CNRO-2004-00016, Request for Alternative ANO2-R&R-002, Rev. 1 - Use of Mechanical Nozzle Seal Assemblies

Request for Alternative ANO2-R&R-002, Rev. 1 - Use of Mechanical Nozzle Seal Assemblies

ML040780625
Person / Time
Site:	Arkansas Nuclear
Issue date:	03/11/2004
From:	Burford F Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CNRO-2004-00016, TAC MB4272, TAC MB4517
Download: ML040780625 (33)

Text

Entergy Operations, Inc.

1340 Echelon Parkway Jnte rgy Jackson, Mississippi 39213-8298 Tel 601-368-5758 F. G. Burford Acting Director Nuclear Safety & Licensing CNRO-2004-00016 March 11, 2004 U. S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, DC 20555-0001

SUBJECT:

Request for Alternative ANO2-R&R-002, Rev. 1 -

Use of Mechanical Nozzle Seal Assemblies Arkansas Nuclear One, Unit 2 Docket No. 50-368 License No. NPF-6

REFERENCES:

1. Letter to Entergy Operations, Inc. from the NRC (TAC No.

MB4517) dated July 3, 2002

2. Letter to Entergy Operations, Inc. from the NRC (TAC No.

MB4272) dated July 3, 2002

3. Letter to Entergy Operations, Inc. from the NRC dated December 5, 2003

4. Letter CNRO-2002-00010 from Entergy Operations, Inc. to the NRC dated March 1, 2002

5. Letter CNRO-2002-00018 from Entergy Operations, Inc. to the NRC dated April 4, 2002

6. Letter CNRO-2002-00029 from Entergy Operations, Inc. to the NRC dated April 26, 2002

Dear Sir or Madam:

Pursuant to 10 CFR 50.55a(a)(3)(i), Entergy Operations, Inc. (Entergy) requests NRC staff authorization to use the new design of the mechanical nozzle seal assembly (MNSA-2) on various pressurizer nozzle locations at Arkansas Nuclear One, Unit 2 (ANO-2) as documented in Request for Alternative ANO2-R&R-002, Rev. I (see enclosure). Specifically, Entergy proposes the following alternatives regarding the use of MNSA-2 clamping devices on pressurizer heater sleeves and nozzles:

CNRO-2004-00016 Page 2 of 3 (1) As an alternative to removing previously installed MNSA-2 clamping devices and performing welded repairs, Entergy requests NRC authorization to use previously installed MNSA-2 clamping devices as "permanent repairs".

(2) Entergy requests authorization to consider any and all future MNSA-2 installations as permanent repairs.

Entergy understands that the NRC staff is pursuing permanent use of the MNSA-2 device via ASME Code Committee actions. However, until such actions are finalized, licensees must pursue use of MNSA-2s via the provisions of 10 CFR 50.55a(a)(3). The staff most recently authorized temporary use of the MNSA-2 design at ANO-2 and at Waterford Steam Electric Station, Unit 3 (Waterford 3) as documented in References 1 and 2, respectively. These authorizations currently limit the use of MNSA-2s to two (2) operating cycles. Therefore, a request is needed to address the six (6) MNSA-2s installed at ANO-2 for that length of time.

In addition, Entergy requests permanent use of MNSA-2s that may be installed in the future.

In Reference 3, the NRC informed Entergy of its position in the event a licensee decides to keep a MNSA in service beyond two operating cycles. The NRC specified information that should be provided to justify such a request. This information has been incorporated into ANO2-R&R-002, Rev. 1. To aid the staff in its review of the request, Entergy has included as Appendix 2 of ANO2-R&R-002, Rev. 1 a cross-reference that identifies the location of the requested information.

In previous requests to use MNSA-2s, Entergy provided supporting technical documents to assist the staff with its review via References 4, 5, and 6. Those documents were:

1. Westinghouse Test Report No. TR-ME-02-2, Rev. 0, Test Report for Hydrostatic Testing of the Entergy Mechanical Nozzle Seal Assembly (MNSA-2) (Reference 4)

2. Westinghouse Test Report No. TR-CI-02-2, Rev. 0, Seismic Qualification Testing of the Entergy (WSES-3, ANO Units I & 2) MNSA-2 Clamps for Pressurizer Heaters and Instrument Nozzles (Reference 4)

3. Westinghouse Test Report No. TR-CI-02-03, Rev. 0, Test Report for Entergy MNSA-2 Clamps Thermal Cycle Test (Reference 4)

4. Westinghouse Design Report DAR-CI-02-2, Addendum to CENC-1224 Analytical Report for Arkansas Nuclear One Unit 2 Pressurizer (Rev. 0 via Reference 5; Rev. 1 via Reference 6)

These documents are also applicable to ANO2-R&R-002, Rev. 1.

As mentioned above, the NRC staff approved the temporary use of the MNSA-2 at ANO-2 and Waterford 3 (References 1 and 2). As part of these approvals, the staff approved the methodology that was used to determine acceptable application of the MNSA-2 in conformance with ASME Code requirements. Entergy will continue to use this same methodology to evaluate installation of MNSA-2s. Prior to installation, the evaluation must indicate that Code-allowable stress values are maintained.

CNRO-2004-00016 Page 3 of 3 Should you have any questions regarding this request, please contact Guy Davant of my staff at (601) 368-5756.

This letter contains new commitments as identified in Enclosure 2.

Very truly yours, FGB/GHD/ghd

Enclosures:

1. Request for Alternative ANO2-R&R-002, Rev. 1

2. Licensee-identified Commitments cc: Mr. W. A. Eaton (ECH)

Mr. J. S. Forbes (ANO)

Dr. Bruce S. Mallett, Regional Administrator U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 NRC Senior Resident Inspector Arkansas Nuclear One P.O. Box310 London, AR 72847 U. S. Nuclear Regulatory Commission Attn: Mr. T. W. Alexion MS 0-7 D1 Washington, DC 20555-0001

ENCLOSURE 1 CNRO-2004-0001 6 REQUEST FOR ALTERNATIVE ANO2-R&R-002, Rev. I

ENTERGY OPERATIONS, INC.

ARKANSAS NUCLEAR ONE, UNIT 2 REQUEST FOR ALTERNATIVE ANO2-R&R-002, Rev. I COMIPONENTS I IDENTIFICATION Components/Numbers: ANO-2 Pressurizer (2T-1) nozzles as listed below:

e Lower Level Instrument Nozzles (2)

• Upper Level Instrument Nozzles (2) o Upper Pressure Instrument Nozzles (2)

• Upper Vent Nozzle (1)

• Side Shell Temperature Nozzle (1) o Heater Sleeves (96)

Code Class: ASME Section 1II,Class 1

References:

1) ASME Section Xl, 1992 Edition with Portions of 1993 Addenda

2) ASME Section 1II,1989 Edition

3) ASME Section III, 1968 Edition through and including Summer 1970 Addenda

4) Westinghouse Test Report No. TR-ME-02-2, Rev. 0, Test Report for Hydrostatic Testing of the Entergy Mechanical Nozzle Seal Assembly (MNSA-2)

5) Westinghouse Test Report No. TR-CI-02-2, Rev. 0, Seismic Qualification Testing of the Entergy (WSES-3, ANO Units 1 & 2) MNSA-2 Clamps for Pressurizer Heaters and Instrument Nozzles

