ML20212D128

Safety Evaluation Supporting Proposed Alternatives CRR-03, 05,08,09,10 & 11

ML20212D128
Person / Time
Site:	Peach Bottom
Issue date:	09/17/1999
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20212D121	List: ML20212D119 ML20212D128
References
NUDOCS 9909230016
Download: ML20212D128 (27)

Text

'

pn %q

, [c?

& I ) 1, t UNITED STATES E

NUCLEAR REGULA'10RY COMMISSION i i! wassinovow. o.c. cosvami

,  % .... /

SAFETY EVALUATION OF PROPOSED ALTERNATIVES TO ASME SECTION XI REQUIREMENTS FOR CONTAINMENT INSERVICE INSPECTION NUMBERS CRR-01 THROUGH CRR-11 PECO ENERGY COMPANY PEACH BOTTOM ATOMIC POWER STATION UNITS 2 AND 3 i o

DOCKET NOS. 50-277 AND 50-278 1

In the Federal Reaister dated August 8,1996 (61 FR 41303), the U.S. Nuclear Regulatory Commission (NRC) amended its regulations to incorporate by reference the 1992 edition with 1992 addenda of Subsections IWE and IWL of Section XI of the ASME Boiler and Pressure Vessel Code (ASME Code). Subsections IWE and IWL provide the requirements for inservice inspection (ISI) of Class CC (concrete containment), and Class MC (metallic. containment) of i light-water cooled power plants. The effective date for the amended rule was September 9, l 1996, and it requires the licensees to incorporate the new requirements into their ISI plans and '

to complete the first containment inspection by September 9,2001. However, a licensee may propose alternatives to or submit a request for relief from the requirements of the regulation pursuant to 10 CFR 50.55a(a)(3) and (g)(5).

By the letters dated February 17,1999 (Reference 1) and August 11,1999 (Reference 2), the licensee, PECO Energy Company, proposed several alternatives to the requirements of Subsections IWE and IWL of Section XI of the ASME Code for its Peach Bottom Atomic Power 4 Station (PBAPS), Units 2 and 3. NRC's findings with respect to authorizing the alternatives are discussed in this evaluation.

2.0 EVALUATION OF REllEF REQUESTS I 2.1 Relief Request CRR-01 2.1.1 Code Requirements IWE-2500, Table IWE-2500-1 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.

Enclosure 9909230016 990917 PDR ADOCK 05000277 P PDR j

p . ,

l l- .

\

2.1.2 Specific Relief Requested l Relief is requested from performing the Code-required visual examination, VT-3, on the above identified metal containment seals and gaskets.

2.1.3 Basis for Relief 10 CFR 50.55a was amended in the Federal Register (61FR41303) to require the use of the 1992 Edition,1992 Addenda, of Section XIwhen performing containment examinations. Seals and gaskets receive a 10 CFR 50 Appendix J test. As noted in 10 CFR 50 Appendix J, the purpose 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. Although not required by the

! Code, practical examination considerations of seals and gaskets require the joints, which are proven adequate through Appendix J iesting, to be disassembled. For electrical penetrations, this would involve a pre-maintenance Appendix J test, de-termination of cables at electrical penetrations if enough cable slack is not available, disassembly of the joint, removal and examination of the seals and gaskets, reassembly of the joint, re-termination of the cables if necessary, post maintenance testing of the cables, and a post maintenance Appendix J test of the penetration. The work required for the containment hatches would be similar except for the de-termination, re-termination, and testing of cables. This imposes the risk that equipment could be damaged.

The 1992 Edition,1993 Addenda, of Section XI recognizes that disassembly of joints to perform these examinations is not warranted. Note 1 in Examination Category E-D was modified in the 1995 Edition of Section XI to state that sealed 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.

For those penetrations that are routinely disassembled, a Type B test is required upon final assembly and prior to start-up. Since the Type B test will assure the leak tight integrity of primary containment, the perforrnance of the visual examination would not  ;

increase the level of safety or quality.

Seals and gaskets are not part of the containment pressure boundary under current Code rules (NE-1220 (b)). When the airlocks and hatches containing these materials are tested in accordance with 10 CFR 50, Appendix J, degradation of the se1rrtMjhsket material would be revealed by an increase in the leakage rate. Corrective measures would be applied and the component retested. Repair or replacement of seals and gaskets is not subject to Code (1992 Edition,1992 Addenda) rules in accordance with Paragraph IWA4111 (b)(5) of ASME Section XI.

The visual examination of seals and gaskets in accordance with IWE-2500, Table IWE-2500-1 is a burden without any compensating increase in the level of safety or quality.

This requirement was removed in the 1997 Addenda of ASME Section XI, and is not included in the 1998 Edition.

L j

F .

Relief is requested in accordance with 10 CFR 50.55a(a)(3)(ii). Compliance with the specified requirements of this section would result in hardship or unusual difficulty l without a compensating increase in the level of quality and safety. Testing the seals and gaskets in accordance with 10 CFR Part 50, Appendix J, will provide adequate assurance of the leak-tight integrity of the seals and gaskets.

2.1.4 Proposed Alternative Requirements

~

The leak-tightness of seals and gaskets will be tested in accordance with 10 CFR 50, Appendix J. No additional alternatives to the visual examination, VT-3, of the seals and gaskets will be performed. I l

l 2.1.5 Staff Evaluation of CRR-01 i

The licensee proposes to use, in lieu of performing the VT-3 examinations for containment i penetration seals and gaskets, the current program for leakage testing containment penetrations in accordance with 10 CFR Part 50, Appendix J.

The staff does not agree with the statement in the licensee's request that the penetration seals and gaskets are not part of the containment pressure boundary. However, the staff agrees with l the licensee's justification that because the seals and gaskets associated with these l penetrations are not accessible for examination when the penetration is assembled, containment penetrations seals and gaskets must be disassembled and re-assembled for the purpose of performing the VT-3 visual examination. These activities (disassembly and re-assembly of seals and gaskets) associated with a VT-3 visual examination would introduce the possibility of component damage that would not otherwise occur. The periodic test of penetrations in accordance with 10 CFR Part 50, Appendix J, will detect local leaks and

measure leakage across the leakage-limiting boundary of containment penetrations whose l 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.

l The staff realizes that the 1992 edition,1993 Addenda, of ASME Code,Section XI has l recognized that disassembly of joints for the sole purpose of performance of the visual examination is unwarranted. Also, as stated in the " Basis for Relief" above, this requirement l was removed in the 1997 Addenda of ASME Section XI, and is not included in the 1998 Edition.

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 quality and safety.

l On the basis discussed above, the staff concludes that the alternative proposed by the licensee will provide reasonable assurance of the leak-tight integrity of the containment penetration seals and gaskets during the Type B testing required by 10 CFR Part 50, Appendix J. Therefore, 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. ,

\

l l

J

ab 2.2 Relief Request CRR-02 2.2.1 Code Requirements Subarticle IWA-2300 of the 1992 Edition,1992 Adaenoa of ASME Section XI, requires qualification of nondestructive examination (NDE) personnel to CP-189, as amended by f ASME Section XI.

