B17523, Provides Response to GL 98-04, Potential for Degradation of ECCS After LOCA Because of Construction & Protective Coating Deficiencies & Foreign Matl in Containment

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

ML20195E125
Person / Time
Site:	Millstone
Issue date:	11/12/1998
From:	Bowling M NORTHEAST NUCLEAR ENERGY CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
B17523, GL-98-04, GL-98-4, NUDOCS 9811180241
Download: ML20195E125 (12)

Text

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• . 1 l NMM Rope Ferry Rd. (Route 156), Waterford, CT 06385

, Nuclear Energy mistone Nocien, Power station Northeast Nuclear Energy Company P.O. Box 128 Waterford, CT 06385-0128 (860) 447-1791 Fax (860) 444 4277 The Nonheast Utilitica System NOV I 2 1998 Docket No. 50-336 B17523 Re: 10CFR50.54(f)

GL 98-04 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 l

Millstone Nuclear Power Station, Unit No. 2

, Response to Generic Letter.98-04 Potential For Degradation of The Emergency Core Cooling System After a Loss-of-Coolant Accident Because of Construction and Protective Coating Deficiencies and Forelan Materiaiin Containment i

This letter provides Northeast Nuclear Energy Company's-(NNECO) response to -  ;

p Generic Letter (GL) 98-04* regarding potential for degradation of the emergency core l cooling system after a loss-of-coolant accident because of construction and protective coating deficiencies and foreign material in containment.

I GL 98-04 requests that NNECO, within 120 days of the date of this generic letter, l submit a written response that includes the following information:

l (1) A summary description of the plant-specific program or programs implemented to r ensure that Service Level 1 protective coatings used inside the containment are L procured, applied, and maintained in compliance with applicable regulatory L requirements and the plant-specific licensing basis for the facility. Include a { ,j ,

i- 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

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i.,.j' ~" j ') the procurement testing of protectiveof coatings coatings, andand paints preparaUon, (c) surface used at theapplication, facility, (b) the qual l

surveillance, and maintenance activities for protective coatings. Maintenance activities involve reworking degraded coatings, removing degraded coatings to  !

h M GL 98-04, " Potential For Degradation of The Emergency Core Cooling System After a

. Loss-of-Cociant Accident Because of Construction and Protective Coating Deficiencies and Foreign Material in Containment," dated July 14,1998.

9811190241 981112  ?

PDR ADOCK.05000336,

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U.S. Nuclerr Rrgulatory Commission B17523/Page 2 l-

sound coatings, correctly preparing the surfaces, applying new coatings, and

. verifying the quality of the coatings.

(2) Information demonstrating compliance with :t 3m (i) or item (ii):

1 (i) For plants with licensing-basis requirements for tracking the amount of l unqualified coatings inside the containment and for assessing the impact of

( potential coating debris on the operation of safety-related SSCs during a l postulated DB LOCA, the following information shall be provided to i demonstrate compliance: l (a) The date and findings of the last assessment of coatings, and the planned l- date of the next assessment of coatings.

l l (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.

l-l (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. 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 l be provided to demonstrate compliance with the requirements of 10 CFR 50.46b(5), "Long-term cooling" and une functional capability of the safety-related CSS as set fo;th 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:

l (a)If commercial-grade coatings are being used at your facility for Service i

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

NNECO has reviewed the current licensing and design basis regarding 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

Emergency Core Cooling System (ECCS) and the safety-related containment spray i

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' I U.S.' Nuclitr Rtguintory Commission l B17523/Page 3 system (CSS). Attachment 1 provides NNECO's response for the request of l information contained in GL 98-04. l l

There are no regulatory commitments contained within this letter. Should you have any  !

- questions regarding this submittal, please contact Mr. Ravi G. Joshi at (860) 440-2080.