6) Westinghouse Test Report No. TR-CI-02-03, Rev. 00, Test Report for Entergy Mechanical Nozzle Seal Assembly (MNSA-2) Thermal Cycle Test

7) Westinghouse Design Report No. DAR-CI-02-2, Rev. 1, Addendum to CENC-1224 Analytical Report forArkansas Nuclear One Unit 2 Pressurizer

8) Entergy Operations, Inc., Letter CNRO-2002-00010 to the NRC dated March 15, 2002

9) Entergy Operations, Inc., Letter CNRO-2002-00012 to the NRC dated March 15, 2002 1 of 26

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10) Entergy Operations, Inc., Letter CNRO-2002-00018 to the NRC dated April 4, 2002

11) Entergy Operations, Inc., Letter CNRO-2002-00029 to the NRC dated April 26, 2002

12) NRC Letter to Entergy, Operations, Inc. (ANO-2)

(TAC No. MB4517) dated July 3, 2002

13) NRC Letter to Entergy, Operations, Inc. (Waterford 3)

(TAC No. MB4272) dated July 22, 2002

14) NRC Letter to Entergy Operations, Inc. (ANO-2) dated December 5, 2003 Unit: Arkansas Nuclear One, Unit-2 (ANO-2)

Inspection Interval: Second (2nd) 10-year interval

11. CODE REQUIREMENTS The code of record for performing ASME Section XI repair/replacement activities at ANO-2 is the 1992 Edition with portions of the 1993 Addenda (Reference 1) for pressure testing. ASME Section Xl, IWA-4170 requires repairs and 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 affected pressurizer instrument heater sleeves and nozzles were designed and constructed to the rules of ASME Section l1l, Subsection NB, 1968 Edition through and including the Summer 1970 Addenda (Reference 3). Rules for replacing ASME Section 1II,Class I welded nozzles with mechanical clamping devices are not clearly defined by ASME Section 1II.

IlIl. PROPOSED ALTERNATIVE The typical repair of pressurizer nozzles and heater sleeves uses a half-nozzle replacement with external weld repair. However, due to extensive field machining and temper bead welding activities, these repairs may extend reactor coolant system (RCS) drain-down activities and significantly increase worker radiation exposure.

In support of the Spring 2002 refueling outage at ANO-2, Entergy Operations, Inc.

(Entergy) requested and obtained NRC authorization to use the improved design of the mechanical nozzle seal assembly, designated MNSA-2, for two (2) operating cycles at those nozzle locations listed in Section I, Components, above. Entergy made this request to repair leaks detected while performing inspections during refueling outages and attributed to primary water stress corrosion cracking (PWSCC). The Entergy request to use the MNSA-2 at ANO-2 was submitted to the NRC via Reference 9 with supporting information provided via References 10 and 11. The NRC approved the request in References 12 and 13.

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Pursuant to 10 CFR 50.55a(a)(3)(i), Entergy proposes the following alternatives regarding the use of MNSA-2 clamping devices on pressurizer heater sleeves and nozzles:

(1) As an alternative to removing previously installed MNSA-2 clamping devices and performing welded repairs as described above, Entergy requests NRC authorization to use previously installed MNSA-2 clamping devices as "permanent repairs".

(2) Entergy requests authorization to consider all future MNSA-2 installations as permanent repairs.

IV. BASIS FOR PROPOSED ALTERNATIVE A. Background The pressurizer, its nozzle assemblies, and heater assemblies were designed by Combustion Engineering (CE). The nozzles and heater sleeves are described below:

• Pressurizer Lower Level Instrument Nozzles (2)

The pressurizer instrument nozzles are fabricated from Ni-Cr-Fe, SB-166 material (Inconel 600) with SA-1 82, F-316 stainless steel %-inch diameter socket weld safe ends. The nozzles are welded to the inside of the pressurizer. The nozzles were modified by cutting the nozzles off approximately 2 inches from the pressurizer shall and inserting a new SA 82, F316 stainless steel nozzle (0.640-inch OD and 0.375-inch ID) into the original portion of the inconel 600 nozzles. The new nozzles extend approximately 5 inches beyond the inside wall of the pressurizer. The ends of the new nozzles have a 34-inch diameter socket weld end with a 3/16-inch diameter orifice - the same as the original nozzle.

The new nozzles are attached by a fillet weld on the end of the remaining portion of each Inconel 600 nozzle.

• Pressurizer Upper Level Instrument Nozzles and Upper Pressure Instrument Nozzles (4)

The pressurizer instrument nozzles are fabricated from Ni-Cr-Fe, SB-166 material (Inconel 600) with SA-182, F-316 stainless steel 3/4-inch diameter socket weld safe ends. The nozzles are welded to the inside of the pressurizer. The upper level instrument nozzles contain a 3/16-inch diameter orifice that serves as the system class break from the Class 1 system to the downstream Class 2 system. The nozzle inside bore is approximately 0.614 inch, and the outside diameter is approximately 1.062 inches. The total length of the nozzle, including the safe end, is approximately 13 % inches. The J-groove weld uses INCO-182 filler material.

e Pressurizer Upper Vent Nozzle (1)

The pressurizer upper vent nozzle is fabricated from Ni-Cr-Fe, SB- 66 material (Inconel 600) with a SA-1 82, F-316 stainless steel %-inch diameter socket weld safe end. The nozzle is welded to the inside of the pressurizer. The vent nozzle contains a 3/16-inch diameter orifice that serves as the system class break from 3 of 26

the Class 1 system to the downstream Class 2 system. The nozzle inside bore is approximately 0.614 inch, and the outside diameter is approximately 1.062 inches. The total length of the nozzle, including the safe end, is approximately 11 5/8 inches. The J-groove weld uses INCO-182 filler material.

• Pressurizer Side Shell Temperature Element Nozzle (1)

The temperature element nozzle is fabricated from Ni-Cr-Fe, SB- 66 material (Inconel 600) with a SA-182, F-316 stainless steel 1-inch diameter socket weld safe end. The nozzle inside bore is approximately 0.815 inch, the outside diameter is approximately 1:315 inches, and overall length of the nozzle, including safe end, is approximately 14 1/8 inches. The nozzle is welded to the inside of the pressurizer. The J-groove weld uses INCO-1 82 filler material.

• Pressurizer Heater Sleeves (96)

The pressurizer heater sleeves are manufactured from Ni-Cr-Fe, SB- 67 material (Inconel 600). The heater sleeve assemblies are welded to the internal cladding of the vessel lower head and the heater elements are welded to the lower end of the sleeves. The heater elements are internally supported for seismic loading and vibration by two heater support plates. The outside diameter of the sleeve is approximately 1.25 inches and reduces to 1.156 inches for insertion into the pressurizer penetrations. The inside bore is approximately 0.905 inch. The length of the sleeves varies from approximately 14 3/8 inches long to approximately 18 3/4 inches long, depending on the location on the bottom head. Currently there are eighty-two (82) heaters installed and fourteen (14) heater nozzles plugged.

• Pressurizer Vessel The pressurizer is a low alloy steel vessel with the shell and top head internally clad with 304 austenitic stainless steel and the bottom head with a Ni-Cr-Fe cladding.

