ML20217K550
| ML20217K550 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 04/24/1998 |
| From: | Hall J NRC (Affiliation Not Assigned) |
| To: | Horn G NEBRASKA PUBLIC POWER DISTRICT |
| References | |
| GL-96-06, GL-96-6, TAC-M96799, NUDOCS 9805040014 | |
| Download: ML20217K550 (5) | |
Text
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April 24, 1998
~
Mr. G. R. Hom Sr. Vice President of Energy Supply Nebraska Public Power District 141415th Street Columbus, NE 68601
SUBJECT:
COOPER NUCLEAR STATION - REQUEST FOR ADDITIONAL INFORMATION RELATED TO NRC GENERIC LETTER 96-06, ASSURANCE OF EQUIPMENT l
OPERABILITY AND CONTAINMENT INTEGRITY DURING DESIGN-BASIS i
ACCIDENT CONDITIONS" (TAC NO. M96799)
Dear Mr. Hom:
By letters dated January 28, March 27, and May 13,1997, the Nebraska Public Power District (NPPD) submitted its responses to NRC Generic Letter (GL) 96-06 for the Cooper Nuclear Station (CNS). The GL requested, in part, that licensees provide their evaluation of cooling water systems that serve containment air coolers, to assure that they are not vulnerable to waterhammer or two-phase flow conditions.
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The NRC staff has reviewed the information provided by NPPD in the above submittals. In order to complete our review of the resolution of the waterhammer and two-phase flow issues for CNS, we will require additional information, as discussed in the enclosure to this letter. We request your response to the enclosed questions by June 30,1998, in order to support our review schedule for GL 96-06.
If you have any questions regarding this request, please call me at (301) 415-1336.
Sincerely, i
ORIGINAL SIGNED BY:
James R. Hall, Senior Project Manager Project Directorate IV-1 Division of Reactor Projects lil/IV Office of Nuclear Reactor Regulation Docket No. 50-298 l
Enclosure:
Request for Additional Information cc w/ encl: See next page DISTRIBUTION w/o encl:
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April 24, 1998 l
Mr. G. R. Hom l
Sr. Vice President of Energy Supply l
Nebraska Public Power District 141415th Street Columbus, NE 68601 I
SUBJECT:
COOPER NUCLEAR STATION - REQUEST FOR ADDITIONAL INFORMATION l
RELATED TO NRC GENERIC LETTER 96-06," ASSURANCE OF EQUIPMENT OPERABILITY AND CONTAINMENT INTEGRITY DURING DESIGN-BASIS l
ACCIDENT CONDITIONS" (TAC NO. M96799)
Dear Mr. Hom:
By letters dated January 28, March 27, and May 13,1997, the Nebraska Public Power District (NPPD) submitted its responses to NRC Generic Letter (GL) 96-06 for the Cooper Nuclear l
Station (CNS). The GL requested, in part, that licensees provide their evaluation of cooling water systems that serve containment air coolers, to assure that they are not vulnerable to waterhammer or two-phase flow conditions.
)
The NRC staff has reviewed the infom1ation provided by NPPD in the above submittals. In order to complete our review of the resolution of the waterhammer and two-phase flow issues for CNS, l
we will require additionalinformation, as discussed in the enclosure to this letter. We request your response to the enclosed questions by June 30,1998, in order to support our review schedule for GL 96-06.
l If you have any questions regarding this request, please call me at (301) 415-1336.
