A93443, Forwards Addl Info as Committed to in Telcon Between Amerenue & NRC Personnel on 990616,re GL 95-07, Pressure Locking & Thermal Binding of MOV Gate Valves

Forwards Addl Info as Committed to in Telcon Between Amerenue & NRC Personnel on 990616,re GL 95-07, Pressure Locking & Thermal Binding of MOV Gate Valves

ML20210H285
Person / Time
Site:	Callaway
Issue date:	07/28/1999
From:	Passwater A UNION ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-95-07, TAC-MA93443, ULNRC-04074, NUDOCS 9908030323
Download: ML20210H285 (6)

Text

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,/' Union Ef2ctric One Ameren Plaza 1901 Chouteau Avenue PO Box 66149 St. Louis, MO 63166-6149 314 621.3 5 2 July 28,1999 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station PI-137 Washington, DC 20555-0001 Gentlemen: ULNRC-04074 g TAC No. MA93443

[II8[E[I DOCKET NUMBER 50-483 UE CALLAWAY PLANT UNION ELECTRIC COMPANY NRC GENERIC LETTER 95-07 PRESSURE LOCKING AND THERMAL BINDING OF MOV GATE VALVES

References:

1) ULNRC-3277 dated October 10,1995

2) ULNRC-3327 dated February 9,1996

3) ULNRC-3333 dated February 15,1996

4) ULNRC-3395 dated June 24,1996

5) ULNRC-4037 dated May 19,1999 References 1-5 provided previous Union Electric /AmerenUE correspondence to NRC concerning Generic Letter 95-07. This letter provides addition information as committed to in a telecon between AmerenUE and NRC personnel on June 16,1999.

If you have additional questions, please contact us.

Sincerely, I

f Alan C. Passwater

/ Manager, Corporate Nuclear Services

[ BEH/DS/jdg x / Attachment  !(;

,)v D $Doh 05b h 83 P PDR a sdsidrary of Amoren Corporation

i STATE OF MISSOURI ) l

) SS CITY OF ST. LOUIS )

Alan C. Passwater, of lawful age, being first duly j sworn upon oath says that he is Manager, Corporate Nuclear Services for Union Electric Company; that he has read the  ;

foregoing document and knows the content thereof; that he has executed the same for and on behalf of said company with  ;

full poFer and authority to do so; and that the facts l therein stated are true and correct to the best of his i knowledge, information and belief.

By h ="

l Alan C. Passwater Manager, Corporate Nuclear Services SUBSCRIBEQ and sworn to before me this EO Ik day l of J#'- , 1999.

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THOMAS J. BOKERN NOTARY PUBLIC-STATE OF MISSOURI ST. LOUIS COUNTY MYCOMMISSION EXPIRES JULY 5,2000

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.A cc: ' M. H.' Fletcher

. . .  : Professional Nuclear Consulting, Inc.

19041 RainesiDrive Derwood, MD 20855-2432 l

Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive Suite 400 -

Arlington, TX 76011-8064 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Jack Donohew (2)

Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 1 White Flint,- North, Mail Stop 13E16 11555 Rockville Pike Rockville, MD 20852-2738 Manager, Electric Department Missouri Public Service Commission P.O. Box 360 Jefferson City, MO 65102 Ron Kucera Department of Natural Resources P.O. Box 176 Jefferson City, MO 65102 Denny Buschbaum TU Electric P.O.' Box 1002 Glen Rose, TX 76043 Pat Nugent Pacific Gas & Electric '

-Regulatory Services P.O. Box 56 Avila Beach, CA 93424 '

1

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• Attachment 1

, Prg's 1 of 3 SUPPLEMENTAL INFORMATION TO:

AMERENUE RESPONSE CONCERNING GENERIC LETTER 95 97 INTRODUCTION in AmerenUE letter ULNRC-4037, dated May 19,1999 AmerenUE provided the Callaway Plant's response to an NRC Request for Additional information concerning Generic Letter 95-07, Pressure Locking and Thermal Binding of MOV Gate Valves.

This letter provides supplemental information to that response following verbal discussions between AmerenUE and the NRC staff.

RAI Question 1 This information is provided to supplement the previous response to question 1 of the RAI, AmerenUE calculation EN-12, Rev. O has been performed to calculate the required thrust to open valves EN-HV-0001/7 for the existing thermally induced pressure locking scenarios. The calculation results, using the Comed / WOG method, show that valves EN-HV-0001/7 hava excess thrust available when opening under the assumed pressure locking scenario.