2.2.2 Specific Relief Requested Relief is requested from the provisions of Subarticle IWA-2300, " Qualification of Nondestructive Examination Personnel." 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 this Division.

2.2.3 Basis for Relief j 10 CFR 50.55a was amended in the Dderal Register (61FR41303) to require the use of the 1992 Edition,1992 Addenda, of Seebon XI when performing containment examinations. A written practice based on the requirements of CP-189, as amended by the requirements of the Subarticle IWA 2300, to implement Subsections IWE and IWL duplicates efforts already in place for all other subsections.10 CFR 50.55a references j

the 1989 Edition of ASME Section XI for all other subsections. Subarticle IWA-2300 of the 1989 Edition requires a written practice based on SNT-TC-1 A, as amended by the requirements of Subarticle IWA-2300. Further, Subarticle IWA-2300 of the 1992 Edition,1992 Addenda, states, " Certification based on SNT-TC-1 A are valid until recertification is required." Visual examination is the primary nondestructive i examination (NDE) method required by Subsections IWE and IWL. Neither CP-189 nor SNT-TC-1 A specifically includes visual examination; thus, the Code requires qualification and certification to comparable levels as defined in CP-189 or SNT-TC-1 A, as applicable, and the Employer's written practice. Development and administration of a second program would not enhance safety or quality and would constitute 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 CP-189 as referenced in the 1992 Edition,1992 Addenda, for Subsections lWB, IWC, etc., would require a similar request for relief.

Relief is requested in accordance with 10 CFR 50.55a(a)(3)(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.

2.2.4 Proposed Alternative Examination Examinations required by Section IWE shall be conducted by personnel qualified and certified to a written practice based on SNT-TC-1 A in accordance with the 1989 Edition of ASME Section XI, which is the Code of record for Subsections IWB, IWC, LWD and IWF at PBAPS for the current (i.e., third) interval.

'D 2.2.5 Staff Evaluation of CRR-02 in lieu of using the requirements of Section IWA-2300 of the 1992 Edition and Addenda of ASME Section XI that examination personnel be qualified and certified in accordance with ANSl/ASNT 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-1 A and the 1989 Edition of ASME Section XI for the first ten-year containment inspection interval beginning November 5,1998.

The staff recognizes that under the licensee inspection program, examinations are to be conducted by personnel qualified and certified to a written practice based on SNT-TC-1 A in accordance with the 1989 Edition of ASME 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 implement a second program would not enhance safety or quality and would constitute a burden, particularly in developing a second written practice, tracking of certifications, and duplication of paperwork. In addition, Section IWA-2300 of Sc 1992 Edition,1992 Addenda, states that certification based on SNT-TC-1 A is valid until recertification is required. Also, in the licensee's request and the August 11,1999, submittal (Reference 2), PECO stated that this relief is requested for the first ten-year containment inspection interval of the PBAPS Units 2 and 3 ISI program. This program began at November 5,1998, and will conclude on November 4,2008, at which time a future version of the ASME Section XI Code is expected to be incorporated by reference into the regulations.

On the basis discussed above, the staff concludes that developing and implementing two qualification programs for NDE personnel would result in burden on the licensee. The alternative proposed by the licensee will provide adequate qualifications for personnel performing containment examinations. Therefore, 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 CRR-03 2.3.1 Code Requirements ASME 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.

2.3.2 Specific Relief Requested Relief is requested from the requirement to pedorm a preservice inspection of new paint or coatings.

a }

2.3.3 Basis for Relief Paint and coatings are not part of the containment pressure boundary under current Code rules because they are not associated with the pressure retaining function of the component (Paragraph NE-2110 (b) of ASME Section Ill). Neither paint nor coatings contribute to the structuralintegrity or leak tightness of the containment. Furthermore the paint and coatings on the containment pressure boundary were not subject to Code rules when they were originally applied and are not subject to ASME XI rules for repair or replacement in accordance with IWA-4111(b)(5). The adequacy of applied coatings is verified through the PECO Energy Coatings Program for Nuclear Facilities.

Recording the condition of reapplied coating in the preservice record does not substantiate the containment structuralintegrity. Should deterioration of the coating in the reapplied area occur, the area will require additional evaluation regardless of the preservice record. Recording the condition of new paint or coating in the preservice records does not increase the level of quality and safety of the containment.

SECY 96-080, response to Comment 3.2 about IWE-2200(g) states, "In the NRC's opinion, this does not mean that a visual examination must be performed with every application of paint or coating. A visual examination of the topcoat to determine the soundness and the condition of the topcoat should be sufficient." This is currently accomplished through the PECO Energy Coatings Program for Nuclear Facilities.

Recording the condition of new paint or coatings in the preservice record is redundant to the requirements of the PECO Energy Coatings Program for Nuclear Facilities, and as such is an administrative burden without a compensating increase in safety.

Relief is requested in accordance with 10 CFR 50.55a(a)(3)(i). The PECO Energy Coatings Program for Nuclear Facilities currently provides an adequate level of quality and safety.

{

l 2.3.4 Proposed Alternative Criteria l

The paint and coatings in the containment will be examined in accordance with the PECO Energy Coatings Program for Nuclear Facilities. If degradation of the coating is l identified, additional measures will be applied to determine if the containment pressure  !

boundary is affected. Although repairs to paint or coatings are not subject to the repair / replacement rules of ASME X' ('nquiry 97-22), repairs to the primary containment boundary, not including coatings, if required, would be conducted in accordance with ASME Section XI Code rules.

2.3.5 Staff Evaluation of CRR-03 The staff does not agree with the licensee's perception that the quality and integrity of the paint applied to the containm=+ *wd relevant to the containment's functionalintegrity. In Tabie 3 of the Final Rule {SECY 96-080), there are a number of examples where the containment integrity was found in question because of the degradation of the applied paint and coating, and corrosion of base material.

In response to the staff's concern regarding the PBAPS coating program (Reference 2), the licensee indicated that the containment coating is applied and inspected in accordance with the

r l PBAPS Units 2 and 3,10 CFR Part 50, Appendix B, Quality Assurance Program, which is l described in Section D.11 of the PBAPS Units 2 and 3 Updated Safety Analysis Report. The following requirements are applicable for coatings applied to interior surface of the containment vessel:

i

, (1) The quality assurance requirements of Sections 6 and 7 of ASTM D3843-93 applicable l to the coating manufacturer are imposed on the coating manufacturer through the procurement process.

(2) Coating application procedures are developed based on the manufacturefs recommendations for the application of the selected coating systems.

l (3) Coating applicators are qualified to demonstrate their ability to satisfactorily apply the coatings in accordance with the manufacturer's recommendations.

(4) Quality Verification (OV) personnel qualified in accordance with ANSI N45.2.6-1978 and ASTM D4537-91 perform inspections to verify conformance to the coating application procedures and perform examinations of previously applied coatings. Section 10 of ASTM D3843-93 is used as a guideline in the establishment of the inspection program.

