ML021290428

Relief Request, Related to the First Interval Inservice Inspection Program for Metal Containment

ML021290428
Person / Time
Site:	Prairie Island
Issue date:	06/11/2002
From:	Kim T NRC/NRR/DLPM/LPD3
To:	Nazar M Nuclear Management Co
References
TAC MB2784, TAC MB2785
Download: ML021290428 (20)

Text

June 11, 2002 Mr. Mano Nazar Site Vice President Prairie Island Nuclear Generating Plant Nuclear Management Company, LLC 1717 Wakonade Drive East Welch, MN 55089

SUBJECT:

PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 -

EVALUATION OF RELIEF REQUEST RELATED TO THE FIRST INTERVAL INSERVICE INSPECTION PROGRAM FOR METAL CONTAINMENT (TAC NOS. MB2784 AND MB2785)

Dear Mr. Nazar:

By letter dated August 14, 2001, the Nuclear Management Company, LLC, submitted the subject request for relief associated with the first interval inservice inspection program for metal containment at the Prairie Island Nuclear Generating Plant, Units 1 and 2.

Based on the information provided in the relief request (Relief Request Nos. MC-1 through MC-7), the staff has concluded that the licensees proposed alternatives will provide an acceptable level of quality and safety for Relief Request Nos. MC-4 and MC-7. Therefore, the proposed alternatives are authorized pursuant to 10 CFR 50.55a(a)(3)(i). For Relief Request Nos. MC-1, MC-2, MC-3, MC-5, and MC-6, the staff has concluded that compliance with the code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety, and that the licensees proposed alternatives will provide reasonable assurance of containment pressure integrity. Therefore, these proposed alternatives are authorized pursuant to 10 CFR 50.55a(a)(3)(ii). The alternatives are authorized for the first 120-month interval containment inservice inspection program. The staffs evaluation supporting the subject relief request is enclosed.

Sincerely,

/RA/

Tae Kim, Senior Project Manager, Section 1 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-282 and 50-306

Enclosure:

Safety Evaluation cc w/encl: See next page

ML021290428 Prairie Island Nuclear Generating Plant, Units 1 and 2 cc:

J. E. Silberg, Esquire Tribal Council Shaw, Pittman, Potts and Trowbridge Prairie Island Indian Community 2300 N Street, N. W. ATTN: Environmental Department Washington, DC 20037 5636 Sturgeon Lake Road Welch, MN 55089 Site Licensing Manager Prairie Island Nuclear Generating Plant Mr. Roy A. Anderson Nuclear Management Company, LLC Executive Vice President and 1717 Wakonade Drive East Chief Nuclear Officer Welch, MN 55089 Nuclear Management Company, LLC 700 First Street Adonis A. Neblett Hudson, WI 54016 Assistant Attorney General Office of the Attorney General Nuclear Asset Manager 455 Minnesota Street Xcel Energy, Inc.

Suite 900 414 Nicollet Mall St. Paul, MN 55101-2127 Minneapolis, MN 55401 U.S. Nuclear Regulatory Commission Resident Inspectors Office 1719 Wakonade Drive East Welch, MN 55089-9642 Regional Administrator, Region III U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, IL 60532-4351 Administrator Goodhue County Courthouse Box 408 Red Wing, MN 55066-0408 Commissioner Minnesota Department of Commerce 121 Seventh Place East Suite 200 St. Paul, MN 55101-2145 March 2002

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO RELIEF REQUEST ASSOCIATED WITH FIRST-INTERVAL INSERVICE INSPECTION PROGRAM FOR METAL CONTAINMENT NUCLEAR MANAGEMENT COMPANY, LLC PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 DOCKET NOS.: 50-282 AND 50-306

1.0 INTRODUCTION

In the Federal Register dated August 8, 1996 (61 FR 41303), the Nuclear Regulatory Commission (NRC) amended its regulations to incorporate by reference the 1992 edition with 1992 addenda of Subsections IWE and IWL of Section Xl of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code). Subsection IWE provides the requirements for inservice inspection (ISI) of Class CC (concrete containment),

and Class MC (metallic containment) components of light-water cooled power plants.

Subsection IWL provides the ISI requirements of Class CC components.

The regulations require that ISI of certain Code Class MC and CC components be performed in accordance with Section XI of the ASME Code, and applicable addenda, except where alternatives have been authorized or relief has been requested by the licensee and granted by the Commission pursuant to paragraphs (a)(3)(i), (a)(3)(ii), or (g)(6)(i) of 10 CFR 50.55a. In proposing alternatives or requesting relief, the licensee must demonstrate that: (1) the proposed alternatives provide an acceptable level of quality and safety; (2) compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety; or (3) conformance is impractical for its facility. Section 50.55a authorizes the Commission to approve alternatives and to grant relief from ASME Code requirements upon making necessary findings.

