ML20216B653
| ML20216B653 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 05/11/1998 |
| From: | Skay D NRC (Affiliation Not Assigned) |
| To: | Kingsley O COMMONWEALTH EDISON CO. |
| References | |
| GL-96-06, GL-96-6, TAC-M96825, TAC-M96826, NUDOCS 9805180314 | |
| Download: ML20216B653 (5) | |
Text
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l May 11, 1998
' Mr. Oliver D. Kingsley l
President, Nuclear Generation Group Commonwealth Edison Company Executive Towers West 111 1400 Opus Place, Suite 500 Downers Grove,IL 60515 L
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION -LASALLE STATION, UNITS 1 AND l
2 (TAC NOS, M96825 AND M96826) -
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Dear Mr. Kingsley:
Generic Letter (GL) 96-06, " Assurance of Equipment Operability and Containment Integrity During Design-Basis Accident Conditions," dated September 30,19%, 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. Commonwealth Edison j
Company provided its assessment of the waterhammer and two-phase flow issues for LaSalle, Units 1 and 2, in a letter dated January 28,1997. In order to complete its review, the staff has determined that additional information will be required as discussed in the attachment. We ask that you provide this information by July 30,1998, in order to support our review schedule for GL 96-06.
Should you have any questions, please contact me at (301) 415-1322.
l sincerely, Orig. Signed by S. Richards for Donna M. Skay, Project Manager Project Directorate 111-2 Division of Reactor Projects - lil/IV Office of Nuclear Reactor Regulation Docket Nos. 50-373,50-374
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Reco:"! lor Additional Information 1) cc w/ encl: see next page DISTRIBUTION: Docket.
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9 May 11, 1998 Mr. Oliver D. Kingsley l
President, Nuclear Generation Group Commonwealth Edison Company Executive Towers West lll 1400 Opus Place, Suite 500 l
Downers Grove,IL 60515
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION -LASALLE STATION, UNITS 1 AND 2 (TAC NOS. M96825 AND M96826)
Dear Mr. Kingsley:
Generic Letter (GL) 96-06, " Assurance of Equipment Operability and Containment Integrity During Design-Basis Accident Conditions, dated Septernber 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. Commonwealth Edison Company provided its assessment of the waterhammer and two-phase flow issues for LaSalle, Units 1 and 2, in a letter dated January 28,1997. In order to complete its review, the staff has determined that additionalinformation will be required as discussed in the attachment. We ask that i
you provide this information by July 30,1998, in order to support our review schedule for GL 96-06.
Should you have any questions, please contact me at (301) 415-1322.
l Sincerely, Donna M. Skay, Project Manager Project Directorate ill-2 l
Division of Reactor Projects - lil/IV l
Office of Nuclear Reactor Regulation i
Docket Nos. 50-373, 50-374 l
Enclosure:
Request for Additional Information
{
cc w/ encl: see next page
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O. Kingsley LaSalle County Station Commonwealth Edison Company Units 1 and 2 cc:
Phillip P. Steptoe, Esquire Michael 1. Miller, Esquire Sidley and Austin Sidley and Austin One First National Plaza One First National Plaza Chicago, Illinois 60603 Chicago,lilinois 60603 l
Assistant Attomey General Document Control Desk-Licensing 100 W. Randolph St. Suite 12 Commonwealth Edison Company Chicago, Illinois 60601 1400 Opus Place, Suite 400 Downers Grove, Illinois 60515 U.S. NRC LaSalle Resident inspectors Office 2605 N. 21st Road Commonwealth Edison Company Marseilles, Illinois 61341-9756 Site Vice President - LaSalle 2601 N. 21st Road l
Chairman Marseilles, Illinois 61341-9757 LaSalle County Board of Supervisors l
LaSalle County Courthouse Mr. David Helwig Ottawa, Illinois 61350 Senior Vice President l
Commonwealth Edison Company l
Attomey General Executive Towers West 111 l
