ML17059C053
| ML17059C053 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 06/01/1998 |
| From: | Hood D NRC (Affiliation Not Assigned) |
| To: | Mueller J NIAGARA MOHAWK POWER CORP. |
| References | |
| GL-96-06, GL-96-6, TAC-M96836, TAC-M96837, NUDOCS 9806030452 | |
| Download: ML17059C053 (14) | |
Text
Mr. John H. Mueller
'. Chief Nuclear Officer Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station Operations Building, Second Floor P.O. Box 63 Lycoming, NY 13093 3une 1,
1998
SUBJECT:
REQUEST FOR ADDITIONALINFORMATION REGARDING GENERIC LETTER 96-06 RESPONSE FOR NINE MILE POINT STATION, UNIT 1 AND2 (TAC NOS. M96836 &
M96837)
Dear Mr. Mueller.
The NRC staff, is reviewing your submittal of February 7, 1997, regarding Generic Letter 96-06, "Assurance of Equipment Operability and Containment Integrity During Design Basis Accident Conditions", for Nine Mile Point Nuclear Station, Units 1 and 2. We find that additional information is necessary to complete our review.
Your response to the enclosure is requested by August 30, 1998, to support our current review schedule.
Ifyou have questions regarding the enclosure or are unable to meet the requested response date, please contact me by phone at (301) 415-3049 or by e-mail at dshonrc.gov.
Sincerely, Original Signed by:
Docket Nos. 50-220 and 50-410
Enclosure:
Request for Additional Information Darl S. Hood, Senior Project Manager Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation cc w/encl: See next page DISTRIBUTION:
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Mr. John H. Mueller ffr~'; Chief Nuclear Officer Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station Operations Building, Second Floor P.O. Box 63 Lycoming, NY 13093 0une 1, 1998
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'UBJECT:
REQUEST FOR ADDITIONALINFORMATION REGARDING GENERIC LETTER 96-06 RESPONSE FOR NINE MILEPOINT STATION, UNIT 1 AND2 (TAC NOS. M96836 8 M96837)
Dear Mr. Mueller:
The NRC staff, is reviewing your submittal of February 7, 1997,'regarding Generic Letter 96-06, "Assurance of Equipment Operability and Containment Integrity During Design Basis Accident Conditions", for Nine Mile Point Nuclear Station, Units 1 and 2. We find that additional information is necessary to complete our review.
Your response to the enclosure is requested by August 30, 1998, to support our current review schedule.
Ifyou have questions regarding the enclosure or are unable to meet the requested response date, please contact me by phone at (301) 415-3049 or by e-mail at dsh@nrc.gov.
Sincerely, Original Signed by:
Darl S. Hood, Senior Project Manager Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket Nos. 50-220 and 50-410
Enclosure:
Request forAdditional Information ccw/encl: See next page DISTRIBUTION:
Docket File SBajwa PUBLIC SLittle
'DI-1 R/F DHood BBoger BWetzel JZwolinski 'Tatum OGC ACRS CCowgill, RI ARubin DOCUMENT NAME: G:hNMP1)NM96836.RAI To receive a copy of this document, indicate in the box: "G" = Copy without attachment/enclo ure "E" = Copy with attachment/enclosure "N"= No co OFFICE MAHE DATE PH:PDI-1 E
PH:PDI-1 DHood/ICC JCushing
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i UNITED STATES NUCLEAR REGULATORY COMIVllSSION WASHINGTON, D.C. 2055&0001 3une 1,
1998 Mr. John H. Mueller Chief Nuclear Officer Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station Operations Building, Second Floor P.O. Box 63 Lycoming, NY 13093
SUBJECT:
REQUEST FOR ADDITIONALINFORMATION REGARDING GENERIC LETTER 96-06 RESPONSE FOR NINE MILEPOINT STATION UNITS, 1 AND2 (TAC NOS. M96836 8 M96837)
Dear Mr. Mueller:
The NRC staff, is reviewing your submittal of February 7, 1997, regarding Generic Letter 96-06, "Assurance of Equipment Operability and Containment Integrity During Design Basis Accident Conditions", for Nine Mile Point Nuclear Station, Units 1 and 2. We find that additional information is necessary to complete our review.
Your response to the enclosure is requested by August 30, 1998, to support our current review schedule.
Ifyou have questions regarding the enclosure or are unable to meet the requested response date, please contact me by phone at (301) 415-3049 or by e-mail at dshonrc.gov.
Sincerely, Docket Nos. 50-220 and 50-410 Darl S. Hood, Senior Project Manager Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Enclosure:
Request for Additional Information ccw/encl: See next page
0 John H. Mueller Niagara Mohawk Power Corporation CC:
Regional Administrator, Region I
U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 126 Lycoming, NY 13093 Mr. Jim Rettberg New York State Electric & Gas
-Corporation Corporate Drive Kirkwood Industrial Park P.O. Box 5224 Binghamton, NY 13902-5224 Supervisor Town of Scriba Route 8, Box 382 Oswego, NY 13126 Mr. Richard Goldsmith Syracuse University College of Law E.l. White Hall Campus
- Syracuse, NY 12223 Mr. John V. Vinquist, MATS Inc.