By letter dated August 14, 2001, the Nuclear Management Company, LLC (the licensee),

proposed several alternatives to the requirements of Subsection IWE of Section XI of the ASME Code for Prairie Island Nuclear Generating Plant, Units 1 and 2. The Nuclear Regulatory Commission (NRC) staffs findings with respect to authorizing the alternatives or denying the proposed requests are discussed in this evaluation.

ENCLOSURE

2.0 RELIEF REQUESTS Summary of Relief Requests Relief 10 CFR 50.55a - Recommended Request No. ASME Code Issue Identification NRC Action Remarks IWE/IWL Section MC-1 IWA-2300 Qualification of NDE Personnel (a)(3)(ii) authorized MC-2 Table IWE-2500-1, VT-3 Examination of Seals and (a)(3)(ii) authorized Category E-D, Items Gaskets E5.10 and E5.20 MC-3 Table IWE-2500-1, Torque/Tension Test of Pressure (a)(3)(ii) authorized Category E-G, Item Retaining Bolting E8.20 MC-4 IWE-2200(g) Preservice Examination of New Paint (a)(3)(i) authorized or Coating MC-5 IWE-2500(b) Visual examination of paint and (a)(3)(ii) authorized coatings prior to removal MC-6 IWE-2420(b) and Successive Examination after repairs (a)(3)(ii) authorized IWE-2420(c)

MC-7 Table IWE-2500-1 Visual Examination and Personnel (a)(3)(i) authorized Category E-A, Items Qualification E1.12 and E1.20 2.1 Relief Request No. MC-1 2.1.1 Code Requirements Subarticle IWA-2300, "Qualification of Nondestructive Examination [NDE] Personnel," requires qualification of nondestructive examination personnel to ANSI/ASNT CP-189-1991, "Standard for Qualification and Certification of Nondestructive Testing Personnel," as amended by the ASME Code,Section XI.

2.1.2 Specific Relief Requested Relief is requested from the provisions of Subarticle IWA-2300. This requires NDE personnel to be qualified and certified using a written practice in accordance with CP-189, "Standard for Qualification and Certification of Nondestructive Testing Personnel," as amended by the requirements of Subarticle IWA-2300.

The relief is requested for the first inspection interval of the Containment Inspection Examination Plan for Prairie Island, Units 1 and 2.

2.1.3 Basis for Relief The regulation at 10 CFR 50.55a was amended, as cited in the Federal Register (61 FR 41303), to require the use of the ASME Code,Section XI, 1992 edition, 1992 addenda, when performing containment examinations. In addition to the requirements of Subsection IWE, this also imposes the requirements of Subsection IWA, General Requirements, of the 1992 edition, 1992 addenda of the ASME Code,Section XI.

Subarticle IWA-2300 requires qualification of NDE personnel to CP-189, as amended by Subarticle IWA-2300.

A written practice based on the requirements of CP-189, as amended by the requirements of Subarticle IWA-2300, to implement Subsection IWE duplicates efforts already in place for all other subsections. The Prairie Island, Units 1 and 2, Third 10-Year Inservice Inspection Program is written to meet the 1989 edition of Section XI of the ASME Code with no addenda, along with the 1974, summer 1975 addenda for the extent of examinations for Class 1, Category B-J, items only. Subarticle IWA-2300 of the 1989 edition requires a written practice based on ASNT SNT-TC-1A, "Personnel Qualification and Certification of Nondestructive Testing," as amended by the requirements of Subarticle IWA-2300. Further, Subarticle IWA-2300 of the 1992 edition, 1992 addenda, states, "Certifications based on SNT-TC-1A are valid until re-certification is required."

Visual examination is the primary NDE method required by Subsection IWE. Neither CP-189 nor SNT-TC-1A specifically includes visual examination. Therefore, the code requires qualification and certification to comparable levels as defined in CP-189 or SNT-TC-1A, as applicable, and the licensees written practice. Table IWE-2500-1 may also require ultrasonic thickness examinations. These examinations are relatively simple and do not require any extensive training and qualification program. Therefore, use of CP-189 in place of SNT-TC-1A will not improve the capability of the examination personnel to perform the visual and ultrasonic thickness examinations required by IWE.

Development and administration of a second program would not enhance safety or quality and would serve as a burden, particularly in developing a second written practice, tracking of certifications, and duplication of paperwork. This duplication would also apply to NDE vendor programs. Updating to the 1992 edition, 1992 addenda for Subsections IWB, IWC, etc., would require a similar request for relief.

The licensee requested relief in accordance with 10 CFR 50.55a(a)(3)(ii). Compliance with the requirements of this regulation would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

2.1.4 Alternative Examinations Examinations required by Subsection IWE shall be conducted by personnel qualified and certified to a written practice based on SNT-TC-1A and to the current Code of record for IWB, IWC, etc.. Visual examination personnel receive specific training on conducting containment examinations.

