ML20195D016
| ML20195D016 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom, Limerick  |
| Issue date: | 11/11/1998 |
| From: | Geoffrey Edwards PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-98-04, GL-98-4, NUDOCS 9811170273 | |
| Download: ML20195D016 (18) | |
Text
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' Station Cupport Department A 10CFR50.54(f)
< PECO NUCLEAR escoee c - ev 965 Chesterbrook BotAevard A Unit of PECO Energy Wayne, PA 19087-56rt November 11,1998 Docket Nos. 50-277 50-278 50-352 i 50-353 l l
License Nos. DPR-44 DPR-56 NPF-39 NPF-05 U.S. Nuclear Regulatory Commission l
Attn: Document Control Desk Washington, DC 20555-0001 S abject: Limerick Generating Station, Units 1 and 2 Peach Bottom Atomic Power Station, Units 2 and 3 l Response to Generic Letter 98-04, " Potential for Degradation of !
the Emergency Core Cooling System and the Containment Spray l l System After a Loss-of-Coolant Accident Because of Construction I and Protective Coating Deficiencies and Foreign Material in Containment" t u
Dear Sir / Madam:
l l' Attached is PECO Energy's response to NRC Generic Letter (GL) 98-04 " Potential for l
! Degradation of the Emergency Core Cooling System n I the Containment Spray System After a Loss-of-Coolant Accident Because of vonstruction and Protective Coating Deficiencies and Foreign Material in Containment," for Limerick Generating Station (LGS), Unit 1 and 2, and Peach Bottom Atomic Powcr Station (PBAPS), Units 2 and 3.
l On July 14,1998, the NRC issued GL 98-04 to alert licensees that foreign material continues to be found inside operating nuclear power plant containments. During a design basis loss of coolant accident (DB LOCA), this foreign material has the potential to t1ock an Emergency Core Cooling System (ECCS) or safety-related containment spray system (CSS) flow path or damage ECCS or safety-related CSS equipment. In addition, construction deficiencies and problems with material condition of ECCS structures, systems, and components (SSCs) inside containment continue to be identified. Design deficiencies have been discovered which could degrade the ECCS or safety-related CSS. The NRC expects licensees to ensure thet the ECCS and safety-related CSS remain capable of performing their intended safety functions.
This GL was also iscued to alert licensees to problems associated with the material condition of Service Level 1 protective coatings inside the containment. The NRC is requesting information in accordance with 10CFR50.54(f) in order to evaluate licensees' programs for ensuring that Service Level 1 protective coatings inside containment do not detach from their substrate during a DB LOCA and interfere with the operation of the ECCS or safety-related CSS. Specifically, the NRC is requesting that within 120 days of the date of this GL, licensees submit a written response as stipulated in the " Required Information" section of GL 98-04. .
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- Nov;mber 11,1998
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- Accordingly, the attachments to this letter provide PECO Energy's response to GL 98-04. The response for LGS, Units 1 and 2, is contained in Attachment 1. Attachment 2 contains the
- response for PBAPS, Units 2 and 3. Each attachment restates the information required followed
' by our response. This information is being submitted under affirmation, and the required affidavit is enclosed.
If you have any questions or require additional information, please do not hesitate to contact us.
Very truly yours, -
I Garrett D. Edwards Director- Licensing
- Attachments / Enclosure L . cc: H. J. Miller, Administrator, Region I, USNRC (w/ attachments / enclosure) l A. L. Burritt, USNRC Senior Resident inspector, LGS (w/ attachments / enclosure)
A.C. McMurtray, USNRC Senior Resident inspector, PBAPS (w/ attachments / enclosure) )
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ENCLOSURE Affidavit
- _ COMMO,NWEALTH OF PENNSYLVANIA .
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COUNTY OF CHESTER :
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J. J. Hagan, being fit: hly swom, depcses and says:
That he is Vice President of PECO Energy Company; that he has read the foregoing response to NRC Generic Letter 98-04, " Potentia! for Dearadation of the Emergency Core Cooling System and the Containment Spray System After a Loss-of-Coolant Accident Because of Construction and Protective Coating Deficiencies and Foreign Material in Containment," for Limerick Generating Station, Units 1 and 2, and Peach Bottom Atomic Power Station, Units 2 and 3, and knows the contents thereof; and that the l statements and matters set ' orth therein are true and correct to the best of his knowledge, information, and belief.
