ML20236V992

Forwards RAI Re GL 96-06, Assurance of Equipment Operability & Containment Integrity During Design-Basis Accident Condition, Dtd 960930. Response Requested by 981030

ML20236V992
Person / Time
Site:	Waterford
Issue date:	07/29/1998
From:	Chandu Patel NRC (Affiliation Not Assigned)
To:	Dugger C ENTERGY OPERATIONS, INC.
References
GL-96-06, GL-96-6, TAC-M96883, NUDOCS 9808050013
Download: ML20236V992 (5)

Text

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Mr. Charles M. Dugger July 29, 1998 Vice President Operations Entergy Operations, Inc.

P. O. Box B I Killons, LA 70066 l

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE GENERIC LETTER 96-06 RESPONSE FOR WATERFORD STEAM ELECTRIC STATION, UNIT 3 (TAC NO. M06883)

Dear Mr. Dugger:

Generic Letter (GL) 46-06, " Assurance of Equipment Operability and Containment integrity During Design-Basis Accident Conditions," dated September 30,1996, included a request for licensees to evaluate cooling water systems that serve containment air coolers to assure that they are not vulnerable to waterhammer and two-phase flow conditions. Entergy Operations, Inc. ( EOI) provided its assessment of the waterhammer and two-phase flow issues for Waterford Steam Electric Station, Unit 3 (Waterford 3), in a letter dated January 28,1997. In order to complete our review of the EOl's resolution of these issues, we require additional information as discussed in the enclosure. Please provide this information by October 30,1998, in order to support our review schedule for GL 96-06.

Sincerely, ORIGINAL SIGNED BY:

Chandu P. Patel, Project Manager Project Directorate IV-1 i Division of Reactor Projects til/IV Office of Nuclear Reactor Regulation Docket No. 50-382 g,

Enclosure:

As stated rr- "

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t NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20066-0001 Y+4 ***** ,o July 29, 1998 Mr. Charles M. Dugger Vice President Operations Entergy Operations, Inc.

P. O. Box B Killona, LA 70066 l

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE GENERIC LETTER 96-06 RESPONSE FOR WATERFORD STEAM ELECTRIC STATION, .

UNIT 3 (TAC NO. M96883) )

Dear Mr. Dugger:

t Generic Letter (GL) 96-06, " Assurance of Equipment Operability and Containment I

(

integrity During Design-Basis Accident Conditions," dated September 30,1996, included a request for licensees to evaluate cooling water systems that serve containment air coolers to assure that they are not vulnerable to waterhammer and two-phase flow conditions. Entergy Operations, Inc. ( EOl) provided its assessment of the waterhammer and two-phase flow issues for Waterford Steam Electric Station, Unit 3 (Waterford 3), in a letter dated January 28,1997. In order to complete our review of the EOl's resolution of these issues, we require additional information as discussed in the enclosure. Please provide this information by October 30,1998, in order to support our review schedule for GL 96-06.

Sincerely, AJA f Chandu P. Patel, Project Manager Project Directorate IV-1 Division of Reactor Projects Ill/IV Office of Nuclear Reactor Regulation Docket No. 50-382

Enclosure:

As stated cc: See next page

Mr. Charles M. Dugger Entergy Operatione, Inc. Waterford 3 cc:

Ad.ninistrator Regional Administrator, Region IV Louisiana Radiation Protection Division U.S. Nuclear Regulatory Commission Post Office Box 82135 611 Ryan Plaza Drive, Suite 1000 Baton Rouge, LA 70884-2135 Arlington,TX 76011 Vice President, Operations Resident inspector /Waterford NPS Suppod Post Office Box 822 Entergy Operations, Inc. Killona, LA 703o0 P. O. Box 31995

. Jackson, MS 39286 Parish President Council St. Charles Parish Director P. O. Box 302 Nuclear Safety & Regulatory Affairs Hahnville,l.A 70057 Entergy Operations, Inc.

P. O. Box B Executive Vice-President Killona, LA 70066 and Chief Operating Officer Entergy Operations, Inc.

Wise, Carter, Child & Caraway P. O. Box 31995 P. O. Box 651 Jackson, MS 39286-1995 Jackson, MS 39205 Chairman General Manager Plant Operations Louisiana Public Service Commission Entergy Operations, Inc. One American Place, Suite 1630 P. O. Box B Baton Rouge, LA 70825-1697 Killona, LA 70066 Licensing Manager Entergy Operations, Inc.