2.1.5 Staff Evaluation of Relief Request No. MC-1 In lieu of using the requirements of Section IWA-2300 of the 1992 edition and addenda of the ASME Code,Section XI, that examination personnel be qualified and certified in accordance with CP-189, Standard for Qualification and Certification of Nondestructive Testing Personnel, the licensee proposes to conduct examinations with personnel qualified and certified to a written practice based on SNT-TC-1A and the 1989 edition of the ASME Code,Section XI (with no addenda).

The staff recognizes that under the licensees inspection program, examinations are to be conducted by personnel qualified and certified to a written practice based on SNT-TC-1A in accordance with the 1989 edition of the ASME Code,Section XI. The staff also realizes that a written practice based on the requirements of CP-189, as amended by the requirements of Section IWA-2300, to implement Sections IWE and IWL duplicates efforts already in place for all other subsections. To develop and to administrate a second program would constitute a burden, particularly in developing a second written practice, tracking of certifications, and duplication of paperwork. In addition, Section IWA-2300 of the 1992 edition, 1992 addenda, of the ASME Code,Section XI, states that certification based on SNT-TC-1A are valid until re-certification is required.

On the basis discussed above, the staff concludes that developing and implementing two qualification programs for NDE personnel would result in hardship to the licensee without a compensating increase in the level of quality and safety. The alternative proposed by the licensee will provide adequate qualifications for personnel performing containment examinations. Therefore, the request for relief is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) on the basis that compliance with the specific requirements of the Code would result in a significant hardship without a compensating increase in the level of quality and safety.

2.2 Relief Request No. MC-2 2.2.1 Code Requirements The ASME Code,Section XI, 1992 edition, 1992 addenda, IWE-2500, Table IWE-2500-1, Examination Category E-D, Items E5.10 and E5.20, requires seals and gaskets on airlocks, hatches, and other devices to be visually examined (VT-3) once each interval to assure containment leak-tight integrity.

2.2.2 Specific Relief Requested Relief is requested from performing the Code-required visual examination (VT-3) on the seals and gaskets of Class MC pressure-retaining components as specified above. The relief is requested for the first inspection interval of the Containment Inspection Examination Plan for Prairie Island, Units 1 and 2.

2.2.3 Basis for Relief The regulation at 10 CFR 50.55a was amended in the Federal Register (61 FR 41303) to require the use of the 1992 edition, 1992 addenda, of the ASME Code,Section XI, when performing containment examinations. The penetrations discussed below contain seals and gaskets.

Electrical Penetrations There are two types of electrical penetrations utilized at Prairie Island, Units 1 and 2. The majority of the electrical penetrations utilize a metal canister which is welded to a containment penetration nozzle. Conductors passing through the canisters are sealed with a potting compound to assure leak-tight integrity. The canisters are pressurized with dry nitrogen to maintain and monitor integrity and prevent moisture intrusion into the penetration. A second type uses a header plate which is bolted to the containment penetration nozzle flange with redundant metal O-rings between the header plate and flange face. Modules through which electrical conductors pass are installed in the header plate. Feed-through modules, through which the electrical conductors pass, utilize a series of compression fittings that are welded to the header plate. The seals and gaskets on these two types of electrical penetrations cannot be inspected without disassembly of the electrical penetration to gain access to the seals and gaskets.

Mechanical Penetrations Penetrations for personal and maintenance airlock, equipment hatch, fuel transfer tube, service air, containment vent and purge, heating steam, and containment pressurization lines utilize gaskets or O-rings to seal the door or flanges to ensure leak-tight integrity. The personnel and maintenance airlock also contains other gaskets and seals, such as the handwheel shaft seals, electrical penetrations, and equalizing pressure connections which require disassembly to gain access to the gaskets and seals.

Seal and gasket joints receive a 10 CFR Part 50, Appendix J, test. As noted in 10 CFR Part 50, Appendix J, the purpose of Type B tests is to measure leakage of containment or penetrations whose design incorporates resilient seals, gaskets, sealant compounds, and electrical penetrations fitted with flexible metal seal assemblies. Examination of seals and gaskets require the joints, which are proven adequate through Appendix J testing, be disassembled. For electrical penetrations, this would involve (1) a pre-maintenance Appendix J test (as found), (2) de-termination of cables at electrical penetrations if enough cable slack is not available, (3) disassembly of the penetration enclosure or joint, (4) removal and/or examination of the seals and gaskets, (5) reassembly of the penetration enclosure or joint, (6) re-termination of the cables if necessary, (7) post-maintenance testing of the cables, and (8) a post-maintenance Appendix J test of the penetration (as left). The work required for the mechanical penetrations would be similar except for the determination, re-termination, and testing of cables. This imposes the risk that equipment could be damaged.