(5) Alternatively, personnel qualified in accordance with ASNT SNT-TC-1 A (8/84) supplemented with appropriate coating training, perform examinations of previously l applied coatings.

(6) Documentation demonstrating conformance to the above in maintained.

A visual coating examination of accessible and immersed surfaces cf the drywell and suppression / torus surfaces is perfmmed at least every 4 to 6 years in accordance with 10 CFR 50.65," Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants." These periodic examinations willidentify evidence of flaking, blistering, peeling,

)

l discoloration, or other signs of coating distress which might be indicative of degradation of the containment structuralintegrity.

This program is presently being evaluated by the licensee against the recommendations of Information Notice (IN) 97-13, " Deficient Conditions Associated with Protective Coatings at Nuclear Power Plants," and the Electric Power Research Institute (EPRI) Plant Supporting Engineering TR-109937," Guideline on Nuclear Safety-Related Coatings." Changes to improve this program will be implemented as necessary.

The staff finds that the alternative program, as stated by the licensee, will provide an acceptable level'of quality and safety for protecting the inside steel surfaces of the PBAPS containment. On this basis, the staff concludes that the licensee's alternative coating program is authorized pursuant to 10 CFR 50.55a(a)(3)(i).

l l

. l i

l l

8 2.4 Relief Request CRR-04 i

2.4.1 Code Requirements 1

I ASME Section XI,1992 Edition,1992 Addenda, Subarticle lWE-2500(b) requires that -

l 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.

2.4.2 Specific Relief Requested Subarticle IWE-2500(b) requires that when paint or coatings are to be removed, the paint or coatings shall be visually cxamined in accordance with Table IWE-2500-1 prior to removal.

2.4.3 Basis for Relief 10 CFR 50.55a was amended in FR 61FR41303 to require the use of the 1992 Edition, 1992 Addenda, of Section XI when performing containment examinations. Paint and coatings are not part of the containment pressure boundary under current Code rules because they are not associated with the pressure retaining function of the component ,

l (Paragraph NE-2110 (b) of ASME Section lil). The interiors of containment are painted to prevent rusting. Neither paint nor coatings contribute to the structural integrity or leak tightness of the containment. Furthermore, the paint and coatings on the containment i pressure boundary were not subject to Code rules when they were originally applied and are not subject to ASME XI rules for repair or replacement in accordance with l IWA4111(b)(5). Degradation or discoloration of the paint or coating materials on containment could be an indicator of potential degradation of the containment pressure boundary. Additional measures would have to be employed to determine the nature and extent of any degradation, if present. The application of ASME XI rules for removal of paint or coatings when unrelated io a Section XI repair or replacement activity, is a burden without a compensating increase in quality or safety.

Relief is requested in accordance with 10 CFR 50.55a(a)(3)(i). The PECO Energy coatings program for nuclear facilities currently provides an adequate level of quality and safety.

2.4.4 Proposed Altemative Criteria The paint and coatings in the containment will be examined in accordance with the PECO Energy Coatings Program for Nuclear Facilities. If degradation of the coating is identified, additional measures will be applied to determine if the containment pressure boundary is affected. Although repair to paint or coatings are not subject to the repair / replacement rules of ASME Section XI (inquiry 97-22), repairs to the primary l containment boundary, not including coatings, ti requitoo, wouia De concluded in accordance with ASME Section XI Code rules.

L

I -

, 2.4.5 Staff Evaluation of CRR-04 As discussed in the evaluation of Relief Request CRR-03, the staff finds that the PBAPS coating 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 licensee's 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 acceptable for authorizing the licensee's proposed alternative to the requirement of Subarticle IWE-2500(b) of the Code pursuant to 10 CFR 50.55a(a)(3)(ii).

2.5 Relief Request CRR-05 l

\

2.5.1 Code Requirements i

Paragraph IWE-5240 of the 1992 Edition,1992 Addenda of ASME Section XI states that the requirements of Paragraph IWA-5240 for visual examination, VT-2, are appliceble j following repair, replacement, or modification. j 2.5.2 Specific Relief Requested Relief is requested from performing the VT-2 visual examination in connection with system pressure testing following repair, replacement or modification under Article IWE-5000. I 2.5.3 Basis for Relief 10 CFR 50.55a was amended in FR 61FR41303 to require the use of the 1992 Edition, 1992 Addenda, of Section XIwhen performing containment examinations. Paragraph IWE-5210 states that except as noted within Paragraph IWE-5240, the requirements of Article IWA-5000 are not applicable to Class MC or Class CC components. Paragraph IWE-5240 states that the requirements of Paragraph IWA-5240 (corrected from IWA-5246 in the 1993 Addenda) for visual examinations are applicable. Paragraph IWA-5240 identifies a "VT-2" visual examination. VT-2 examinations are conducted to detect evidence of leakage from pressure retaining components, with or without leakage collection systems, as required during the conduct of a system pressure test. In addition, personnel performing VT-2 examinations are required to be qualified in accordance with Subarticle IWA-2300 of ASME Section XI.

Table IWE-2500-1, Examination Category E P, identifies the examination method of 10 CFR 50, Appendix J and does not specifically identify a VT-2 visual examination.10 CFR 50, Appendix J provides requirements for testing as well as acceptable leakage l

criteria. These tests are performed by Appendix J " Test" personnel and utilize calibrated equipment to determine acceptability. Additionally,10 CFR 50.55a(b)(2)(x)(E) requires a general visual examination of the containment each period that would identify any structural degradation that may contribute to leakage. A "VT-2" visual examine, tion will not provide additional assurance of safety beyond that of current Appendix J '

practices.

. 1

\

l  !

1 Relief is requested in accordance with 10 CFR 50.55a(a)(3)(i). Pressure testing in l accordance with 10 CFR 50, Appendix J, provides an adequate level of quality.

2.5.4 Proposed Alternative Criteria l Testing shall be conducted in accordance with 10 CFR 50, Appendix J, in lieu of Paragraph IWE-5240 of ASME Section XI. In addition, examinations following repairs or  !

replacements on containment components will be performed in accordance with PECO Energy repair / replacement specification M-679.

l l

2.5.5 Staff Evaluation of CRR-05 '

In lieu of the requirements of Paragraph IWA-5240 of ASME Section XI for the visual examination, VT-2, to be app'ied following repair, replacement or modification, the licensee proposed that testing shall be conducted in accordance with 10 CFR Part 50, Appendix J.

The staff agrees with the licensee's statement that for repairs, replacements or modifications

)

that are performed under ASME Section XI, the applicable construction / installation code NDE I are performed and must meet the acceptance criteria of the construction / installation code.

