ML17313A974
| ML17313A974 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 06/11/1999 |
| From: | Fields M NRC (Affiliation Not Assigned) |
| To: | James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| References | |
| TAC-M93497, TAC-M93498, TAC-M93499, NUDOCS 9906150132 | |
| Download: ML17313A974 (12) | |
Text
Mr. James M. Levine Senior Vice President, Nuclear Arizona Public Service Company P. O. Box 53999 Phpenix, AZ 85072-3999 3une 11, 1999
SUBJECT:
PALO VERDE NUCLEAR GENERATING STATION - REQUEST FOR ADDITIONALINFORMATIONON GENERIC LETTER 95-07, "PRESSURE LOCKINGAND THERMALBINDINGOF SAFETY-RELATED POWER-OPERATED GATE VALVES(TAC NOS. M93497, M93498, AND M93499)
Dear Mr. Levine:
On August 17, 1995, the NRC issued Generic Letter (GL) 95-07 to request that licensees take actions to ensure that safety-related power-operated gate valves that are susceptible to pressure locking or thermal binding are capable of performing their safety functions.
By letter dated February 21, 1996, Arizona Public Service Company (APS) submitted its 180-day response to GL 95-07 for the Palo Verde Nuclear Generating Station and supplemented this response in a letter dated June 28, 1996. The NRC staff reviewed APS'nitial submittal and requested additional information in a letter dated June 27, 1996.
In a letter of August 6, 1996, APS provided the requested information. The staff has reviewed the latest APS submittal and has determined that additional information is necessary to complete its review.
The enclosed request for additional information was discussed with your staff on May 20, 1999, and a mutually agreeable target date of within 120 days of the date of this letter for your response was established.
Ifcircumstances result in the need to revise the target date, please call me at the earliest opportunity.
Ifyou have any questions, please contact me at (301) 415-3062.
9906i50132 79061K PDR ADQCK 05000528 P
>DR Docket Nos. STN 50-528, STN 50-529 and STN 50-530 Sincerely,
/s/
Mel B. Fields, Project Manager, Section 2 Project Directorate IV8 Decommissioning
'ivision of Licensing Project Management Office of Nuclear Reactor Regulation
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Mr. James M. Levine Senior Vice President, Nuclear Arizona Public Service Company P. O. Box 53999 Phoenix, AZ 85072-3999 UNITED STATES NUCLEAR REGULATOR'Y C OMMISSION WASHINGTON> D.C. 20555-0001 dune 11, 1999
Dear Mr. Levine:
SUBJECT:
PALO VERDE NUCLEAR GENERATING STATION - REQUEST FOR ADDITIONALINFORMATIONON GENERIC LETTER 95-07, "PRESSURE LOCKINGANDTHERMALBINDINGOF SAFETY-RELATEDPOWER-OPERATED GATE VALVES(TAC NOS. M93497, M93498, AND M93499)
On August 17, 1995, the NRC issued Generic Letter (GL) 95-07 to request that licensees take actions to ensure that safety-related power-operated gate valves that are susceptible to pressure locking or thermal binding are capable of performing their safety functions.
By letter dated February 21, 1996, Arizona Public Service Company (APS) submitted its 180-day response to GL 95-07 for the Palo Verde Nuclear Generating Station and supplemented this response in a letter dated June 28, 1996. The NRC staff reviewed APS'nitial submittal and requested additional information in a letter dated June 27, 1996.
In a letter of August 6, 1996, APS provided the requested information. The staff has reviewed the latest APS submittal and has determined that additional information is necessary to complete its review.
The enclosed request for additional information was discussed with your staff on May 20, 1999, and a mutually agreeable target date of within 120 days of the date of this letter for your response was established.
Ifcircumstances result in the need to revise the target date, please call me at the earliest opportunity.
Ifyou have any questions, please contact me at (301) 415-3062.