The 1992 edition, 1993 addenda of Section XI, IWE 2500-1, Category E-D, Note 1, states that seal or gasket connections need not be disassembled solely for performance of examinations.

However, without disassembly, most of the surface of the seals and gaskets would be inaccessible. The requirement to examine seals and gaskets has been removed in the 1998 edition of the ASME Code,Section XI.

Some penetrations are routinely disassembled during maintenance outages, when necessary, and at each refueling outage. Prior to final closure, the sealing surfaces of these penetrations are inspected for damage which could prevent sealing. The seals and gaskets are inspected and/or replaced as required. This is accomplished by plant procedures or work orders.

Type B testing is also completed upon final assembly and prior to start-up. Since the Type B test will assure leak-tight integrity of primary containment, the performance of additional visual inspections would not increase the level of safety or quality.

2.2.4 Alternative Examinations The leak-tightness of seal and gasket joints will be tested in accordance with 10 CFR Part 50, Appendix J. This testing is performed at least once each inspection interval. No additional alternative examinations to the visual examination (VT-3) of the seals and gaskets will be performed.

2.2.5 Staff Evaluation of Relief Request No. MC-2 IWE-2500, Table-2500-1, requires the seals and gaskets on airlock, hatches, and other devices to be visually examined (VT-3) once each interval to assure containment leak-tight integrity.

The licensee proposes to use its existing primary containment leakage testing program for leakage testing containment penetrations in accordance with 10 CFR 50, Appendix J, Option B, in lieu of a VT-3 visual examination.

In its request, the licensee stated that because the seals and gaskets associated with these penetrations are not accessible for examination when the penetration is assembled, containment penetration seals and gaskets must be disassembled and re-assembled for the purpose of performing the VT-3 visual examination. The activities (a pre-maintenance Appendix J test, de-termination of cables at electrical penetrations if enough cable slack is not available, disassembly of the joints, removal and examination of the seals and gaskets, re-assembly of the joints, re-termination of the cables if necessary, post-maintenance testing of cables, and post-maintenance Appendix J testing of the penetration) associated with a VT-3 visual examination would introduce the possibility of component damage that would not otherwise occur. The periodical test of penetrations in accordance with 10 CFR Part 50, Appendix J, will detect local leakage at containment peak accident pressure and measure leakage across the leakage-limiting boundary of containment penetrations whose design incorporates resilient seals, gaskets, sealant compounds, and electrical penetrations fitted with flexible metal seal assemblies. If unacceptable leakage is identified during the test, corrective measures would be taken and components would be retested.

Also, the staff finds that the ASME Code,Section XI, 1992 edition, 1993 addenda, states that sealed or gasketed connections need not be disassembled solely for performance of examinations. Requiring the licensee to disassemble components for the sole purpose of

inspecting seals and gaskets would place a significant hardship on the licensee without a compensating increase in the level of quality and safety.

The licensee proposed Appendix J, Option B (Type B tests), as an alternative to the requirements of Table IWE-2500-1, Category E-D (VT-3 examinations on seals and gaskets of containment penetrations). The licensee states that some of the penetrations are routinely disassembled during maintenance outages, when necessary, and at each refueling outage.

Prior to final closure, the sealing surfaces of these penetrations are inspected for damage that could prevent sealing. The seals and gaskets are inspected and/or replaced as required. This is accomplished by plant procedures or work orders. Appendix J Type B testing is also completed upon final assembly and prior to startup. Since the Type B test will assure leak-tight integrity of the primary containment, the performance of additional visual inspections would not increase the level of safety or quality.

On the basis discussed above, the staff concludes that the alternative proposed by the licensee will provide reasonable assurance of the functionality and integrity of the containment penetration seals and gaskets during the testing required by 10 CFR Part 50, Appendix J. The proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) on the basis that compliance with the specific requirements of the Code would result in hardship without a compensating increase in the level of quality and safety.

2.3 Relief Request No. MC-3 2.3.1 Code Requirements The ASME Code,Section XI, 1992 edition, 1992 addenda, Table IWE-2500-1, Examination Category E-G, "Pressure Retaining Bolting," Item E8.20, requires that torque and tension test shall be performed on pressure retaining bolts.

2.3.2 Specific Relief Requested Relief is requested from the ASME Code,Section XI, 1992 edition, 1992 addenda, Table IWE-2500-1, Examination Category E-G, Item E8.20. Table IWE-2500-1 requires a bolt torque or tension test on bolted connections that have not been disassembled and reassembled during the inspection interval.

The relief is requested for the first inspection interval of the Containment Inspection Examination Plan for Prairie Island, Units 1 and 2.