Also, Table IWE-2500-1 (examination category E-P) requires only an examination method of 10 CFR Part 50, Appendix J, for the containment vessel pressure retaining boundary following i each repair, replacement, or modification and does not specifically identify a VT-2 visual examination, in addition,10 CFR Part 50, Appendix J, provides requirements for testing i including acceptable leakage criteria and the tests are performed by Appendix J " Test" personnel by utilizing calibrated equipment to determine acceptability. Moreover,10 CFR l 50.55a(b)(2)(x)(E) requires a general visual examination of the containment each period that i would identify any structural degradation that may contribute to leakage. Furthermore, as l described in the " Proposed Alternative Criteria" Section of the licensee's request, examinations I l following repairs or replacements on containment components will be performed in accordance I l

with PECO Energy repair-replacement specification M-679. However, the licensee did not j provide any description regarding this specification (e.g., what type of visual examinations are '

to be perfomied).

In response to the above staff's concern (Reference 2), the licensee provided a description of this specification as follows: ,

Specification M-679 concerns the ASME Section XI Repair and Replacement Pro ram.

This program provides the administrative guideline for satisfying the require s of the Section XI Code, as applicable to repairs and replacements of Class 1,2,3 and MC l components and their supports. Sections 8,9 and 10 of this specification address the l

need for satisfying the construction code requirements. Section 12 addresses pressure testing of components following repair or replacement, and Section 13 addresses the preservice inspection (PSI) required for repaired or replaced components. Accordingly, a repair of a Class MC component would be implemented (as required by the repair and replacement program) in accordance with the rules of the original construction code.

After completion of the repair / replacement, the original construction code-required NDE would be performed. Following this, the ASME Section XI requiremer.t for PSI would be performed, in accordance with the containment ISI program. As required by Section XI, the method of inspection for PSI would be the method originally used to detect the

condition which required the repair / replacement, and/or the method required for the subsequent ISI. In the case of Class MC components, this method would normally be the visual (VT-3) method. If the repaired or replaced area was Category E-C,

" Containment Surfaces Requiring Augmented Examination," then the method of inspection for the PSI would be the visual (VT-1) method or ultrasonic testing (UT).

These examinations will confirm the structural integrity of the repaired or replaced area of the containment. Confirmation of leak-tight integrity of the area will hen be verified by a pressure test. The system pressure testing would be conducted, as applicable, in the area of the repair or replacement, per 10 CFR 50, Appendix J. The pressure test would be conducted by personnel trained in the methods of testing the containment vessel, as required by Appendix J, utilizing equipment and procedures routinely used for the periodic pressure testing of the containment. Performance of the visual VT-2 examination, during the conduct of this pressure test, would in most cases be impractical, due to accessibility. Access to perform the visual examination of the repaired / replaced area is normally prohibited by either encapsulation of the pressure test boundary (i.e., local leak rate test) or personnel access restrictions into containment during testing (integrated leak rate test). VT-2 examination of the repaired / replaced area from the outside surface of the containment (during the pressure test) would be meaningful and practicalin some cases. However, many portions of the containment are inaccessible on the outside sudace. Further,10 CFR 50, Appendix J acceptance criteria for the results of the pressure testing assures that the leak tight integrity of the containment vessel will support NRC safety goals.

The above-described examinations and testing assure that the structural integrity and leak tight integrity of the primary containment will be maintained following many repairs or replacements of the pressure boundary. Nevertheless, a VT-2 examination will be performed from the ouiside surface of the containment, whenever access from the outside surface is availai:le in the area of the repair or replacement being pressure tested.

From the discussion above, staff finds that for the surface areas that are accessible during the performance of the pressurp test, the licensee will comply with the requirements of IWE-5240.

The staff also considers the requirements of Table IWE-2500-1 (examination category E-P) and 10 CFR Part 50, Appendix J, to be sufficient to assure the structural integrity and leak-tightness of the containment surfaces that are inaccessible for examination. On this basis, the staff concludes that the alternative examinations proposed by the licensee will provide an acceptable level of quality and safety and, therefore, are authorized pursuant to 10 CFR 50.55s(a)(3)(i).

2.6 Relief Request CRR-06 2.6.1 Code Requirements Paragraphs IWE-2420(b) and IWE-2420(c) of the 1992 Edition,1992 Addenda of ASME 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, 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 or Paragraph IWE-2412, in accordance with Table IWE-2500-1, examination category E-C.

2.6.2 Specific Relief Requested Relief is requested from the requirement of Paragraphs IWE-2420(b) and IWE-2420(c) to perform successive examination of repairs.

2.6.3 Basis for Relief 10 CFR 50.55a was amended in FR 61FR41303 to require the use of the 1992 Edition, 1992 Addenda, of 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 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 j 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.

Repair was deleted in Paragraphs IWE-2420(b) and IWE-2420(c) in the 1997 Addenda of Section XI, and is not included in the 1998 Edition.

In their resolution to public comment # 3.3, the NRC stated, "The purpose nf 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 i examination would not be needed." '

1 Relief is requested in accordance with 10 CFR 50.55a(a)(3)(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.

2.6.4 Proposed Alternative Criteria /

l Successive examinations in accordance with Paragraphs IWE-2420(b) and IWE-5420(c) i are not required for repairs made in accordance with Article IWA-4000.

2.6.5 Staff Evaluation of CR-06 The staff agrees with the licensee's justification that when repairs are complete, IWA-4150 requires licensees to evaluate the suitability of the repair. When a repair is required because of L

i .

)

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 I repair receives preservice examinations, as required, the proposed alternative will provide reasonable assurance of structuralintegrity. In doing this, the hardship associated with the l requirements of successive examinations can be eliminated. Furthermore, IWB-2420(b), IWC- l 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. On this basis, the licensee's proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) that compliance with the specific code requirements would result in ,

hardship without a compensating increase in the level of quality and safety.

2.7 Relief Request CRR-07 2.7.1 Code Requirements 1 ASME Section XI,1992 Edition through the 1992 Addenda, Table IWE-2500-1, Examination Category E-G, Pressure Retaining Bolting, item E8.10, requires that Class MC bolted connections be subject to a VT-1 visual examination.

ASME Section XI,1992 Edition through the 1992 Addenda, Table IWE-2500-1, Examination Category E G, Pressure Retaining Bolting, Item E8.20, requires that Class MC bolted connections be subject to a bolt torque or tension test.

2.7.2 Specific Relief Requested Relief is requested from ASME Section XI 1992 Edition with the 1992 Addenda, Table IWE-2500-1 Examination Category E-G, Pressure Retaining Bolting, items E8.10 and E8.20.

2.7.3 Basis for Relief l

10 CFR 50.55a was amended in FR 61 FR41303 to require the use of the 1992 Edition,  !

1992 Addenda, of Section XI when performing containment examinations. Per the 1992 Edition through 1992 Addenda of ASME Section XI, pressure retaining bolted connections require a VT-1 visual examination. However, ASME Section XI reevaluated this examination requirement during a rewrite of Subsec2n lWE. During the review of examination category E-G examination criteria, the following factors were considered: l (1) Containment surfaces, including bolted connections, are already subject to visual examination in accordance with Table IWE-2500-1, examination category E-A.

