ML20249B456
| ML20249B456 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 06/19/1998 |
| From: | Eaton R NRC (Affiliation Not Assigned) |
| To: | Roche M GENERAL PUBLIC UTILITIES CORP. |
| References | |
| GL-96-06, GL-96-6, TAC-M96843, NUDOCS 9806230156 | |
| Download: ML20249B456 (4) | |
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, (._4 5 June 19,' 1998' Mr Michael B. Roche
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SUBJECT:
[ REQUEST FOR ADDITIONAL INFORMATION REGARDING GENERIC LETTER 96-06 (TAC NO. M96843)
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Dear Mr. Roche:
The Nuclear Regulatory Commission (NRC) staff has reviewed your letters dated January 28,
. and February 26,1997, regarding the subject Generic Letter. In order to complete our review we will require additional information. The additional information needed is provided in the enclosure. in order to support our review schedule please provide the requested information by.
August 30,1998.
_. If you have questions regarding this request, please call me at (301) 415-3041.
Sincerely, Original signed by Ronald B. Eaton, Sonicr Project Manager Project Directorate 1-3 Division of Reactor Projects - 1/11 Office of Nuclear Reactor Regulation Docket No. 50-219
Enclosure:
As stated
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Emest L. Blake, Jr., Esquire Shaw, Pittman, Potts & Trowbridge 2300 N Street, NW Washington, DC 20037 Regional Administrator, Region i U.S. Nuclear Regulatory Commission 475 Allendale Road.
King of Prussia, PA 19406-1415 BWR Licensing Manager
. GPU Nuclear Corporation 1 Upper Pond Road Parsippany, NJ 07054 Mayor Lacey Township 818 West Lacey Road Forked River, NJ 08731 Licensing Manager Oyster Creek Nuclear Generating Station Mail Stop: Olte Emergency Bldg.
P.O. Box 388 Forked River, NJ 08731 Resident inspector c/o U.S. Nuclear Regulatory Commission P.O. Box 445 Forked River, NJ 08731 Kent Tosch, Chief New Jercey Department of Environmental Protection Bureau of Nuclear Engineering.
CN 415 Trenton, NJ 08625
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REQUEST FOR ADDITIONAL INFORMATION FOR RESOLUTION OF GENERIC LETTER (GL) 96-06 ISSUES AT
( OYSTER CREEK NUCLEAR GENERATING STATION GL 96-06, " Assurance of Equipment Operability and Containment Integrity During Design-Basis Accidont 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. General Public Utilities Corporation (the licensee) provided its assessment of the waterhammer and two-phase flow issues for Oyster Creek in letters dated January 28, and February 26,1997. The licensee indicated that the drywell cooling units and associated reactor building closed cooling water system are not safety-related and are not required for accident mitigation. However, the Emergency Operating Procedures (EOPs) did allow operators to m the drywell cooling units following an accident if available, and the EOPs were revised to e!irrinate the potential for waterhammer following a loss-of-coolant accident. In order to assess the licensee's resolution of these issues, the following additional information is requesled:
1.
Describe the revisions that were made to the EOPs to eliminate the potential for waterhammer. Also discuss to what extent these revisions eliminate the potential for two-phase flow.
2.
Implementing measures to assure that waterhammer will not occur, such as prohibiting post-accident operation of the affected system, is an acceptable approach for addressing the waterhammer concem. However, all scenarios must be considered to assure that the vulnerability to waterhammer has been eliminated. Confirm that all scenarios have been
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considered, including those where the affected containment penetrations are not isolated I
. (if this is a possibility), such that the measures that have been established are adequate to prevent the occurrence of waterhammer during (and following) all postulated accident scenarios.
I 3.
If the potential for two-phase flow has not been eliminated, provide the following information:
a.
Identify any computer codes that were used in the 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).
b.
Describe and justify all assumptions and input parameters (including those used in any computer codes) 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., flow induced vibration, erosion).
ENCLOSURE
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2-c.
- Provide a detailed description of the " worst case" scenario for tw@ase flow, taking into consideration the complete range of event possibilities, system configurations, parameters, and ee,T,perent failures. Additional examples include:
the consequences of steam formation, transport, and accumulation;-
cavitation, resonanos, and fatigue ofrects; 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. (Note: it is important for licensees to realize that in addition to heat transfer cons!derations, two-phase flow also involves structural and system integrity concoms that must be addressed.)
d.
Confirm that the two-phase flow loading conditions do not exceed any der,ign 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, and that the containment isolation valves will remain operable.
e.
Determine the uncertainty in the two-phase flow analyses, explain how the
' uncertainty was determined, and how it was accounted for in the analyses to assure conservative results, f.
Confirm that the 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.
g.
Explain and justify all uses of " engineering judgement."
4.
Provide a simplified diagram of the affected system, showing major components, active components, relative slovations, lengths of piping runs, and the location of any orifices and flow restrictions.
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