ML18152B424
| ML18152B424 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 05/25/1999 |
| From: | Edison G NRC (Affiliation Not Assigned) |
| To: | Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| GL-95-07, GL-95-7, TAC-M93526, TAC-M93527, NUDOCS 9906070161 | |
| Download: ML18152B424 (5) | |
Text
~-**
e May 25, 1999 e
- *Mr. J. P. O'Hanlon Senior Vice President - Nuclear Virginia Electric and Power Company 5000 Dominion Blvd.
Glen Allen, Virginia 23060
SUBJECT:
SURRY UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION CONCERNING GENERIC LETTER 95-07, PRESSURE LOCKING AND THERMAL BINDING OF VALVES (TAC NOS. M93526 AND M93527)
Dear Mr. O'Hanlon:
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.
In a letter of February 7, 1996, Virginia Electric and Power Company submitted its 180-day response to GL 95-07 for Surry Power Station, Units 1 and 2. The NRC staff reviewed your 180-day response and requested additional information in a letter dated June 6, 1996. In your letter of July 3, 1996, you provided the additional information.
We have reviewed your response and determined that additional information is necessary to complete our safety evaluation. On May 6, 1999, the enclosed questions were discussed with Mr. Tom Shaub and other members of your staff during a telephone conversation. A target date of August 16, 1999, was agreed upon for your response. If circumstances result in the need to revise the target date, please contact me at the earliest opportunity.
Sincerely,.
original signed by:
Gordon Edison, Senior Project Manager, Section 1 Project Directorate II
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PDR ADOCK 05000280 p
f'DR Division of Licensing Project Management i
Office of Nuclear Reactor Regulation I.
Docket Nos. 50-280 and 50-281
Enclosure:
As stated cc: See next page Distribution:
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e UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555--0001 May 25, 1999
SUBJECT:
SURRY UNITS 1 AND 2 ** REQUEST FOR ADDITIONAL INFORMATION CONCERNING GENERIC LCTTER 95-07, PRESSURE LOCKING AND THERMAL BINDING OF VALVES (TAC NOS. M93526 AND M93527)
Dear Mr. O'Hanlon:
On August 17, 1995, the NRC issued Generic Letter (GL) 95-07, "Pressure Locking and Thermal E3inding 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.
In a letter of February 7, 1996, Virginia Electric and Power Company submitted its 180-day response to GL 9"5-07 for Surry Power Station, Units 1 and 2. The NRC staff reviewed your.
, 180-day response ancf requested additional information in a letter dated June 6, 1996. In your letter of July 3, 1996, you provided the additional information.
We have reviewed your response and determined that additional information is necessary to complete our safety evaluation, On May 6, 1999, the enclosed questions were discussed with Mr. Tom Shaub and other members of your staff during a telephone conversation. A target date of August 16, 1999, was agreed upon for your response. If circumstances result in the need to revise the target date, please contact me at the earliest opportunity.
Docket Nos. 50-280 and 50-281
Enclosure:
As stated cc: See next page Sincerely, Gordon Edison, Senior Project Manager, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation
-- -. **----- ****---*,***---*-----*------*-----------.--------.................. -.~"...... _.,.....,_, ___ ~------ ----------*-f"**.--**----.-----**-------*-,,*--------- ------ -
Mr. J. P. O'Hanlon Virginia Electric and Power Compariy cc:
- Mr. Donald P. Irwin, Esq.
Hunton and Williams Riverfront Plaza, East Tower 951 E. Byrd Street Richmond, Virginia 23219
. Mr. E. S. Grecheck Site Vice President Surry Power Station Virginia Electric and Power Company 5570 Hog Island Road Surry, Virginia 23883 Senior Resident Inspector Surry Power Station U. S. Nuclear Regulatory Commission 5850 Hog Island Road Surry, Virginia 23883 Chairman Board of Supervisors of Surry County
- Surry County Courthouse Surry, Virginia 23683 Dr. W. T. Lough Virginia State Corporation Commission Division of Energy Regulation P. 0. Box 1197 Richmond, Virginia 23209 Robert B. Strobe, M.D., M.P.H.
