 10 CFR 50.55a(a)(3)(i) the use of a Mechanical Nozzle Seal Assembly (MNSA) is proposed as a replacement to restore nozzle integrity and prevent leakage of the nozzle assemblies for one (1) cycle of operation.

In the event leakage is detected at other locations during plant restart or before the next scheduled refuel outage similar to the conditions described in this request, it is proposed that the methods described within also be applied to those conditions.

8. BASIS FOR RELIEF:

8.1.

Background

The RCS piping (hot legs) including the nozzle penetration assemblies were designed by Combustion Engineering. The nozzles and RCS piping are described below:

Hot Leg DPT (Pressure Monitoring) and Sampling Nozzle e

The nozzle neck (portion that penetrates the RCS piping) is a Ni-Cr-Fe, SB-166 material (Inconel 600) with a SA-182 Type F316 welded safe end. The nozzle bore is approximately % inch with an outside diameter of 0.993 inches. The total length of the nozzle, including the safe end, is approximately 9 inches. The J-weld uses Inco-182 filler material.

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. - Hot Leg RTD Nozzle The RTD. s tzle is a one piece nozzle (does not contain a safe end) manufactured from Ni-Cr-Fe, SB-166 material. The inside bore is approximately 0.3 /7 inch for about 2 inches from the RCS end of the nozzle, then an inside chamfer of 45' expands the bore to approximately 7/16 inch for the remainder of the nozzle length. The outside diameter is

.993 inches and overall length is approximately 8 3/8 inches. The J-weld j

uses Inco-182 filler material.

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RCS Hot Leg Piping l

The RCS hot leg piping in the area of the affected nozzles is fabricated from SA-516 Grade 70 with a stainless steel SA-240 Type 304L liner.

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The hot leg piping has a nominal diameter of 42.0 inches and a minimum wall thickness of 3.750 inches.

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The Ni-Cr-l'e heat affected zone of the J-weld has proven to be susceptible to I

PWSCC. Numerous instances of nozzle cracking have been identified at l

other facihties in recent years. Studies performed by the Combustion Engineering Owner's Group (Repor! CE-NPSD-690-P) have found that crack

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growth is axial. Eddy current examinations performed cn one of the leaking i

pressurizer nozzles at W3 has confirmed the existence of axial cracks l

condstent with descriptions contained in the report. The dominant conditions l

that promote axial growth rather than circumferential growth is high circumferential stress (hoop stress) compared to the axial stress. The hoop l

stress is a residual stress caused by weld shrinkage that diminishes quickly as the distance from the J-weld increases.

4.

The susceptibi ay to cracking is based on several factors that deal with i

material, stresa, and environment. Using the CE Owners Group criteria, W3 l

is considered a low susceptibility plant.

l Inspections required by ASME Section XI, IWB-2500 for Examination i

Category B-P have been performed t.r ng each refueling outage.

3 Additionally, the inspections recommended by the CE Owner's Group have been performed commensurate with facilities identified as having Icw susceptibility. During the current refueling outage (RF9), Entergy performed more detailed inspections as a result of cracking at another low susceptibility plant in 1997. Evidence ofleakage was discuvered on two pressurizer j

nozzles and tree RCS hot leg nozzles (See Section 2). This is the first j

occurrence of RCS nozzle cracking at W3.

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Leakage of the pressurizer nozzles is being corrected with a partial nozzle replacenent in accordance with ASME Section XI. However, two of the l

RCS hot leg nozzles are located below the midloop water level and the other l

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i is marginally located above the midloop water level. The use of a welded i

repair is not possible for two of the nozzles and is not desirable for the

. remaining nozzle without draindown. Draindown would require a complete core offload, not planned for the current outage and would significantly extend the current outage. Therefore, the use of MNSAs for restoring l

structural integrity and leak tightness to the RCS piping nozzles is proposed i

8.2.

Application and Description 1

The MNSA is a mechanical device tht.t replaces the function of the J-weld to prevent leakage from cracks and to resore structural integrity. It also acts to i

restrain the nozzle from ejection in the unlikely event of complete J-weld failure (360' circumferential crackt l

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The seal is created by compressing the Grafoil split packing against the nozzles at the nozzle to RCS hot leg OD interface. The compression collar j

transmits the load to the Grafoil split packing while the packing is retained i

within the seal retainer and compression collar. The compressive load is generated when hex head bolts are threaded into the RCS piping and torqued.

l The installation of the hex head bolts does not violate the primary pressure l

boundary. The compressive load is then transmitted to the compression

- collar through the upper flange. No additional bending or axial loads are imparted on the nozzle or existing J-weld by application of the MNSA.

i The top plate is anchored to the upper flanges through tie rods and secured in l

place by hex nuts preventing ejection of the nozzle. The top plate is installed with a small gap between the nozzle and its bottom surface to account for i

thermal growth he top plate will act as a restraint only if the nozzle to RCS weld completd' (n and other interferences are overcome will the top plate act as a restran Am <ise it is not subject to ariy loads during normal operation.

