ML20195C963

Forwards 120-day Response to NRC GL 98-04, Potential for Degradation of ECCS & CSS After LOCA Because of Construction & Protective Coating Deficiencies & Foreign Matl in Containment

ML20195C963
Person / Time
Site:	Monticello
Issue date:	11/11/1998
From:	Hammer M NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-98-04, GL-98-4, NUDOCS 9811170258
Download: ML20195C963 (9)

Text

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Northern States Power Company l

• • Monticello Nuclear Generating Hant 2807 West County Road 75 Monticello, MN 55362 1

November 11,1998 Generic Letter 98-04 United States Nuclear Regulatory Commission I- Attention: Document Control Desk Washington DC 20555-0001 MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No, DPR-22 Response to Generic Letter 98-04:

Potential for Degradation 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 On July 14,1998, the Nuclear Regulatory Commission issued Generic Letter 98-04 that addressed issues having generic implications regarding the impact of potential coating debris on the operation of safety related systems, structures, and components (SSC) during a postulated design basis LOCA. Protective coatings are necessary inside containment to control radioactive contamination and to protect surfaces from erosion and corrosion. Detachment of the coatings from the substrate may make the ECCS unable to satisfy the requirement of 10 CFR 50.46(b)(5) to provide long-term cooling and containment spray functions following a LOCA. Generic Letter 98-04 requests information under 10 CFR 50.54(f) to evaluate the addressees' programs for ensuring that Senrice Level 1 protective coatings inside containment do not detach from their substrate during a design basis LOCA and interfere with the operation of the ECCS. The NRC intends to use this information to assess whether current regulcory requirements are being correctly implemented and whether these requirements need to bc revised.

The generic letter requires, within 120 days, that licensees provide the information outlined below for each of their facilities:

J (1) A summary description of the plant-specific program or programs implemented to ensure that Service Level 1 protective coatings used inside the containment are O)i

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procured, applied, and maintained in compliance with applicable regulatory

. requitements and the plant-specific licensing 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 infonnation 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 of protective coatings, and (c) surface preparation, application, surveillance, and l

maimenance activities for protective coatings. Maintenance activities involve reworking degraded coatings, removing degraded coatings to sound coatings, l correctly preparing the surfaces, applying new coatings, and verifying the quality of I the coatings.

(2) Information demonstrating compliance with item (i) or item (ii):

l l (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 infonnation 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.

(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 determine this limit.

(c) If a commercial-grade dedication program is being used at your facility l 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 I service. Identify which standards or other guidance are currently being used to dedicate containment coatings at your facility; or, (ii) For plants without the above licensing-basis requirements, information shall be provided to demonstrate compliance with the requirements of 10 CFR 50.46(b)(5), Long-term cooling" and the functional capability of the safety-related CSS as set forth in your licensing basis. If a licensee can demonstrate l this compliance without quantifying the amount of unqualified coatings, this is acceptable. The following information shall be provided:

(a) If commercial-grade coatings are being used at your facility for Service Level 1 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 Page 2 0f 3

i accordance with such a program. Additionally, explain why the facility's licensing basis does not require such a program.

By this letter, Nonhern States Power Company is providing the required 120-day response for the Monticello Nuclear Generating Plant.

, This submittal does not contain any new NRC commitments and does not modify any prior -

l commitments. Please contact Sam Shirey at (612) 295-1449 if you require funher information -

[ related to this request.

Michael F. IIammer MN l

l . Plant Manager l Monticello Nuclear Generating Plant

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Regional Administrator-III, NRC c:

NR.R Project Manager, NRC Resident Inspector, NRC

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State of Minnesota

. Attn: Kris Sanda

! Jay Silberg, Esq.

Attachments

' Affidavit to the US Nuclear Regulatory Commission I Generic Letter 98-04 Requested Information l

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UNITED STATES NUCLEAR REGULATORY COMMISSION l

NORTHERN STATES POWER COMPANY

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MONTICELLO NUCLEAR GENERATING PLANT DOCKET NO. 50-263 RESPONSE TO NRC GENERIC LETTER 98-04 i l

Northern States Power Company, a Minnesota corporation, by letter dated November 11, j 1998, provides the required 120 day response to NRC Generic Letter 98-04, " Potential for l Degradation 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 Materialin Containment."

l This letter contains no restricted or other defense information.

