ML14183A856
| ML14183A856 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 04/24/1998 |
| From: | James Shea Office of Nuclear Reactor Regulation |
| To: | Keenan J Carolina Power & Light Co |
| References | |
| GL-96-006, TAC-M96859 NUDOCS 9805010184 | |
| Download: ML14183A856 (4) | |
Text
April 24, 1998
- Mr. J. S. Keenan, Vice Pr dent Carolina Power & Light Company H. B. Robinson Steam Electric Plant, Unit No. 2 3581 West Entrance Road Hartsville, South Carolina 29550
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION; GENERIC LETTER 96-06, "ASSURANCE OF EQUIPMENT OPERABILITY AND CONTAINMENT INTEGRITY DURING DESIGN BASIS ACCIDENT CONDITIONS," H. B. ROBINSON, UNIT 2 (TAC NO. M96859)
Dear Mr. Keenan:
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. Carolina Power and Light Company provided its assessment of the waterhammer and two-phase flow issues for H.B. Robinson, Unit 2, in a letter dated January 28, 1997. In order to complete our review of your resolution of these issues, we will require additional information as discussed in the Enclosure. We request that you provide this information by June 30, 1998, in order to support our review schedule for GL 96-06.
If you should have any questions regarding this request, please contact me at (301) 415-1428.
Sincerely, (Original Signed By)
Joseph W. Shea, Project Manager Project Directorate 11-1 Division of Reactor Projects - 1/11 Office of Nuclear Reactor Regulation Docket No. 50-261
Enclosure:
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Mr. J. S. Keenan H. B. Robinson Steam Electric Carolina Power & Light Company Plant, Unit No. 2 cc:
Mr. William D. Johnson Mr. Mel Fry, Acting Director Vice President and Senior Counsel N.C. Department of Environment, Carolina Power & Light Company Health and Natural Resources Post Office Box 1551 Division of Radiation Protection Raleigh, North Carolina 27602 3825 Barrett Dr.
Raleigh, North Carolina 27609-7721 Ms. Karen E. Long Assistant Attorney General Mr. Robert P. Gruber State of North Carolina
- Executive Director Post Office Box 629 Public Staff - NCUC Raleigh, North Carolina 27602 Post Office Box 29520 Raleigh, North Carolina 27626-0520 U.S. Nuclear Regulatory Commission Resident Inspector's Office Mr. Max Batavia, Chief H. B. Robinson Steam Electric Plant South Carolina Department of Health 2112 Old Camden Road Bureau of Radiological Health Hartsville, South Carolina 29550 and Environmental Control 2600 Bull Street Regional Administrator, Region II Columbia, South Carolina 29201 U.S. Nuclear Regulatory Commission Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85 Ms. D. B. Alexander Atlanta, Georgia 30303 Manager Performance Evaluation and Mr. J. W. Moyer Regulatory Affairs Plant General Manager Carolina Power & Light Company Carolina Power & Light Company 412 S. Wilmington Street H. B. Robinson Steam Electric Plant Raleigh, North Carolina 27601 Unit No. 2 3581 West Entrance Road Hartsville, South Carolina 29550 Mr. Milton Shymlock U. S. Nuclear Regulatory Commission Public Service Commission Atlanta Federal Center State of South Carolina 61 Forsyth St., SW, Suite 23T85 Post Office Drawer 11649 Atlanta, Georgia 30303 Columbia, South Carolina 29211 Mr. T. M. Wilkerson Manager - Regulatory Affairs Mr. H. K. Chernoff Carolina Power & Light Company Supervisor, Licensing/Regulatory Programs H. B. Robinson Steam Electric Plant, Carolina Power & Light Company Unit No. 2 H. B. Robinson Steam Electric Plant, 3581 West Entrance Road Unit No. 2 Hartsville, South Carolina 29550-0790 3581 West Entrance Road Hartsville, South Carolina 29550
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REQUEST FOR ADDITIONAL INFORMATION (RAI)
GENERIC LETTER 96-06, "ASSURANCE OF EQUIPMENT OPERABILITY AND CONTAINMENT INTEGRITY DURING DESIGN BASIS ACCIDENT CONDITIONS" 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. Carolina Power and Light Company (the licensee) provided its assessment of the waterhammer and two-phase flow issues for H.B. Robinson, Unit 2, in a letter dated January 28, 1997. The licensee's response indicates that the loss-of-power (LOP) scenario bounds the loss-of-coolant accident (LOCA)/LOP scenario, and simulated LOP events that have been induced during each refueling outage demonstrate that service water piping and supports are capable of withstanding the waterhammer loads. The licensee's response also indicates that containment heat removal will not be degraded below what has been credited in the accident analysis by the two-phase flow conditions that could exist downstream of the throttle valves for the containment air coolers. In order to assess the licensee's resolution of these 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 alternate methodology in detail. Also, explain why this methodology is applicable and gives conservative results for H.B. Robinson, Unit 2 (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 benchmark 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:
Enclosure
-2 the effects of void fraction on flow balance and heat transfer; 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: while the four items listed above are important considerations for evaluating two-phase flow conditions, the last three were not addressed in the licensee's responsey.
- d. Confirm that the 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 judgment."
- 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 H.B. Robinson plant.
- 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 will continue to perform its design-basis functions as assumed in the safety analysis report for the facility.
- 5.
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.
- 6.
Provide a list of penetrations that are protected by relief valves. Identify the system and specifiy the pipe size for each penetration listed.