l l
Sincerely, s,g mes R. Hall, Senior Project Manager j
roject Directorate IV-1 l
Division of Reactor Projects lil/IV Office of Nuclear Reactor Regulation Docket No. 50-298 i
Enclosure:
Request for AdditionalInformation i
cc w/ encl: See next page
i Mr. G. R. Hom Nebraska Public Power District Cooper Nuclear Station cc:
l Mr. John R McPhail, General Counsel Uncoln Electric System l
Nebraska Public Power District ATTN: Mr. Ron Stoddard l
P. O. Box 499 Box 80869 Columbus, NE 68602-0499 Uncoln, NE 68501 l
Nebraska Public Power District MidAmerican Energy ATTN: Mr. J. H. Swalles ATTN: Dr. William D. Leech, Manager-Nuclear Vice President of Nuclear Energy 907 Walnut Street P. O. Box 98 P. O. Box 657 Brownville, NE 68321 Des Moines, IA 50303-0657 Randolph Wood, Director Nebraska Department of Environmental Nebraska Public Power District Control ATTN: Mr. B. L. Houston, Nuclear i
P. O. Box 98922 Licensing & Safety Manager Lincoln, NE 68509-8922 P. O. Box 98 Brownville, NE 68321 Mr. Lany Bohlken, Chairman Nemaha County Board of Commissioners Nemaha County Courthouse 1824 N Street l
Aubum, NE 68305 Senior Resident inspector l
U.S. Nuclear Regulatory Commission P. O. Box 218 Brownville, NE 68321 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011 l
Ms. Cheryl Rogers, LLRW Program Manager Division of Radiological Health Nebraska Department of Health 301 Centennial Mall, South l
P. O. Box 95007 L
Lincoln, NE 68509-5007 Mr. Ronald A. Kucera, Department Director of Intergovemmental Cooperation Department of Natural Resources P.O. Box 176 Jefferson City, MO 65102
REQUEST FOR ADDITIONAL INFORMATION FOR RESOLUTION OF GL 96-06 ISSUES AT THE COOPER NUCLEAR STATION (TAC NO. M96799)
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 waterhammer and two-phase flow conditions. Nebraska Public Power District (the licensee) provided its assessment for the Cooper Nuclear Station in letters dated January 28, March 27, and May 13,1997. The licensee's response indicates that the containment air coolers are not safety-related and are cooled by the non-critical portion of the reactor equipment cooling (REC) system. However, the licensee leaves open the possibility of using the containment air coolers following an event, and has determined that a waterhammer event will not occur in the REC system. In order to adequately assess the licensee's resolution of the waterhammer and two-phase flow issues, the following additional information is requested:
1.
If a methodology other than that discussed in NUREG/CR-5220, " Diagnosis of Condensation-Induced Waterhammer," was used in evaluating the effects of waterhammer, describe this attemate methodology in detail. Also, explain why this methodology is applicable and gives conservative results for the Cooper Nuclear Station (typically accomplished through rigorous plant-specific modeling, testing, and analysis).
2.
For both the waterhammer and two-phase flow analyses, provide the following information:
a.
Identify any computer codes that were used in the waterhammer 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).
b.
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).
c.
Provide a detailed description of the " worst case" scenarios for waterhammer and two-phase flow, taking into consideration the complete range of event possibilities, system configurations, and parameters. For example, all waterhammer types and water slug scenarios should be considered, as well as temperatures, pressures, flow rates, load combinations, and potential component failures. Additional examples include:
the effects of void fraction on flow balance and heat transfer; ENCLOSURE
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the consequences of r, team formation, transport, and accumulation; cavitation, resonance, and fatigue effects; and erosion considerations.
Licensees may find NUREG/CR-6031, " Cavitation Guide for Control Valves,"
helpfulin addressing some aspects of the two-phase flow analyses.
d.
Confirm that the analyses included a complete failure modes and effects analysis (FMEA) for all components (including electrical and pneumatic failures) that could affect the severity of the waterhammer and confirm that the FMEA is documented and available for review, or explain why a complete and fully documented FMEA was not performed.
e.
Explain and justify all uses of " engineering judgement."
3.
Determine the uncertainty in the waterhammer 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 Cooper Nuclear Station.
4.
Confirm that the waterhammer 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 j
will maintain its integrity for all event scenarios and that the system isolation valves will j
remain operable.
5.
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, j
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