ML20117F104
| ML20117F104 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 04/11/1996 |
| From: | Tabone J GENERAL PUBLIC UTILITIES CORP. |
| To: | |
| Shared Package | |
| ML20117F095 | List: |
| References | |
| GL-95-07, GL-95-7, TR-105, TR-105-R, TR-105-R0, NUDOCS 9605170139 | |
| Download: ML20117F104 (24) | |
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. E Nuc!sar TITLE RESPONSE TO NRC GENERIC LETTER 95-07 PRESSURE LOCKING AND THERMAL BINDING OF SAFETY RELATED POWER OPERATED GATE VALVES Topical Report # 105 I REV. O l
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, Topical Report #105 Rev. 0 Page 2 of'24 I
l ABSTRACT l
l The U.S. Nuclear Regulatory Commission (NRC) has issued generic letter 95-07 to !
request that licensees perform, or confirm that they previously performed, (1) ~
evaluations of operational configurations of safety-related, power-operated (including motor , air , and hydraulically operated) gate valves for susceptibility to pressure locking and thermal binding and (2) further analyses, l and any needed corrective actions, to ensure that safety-related power-opertAsd '
gate valves that are susceptible to pressure locking or thermal binding e'.a !
capable of performing their safety functions within the current licensing bases of the facility.
I In the generic letter, tLa NRC staff is requesting a detailed evaluation and i resolution of the issue of pressure locking and thermal binding (PLTB) of the ;
safety related power operated gate valves. This report provides a response to j the actions required by the generic letter.
i GPUN has reviewed all safety-related power-operated gate valves totalling 57. l A logic was developed to evaluate susceptible gate valves whose safety function )
could be affected by PLTB concern. There are 20 valves wich need to open from j a closed position either during testing or from a Lormal position to satisfy the open safety function. All valves were found not to be potentially affected by 4 PLTB to satisfy their safety function for the current licensing basis of OCNGS.
The Isolation condenser (ICS) Condensate Return valves V-14-34, 35 are pc u tially susceptible to the system induced pressure locking phenomenon but eva? ation,s heve shown that:
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- 1) The valves are not taken credit for in the plant specific Appendix l K accident analysis 1
- 2) Reactor pressure during events where the MOVs may be used will not l result in the valves being prestume locAed, and
- 3) Emergency operating procedu ms direct the operators to alternate means of reducing reactor prersure, should the IC be unavailable, ,
for whatever reason. !
The Core Spray Maintenance valves are also potentially susceptible to pressure locking, should a LOCA occur while the valves are closed and a parallel injection valve is open. This occurs while stroke time testing the parallel injection i valves at power. The Core Spray system is currenMy cor'sidered inoperable during I this test and therefore the system is not taken < recit for during periods where the valves ara closed and this phenomenon car potentially take place. GPUN is evaluating the subject valves during such an event to determine whether the valves can be qualified and are capable to open under all credible scenarios such that the administrative controls would no longer need to be relied upon.
The Core Spray Parallel Injection valves were modified CJrjn:j the last refueling outage (15R) to alleviate the potential for pressure locking in these valves (drilled discs).
Calculations show that the containment Spray Recirculation valves W1. not become i pressure locked. These valves could experience pressure (=90 psi) .- the valve {
bonnet and zero pressure on either side of the valve following an event requiring ;
':ywell spray; however, this will not result in the valves being pressure locked. l i
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TABLE OF CONTENTS !
l Article ERES 1.0 7"TRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.0 DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.0 ASSUMPTIONS, METEODS AND EVALUATION CRITERIA . . . . . . . . . . . 5 3.1 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . 5 3.2 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.3 Evaluation Criteria . . . . . . . . . . . . . . . . . . . . 7 4.0 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.1 Category 1 valves (Table 1) . . . . . . . . . . . . . . . 8 4.2 Category 2 Valves (Table 2) . . . . . . . . . . . . . . . . 8 4.3 Category 3 Valves (Table 3) . . . . . . . . . . . . . . . . 8 l 4.4 Category 4 Valves (Table 4) . . . . . . . . . . . . . . . . 12
5.0 CONCLUSION
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6.0 REFERENCES
. . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 ATTACEMENT 1 GL 95-07, PLTB Evaluation Methodology
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, ATTACEMENT 2 Listing of all Power Operated Safety Related Gate Valves l for OCNGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
- TABLE 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 TABLE 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 TABLE 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 i TAELE 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2
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, Topical Report #105 Rev. O Page 4 of 24
1.0 INTRODUCTION
The U.S. Nuclear Regulatory Commission (NRC) has issued generic letter 95-07 to request that licensees perform, or confirm that they previously performed, (1) evaluations of operational configurations of safety- l related, power-operated (including motor , air , and hydraulically l operated) gate valves for susceptibility to pressure locking and thermal binding and (2) further analyses, and any needed corrective 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 within the current licensing bases of the facility.
NRC previously provided guidance on an acceptable approach for addressing pressure locking and thermal binding of motor-operated valves (MOVs) in Supplement 6 to Generic Letter (GL) 89-10, " Safety-Related Motor-Operated Valve Testing and Surveillance," but did not request specific actions by licensees to address these problems at that time. GL 95-07 confirms (as was indicated earlier in Supplement 6) that licensees are expected, under existing regulations, to take actions as necessary to ensure that safety-rs.ated power-operated gate valves susceptible to pressure locking or thermal binding are capable of performing their required safety functions.
For MOVs and other power-operated valves, GL 95-07 requires that licensees submit for staff review summary information regarding any actions taken '
to ensure that valves susceptible to pressure locking (PL) or thermal binding (TB) are capable of performing their required safety functions.