P. O. Box B Killona, LA 70066 Winston & Strawn 1400 L Street, N.W.

l Washington, DC 20005-3502 l

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REQUEST FOR ADDITIONAL INFORMATION FOR RESOLUTION OF GL 96-06 ISSUES AT WATERFORD 3 Generic Letter (GL) 96-06, " Assurance of Equipment Operability and Containment Integrity During Design-Basis Accident Conditions," dated September 30,1996, included a request for licensees to evaluate cooling water systems thet serve containment air coolers to assure that they are not vulnerable to waterhammer and two-phase flow conditions. Entergy Operations, incorporated (EOl) provided its assessment of the waterhammer and two-phase flow issues for Waterford 3 in a letter dated January 28,1997. The EOl has concluded that the component cooling water (CCW) system will not boil during the applicable event scenarios, due in part to the system overpressure established by the CCW surge tank. In order to assess the EOl's resolution of these issues, the following additional information is requested:

Notes: a. Inforrnation that has been submitted previously may be referred to and supplemented as necessary to provide a complete response to the staff's questions,

b. The following questions are applicable to the system configuration and analyses that are credited for the final resolution of the waterhammer and two-phase flow issues.

1. Provide a detailed description of the " worst case" scenarios that were identified, taking into consideration the complete range of event possibility,es, system configurations, and parameters. For example, the complete range of temperatures, pressures, flow rates, load combinations, and component failures should be considered consistent with the design basis of the plant. Describe the minimum margin to boiling that will exist.

2. Identify any computer codes that were used in the waterhammer and two-phase flow analyses and describe the methods used to validate and bench mark the codes for the specific application and loading conditions involved.

3. Describe and justify all assumptions and input parameters (including those used in any computer codes) that were used in the waterhammer and two-phase flow analyses, and provide justification for omitting any effects that may be relevant to the analyses. Confirm that these assumptions and input parameters are consistent with the existing design and licensing bases of the plant. Any exceptions should be explained and justified.

l 4. The January 28,1997, response indicated that the main steam line break ( MSLB) provides the worst-case temperature excursion in containment. After 17 seconds, the temperature is about 375' F at 44 psia. The EOl indicated that the partial pressure of steam is less than 23 psia and the corresponding saturation temperature is 235' F. The EOl concluded that the condensed steam (at 235' F) will coat the outside surface of the fan cooler tubes and because the saturation temperature for CCW is about 269' F (due to surge tank elevation), boiling will not occur in the CCW system. Discuss what effect the bulk containment temperature will have on the fluid film that costs the fan cooler tubes and on CCW temperature. Describe the bounding CCW temperature that will be reached, and explain why this temperature is assured to be conservative.

ENCLOSURE u

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5. Explain and justify all uses of " engineering judgement" that were credited in the waterhammer and two-phase flow analyses.

6. Discuss specific system operating parameters and other operating restrictions that must be maintained to assure that the waterhammer and two-phase flow analyses remain valid ~

(e.g., surge tank level, temperature, pressure), and explain why it would not be appropriate to establish Technical Specification requirements to acknowledge the importance of these parameters and operating restrictions. Also, describe and justify use of any non-safety related instrumentation and c6ntrols for maintaining these parameters.

7. Implementing measures to prevent waterhammer and two-phase flow conditions, such as establishing and maintaining system overpressure requirements, is an acceptable approach for addressing these issues. However, all scenarios must be considered to assure that the vulnerability to waterhammer and two-phase flow has been eliminated.

Confirm that all scenarios have been considered, such that the measures that have been established are adequate to address the waterhammer and two-phase flow concems -

during (and following) all applicable accident scenarios.

8. Confirm that the waterhammer and two-phase flow analyses included a complete failure modes and effects analysis (FMEA) for all components (including electrical and pneumatic failures) that could impact performance of the cooling water system and confirm that the FMEA is documented and available for review, or explain why a complete and fully documented FMEA was not performed.

, 9. Describe the uncertainties that exist in the waterhammer and two-phase flow analyses, i including uncertainties and shortcomings associated with the use of any computer codes, l and explain how these uncertainties were accounted for in the analyses to assure conservative results.

, 10. Provide a simplified diagram of the affected system, showing major components, active components, relative elevations, lengths of piping runs, and the location of any orifices and flow restrictions.

11. Describe in detail any plant modifications or procedure changes that have been made or are planned to be made to resolve the waterhammer and two-phase flow issues, including schedules for completion.

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