NORTHERN STATES POWER COMPANY By - (144t/J s Michael f. Hammer '

Plant Manager Monticello Nuclear Generating Plant On this \ day of o9 evber \%8 before me a notary public in and for said County, personally appeared Michael F. Hammer, Plant Manager, Monticello Nuclear Generating Plant, and being first duly sworn acknowledged that he is authorized to execute this document on behalf of Northern States Power Company, that he knows the contents thereof, and that to the best of his knowledge, information, and belief the statements made in it are true ar'd that it is not interposed for delay.

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' Samuel 1. Shirey SAMUkL i. SHIREY ,

C. Q*) p Notary Public - Minnesota u-MEWA  ;

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My Commission Expires January 31,2000 t

l GENERIC LETTER 98-04 REQUESTED INFORMATION l

(1) A summary description of the plant-specific program or programs 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 licensing basis for l the facility. Include a discussion of how the plant-specific program meets the j applicable criteria of 10 CFR Part 50, Appendix B, as well as information l regarding any applicable standards, plant-specific procedures, or other j l guidance used for: (a) controlling the procurement of coatings and paints  !

l used at the facility,(b) the qualification testing of protective coatings, and (c) l i surface preparation, application, surveillance, and maintenance activities for l protective coatings. Maintenance activities involve reworking degraded  !

coatings, removing degraded coatings to sound coatings, correctly preparing i

the surfaces, applying new coatings, and verifying the quality of the coatings.

RESPONSE

Northern States Power Company has implemented controls for the procurement, application, and maintenance of Service Level 1 protective coatings used inside the l

containment in a manner that is consistent with the licensing basis and regulatory requirements applicable to Monticello. The requirements of 10 CFR 50 Appendix B are implemented through specification of appropriate technical and quality requirements for the Service Level I coatings program which includes ongoing maintenance activities, i For Monticello, Service Level l' coatings are subject to the requirements of ANSI N101.4-1972, to the extent specified in ANSI N18.7-1976 and as modified by Regulatory l

. Guide 1.54, June,1973. Adequate assurance that the applicable requirements for the procurement, application, inspection, and maintenance are implemented is provided by procedures and programmatic controls, approved under the Northern States Power Quality Assurance program. These requirements were not part of the original licensing j basis for Monticelio. Generally accepted practices were used for Service Level 1 coatings applied prior to the time that the ANSI Standard and Regulatory Guide requirements were incorporated into the plant's licensing basis via Revision 2 of the Northern States Power Operational Quality Assurance Plan on November 15,1977.

Ilowever, the coating systems used on the majority of the coated surface area inside containment have since been qualified by the coating manufacturer for DBA conditions.

' Our response applies to Service Level I coatings used inside primary containtnent that are procured, I applial and maintainu! by Monticello. This response does not address the relatively small amount of

coatings applied by vendors on supplial equipment and miscellanu>us structural supports.  ;

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l (a) Service Level I coatings used for new applications or ":paireicplacement activities

.- are. procured from a vendor (s) with a quality assurance program meeting the applicable requirements of 10 CFR 50 Appendix B. The applicable technical and quality requirements which the vendor is required to meet are specified in procurement documents. Acceptance activities are conducted in accordance with -

procedures which are consistent with ANSI N 45.2 requirements (e.g., receipt inspection, source surveillance, etc.). This specification of required technical and quality requirements combined with appropriate acceptance activities provides

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l adequate assurance that the coatings received meet the requirements of the procurement documents.

(b) The quali0etion testing of Service Level I coatings used for new applications or l repair /rtplacement activities inside containment meets the applicable requirements I l contained in the standards and regulatory commitments referenced above.

' (c) The surface preparation, application and surveillance during installation of Service Level 1 coatings used for new applications or repair / replacement activities inside containment is controlled and documented by Procedure 8236, APPLICATION OF NUCLEAR COATINGS, or Procedure 8280, TORUS PAINTING. These procedures implement the applicable portions of the standards and regulatory commitments referenced above.