(2) Bolted connections in containment are subject to the performance of 10 CFR 50, Appendix J teeing.

(3) Containment botting is not subject to a known degradation mechanism, primarily because it is not in contact with a corrosive environment. There have been no problems with containment bolting identified within the industry.

l

I 1

The conclusion reached by ASME Section XI was that examination category E G examinations on bolted connections were not warranted. In the commentary which accompanied the Subsection IWE rewrite, the following was written:

" Pressure-retaining bolting as a separate category has been deleted, and the examination requirements for pressure-retaining bolting have been consolidated into Category E-A. Examination of pressure-retaining bolting does not require removal or disassembly, and only those exposed surfaces of bolting materials need be examined."

As a result, examination category E-G has been eliminated from Table IWE-2500-1 in the 1998 Ed3 ion of ASME Section XI. "

The performance of visual examinations on bolted connections in accordance with the 1992 Edition through 1992 Addenda of ASME Section XI represents a hardship with no compensating increase in the level of quality and safety. The reexamination of bolted connections that are already examined as part of examination category E-A, and tested in accordance with 10 CFR 50, Appendix J, unnecessarily increases the number of inservice examinations and the associated radiation exposure to personnel, in addition to the visual examination of bolted connections, the 1992 Edition through 1992 Addenda of ASME Section XI requires that bolt torque orlension testing be performed on bolted connections that have not been disassembled and reassembled during the inspection interval. Determination of the torque or tension value would require that the bolting be un-torqued and then re-torqued or re-tensioned. The performance of a 10 CFR 50, Appendix J, Type B test 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.

Once a bolt is torqued or tensioned, it is not subject to dynamic loading that could cause it to experience significant change. Verification of torque or tension values on bolted joints that are proven adequate through Appendix J testing and visual inspection is l adequate to demonstrate that design function is met. Torque or tension testing is not l required on any other ASME Section XI, Class 1,2, or 3 bolted connections or their supports as part of the ISI program.

Relief is requested in accordance with 10 CFR 50.55a(a)(3)(ii). Compliance with the specified requirements of this section would result in hardship or unusual difficulty l without a compensating increase in the level of quality and safety.

l 2.7.4 Proposed Alternative Criteria The following examinations and tests required by Subsection IWE ensure the structural integrity and tha '"Nagss,ah61 ass MC pressure retaining bolting, and, therefore, no additional alternaliv'e examinations are proposed:

(1) Exposed surfaces of bolted connections shall be visually examined in accordance with the requirements of Table IWE-2500-1, Examination Category E-A, Containment Surfaces, and i

(2) Bolted connections shall meet the pressure test requirements of 10 CFR 50, Appendix J.

2.7.5 Staff Evaluation of CRR-07 The licensee proposed two alternatives: (1) in lieu of performing the VT-1 visual examination of the pressure retaining bolting (in accordance with Table IWE-2500-1, examination category E-G, E-8.10), a visualinspection of bolted connections will be performed (in accordance with IWE 3510.1), and (2) in lieu of performing the torque or tension test (in accordance with Table IWE-2500-1, examination category E-G, E-8.20), the leak tight integrity will be verified in accordance applicable requirements of 10 CFR Part 50, Appendix J.

The staff agrees with the licensee that the performance of visual examinations on bolted connections in accordance with the 1992 Edition through 1992 Addenda of ASME Section XI represents a hardship (the reexamination of bolted connections unnecessarily increases the number of inservice examinations and the associated radiation exposure to personnel) with no compensating increase in the level of quality and safety. The staff also agrees with the licensee that the 10 CFR Part 50, Appendix J, requirements together with the visual examination (in lieu of performing the VT-1 visual examination of the pressure retaining botting subject to examination in accordance with Table IWE-2500-1, " Examination Categories,"

Examination Category E-G, " Pressure Retaining Bolting") for evaluating inservice effects that could adversely impact the performance of the bolted connections will ensure the leak-tight integrity of the containment structure with bolted connections.

Furthermore, the staff finds that to perform a bolt torque or tension test on bolted connections that have not been disassembled and reassembled during the inspection interval will cause a hardship without a compensating increase in the level of quality and safety. Determination of the torque or tension value would require that the bolting be un-torqued and then re-torqued or re-tensioned. The staff a so agree with the licensee that the alternate. approach (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) will verify the adequacy of the bolted connections to provide a leak rate that is within acceptable limits.

On this basis discussed above, the staff concludes that the licensee's proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) on the basis that compliance with the specific code requirements would result in hardship without a compensating increase in the level of quality and safety.

2.8 Relief Request CRR-08 ,

2.8.1 Code Requirements ASME Section XI, Table IWE-2412-1 lists the required percentages of examinations that must be performed per period in accordance with inspection Program B. Per the table, the number of examinations to be completed during the first period shall be between 16% and 34%. For the second period, the total number of examinations to be completed shall be betwean 50% and 67%, and by the end of the third period,100% of the examinations for the interval shall be completed.

l

m z

.. \

2.8.2 Specific Relief Requested Relief is requested from the examination percentages listed in Table IWE-2412-1.

2.8.3 Basis for Relief -

Table IWE 2412-1 was originally established such that approximately one third of the non-deferred examinations would be performed each period. The emergence of longer fuel cycles increases the likelihood that one of the periods will only have one refueling outage in it. In addition, efforts to shorten refueling outages have limited the amount of time available to perform examinations. These factors make it difficult to complete the Code-required percentages of examinations in the allotted time.

Code Case N-598 was developed to address this issue. It expands the range of examination completion percentages to allow examinations to be distributed more evenly between outages. This minimizes the need to schedule an excessive number of i examinations during one outage just to meet the percentages required by ASME '

Section XI, Table IWE-2412-1. In addition, Code Case N-598 allows for a more uniform distribution between outages that is more conducive to performing quality examinations.

l During the development of Code Case N 598, two additional factors were considered  !

when evaluating the impact of the Code Case on plant safety. The first was that the q existing tables allow up to 50% of the examinations to be performed in the second and  :

third periods, but only 34% can be performed in the first period. Therefore, the l Inspection Plan B schedule is biased towards delaying examinations until the end of the i interval. The more flexible percentages stated in Code Case N-598 allow for more examinations to be performed earlier in the interval. This should improve safety I because any problems, should they exist, would be detected earlier in the interval.

The second factor that was considered when developing Code Case N-598 was that some minimum amount of examination should be required in each period. To address l this consideration, the Code Case, including Note (1), is structured such that l

examinations will be required during all three periods.

! Due to the factors documented above, PECO Energy considers that the alternative criteria of Code Case N-598 provide an acceptable, or improved, level of quality and I safety.

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

2.8.4 Proposed Attemative Criteria PBAPS Units 2 and 3 will use Code Case N-598 for the required percentages of examinations for all Class MC components. Although Code Case N-598 also addresses Class 1,2 and 3 components and supports, these items are being addressed .in Specification NE-290, Request Number RR-33, and therefore are not within the scope of this request for alternative.