The Ni-Cr-Fe heat-affected zone of the J-groove weld has proven to be susceptible to PWSCC. Numerous instances of nozzle cracking have been identified in the industry in recent years. Studies performed by the Combustion Engineering (CE)

Owner's Group (Report CE-NPSD-690-P) have found that the cracking growth is predominantly axial. The dominant conditions that promote axial growth rather than circumferential growth are high circumferential stresses (hoop stresses) compared to the axial stress. The hoop stress is a residual stress caused by weld shrinkage that diminishes quickly as the distance from the J-groove weld increases. The susceptibility to cracking is based on several factors that deal with material, stress, and environment.

Inspections required by ASME Section Xl, IWB-2500 for Examination Category B-P are performed during each refueling outage. Additionally, the inspections recommended by the CE Owner's Group have been performed.

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B. MNSA-2 Installations to Date MNSA-2 clamping devices have been installed at several facilities. Six (6) MSNA-2s were installed on leaking pressurizer heater sleeves (C2, El, E2, F4, Gi, and N2) at ANO-2 during the Spring 2002 refueling outage (2R15). Five (5) of the leaking heater sleeves were identified during plant cool-down; the sixth leaking heater sleeve was identified during plant heat-up. The MNSA-2 clamping devices were installed based on NRC authorization provided in References 10 and 11.

In the ANO-2 Fall 2003 refueling outage (2R16), pressurizer heater sleeves and instrument nozzles were inspected during plant cool-down in accordance with the Generic Letter 88-05 boric acid inspection program. During this inspection, leakage was identified from the MNSA-2 clamping device on pressurizer heater sleeve "C2".

None of the other five MNSA-2 clamping devices exhibited any leakage.

An exhaustive evaluation was performed to determine the root cause of leakage from the MNSA-2 on the "C2" heater sleeve. Based on this evaluation, reactor coolant system (RCS) leakage from the MNSA-2 resulted from undetected 'foil" material residue left around the "C2" heater sleeve. This "foil" was an extremely thin layer of pressurizer base material that was not removed by the machining process.

Extending from the base of the counterbore, the "foil" extended as much as 1500 around the outside diameter (OD) of the heater sleeve. This machining deficiency resulted in a bypass flow-path around the Grafoil seal (described in Section IV.C) through the metal to metal interface between the "foil" and the OD of the nozzle.

The effect of the "foil" was that it prevented the Grafoil seal from sealing directly to the nozzle. The "foil' was not identified during MNSA-2 installation activities since it was not visible with the unaided eye. It was identified during the root cause investigation by a boroscopic examination. Therefore, the cause of leakage was due to an installation deficiency rather than a design deficiency. As a corrective action to prevent reoccurrence, ANO is developing a machining procedure for installation of MNSA-2 clamping devices. The new machining procedure will include a step requiring a boroscopic examination to ensure that unmachined "foil" is not present in the counterbore.

C. MNSA-2 Anplication. Description. and DesiQn

1. Overview The MNSA-2 is a mechanical device designed to replace the function of partial penetration J-groove welds that attach Alloy 600 nozzles or heater sleeves to the pressurizer. MNSA-2 provides a seal against leakage and positively captures the nozzle preventing ejection in the unlikely event of complete 360-degree weld failure. Figure 1 shows a representative drawing of the MNSA-2 for heater sleeve installation, and Figure 2 shows a representative drawing of the MNSA-2 for side shell temperature element nozzle installation.

[Drawings for these nozzles plus the lower level nozzle, upper level instrument nozzle, upper pressurizer instrument nozzle, and upper vent nozzle designs are contained in the Addendum to the Design Report (Reference 7).]

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.. '.^ '.

To install the MNSA-2, four holes are drilled and tapped (2-Winch x I W.-inch deep) equally spaced around the leaking nozzle or sleeve. A counterbore (approximately %-inch wide x 3/4-inch deep) is also machined into the surface of the vessel perpendicular to and around the leaking nozzle or sleeve. Four threaded rod studs are threaded into the pressurizer, a split Grafoil primary seal is installed in the bottom of the counterbore, and a split compression collar is placed over the nozzle or sleeve to compress the Grafoil seal. The seal assembly is compressively loaded via the compression collar and the inboard and outboard flange assembly, which is in the annulus region. Hex nuts and Belleville spring washers are used to live load the Grafoil seal to accommodate small changes in load on the seal due to differential expansion or minute relaxation of the seal over time to prevent seal leakage.

To prevent nozzle or heater sleeve ejection in the unlikely event of a complete nozzle or sleeve weld failure, an anti-ejection clamp is also installed and secured in place via the tie rods, Belleville spring washers, and hex nuts. The anti-ejection clamp acts as a restraint only if the nozzle-to-RCS weld completely fails.

More specific details of the MNSA-2 design are provided in Section B.2, below.

2. Comparison of MNSA and MNSA-2 Design The NRC previously authorized use of the original MNSA design at several facilities (e.g., San Onofre, Waterford 3, Calvert Cliffs, and Palo Verde). More recently, the NRC authorized use of the MNSA-2 design at Arkansas Nuclear One, Unit 1 (ANO-1), ANO-2, and Waterford 3 for two operating cycles.

The original MNSA and MNSA-2 use the same materials of construction and the same seal material. They are attached in the same fashion, and the seal is loaded by tensioning bolts or studs.

The MNSA-2 design improves upon the original MNSA design in three ways:

• The counterbore provision that contains the seal

• The manner in which the seal is live-loaded

• The means for diverting leakage, should it occur Each is discussed in detail below.

a) Counterbore Provision MNSA-2 uses nuclear grade Grafoil as the sealing material. In all cases, regardless of the angle of the surface of the pressurizer relative to the nozzle, a counterbore is machined perpendicular to the nozzle to receive and contain the seal. The bottom of the counterbore is perpendicular to the axis of the nozzle, so the angle of the surface of the pressurizer does not affect the leak tightness of the design. When the MNSA-2 seal is compressed, no side loads are introduced, so shoulder bolts used on the original MNSA are not required. The seal designs are simpler than the 6 of 26

original MNSA because they involve no variable angles. Therefore, customizing MNSA-2 components for particular slope angles, for other than bolt lengths, is not required.

b) Seal Live-Loading MNSA-2 uses a live-loaded seal that can accommodate small changes in load on the seal due to differential expansion. The live load provision, provided via Belleville washers, also accommodates minute relaxation of the seal over time to prevent leakage. Finally, it allows for re-tightening of the studs and reloading the seal at some point in the future without disassembly, whereas the original MNSA would require a new seal and complete tear-down and re-assembly to re-energize a seal. Figures 1 and 2 show the use of Belleville spring washers.

c) Leak-Off Diversion Leakage control in the MNSA-2 design is accomplished by using a compression collar which includes a collection area (similar to a lantern ring) positioned immediately outboard of the primary seal, as shown in Figure 1. The compression collar has an additional Grafoil seal at the top that is lightly loaded. The seal blocks leakage from passing up along the outside of the compression collar where it could reach the threaded rods.

The path of least resistance is out through the annulus between the compression collar and the nozzle, tending to divert any leakage away from the fasteners and the vessel. The presence of the collection area does not impair the primary seal in any way.