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Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY 1

Martin L. Bowling, Jr. (/

Recovery Officer - Technical Services Swom to and subscribed before me this day o h .1998 A Public C

My Commission expires MY COMMISSION EXPIRES JUNE 30,2004 i

i Attachment cc: H. J. Miller, Region i Administrator D. G. Mcdonald, Jr., NRC Senior Project Manager, Millstone Unit No. 2 D. P. Beaulieu, Senior Resident inspector, Millstone Unit No. 2

' E. V. Imbro, Director, Millstone ICAVP inspections S. Dembek, NRC Project Manager, Millstone Unit No.1 l

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Docket No. 50-336  !

, B17523 i

Attachment 1 l

Millstone Nuclear Power Station, Unit No. 2 Response to Generic Letter 98-04 Potential For Degradation of The Emergency Core Cooling System After a Loss-of-Coolant Accident Because of Construction and Protective Coating Deficiencies and i l Foreign Materialin Containment  !

. Requested Information l'

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November 1998

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l U.S. Nucl=r Regulatory Commission l B17523/ Attachment 1/Page 1 Respon'se to Generic Letter 98-04 Requested Information

Introduction:

The NRC issued Generic Letter (GL) 98-04 to alert the addressees to the problems associated with the material condition of Service Level 1 protective coatings inside the containment and t - request information under 10 CFR 50.54(f) to evaluate the addressees' progranis 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 Emergency Core Cooling System (ECCS) and the safety-related containment spray system (CSS). The following is Northeast Nuclear Energy Company's (NNECO) response to the requested information.

Response to Questions:

Question (1)

A summary description of the plant-specific program or programs l implemented to ensure that Service Level 1 protective coatings used inside the containment are procured, applied, and maintained in compilance with applicable regulatory requirements 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 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 of protective coatings, and (c) surface preparation, application, surveillance, and maintenance activities for protective coatings. Maintenance activities involve reworking deyaded coatings, removing degraded coatings to sound coatings, correctly preparing the ~" es, applying new coatings, and verifying the quality of the coatings.

RESPONSE to (1):

Northeast Nuclear Energy Company (NNECO) 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 Millstone Nuclear Power Station, Unit No. 2 (MP2). The requirements of 10 CFR Part 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.

Currently, Millstone Unit No. 2 Service Level 1 maintenance coatings are subject to the requirements of Regulatory Guide 1.54. Service Level 1 applies to coatings used in the primary containment which are procured, applied and maintained by NNECO or 4 - _, , _

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!' U.S. Nucicer R:gulatory Commission

' B17523/ Attachment 1/Page 2 their contractor. Maintenance coating materials are required to be tested to withstand Millstone Unit No. 2 design basis loss of coolant accident (DBA-LOCA) conditions.

Current requirements for coating materials and their application comply with Regulatory Guide 1.54 with the following clarifications and exceptions as stated in FSAR Section 5.9.3.7:

1) Compliance with Regulatory Guide 1.54 will not be invoked for equipment of a miscellaneous nature and insulated surfaces. It is impractical to impose Regulatory Guide requirements on the standard shop process used in painting valve bodies, handwheels, electrical cabinetry, control panels, loud speakers, emergency light cases, and other miscellaneous equipment. Wrapped or rigid insulation captures and retains any coating which may come off equipment surfaces, thereby preventing the coating material from reaching and blocking sump drains or interrupting water flow in the containment recirculation system.

2) Quality Assurance Program recommendations stated in Regulatory Guide 1.54 for the major equipmant and structures are followed except that inspection will be in accordance with action 10 of ANSI N5.12-1974 in lieu of Section 7 of ANSI N5.9 as referenced in Section 6.2.4 of ANSI N101.4.

3) Each coating was tested in accordance with ASTM D3911, " Evaluating Coatings Used in Light-Water Nuclear Power Plants at Simulated Design Basis f.ccident (DBA) Conditions." Prior to exposure to DBA conditions, each coating was irradiated to an accumulated dose in accordance with ASTM D4082, "Effect of Gamma Radiation on Coatings for Use in Light-Water Nuclear Power Plants."