2.3.3 Basis for Relief Bolt torque and tension testing is required on bolted connections that have not been disassembled and reassembled during the inspection interval. De-termination of the torque or tension value would require the bolting be un-torqued and re-torqued or re-tensioned. Both Prairie Island, Units 1 and 2, have 22 bolted penetrations of which 19 are pressure seating and 3 are pressure unseating. Of the pressure unseating penetrations, all are routinely disassembled within the interval.

The regulation at 10 CFR 50.55a was amended to require the use of the 1992 edition, 1992 addenda, of the ASME Code,Section XI, when performing containment examinations.

Each containment penetration receives an Appendix J, Type B, test in accordance with the specified testing frequencies. As noted in 10 CFR Part 50, Appendix J, the purpose of Type B tests is to measure leakage of containment penetrations whose design incorporates resilient seals, gaskets, sealant compounds, and electrical penetrations fitted with flexible metal seal assemblies. For pressure seating, the performance of the Type B test itself proves that the bolt torque or tension remains adequate to provide a leak rate that is within acceptable limits. The torque or tension value of bolting only becomes an issue if the leak rate is excessive. For pressure unseating penetrations, the performance of the Type B test may not prove that the bolt torque or tension remains adequate. Inspection of pressure unseating penetrations during an Appendix J Type A test would prove that the bolt torque or tension remains adequate to provide a leak-tight penetration.

Once a bolt is torqued or tensioned, it is not subject to dynamic loading that could cause it to experience significant change; therefore re-torquing is unnecessary. Leak rate testing per Appendix J and visual inspection are adequate to demonstrate that the design function is met.

Torque or tension testing is not required for any other ASME Code Class 1, 2, or 3 bolted connections or their supports as part of the inservice inspection program.

The requirement to perform bolt torque or tension tests was removed in the 1997 addenda of ASME Code,Section XI. This addenda has been approved by the Main Committee and was issued in the 1998 edition of ASME Code,Section XI.

2.3.4 Alternate Examinations The following examinations and tests required by Subsection IWE ensure the structural integrity and the leak-tightness of Class MC pressure-retaining bolting, and, therefore, no additional alternative examinations are proposed.

1. Exposed surfaces of bolted connections shall be visually examined in accordance with requirements of Table IWE-2500-1, Examination Category E-G, "Pressure Retaining Bolting," Item No. E8.10, and

2. Bolted connections shall meet the pressure test requirements of Table IWE-2500-1, Examination Category E-P, "All Pressure Retaining Components," Item E9.40.

Additionally, inspections for excessive leakage of pressure unseating penetrations will be performed during Type A testing.

2.3.5 Staff Evaluation of Relief Request No. MC-3 ASME Code,Section XI, 1992 edition, 1992 addenda, Table IWE-2500-1, Examination Category E-G, Item E8.20, requires bolt torque or tension testing on bolted connections that have not been disassembled and reassembled during the inspection interval. This examination is used to aid in the determination that leak-tight seals exist and that the structural integrity of the subject bolted connections is maintained. The licensee proposes to use the Appendix J Type B test together with visual examinations as an alternative to the Code requirement to verify the integrity of penetrations with bolted connections.

The staff realizes that bolt torque or tension testing on bolted connections that have not been disassembled and reassembled during the inspection interval would require the bolting be un-torqued and then re-torqued or re-tensioned, whereas the leak testing as required by 10 CFR Part 50, Appendix J, would adequately verify the leak-tight integrity of the containment.

The staff also realizes that compliance with ASME Code requirements will cause a hardship or unusual difficulty because un-torquing and subsequent re-torquing bolted connections involve unnecessary radiation exposure and costs to perform the work without a compensating increase in the level of quality and safety. In addition, the staff finds that the alternative approach proposed by the licensee (the Type B test required by 10 CFR Part 50, Appendix J, to verify the leak-tight integrity of bolted connections for containment vessel leak-tight integrity together with visual examinations) will provide reasonable assurance of the containment pressure boundary integrity. On this basis, the staff concludes that the alternative proposed by the licensee is authorized pursuant to 10 CFR 50.55a(a)(3)(ii).

2.4 Relief Request No. MC-4 2.4.1 Code Requirements ASME Code,Section XI, 1992 Edition, 1992 Addenda, Subsection IWE-2200(g), requires that when paint or coatings are reapplied, the condition of the new paint or coating shall be documented in the preservice examination records.

2.4.2 Specific Relief is Requested The licensee requested relief from the requirement to perform a preservice inspection of new paint or coatings. The relief is requested for the first inspection interval of the Containment Inspection Examination Plan for Prairie Island, Units 1 and 2.

2.4.3 Basis for Relief The paint or coatings are not part of the containment boundary under the current Code rules as they are not associated with the pressure containing function of the component (paragraph NE-2110(b) of ASME Section III). Paint and coatings on the containment pressure boundary were not subject to the Code rules when they were originally applied and not subject to ASME Code,Section XI, rules for repair and replacement in accordance with IWA-4111(b)(5).