In this generic letter, the NRC staff is requesting a detailed evaluation and resolution of the issue of pressure locking and thermal binding (PLTB) of the safety related power operated gate valves. This report provides a response to the actions required by the generic letter.
2.0 DEFINITIONS 2.1 Differential Pressure Lockinu - One condition that can result in bonnet pressurization occurs when the gate valve (flex wedge and double disc design) is closed and a differential pressure exists ;
across the valve disc. The pressurized side of the flexible disc i may move slightly away from its coat thereby allowing high pressure 1 water to enter the bonnet cavity. With time, the bonnet cavity l pressure will tend to equalize with the pressurized side of the valve body. If the system pressure decreases rapidly, the bonnet cavity pressure may become trapped and force both disc seating surfaces against the valve body seating surfaces. The differential pressure can cause the val-re disc / seat frict W forces to become excessively high and thus prevent the gate ulve from reopening.
2.2 Liould Entracment fThermal Induced Pressure Lockino-TIPL) -
A second condition that can result in bonnet pressurization occurs when the system, including the valve bonnet cavity, is full of cold ;
water with the gate valve closed. As the system temperature or !
ambient temperature increase, heat is conducted through the valve body / bonnet / disc surfaces of the closed gate valve. As a result, the cold water inventory becomes heated and causes the bonnet cavity temperature to increase which results in potentially high j pressure. High bonnet cavity pressure, resulting from liquid i entrapment and thermal expansion of the confir.ad water inventory, can cause the valve disc / seat friction forces to become excessively hfgh and then thus prevent the gate valve from reopening.
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i Page 5 of 24 2.3 Valve Disc / Seat Thermal Bindino - This condition can occur during system shutdown and results when the gate valve (all designs except
- parallel disc type) ' body / seat contracts a greater amount during cooldown than the valve disc.- The differential in thermal contraction causes the valve disc to become " pinched" in the valve seat. Gate valves that are closed while the system is ]E2I and are
- allowed to cocidown may experience excessive disc / seat thermal binding that prevents valve reopening until the valve has been reheated. Valve stem and yoke failures have occurred during j attempts to reopen thermally bound gate valves.
- 2.4 Excessive Closure Force - This force can result in gate valve disc / seat binding and can contribute to the adverse affects of
- thermal binding. The excessive closure force causes the valve disc to be driven tighter into the valve seats. Potential causes of excessive closure forces are 1) manual closure, 2) excessive 1
service air pressure to the valve air operator, 3) misadjusted or i defective torque switches on the valve motor operator, 4) inertial e
movement of the motor / gear train after the mot >r operator has been i
de-energized, and 5) stem grovth af ter closure (cold portion of the stem heats up due to hot process fluid and forces the disc further
- j. into the seat).
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! 3.0 ASSUMPTION 5, METEODS AND EVALUATION CRITERIA i
! 3.1 Assumptions 3.1.1 Power operated safety related valves functionally required to achieve and maintain hot shutdown are in the scope of this evaluation, since hot shutdown is the licensing basis safe shutdown for OCNGS (Ref. 6.4).
3.1.2 Inadvertent position change will not be considered. This is consistent with the GL 89-10 Supplement 4 for BWRs.
3.1.3 If the system is declared inoperable during valve testing 1.e. inservice testing (IST), Engineered Safeguard (ES) testing or post maintenance test (PMT), PLTB concern does not apply for the test duration. Since the system is inoperable, valve function is not required. However, PLTB still has to be evaluated to ensure that valve damage has not occurred during testing which could cause the valve to be unable to perform its safety function during normal operation.
3.1.4 For the systems which are considered operational during testing-(IST, ES, PMT), PLTB concern shall be evaluated for testing. Potential accident conditions occurring during the test is not considered for PLTB concern since the probability of an accident during a short time of testing is very low.
3.1.5 When the valve is subjected to slow pressure and temperature changes, PLTB will not be a concern since the thermal equilibrium between sest/ disc and pressure equilibrium between bonnet and the piping will occur.
3.1.6 PLTB will not be a concern due to normal ambient temperature changes at the valve location. These changes are slow and therefore .will not cause high temperature differentials that can create PL or TB.
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3.1.7 No credit is taken for check valve's capability to isolate a high pressure source to eliminate consideration of the potential for PLTB.
3.2 Methods The PLTB evaluation methodology was developed based on the guidelines in the GL 95-07 and other industry sources. The following matrix and Attachment 1 to this report provides the criteria sised for selecting the valves for evaluation of PLTB.
.- mmanmaarm valve NormC Pceition Safety Test or Evaluate gPonation Surveillance Susceptibility Position Within Scope of i
anuaasasa w =a n w:mm.=
GL 95-07 4
Normally closed Opn Closed Yes Normally Cl_osed Open Open Yes Normally Open Open Closed Yea I Normally Closed Closed Closed No Normally closed Closed Open No Norma 13y Open Open Open No Normally Open Closed Closed No Normally Open Closed Open No Attachment 2 is a list of all power-operated safety-related gate valves at OCNGS. Using the above matrix, the valves have been j placed into four categories as follows:
3.2.1 Cateoorv 1 These valves that do not have an open safety function from a closed position and either no surveillance test is performed or valve is not fully closed for surveillance at power operation or hot shutdown. These valves do not have PLTB concern as per above matrix. These valves are listed in attached Table 1.
3.2.2 C_aiscorv a 2 These valves do not have an open safety function from a closed position and have a close safety function. These valves are fully stroked during testing. If the valve cannot be opened frotn closed position, the valve will satisfy its safety function. These valves do not have PLTB concern per above matrix. These valves are listed in Table 2.