During original construction, MP2 was not licensed to Regulatory Guide 1.54.

However, MP2 was committed to ANSI N101.2 for use in the selection and evaluation of coatings for Service Level 1 areas. Per FSAR Section 5.9.3.6, containment coating materials for original construction have been tested by their manufacturers under simulated operating and incident conditions and certified to fully comply with the requirements of ANSI N101.2 (1972).

Adequate assurance that the applicable requirements for the procurement, application, inspection, and maintenance are implemented is currently provided by procedures and programmatic controls, approved under the NNECO Quality Assurance program. A Service Level 1 specification and procedures for MP2 provide technical, quality and procedural requirements for the application of protective coatings inside containment.

NNECO is evaluating the guidance provided in EPRI TR-109937 " Guideline on Nuclear Safety-Related Coatings" and, as appropriate, improvements to our existing programs and procedures for Service Level 1 coatings will be made.

(a) Procurement of Service Leve! 1 coatings used for new applications or repair / replacement activities are procured from vendor (s) with a quality assurance program meeting the applicable requirements of 10 CFR Part 50 Appendix B. The

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U.S. ' Nuclear Regulatory Commission j B17523/ Attachment 1/Page 3 applicable technical and quality requirements that the vendor is required to meet

are specified by NNECO in procurement documents. Acceptance activities are i conducted in accordance with procedures that are consistent with ANSI N45.2 1 requirements. This specification of technical and quality requirements combined with appropriate acceptance activities provides assurance that the coatings

received meet the requirements of the procurement documents. l t

j (b)The qualification testing cf Service Level 1 coatings used for new applications or i repair / replacement activities inside containment meets the applicable requirements

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contained in the standards and regulatory commitments referenced above. These l coatings have been evaluated to meet the applicable standards and regulatory requirements previously referenced.

l (c) The surface preparation and application of Service Level 1 coatings for both new l

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applications or repair / replacement activities inside containment meet the applicable portions of the standards and regulatory commitments referenced above. The i technical and quality requirements for application of protective coatings to exposed 3

surfaces of steel, concrete, and equipment within Primary Containment areas at Millstone Unit No. 2 are established by an approved Service Level 1 coatings specification and procedures. Documentation is consistent with the applicable requirements.

NNECO maintains coatings in accordance with its overall maintenance program for MP2. Repairs of coatings in accordance with approved procedures are performed in conjunction with miscellaneous inspection, maintenance and modification activities.

As a result of miscellaneous activities inside containment, any other localized areas of degraded coatings can be identified. Those costed areas would then be evaluated and scheduled for repair or replacement, as necessary. NNECO is evaluating the guidance provided in EPRI TR-109937, " Guidance on Nuclear Safety-Related Coatings," for l performing condition assessments of containment coatings.

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Question (2) information demonstrating compliance with item (i) or item (ii):

i (i) For plants with licensing-basis requirements for tracking the amount of l 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.

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U.S. Nuct:cr Regulatory Commission B17523/ Attachment 1/Page 4 l (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) N a commercial-grade dedication program is being used at your facility for dedicating commercial-grade coatings for Service Level 1 l applications inside the containment, discuss how the program l adequately qualifies such a coating for Service Level' 1 service. Identify l which standards or other guidance are currently being used to

dedicate containment coatings at your facility; or, l RESPONSE to 2 (1)

1 This item is not applicable for Millstone Unit No. 2. A response to item (ii) is provided below.

l First part of 2 (ii)

(ii) For plants without the above licensing-basis requirements, information shall be provided to demonstrate compliance with the requirements of 10CFR50.46b(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 l unqualified coatings, this is acceptable.