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! before me this /# day o 1 b i1998. t i
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Notary Public 4
NOTARIAL SEAL CAROL A. WALTON. Notary Put95 City of Philade6phia. Phde. Courwy My Cosessinston Expires May 28. 2001 d
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ATTACHMENT 1 Limerick Generating Station Units 1 and 2 Response to Generic Letter 98-04 l
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Docket Nos. 50-352/50-353 Attachment i November 11,1998 Page 1 of 6
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Limerick Generating Station Units 1 and 2 Resoonse to Generic Letter 98-04 l
i l Reauired Information ltem 1 A summary description of the plant-spacific program orprograms implemenled to ensure that Service Level 1 protective coatings usac inside the containment are procured, applied, and maintained in compliance with applicable regulatory requirements and the plant-specific licensing j basis for the facility. Include a discussion of how the plant-specific program meets the applicable criteria of 10 CFR Part 50, Appendix B, as well as information regarding any applicable standards, plant-specific procedures, or other guidance used for: (a) controlling the procurement of coatings and paints used at the facility, (b) the qualification testing ofprotective coatings, and (c) surface preparation, application, surveillance, and maintenance activities forprotective coatings.
Maintenance activities involve reworking degraded coatings, removing degraded coatings to sound coatings, correcyy preparing the surfaces, applying new coatings, and verifying the quality of the coatings.
Response
PECO Energy has implemented controls for the procurement, application, and maintenance of Service Level 1 protective coatings used inside the containment in a manner that is consistent with the licensing basis and regulatory requirements applicable to Limerick Generating Station
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(LGS). The requirements of 10 CFR 50, Appendix B, are implemented through specification of appropriate technical and quality requirements for the Service Level 1 coatings program which includes ongoing maintenance activities.
For LGS, Service Level 1 coatings are subject to the requirements of the PECO Energy coatings program procedure. This procedure provides the design and process controls (or cross-references other PECO Energy procedures for design and process controls) for procurement, qualification testing, surface preparation, application, inspection, surveillance, and maintenance of Service Level 1 coatings.
PECO Energy follows ASTM D3843-93 to fulfill 10 CFR 50, Appendix B. requirements with l clarification, exception, and one additional requirement as stated in LGS UFSAR Section 17.2.ll.g.
l This ASTM standard was implemented as a replacement for ANSI N101.4-1972 with no reduction in level of commitment to Regulatory Guide 1.54. Service Level 1 coatings formulated before i
issuance of replacement ASTM standards are subject to ANSI N101.2-1972 and ANSI N5.9-1967 (Revised as ANSI N512-1974). Assurance that the applicable requirements for the procurement, application, inspection, and maintenance are implemented, is provided by procedures and programmatic controls, under the LGS Quality Assurance Program describee in LGS UFSAR Section 17.2. PECO Energy recognizes that the NRC is drafting a replacement to Regulatory Guide 1.54 which is based on replacement ASTM standards. PECO Energy intends to review such guidance after issuance and re-evaluate current commitments as appropriate.
PECO Energy is evaluating the guidance provided in EPRI TR-109937 " Guideline on Nuclear
{ Safety-Related Coatings." Improvements to our existing procedures for Service Level 1 coatings will be implemanted upon completion of the evaluation, as appropriate. This evaluation is intended to be completed by March 31,1999, i
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Docket Nos. 50-352/50-353 Attachnyt 1 Novemb:r 11,1998 Page 2 of 6 l
(a) Service Level i coatings used for new applications or repair / replacement etivities are procured from vendors with a quality assurence program meeting the applicable requirements of 10 CFR 50, Appendix 8. Vendors are required to meet applicable technical and quality requirements specified by PECO Energy in procurement documents. Acceptance activities (e.g., receipt inspection, source surveillance, etc.) are conducted in accordance with procedures which are consistent with requirements of the LGS QA Program described in LGS UFSAR Section 17.2, and with LGS commitments to regulatory guides and industry standards as stated in LGS UFSAR Section 17.2.ll. This specification of required technical and quality l requirements combined with appropriate acceptance activities provides assurance that the i
coatings received meet the requirements of the procurement documents.
(b) Except for relatively smell amounts of unqualified coatings (estimated as less than 1% of all containment coatings) applied by vendors on supplied components (where it was impractical to implement the Service Level 1 coatings program on the vendor or to replace the coatings in the field with a qualified coating), the qualification testing of Service Level 1 qualified coatings used for new applications or repair / replacement activities inside containment meets the applicable requirements contained in the standards and regulatory commitments referenced above. These coatings have been evaluated to meet the applicable standards and regulatory requirements previously referenced. Also, any substitute coatings used in combination with original coatings are evaluated as qualified coating " systems" to meet the same standards and regulatory requirements.