In the review of the original MNSA design, the NRC evaluated potential corrosion effects of boric acid on the MNSA and associated RCS components. The evaluation concluded:

• Corrosion of the low alloy material with a MNSA installed was determined to be acceptable.

• Boric acid corrosion of the materials of construction for the MNSA was determined to be acceptable based on CE Owner's Group corrosion testing.

• There is no history of galvanic corrosion problems in similar applications with Grafoil contacting low alloy steel.

• Potential for SCC failures of the A-286 bolts was found to be acceptable.

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There are no changes from the original MNSA to MNSA-2 that adversely impact the four conclusions listed above. With regard to the A-286 bolts, the NRC evaluation concluded that the bolts could be exposed to boric acid deposits or slurries, if the MNSA leaks. This evaluation was appropriate because the design did not include provisions for capturing or diverting seal leakage away from bolting materials. Regardless, at the stress levels that exist in the bolts, including a stress concentration factor of four, the bolts would function satisfactorily. In contrast to the original MNSA, the MNSA-2 design includes specific provisions to divert potential seal leakage away from the low alloy steel vessel and the bolting as described below.

The sealing qualities of MNSA-2 are enhanced beyond that of the original MNSA by virtue of the controlled geometry (counterbore), and by maintaining a live load on the seal. The counterbore design has been used routinely in hundreds of similar applications for sealing fixed in-core detectors to flanges on the reactor head in CE units. A variety of other repairs and permanent flange upgrades have been installed on both CE and Westinghouse units using both static and live-loaded Grafoil seal technology. Therefore, the possibility of a leak past the primary seal is very small. Nevertheless, in the unlikely event of such a leak, MNSA-2 is designed to limit exposure of the SA-453 (A-286) bolting material and the carbon steel vessel by providing a leak-off path.

3. MNSA-2 Materials The MNSA-2 assembly is fabricated from the same materials as the original MNSA, though with different application of some of the components. A detailed assessment of the MNSA-2 metallic components as related to general corrosion, stress corrosion cracking of nozzles and fasteners, galvanic effects, crevice corrosion, and surface pitting is contained in Appendix 1 of this request.

There are no corrosion problems associated with the application of the MNSA-2 to Alloy 600 small diameter nozzles.

The stainless steel portions of the MNSA-2 performing an RCS pressure boundary function are manufactured in accordance with material specifications provided in ASME Section 111, Subsection NB and Appendix 1. Additionally, the material meets the requirements contained in NB-2000 including examination and testing. Materials are supplied to the provisions of ASME Section III, NCA-3800 by suppliers maintaining a valid Quality System Certificate or a Certificate of Authorization with the scope of Material Supply. Metallic pressure boundary material is certified in accordance with ASME Section III, NCA-3800.

The primary Grafoil seal material is Grade GTJ (used in nuclear applications) composed of 99.5% graphite, with the remaining 0.5% made up of ash, halides, and sulfur. The Grafoil seal itself is chemically resistant to attack from organic and inorganic fluids, and is very resistant to borated water. Similar Grafoil material is used as valve packing in valves installed in the RCS with acceptable results. The Grafoil material is provided under the provisions of a Quality Assurance Program meeting 10 CFR 50 Appendix B that has been approved by Entergy. Material testing and certification is provided with the material to verify compliance with the engineered features required to ensure functionality and compatibility with the pressure boundary materials and environment.

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In summary, there is no potential corrosion or material stress issues associated with applying the MNSA-2 to the pressurizer heater sleeves or nozzles.

4. MNSA-2 Structural Evaluation The component parts of the MNSA-2 for heater sleeve, side shell, upper pressure instrument, upper level instrument, upper vent, and lower level nozzle installation are being analyzed, designed, and manufactured in accordance with ASME Section 1II,Subsection NB, 1989 Edition (Reference 2), which is approved in 10 CFR 50.55a. The ANO-2 original Construction Code for the pressurizer is ASME Section 1I1,1968 Edition, through and including the Summer 1970 Addenda (Reference 3). As required by ASME Section Xl, an amendment to the ANO-2 Pressurizer Stress Report CENC-1224 (Reference 7) has been completed and includes a reconciliation (see Attachment D of Reference 7) for use of the 1989 Edition of ASME Section III as it applies to the MNSA-2 and its interface with the pressurizer.

The analysis for the MNSA-2 components ensures that:

• Stresses do not exceed the allowables as stated in the Code.

• The Code-prescribed cumulative fatigue usage factor of 1.0 is not exceeded (NB-3222.4) for any component.

The stress analysis considers the loads transmitted to the components of the MNSA-2 due to installation pre-load, normal and upset loads at pressure and temperature, and impact loads due to the ejection of the heater sleeve or nozzle in the unlikely event of a complete failure of the ID J-groove weld. The results of the stress analysis will ensure that the applied stresses on each load-bearing component (tie rods, threaded rods, and top plate) are below the applicable Code allowables, thereby providing assurance of structural integrity for the MNSA-2.

Fatigue evaluations of the MNSA-2 clamp components consider a forty-year design life and ensure fatigue usage factors are less than 1.0 for all components of the MNSA-2.

5. Pressurizer Modification and Structural Evaluation The MNSA-2 is attached to the pressurizer with SA-453 Grade 660 threaded rods and hex nuts. To accommodate the threaded rods, four holes are drilled and tapped into the pressurizer in a circular pattern around the nozzle. To provide a seating surface for the Grafoil seal, a counterbore is machined into the pressurizer extending out approximately % inch from the existing nozzle bore and to a maximum depth of 3 4 inch. The addition of the holes in the pressurizer have been analyzed and documented in an attachment to the addendum to Stress Report CENC-1224 (Reference 7) for the heater sleeve, side shell temperature nozzle, upper level instrument nozzle, upper pressure nozzle, upper vent nozzle, and lower level instrument nozzle locations. The analysis is performed to the requirements of ASME Section 111, 1968 Edition through and including the Summer 1970 Addenda (Reference 3). The analysis provides assurance that:

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• Stresses do not exceed the allowables as stated in the Code.

• The Code-prescribed cumulative fatigue usage factor of 1.0 is not exceeded (NB-3222.4) at any location.

• Adequate reinforcement in the wall of the pressurizer for the tapped holes and counterbore exists (NB-3222.1 and NB-3222.2).

The stress analysis considers all loads evaluated in the original design stress report, including all pressure and temperature transients, the differential thermal expansion loads due to the threaded rods in the tapped holes, compression collar loads, and the loads on the existing J-groove weld at operating and during shutdown conditions. The applied stresses and stress ranges were evaluated at the counterbore region and at the tapped holes for compliance with Code allowables. The applied stresses on the pressurizer were modified by the appropriate geometry factors for non-radial effects (where applicable) and by additional factors to take into account stress interaction between the tapped holes and the counterbore as determined by finite element analysis (FEA). The results of the stress analysis, considering the tapped holes and counterbore in the pressurizer shell, demonstrated that applied stresses are below ASME Code allowables and provide assurance of vessel structural integrity.

Fatigue evaluations of the pressurizer shell in the vicinity of the tapped holes and counterbores consider a forty-year design life and ensure fatigue usage factors are less than 1.0.