RESPONSE to first part of 2 (ii):

The following description and referenced materials provides the licensing basis for Millstone Unit No. 2 relative to conformance with 10 CFR 50.46(b)(5), "Long-term Cooling," specifically with regard to MP2's ability to provide extended decay heat removal including related assumptions for debris that could block containment emergency sump screens:

, Millstone Unit No. 2 FSAR Section 6.1, " Engineered Safety Features System" describes the licensing basis for systems that provide containment heat removal, including assumptions for the design of the containment sump. The specific sections of the FSAR which address emergency core cooling are Section 6.2, " Refueling Water i Storage Tank and Containment Sump," Section 6.3, " Safety injection System," and i

Section 6.4, " Containment Spray System." These sections provide the design bases including functional requirements, applicable design criteria and a system description.

l The Emergency Core Cooling System (ECCS) provides borated water to cool the i reactor core following a major Loss of Coolant Accident (LOCA). It consists of three 4

U.S. Nuclecr Regulatory Commission B17523/ Attachment 1/Page 5 subsystems that maintain the reactor core in a cool conditior' The three subsystems are the Safety injection (SI) system, the Containment Spray (CS), and Shut-down I

Cooling (SDC).

The SI system injects borated water into the reactor coolant system to cool the reactor core following a major loss of coolant accident. The injection system also provides continuous long-term cooling of the core by recirculation of borated water from the containment sump.

The Refueling Water Storage Tank (RWST) is the water source for cooling the core at the onset of a LOCA. When the RWST reaches its low setpoint, recirculation from the containment sump begins to maintain long term cooling.

l The CS system removes heat by spraying cool borated water through the containment atmosphere. The sprayed heated water is then collected in the containment sump and cooled by the reactor bui! ding closed cooling water system through the SDC heat exchangers and recirculated through spray nozzles into the containment atmosphere.

The SDC heat exchangers and the low pressure safety injection pumps are used during plant operations to remove core decay heat and primary coolant system sensible heat.

Following cooldown they are used to maintain a constant primary coolant system temperature while the plant is at cold shutdown.

Containment Sump The containment sumps are located at the bottom of the containment building at elevation (-)22'-6" and are provided with enclosures around the recirculation pump suction pipes. The borated water from the safely injection, containment spray system and reactor coolant system is collected and subsequently recirculated to the pump's suction. Two 24 inch containment recirculation pipes are provided from the sump to the suction of the Si and CS pumps. The sump screen enclosure is a screen assembly constructed of a stainless steel frame and galv7nized grating to which a stainless steel wire cloth is attached. The screen assembly is divided into two sections separated by mesh and grating. It is sized such that any particle that penetrates the screen is capable of passing through the engineered safety features' components. A failure of one side would not negate the operation of the remaining assembly.

Due to the low-face velocity across the sump screen, loose objects generated by a pipe break will either settle on the sump screen prior to sump operation or not be affected by sump operation. Loose objects most likely to block the sump screen would be sections of pipe insulation dislodged by a LOCA. The insulation debris generated from a LOCA in the steam generator cubicle (worse case) is assumed to be fine

, fragments. For design basis with one LPSI pump failing to trip on initiation of l recirculation switchover, insulation can be transported to and adhere on the sump 1

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U.S. Nuclur Regulatory Commission B17523/ Attachment 1/Page 6 screen. However, if no LPSI pump is operated in the recirculation mode, no insulation is expected to build up on the screens because of the low transport velocity.

Regulatory Guide 1,82 Millstone Unit No. 2 sump design has been reviewed against the guidance of Regulatory Guide 1.82 (RG 1.82). Although not a design basis / licensing basis requirement for MP2, engineering reviewed Regulatory Guide 1.82, " Water Source for Long Term Recirculation Cooling Following a Loss-of Cooling Accident," to compare MP2's present design with the latest requirements, in 1996, the existing sump screen was redesigned using RG 1.82 as guidance.