3.2.3 Cateoorv 3 These valves are normally open and have an open safety function. These valves havn an open function from a closed position due to testing requirements. These valves will be evaluated for PLTB concern. These valves are listed in attached Table 3.
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, Topical Report #105 Rev. O Page 7 of 24 3.2.4 Cateoorv 4 These valves have an open safety function from a normally closed position. These valves are listed in attached Table 4 and will be , valuated for PLTB concern.
J 3.3 Evaluation Criteria 1
For pressure locking and thermal binding evaluation, following evaluation criteria will be used for each susceptible valve.
Pressure Lockino
- 1. Pressure source can be from the valve seat leakages upstream and/or downstream of the valve under consideration.
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- 2. Pressurization can occur from a pump start in the system.
- 3. Bonnet pressurizatioa can occur due to local ambient temperature increase due to normal operation or accident condition. Peak ambient normal operating and ambient accident temperatures are based on ES-027 (Ref. 6.7). The rate of pressure rise for low syntem temperature (approximately 100*F) l is 33 psi per l'F temperature rise in a solid filled bonnet. ,
The rate of pressure risa can be as high as 100 psi per l'F I temperature increase for system temperature above 450*F l (Ref. 6.2). '
- 4. Pressurization of the bonnet can occur due to initial cold fluid and then hot fluid flow due to position change.
- 5. There is no pressure threshold below which PL could not occur. j
- 6. Consider operational changes resulting in pressurization of the valve bonnet. !
- 7. Solid wedge disc valves are not affected by PL concern.
However, bonnet pressurization due to thermal affects will be evalcated for these valves.
- 8. PL is not a concern when the valve opens against a line pressure equal to or greater than a pressure in the bonnet since the valve is designed to operate for the disc pressure differentin1.
Thermal Bir. ding
- 1. Thermal binding is not a concern for system temperatures below 221*F for flex wedg.a valves and below 166*F for solid wedge gate valves. Above these temperatures, the AT for TB concerns are 100'1' for flex wedges and 50*F for solid wedge gate valves. (Eof. 6.10) i
- 2. Consider differences in valve disc and seat materials and !
wall thicknesses resulting in differential expansion. l 1
- 3. Consider valve stem growth due to thermal expansion resulting in high closing force.
- 4. Consider the scenario when the valve is close' at hot ,
condition and is required to open at lower temperature. I l
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Page 8 of 24 4.0 RESULTS The valves in each category described in section 3 are evaluated in detail l here:
4.1 Category 1 Valves (Table 1) i
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None of these valves have an open safety function from a closed position. Surveillance test is either not performed or is performed in cold shutdown or while system is considered inoperable per Ref 6.13. Therefore, these valves will not be evaluated further.
4.2 Category 2 Valves (Table 2)
These valves have a closed safety function. None of these valves have an open safety function from a closed position. During the test, if the valve does not open from the closed position, it will satisfy the safety function. For normally open valves, the safety function is to close which cannot be affected by PLTB. Thus, for these valves PLTB is not a concern and no further evaluation will be performed.
4.3 Category 3 Valves (Table 3)
These valves are normally open and have an open cafety function.
These valves have an open function from a closed position due to testing requirements. The surveillance test is performed periodically. This will assure periodic operability of the valve.
Each of the valves in the category is evaluated as follows:
V-14-30. 31, 32, 33: Isolation Condenser Steam Inlet valve size: 10" l Valve Disc Design: Parallel Disc Ref. Dwg: W9023253 Valve Location: Reactor Bldg. el. 75' l
Function:
Normal Operation - No function, valves are normally open l Accident Condition -
Open: Valves remain open to provide a flowpath between the Reactor and the Isolation condensers to remove fission product decay heat after reactor isolation scram when the main turbine condenser is not available as a heat sink. These valves are normally open and no change in position is required to achieve this safety function.
Close: To isolate a High Energy Line Break (HELB) in the system piping. The valves are not required to reopen following an isolation.
PL: The system is considered inoperable while the valves are closed for IST therefore an accident need not be postulated while valves are being tested. Under normal test conditions, reactor pressure will be present both upstream and downstream of the valves. Therefore, pressure locking is not a concern.
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Topical Report #105 Rev. O Page 9 of 24 )
l During normal operation and testing conditions, these ;
valves are exposed to reactor steam. Since the valves are j
- only closed momentarily during testing, there is 4
insufficient time to condense the fluid in the bonnet.
Furthermore, even if the reactor steam at =550*F in the )
bonnet did condense, there is no-heat source which could I heat the fluid beyond its original condition. Therefore
- they are not impacted by liquid entrapment, i TB Not a concern based on parallel disc design. ;
V-14-36. 37: Isolation Condenser Condensate Return Isolation I Valve size: 10" Valve Disc Design: Flex Wedge Ref. Dwg: 2085-5 Valve Location: Drywell el. 49-9' Functions i
Normal Operation - No function, valves are normally open Accident Condition -
open: Valves remain open to provide flowpath between Reactor and the Isolation Condensers to remove l fission product decay heat after reactor isolation j scram when the main turbine condenser is not available as a heat sink. These valves are normally open and no change in position is required
- to achieve this safety function.
Closed: To isolate a HELB in the system piping. The valves are not required to reopen following an isolation.
PL: The system is considered inoperable while the valves are closed. Under normal test conditions, reactor pressure I will be present both upstream and downstream of the valves.
Therefore, pressure locking is not a concern.