The area reinforcement calculations performed in the original design stress report in accordance with ASME Code Section III NB-3332.1 and 3332.2 were updated to evaluate the removal of pressurizer metal area by machining the tapped holes and counterbores. The results of the analysis in Reference 7 ensure that for each pressurizer nozzle or heater sleeve location evaluated for possible MNSA-2 installation, the area available for reinforcement is greater than the area required as a result of metal removal.

6. MNSA-2 Installation The MNSA-2 installation process is non-intrusive on the existing heater sleeve or instrument nozzle pressure boundary, and it does not require draining of the pressurizer to install. In addition to the counterbore, a small groove is machined in the end of instrument nozzles to receive the anti-ejection plate as shown on Figure 2. The tooling is designed to machine the counterbore and groove without disconnecting the pressure boundary heater element, instrument tubing or thermo-well. ANO is also developing a machining procedure for installation of MNSA-2 clamping devices. The new machining procedure will include a step requiring a boroscopic examination of the counterbore. (See Section IV.E for additional information.)

Torquing the MNSA threaded rods into the pressurizer will be performed at temperatures above RTNDT (30'F) to ensure the bolting stress does not create a potential for brittle failure.

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D. MNSA-2 Design Reguirements In accordance with ASME Section Xl, IWA-4170, replacements shall meet the requirements of the Owner's Design Specifications and the original Construction Code. Alternatively, replacements may meet later editions of the original Construction Code provided:

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

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

• Materials are compatible with installation and system requirements.

ASME Section III NB-3200 rules are followed for designing and manufacturing the MNSA-2. Specifically, the joints are designed to meet the following criteria:

(1) Provisions must be made to prevent separation of the joint under all service loading conditions.

(2) The joint must be designed to be accessible for maintenance, removal, and replacement activities.

(3) The joint must either be designed in accordance with the rules of ASME Section IlIl, Subarticle NB-3200, or be evaluated using a prototype of the joint that is subjected to additional performance tests in order to determine the safety of the joint under simulated service conditions.

These topics are discussed below.

1. Joint Integritv In addition to the prototype testing discussed below, the MNSA-2 is analyzed to meet the requirements of NB-3200. The MNSA-2 is designed as an ASME Section III, Class 1, safety-related primary pressure boundary in accordance with the rules of NB-3200 to prevent joint separation under service loads. An amendment to Pressurizer Stress Report CENC-1 224 for ANO-2 (Reference 7) demonstrates that 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 conditions contained in the design specification.

2. Maintenance. Removal, and Replacement Typical for mechanical connections, the MNSA-2 will be accessible for maintenance, removal, and replacement after service. The MNSA-2 is manufactured without welding and is bolted in place, so disassembly is a mechanical evolution that requires de-tensioning the installation bolting.

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3. Prototype Testing The original MNSA design was qualified by a series of tests and analyses. With each specific, new application, a Design Specification and a Design Report were prepared. For MNSA-2 applications on the ANO-2 pressurizer, tests were performed for an outer heater sleeve MNSA-2, the most conservative configuration.

In addition to the integrity and functional characteristics demonstrated by design and analysis in accordance with ASME NB-3200, significant prototype testing was performed to demonstrate the functionality, structural integrity, and the sealing capability using conservative, bounding service loadings. Detailed descriptions of the prototype testing procedures and results (References 4, 5, 6) were provided to the NRC Staff as enclosures to Reference 8.

The objective of the prototype testing was to use the most conservative penetration based on size and geometry to envelop all pressurizer penetration locations at Waterford 3 and ANO-2 for hydrostatic, thermal cycling, and seismic tests. The heater sleeve on the upper hillside of the pressurizer bottom head for Waterford 3 was chosen as this bounding penetration. The prototype testing verified leak tightness and structural integrity of the MNSA-2.

• Hydrostatic Test The heater sleeve fixture was clamped with an MNSA-2 with the heater sleeve filled with demineralized water. The nozzle was not welded to the mounting fixtures. As discussed in Reference 4, the hydrostatic test consisted of pressurizing the seal assembly fixture to 3,250 psig +/- 50 psig at ambient temperature conditions and holding the pressure for 10 minutes.

Several tests were performed on the pressurizer MNSA-2. No leakage or seal damage was detected after the test.

• Thermal Cycling Test After completion of the hydrostatic test, the MNSA-2 prototype was subjected to a thermal cycling test (as described in Reference 6) consisting of three (3) heatup and cooldown cycles. The test fixture was filled with demineralized water. Each cycle consisted of heating the autoclave from ambient temperature (less than 200 0F) to 6501F and raising the pressure to between 2,250 psig and 2,500 psig. The elevated temperature/pressure condition was held for at least 60 minutes, after which the MNSA-2 test fixture was cooled down to ambient conditions (less than 200 0F). The remaining thermal cycling tests started from where the original test fixture cooled. No leakage was observed during these tests. At the conclusion of the tests, the MNSA-2 fixture was disassembled, and visual examinations were performed on both the internal surfaces of the flange and on the Grafoil gaskets to look for evidence of any steam wisps, residual fluid deposits, or liquid stains that would indicate a leak. None were detected.

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• Seismic Testing Seismic qualification was performed in accordance with the guidelines in IEEE-344. A test specimen representative of an outer heater sleeve MNSA-2 design for Waterford 3 was attached to an adapter plate and mounted to a shaker table. The heater sleeve test specimen was not welded to the mounting fixtures. The MNSA-2 components were assembled and installed onto the simulated heater sleeve mock-up. The seismic testing consisted of subjecting the MNSA-2 test rig to five operating basis earthquake events and one safe shutdown earthquake event. The mounting fixture permitted pressurization to 3,175 psig +/- 50 psig at ambient temperature during the seismic test. This elevated pressure was conservatively used to account for the fact that the seismic testing was performed at ambient temperatures rather than operating temperatures. The test results indicate that no mechanical damage occurred and no leakage was present. Information contained in Reference 5 provides a basis for performing the seismic testing using ambient temperatures and concludes that the test results were applicable to hot conditions.

The test program and test results described in References 4, 5, and 6 have been reviewed and found to adequately represent or bound the conditions for which Entergy proposes to install the MNSA-2 at ANO-2. The test data along with the analysis provide assurance that the MNSA-2 is capable of performing as the pressure boundary and preventing leakage during all modes of operation and all accident conditions.

The MNSA-2s installed at ANO-2 are subjected to the conditions stated below which were obtained from the Design Specification and form part of the basis for analysis. As evidenced by the prototype test summaries, the prototype test conditions equal or exceed the operating conditions for which the clamps will be exposed.

Parameters ANO-2 Conditions MNSA-2 Design Design Pressure 2,500 psia 2,500 psia Design Temperature (Pressurizer) 7000 F 7000 F Nominal Operating Pressure 2,250 psia -

Normal Temperature (Pressurizer) 6530 F E. Inservice Inspection

1. ASME Section Xl Preservice The bolting and tie rods of the MNSA-2 are considered ASME Section Xl, Examination Category B-G-2, Item No. B7.50 bolting. As required by IWA-4820, a VT-1 pre-service inspection is performed in accordance with IWB-2200.

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2. ASME Section XI Pressure Tests In accordance with ASME Section Xl, IWA-4710(c), mechanical joints made in the installation of pressure-retaining replacements shall be pressure tested.

During plant startup, the test will be performed in conjunction with aVr-2 inspection at normal operating pressure with the test temperature determined in accordance with the pressure and temperature limits as stated in the ANO-2 Technical Specifications.