8.3.

MNSA DESIGN In acco, dance with ASME Section XI, IWA-4170, replacements shall meet the requirements of the Owner's Design Specifications and the original j

Construction Code. Altetnatively, replacements may meet later editions of i

the origind onstruction Code provided-i 1.

The requirements affecting the design, fabrication, and examination of the item to be used for replacement are reconciled with the Owner's SpecHication through the Stress Analysis Report,' Design Report, or otho suitable method that demonstrates the item k satisfactory for the specified design and operating conditions.

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Mechanical interfaces, fits, and tolerances that provide satisfactory performance are compatible with the system and component i

requirements.

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Materials are compatible with installation and system requirements.

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The Design Specification for the RCS piping identifies the original l

Construction Code as ASME Section III,1971 Edition, through and j

including the Winter 1971 Addenda. Design and manufacture of the MNSA i

is in accordance with ASME Section III, Subsection NB,' 1989 Edition which is approved in 10 CFR 50.55a. The modification of the RCS piping to accommodate the MNSA is analyzed to the requirements specified in the Design Specification and the original Construction Code. As required by ASME Section XI, an amendment to the existing Stress Report will be completed and will include the ASME Section XI reconciliation for use of the 1989 Edition of ASME Section III as it applies to the MNSA and its l

interface with the RCS hot leg piping.

ASME Section III, NB-3600 (Piping Design) rules are followed for the design and manufacture of the MNSA for an RCS pipe instrument nozzle.

Specifically, NB-3670 (Special Piping Requirements) permits Ge use of Sleeve Coupled and Otuer Patented Joints (NB

'" A and gives requirements for mechanicaljoints "... for wlJ.

.aandards exist". NB-3600 specifies the design of the mechanical joint must: a) prevent separation of the jcint under all Service Loadings; b) be accessible for maintenance, removal, and replacement after service; c) a prototype must be subjected to performance tests to determine the safety of thejoint under simulated service conditions, or thejoint design shall be in accordance with the rules of ND-3200.

8.3.1.

Design by Analysis (NB-3200)

In addition to the prototype testing discussed in Section 8.3.2, the MNSA devices are analyzed to meet the requirements of NB-3200.

The MNSA is designed as an ASME Section III, Class 1, safety related primary pressure boundary in accordance with the rules of NB-3200. An amendment to the RCS Piping Stress Report CENC-1444 for W3 will be completed assuring stresses under all service conditions do not exceed the Code allowables as stated within Section III and that fatigue limits are not exceeded using the i

conditions contained in Design Specification 09270-PE-140.

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8.3.2.

Prototype Testing In addition to the integrity and functional characteristics demonstrated by design and analysis in accordance with NB-3200, i

significant prototype testing was performed to demonstrate the functionality, structural integrity, and the sealing capability under all j

service loadings. Detailed descriptions of the prototype testing and i

CE ABB Test Reports TR PENG-033 and TR-PENG-042 have been i

provided to the NRC Staffas enclosures to Reference 3. The NRC l

Staff's evaluation of the prototype testing is contained in Reference i

5.

The objective of the prototype testing was to qualify one MNSA for a nozzle located at the bottom of a cressurizer and om MNSA for a l

RCS hot leg nozzle by performing 1.ydrostatic, thern el cycling, and seismic tests. The prototype testing verified leak tightness and structural integrity under operating conditions.

7 Each nozzle was clamped by a MNSA on'a fixture mounted to an

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autoclave. The nozzles were not welded to the mounting fixtures.

l The hydrostatic test consisted of pressurizing the autoclave to 3,175 psig'at ambient temperature conditions. Several tests were l

performed on the RCS hot leg MNSA prototype for short periods of i

time and one additional tcst was performed for a longer duration of 3 j

hours. No leakage was detected after the test.

.j After completion of the hydrostatic test, each MNSA prototype was subjected to a thermal cycling test consisting of 3 heatup and l

cooldown cycles. Each cycle consisted of heating the autoclave from ambient temperature to 650 F at a rate of 150'F/ hour and raising the pressure to 2500 psig. The autoclave contained a boric acid solution comparable to that found in the RCS. The elevated temperature / pressure condition was held for at least 60 minutes, after i

which the autoclave was cooled down to ambient conditions. No leakage was observed during these tests. At the conclusion of the tests, the MNSAs were disassembled and examined for boric acid deposits on the internal surfaces of the flange and Grafoil gaskets.