Generic Letter 97-04 Response in response to Generic Letter 97-04, dated January 5,1998, NNECO provided a review of the current design-basis analysis used to determine the available Net Positive Suction Head (NPSH) for the ECCS and containment heat removal pumps of MP2. A description of the methodology used to calculate head loss associated with the containment sump screen was provided. This included analysis of factors such as tho amount of insulation debris, sump screen area and sump water approach velocities to estimate the pressure drop across the sump screen mesh. Based on this review, NNECO concluded that:

. The head loss associated with the containment sump screen has been adequately calculated.

. The Millstone Unit No. 2 most recent ECCS analysis is different from the analysis reviewed and approved by the NRC for which a safety evaluation was issued.

. The NPSH analysis for the containment spray pumps is the same as the analysis reviewed and approved by the NRC for which a safety evaluation was issued.

. Containment overpressure was not credited in any ECCS NPSH calculation.

. The available NPSH for the HPSI pumps, in the recirculation mode, meets the required NPSH.

. Further analysis is required to confirm that there is adequate NPSH for the Containment Spray pumps.

NNECO committed to provide a written response, prior to the restart of MP2, to provide the results of the updated analyses of NPSH for the CS pumps.

In a response to a Request for Additionci information, dated June 18,1998, NNECO provided the supplemental information relating to the original response to Generic Letter 97-04 regarding NPSH for emergency core cooling and containment heat removal pumps. This included an updatec analysis of NPSH icr the Containment

' Spray Pumps. The analysis shows adequate NPSH margin and meets the Millstone

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U.S. Nucigar Rngulatory Commission l 817523/ Attachment 1/Page 7 j (Jnit No. 2 Licensing Basis. The NRC, in a letter dated July 7,1998, indicated that the I

, staff had reviewed the response provided by NNECO under GL 97-04 and concluded  !

that the requested information had been provided. The staff considers GL 97-04 l

. closed for MP2.  !

Summary:

Although the response to GL 97-04 provides the basis for current compliance with NPSH margin and long term cooling capability, NNECO recognizes the potential need to address the combination of fiber and unqualified coating debris. Since MP2 has no current licensing basis requirements to track amounts of unqualified coatings, NNECO is assessing the status of current coating systems inside containment to confirm their identification and also to establish the present condition of these coating systems as I applied. NNECO is also evaluating the potential impact that quantities of unqualified

) coating and insulation debris may have on containment sump screen head loss. This will address the effect that unqualified coating debris may have on overall sump l performance and therefore long-term cooling capability.

References:

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1. Millstono 2, FSAR, Chapter 6.2, " Refueling Water Storage Tank and Containment Sump."

2. Millstone 2, FSAR, Chapter 6.3, " Safety injection System."

3. Millstone 2, FSAR, Chapter 6.4, " Containment Spray System."

4. M. L. Bowling to Nuclear Regulatory Commission, " Millstone Power Station, Unit No. 2, 90 Day Response to Generic Letter 97-04, Assurance of Sufficient Net Positive Suction Head for Emergency Core Cooling and Containment Heat removal Pumps," dated January 5,1998.

5. M. L. Bowling to Nuclear Regulatory Commission, " Millstone Power Station, Unit j No. 2, 90 Day Response to Generic Letter 97-04, Assurance of Sufficient Net Positive Suction Head for Emergency Core Cooling and Containment Heat removal 1 Pumps, Response to Request for Additional Information," dated June 18,1998.

6. Safety Evaluation of the Millstone Nuclear Power Station Unit No. 2, Docket No.

50-336, dated May 10,1974.

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U.S. Nuclar Regulatory Commission

817523/ Attachment 1/Page 8

Second part of 2 (ii)

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 accordance with such

, a program. - Additionally, explain why the facility's licensing basis does not 4

require such a program.

RESPONSE to second part of 2 (ii)::

1 NNECO does not currently employ commercial grade dedication for Service Level 1 coatings used inside containment at Millstone Unit No. 2.

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