State Health Commissioner Office of the Commissioner Virginia Department of Health P.O. Box 2448 Richmond, Virginia 23218 e
Surry Power Station Office of the Attorney General Commonwealth of Virginia 900 East Main Street Richmond, Virginia 23219 Mr*. J. H. McCarthy, Manager Nucle;;\\r Licensing & Operations Support Innsbrook Technical Center Virginia Electric and Power Company 5000 Dominion Blvd.
Glen Allen, Virginia 23060 Mr. W. R. Matthews
- Site Vice President North Anna Power Station Virginia Electric and Power Company P.O. Box402 Mineral, Virginia 23117
e e
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SECOND REQUEST FOR ADDITIONAL INFORMATION SURRY POWER STATION RESPONSE TO GENERIC LEITER 95-07, "PRESSURE LOCKING AND THERMAL BINDING
- OF SAFETY-RELATED POWER-OPERATED GATE VALVES"
- 1. During a postulated accident, the containment would be initially pressurized to a peak
. pressure and the bonnets of the low head safety injection (LHSI) pu,r;p containment sump isolation valves, 1 (2)-SI-MOV-1 (2)860A/B, could also be pressurized to Go.ntainment peak pressure.
- When transferring to the redrculation phase of a postulated accident, containment
- pressure could be lower than the initial peak pressure but the pressure in the bonnets of
_ 1 (2)-Sl-r,,10V-1 (2)860A/B could still be at containment peak pressure. Discuss if the pressure in the bonnets of the valves could be higher than upstream and downstream pressure due to changes in containment pressure when the valves are required to open and, if applicable, if the valves will open during this pressure locking condition.
- 2. Your submittal dated July 3, 1996, stated that calculations were used to demonstrate that the
. high head ~afety injection (HHSI) pump discharge to alternate reactor coolant system (RCS) cold leg v~lves, 1 (2)-SI-MOV-1 (2)842, and the HHSI pump discharge to RCS hot leg valves, 1(2)-S1-MOV-1(2)869A/B, would operate during press,ure locking conditions. Verify that these are flexible wedge gate valves and that the temperature of the valves does not increase during the recirculation phase of the accident.
- 3. Your submittal dated July 3, 1996, _states that the pressurizer power-operated relief valve (PORV) block.valves, '.1 (2)-RC-MOV-1 (2)535/536, are not a pressure locking concern because the valves' bonnets are filled with steam. These valves are a pressure locking concern at other Westinghouse plants for steam generator tube rupture events. These pressure locking evaluations assume 2235 psig in the bonnet of the valves (parallel disk or flexible wedge gate valves and steam or water in the valve bonnet) and an RCS pressure of approximately 1400-1500 psig. As a result, the valves are modified or a calculation is used to demonstrate that the
- valves will operate during this pressure locking scenario. Explain why pressure locking is not a concern for the pressurizer PORV block valves at Surry.
- 4. In Attachment 1 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. Valve stroke time testing is considered a surveillance test. During workshops on GL 95-07 in each Region, the NRC staff stated that the licensee should perform one of the following actions within the scope of GL 95-07 if closing a safety-related power-operated gate valve for test or surveillance defeats the capability of the safety system or train:
- a.
Verify that the valve is not susceptible to pressure locking or thermal binding while closed,
- b.
Follow plant technical specifications for the train/system while the valve is closed,
C.
- d.
e Demonstrate that the actuator has sufficient capacity to overcome these phenomena, or Make appropriate hardware and/or procedural modifications to prevent pressure locking and thermal binding.
Verify that normally open, safety-related power-operated gate valves, whlch are closed for surveillance but must return to the open position, were evaluated in :1ccordance with one of these criteria.