P.O. Box 63 Lycoming, NY 13093 Nine Mile Point Nuclear Station Unit Nos.
1 and 2 Charles Donaldson, Esquire Assistant Attorney General New York Department of Law 120 Broadway New York, NY 10271 Mr. Paul D. Eddy State of New York Department of Public Service Power Division, System Operations 3 Empire State Plaza
- Albany, NY 12223 Mr. Timothy S. Carey Chair and Executive Director State Consumer Protection Board 5 Empire State Plaza, Suite 2101 Albany, NY 12223 Mark J. Wetterhahn, Esquire Winston & Strawn 1400 L Street, NW Washington, DC 20005-3502 Gary D. Wilson, Esquire Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, NY 13202 Mr. F. William Valentino, President New York State Energy, Research, and Development Authority Corporate Plaza West 286 Washington Avenue Extension Albany, NY 12203-6399
REQUEST FOR ADDITIONALINFORMATION REGARDING THE GL 96-06 RESPONSE NIAGARAMOHAWKPOWER CORPORATION NINE MILE POINT NUCLEAR STATION UNIT NOS.
1 AND 2 OPERATING LICENSE NUMBER DPR-63 AND NPF-69 DOCKET NOS. 50-220 AND50<10 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 condition's.
Niagara Mohawk Power Corporation (the licensee) provided its assessment of the waterhammer and two-phase flow issues for Nine Mile Point 1 and 2 in a letter dated February 7, 1997. The licensee indicated that the drywell air coolers at Nine Mile Point 1 and 2 are cooled by the Reactor Building Closed Loop Cooling (RBCLC) system. 'The drywell air coolers are not safety-related and are not credited in the mitigation of a design-basis accident, but may be used post-accident ifavailable as allowed by the Emergency Operating Procedures (EOPs). The licensee concluded that waterhammer and two-phase flow conditions willnot occur during post-accident operation of the drywell air coolers on Unit 1 due to the elevation head that is available'in the RBCLC Makeup Tank, and indicated that the Unit 2 EOPs have been revised to prevent post-accident use of the drywell air coolers when drywell temperatures exceed 250 'F and waterhammer could occur.
In order to assess the licensee's resolution of these issues, the NRC staff requires the following additional information regarding waterhammer and two-phase flow assessments associated with post-accident operation of the drywell air coolers.
Unit'1:
Discuss specific system parameter requirements to be maintained to assure that waterhammer willnot occur in the RBCLC'system (RBCLC makeup tank level requirements, temperature requirements, etc.), and state the minimum margin to boiling that will exist for the worst-case scenario, including consideration of measurement and analytical uncertainties.
Describe and justify reliance on any non-safety related instrumentation and controls for assuring that waterhammer willnot occur, and explain why it would not be appropriate to establish Technical Specification requirements for maintaining these parameters.
2.
Unit 2:
For the small break scenario, describe the minimum time required for operators to initiate RBCLC flow in order to prevent steam formation, and explain how this action will be assured.
Although the EOPs have been revised to eliminate the potential for waterhammer following a large-break loss-of-coolant accident, explain how waterhammer willbe avoided.
after drywell temperature drops below 250 'F (steam pockets that have been formed are not expected to dissipate. very readily).
3.
Unit 1 and Unit 2:
Implementing measures to assure that waterhammer willnot occur, such as maintaining system static pres" ure or prohibiting post-accident operation of the affected system,.is an acceptable approach for addressing the waterhammer concern.
However, all Enclosure
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'cenarios should be considered to assure'that the vulnerability to waterhammer has been eliminated.
Confirm that all scenarios have been considered, including those where the affected containment penetrations are not isolated (ifthis 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.
4.
Unit 1 and Unit 2:
For those scenarios where the potential for two-phase flow has not been eliminated, explain
'o what extent two-phase flow conditions willexist following accident conditions and 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).
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.,
fluid structure interaction, flowinduced vibration, erosion).
c.
Provide a detailed description of the "worst case" scenario for two-phase flow, taking into consideration the complete range of event possibilities, system configurations, parameters (e.g., temperatures, pressures, flow rates, load combinations), and component failures. Additional examples 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.
(Note: it is important for licensees to realize that in addition to heat transfer considerations, two-phase flow also involves structural and system integrity concerns that should be addressed).
d.
Determine the uncertainty in the two-phase flowanalyses, explain how the uncertainty was determined, and how it was accounted for in the analyses to assure conservative results.
e.
Confirm that the 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.
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 willremain operable.
0 4
5.
Unit 1 and Unit 2:
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.
Also, confirm that the FMEA is documented and available for review, or explain why a complete and fully documented FMEAwas not performed.
6.
Unit 1 and Unit 2:
Explain and justifywhere engineering judgment was used in lieu of calculations in the analysis of the RBCLC system.
7.
Unit 1 and Unit 2:
Provide a simplified diagram of the affected cooling water systems showing major components, active components, relative'elevations, lengths of piping runs, and the location of any orifices and flow restrictions.
8.
Unit 1 and Unit 2:
Describe in detail any modifications that have been made (or will be made) to system design or operating requirements to resolve the waterhammer and two-phase flow issues.
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