500 S. Second Street 1400 Opus Place, Suite 900 Springfield, Illinois 62701 Downers Grove, IL 60515 Chairman Mr. Gene H. Stanley lilinois Commerce Commission PWR's Vice President 527 E. Capitol Avenue, Leland Building Commonwealth Edison Company Springfield, Illinois 62706 Executive Towers West lll 1400 Opus Place, Suite 900 lilinois Department of Nuclear Safety Downers Grove,IL 60515 Office of Nuclear Facility Safety 1035 Outer Park Drive Mr. Steve Peny Springfield, Illinois 62704 BWR's Vice President l
Commonwealth Edison Company Regional Administrator Executive Towers West 111 U.S. NRC, Region lil 1400 Opus Place, Suite 900 801 Warrenville Road Downers Grove,IL 60515 Lisle, lilinois 60532-4351 Mr. Dennis Farrar Commonwealth Edison Company Regulatory Services Manager i
LaSalle Station Manager Commonwealth Edison Company 2601 N. 21st Road Executive Towers West ll1 Marseilles, Illinois 61341-9757 1400 Opus Place, Suite 500 Downers Grove, IL 60515 Robert Cushing, Chief, Public Utilities Division lilinois Attomey General's Office 100 W. Rsndolph Street Chicago, Illinois 60601
'~~
O. Kingsley LaSalle County Station Commonwealth Edison Company Units 1 and 2 Ms. Irene Johnson, Licensing Director Nuclear Regulatory Services Commonwealth Edison Company Executive Towers West til 1400 Opus Place, Suite 500 Downers Grove, IL 60515 Commonwealth Edison Company Reg. Assurance Supervisor-LaSalle 2601 N. 21st Road Marseilles, Illinois 61341-9757 Mr. Michael J. Wallace Senior Vice President Commonwealth Edison Company Executive Towers West lli 1400 Opus Place, Suite 900 Downers Grove,IL 60515 t
i,
REQUEST FOR ADDITIONAL INFORMATION FOR RESOLUTION OF l
GL 96-06 ISSUES AT LASALLE 1 & 2 1.
Describe measures that have been taken to assure that plant operators will not use the containment /drywell coolers as an option during accident conditions.
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 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 j
to prevent the occurrence of waterhammer during (and following) all postulated accident scenarios.
3.
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 (typically accomplished through rigorous plant specific modeling, testing, and analysis).
Note: This question is only applicable to those event scenarios where the occurrence of waterhammer has not been eliminated (see question 2, above).
4.
For both the waterhammer (if applicable as discussed in the note following question 3, 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 benchmark the codes for the specific loading conditions involved (see Standard Review Plan Section 3.9.1).
l l
b.
Describe and justify all assumptions and input parameters (including those used in l
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 l
omitting any effects that may be relevant to the analysis (e.g., fluid structure l
interaction, flow induced vibration, erosion),
t 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; the consequences of steam formation, transport, and accumulation; a
ENCLOSURE
'o cavitation, resonance, and fatigue effects; and a
erosion considerations.
=
Licensees may find NUREG/CR-6031, " Cavitation Guide for Control Valves,"
helpfulin addressing some aspects of the two-phase flow analyses. (Note: it is important for licensets to realize thatin addition to heat transfer considerations, two-phase flow also involves structural and system integrity concems that must be addressed).
d.
Confirm that the wawthammer und two-phase flow analyses included a complete failure modes and effects analyses (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".
l 5.
Determine the uncertainty in the waterhammer (if applicable as discussed in the note following question 3, 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.
6.
Confirm that the waterhammer (if applicable as discussed in the note following question 3, 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 perform its design-basis functions as assumed in the safety analysis report for the facility, and that the containment isolation valves will remain operable.
7.
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.
8.
Describe in catail any modifications that have been made or are planned to resolve the waterhammer and two-phase flow issues discussed in GL 96-06.