RAI Questions 1 and 5 in our previous correspondence (ULNRC-4037) a depressurization rate was used for the valve bonnets on EJ-HV-8804A/B and EJ-HV-8811 A/B. This rate was based on '

testing performed by the Westinghouse Owners Group and testing documented in NUREG/CR-6611. In our verbal conversations, the NRC staff indicated that they would not accept depressurization rates based solely on these two sources of data. In order to provide closure for these valves, Ameren UE willimplement the following changes at {

the Callaway Plant. (

l

1) After securing from shutdown cooling, and prior to entering plant Mode 3, valve EJ-HV-8804A/B will be stroked open and then back to its standby closed position. Only the respective valve in the train that was used for shutdown cooling is required to be stroked.

By stroking the valve, any pressure that was trapped in the bonnet would be relieved, and therefore pressure locking is no longer a concern.

2) Due to the effort required to drain and isolate the line, it is not a desirable option  !

to stroke valves EJ-HV-8811A/B. Therefore, a modification to install a locally operated bonnet vent valve will be implemented. For the RHR train used in the shutdown cooling lineup, the vent valve will be opened to relieve any pressure trapped in the valve bonnet after the RHR system is isolated from the RCS and prior to entering plant Mode 3.

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' Attachment 1

, Page 2 of 3 Alternatively AmorenUE and the NRC staff did agree that after a period of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, pressure trapped inside a valve bonnet would be relieved. Therefore, if it is known that '

, there will be at least 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> between the time shutdown cooling is secured and NOP/NOT is reached, the respective EJ-HV-8804 valve (s) is not required to be stroked.

Likewise, the bonnet vent on the respective EJ-HV-8811 valve (s) would not be required to be opened.

IMPLEMENTATION SCHEDULE Yhe modification to the RHR containment recirculation sump valves is scheduled to coincide with the planned opening of the encapsulation tanks. Valve EJ-HV-8811A will be modified during Refuel 11 in the spring of 2001, and EJ-HV-8811B will be modified during Refuel 12 in the fall of 2002.

The operability of these two valves in the interim is justified based on the following reasons. The schedule for the planned refueling outages allows for a time greater than 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> between termination of shutdown cooling and reaching NOP/NOT. However, in the event of an unscheduled shutdown this window may be less than 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

Callaway personnel have performed specific testing which quantified the amount of inleakage to these valves during shutdown cooling operations. During two separate refueling outages following plant shutdown, the volume of water that was inside the bonnets of these valves was measured. During these tests, the maximum amount of fluid found trapped in a valve bonnet was 8.8 gallons. The total volume of the bonnet is 15 gallons.

These RHR recirculation sump isolation valves are only stroke tested after the line has been drained. When the valves are closed, there is no water initially in the bonnet.

Therefore, the measurements performed above demonstrate that significant inleakage to the bonnet does not occur during shutdown cooling operations. Since the valves are always stroked dry, and with no differential pressure, seating of the valve disk is highly

. repeatable.

The above described test data, on the RHR containment recirculation sump isolation valves, demonstrates that inleakage to the valve bonna does not occur to an extent that would pressurize the bonnets. Therefore, the valves remain operable during the period prior to implementation of the above described modification.

RAI Question 2 At the Callaway Plant, the Boron injection Tank (BIT) outlet valves are EM-HV-8801 A &

B. As discussed in the previous NRC correspondence (ULNRC-4037), when calculating the required thrust to open under pressure locked conditions, some pressure is required to be on one side of the valve. Since the RCS side is assumed to be completely depressurized, the CCPs provide the pressure source.

For CCP discharge pressure to be present, valve EM-HV-8803A or B must open. For these two valves, past MOV test data was reviewed. The time for the valves to come I

• Attachment 1 Page 3 of 3 off the seat is 0.81 seconds for EM-HV8803A, and 0.84 seconds for EM-HV-8803B.

- This time frame is consistent with when sufficient discharge pressure is developed from

, the CCPs. Assuming the valve bonnets of valves EMHV8803A/B are pressurized to CCP discharge pressure, EM-HV-8803A will open when the upstream pressure reaches 1200 psig, and EM-HV-8803B will open when upstream pressure reaches 2000 psig.

As discussed in ULNRC-4037, the maximum measured time for the CCPs to reach full speed is 1.5 seconds.

Considering this additional information, the original conclusions for valves EM-HV-8801A & B remain valid. The maximum time these valves will operate at locked rotor conditions (prior to opening) is less than 1.5 seconds.

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