During normal operation and testing conditions, these valves are exposed to reactor recirculation system coolant at =525'F. Since there is no heat source relative to the valve bonnet fluid, they are not impacted by liquid entrapment.
TB: During testing, the valves are exposed to reactor recirculation coolant. Accident condition concurrent with testing is not considered since the system is declared inoperable during the testing. Valve opens from closed position during test at essentially the same temperature.
Therefore, TB is not a concern.
V-20-12: Core Spray System I Pump Discharge Valve Valve Sizes 8" Valve Disc Design: Flex Wedge Ref. Dwg: 2077-5 Valve Location: Reactor Bldg. el. 51' NW Quadrant 013/028R0 9
, t Topical Report #105
, Rev. O Page 10 of 24 Function:
Normal Operation - No function. Valve is normally open. Valve is closed during surveillance testing at power while the Parallel Injection valves are stroke tested to ensure elevated reactor pressure does not enter the low design pressure portion of the Core Spray system. When reactor pressure is below 350 psi, this valve is also closed while the Core Spray pumps are tisted to ensure core spray system flow does not enter the reactor.
Accident Condition -
Open: Valve remains open to provide flow path for Core Spray system to Parallel Injection valves.
Closed: Valve is not closed during an accident.
PL: The system is presently considered inoperable while the valves are closed. If either Core Spray testable check valve (V-20-150 or 152) leaks then when the Parallel Injection valve is opened, reactor pressure will be
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d downstream and in the bonnet. The valve is not required to realign if an accident were to occur while . testing since the system is considered inoperable (Reference 6.14) . This will not result in pressure locking but as a " Differential
! Pressure" opening against reactor pressure. This will not l degrade the valve since it is designed for 1250 psid (Reference 6.3). Therefore, pressure locking is not a present concern.
Bonnet pressurization due to thermal effects cannot occur j- since the valve is closed for such a short duration (only 4
as long as is required to stroke test the Parallel Injection valves).
t i TB: The valve is normally open and exposed to torus water at
-105"F. When the valve is closed for testing, it may be exposed to reactor coolant leakage past the testable check valves and Parallel Injection valves (opened during testing). There is insufficient time for possible temperature changes to effect this valve since it is closed for such a short duration. In addition, if reactor coolant does reach this valve while closed, the valve will heat up as opposed to cool down, prior to reopening. Therefore, TB is not a concern.
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. Rev. O Page 11 of 24 V-20-18: Core Spray System II Pump Discharge Valve i Valve Sizes 8" Valve Disc Design: Flex Wedge Ref. Dwg: 2077-5 Valve Location: Reactor Bldg. el. 75' SW Quadrant Functions I Normal Operation - No function. Valve is normally open. Valve !
! is closed during surveillance testing at power while the
, Parailwl Injection valves are stroke tested to ensure elevated 4
reactor pressure does not enter the low design pressure portion j of the Core Spray system. When reactor pressure is below 350
! psi, this valve is also closed while the Core Spray pumps are 4
tested to ensure core spray system flow does not enter the reactor.
Accident Condition -
! Open: Valve remains open to provide flow path for Core Spray system to Parallel Injection valves.
closed: Valve is not closed during an accident.
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- The system is presently considered inoperable while the j valves are closed. If either Core Spray testable check i valve (V-20-151 or 153) leaks then when the Parallel
, Injection valve is opened, reactor pressure will be
! downstream and in the bonnet. The valve is not required to
, realign if an accident were to occur while testing since
! the system is considered inoperable (Reference 6.14) . This a
will not result in pressure locking but as a " Differential Pressure" opening against reactor pressure. This will not i '
degrade the valve since it is designed for 1250 paid (Reference 6.3). Therefore, pressure locking is not a present concern.
Bonnet pressurization due to thermal effects cannot occur since the valve is closed for a short duration (only as long as is required to stroke test the Parallel Injection valves).
TB: The valve is normally open and exposed to torus water at
=105'F. When the valve is closed for testing, it may be exposed to reactor coolant leakage past the testable check valves and Parallel Injection valves (opened during testing). There is insufficient time for possible temperature changes to effect this valve since it is closed for such a short duration. In addition, if reactor coolant does reach this valve while closed, the valve will heat up as opposed to cool down, prior to reopening. Therefore, TB is not a concern.
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] V-21-13. 17: Containment spray Recirculation valve 1 j
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- Valve sizes 6"
- Valve Disc Design Flexible wedge Ref. Dwg
- 6-2206 Valve Location: Reactor Bldg.'el. 23' f Functions Normal Operation - Valve is normally open, which would provide
- a recirculation flow path for the containment spray system back i' to the Torus. The containment Spray system is normally in standby with the piping void of liquid. The system is operated i manually, such that the valves are aligned (either to spray the j' drywell or cool the terus water) before the pumps are started.
- The valves remain open while the pumps are being tested.
l Accident Condition -
) Open: To provide a recirculation flew path for the
- Containment Spray system.to the Torus to cool the i
torus water via the Containment Spray Heat Exchangers (" Torus cooling" mode).
- close
- To allow flow to the drywell and wetwell spray headers when the containment Spray system operates j in the "Drywell Spray" mode.
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PL During normal operating and test conditions this valve is not impacted by differential pressure locking since the
, valves remain open whenever system pressure is present.
, During an accident, the valves will be aligned prior to
! operating the pump. When the system operates in "Drywell Spray" mode, system pressure at the valve will be less than i
100 psi. Thus it is doubtful that the valve will " flex" s and allow system pressure to reach the bonnet. However, in '
the unlikely event the valve bonnet becomes pressurized to 90 psi, the resulting calculated " pressure locking" forces are minimal compared to the MOV capability (Reference 6.5).