Additions of unqualified coat lngs (including significantly degraded qualified coatings not i removed / repaired / replaced) are required by the PECO Energy Maintenance Rule implementation procedure to be tracked in a calculation (an unqualified coatings inventory).
Additions are required to be limited by the licensing basis for the LGS replacement suction j strainers, as described in response to (2)(i)(b) below, implementation of this activity will occur after the first expanded coating condition assessment for each unit (dates specified in l response to (2)(i)(a) below).
(c) The surface preparation, application and inspection of Service Level 1 coatings used for new applications or repair / replacement activities inside containment meet the applicable portions of the standards and regulatory commitments referenced above. Documentation of completion of these activities is performed consistent with the applicable requirements.
l However, where the requirements of the standards and regulatory commitments did not I
address or were not applicable to repair / replacement activities, the activities were performed in a manner consistent with the generally accepted practices for coatings repair / replacement.
These practices are described in various ASTM standards and coating practice guidelines by industry organizations issued concurrent to those to which PECO sinergy has a commitment.
l PECO Energy recognizes that the NRC has not formally endorsed many of the more recent ASTM standards or industry guidelines, but nonetheless, they provide useful information which can be appropriately applied to provide assurance that repair / replacement activities on i Service Level 1 coatings are effective in maintaining the acceptability of the coatings.
l PECO Energy presently performs visual examinations of the accessitWe drywell and Suppression Pool surfaces as part of the surveillance test program and the Primary Containment Leakage Rate Testing Program. In addition, PECO Energy presently performs inspections of the immersed surfaces of the Suppression Pool, as a self-initiated program. Currently, these examinations and inspections are performed once per refueling outage, every 2 years per unit.
l Dock:t Nos. 50-352/50-353 Attachmint i Nov:mbir 11,1998 Page 3 of 6 As an improver.1ent to the coatings condition monitoring program, containment coatings are included in the Maintenance Rule scope for LGS, and coating condition assessments will be conducted in accordance with the PECO Energy Maintenance Rule implementation procedure.
Assessments will be performed during refueling outage periods, with assessment frequencies for specific appiications to be determined after review of the EPRI coatings guideline, as previously noted, and other relevant factors, including implementation of Subsection IWE of ASME Section XI. As localized areas of signifcantly degraded qualified coatings are identified, those areas are i
required to be evaluated as non-conforming conditions, and either are determined to acceptable, or are scheduled for removal, repair, or replacement, as necessary. The acceptability of indeterminate coatings, inaccessible coatings, and degraded unqualified coatings also is required to be determined as part of the periodic coating condition assessments.
The periodic condition assessments and required maintenance activities assures that the amount of coatings which may be susceptible to detachment from their substrates during a LOCA event is managed.
Reauired information -! tem 2 Information demonstrating compliance with item (i) or item (ii):
l 1. Forplants with licensing-basis requirements for tracking the amount of unqualified l coatings inside the containment and for assessing the impact ofpotential coating debris on
\ the operation of safety-related SSCs during a postulated design basis LOCA, the following 1
information shall be provided to demonstrate compliance:
a) The date and findings of the last assessment of coatings, and the planned date of the next assessment of coatings.
Response
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l Note: LGS UFSAR Section 6.1.2 provides a discussion which accounts for the amount of l unqualified coatings inside containment and for assessing the impact of potential coating debris I on the operation of safety-related SSCs during a postulated DB LOCA. Therefore, item (2)(i)is considered applicable.
I As previously stated in response to (1) above, visual examinations and inspections of primary containment surfaces have been performed at LGS during previous refueling outages. The dates of the lates; examinations are April,1997 for Unit 2, and April,1998 for Unit 1. Results of these examinations are ns follows. Unit 1 and Unit 2 internal drywell pressure boundary surfaces (coated with a modified epoxy phenolic) were satisfactory with no deficiencies noted. In the vapor phase of the Unit 1 and Unit 2 Suppression Pools (coated with inorganic zine), localized areas of rusting and resulting rust streaks (at cut-outs in Q-decking and sheet metal skin subjected to humid conditions), areas of pinpointed rust (on conduit hangers, catwalk support pads, on 30
( 70% of diaphragm slab O-decking), and isolated ares of mechanical damage were noted, but i
overall coating condition (includir g downcomers and reactor pedestal sidewalh) was described as good. Rust scales were small and no large chips, flaking or delamination of coatings was identified. Corrosion indications on Unit 1 were more progressed than on Unit 2. These indications were noted on previous inspections and had not progressed enough to warrant action.