The requirement to perform a preservice inspection when paint or coating is reapplied was removed from ASME Code,Section XI, 1998 edition, Subsection IWE. However, since degradation of the coating could impact the structural integrity of the containment, the adequacy of the applied coating is verified through inspections performed by the Prairie Island, Units 1 and 2, Coating Maintenance Program.

Recording the condition of reapplied coating in the preservice record does not substantiate the containment structural integrity. Should deterioration of the coating occur in the reapplied area, that area would require additional evaluation regardless of the preservice record. Even though the licensee has been performing preservice inspection of reapplied coatings as required by IWE, recording the condition of the new coating in the preservice records would not increase the level of quality or safety.

In SECY 96-80, "Issuance of final amendment to 10 CFR 50.55a to incorporate by reference the ASME Boiler and Pressure Vessel Code (ASME Code),Section XI, Division 1, Subsection IWE and IWL," dated April 17, 1996, the response to comment #3.2 regarding IWE-2200(g) states: In the NRC's opinion, this does not mean that a visual examination must be performed with every coating application. A visual examination of the topcoat to determine the soundness and the condition of the topcoat should be sufficient." This process is accomplished through inspections performed by the Prairie Island, Units 1 and 2, Coating Maintenance Program. This program is described in a November 11, 1998, response to Generic Letter 98-04. In this program, the condition of the coatings are examined every 18 months for the containment interior. These periodic examinations will identify evidence of flaking, blistering, peeling, discoloration, or other signs of coating distress indicative of degradation of the coating system.

The requirement to perform a preservice examination when paint or coatings are reapplied has been removed from the 1998 edition of the ASME Code,Section XI.

2.4.4 Alternate Examinations Reapplication of paint or coatings on the containment will be examined in accordance with the Prairie Island, Units 1 and 2, Coating Maintenance Program. Although repairs to paint or coating are not subject to the repair/replacement rules of ASME Code,Section XI (Inquiry 97-22), repair to the primary containment boundary, if required, would be conducted in accordance with the ASME Code,Section XI, rule.

2.4.5 Staff Evaluation of Relief Request No. MC-4 In lieu of meeting the ASME Code,Section XI, 1992 edition, 1992 addenda, Subsection IWE-2200(g), requirements to perform a preservice inspection of new paint or coatings, the licensee proposed to examine the paint and coatings in accordance with the Prairie Island, Units 1 and 2, Coating Maintenance Program. This program meets the guidance of NRC Generic Letter 98-04. In this program, the condition of the coatings are examined every 18 months for the containment interior. These periodic examinations will identify evidence of flaking, blistering, peeling, discoloration, or other signs of coating distress indicative of degradation of the coating system. In addition, the staff realizes that in SECY 96-80, the response to comment #3.2 regarding IWE-2200(g) states that in the NRC's opinion, this does not mean that a visual examination must be performed with every coating application. A visual examination of the topcoat to determine the soundness and the condition of the topcoat should be sufficient. This process is currently accomplished through inspections performed by the licensee as part of the Prairie Island, Units 1 and 2, Coating Maintenance Program.

Coating used for new applications or repair/replacement activities are procured from a vendor with a quality assurance program meeting the applicable requirements of 10 CFR Part 50, Appendix B. The qualification testing and evaluation of the coating used for new applications or repair/replacement activities inside the containment are performed in accordance with the ANSI N101.2-1972.

The staff finds that the alternative program, as described by the licensee, will provide an acceptable level of quality and safety for protecting the containment surfaces of the Prairie Island, Units 1 and 2, containments. On this basis, the staff concludes that the licensees alternative coating program is authorized pursuant to 10 CFR 50.55a(a)(3)(i).

2.5 Relief Request No. MC-5 2.5.1 Code Requirements ASME Code,Section XI, 1992 edition, 1992 addenda, Subarticle IWE-2500(b), requires that when paint or coatings are to be removed, the paint or coatings shall be visually examined in accordance with Table IWE-2500-1 prior to removal.

2.5.2 Specific Relief Requested The licensee requested relief from the requirement of Subarticle IWE-2500(b). IWE-2500(b) requires that when paint or coatings are to removed, the paint or coating shall be visually examined in accordance with table IWE-2500-1 prior to removal. The relief is requested for the first inspection interval of the Containment Inspection Examination Plan for Prairie Island, Units 1 and 2.

2.5.3 Basis for Relief Paint and coatings are not part of the containment pressure boundary under current Code rules as they are not associated with the pressure containing function of the component (Paragraph NE-2110(b) of ASME Section III). Paint and coatings on the containment pressure boundary were not subject to the Code rules when they were originally applied and not subject to ASME Code,Section XI, rules for repair and replacement in accordance with IWA-4111(b)(5). The requirement to perform a visual examination prior to removal of paint or coatings was removed from the ASME Code,Section XI, 1998 edition, Subsection IWE. Degradation or discoloration of the paint or coating materials on the containment would be an indicator of potential degradation of the containment boundary. Additional measures would have to be employed to determine the nature and extent of any degradation, if present.