3. ASME Section Xl Inservice Inspection Entergy inspects components in the reactor coolant system (RCS) in accordance with NRC Generic Letter 88-05, Boric Acid Inspection Program. As part of this inspection program, Entergy will visually inspect the counterbore/annulus region of each installed MNSA-2 each refueling outage for leakage. In addition, Entergy will also inspect the surrounding areas for any leakage from other sources of boric acid that could impact the integrity of a MNSA-2. If leakage that occurred during the operating cycle is discovered, Entergy will remove the MNSA-2 and inspect it and the surrounding pressurizer surface for corrosion.

During plant startup following each refueling outage, Entergy will perform a VT-2 inspection in accordance with ASME Section Xl for Examination Category B-P. A VT-1 inservice inspection in accordance with ASME Section Xl for Examination Category B-G-2 will be performed once during each 10-year interval.

Any leakage condition would be entered into and processed through the corrective action program.

V. CONCLUSION 10CFR50.55a(a)(3) states:

'Proposed alternatives to the requirements of (c), (d), (e), (f), (g), and (h) of this section or portions thereof may be used when authorized by the Director of the Office of Nuclear Reactor Regulation. The applicant shall demonstrate that:

(i) The proposed alternatives would provide an acceptable level of quality and safety, or (ii) Compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety."

The request for the alternative is to use the improved design of the MNSA-2 permanently as an alternative to removing the MNSA-2 and performing a permanent welded repair.

Additionally, Entergy requests authorization to consider all future MNSA-2 installations as permanent repairs.

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, , , - 11.7,- V

- -:41 t '.', .;I In Reference 14, the NRC informed Entergy of its position in the event a licensee decides to keep a MNSA in service beyond two operating cycles., The NRC specified information that should be provided to justify such a request. This inforimation has been incorporated into this request. To aid the staff in its review of the request, Entergy has included, in Appendix 2, a cross-reference that identifies the location of the requested information.

Entergy believes that the proposed alternative provides an acceptable level of quality and safety because:

• The design of the MNSA-2 is in accordance with ASME Section III, 1989 Edition, NB-3200. The analysis includes provisions for fatigue and assurances that stresses do not exceed Code allowables. Additionally, significant prototype testing (seismic, hydrostatic, and thermal cycling) has been completed that demonstrates functionality and leak tightness during conditions of operations that are representative of ANO-2.

• Modification of the pressurizer has been analyzed in accordance with the original Construction Code [ASME Section III, 1968 Edition through and including the Summer 1970 Addenda (Reference 3)]. The analysis included fatigue, reinforcement requirements for the tapped holes and counterbores, and assurance that stresses do not exceed Code allowables.

• Methods of analysis, materials, and fabrication meet ASME Section III, Subsection NB. This is comparable to the original methods of analysis, materials and fabrication used for the pressurizer.

• The non-Code portions of the MNSA-2 that perform a safety-related function are provided under a program meeting 10CFR50 Appendix B.

• Prior to installation of the MNSA-2, the machined counterbore in the pressurizer base material will be boroscopically inspected to ensure that it is free of "foil" material that could cause improper sealing against the OD of the nozzle.

• After installation, the MNSA-2 will be pressure tested and inspected (uninsulated) for leakage to ensure quality of installation and leak tightness.

Therefore, Entergy requests that the NRC staff authorize this request pursuant to 10 CFR 50.55a(a)(3)(i).

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- CLM LlW EM UaVWFAT0

=oCEJT VYAdoM IC w

-DC.1.9 -

Heater Sleeve MNSA-2 FIGURE 1 16 of 26

Typical Side Shell MNISA-2 FIGURE 2 17 of 26

ANO2-R&R-002, Rev. I APPENDIX I CORROSION ISSUES WITH MNSA-2 MATERIALS 18 of 26

Appendix 1 to ANO2-R&R-002, Rev. 1 REQUEST FOR ALTERNATIVE ANO2-R&R-002, Rev. 1 APPENDIX I CORROSION ISSUES WITH MNSA-2 MATERIALS This appendix summarizes corrosion issues associated with the application of MNSA-2 for small diameter Alloy 600 nozzle repair. The materials of interest are the carbon or low alloy steel used in the components with the defective nozzles, the stainless steels used for the MNSA-2, the fastener material used to attach the MNSA-2 to the component, and the Alloy 600 nozzles that may be repaired.

Corrosion of Carbon/Low Alloy Steel: Assuming a repaired nozzle has a through-wall crack, the crevice between the Alloy 600 nozzle and the pipe/pressurizer will, under worst-case conditions, fill with aerated borated water. The crevice environment will be a stagnant solution that cannot be replenished except perhaps during shutdowns when the reactor coolant system (RCS) is drained. Thus, the concentration of boric acid will not exceed that of the primary coolant at the beginning of a fuel cycle. The corrosion of carbon and low alloy steels in this situation has been previously addressed, most notably by Reference 1, which estimated an overall corrosion rate for these materials using available laboratory corrosion data from tests in aerated and deaerated solution at 100IF to over 6000F assuming plants operated for 88% of the time, were in outages for 10% of the time and were in start-up conditions for 2% of the time. Reference 1 analyses estimated, for small diameter Alloy 600 nozzles and heater sleeves in Combustion Engineering (CE) plants, the amount of material that could be lost by corrosion before ASME Code limits would be exceeded. Corrosion rate data and the bounding allowable material loss calculations were used to estimate repair lifetimes for hot leg pipe nozzles of 76 years, for pressurizer nozzles of 56 years and for heater sleeves of 196 years. Thus, the Reference 1 calculations support a conclusion that carbon and low alloy steel corrosion in the crevice region is not an issue.

Stress Corrosion Cracking of Carbon and Low Alloy Steels: The repaired nozzles will have cracks in the Alloy 600 nozzles or the partial penetration weld metals that will remain in place after the repair is completed. Since residual stresses from the welding will remain, these cracks may continue to propagate through the nozzle/weld metal by a stress corrosion mechanism to the carbon or low alloy steel base metal. Reference 1 indicated that further growth into the base metals by stress corrosion cracking (SCC) is not likely because the low primary side oxygen levels in PWRs will result in corrosion potentials below the critical cracking potentials for these materials in high temperature water.

Stress Corrosion Cracking of MNSA-2 Fasteners: The fasteners attaching the MNSA-2 to the components are SA-453 grade 660 (A-286 stainless steel) which is a precipitation hardened alloy used in applications where corrosion resistance comparable to 300 series stainless steels but higher strength is required. Laboratory tests and field experience have shown A-286 to be susceptible to SCC in a PWR environment when highly stressed (References 2 and 3). Hot headed bolts are more susceptible to SCC than bolts machined from heat-treated bar stock. The MNSA-2 fasteners will be machined from bar stock and thus will be less susceptible to SCC. More importantly, the MNSA-2 fasteners will be external to the RCS and thus not exposed to primary coolant. SCC does not occur in the absence of an 19 of 26

Appendix 1 to ANO2-R&R-002, Rev. 1 aggressive environment. If the primary Grafoil seal were to leak (unlikely since it will be live-loaded during service), the secondary inner and outer seals divert leakage away from the fasteners and prevent exposure to borated water and steam. If the leakage is not channeled away from the fasteners, a wetting and drying condition could result in concentration of boric acid. Laboratory tests indicate that A-286 is resistant to SCC in highly concentrated boric acid solutions (Reference 4). The Aerospace Structural Metals Handbook indicates A-286 is susceptible to SCC in saturated lithium chloride solutions and that anodic polarization further reduces times to cracking in these solutions. The alloy is also susceptible to cracking in boiling sodium chloride solutions and is also susceptible to intergranular corrosion in strong acid solutions such as nitric- hydrofluoric. In the MNSA-2 application, the A-286 will not experience environments comparable to these. Thus, concern about anodic polarization is not warranted. Leakage is a condition that will require repair and will be apparent from boric acid accumulation. This condition will not persist for more than one fuel cycle (24 months maximum) before the leak will be repaired. Thus, SCC of the A-286 is not an issue for the MNSA-2 application.