- in the immersion phase of the Unit 1 and Unit 2 Suppression Pools (coated with inorganic zinc),
the cocting has remained intact. Localized corrosion cells with associated nodulation and pitting i
Dock:t Nos. 50-352/50-353 Attachm nt i Nov:mbir 11,1998 Page 4 of 6 corrosion were noted in varying degrees of dispersion density. Tiger striping was identified on approximately 20% of the wall panels with increased frequency at the floor e!evation and extending upwards approximately 3 feet. Numerous floor areas showed mechanical damage to the coatings (nicks, scrapes, etc.) and 10%-30% coating depletion. Identified indications and discrepancies were dispositioned by engirieering evaluations as acceptable. Examinations and inspections of comparable scope are scheduled to be performed in April,1999 for LGS, Unit 2.
The scheduled date for expanded coating condition assessments at LGS are April,2000 for Unit 1 and April,2001 for Unit 2. The scope of these coating assessments willinclude not only examination of exposed internal surfaces of primary containment pressure boundary, but also examination of exposed surfaces of systems, structures, and components within containment.
Eva!uation requirements contained in the Maintenance Rule implementation procedure will be used to disposition examination results.
b) The limit for the amount of unqualified protective coatings allowed in the containment and how this limit is determined. Discuss any conservatism in the method used to detem1ine this limit.
Response
LGS has no explicit limit on unqualified coatings for either unit in its licensing basis. The quantity of unqualified coatings was identified during initial plant licensing, was evaluated for its impact on the performance of Residual Heat Removal (RHR) and Core Spray (CS) systems, and was found to be acceptable. It follows that additions (or subtractions) of unqualified coatings would be accounted for, and the conclusion on the impact of quantity of unqualified coatings on the performance of RHR and CS systems would be verified. PECO Energy plans to update the UFSAR, as appropriate, to refer to use of administrative controls to track unqualified coatings and to ensure that the licensing basis limits for debris are not exceeded. Consistent with applicable regulatory requirements, the type and quantity of debris were not explicitly considered when the original calculations for the ECCS strainer head loss were performed.
In response to NRC Bulletin 96-03, large passive replacement ECCS suction strainers have recently been installed in LGS Unit 1, and will be installed in LGS Unit 2 in April,1999.
Consequently, the following discussion addresses the anticipated licensing basis pending resolution of NRC Bulletin 96-03.
l The design input to the ECCS strainer calculations for the amount of unqualified coatings, qualified coatings in steam / water jet zone of influence, and degraded qualified coatings in the containment (as identified from periodic visual inspections) is documented in the ECCS strdner hydraulic calculations. Therefore, the amount of these coating materials must be managed, in addition to the quantity of fibrous, particulate, and other miscellaneous debris, to assure that the l analyzed functional capability of the ECCS is not compromised.
The new ECCS pump suction strainers are designed to perform satisfactorily in the presence of 100% of the containment coatings which are installed in the LOCA pipe break steam / water jet zone of influence. This amount of coating debris is determined in accordance with the methodology documented in the BWR Owners' Group Utility Resolution Guidanca (URG)
Docket Nos. 50-352/50-353 Attachment 1 NovEmbsr 11,1998 Page 5 of 6 I
document (NEDO-326*9, Section 3.2.2.2.2.1.1. The conservative methodology used to establish I the amount of coating nebris has been found acceptable by the NRC for LGS Unit 1, as documented in Amendment No.128 to Facility Operating License No. NPF-39, dated May 14, 1998. This response assumes that Unit 2 methodology will be similarly accepted in a pending license amendment.
Generic estimates provided in the URG of 47 pounds for inorganic zinc,150 pounds for dust / dirt, and 50 pounds for rust chips from unpainted structures, were used to size the strainers.
Unqualified coatings (listed in LGS UFSAR, Table 6.1-6, as 26 pounds) and indeterminate coatings were conservatively accounted for by artificially increasing the quantity of particulate debris used to size the strainer by 1000 pounds. The new licensing basis also includes 900 cubic feet of insulation and an additional strainer head loss equivalent to an additional 1000 pounds of sludge. The SER noted that Method 2 of the URG was used, which was considered conservative for break selection, reasonable for debris generation, and consistent with the guidance in Regulatory Guide 1.82, Revision 2. A conservative factor of 1.0 was used for transport o' debris from the drywell and within the suppression pool to the surface of the strainers.