Sincerely, Docket Nos. STN 50-528, STN 50-529 and STN 50-530
Enclosure:
As stated cc w/encl: See next page Mel B. Fields, Project Manager, Section 2 Project Directorate IV 8 Decommissioning Division of Licensing Project Management Office of Nuclear Reactor Regulation
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Pqlo Verde Generating Station, Units 1, 2, and 3 CC:
Mr. Steve Olea Arizona Corporation Commission 1200 W. Washington Street Phoenix, AZ 85007 Douglas Kent Porter Senior Counsel Southern California Edison Company Law Department, Generation Resources P.O. Box 800
- Rosemead, CA 91770 Senior Resident Inspector U.S. Nuclear Regulatory Commission P. O. Box 40 Buckeye, AZ 85326 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Harris Tower & Pavillion 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 Chairman, Board of Supervisors ATTN: Chairman 301 W. Jefferson, 10th Floor Phoenix, AZ 85003 Mr. David Summers Public Service Company of New Mexico 414 Silver SW, ¹1206 Albuquerque, NM,87102 Mr. Jarlath Curran Southern California Edison Company 5000 Pacific Coast Hwy Bldg DIN San Clemente, CA 92672 Mr. Robert Henry Salt River Project 6504 East Thomas Road Scottsdale, AZ 85251 Terry Bassham, Esq.
General Counsel El Paso Electric Company 123 W. Mills El Paso, TX 79901 Mr. John Schumann Los Angeles Department of Water & Power Southern California Public Power Authority P.O. Box 51111, Room 1255-C Los Angeles, CA 90051 Mr. Aubrey V. Godwin, Director Arizona Radiation Regulatory Agency 4814 South 40 Street Phoenix, AZ 85040 Ms. Angela K. Krainik, Manager Nuclear Licensing Arizona Public Service Company P.O. Box 52034 Phoenix, AZ 85072-2034 Mr. John C. Home Vice President, Power Generation El Paso Electric Company 2702 N. Third Street, Suite 3040 Phoenix, AZ 85004 May19,1999
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RE VEST FOR ADDITIONALINFORMATION "PRESSURE LOCKINGANDTHERMALBINDINGOF SAFETY-RELATED POWER-OPERATED GATE VALVES" GENERIC LE%I'ER 95-07 ARIZONAPUBLIC SERVICE COMPANY PALO VERDE NUCLEAR GENERATING STATION UNITS 1 2 AND 3 DOCKET NOS. STN 50-528 STN 50-529 AND STN 50-530 1.
In the February 21, 1996, response to Generic Letter (GL) 95-07 it states that you used a pressure locking thrust prediction methodology to calculate the opening stem thrust required to overcome pressure locking. This analytical method was used as a long-term corrective action to demonstrate the valves would operate during pressure locking conditions. GL 95-07 states that the use of a pressure locking thrust prediction methodology is an acceptable corrective action to demonstrate that valves are capable of operating during pressure locking conditions provided that the methodology is validated by a test program.
During a phone call conducted on May 20, 1999, you stated that your pressure locking thrust prediction methodology was based on assumptions similar to the assumptions used in the pressure locking thrust prediction methodology developed by Entergy Operations, Inc. (EOI).
On March 25, 1997, EOI submitted to the NRC staff the test results that were used to validate its pressure locking thrust prediction methodology.
On April 9, 1997, a public meeting was conducted to discuss the EOI pressure locking thrust prediction methodology presented in its GL 95-07 submittals.
The minutes of the public meeting were issued on April25, 1997, and placed in the Public Document Room. The EOI methodology that predicts the thrust required to open pressure-locked flexible-wedge gate valves, validation testing of the analytical method, and pressure locking tests sponsored by the NRC conducted by Idaho National Engineering and Environmental Laboratory (INEEL)were discussed during the meeting.
The minutes of this public meeting indicate the type of information requested by the NRC in order to review and approve a pressure locking thrust prediction methodology.
Atthe conclusion of the meeting, the NRC staff identified several unresolved items associated with the EOI test program in supporting its pressure locking thrust prediction methodology.
In a letter dated June 30, 1997, EOI stated that more testing would be performed to validate its pressure locking thrust prediction methodology.
In a letter dated May 4, 1999 (Accession Number 9905120112), EOI submitted the results of these additional tests.
EOI concluded that when used in accordance with application guidelines, its pressure locking thrust prediction methodology conservatively estimates the thrust required for valves to operate during pressure locking conditions. The NRC staff is reviewing the EOI pressure locking thrust prediction methodology.
In order for the NRC to review your pressure locking thrust prediction methodology, please provide the following information:
ENCLOSURE
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Describe the pressure locking thrust prediction methodology and provide the test procedure/results that validated the methodology.