Therefore, system induced pressure locking is not a concern.
Bonnet pressurization (TIPL) cannot occur due to test ;
configurations since the valve is not closed while the '
systeem is pressurized. The valves are normally open and remain open for accidents which occur outside the drywell.
Therefore, ambient temperature changes due to accidents outside the drywell will not effect these valves' functional requirements.
TB: These valves are exposed to torus water which remains below 160*F, during normal and accident conditions (Reference 6.8). Thus, TB is not a concern.
4.4 Category 4 Valves (Table 4)
These valves have an open safety function from a normally closed position. Therefore, pressure locking and thermal binding concern will be evaluated for each valve as follows:
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Topical Report #105 Rev. O Page 13 of 24 V-14-34, 35: Isolation Condenser Condensate Return valve size: 10" Valve Disc Design Parallel Disc Ref. Dwg: W9023271 Valve Location: Reactor Bldg. el. 75' (overhead)
Function:
Normal Operation - Isolate the Isolation Condenser flow from the l Reacter Vessel. Valves are normally closed.
Accident Condition -
] Open: Valves - open on ES signal (Low-Low level, High l 4 Reactor pressure) to provide flowpath between '
Reactor and the Isolation Condensers to remove fission product decay heat after reactor isolation scram when the main turbine condenser is not available as a heat sink. 1 Close: To isolate a HELB in the system piping. The valves are not required to reopen following an isolation.
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l PL These valves are potentially susceptible to system induced l pressure locking during a large break LOCA. Reactor l coolant pressure (1020 psi) enters the valve (bonnet) when )
the valve is periodically stroked. However, OCNGS has 1 4
revised the plant specific Appendix K analysis to assume !
only Core Spray and Au omatic Depressurization Systems 4
available and the Isolation Condenser system inoperable.
Therefore, if V-14-34 and V-14-35 become pressure locked,
- it is not a nuclear safety concern.
' The Emergency Operating Procedures (EOPs) which utilize the isolation condensers to reduce reactor pressure and remove energy 1
- also provide direction to utilize other means of 1 1 accomplishing these functions if the isolation condensers are not available. Additionally, HELB analyses have shown i that the reactor is isolated at 400 psi, which is greater than the calculated reactor pressure at which these valves are susceptible to pressure locking, assuming 1020 psi remains in the valve bonnet (Reference 6.6). Accordingly, pressure locking is not a concern for any of these scenarios and the ICS would be available for operator action.
GPUN evaluated these valves for modification to alleviate any potential concern for pressure locking (Peference 6.12) even though the modification is not required for the valves to perform their safety function, as described above. To mitigate potential pressure locking of these valves, the valve bonnets would need to be vented. However, such a modification would result in either degrading the containment or HELB isolation capability or the normal system recirculation isolation capability of these valves.
As discussed above, the EOPs describe alternate means of reducing reactor pressure and removing energy in the event the ICs are not available. Therefore, the modification is not being pursued.
The valves are stroked monthly, thereby supplying fresh
" hot" reactor coolant to the valve and bonnet (valves are located at a high point from the tie-in points to Reactor Recirculation system). As the valve remains closed during 013/028R0
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- Page 14 of 24 normal' operation, the fluid in the bonnet may cool, not j heat up further, unless there is a leak in the valve. If a there is a leak in the valve, the leak itself will prevent j the fluid from pressurizing the bonnet. Also, the worst i
case accident environment (267'F), ~resulting from the f redundant IC HELB,.will not. produce a heat source to the j valve bonnet sufficient to heat the fluid beyond which it was to start with. Therefore, TIPL is not a concern.
TB: Not a concern based on parallel disc design.
V-20-15, 21, 40. 41: Core Spray System Parallel Injection Valves valve Size 8" i Valve Disc Designs. Flex Wedge Ref. Dwg: 2079-5
! Valve Location: Reactor Bldg. el. 75' SW Quadrant 3
Reactor Bldg. el. 51' NW Quadrant
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Functions
! Normal Operation - No primary function. A secondary function l is to provide high pressure - low pressure isolation for leakage j past the testable check valves. Valves are periodically cycled j for surveillance stroke time tests. Core Spray system is a !
j . standby ECCS system. Valves are normally closed.
{ Accident Condition -
]
Open: Valves open in response to an~ECCS signal and reactor pressure less than 285 psi to provide flow path for core Spray system to reactor vessel. l Closed: Valves may be periodically closed (operator action) in order to maintain reactor water level within 1 band during Small Break LOCAs.
l PL: The valves were modified in 15R outage (drilled disc) to alleviate this potential concern.
TB System fluid is torus water at temperatures below 160*F during normal and accident conditions (Reference 6.8), 1 which is below the threshold for thermal binding. . Valves may be exposed to reactor water via leakage past the system i check valves. However, should this occur, the fluid temperature at the valve would remain constant. Thus the valves are not susceptible to TB.
v-21-5, 11: Containment Spray Drywell Spray Valves valve size: 14" Valve Disc Design: Solid wedge Ref. Dwg 2713-Z4 (1537-X)
Valve Location: Reactor Bldg. el. 23', 51' Function:
Normal Operation - Valve is normally closed, preventing water i from spraying the drywell. The Containment Spray system is normally in standby with the piping void of liquid. The system is operated manually, such that the valves are aligned (either to spray the drywell or cool the torus water) before the pumps are started.
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, Topical Report #105 Rev. O Page 15 of 24 Accident Condition -
Open: To provide a flow path for the containment spray system to spray the drywell to cool and depressurize the drywell following a LOCA inside the drywell.