Amounts of unqualified coatings (including significantly degraded qualified contings not removed / repaired / replaced) are required to be maintained below the above stated limits, through use of administrative controls, as previously stated.
The results of BWR Owners' Group LOCA testing of coupons representing unqualified coating systems provide compelling evidence that failure of typical unqualified coating systems which pass a visual inspection is highly unlikely in the first 30 minutes of the LOCA. Only for the first 2 to 15 minutes of the LOCA event, depending upon the pipe break size, are suppression pool turbulence levels adequate to maintain coating debris in sc.g 'sion in the pool where it would be available for accumulation on the ECCS strainers. Since the coating debris will quickly settle to the bottom of the suppression pool after the turbulence subsides,little,if any, of the coating debris (if eventually released sometime after the first 30 minutes of the LOCA) would be available to accumulate on the strainers. In sizing the replacement ECCS strainera 'or LGS, no credit was taken for the delayed release of coating debris; therefore, these designs are conservative with respect to the limit on this coating debris source.
PECO Energy is participating in the BWR Owners' Group Containment Coatings Committee.
Activities in progress are expected to result in justifying less conservative assumptions for coating debris release and transport, which would raise limits on acceptable quantities of unqualified coatings and degraded qualified coatings without challenging strainer functional capability, c) If a ccmmercial-grade dedication program is being used at your facility for dedicating commercial-grade coatings for Service Level 1 applications inside the containment, discuss how the program adequately qualifies such a coating for Service Level 1 service.
Identify which standards or other guidance are currently being used to dedicate containment coatings at your facility.
Response
PECO Energy does NOT currently employ commercial grade dedicatien for Service Level 1
! coatings used indde containment at Limerick Generating Station. This response applies to l
Service Level i coatings used inside containment that are procured, applied, and maintained by i
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PECO Energy or its on-site coatings application agency, under the LGS QA Program. This response does not address the relatively small amount of qualified coatings applied by vendors under their own 10CFR50 Appendix B programs.
it. Forplants with M the above licensing-basis requirements, information shall be provided to demonstrate compliance with the requirements of 10CFRSO.46b(5), 'Long-term cooling" and the functional capability of the safety-related CSS as set forth in yourlicensing basis. If a licensee can demonstrate this compliance without quantifying the amount of unqualified coatings, this is acceptable.
Respor.se l This item is not applicable to LGS, Units 1 and 2.
a) The following information shall be provided:If commercial-grade coatings are being used L at your facility for Service Level 1 applications, and such coatings are not dedicated or controIIed under your Appendix B Quality Assurance Program, provide the regulatcry and safety basis for not controlling these coatings in accordance with such a program Additionally, explain why the facility's licensing basis does not require such a program.
Response
See response to (2)(i)(c) above.
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' i ATTACHMENT 2 l=
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Response to Generic Letter 98 !
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Docktt Nos. 50-277/50-278 Attachment 2 Novemb:r 11,1998 Page 1 of 6 I -
Peach Bottom Atomic Power Station Units 2 and 3 Response to Generic Letter 98-04 Reaulted Information - Item 1 A summary description of the plant-specific program or p:ograms implemented to ensure that Service Level 1 protective coatings used inside the containment are procured, applied, and maintained in compliance with applicable regulatory requirements and the plant-specific iicensing basis for the facility. Include a discussion of how the picnt-specific program meets the applicable criteria of 10 CFR Part 50. Appendix B, as well as information regarding any applicable standards, plant-specific procedures, or other guidance used for: (a) controlling the procurement of coatings and paints used at the facility, (b) the qualification testing ofprotecdve coatings, and (c) surface preparation, application, survei!Iance, and maintenance activities forprotective coatings.
Maintenance activities involve reworking degraded coatings, removing degraded coatings to sound coatings, correctly preparing the surfaces, applying new coatings, and verifying the quality of the coatings.
Resconse PECO Energy has implemented controls for the procurement, application, and maintenance of Service Level 1 protective coatings used inside the containment in a manner that is consistent with the licensing basis and reguletory requirements applicable to Peach Bottom Atomic Power Station (PBAPS). The requirements of 10 CFR 50, Appendix B, are implemented through l specification of appropriate technical and quality requirements for the Service Level 1 coatings program which includes ongoing maintenance activities.