Corrosion Near the ComDonent OD Surface: If the MNSA-2 primary seal leaks, leakage into the crevice formed by the MNSA-2 and the component could wet the stainless steel MNSA-2 and the carbon and low alloy steel component material. The leak-off connection may permit the ingress of oxygen into the crevice between the seals resulting in an aerated environment. A more likely scenario is that water/steam escaping via the leak-off line will force oxygen from the line and oxygen in the crevice will be consumed by corrosion of the carbon or low alloy steel. The environment in such a situation will probably be similar to that resulting from primary coolant leakage into CRDM crevices. An expert's panel formed to address the issue of SCC growth in CRDM materials has concluded that the environment in such a crevice will be either hydrogenated superheated steam or normal PWR primary water.

Further the panel, on the basis of MULTEQ calculations of the concentration process, concluded that there would not be a significant shift in crevice pH from that of primary water.

The leak-off line will indicate leakage, thus leakage should not persist for more than one cycle. A minor amount (several mils maximum) of carbon/low alloy steel corrosion, as described above, may occur. General corrosion of the SS will be negligible. Since the SS in the crevice region will be in compression, SCC will not occur. The Grafoil seal material has low leachable chlorides (< 50 ppm), and because of leakage via the leak-off line, the level of chlorides will not accumulate to the level where significant pitting will occur. Thus, corrosion near the component OD surface is not an issue.

Galvanic Corrosion: Galvanic corrosion occurs as the result of differences in electrochemical potential (ECP) between the different parts of a cell in a conductive solution (electrolyte). In this case, the cell parts are the MNSA-2 materials. The material with the highest electrochemical potential corrodes preferentially. In this case, the carbon or low alloy steel would preferentially corrode. Similar combinations of materials have been used in applications requiring periodic inspections and there has not been a history of corrosion. In tests in simulated reactor coolant, low alloy steel specimens coupled to more noble material (Type 304 stainless steel) did not show a significant galvanic effect. The available data do not indicate that galvanic corrosion is not an issue.

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~9  : .

Appendix 1 to ANO2-R&R-002, Rev. I Outside Diameter Initiated Stress Corrosion Cracking of the Alloy 600 Nozzles: The outside diameter of the nozzles will be machined by the machining operation that cuts the counterbore. Any machining operation (cutting with a single point tool, grinding, reaming, etc.) will result in a layer of cold-worked (higher strength) material and a change in surface residual stresses (References 5 and 6). The residual stresses may be tensile or compressive. The layer of cold-work material will be several thousandths of an inch thick. If the part is welded after the machining, residual tensile stresses will result. Because the ccld-worked layer has higher strength than the bulk of the material in the nozzle, the surface residual stresses will be higher than if an annealed material had been welded. The higher stresses could result in early initiation of SCC. However, the additional machining associated with MNSA-2 installation is not expected to have an adverse effect on the SCC susceptibility of the nozzles for the following reasons:

(1) The nozzle OD surfaces were previously machined during original fabrication and the additional machining will not significantly alter residual stresses already present.

(2) The nozzles will not be welded. Thus residual stresses such as associated with the partial penetration weld at the pressurizer ID will not be present and SCC initiation is unlikely.

(3) The temperature near the pressurizer OD, the location of the machining, is lower than at the ID surface. Since the temperature is lower and PWSCC is a thermally activated process, the time to initiate and propagate cracks at the machining location will be significantly longer than the time to initiate the cracks that caused the nozzle to need repair.

SCC of 17-4 pH Stainless Steel: 17-7 pH (not 17-4 pH) stainless steel is used for the inner and outer Belleville washers in the MNSA-2 design. A concern was expressed that the material may be susceptible to SCC when coupled to non 17-7 pH materials based on data in the Aerospace Structural Metals Handbook. A review of drawing E-MNSA-2-228-002 indicates that the washers are in contact only with Type 304 or A-286 stainless steels that are very similar in composition to 17-7 pH. The differences in composition are not sufficient to cause a significant galvanic effect. Further, the washers are normally exposed to the containment environment and only if there is a leak is there any potential for exposure to an aqueous environment, in this case steam. Additionally, the leak-channeling feature of the MNSA-2s should divert leakage away from the Belleville washers. The temperatures of the washers (< 3500F) is sufficiently low that SCC is not a concern nor, at this temperature, is the loss of toughness resulting from the 8851F embrittlement phenomenon an issue.

Gross Failure of the Inner Seal: If a major failure of the inner seal occurs, the crevice between the MNSA-2 compression collar and the Alloy 600 nozzle or the crevice between the pressurizer steel and compression collar will receive primary coolant. Primary coolant will escape through the leak off tube into the containment environment, or if the secondary seals were to fail, reactor coolant would leak by the crevice between the compression collar and pressurizer shell. No additional material will be exposed to the steam or steam water mixtures other than those described above and thus, there are no other corrosion issues resulting from this type event.

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Appendix 1 to ANO2-R&R-002, Rev. 1 Summary In summary, there are no corrosion problems associated with the application of the MNSA-2 to Alloy 600 small diameter nozzles. This assessment considered potential corrosion issues associated with the component base metal, the MNSA-2 materials of construction and galvanic effects.

References

1. CE NPSD-1198-P, Rev 00, uLow-Alloy Steel Component Corrosion Analysis Supporting Small-Diameter Alloy 600/690 Nozzle repair/Replacement Programs, CEOG Task 1131",

February, 2001

2. G. 0. Hayner, "Babcock and Wilcox Experience with A-286 Reactor Vessel Intemal Bolting," Proceedings: 1986 Workshop on Advanced High Strength Materials, Paper 5, EPRI NP-6363, May 1989

3. D. E. Powell and J. F. Hall, "Stress Corrosion Cracking of A-286 Stainless Steel in High temperature Water", Improved Technology for Critical Bolting Applications, PMC - Vol. 26, ppl5-22, 1986

4. J. Gorman, "Materials Handbook for Nuclear plant Pressure Boundary Applications", EPRI TR-199668-SI, December 1997 (Draft).

5. CE NPSD-659-P, 'Additional Pressurizer Heater Sleeve Examinations CEOG Task 636",

September 1991.

6. P. Berge, D. Buisine and A. Gelpi, 'Surface Preparation and Stress Corrosion Cracking Models", Presented at the 13' International Corrosion Congress, November 25-29,1996, Melbourne, Australia.