Monticello periodically conducts condition assessments of Service Level I coatings inside containment. Coating condition assessments are conducted as part of Technical Specification Surveillance Procedures 0135, PRESSURE-SUPPRESSION CHAMBER PAINTED SURFACE INTERNAL INSPECTION, and 0140, DRYWELL INTERIOR SURFACE INSPECTION. These surveillance requirements are required to be performed once each operating cycle. Since the suppression chamber surveillance requirement is only for the water line region and above, Procedure 1367, PRESSURE-SUPPRESSION CIIAMBER BELOW WATER LINE PAINTED SURFACE l

INTERNAL INSPECTION, is performed once every five years. When localized areas of degraded coatings are identified, those areas are evaluated and scheduled for repair or replacement, as necessary. These periodic condition assessments, and the resulting repair / replacement activities, assure that the amount of Service Level I coatings which may be susceptible to detachment from the substrate during a LOCA event is minimized.

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.(2) ..Information 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 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.

(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 determine this limit.

1 (c) If a commercial-grade dedication program is being used at your l facility for dedicating commercial-grade coatings for Service I.evel 1 l 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.

(ii) For plants without the above licensing-basis requirements,information shall be provided to demonstrate compliance with the requirements of 10CFR50.46(b)(5), Long-term cooling, and the functional capability of the safety-related CSS as set forth in your licensing basis. If a licensee can demonstrate this compliance without quantifying the amount of unqualified coatings, this is acceptable. The following information shall be provided:

(a) If commercial-grade coatings are being used at your facility for Service Level 1 applications, and such coatings are not dedicated or controlled under your Appendix B Quality Assurance Program, l 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.

RESPONSE

Monticello does not have a licensing basis requirement for tracking the quantity of unqualified coatings in containment. To meet the requirements of 10CFR50.46(b)(5) for long-term cooling and containment spray functional requirements, suction water to the i

ECCS pumps is taken from a common ring header that has four suction lines connected to strainer assemblies located in the torus. He torus penetrations and the strainer Page 3 of 5

l assemblies are positioned above the bottom of the suppression pool and below ine pool l s.urface to minimize the risk of plugging from debris. Sufficient flow area is available to l meet flow requirements for long-term cooling and containment spray functional requirements with one completely plugged strainer assembly. Additionally,in response to NRC 13ulletin 96-03, large passive replacement ECCS suction strainers have recently been installed at Monticello. Consequently the following discussion addresses the anticipated licensing basis pending resolution of NRC 13ulletin 96-03 and should not be interpreted as new commitments. j i

The design input to the ECCS strainer calculations for the amount of unqualified l coatings, qualified coatings in steam /waterjet zone ofinfluence, and degraded qualified coatings in the containment (as identified from periodic visual inspections) will be documented in the new ECCS strainer hydraulic calculations. Consequently 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 l l

capability of the ECCS is not compromised.

l The new ECCS suction strainers have been designed to perform satisfactorily in the presence of the containment coatings which are detached from the containment shell in the LOCA pipe break steam /waterjet zone ofinfluence. This amount of coating debds was 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, as documented in the Safety Evaluation Repon (SER) on the URG, Project No. 691, August 20,1998.

l An additional amount of coating debris will be considered to be present in the suppression pool. This amount will account for potential debris which may result from coatings which are unqualified and/or degraded. 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 l 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 the bottom of the suppression pool after the turbulence subsides, none of the unqualified coating debds (if eventually released sometime after the first 30 minutes of the LOCA) would be available to accumulate on the strainers. Therefore, the debris from unqualified coatings which has passed a visual inspection will not be included in the ECCS suction strainer design criteria. Ilowever, visual inspections of coating systems periodically identify small amounts of degraded coatings. Therefore, the design criteria for the ECCS suction strainers will account for potential debris from unqualified and/or degraded coatings which do not pass visualinspection. The evaluation of the impact of this additional debris will be made by Monticello specific strainer testing and /or BWR Owners' Group activities. Northern States Power Company is participating in the BWR Page 4 of 5

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l L Owners' Group Containment Coatings Committee and activities in progress are expected

. 16 result in an increase in the quantity of containment coating debris that can be

' accommodated on the strainers without challenging their functional capability.

Northern States Power Company does not currently employ commercial grade dedication l

~ for Service Level I coatings used for new applications or repair / replacement activities inside containment at Monticello.-

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