For PBAPS, Service Level 1 coatings are subject to the requirements of the PECO Energy coatings program procedure. This procedure provides the design and process cor.trols (or cross-references other PECO Energy procedures for design and process controls) for procurement, qualification testing, surface preparation, application, inspection, surveillanco, and maintenance of Service Level 1 coatings.
PECO Energy follows ASTM D3843-93 to fulfill 10 CFR 50 Appendix B requirements with clarification, exception, and one additional requirement as stated in PBAPS UFSAR Section D.11, Appendix 17.2A.8. This ASTM standard was implemented as a replacement for ANSI N101.4-j 1972 with no reduction in level of commitment to Regulatory Guide 1.54. Service Level 1 coatings femulated before issuance of replacement ASTM standards are subject to ANSI N101.2-1972 and ANSI N5.9-1967 (Revised as ANSI N512-1974). Assurance that the applicable requirements for the procurement, application, inspection, and maintenance are implemented, is provided by procedures and prograramatic controls, under the PBAPS Quality Assurance program described in PBAPS UFSAR Section D.11. PECO Energy recognizes that the NRC is drafting a replacement to Regulatory Guide 1.54 which is based on replacement ASTM standards. PECO Energy intends to review such guidance after issuance and re-evaluate currer.t commitments as appropriate.
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PECO Energy is evaluating the guidance provided in EPRI TR-109937 " Guideline on Nuclear Safety-Related Coatings." improvements to our existing procedures for Service Level 1 coatings will be implemented upon completion of the evaluation, as appropriate. This evaluation is intended to be completed by March 31,1999.
Dock t Nos. 50-277/50-278 Attachment 2 Novembtr 11,1998 Page 2 of 6 l l
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(a) Service Level 1 coatings used for new applications or repair / replacement activities are procured from vendors with a quality assurance program meeting the applicable requirements of 10 CFR 50, Appendix B. Vendors are required to meet applicable technical and quality requirements specified by PECO Energy in procurement documents. Acceptance activities (e.g., receipt inspection, source surveillance, etc.) are conducted in accordance with procedures consistent with the PBAPS QA Program as described in PBAPS UFSAR Section D.11, and with PBAPS commitments to regulatory guides and industry standards as stated in PBAPS UFSAR Section D.11, Appendix 17.2A. This specification of required technical and quality requirements combined with appropriate acceptance activities provides assurance that the coatings received rneet the requirements of the procurement documents.
(b) Except for relatively small amounts of unqualified coatings (estimated at less that 1% of all containment coatings) applied by vendors on supplied componerits (where it was impractical to implement the Service Level 1 coatings program on the vendor, or to replace the coatings in the field with a qualified coating), the qualification testing of Service Level 1 qualified coatings used for new applications or repair / replacement activities inside containment meets the applicable requirements contained in the standards and regulatory comraitments referenced above. These coatings have been evaluated to meet the applicable standards and regulatory requirements previously referenced. Also, any substitute coatings used in combination with original coatings are evaluated as qualified coating " systems" to meet the same standards and regulatory requirements.
Additions of unqualified coatings (including significantly degraded qualified coatings not removed / repaired / replaced) are required by the PECO Energy Maintenance Rule implementation procedure to be tracked in a calculation (an unqualified coatings inventory).
Additions are required to be limited by the anticipated licensing basis for the PBAPS replacement ECCS suction strainers, as described in response tc (2)(ii) below.
Implementation of this activity will occur after the first expanded coating condition assessment for each unit (dates specified in response to (c) below).
(c) The surface preparation, application and inspection of Service Level 1 coatings used for new applications or repair / replacement activities inside containment meet the applicable portions
- of the standards and regulatory commitments referenced above. Documentation of l completion of these activities is performed consistent with the applicable requirements.
l However, where the requirements of the sta dards and regulatory commitments do not j address, or are not applicable to repair / replacement activities, the activities are performed in a l manner consistent with the generally accepted practices for coatings repair / replacement.
These practices are described in various ASTM standards and coating practice guidelines by industry organizations issued subsequent to those to which PECO Energy has a commitment.