Even though the licensee has been performing inspections prior to removal of coating as required by IWE, the application of ASME Code,Section XI, rules for examination of paint or coatings prior to their removal when unrelated to an ASME Code,Section XI, repair or replacement activity, is a burden without a compensating increase in quality or safety. The relief is requested in accordance with 10 CFR 50.55a(a)(3)(ii). The Prairie Island, Units 1 and 2, Coating Maintenance Program currently provides an adequate level of quality and safety.

2.5.4 Alternate Examinations The condition of the containment base material will be verified by a visual examination prior to the application of new paint or coatings as required by the Prairie Island, Units 1 and 2, Coating Maintenance Program and the requirements of Examination Category E-A. If degradation is identified, additional measures will be applied to determine if the containment boundary has been affected. Repairs to the primary containment boundary, if required, will be conducted in accordance with ASME Section XI Code rules.

2.5.5 Staff Evaluation of Relief Request No. MC-5 As discussed in the evaluation of Relief Request MC-4, the staff finds that the Prairie Island, Units 1 and 2, Coating Maintenance Program is adequate for monitoring the proper removal of the old paint and application of new coatings. To perform additional examinations prior to removal of the old paint and to document the condition of the old paint or coatings, (in addition to the licensees program subjected to the quality assurance requirements of 10 CFR Part 50, Appendix B), would result in hardship to the licensee without a compensating increase in the level of quality and safety. On this basis, the staff concludes that the alternative coating program proposed by the licensee is authorized pursuant to 10 CFR 50.55a(a)(3)(ii).

2.6 Relief Request No. MC-6 2.6.1 Code Requirements Paragraphs IWE-2420(b) and IWE-2420(c) of the 1992 edition, 1992 addenda of the ASME Code,Section XI, requires that when component examination results require evaluation of flaws, evaluation of areas of degradation, or repairs in accordance with Article IWE-3000, "Acceptance Standards," and the component is found to be acceptable for continued service, the areas containing such flaws, degradation, or repairs shall be reexamined during the next inspection period listed in the schedule of the inspection program of Paragraph IWE-2411, "Inspection Program A," or Paragraph IWE-2412, "Inspection Program B," in accordance with Table IWE-2500-1, Examination Category E-C.

2.6.2 Specific Relief Requested The licensee requested relief from the requirement of Paragraphs IWE-2420(b) and IWE-2420(c) to perform successive examination of repairs. The relief is requested for the first inspection interval of the Containment Inspection Examination Plan for Prairie Island, Units 1 and 2.

2.6.3 Basis for Relief The regulation at 10 CFR 50.55a was amended to require the use of the 1992 edition, 1992 addenda, of the ASME Code,Section XI, when performing containment examinations.

The purpose of a repair is to restore the component to an acceptable condition for continued service in accordance with the acceptance standards of Article IWE-3000.

Paragraph IWA-4150, Verification of Acceptability," requires the owner to conduct an evaluation of the suitability of the repair including consideration of the cause of failure.

If the repair has restored the component to an acceptable condition, successive examinations are not warranted. If the repair was not suitable, then the repair does not meet code requirements and the component is not acceptable for continued service. Neither Paragraph IWB-2420(b), Paragraph IWC-2420(b), nor Paragraph IWD-2420(b) requires a repair to be subject to successive examination requirements. Furthermore, if the repair area is subject to accelerated degradation, it would still require augmented examination in accordance with Table IWE-2500-1, Examination Category E-C. The successive examination of repairs in accordance with Paragraphs IWE-2420(b) and IWE-2420(c) constitutes a burden without a compensating increase in quality or safety.

In SECY 96-080, "Issuance of Final Amendment to 10 CFR 50.55a to Incorporate by Reference the ASME Boiler and Pressure Vessel Code (ASME Code),Section XI, Division 1, Subsection IWE and Subsection IWL," dated April 17, 1996, the response to comment # 3.3 states: "The purpose of IWE-2420(b) is to manage components found to be acceptable for continued service (meaning no repair or replacement at this time) as an Examination Category E-C component ... if the component had been repaired or replaced, then the more frequent examination would not be needed."

2.6.4 Alternate Examinations Successive examinations in accordance with Paragraphs IWE-2420(b) and IWE-2420(c) are not required for repairs made in accordance with Article IWA-4000.