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ANO2-R&R-002, Rev. 1 APPENDIX 2 NRC ANALYSIS & INSPECTION CRITERIA 23 of 26

Appendix 2 to ANO2-R&R-002, Rev. 1 REQUEST FOR ALTERNATIVE ANO2-R&R-002, Rev. I APPENDIX 2 NRC ANALYSIS & INSPECTION CRITERIA In a letter to Entergy Operations, Inc. (Entergy) dated December 5, 2003, the NRC informed Entergy of its position in the event a licensee decides to keep a MNSA in service beyond the period for which temporary approval has been granted. (This period is two operating cycles for ANO-2). The NRC specified information that should be provided to justify such a request.

This information has been incorporated into this request. To aid the staff in its review of this request, Entergy has provided below references that identify the location of the requested information.

Analysis of Pressure Boundary Component The qualification by analysis of the pressure boundary component to which the mechanical nozzle seal assembly (MNSA) is attached by threaded bolts or tie-rods should be based on the calculation of the primary and secondary membrane, bending, and shear stresses calculated from a detailed 3-D finite element analysis. The finite element model should encompass the instrument or heater nozzle through-wall hole and the adjacent tapped holes, and for MNSA-2, the machined counterbore within the nozzle hole.

The qualification should include and be based on the following:

• A list of all plant unique pressure boundary design conditions and operating transients, showing operating pressure, mean wall temperature, and wall temperature gradient, for the pressure boundary component.

This information is contained in Attachment C of Westinghouse Design Report DAR-CI-02-2, Addendum to CENC-1224 Analytical Report for Arkansas Nuclear One Unit 2 Pressurizer, Sections 6.2 and 6.3.

• Detailed calculation of the load in the highest-loaded bolts or tie-rods, resulting from preloading, maximum operating loads, including seismic loads, and accounting for non-linear loading and unloading load-deformation characteristics of the gasket and Belleville washer packs.

This information is contained in Section 2.0 and Attachments A and B of Design Report DAR-CI-02-2.

• Demonstration that the primary and secondary stresses resulting from the finite element analysis meet the ASME Section III NB-3200 stress intensity limits and appropriate special stress limits, under all design loading and service condition mechanical and thermal transients, including the effects on the tapped holes due to the highest bolt or tie-rod loads, and demonstration that the Class 1 fatigue analysis of the pressure boundary will not exceed the Code prescribed cumulative usage factor limit of 1.0 for the life of the plant.

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Appendix 2 to ANO2-R&R-002, Rev. 1 This information is contained in Section 2.0 and Attachment C of Design Report DAR-CI-02-2.

e Demonstration that there is no interaction between adjacent pressure boundary regions where MNSAs are mounted.

This information is contained in Attachment C of Design Report DAR-CI-02-2.

£ ASME Section III minimum wall thickness requirements at the deepest point in the counterbore should be met.

This information is contained in Attachment C of Design Report DAR-CI-02-02, which addresses reinforcement calculations.

• Demonstration that the ASME Section III NB-3300 area reinforcement requirements are met.

This information is contained in the following sections of Design Report DAR-CI-02-2:

o Sections 2.2.2 and 2.4.2 o Section 6.3.2 of Attachment C o Reconciliation of the owner's construction code and the replacement code.

This information is contained in Attachment D of Design Report DAR-CI-02-2.

Inservice Inspection Identify what inservice inspection (ISI) program will be implemented to ensure that the structural and leakage integrity of the MNSA will be maintained throughout the licensed life of the facility. The proposed program should include consideration of the potential for leakage from the MNSA, as well as the potential for leakage from other sources which could impact the integrity of the MNSA. The proposed program should address the type of inspections (e.g., a visual examination VT-2 with insulation removed), inspection scope, periodicity of inspections, inspection qualification, and inspection acceptance criteria.

Identify what ISI program will be implemented to ensure that the structural integrity of the MNSA bolting and threaded holes in the component to which the MNSA is attached will be maintained throughout the licensed life of the facility. The proposed inspections should be designed to detect cracking of the bolting and in the threaded holes due to fatigue, stress corrosion cracking, etc. Disassembly of the MNSA in order to conduct the inspections should be considered. The proposed program should address the type of inspections, inspection scope, periodicity of inspections, inspection qualification, and inspection acceptance criteria.

Identify what ISI program will be implemented to ensure that corrosion detrimental to the structural integrity of the component to which the MNSA is attached will not occur due to exposure of low alloy/carbon steel material in the bore of the penetration throughout the licensed life of the facility. The proposed program should address the type of inspections, inspection scope, periodicity of inspections, inspection qualification, and inspection acceptance criteria.

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Appendix 2 to ANO2-R&R-002, Rev. 1 ISI activities associated with the MNSA-2 are discussed in Section IV.E of this request. In addition, a detailed assessment of the MNSA-2 metallic components as related to general corrosion, stress corrosion cracking of nozzles and fasteners, galvanic effects, crevice corrosion, and surface pitting is contained in Appendix I of this request 26 of 26

ENCLOSURE 2 CNRO-2004-0001 6 LICENSEE-IDENTIFIED COMMITMENTS

I

- I. Z Enclosure 2 to CNRO-2004-0001 6 Page 1 of 2 LICENSEE-IDENTIFIED COMMITMENTS TYPE (Check one) SCHEDULED ONE-TIME CONTINUING COMPLETION COMMITMENT ACTION COMPLIANCE DATE

1. The new machining procedure will include a Prior to installing step requiring a boroscopic examination to a MNSA.

ensure that unmachined "foil" is not present in the counterbore.

2. The bolting and tie rods of the MNSA-2 are During considered ASME Section Xl, Examination installation of a Category B-G-2, Item No. B7.50 bolting. As MNSA.

required by IWA-4820, a VT-1 pre-service inspection will be performed in accordance with IWB-2200.

3. In accordance with ASME Section Xl, Until the MNSA IWA-4710(c), mechanical joints made in the is removed from installation of pressure retaining replacements service.

shall be pressure tested. During plant startup, the test will be performed in conjunction with a VT-2 inspection at normal operating pressure with the test temperature determined in accordance with the pressure and temperature limits as stated in the ANO-2 Technical Specifications.

4. Entergy inspects components in the reactor Until the MNSA coolant system (RCS) in accordance with NRC is removed from Generic Letter 88-05, Boric Acid Inspection service.

Program. As part of this inspection program, Entergy will visually inspect the counterbore/annulus region of each installed MNSA-2 each refueling outage for leakage. In addition, Entergy will also inspect the surrounding areas for any leakage from other sources of boric acid that could impact the integrity of a MNSA-2.

If leakage that occurred during the operating cycle is discovered, Entergy will remove the MNSA-2 and inspect it and the surrounding pressurizer surface for corrosion.

5. During plant startup following each refueling Until the MNSA outage, Entergy will perform a VT-2 inspection in is removed from accordance with ASME Section Xl for service.

Examination Category B-P.

to CNRO-2004-0001 6 Page 2 of 2 TYPE (Ch ck one) SCHEDULED ONE-TIME CONTINUING COMPLETION COMMITMENT ACTION COMPLIANCE DATE

6. A VT-1 inservice inspection in accordance with / Until the MNSA ASME Section Xi for Examination Category is removed from B-G-2 will be performed once during each service.

10-year interval.