Close Isolate drywell spray and allow the containment spray system to operate in the " Torus cooling" mode.
PL Not a concern based on solid wedge dise design.
TB: These valves are exposed to torus water which remains below 160*F, during normal and accident conditions (Reference 6.8). Note too, that the Torus water heats up during the accident as opposed to cooling down. Thus, TB is not a Concern.
V-21-15, 18: Containment Spray Torus Spray Valves Valve Size 4" Valve Disc Design Flexible wedge
- Ref. Dwg: P-31193-7 Valve Locations Reactor Bldg. el. 23'
- Valve is evaluated as flexible wedge, which is conservative. Valve disc ,
details are not available. '
Function:
Normal Operation - Valve is normally closed, providing additional isolation between the torus air space and the drywoll. The containment Spray system is normally in standby with the piping void of liquid.
Accident Co,ndition -
Open: To provide a flow path for the containment spray system to spray the torus while the system is spraying the drywell to maintain the torus cool following a LOCA inside the drywell. The valve opens when the system flowrate exceeds 1500 gpm for 20 seconds in the "Drywell spray" mode.
Closes Isolate torus spray and allow the containment spray system to operate in the torus cooling mode when flow no longer exceeds 1500 gpm to the Drywell.
PL Valve opens while the system is in service, spraying the torus. This opening is a " differential pressure" opening since the system is in service. When the valve is closed, system pressure will not deviate to any degree from when the valve is required to open. Therefore, pressure locking is not a concern.
The valve receives a signal to open after flow is i established while the system operates in the "Drywell l Spray" mode. "Drywell Spray" is used for accidents which l
occur in the drywell. Since the valve is located outside the drywell, the ambient temperature at the valve will not be adversely ef fected during an accident in which the valve must open. Therefore, TIPL is not a concern.
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1 l , Topical Report #105 j Rev. 0
, Page 16 of 24 TB These valves are exposed to torus water which remains below j 160*F, during normal and accident conditions (Reference 4
6.8). Note too, that the Torus water heats up during the j accident as opposed to cooling down. Thus, TB is not a
- concern.
l
5.0 CONCLUSION
S 1
. All safety-related power-operated - gate valves were evaluated in this
- report for their susceptibility to pressure locking and thermal binding phenomena. They were further evaluated for their capability to perform
- their required safety function. For some of these valves the possibility
- of PLTB does exist, but their safety function is not affected since the j valve position changes to safety position before PLTB can affect the valve
- function. All valves were found not to be affected by PLTB concerns, except Core Spray Maintenance valves V-20-12,18 (during test, only) . The l Core Spray system is presently considered inoperable while valves V-20-12, i 18 are closed (Reference 6.14). Evaluations are ongoing to determine i whether the valves should be qualified to operate under such scenarios.
i
6.0 REFERENCES
i 6.1 NRC GL 95-07, " Pressure Locking and Thermal Binding of Safety Related Power Operated Gate Valves," dated Aug. 17, 1995.
! 6.2 NRC Nureg 1275, Volume 9, " Operating Experience Feedback Report -
! Pressure Locking and Thermal Binding of Gate Valves."
$ 6.3 Anchor Valve Drawing 2077-9, "8 Inch 600# Gate valve, Pressure Seal DM" l 6.4 OCNGS Updated Final Safety Analysis Report (FSAR). !
l 6.5 GPUN Calculation, C-1302-241-5310-072, " Pressure Locking Evaluation j - Containment Spray" s
! 6.6 GPUN Calculation, C-1302-211-5310-087, "V-14-34 and 35 Reactor j Pressure for Pressure Locking" 6.7 GPUN Engineering Standard, ES-027, "OCNGS Environmental i Parameters." i 6.8 GPUN Technical Data Report 993, " Evaluation of Containment Spray j
s
/ ESW Performance at Elevated Intake Temperature" j 6.9 GPUN Technical Data Report 1128, " Evaluation of Pressure Locking i and Thermal Binding of GL 89-10 Gate Valves at Oyster Creek" J
j 6.10 GPUN Memo 5310-95-282, "B&WOG Working Group Meeting," dated j December 7 and 8, 1995.
1 j 6.11 NRC GL 89-10, supplement 4, " Consideration of Valve Hispositioning j <
in Boiling Water Reactor,",, dated February 12, 1992.
i 6.12 GPUN Memo 5310-95-019, dated 1/30/95, "TFAAI AT7442" 6.13 Oyster Creek Nuclear Generating Station Pump and Valve Inservice Testing Program, Rev. 8.
6.14 GPUN Memo 2100-96-052, dated 2/13/96, " Interim Guidance for Core Spray System surveillances."
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- Topical Report #105 Rev. O Page 17 of 24 ATTACIDGDIT 1 GL 95-07, PLTB Evaluation Methodology 1
ALL SAFETY RELATED WALVES 4
1 P
ARE TNEY NO GATE ;- NOT A PLtB VALVE 5? ; DETEllbf!NE CONCERN 4
DjlC DESIGN i I
YES 4'
1r it 2
DI5C SOLID YES A RE WEDGE? ; NOT A PL VALVE 5 af0 power NOT IN TNE CONCERN
- SCOPE OF OPE R ATE 0? / GL 95-97 N0 i vel I'
q' EVALUATE FOR PL CONCERN 15 fMERE a safe f e FUNCf!ON TO C#E N F AOM A eso NosanaLLv CLOSED DA a Not A Ptig CLOSED PO5!?IDN CONCERN 1 RELATED 10 TE5flNG'
\
IS O!SC YES TES PanALLEL SEAT ;
ogslGNS s.07 A Te CONCERN a
P j
i IS THE Flos THAu YE5
' THE WaLV[ ;
P(T5 J5 NOT &
Ga5 04 CONCEAN l' AIRS --
-i EVALUATE FDA 1 78 CONCERN uO P
PL
- Presswee Lock eng TS
- Theemal Sinding
I.
i l' t, .
l .