Include any information that will help evaluate ifyour valves are similar to test valves as applicable.
b.
Results from pressure locking testing sponsored by the NRC performed by INEEL on a flexible wedge gate valve have been placed in the Public Document Room (NUREG/CR-6611, "Results of Pressure Locking and Thermal Binding Tests of Gate Valves"). Discuss ifyour pressure locking thrust prediction methodology accurately calculates the results of these pressure locking tests.
Discuss the recommended margin between actuator capability and the calculated thrust value when using your pressure locking thrust prediction methodology, any limitations associated with the use of your methodology and any diagnostic test equipment accuracy requirements.
Commonwealth Edison provided this type of information to the NRC in a letter dated May 29, 1998. This letter is in the Public Document Room (Accession Number. 9806040184).
Pressure locking test results conducted by INEEL on a flexible wedge gate valve discussed in NUREG/CR-6611 indicated that, as differential pressure between the bonnet and the downstream (or upstream) side of the valve increased, the stem thrust required to open the pressure-locked valve increases.
The EOI pressure locking methodology predicted that the opposite would occur in that, as differential pressure between the bonnet and downstream (or upstream) side of the valve increased, the stem thrust predicted to open the pressure-locked valve decreased.
Discuss how your pressure locking thrust prediction methodology trends as differential pressure between the bonnet and the downstream (or upstream) side of the valve increases.
If applicable, discuss any differential pressure restrictions or other conditions associated with the'use of your pressure locking thrust prediction methodology.
Identify the valves for which your pressure locking thrust prediction methodology was used to demonstrate that the valves would operate during pressure locking conditions.
2.
The February 21, 1996, submittal states that an algorithm was used to calculate thermally induced bonnet pressure increase in determining the maximum bonnet pressure in your pressure locking thrust prediction methodology.
Describe the algorithm and the basis for the algorithm.
b.
Discuss ifyour algorithm accurately predicted the pressure/temperature relationship test results sponsored by the NRC and conducted by INEELthat are documented in NUREG/CR-6111.
Testing conducted by INEEL identified thermal-induced pressurization rates of up to 50 psi/'F.
Assuming zero leakage through the valve seats and stem packing, zero entrapped air and negligible pressure expansion of the valve bonnet, the theoretical increase in bonnet pressure due to temperature increase is greater than 50 psi/'F.
Ifthe results of your algorithm are less conservative than the INEEL pressurize/temperature relationship test results, explain why it is acceptable to use the results of your algorithm.
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The February 21, 1996, submittal states that thermal binding test results from a 10-inch Borg Warner valve were used to determine the additional thrust required for valves to operate during thermal binding conditions.
During a phone call conducted on May 20, 1999, you stated that there are no solid wedge gate valves in the scope of GL 95-07 and that flexible wedge gate valves in the scope of GL 95-07 were evaluated for thermal binding.
The NRC staff considers that thermal binding occurs as a result of valve design characteristics such as wedge and valve body configuration, flexibility(pressure rating),
and material thermal coefficients. The NRC staff has approved the use of thermal binding test results to demonstrate that valves willoperate during thermal binding conditions as acceptable corrective action for GL 95-07.
However, the thermal binding test results were used for valves with very similar design characteristics.
a.
Identify the instances where the test results from the Borg Warner valve were used to determine that valves are capable of operating during thermal binding conditions.
b.
Discuss the Borg Warner thermal binding test results that were used in determining if valves were susceptible to thermal binding.
c.
Discuss the valve design characteristics (wedge and valve body configuration, flexibility(pressure rating), and material thermal coefficients) of the Borg Warner test valve and the valves that utilized the Borg Warner valve test results to demonstrate that the valves would operate during thermal binding conditions.
d.
Ifthe design characteristics are not similar, discuss long-term corrective action, and any short-term corrective action, ifapplicable, to ensure valves susceptible to thermal binding are operable.
4.
Brieflyexplain the modifications that have been implemented or are scheduled to be implemented to eliminate the potential for pressure locking. Ifthe modification involves the installation of a bonnet relief valve, discuss relief valve setpoint and how it is verified that the valve willopen when pressure in the bonnet is higher than upstream and downstream pressure but below the relief valve setpoint.
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