L

F .

?.

( l

~ 2.8.5 Staff Evaluation of CRR-08 In lieu of meeting the equirements of examination percentages for each refueling outage listed in Table IWE-2412-1, the licensee proposed an alternative to use the recommendation of Code Case N-598 for the required percentages of examination for all Class MC components.

The staff finds that the range of examination completion percentages based on Code Case N-598 allows examinations to be distributed more evenly between outages. The staff also finds that the recommendation of Code Case N-598 provides a more uniform distribution between outages that is more conducive to performing examinations. On this basis, the staff concludes that the licensee's alternative criteria based on Code Case N-598 provides an acceptable level of quality and safety, and is authorized pursuant to 10 CFR 50.55a(a)(3)(i).

2.9 Relief Request CRR-09 2.9.1 Code Requirements ASME Section XI,1992 Edition through 1992 Addenda, requires that 100 percent of VT-3 visual examinations be performed at the end of the interval for items E1.12 and E1.20.

2.9.2 Specific Relief Requested Relief is requested from the requirement to perform the VT-3 visual examinations entirely at the end of the interval for items E1.12 and E1.20.

2.9.3 Basis for Relief Code Case N-601, " Extent and Frequency of VT-3 Visual Examination for Inservice inspection of Metal Containment" provides an alternative to the Code requirement to perform 100 percent of the VT-3 examinations on items E1.12 and E1.20 at the end of the interval. PECO Energy feels it is more important to perform visual examinations on the accessible surfaces of the containment structure and vent system during the course of the interval rather than at the end. This way, the integrity of the containment and vent system at PBAPS, Units 2 and 3, can be better monitored between the 10 CFR 50, Appendix J testing, and the visual examinations required by Table IWE-2500-1. The successive inspection requirements of IWE-2420 will be maintained.

Pursuant to 10 CFR 50.55a(a)(3)(i), relief is requested on the basis that the proposed a!ternative provides an acceptable level of quality and safety.

2.9.4 Proposed Alternative Criteria PECO Energy will perform the VT-3 visual examinations on accessible surface areas of  !

l the containment structure and vent system in accordance with Code Case N-601. This code case provides an alternative to perform the visual examinations at any time during j the interval, provided the requirements for successive inspections stated in IWE-2420 '

are met. ,.  ;

e ,

2.9.5 Staff Evaluation of CRR-09 in lieu of meeting the requirements of Table IWE-25001 (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 and vent system in accordance with Code Case N-601.

The staff finds that to perform visual examinations on the accessible surfaces of the containment structure and vent system 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 prudent and efficient than following the requirements Table IWE-2500-1 (1992 Edition), because in doing this, the integrity of the containment and vent system 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 alte native 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).

2.10 Relief Request CRR *.0 2.10.1 Code Requi ements ASME Srction XI,1992 Edition through 1992 Addenda, Subarticle IWE-2500(c)(3) requires one-foot square grids be used when ultrasonic thickness measurements are perfumed on augmented examination surface areas. The number and location of the grids is determined by the owner. Subarticle IWE-2500(c)(4) requires that the minimum wall thickness within each grid be determined.

2.10.2 Specific Relief Requested Relief is requested from the requirement to use one foot square grids for augmented examination areas, and the requirement to determine the minimum wall thicknas within each grid.

2.10.3 Basis for Relief Subarticles IWE-2500(c)(3) and IWE-2500(c)(4) of the 1992 Edition,1992 Addenda of ASME Section XI require that the minimum thickness within each one-foot %%" grid of surface areas requiring augmented examination be marked such that periodic reexamination of the location can be performed. Thickness readings are point readings.

Numerous readings are necessary to identify the minimum thickness within each grid.

l This only identifies the thinnest area. Periodic examination of the minimum thickness l point only monitors that point. It may not be the area that is the most susceptible to l

accelerated degradation.

In Code Case N-605, Table 2500-2, " Ultrasonic Thickness Measurements for Augmented Examination," provides the proposed alternative to the one-foot square grid area required by IWE-2500(c)(3). Table 2500-2 requires examination at the grid

e

'* 4 4

• l 19 intersections. The grid line intersections may not exceed 12 inches, and may be as small as 2 inches.

For a sample area of 50 square feet, Code Case N-605, Table 2500-2 requires a minimum 100 locations be monitored. In this instance, utilizing Table 2500-2 rnonitors more locations than required by IWE-2500(c)(3).

For sample areas greater than 100 square feet, Code Case N-605, Table 2500-2 requires that sufficient points be monitored to ensure at least a 95% confidence level that the thickness of the base metalis reduced by no more than 10% of the nominal  !

plate thickness at 95% of the grid line intersections. Table 2500-2 also requires additional examinations when any measurement reveals that the wall thickness is reduced by more than 10% of the nominal plate thickness.

For all examination areas, should the measurements at a grid line intersection reveal ,

that the base materialis reduced by more than 10% of the nominal plate thickness,  !

Code Case N-605, Table 2500-2 requires that the minimum wall thickness within each  !

adjoining grid be determined. This is similar to the examination requirements of IWE- l 2500(c)(4) except that Table 2500-2 focuses resources on areas which have exhibited  !

degradation rather than areas which have not exhibited degradation. '

The requirements of Code Case N-605 have been incorporated into the rewrite of i Subsection IWE of ASME Section XI. This rewrite has been approved by ASME and is published in the 1998 Edition of Section XI. 1 Relief is requested in accordance with 10 CFR 50.55a(a)(3)(ii). Taking numerous ultrasonic thickness measurements within a grid which had not exhibited degradation  ;

results in hardship or unusual difficulty without a compensating increase in the level of quality and safety. The proposed alternative will maintain an acceptable level of quality and safety.

2.10.4 Proposed Alternative Criteria PECO Energy will use Code Case N-605 to determine examination requirements for ultrasonic thickness measurements on areas requiring augmented examination. l 2.10.5 Staff Evaluation of CRR-10 1 In lieu of meeting ASME Section XI,1992 Edition through 1992 Addenda, Subarticles IWE- 4 2500(c)(3) and (4) that require one-foot square grids be used when ultrasonic thickness measurements are performed on augmented examination surface areas, and the minimum wall thickness within each grid be determined, the licensee proposed to use Code Case N-605 to determine examination requirements for ultrasonic thickness measurements on areas requiring .

augmented examination.  !

Under the application of Code Case N-605 rules (as de, scribed in the licensee's request), Table I 2500-2 requires a minimum 100 locations be monitored for a sample area of 50 square feet.

According to the licensee, utilizing Table 2500-2 monitors more locations than that determined by the owner (required by the IWE-2500(c)(3) rule). For sample areas greater than 100 square I

I, .

~

l feet, Table 2500-2 requires: (a) sufficient locations be monitored to ensure at least a 95 percent confidence level that the thickness of the base materialis reduced no more than 10 percent of the nominal plate thickness at 95 percent of the grid line intersections, and (b) additional examinations be taken when any measurement reveals that the wall thickness is reduced by more than 10 percent of the nominM plate thickness. For all examination areas, Table 2500-2 requires that the minimum wa!I thickness within each adjoining grid be determined, if the measurements at a grid line intersection reveal that the base materialis reduced by more than 10 percent of the nominal plate thickness.

