ML20216C156

Forwards Request for Addl Info Related to Fermi-2 Response to GL 96-06, Assurance of Equipment Operability & Containment Integrity During Design-Basis Accident Conditions

ML20216C156
Person / Time
Site:	Fermi
Issue date:	04/06/1998
From:	Kugler A NRC (Affiliation Not Assigned)
To:	Gipson D DETROIT EDISON CO.
References
GL-96-06, GL-96-6, TAC-M96811, NUDOCS 9804140352
Download: ML20216C156 (4)

Text

1 Mr. Douglas R. Gipson April 6, 1998 Senior Vice President Nuclear Generation Detroit Edison Company 6400 North Dixie Highway Newport, Michigan 48166 SUiUJECT: REQUEST FOR ADDITIONAL INFORMATION (RAI) RELATED TO THE FERMI-2 RESPONSE TO GENERIC LETTER 96-06, " ASSURANCE OF EQUIPMENT OPERABILITY AND CONTAINMENT INTEGRITY DURING DESIGN-BASIS ACCIDENT CONDITIONS" (TAC NO. M96811)

Dear Mr. Gipson:

The NRC issued Generic Letter (GL) 96-06, " Assurance of Equipment Operability and Containment Integrity During Design-Basis Accident Conditions," on September 30,1996. The

] GL included a request for licensees to evaluate cooling water systems that serve containment air coolers to assure that they are not vulnerable to water hammer and two-phase flow conditions. Detroit Edison Company provided its response to the GL for the Fermi plant in a letter dated January 28,1997. On &sptember 9,1997, the staff sent a request for additional information related to the GL to which Detroit Edison responded on October 17,1997.

Additional information, as discussed in the enclosure, is requested in order for the staff to complete its review. NRC requests that Detroit Edison respond by June 30,1998.

If you have any questions conceming this request, please contact me at (301) 415-2828.

Sincerely, ORIGINAL SIGNED BY Andrew'J. Kugler, Project Man'ager Pioject Directorate ill-1 Division of Reactor Projects ill/IV Office of Nuclear Reactor Regulation Docket No. 50-341  !

Enclosure:

As stated

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'Mr. Dsuglas R. Gipson Fermi 2 Detroit Edison Company cc:

John Flynn, Esquire .

Senior Attomey Detroit Edison Company.

2000 Second Avenue Detroit, Michigan 48226 Drinking Water and Radiological Protection Division Michigan Department of Environmental Quality 3423 N. Martin Luther King Jr Blvd P. O. Box 30630 CPH Mailroom Lansing, Michigan 48909-8130 U.S. Nuclear Regulatory Cornmission Resident inspector's Office 6450 W. Dixie Highway .

Newport, Michigan 48166 Monroe County Emergency Management Division 963 South Raisinville Monroe, Michigan 48161 Regional Administrator, Region lll U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, Illinois 60532-4351 Norman K. Peterson Director, Nuclear Licensing -

Detroit Edison Company Fermi 2 - 280 TAC

. 6400 North Dixie Highway Newport, Michigan 48166 August 1997

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j REQUEST FOR ADDITIONAL INFORMATION (RAI) RELATED TO i THE FERMI-2 RESPONSE TO GENERIC LETTER 96-06, " ASSURANCE OF l l EQUIPMENT OPERABILITY AND CONTAINMENT INTEGR.lTY DURING l l DESIGN-BASIS ACCIDENT CONDITIONS"(TAC NO. M96811) l 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 that serve containment air coolers to assure that they are not vulnerable to water hammer and two-phase flow conditions. Detroit Edison j Company (the licensee) provided its assessment for Fermi-2 in letters dated January 28, and i October 17,1997. The licensee's response indicated that the drywell coolers are not required for accident mitigation and that cooling water to the drywell coolers, provided by the Reactor Building Closed Cooling Water (RBCCW) system, is isolated automatically on high drywell pressure. However, since no positive measures have been taken to assure that RBCCW will be isolated upon event initiation and remain isolated, the following additional information is requested:

1. Provide a detailed description of the " worst case" scenarios for water hammer and two-phase flow, taking into consideration the complete range of event possibilities, system ,

configurations, and parameters. All situations should be considered, including scenarios where RBCCW is not isolated or where RBCCW is restored to service by plant operators. Also, all water hammer types and water slug scenarios should be considered, as well as temperatures, pressures, flow rates, load combinations, and potential component failures. Additional examples of things to consider include:

the consequences of steam formation, transport, and accumulation; cavitation, resonance, and fatigue effects; and erosion considerations.

Licensees may find NUREG/CR-6031, " Cavitation Guide for Control Valves," helpful in addressing some aspects of the two-phase flow analyses.

2. If a methodology other than that discussed in NUREG/CR-5220,

• Diagnosis of Condensation-induced Water hammer," was used in evaluating the effects of water hammer, describe this attemate methodology in detail. Also, explain why this methodology is applicable and gives conservative results for the Fermi plant (typically accomplished through rigorous plant-specific modeling, tesiing, and analysis).

3. Identify any computer codes that were used in the water hammer and two-phase flow analyses and describe the methods used to bench mark the codes for the specific loading conditions involved (see Standard Review Plan Section 3.9.1).

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4. Describe and justify all assumptions and input parameters (including those used in any computer codes) such as amplifications due to fluid structure interaction, cushioning, speed of sound, force reductions, and mesh sizes, and explain why the values selected give conservative results. Also, provide justification for omitting any effects that may be relevant to the analysis (e.g., fluid structure interaction, flow induced vibration, erosion).

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

6. Determine the uncertainty in the water hammer and two-phase flow analyses, explain how the uncertainty was determined, and how it was accounted for in the analyses to assure conservative results for the Fermi plant.

7. Confirm that the water hammer and two-phase flow loading conditions do not exceed any design specifications or recommended service conditions for the piping system and components, including those stated by equipment vendors; and confirm that the system will continue to perform its design-basis functions as assumed in the safety analysis report for the facility.

8. Explain and justify all uses of " engineering judgement."

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

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