ML17228B537
| ML17228B537 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 06/26/1996 |
| From: | Wiens L NRC (Affiliation Not Assigned) |
| To: | Plunkett T FLORIDA POWER & LIGHT CO. |
| References | |
| GL-95-07, GL-95-7, TAC-M93523, TAC-M93524, NUDOCS 9606280183 | |
| Download: ML17228B537 (5) | |
Text
Mr. Thomas F. Plunke Pr'>sident, Nuclear Di~sion Florida Power and Light Company Post Office Box 14000 Juno
- Beach, Florida 33408-0420 June 26, 1996
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION GENERIC LETTER 95-07, "PRESSURE LOCKING AND THERMAL BINDING OF SAFETY-RELATED POWER-OPERATED GATE VALVES," ST.
LUCIE UNITS 1
AND 2 (TAC NOS.
M93523 AND M93524)
Dear Mr. Plunkett:
On August 17,
- 1995, the NRC issued Generic Letter (GL) 95-07, "Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves," 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.
The NRC staff is reviewing and evaluating your response to GL 95-07.
Additional information, as discussed in the enclosure, is requested in order for the staff to complete its review.
Your response is requested within 30 days of receipt of this letter.
The information requested by this letter is within the scope of the overall burden estimated in Generic Letter 95-07, "Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves," which was a maximum of 75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> per response.
This request is covered by Office of Management and Budget Clearance Number 3150-0011, which expires July 31, 1997.
Sincerely, Original signed by Leonard A. Wiens, Senior Project Manager Project Directorate II-3 Division of Reactor Projects-I/II Office of Nuclear Reactor Regulation Docket Nos.
50-335 and 50-389
Enclosure:
Request for Additional Information cc w/enclosure:
See Distrubution Docket File St.
Lucie Reading J. Zwolinski ACRS R.
Eaton next page PUBLIC S.
Varga OGC D. Verelli, RII H. Rathbun DOCUMENT NAME:
G: gsTLvc!E/sLLTILRAI To receive a copy of this document, indicate ln the boxu C
m Copy without attachment/enclosure E
~ Copy with attachment/enclosure N
~ No copy OFFICE PDII-3/LA PDII-4/PH f>
PDII-3/PD NAME BCIayton L'Miens FHebdon DATE 06/
/96 06/
/96 06 96 OFFICIAL RECORD COPY 9606280i83 960626 PDR ADOCK',05000335 P 'DR
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Mr. T.
F. Plunkett Florida Power and Light Company St. Lucie Plant CC:
Jack Shreve, Public Counsel Office of the Public Counsel c/o The Florida Legislature ill West Madison Avenue, Room 812 Tallahassee, Florida 32399-1400 Senior Resident Inspector St. Lucie Plant U.S. Nuclear Regulatory Commission 7585 S.
Hwy A1A Jensen
- Beach, Florida 34957 Joe Hyers, Director Division of Emergency Preparedness Department of Community Affairs 2740 Centerview Drive Tallahassee, Florida 32399-2100 J.
R.
Newman
- Morgan, Lewis
& Bockius 1800 H Street, N.W.
Washington, DC 20036 John T. Butler, Esquire
- Steel, Hector and Davis 4000 Southeast Financial Center Miami, Florida 33131-2398 Hr. Thomas R.L. Kindred County Administrator St. Lucie County 2300 Virginia Avenue Fort Pierce, Florida 34982 Mr. Charles
- Brinkman, Manager Washington Nuclear Operations ABB Combustion Engineering, Nuclear Power 12300 Twinbrook Parkway, Suite 330 Rockville, Maryland 20852 Hr. Bill Passetti Office of Radiation Control Department of Health and Rehabilitative Services 1317 Winewood Blvd.
Tallahassee, Florida 32399-0700 Regional Administrator, Region II U.S. Nuclear Regulatory Commission 101 Marietta Street, N.W. Suite 2900 Atlanta, Georgia 30323 H. N. Paduano, Manager Licensing 8 Special Programs Florida Power and Light Company P.O.
Box 14000 Juno
- Beach, Florida 33408-0420 J.
A. Stall, Site Vice President St.
Lucie Nuclear Plant P. 0.
Box 128 Ft. Pierce, Florida 34954-0128 J. Scarola Plant General Manager St.