PECO Energy recognizes that the NRC has not formally endorsed many of the more recent ASTM standards or industry guidelines, but nonetheless, they provide useful information which can be appropriately applied to provide assurance that repair / replacement activities on Service Level 1 coatings are effective in maintaining the acceptability of the coatings.
i PECO Energy presently performs visual examinations of the accessible drywell and torus surfaces as part of the surveillance test program and the Primarf Containment Leakage Rate Testing Progrem. Currently, these examinations are performed once pu refueling outage, every
, 2 years per unit. Results of the last examination for both units are as follows. In general, drywell interior pressure boundary surfaces (coated with inorganic zinc primer and epoxy topcoat) have isolated areas of light rust and chipped paint, but no cracking, peeling, or delamination of the 4
Docket Nos. 50-277/50-278 Attachment 2 November 11,1998 Page 3 of 6 l
coating. Torus surfaces above the waterline (coated with inorganic zinc primer and epoxy topcoat on Unit 2, and inorganic zinc only on Unit 3) have isolated patches of light rust and (in Unit 2 only) peeling paint, but no cracking, widespread peeling, or delamination of the coating.
l In addition, PECO Energy presently performs inspections of immersed torus surfaces during refueling outages, as a self-initiated program. Results of the last examination fcr both units are as follows. In general, immersed torus surface coating (coated with inorganic zinc and repaired in localized areas with underwater epoxy) has remained intact with localized corrosion cells and associated nodulation and pitting corrosion present in varying degrees of dispersion density.
Tiger striping is present on approximately 40% of the immersion area with increased frequency at the upper section Numerous areas of mechanical damage to the coatings (nicks, scrapes, etc.)
with substrate corrosion exist.
l Indications and discrepancies identified in examinations and inspections were dispositioned by l engineering evaluations as acceptable.
As an improvement to the coatings condition monitoring program, primary containment coatings are included in the Maintenance Rule scope for PBAPS, and coating condition assessments will be conducted in accordance with the PECO Nuclear Maintenance Rule implementation procedure. Assessments will be performed during refueling outage periods, with assessment frequencies for specific applications to be determined after review of the EPRI coatings guideline, as previously noted, and other relevant factors, including implementation of Subsection IWE of i ASME Section XI. As localized areas of significantly degraded qualified coatings are ident;iied, I those areas are required to be evaluated as non-conforming conditions, and either are determined to be acceptable, or are scheduled for removal, repair, or replacement, as necessary. The acceptability of indeterminate coatings, inaccessible coatings, degraded unqualified coatings, and existing coatings applied before PBAPS operational phase commitment to Regulatory Guide 1.54, also is required to be determined as part of the periodic coating conditio ssessments.
The scheduled dates for expanded coating condition assessments at PBAPS are October,1999 for Unit 3, and October,2000 for Unit 2. The scope of these coating assessments will include not only examination of exposed internal surfaces of primary containment pressure boundary, but also examination of exposed surfaces of systems, structures, and components within primary containment. Evaluation requirerrents contained in the Maintenance Rule implementation procedure will be used to dispo' .an examination results.
l The periodic condition assessments and required maintenance activities assures that the amount of coatings which may be susceptible to detachment from their substrates during a LOCA event is managed.
Reauired Information Item 2 Infom1ation demonstrating compliance with item (i) or Item (ii):
(i) For plants with licensing-basis requirements for tracking the amount of unqualified coatings inside the containment and for assessing the impact of potential coating debris on the operation of safety-related SSCs during a postulated design basis LOCA, the following l information shall be provided to c'emonstrate compliance: 1 (a) The date and findings of the last assessment of coatings, and the planned date of the next assessment of coatings.
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Docket Nos. 50-277/50-278 Attachment 2 Novsmb r 11,1998 Page 4 of 6 l
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Response l N/A Note: PBAPS licensing basis does not include requirements for tracking the amount of unqualified coatings inside the containment, nor does the licensing basis include requirements for assessing the impact of potential coating debris on the operation of safety-related SSCs during a postulated DB LOCA. Therefore, response to item (2)(ii) is provided.
(b) The ilmit for the amount of unqualified protective coatings allowed in the containment and how this limit is determined. Discuss any conservatism in the method used to determine this limit. l l
Response I N/A - see note above (c) If a commercial-grade dedication program is being used at your facility for dedicating commercial-grade coatings for Service Level 1 applications inside the containment, discuss how the program adequately qualifies such a coating for Service Level 1 service.
i Identify which standards or other guidance are currently being used to dedicate containment coatings at your facility.
I Response l
N/A - see note above
! (ll) For plants without the above licensing-basis requirements, information shall be provided to l demonstrate compliance with the requirert.ents of 10CFR50.46b(5), 'Long-term cooling
- l and the functional capability of the safety-related CSS as set forth in yourlicensing basis.