- Topical Report #105
' Rev. O Page 18 of 24 ATTACBIMIT 2 Listing of all Power Operated
, Safety Related Gate Valves for OCNGS
{
l l
l l
t-l 1
l Ol3/028R0
Topical Report h105 G P U N U C L E A R
- O Y S T E R C R E E K Page 19 of 24 .
NSR GATE VALVES W/ POWER
==================================================================================------ ==============---- --=========
TAG NUMBER COMPCODE TYPE SIZE VALVOP MANUFACTURER NAMF MODE NUMBER -
==============================================================------------- ============================L ===============
V-14-0030 VALVE GATE 10.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) TYPE DD V-14-0031 VALVE GATE 10.0 M0 ANCHOR / DARLING VALVE COMPANY (A0008) TYPE DD V-14-0032 VALVE GATE 10.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) TYPE DD V-14-0033 VALVE GATE 10.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) TYPE DD V-14-0034 VALVE GATE 10.0 M0 ANCHOR / DARLING VALVE COMPANY (A0008) TYPE DD V-14-0035 VALVE GATE 10.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) TYPE DD V-14-0036 VALVE GATE 10.0 M0 ANCHOR / DARLING VALVE COMPANY (A0008) 2085-5 V-14-0037 VALVE GATE 10.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) 2085-5 V-16-0001 VALVE GATE 6.0 M0 V-16-0002 VALVE CATE 6.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) 2091-5 HIRATA VALVES 4-FWA-V-36A V-16-0014 VALVE GATE 6.0 MO V-16-0061 VALVE GATE 6.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) 2091-5 ANCHOR / DARLING VALVE COMPANY (A0008) 2091-5 V-17-0001 VALVE GATE 10.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) FLEXWEDGE v-17-0002 VALVE GATE 10.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) FLEXWEDGE V-17-0003 VALVE GATE 10.0 MO VELAN VALVE CORPORAT10N(02685) B16-2054B-02TS V-17-0019 VALVE GATE 14.0 MO VELAN VALVE CORPORAT10N(02685) B19-7054P-13MS V-17-0054 VALVE GATE 14.0 MO VELAN VALVE CORPORAT10N(02685) B19-7054P-13MS V-20-0003 VALVE GATE 12.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) 2065-5 V-20-0004 VALVE GATE 12.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) 2065-5 V-20-w;*2 VALVE GATE 8.0 MO V-r 0015 VALVE Gaiu MO ANCHOR / DARLING VALVE COMPANY (A0008) 600-5-WE 8.0 ANCHOR / DARLING VALVE COMPANY (A0008) 600-5-WE V-20-0018 VALVE CATE 8.0 M0 V-20-0G21 VALVE GATE MO ANCHOR / DARLING VALVE COMPANY (A0008) 600-5-WE 8.0 ANCHOR / DARLING VALVE COMPANY (A0008) 600-5-WE V-20-0032 VALVE GATE 12.0 M0 ANCHOR / DARLING VALVE COMPANY (A0008) 2065-5 V-20-0033 VALVE GATE 12.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) 2065-5 V-20-OO40 VALVE GATE 8.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) 600-5-WE V-20-0041 VALVE CATE 8.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) 600-5-WE V-21-0001 VALVE GATE 12.0 MO OHlO INJECTOR COMPANY (A0087) FIG.1503N-70-993 V-21-0003 VALVE GATE 12.0 MO OHIO INJECTOR COMPANY (A0087) FIG.1503N-70-998 V-21-0005 VALVE GATE 14.0 MO OHIO INJECTOR COMPANY (A0087) FIG.1503N-70-998 U-21-0007 VALVE GATE 12.0 MO OHIO INJECTOR COMPANY (A0087) FIG.1503N-70-998 V-21-0009 VALVE GATE 12.0 MO OHIO INJECTOR COMPANY (A0087) FIG.1503N-70-998 V-21-0011 VALVE GATE 14.0 MO OHIO INJECTOR COMPANY (A0087) FIG.1503N-70-998 V-21-0013 VALVE GATE G.0 MO PACIFIG VALVES / MARK CONTROLS CORPORAT10N(10502) 150-3-WE V-21-0015 VALVE GATE 4.0 MO VELAN VALVE CORPORAT10N(02685) 0648 V-21-0017 VALVE GATE 6.0 MO PACIFIC VALVES / MARK CONTROLS CORPORATl0N(10502) 150-3-WE V-21-0018 VALVE GATE 4.0 MO VELAN VALVE CORPORATl0N(02685) 0648 V-21-0075 VALVE GATE 4.0 M0 ANCHOR / DARLING VALVE COMPANY (A0008) W8321853 V-21-0076 VALVE GATE 4.0 MO ANCHOR / DARLING VALVE COMPANY (A0008) W8321853 V-37-0009 VALVE GATE 26.0 M0 CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592) 608 WEOS V-37-0010 VALVE GATE 26.0 MO V-37-0011 CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592) 608 WEOS VALVE GATE 2.0 MO V-37-0020 CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592) 608 WEOS VALVE GATE 26.0 MO V-37-0021 CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592) 608 WEOS VALVE GATE 26.0 MO 608 WEOS V-37-0022 CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592)
VALVE GATE 2.0 M0 608 WEOS V-37-0031 CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592)
VALVE GATE 26.0 MO 608 WEOS V-37-0032 CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592)
VALVE GATE 26.0 MO 608 WEOS
" 37-0033 CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592)
VALVE GATE 2.0 MO 608 WEOS
'-0042 CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592)
VALVE GATE 26.0 MO 608 WEOS
'043 VALVE CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592)
GATE 26.0 MO 608 WEOS 4 VALVE CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592)
GATE 2.0 MO 608 WEOS VALVE CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592)
GATE 26.0 MO CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592) 608 WEOS VALVE GATE 26.0 MO CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592) 608 WEOS VALVE GATE 2.0 MO CRANE VALVE PRODUCTS / CRANE COMPANY (A0021/00592) 608 WEOS
- Topical Report 81057' G P- U. N U 'C' L E' A R O Y S T E R C R E E K Page-20 of 24' g.
