ML20217P008
| ML20217P008 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 04/30/1998 |
| From: | Richard Ennis NRC (Affiliation Not Assigned) |
| To: | Keiser H Public Service Enterprise Group |
| References | |
| GL-96-06, GL-96-6, TAC-M96821, NUDOCS 9805060037 | |
| Download: ML20217P008 (6) | |
Text
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3 April..~ 30, f1998
- ~
Mr. Harold W. Keiser ;
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Executive Vice President-
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l Nuclear Business Unit..
l-Public Service Electric & Gas l
Company '
L Post Office Box 236 Hancocks Bridge, NJ 08038
SUBJECT:
' REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE GENERIC l
L LETTER 96-06 RESPONSE FOR HOPE CREEK GENERATING STATION i
- (TAC NO. M96821) -
Dear Mr. Keiser:
Generic Letter (GL) 96-06, " Assurance of Equipment Operability and Containment Integrity-During Design-Basis Accident Conditions," issued by the NRC on 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. Public Service Electric and Gas Company provided its response for Hope Creek Generating Station in letter LR-N96439, dated January 27,1997. The NRC staff is reviewing and evaluating your response to GL 96-06. Additional information, as discussed in the enclosure, is requested in order for the staff to complete its review. We request that the additional information be provided -
within 60 days of receipt of this letter.'
if you have any questions, please contact me at (301) 415-1420.
Sincerely, 1
/S/
Richard B. Ennis, Acting Project Manager 1
Project Directorate 1-2 Division of Reactor Projects - 1/11 Office of Nuclear Reactor Regulation Docket No. 50-354 Enclosure': Request for Additional Information '
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April -30,1998 l
Mr. Harold W. Keiser i-Executive Vice President-Nuclear Business Unit Public Service Electric & Gas 1
Company Post Office Box 236 Hancocks Bridge, NJ 08038
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE GENERIC LETTER 96-06 RESPONSE FOR HOPE CREEK GENERATING STATION (TAC NO. M96821)
Dear Mr. Keiser:
Generic Letter (GL) 96-06, " Assurance of Equipment Operability and Containment Integrity During Design-Basis Accident Conditions," issued by the NRC on 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. Public Service Electric and Gas Company provided its response for Hope Creek Generating Station in letter LR-N96439, dated January 27,1997. The NRC staff is reviewing and evaluating your response to GL 96-06. Additionalinformation, as discussed in the enclosure, is requested in order for the staff to complete its review. We request that the additional information be provi< led within 60 days of receipt of this lettwr.
If you have any questions, please contact me at'(301) 415-1420.
Sincerely, s
Richard B. Ennis, Acting Project Manager Project Directorate 1-2
{
Division of Reactor Projects-1/il Office of Nuclear Reactor Regulation Docket No. 50-354
Enclosure:
Request for AdditjonalInformation cc w/ encl: See next page i
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Mr. Harold W. Keiser Hope Creek Generating Station -
Public Service Electric & Gas Company cc:
- Jeffrie J. Keenan, Esquire Manager-Joint Generation L
Nuclear Business Unit-N21 Atlantic Energy P.O. Box 236 6801 Black Horse Pike Hancocks Bridge, NJ 08038 Egg Harbor Twp.,' NJ.08234-413n Hope Creek Resident inspector _
Richard Hartung U.S. Nuclear Regulatory Commission '
~
' Electric Service Evaluation Drawer 050g Board of Regulatory Commissioners Hancocks Bridge, NJ 08038 2 Gateway Center, Tenth Floor Newark, NJ 07102 Mr. Louis Storz Sr. Vice President - Nuclear Operations Lower Alloways Creek Township Nuclear Department c/o Mary O. Henderson, Clerk P.O. Box 236 Municipal Building, P.O. Box 157-
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l Hancocks Bridge, NJ 08038 Hancocks Bridge, NJ 08038 L
l' General Manager - Hope Creek Operations Mr. Elbert Simpson Hope Creek Generating Station Senior Vice President.
l P.O. Box 236 Nuclear Engineering Hancocks Bridge, NJ 08038 Nuclear Department P.O. Box 236 Manager-Licensing and Regulation Hancocks Bridge, NJ 08038
- Nuclear Business Unit - N21 l
P.O. Box 236 Hancocks Bridge, NJ 08038 l.
- Regional Administrator, Region I U.S. Nuclear Regulatory Commission L
475 Allendale Road King of Prussia, PA 19406.
Dr. Jill Lipoti, Asst. Director l
Radiation Protection Programs NJ Department of Environmental Protection and Energy CN 415 -
Trenton, NJ 08625-0415 l
- a..
t REQUEST FOR ADDITIONAL INFORMATION FOR RESOLUTION OF GENERIC LETTER 96-06 ISSUES AT THE HOPE CREEK GENERATING STATION 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. Public Service Electric and Gas Company provided its assessment of the waterhammer and two-phase flow issues for the Hope Creek plant in a letter dated January 27,1997. The Hope Creek Emergency Operating Procedures direct operators to use the drywell coolers when high temperatures exist in the drywell following an accident, and the licenses concluded that taking this action could result in a waterhammer undsr certain post-accident conokions. Although the exact magnitude of the waterhammer loads were not determined, the licensee concluded that the affected containment penetrations were not designed for the potential waterhammer loads. As an interim measure to prevent the occurrence of waterhammer, the licensee implemented administrative controls to prohibit the use of the isolation override feature for the drywell cooler water (i.e., chilled water) supply penetrations. Corrective actions being considered by the licensee include:
a). making revisions to the EOPs to address overriding of the containment isolation interlocks of 3
the chilled water system; or I
b) reanalyzing and modifying the affected containment penetrations as necessary to accommodate the waterhammerloads.
Because the drywell coolers do not perform a safety function at the Hope Creek plant, the licensee concluded that the consequential reduction of heat transfer capability of the drywell coolers due to two-phase flow conditions did not pose a problem, and that no further evaluation of the two-phase flow issue was required.
' In order to assess the licensee's resolution of these issues, the following additional information is requested:
- 1. 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 scenados must 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 (if this is a possibility), such that the measures that have been established are adequate to prevent the occurrence of waterhammer during (an:t following) all postulated accident scenarios.
- 2. 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 altemate methodology in detail. Also, explain why this methodology is applicable and gives conservative results for the Hope Creek plant (typically accomplished through rigorous plant-specific modeling, testing, and analysis).
i Note: This question is only applicable to those event scenarios where the occurrence of waterhammer has not been eliminated (see question 1, above)
ENCLOSURE l
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- 3. For both the waterhammer (if applicable as discussed in the note following question 2, above) and the 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 consequences of steam formation, transport, and accumulation; cavitation, resonance, and fatigue effects; and e
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: the three items listed above were not addressed in the licensee's assessment of two-phase flow, and these items are important considerations for assuring that system integrity will be maintained during two-phase flow conditions.)_
- d. 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.
- e. Explain and justify all uses of " engineering judgement."
- 4. Determine the uncertainty in the waterhammer (if applicable as discussed in the note following question 2, above) 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 Hope Creek plant.
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- 5. Confirm that the waterhammer (if applicable as discussed in the note following question 2, above) 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 pedorm its design-basis functions as assumed in the safety analysis report for the facility, and that the containment isolation valves for the affected. system will remain operable.
- 6. 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, u
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