None were detected.

i The seismic testing consisted of subjecting a MNSA mounted on a shake table to five operating basis earthquake events and one safe shutdown earthquake event. The mounting fixture permitted pressurization to 3,175 psig at ambient temperature du-in;; the l

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i seismic test. The test results indicate that no mechanical damage occurred and no leakage was present. Information contained in the Enclosure to Reference 3 provided a basis for performing the seismic testing using ambient temperatures and concluded that the test results were applicable to hot conditions.

i The test program and test results described in CE ABB Test Reports i

TR-PENG-033 and TR-PENG-042 have been reviewed and found to adequately represent or bound the conditions for which Entergy proposes to install MNSAs at the W3 facility. The test data along with the analysis provides assurance that the MNSA is capable of performing as a RCS pressure boundary and preventing leakage j

during all modes of operation and all accident conditions.

t The MNSAs to be installed at W3 will be subjected to the conditions described below wish are obtained from the Design Specification and form pan 4 6,,,# 9t malysis. As evidenced by the l

prototype tot wNaika, & Puaype tert conditions equal or exceed the operatingendiline : ewhich she clamps will be exposed dating enyre < gtw3.

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W3 MNSA

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Cog litions Design l

Design Prmure 2590 psia 2500 psi

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DesignTruere INA kg 650' F 650 F j

NominalC>peraumg Prow;c 2250 psia Normal hotleg Temperature 611* F i

8.3.3.

Maintenance, Removal and Replacemenit l

The other requirement of NB-3671.7 is that the mechanical j

connection be accessible for maintenance, removal, aad replacement after service. The MNSA is manufactured without welding and is l

bolted in place. Disassembly is a mechanical evolution that requires the detensioning of the installation bolting. NB-3671.7 requirements for maintenance, removal, and replacement after service are satisfied by the MNSA design.

j 8.4.

MNSA Materials The metallic portions of the MNSA performing a RCS pressure bcundary function are manufactured in accordance with material specifications specified by ASME Scotion III, Subsection NB and Appendix 1. Additionally, the material meets all requirements contained in NB-2000 including examination j

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1 and testing. Materials are supplied to the provisions of ASME Section III, NCA-3800 by suppliers maintaining a valid Quality System Cer**9eate or a Certificate of Authorization with the scope of Material Supply. A tietallic i

pressure boundary material is certified in accordance with ASME Su 'on Ill, i

NCA-3800.

The non-metallic material (Grafoil) is determined to also perform a safety-related function and is provided under the provisions of a Quality Assurance Program meeting 10 CFR. 50 Appendix B which has been approved by Entergy. Material testing and certification is provided with the material to i

verify compliance with the engineered features that are required to ensure i

functionality and compatibility with the pressure boundary materials and i

environment.

t The MNSA seal assembly is fabricated from stainless steel (SA-479, Type 304 bar stock and SA-453. Grade 660 bolting materials) with the exception of the Grafoil seal. The Grafoil seal material, Grade GTJ, used in nuclear applications is composed of 99.5% graphite, with the remaining 0.5% made l

up of ash, halides, and sulfur. The Grafoil seal itselfis chemically resistant to attack from nearly all organic and inorganic fluids, and is very resistant to i

borated water. Similar Grafoil material is used as valve packing in valves installed in the RCS with acceptable results.

The bolting and tie rod material (SA-453 Grade 660) is a precipitation hardened austenitic nickel chromium stainless steel. Grade 660 possesses general corrosion resistance comparable to that of other austenitic stainless steels. The 660 material has been shown to be susceptible to stress corrosion cracking (SCC) when highly stressed and exposed to reactor coolant during operating conditions. The SCC failures of Grade 660 material have been attributed to high stress levels while exposed to high temperature reactor j

coolant. Typically, the torquing preload is the source of stress that p:miits the i

attack of SCC in this material. However, the typical preload stress in each MNSA attachment bolt is 22,500 psi, which is low relative to the minimum j

yield strength of 85,000 psi for the bolting material. The other 660 items are

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the tie rods. The tie rods are not stressed under normal conditions. Their function is to act as a restraint in the unlikely event a nozzle J-weld were to completely fail and a nozzle were to eject. In this circumstance, the impact load creates a stress of approximately 32,000 psi; this is reduced to approximately 6,000 psi after impact when the tie rods are retaining the nozzle i

against operating pressure. Again, these stresses are well below the yield strength of the material and the higher impact stress is only experienced for an extremely short duration. The packing design prevents exposure of the 660 material to reactor coolant on leaking nozzles and installation stresses are sufficiently below yield strength to prevent SCC for the period requested.

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Although significant information has been provided to the NRC Staffin References 3 and 4 regarding the acceptance of the Grafoil and the SA-453 -

. Grade 660 material for the intended application, the NRC Staff has indicated in Reference 5 that additional information is necessary to determine

- acceptability for long term use. However, as concluded by the NRC Staffin

~ Reference 5, there is sufficient evidence to indicate the proposed materials can i

perform in an acceptable manner for at least one cycle'which is the duration proposed by this request.