2.6.5 Staff Evaluation of Relief Request No. MC-6 The staff realizes that when repairs are complete, IWA-4150 requires licensees to evaluate the suitability of the repair. When a repair is required because of failure of an item, the evaluation shall consider the cause of failure to ensure that the repair is suitable. Considering that the failure mechanism is identified and corrected as required and the repair receives preservice examinations, as required, the proposed alternative will provide reasonable assurance of structural integrity. In doing this, the requirements of successive examinations are deemed to be unnecessary and this results in hardship a burden without a compensating increase in level of quality or safety.

Furthermore, IWB-2420(b), IWC-2420(b), and IWD-2420(b) do not require the successive inspection of repairs for ASME Code Class 1, 2, and 3 components as required in IWE-2420(b) for ASME Code Class MC components. Therefore, the request for relief is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) on the basis that compliance with the specific requirements of the Code would result in hardship without a compensating increase in the level of quality and safety.

2.7 Relief Request No. MC-7 2.7.1 Code Requirements ASME Code,Section XI, 1992 edition, 1992 addenda, Table IWE-2500-1, Category E-A, Containment Surfaces, Items E1.12 and E1.20, requires that a 100-percent VT-3 visual examination be performed at the end of each interval. The visual examination to be performed for accessible surface areas of the containment vessel and vent system.

2.7.2 Specific Relief Requested The licensee requested relief from ASME Code,Section XI, 1992 edition, 1992 addenda, Table IWE-2500-1, Category E-A, "Containment Surfaces," Items E1.12 and E1.20, which requires that a 100-percent VT-3 visual examination be performed at the end of each interval.

The relief is requested for the first inspection interval of the Containment Inspection Examination Plan for Prairie Island, Units 1 and 2.

2.7.3 Basis for Relief Visual examination of 100 percent of the accessible surfaces of the containment vessel and the vent system would be required at the end of the interval. Code Case N-601, Extent and Frequency of VT-3 Visual Examination for Inservice Inspection of Metal Containment,Section XI, Division 1," provides an alternative to the Code requirements of performing 100 percent of Items E1.12 and E1.20 at the end of the interval. The Code Case states, The VT-3 examinations in Table IWE-2500-1, Examination Category E-A, Containment Surfaces, may be performed at any time during interval, provided the requirements for successive inspections in IWE-2420 are met.

Scaffolding is erected near the containment shell for other activities such as maintenance and inservice inspection of piping etc. It would be advantageous to utilize this scaffolding to directly examine the containment surfaces. The successive inspection requirements of IWE-2420 will be maintained with the existing schedule.

Pursuant to 10 CFR 50.55a(a)(3)(i), relief is requested on the basis that the proposed alternative criteria of Code Case N-601 provide an acceptable level of quality and safety.

2.7.4 Alternate Examinations The VT-3 visual examinations of the accessible surface areas of the containment vessel will be performed in accordance with Code Case N-601. This code case provides an alternative that allows visual examinations to be performed at any time during the interval, provided the requirements for successive inspections stated in IWE-2420 are met.

2.7.5 Staff Evaluation of Relief Request No. MC-7 In lieu of meeting the requirements of Table IWE-2500-1 (1992 Edition), Category E-A, Items E1.12 and E1.20, that 100 percent of VT-3 visual examinations shall be performed at the end of the interval, the licensee proposed to perform the VT-3 visual examinations on accessible surface areas of the containment structure in accordance with Code Case N-601.

The staff finds that to perform visual examinations on the accessible surfaces of the containment structure during the course of inspection interval (based on the recommendation by Code Case N-601 that the VT-3 examinations in Table IWE-2500-1, Category E-A be performed at any time during the interval of inspection) will be more beneficial and efficient than following the requirements Table IWE-2500-1 (1992 Edition), because in doing this, the integrity of the containment can be better monitored between the 10 CFR Part 50, Appendix J, testing, and the visual examinations required by Table IWE-2500-1. On this basis, the staff concludes that the alternative proposed by the licensee based on Code Case N-601 provides an acceptable level of quality and safety, and is authorized pursuant to 10 CFR 50.55a(a)(3)(i).

3.0 CONCLUSION

Based on the information provided in the relief requests (Relief Requests MC-1 through MC-7),

the staff concludes that for Relief Request Nos. MC-4 and MC-7, the licensees proposed alternatives will provide an acceptable level of quality and safety. Therefore, the proposed alternatives are authorized pursuant to 10 CFR 50.55a(a)(3)(i). For Relief Request Nos. MC-1,

MC-2, MC-3, MC-5, and MC-6, the staff concludes that compliance with the code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety, and that the licensees proposed alternatives will provide reasonable assurance of containment pressure integrity. Therefore, these proposed alternatives are authorized pursuant to 10 CFR 50.55a(a)(3)(ii).

The alternatives are authorized for the first 120-month inspection interval of the Containment Inspection Examination Plan for Prairie Island, Units 1 and 2.

Principal Contributor: G. Bedi Date: June 11, 2002