ML20211N804
| ML20211N804 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 09/08/1999 |
| From: | Padovan L NRC (Affiliation Not Assigned) |
| To: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| References | |
| GL-96-06, TAC-M96809, TAC-M96810, NUDOCS 9909130076 | |
| Download: ML20211N804 (4) | |
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September 8, 1999 Mr. D. N. Morey Vice President - Farley Project Southern Nuclear Operating Company, Inc.
Post Office Box 1295 Birmingham, Alabama 35201-1295
SUBJECT:
JOSEPH M. FARLEY NUCLEAR PLANT, UNITS 1 AND 2 RE: GENERIC LETTER 96-06 CLOSEOUT (TAC NOS. M96809 AND M96810)
Dear Mr. Morey:
On September 30,1996, the U.S. Nuclear Regulctory Commission (NRC) issued Generic Letter (GL) 96-06 " Assurance of Equipment Operability and Containment Integrity During Design-Basis Accident Conditions" to holders of nuclear plant operating licenses. The GL requested licensees to evaluate their nuclear plant cooling water systems that serve containment air coolers to assure that the systems are not vulnerable to the following:
waterhammer and two-phase flow conditions a
thermally-induced piping overpressurization a
You responded to GL 96-06 for the Farley Nuclear Plant, Units 1 and 2, in your letters of January 27, and May 23,1997. You submitted additional information in your letters of June 29, October 1, and October 30,1998. We also had clarifying telephone discussions with Southern Nuclear Operating Company (SNC) personnel on October 8,1998, and on September 22,1998. Our waterhammer and two-phase flow condition evaluations of your submittals follow.
Waterhammer and Two-Phase Flow Evaluation You indicated that SNC had previously addressed the GL 96-06 waterhammer concerns in response to NRC Region il inspection findings. Region 11 originally documented the issue in an inspection report as Unresolved item 93-13-02. Region 11 later reviewed and accepted how SNC resolved this issue, as documented in Inspection Report 94-21 on September 29,1994.
We confirmed that your 1993 waterhammer analysis included heat transfer and single-active failure considerations so that your analysis bounded the worst-case scenario. Also, we assessed Farley's service water system design, especially with regard to static pressure considerations, to assure that two-phase flow conditions would not develop. We are satisfied with your response, and because Region 11 inspectors previously reviewed the waterhammer issue, we consider the waterhammer and two-phase flow elements of GL 96-06 to be closed for Farley Nuclear Plant, Units 1 and 2.
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Thermally-Induced Pressurization Evaluation
,Your submittals of January 28, and May 23,1997, identified eight penetrations potentially susceptible to thermally-induced pressurization. Your near-term review determined that all
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t D. N. Morey eight penetrations were operable, but that you would have to take some long-term corrective actions. Your long-term actions consisted of (1) installing relief valves on two penetrations to relieve thermal overpressure, and (2) keeping certain system valves open to relieve thermal overpressure on two other penetrations. SNC calculated pioing pressure for two penetrations based on a heat transfer analysis and determined the pressure for two other penetrations based on the pressure required to lift isolation valves off their seats.
Our August 25,1998, letter requested additional information about your analysis methodology and results for the four penetrations where you based pressurization on heat transfer or valve lift-off pressure. Your October 10,1998, submittal provided the requested analysis methodology and results for these four penetrations. Based on our review of your methodology, we find that the calculation of the resulting pressures in these penetrations is conservative for the elevated temperature post-accident conditions. We note that you did not combine the pressurization stresses with other faulted events (i.e., seismic), as would normally be done, since you judged that the faulted events would occur for only a relatively short duration. We also note that your method for determining the pressurization is conservative in that you determined the pipe stresses clastically and assumed instantaneous heat transfer into the pipe segments. In addition, the analyzed stresses are significantly less than American Society of Mechanical Engineers Code faulted allowable stresses. Therefore, the staff determined that your evaluation for these penetrations is acceptable.
In summary, the staff concludes that your evaluations and corrective actions acceptably resolve the GL 96-06 issue for the Farley Nuclear Plant, Units 1 and 2. Please call me at (301) 415-1423 if you have any questions, j
l Sincerely, O$w-j L. Mark Padovan, Project Manager, Section 1 Project Directorate 11 Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-348 and 50-364 cc: See next page
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Joseph M. Farley Nuclear Plant cc:
Mr. L. M. Stinson Rebecca V. Badham
. General Manager -
SAEH Supervisor Southern Nuclear Operating Company Southern Nuclear Operating Company
' Post Office Box 470 -
P. O. Box 470 Ashford, Alabama 36312 Ashford, Alabama 36312 Mr. Mark Ajtuni, Licensing Manager Southern Nuclear Operating Company Post Office Box 1295'
. Birmingham, Alabama 35201-1295 Mr. M. Stanford Blanton Balch and Bingham Law Firm Post Office Box 306 1710 Sixth Avenue North Birmingham, Alabama 35201 Mr. J. D. Woodard Executive Vice President Southern Nuclear Operating Company Post Office Box 1295 Birmingham, Alabama 35201
. State Health Officer Alabama Department of Public Health 434 Monroe Street l
Montgomery, Alabama 36130-1701 Chairman
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Houston County Commission j
Post Office Box 6406 Dothan, Alabama 36302 Resident inspector U.S. Nuclear Regulatory Commission 7388 N. State Highway 95 Columbia, Alabama 36319 l
D Q. Morey eight penetrations were operable, but that you would have to take some long-term corrective actions. Your long-term actions consisted of (1) installing relief valves on two penetrations to relieve thermal overpressure, and (2) keeping certain system valves open to relieve thermal overpressure on two other penetrations. SNC calculated piping pressure for two penetrations based on a heat transfer analysis and determined the pressure for two other penetrations based on the pressure required to lift isolation valves off their seats.
Our August 25,1998, letter requested additional information about your analysis methodology and results for the four penetrations where you based pressurization on heat transfer or valve lift-off pressure. Your October 10,1998, submittal provided the requested analysis methodology and results for these four penetrations. Based on our review of your methodology, we find that the calculation of the resulting pressures in these penetrations is conservative for the elevated temperature post-accident conditions. We note that you did not combine the pressurization stresses with other faulted events (i.e., seismic), as would normally be done, since you judged that the faulted events would occur for only a relatively short duration. We also note that your method for determining the pressurization is conservative in that you determined the pipe stresses elastically and assumed instantaneous heat transfer into the pipe segments. In addition, the analyzed stresses are significantly less than American Society of Mechanical Engineers Code faulted allowable stresses. Therefore, the staff determined that your evaluation for these penetrations is acceptable.
In summary, the staff concludes that your evaluations and corrective actions acceptably resolve the GL 96-06 issue for the Farley Nuclear Plant, Units 1 and 2. Please call me at (301) 415-1423 if you have any questions.
j Sincerely, t
Original signed by:
L. Mark Padovan, Project Manager, Section 1 Project Directorate 11 Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-348 and 50-364 cc: See next page DISTRIBUTION:
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