8.5 RCS Modification The MNSAs are attached to the RCS hot leg with the SA-453 Grade 660 bolts. To accommodate the bolts, a series of holes are drilled into the RCS in a circular pattern around the nozzle. The addition of the holes in the RCS will be rWyzed and documented in an amendment to Stress Report CENC-1444.

I The analyxis is performed to the requirements of ASME Section III,1971-Edition thmugh and including the Winter 1971 Addenda. The analysis will.

address-i Fatigue to demonstrate that the Code prescribed cumulative usage factor e

of 1.0 is not exceeded (NB-3222.4) l t

That there is adequate reinforcement in the wall of the RCS piping for the bolt holes (NH-3643.3) i i

i That the stresses do not exceed the allowables as stated in the Code.

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9. INSTALLATION 1

The MNSA installation process is non-intrusive on the existizig nozzle integrity.

l There are no activities during installation that require manipulation of the nozzle that i

would challenge the nozzle's position in the RCS pipmg l

Torquing of the MNSA bolts into the RCS piping will be performed at temperatures-above RTuor (58'F) to ensure the bolting stress does not create e potential for brittle

' failure.

10. TESTING ANDINSPECTION 10.1. ASME Section XI Preservice Tiw bolting and tie rods of the MNSA are considered ASME Section XI, Examination Cetegory B-G-2, Item No. B7.50 bolting. As required by IWA-4820, a VT-1 prercrvice inspection will be performed in accordance with IWB-2200.

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9 10.2 ASME Section XI Pressure Tests In accordance with ASME Section XI,IWA-4710(b)(5), component connections, piping, and associated valves that are NPS I and smaller are 4

exempt from pressure testing. However, to ensure quality ofinstallation and j

the absence ofieakage, a pressure test with visual inspection will be performed on each of the installed MNSAs with the insulation removed. The i

test will be performed as part of plant re-start and will be conducted at normal operating pressure with the test temperature determined in accordance with the W3 Pressure and Temperature Limits as stated in the W3 Technicel 4

dpecifications.

10.3 ASME Section XI Inservice Inspection

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The VT-1 inservice inspections required by ASME Section XI for Examination Category B-G-2 are required by " period" over the 10 year interval and would not be performed more frequently than during refueling 4

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. cycles. The VT-2 inspection required by ASME Section XI for Examination c

Category E-P is required to be performed prior to plant startup following each refueling outage. This request for alternative is limited to one cycle of operation; the clamps will be removed and other actions taken before the i

ASME Section XI inspections are required.

- 11. CONCLUSIONS In accordance with 10 CFR 50.55a(a)(3), proposed alternatives to the requirements of i:

paragraphs (c), (d), (e), (f), (g), and (h) of 10 CFR 50.55a, or portions thereof, may be used when authorized by the Director of the Office of Nuclear Reactor Regulation.

l' The applicant is required to demonstrate that under the provisions of 10 CFR 1

50.55a(a)(3)(i), that the proposed alternatives would provide an acceptable level of quality and safety.

Entergy, as the applicant, is proposing an alternative under the provisions of 10 CFR 50.55a(a)(3)(i) to install the MNSA devices as a replacement for restoring integrity.

and leak tightness of the RCS nozzles as described within this request. In combination with this request for alternative and information provided to the NRC Staffin References 1,3, and 4, it is concluded that the proposed attemative provides

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an acceptable level ofquality and safety because:

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e'. The request for the alternative is limited to one cycle of operation.

The design of the MNSA is in accordance with ASME Section III,1989 Edition,

.NB-3671.7 and the rules of NB-3200. Additionally, significant prototype testing has been completed as part ofcompliance with NB-3671.7 which demonstrates functionality and leak tightness during conditions of operations that are representative of W3.

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• Modification of the RCS hot leg will be analyzed in accordance with the original Construction Code (ASME Section III,1971 Edition through and including the Winter 1971 Addenda).- Analysis will include fatigue, reinforcement i

requirements for the bolt holes and assurance that stresses do not exceed Code allowables.

I All methods of analysis, materials, and fabrication meet ASME Section III, e

Subsection NB. This is comparable to the original methods of analysis, materials and fabrication used for the RCS piping.

The non-Code portion of the MNSA (Grafoil packing) is being provided under a program meeting 10CFR50 Appendix B.

After installation, the MNSAs will be pressure tested and inspected (un-insulat d) e for leakage to ensure quality ofinstallation and leak tightness.

The methods demonstrating acceptability of the MNSAs for use at W3 are the same as those evaluated and accepted by the NRC Staff as described in Reference 5.

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