On the basis discussed above, the staff finds that the alternative proposed by the licensee will provide reasonable assurance of the containment (plate) integrity. Therefore, the request for relief is authorized pursuant to 10 CFR 50.55a(a)(3)(i) on the basis that the alternative provides an acceptable level of quality and safety.

2.11 Relief Request CRR-11 2.11.1 Code Requirements ASME Section XI,1992 Edition through 1992 Addenda, paragraph IWE-2500(c) and Table IWE-2500-1, Examination Category E-C, " Containment Surfaces Requiring Augmented Examination," require sJrfaces identified by IWE-1240 to be visually

. examined from both sides when accessible, or examined for wall thinning using an ultrasonic thickness measurement method when only one side is accessible.

2.11.2 Specific Relief Requested Relief is requested from ASME Section XI,1992 Edition through 1992 Addesde, paragraph IWE N0(c) and Table IWE-2500-1, Examination Category E-C, item Nos.

E4.11 and E4.12. j 2.11.3 Basis for Relief i

Pursuant to 10 CFR 50.55a(a)(3)(i), an alternative is being proposed on the basis that it provides an acceptable level of quality and safety. l PECO Energy has been performing and documenting examinations of the wettad and submerged interior surfaces of the suppressbn chamber at PBAPS, Units 2 and 3 since  :

1991. Based on examination results and evaluations, PECO Energy has established an ongoing examination program that demonstrates the integrity of the suppression chamber on both units. This program provides an acceptable alternative to the  !

augmented examination requirements of examination category E-C.

The code allows E-C components to be re categorized as non-E-C after they have remained essentially unchangw roi d..ee consecutive inspection periods. This alternative program will continue to monitor the condition of the surface for the life of the plant.

i l'

L

d ':

i- , , .

l l \

This basis for relief describes the history of the existing exammation program, and the l results of examinations and evaluations which demonstrate that the existing examination program provides an acceptable level of quality and safety.

The interior surfaces of the PBAPS, Unit 2 suppression chamber above the waterline j l were initially primed with an inorganic zine silicate coating (Carboline Co. Carbozine) and finished with a modified epoxy phenolic coating (Carboline Co. Phenolic 368). The

)

) i interior surfaces of the entire PBAPS, Unit 3 suppression chamber and the Unit 2 j suppression chamber below the waterline were coated with Carboline Co. Carbozinc 11 l

only. Suppression chamber interior surfaces below the mean waterline, and one foot t i above, were last recoated in June,1980, for Unit 2, and May,1981, for Unit 3.

In 1991, PECO Energy implemented an examination program for wetted and  ;

submerged surfaces on the interior of the suppression chamber in both units.

Underwater visual examinations were performed on the interior suppression chamber surfaces, and pit depth measurements were taken on one square foot evaluation areas that were selected in each of the 16 bays, based on having the greatest concentration of deep pits, in coniunction with the underwater examinations, ultrasonic thickness measurements were taken on the defined evaluation areas from the outside of the l l suppression chamber and from the inside of the suppression chamber at the pitted I l areas. The internal visual examinations detected numerous small areas of coating l l degradation and associatnd corrosion pits. Evaluation areas, pit locations and pit l l depths were documented. The maximum measured pit depth approached a depth of I l 10% of the shell's wall thickness. Coating repairs were made on the deeper pits.

! Results of the examinations were evaluated in ABB Impell Report No. 03-0670-1360,

" Structural Analysis of the Peach Bottom Torus Shell and Vent System for the Effects of

~ Local and Global Corrosion." This report concluded that the structural integrity of the l

l suppression chamber in both units was maintained, and continued operation was  !

Justified. The report also established an evaluation methodology, acceptance criteria and a recommended reexamination schedule that is based on the diameter and depth of the pits.

1 The control of corrosion in the PBAPS, Units 2 and 3 suppression chambers has been l accomplished by control of impurity levels in the suppression chambers water. Water l with low impurities allows less electron flow and results in a lower general corrosion rate of the metal and slower loss of the protective zinc coating. The limits for the suppression chamber water are:

l Conductivity < 5.0 uS/cm Chlorides < 200 ppb Sulflates < 200 ppb The water quality for each suppression chamber is maintained by a feed and bleed process. The quality of the water is normally maintained well below the established limits as stated above.

I

. ,, =

These chemistry requirements have been in effect since 1991, and are a significant improvement from the actual chemistry preceding 1991. Prior to 1991, the conductivity ranged from 5 to 10 uS/cm.

Based on previous examination results, water chemistry improvements, and recommendations from ABB Impell Report No. 03-0670-1360, PECO Energy has e

developed an examination program for suppression chamber examinations. This program was developed in 1991, prior to the time that containment examinations were mandated by 10 CFR 50.55a (1996). The elements of the examination program are as follows:

(1) Perfcrm a visual examination to assess the general condition of the interior surfaces of the suppression chamber. Specific evaluation areas are selected for examination as determined by the responsible engineer, based on previous examination results and recommandations from ABB Impell Report No. 03-0670-1360. Examinations are focused on those areas having the greatest concentration of deep pits. The examination frequency is dependent on the diameter and depth of the pits.

(2) in conjunction with the visual examination of the evaluation areas, pit depth measurements are taken from the interior of the suppression chamber. These measurements are used to evaluate the acceptability of the pits, as well as to determine pit depth growth rates.

(3) Perform ultrasonic thickness measurements on designated areas in 4 bays from the outside of the suppression chamber. These measurements are performed every third cycle, which is nomirially every 6 years.

(4) Evaluate the pits using ABB impell Report No. 03-0670-1360.

Most recently, suppression chamber examinations were performed in 1997 for PBAPS, Unit 3, and 1998 for PBAPS, Unit 2. Examinations on both suppression chambers indicated that there was very little additional degradation in the shell walls or coatings beyond what was identified in 1991. The average pit depth in both PBAPS, Units 2 and 3 increased by less than 0.003 in. over the six-year period between examinations.

These figures support the conclusion that pit depth growth rates are decreasing and that the next examinations can be on the same,6-year frequency. In addition, the resulting measured annual pit growth rate of 0.0005 tn/ year is a factor of 10 less than the conservative annual growth rate of 0.005 tn/ year assumed in ABB 1mpell Repor1 No.

03-0670-1360. Therefore, the conclusions of the ABB Impell Report are further substantiated. The decrease in pit depth growth rate is attributed to improved chemistry controls placed on the suppression chamber water inventories since 1991.

.M 2.11.4 Proposed AlternaiTveTriteria in lieu of the examination criteria specified in ASME Section XI,1992 Edition through 1992 Addenda, paragraph IWE-2500(c) and Tcble IWE-2500-1, Examination Category E-C, the following examination program shall continue in both units:

y. ..