If a licensea can demonstrate this compliance without quantifying the amount of unqualified coatings, this is acceptable.
Response
In response to NRC Bulletin 96-03, large passive replacement ECCS suction strainers l .
have been installed recently at Units 2 and 3 of PBAPS. Consequently, the following l diccussion addresses the anticipated licensing basis pending resolution of NRC Bulletin 1
96-03.
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The design input to the ECCS strainer calculations for the amount of unqualified coatings,
, the containment (as identified from periodic visual inspections) is documented in the ECCS strainer hydraulic calculations. Therefore, the amount of these coating materials
- must be managed, in addition to the quantity of fibrous, particulate, and other miscellaneous debris, to assure that the analyzed functional capability of the ECCS is not i compromised.
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Docket Nos. 50-277/50-278 Attachment 2 Novcmbrr 11,1998 Page 5 of 6 The new ECCS pump suction strainers are designed to perform satisfactorily in the presence of 100% of the containment coatings which are installed in the LOCA pipe break steam / water jet zone of influence. This amount of coating debris is determined in accordance with the methodology documented in the BWR Owners' Group Utility Resolution Guidance (URG) document (NEDO-32686), Section 3.2.2.2.2.1.1. The conservative methodology used to establish the amount of coating debris has been accepted by the NRC for Limerick Generating Station, Unit 1, as documented in Amendment No.128 to Facility Operating License No. NPF-39. Since PBAPS methodology is identical to LGS, this response assumes that PBAPS, Units 2 and 3, methodology will be similarly accepted in pending license amendments.
Generic estimates of 47 pounds for inorganic zinc,150 pounds for dust / dirt, and 50 pounds for rust chips from unpainted structures, as provided by the URG, were used to size the strainers.
Unqualified coatings (assumed as 26 pounds) and indeterminate coatings were conservatively accounted for by artificially increasing the quantity of particulate debris used to size the strainer by 1000 pounds. The new licensing basis also includes 700 cubic feet of insulation, and an additional strainer head loss equivalent to an additional 1000 pcunds of sludge. Method 2 of the URG was used, considered conservative for break selection, reasonable for debris generation, and consistent with the guidance in Regulatory Guide 1.82, Revision 2. A conservative factor of 1.0 was used for transport of debris from the drywell and within the suppression pool to the surface of the strainers.
Amounts of unqualified coatings (including significantly degraded qualified coatings not l removed / repaired / replaced) are required to be maintained below the above stated limits, through the use of administrative controls, as previously stated in response to (1)(b).
l The results of BWR Owners' Group LOCA testing of coupons representing unqualified coating systems provide compelling evidence that failure of typical unqualified coating systems which pass a visual inspection is highly unlikely in the first 30 minutes of the LOCA. Only for the first 2 to 15 minutes of the LOCA event, depending upon the pipe break size, are suppression pool turbulence levels adequate to maintain coating debris in suspension in the pool where it would be available for accumulation on the ECCS strainers. Since the coating debris will quickly settle to l the bottom of the suppression pool after the turbulence subsides,little,if any, of the coating debris (if eventually released sometime after the first 30 minutes of the LOCA) would be availablo to j accumulate on the strainers. In sizing the replacement ECCS strainers for PBAPS, no credit was taken for the delayed release of coating debris; therefore, these designs are conservative with respect to the limit oi this coating debris source.
PECO Energy is participating in the BWR Owners' Group Containment Coatings Committee.
Activities in progress are expected to result in justifying less conservative assumptions for coating
, debris generation and transport, which would raise limits on acceptable quantities of unqualified i
coatings and degraded qualified coatings without challenging strainer functional capability.
(a) The following information shall be provided: If commercial-grade coatings are being used at your facility for Service Level f applications, and such coatings are not dedicated or controlled under your Appendix B Quality Assurance Program, provide the regulatory and safety basis for not controlling these coatings in accordance with such a program.
Additionally, explain why the facility's licensing basis does not require such a program.
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l Dock:t Nos. 50-277/50-278 Attachmtnt 2 Nov:mber 11,1998 Page 6 of 6 l
Response
PECO Energy does not currently employ commerciai grade dedication for Service Level 1 coatings used inside containment at PBAPS. This respons) applies to Service Level 1 coatings
! used inside containment that are procured, applied, and maintained by PECO Energy or its on-site coatings application agency, under the PBAPS QA Program. This response does not address the relatively small amount of qualified coatings applied by vendors under their own 10CFR50, Appendix B, programs.
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