Lucie Nuclear Plant P.O.
Box 128 Ft. Pierce, Florida 34954-0128 Hr. Kerry Landis U.S. Nuclear Regulatory Commission 101 Marietta Street, N.W. Suite 2900 Atlanta, Georgia 30323-0199 E. J.
Weinkam Licensing Manager St.
Lucie Nuclear Plant P.O.
Box 128 Fort Pierce, Florida 34954-0128
0 RE VEST FOR ADDITIONAL INFORMATION ST.
LUCIE UNITS 1
AND 2
RESPONSE
TO GENERIC LETTER 95-07 "PRESSURE LOCKING AND THERMAL BINDING OF SAFETY-RELA ED POWER-OPERATED GATE VALVES" Regarding Unit 1 valves V-1403 and V-1405, Power Operated Relief Valve (PORV) Block Valves, the licensee's submittal states that these valves are 2.5" Velan solid wedge gate valves and discusses previous operating experience in which these valves were used to isolate a leaking PORV when the unit was at IOOX power and subsequently successfully opened for low temperature overpressure (LTOP) protection.
In addition, the licensee's submittal states that these valves have been modified to close on the limit switch.
The staff agrees that (1) past operational experience provides valuable information in determining susceptibility to thermal binding and (2) prevention of excessive closing forces on the valve disk reduces susceptibility to thermal binding.
For the purposes of closure of the NRC staff's GL 95-07 review, does the licensee have diagnostic test data which demonstrates the reduction in closing thrust following the completed modifications to change the seating logic from torque switch to limit switch7 If so, please provide this information for NRC staff review.
2.
Regarding Unit 2 valves V-1476 and V-1477, PORV Block Valves, the licensee's submittal states that these valves are 3" Westinghouse flex-wedge gate valves and discusses the potential susceptibility to pressure locking and thermal binding.
The licensee's submittal states that these valves will receive only steam, which may be a pressure locking concern due to configurations that permit condensate to collect and drain into the valve bonnet with a subsequent temperature increase of the valve bonnet.
- Further, the licensee's submittal states that valves V-1476 and V-1477 are oriented in the "upright" position.
The NRC staff agrees that valves which experience only steam service and are oriented such that steam condensate cannot become trapped in the valve are not susceptible to thermally induced pressure locking.
However, the NRC staff believes that steam will maintain bonnet pressure during an RCS depressurization scenario.
Please address this potential susceptibility to depressurization induced pressure locking.
Has the licensee completed any calculations regarding (1) the thrust required to overcome pressure locking and (2) the actuator capability? If so, please provide these calculations for our review.
Regarding the potential susceptibility of these valves to thermal binding, the licensee's submittal discusses past operational experience and states that the actuators have Limitorque SB operators which have compensating spring packs that absorb inertial closing forces and prevent excessive wedging of the disk into the seat.
Does the licensee have diagnostic test data which demonstrates that the wedging of these valves is not excessive7 If so, please provide this information for our review.
ENCLOSURE
In Attachment I to GL 95-07, the NRC staff requested that licensees include consideration of the potential for gate valves to undergo pressure locking or thermal binding during surveillance testing.
During workshops on GL 95-07 in each
- Region, the NRC staff stated that, if closing a safety-related power-operated gate valve for test or surveillance defeats the capability of the safety system or train, the licensee should perform one of the following within the scope of GL 95-07:
2.
3.
Verify that the valve is not susceptible to pressure locking or thermal binding while closed, Follow plant technical specifications for the train/system while the valve is closed, Demonstrate that the actuator has sufficient capacity to overcome these phenomena, or Hake appropriate hardware and/or procedural modifications to prevent pressure locking and thermal binding.
The staff stated that normally open, safety-related power-operated gate valves which are closed for test or surveillance but must return to the open position should be evaluated within the scope of GL 95-07.
Please discuss if valves which meet this criterion were included in your
- review, and how potential pressure locking or thermal binding concerns were addressed.
Through review of operational experience
- feedback, the staff is aware of instances where licensees have completed design or procedural modifications to preclude pressure locking or thermal binding which may have had an adverse impact on plant safety due to incomplete or incorrect evaluation of the potential effects of these modifications.
Please describe evaluations and training for plant personnel that have been conducted for each design or procedural modification completed to address potential pressure locking or thermal binding concerns.