ML20207H372

Informs That Attached Draft Request for Addl Info Re GL 95-07, Pressure Locking & Thermal Binding, Was Transmitted by Facsimile to G Busch of Gpu Nuclear to Be Discussed in Conference Call Scheduled for 990614

ML20207H372
Person / Time
Site:	Oyster Creek
Issue date:	06/10/1999
From:	Pastis H NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
GL-95-07, GL-95-7, TAC-M93495, NUDOCS 9906160184
Download: ML20207H372 (4)

Text

.. n June 10,1999 MEMORANDUM TO: Docket File FROM: Helen N. Pastis, Senior Project Manager, Section 2 Original signed by:

Project Directorate i Division of Licensing Project Management Office of Nuclear Reactor Regulation

SUBJECT:

OYSTER CREEK- DRAFT REQUEST FOR ADDITIONAL INFORMATION REGARDING GENERIC LETTER 95-07, " PRESSURE LOCKING AND THERMAL BINDING"(TAC NO. M93495)

The attached draft request for additional information (RAl) was transmitted by facsimile to George Busch of GPU Nuclear to be discussed in a conference call scheduled for June N, 1999. Review of the RAI would allow the licensee to clarify their understanding of the NRC staff's questions and agree upon a schedule to respond to the RAI. This memorandum and the attachment do not convey a formal request for information or represent an NRC staff position.

Docket No. 50-219

Attachment:

As stated DISTRIBUTION Docket File PUBLIC '

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OFFICIAL RECORD COPY DOCUMENT NAME: G:\PDI-2\OysterCreek\MEM93495.wpd h

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MEMORANDUM TO: Docket File FROM: Helen N. Pastis, Senior Project Manager, Section 2 'h Project Directorate l l

Division of Licensing Project Management l Office of Nuclear Reactor Regulation

SUBJECT:

OYSTER CREEK - DRAFT REQUEST FOR ADDITIONAL INFORMATION REGARDING GENERIC LETTER 95-07," PRESSURE LOCKING AND THERMAL BINDING"(TAC NO. M93495)

The attached draft request for additional information (RAl) was transmitted by facsimile I to George Busch of GPU Nuclear to be discussed in a conference call scheduled for June 14, 1999. Review of the RAI would allow the licensee to clarify their understanding of the NRC staff's questions and agree upon a schedule to respond to the RAl. This memorandum and the attachment do not convey a formal request for information or represent an NRC staff position.

Docket No. 50-219

Attachment:

As stated i

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DRAFT

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Oyster Creek

1. The September 5,1996, submittal states that a calculation was used to demonstrate that the isolation condenser return valves, V-14-34 and V-14-35, would operate during pressure loc conditions, that the valves would be modified to increase the margin between actuator capab and the thrust required to overcome pressure locking, and that the valves are cycled during plant cooldown at approximately 500 psig reactor pressure to prevent the valves from pressure locking. A modified industry gate valve thrust equation was used to calculate the thrust require to open these double disk gate vah es during pressure locking conditions. Pressure locking tests sponsored by the NRC were conducted by Idaho National Engineering and Environmental Laboratory on a double disk gate valve. The results of this testing are documented in NUREG/CR-6611, "Results of Pressure Locking and Thermal Binding Tests of Gate Valves."

Test data demonstrated that the modified industry gate valve thrust equation trended with the pressure locking test results but generally underestimated the thrust required to open a pressure-locked valve. '

Discuss the margin between actuator capab"ity and the thrust required to overcome pressure locking for V-14-34 and V-14-35 using GL 89-10 program valve and stem factors and worst case pressure locking conditions.

Explain why it is necessary to cycle these valves during cooldown to prevent pressure locking.

2. 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. 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 )

95-07; system or train, the licensee should perform one of the following within the scope of GL safety 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.

Demonstrate that the actuator has sufficient capacity to overcome these phenomena, or d.

Make 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 surveillance but must retum to the o' pen position, would be evaluated within the scope of GL 95-07.

Your May 9,1996, submittal states that potential accident conditions occurring during testing are not considered pressure locking and thermal binding concems since the probability of an accident during a short time of testing is very low. This does not comply with GL 95-07 scoping guidance. Are there any instances where a valve would be stroked shut for testing and while the valve is shut the upstream and/or downstream pressure could decrease to less than the pressure in the bonnet and the valve may not reopen due to pressure locking defeating the ATTACHMENT

s 1

capability of the safety system or train?- I

3. Your May 9,1996, submittal states that when a valve is subjected to slow pressure and temperature changes, pressure locking and thermal binding will not be a concern since thel

' thermal equilibrium between seat / disc and pressure equilibrium between bonnet occur. Explain the basis for this assumption and describe any valves the were not considered susceptible to pressure locking or thermal binding because of this assumption.

4. Your May 9,1996, submittal states that the isolation condenser steam inlet valves, 31, 32, and 33, are not susceptible to pressure locking because there is steam in the bon the valves. Explain the basis for the assumption that valves with steam in their bonnets wi pressure locking. lock and if this criterion was used on other valves that may be susceptible to press

5. Your May 9,1996, submittal states that a calculation was used te demonstrate that the containment spray recirculation valves, V-21-13 and 17, ere not suscepible to pressu Describe the calculation that was used to demonstrate that the valves are not susceptib pretsure locking.

Explain why these valves are not susceptible to thermalinduced pressure locking durin drywell spray mode of operation. In this mode of operation the valves would be shu be exposed thermalinduced pressure locking conditions due to increased torus temperatu I

6. Identify any valves that are considered not susceptible to pressure locking because the Entergy Hub analysis method demonstrated that the valves would operate during pressure locking conditions. NRC Inspection Report 50-219/94-11 i references this methodology.

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