L 1

(1) Visual examinations to assess the general condition of the supression chamber shall be performed on designated suppression chamber surfaces. Specific l evaluation areas will be selected for examination as determined by the responsible engineer, based on previous examination results and recommendations from ABB Impell Report No. 03-0670-1360. Examinations will l.

be focused on those areas having the greatest concentration of deep pits. The examination frequency will be dependent on the diameter and depth of the pits i and will be determined by the responsible engineer. The next examinations are I

currently planned for 2003 (Unit 3 refueling outage 3R14) and 2004 (Unit 2 refueling outage 2R15), I l  !

(2) In conjunction with the visual examination of the evaluation areas, pit depth l measurements shall be taken from the interior of the suppression chamber.

These measurements will be used to evaluate the acceptability of the pits, as well as to determine pit depth growth rates. The frequency will be determined by

. the responsible engineer.

l (3) Ultrasonic thickness measurements shall be taken on designated evaluation  !

areas in four bays, from the outside of the suppression chamber. These l measurements will be performed every third cycle, nominally every 6 years. l (4) The evaluations of pitting will be conducted using the methodology and l

[ acceptance criteria provided in ABB Impell Rcport No. 03-0670-1360. The depth readings taken on the evaluation areas will be used to update and refine the  ;

pitting corrosion rate. i l

(5) A VT-3 examination shall be performed on the exterior surface of the l suppression chamber below the horizontal centerline (elev.110 ft.) in I

accordance with Table IWE-2500-1, examination category E-A. The frequency will be every third refuel cycle, nominally 6 years.  ;

l (6) The results of future examinations and evaluations shall be documented in the PECO records system.

2.11,.5 Staff Evaluation of CRR-11 In lieu of meeting the requirements of ASME Section XI,1992 Edition through 1992 Addenda, Paragraph IWE-2500(c) and Table IWE-2500-1, Examination Category E-C, " Containment  !

Surfaces Requiring Augmented Examination," that require surfaces identified by IWE-1240 to be visually examined from both sides when accessible, or examined for wall thinning using an l ultrasonic thickness measurement method when only one side of the wall is accessible, the licensee proposed to use its own examination program to demonstrate the integrity of the suppression chamber on both units.

Based on previous examination results, improvement of water chemistry treatment, and evaluation of examination results, the licensee developed an examination program for suppression chamber examinations. The performance of this program starts with a general inspection of the interior surfaces of the suppression chamber. From the results of general examinations, specific evaluation areas will be determined and the degradation cf containment i

o , )

• l i

1 f

surfaces (including degraded coating, corrosion pits, etc.) will be evaluated. Also, in conjunction with the underwater examinations, ultrasonic thickness measurements will be, periodically, taken on the defined evaluation areas from the outside of the suppression chamber and from the inside of the suppression chamber at the pitted areas. In addition, a VT-3

~

examination shall be performed on the exterior surface of the suppression chamber below the horizontal centerline (elev.110 ft.) in accordance with Table IWE-2500-1, examination category E-A. The final results will be evaluated and documented.

On the basis discussed above, the staff finds that the implementation requirements of this program provide a reasonable method to examine containment surfaces requiring augmented examination. Therefore, the staff concludes that the alternative proposed by the licensee provides an acceptable level of quality and safety, and is authorized pursuant to 10 CFR 50.55a(a)(3)(i).

3.0 CONCLUSION

The staff concludes that for Propo. sed Alternatives CRR-03,05,08,09,10, and 11, the licensee's 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 Proposed Alternatives CRR-01,02,04,06, and 07, the staff concludes that compliance with the ASME Code requirements would result in hardship without a compensating increase in the level of quality and safety, and that PECO Energy's 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).

Principal Contributor: T. Cheng l

Date: September-17, 1999 i

s

~

r-

.j- .-

• +  :,..*

t l' ',- 4.0 REFERENCE,3

-(1) Letter, Garrett D. Edwards, PECO to NRC," Submittal of Proposed Alternatives to the Requirements of 10 CFR 50.55a(g)(ii)(B)(1) Concerning the Conthinment inservice l

Inspection Program, Peach Bottom Atomic Power Station, Units 2 and 3," dated February 17,1999

, (2) Letter, James A. Hutton, PECO to NRC, " Submittal of Proposed Alternatives to the Requirements of 10 CFR 50.55a(g)(6)(ii)(B)(1) Concerning the Containment inservice Inspection Program, Peach Bottom Atomic Power Station, Units 2 and 3," dated

' August 11,'1999 l ,

l l

L l

l' I

l l

l l

l l-7;.

L J

h.A September 17, 1999 J. Hutton 2-lf you have any questions regarding this matter, please contact the Peach Bottom Project Manager, Bartholomew C. Buckley, at (301) 415-1483.

Sincerely, Original signed by:

James W. Clifford, Chief, Section 2 Project Directorate i Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-277 and 50-278

Enclosure:

Safety Evaluation cc w/ encl: See next page DISTRIBUTION:

ESeekst4WD11 PUBLIC PDI-2 r/f EAdensam (e-mail)

JClifford MO'Brien BBuckley E. Imbro l DTerao  !

RScholl (e-mail RFS)

OGC ]

GHill(4)

ACRS MTschiltz, EDO (R-l)

MOprendek, RGN l DOCUMENT NAME:G:\PDl-2\PeachBottom\ RELA 4973.wpd j

• See previous concurrence l OFFICE PDl 2/PMTA PDid/db' EMEB OGC, _

PDl/SC NAME BBuckley MO'bIien SE did JClib DATE 09/ @ /99 09/ /99 08/25/99 09/ /3 /99 09// 7 /99 OFFICIAL RECORD COPY l

I i

September 17, 1999 l <.,-*

L J. Hutton l If you have any questions regarding this matter, please contact the Peach Bottom Project Manager, Bartholomew C. Buckley, at (301) 415-1483.

Sincerely, Original signed by:

l James W. Clifford, Chief, Section 2 Project Directorate i

, Division of Licensing Project Management Office of Nuclear Reactor Regulation j

]

i Docket Nos. 50-277 and 50-278 i

l

Enclosure:

Safety Evaluation I l

)

cc w/ encl: See next page l

DISTRIBUTION:

Docket File PUBLIC PDI-2 r/f EAdensam (e-mail)

JClifford MC'Brien BBuckley E. Imbro DTerao RScholl (e-mail RFS) i OGC i GHill(4) l ACRS l

MTschiltz, EDO (R-l) l MOprendek, RGN-l

(. DOCUMENT NAME:G:\PDI-2\PeachBottom\ Rela 4973.wpd j

• See previous concurrence '

OFFICE PDI-2/PM Q'A PDid/Lk

• EMEB OGC, _ PDl/SC  !

NAME BBuckley Mb$rien SE did

~

JClib

'\

DATE 09/ 4 /99 09/ '1 /99 08/25/99 09/ /) /99 09// 7 /99 OFFICIAL RECORD COPY

!