NSR GATE VALVES W/ POWER
================______________- _______________...=___________________________-- - _____________==______________
TAG NUMBER COMPCODE TYPE SIZE VALVOP MANUFACTURER NAME MODEL NUMBER
==================_______________________.____________________________________________ _________=_______=________= v===____
V-5-01ts7 VALVE GATE 6.0 MO PACIFIC VALVES / MARK CONTROLS CORPORATION (10502) 150-3-WE V-5-0166 VALVE GATE 6.0 MO PACIFIC VALVES / MARK CONTROLS' CORPORATION (10502) 150-3-WE. .
V-5-0167 VALVE GATE 6.0 MO PACIFIC VALVES / MARK CONTROLS CORPORATION (10502) 150-3-WE -
1 I
4 m._________________._________._.._______-__._____.__.___._______.___m_____________________.__e-_ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
.=-
i f f .
Topical Raport #105 R2v. O Page 21 of 24 TABLE 1
. The following power operated gate valves do not have an open safety function from a closed position at power operation or hot shutdown, therefore pressure locking and thermal binding is not a concern. .
Legends C = CLOSED 0 = OPEN NA = No TEST performed at power operation or at hot shutdown VALVE TAG NO. DESCRIPTION NORMAL SAFETY TEST POSITION FUNCTION POSITION POSITION V-17-1, 2, 3 Shutdown Cooling Pump Suction C C NA Isolation l V-17-19, 54 Shutdown Cooling Containment C C NA I 4 Isolation 1 Note 1 V-20-3,4,32,33 Core Spray Pump Suction (from O O NA Torus) Isolation Note 1 V-21-1,3,7,9 Containment Spray Pump Suction O O NA (from Torus) Isolation Note 1 V-21-75, 76 Containment Isolation for C C NA Note 2 Torus Water Cleanup V-37-9,20,31, Recirculation System Pump O O NA 42, 53 Suction V-37-10,21,32, Recirculation System Pump O O NA 43, 54 Discharge V-37-11,22,33, Recirculation System Pump O O NA 44, 55 Discharge Bypass V-5-147, 166, Reactor Building Closed 0 C NA 167 Cooling Water Containment Isolation Note 1 4
Note 1: Valves are only tested when plant is in Cold Shutdown, or system is considered inoperable.
Note 2: Valves' motor operators are not electrically connected, i
1 i
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, Topical Report #105 Rev. O Page 22 of 24 TABLE 2 The following power operated gate valves do not have an open safety function from j c closed position at power operation or at hot shutdown. These valves are fully -
stroked during testing. Therefore, pressure locking and thermal binding concerns will not be evaluated.
Legendt C = CLOSED O = OPEN
! VALVE TAG NO. DESCRIPTION NORMAL SAFETY TEST POSITION FUNCTION POSITION
- POSITION V-16-1, 14, 61 Reactor Water Cleanup O C C Containment Isolation l
V-16-2 Reactor Water Cleanup to Aux C C O Pump Containment Isolation l
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. , Topical Report #105 Rev. O I Page 23 of 24 4
TABLE 3 l i
I i
The following power operated gate valves have an open safety function from a closed ]
position during surveillance testing. Therefore, pressure locking and thermal binding concerns will be evaluated.
Legend: C = CLOSED O = OPEN VALVE TAG NO. DESCRIPTION NORMAL SAFETY TF*T POSITION FUNCTION POSITION POSITION V-14 33 Isolation Condenser Steam O C/O C Isolation V-14-36, 37 Isolation Condenser Condensate O C/O C Isolation V-20-12 Core Spray System I Pump O C/O C Discharge V-20-18 Core Spray System II Pump O C/O C Discharge V-21-13, 17 Containment Spray Recirc Valve O C/O C Ol3/028R0
. .. . . . . _ _ _ _ _ . _ . . . . _ . _ _ _ . _ _ . = _ . . _ _ _ . ~ _ . . . _ .- _. ~ . . _ _ _ _ _ . _ . . _ _ _ _ _
g i l
l, Topical Report #105 1 Rev. O Page 24 of 24
, TABLE 4 s
I l The following power operated gate valves have an open safety function from a normally a closed position at power operation and hot shutdown. Therefore, pressure locking and i thermal binding concern will be evaluated.
Legends C = CLOSED O = OPEN NA = No TEST performed at power i operation at hot shutdown VALVE TAG DESCRIPTION NORMAL SAFETY TEST NO. POSITION FUNCTION POSITION POSITION V-14-34, 35 Isolation condenser condensate C O/C O Return V-20-15, 21, Core Spray Parallel Injection C 0 0 40, 41 V-21-5, 11 Containment Spray Drywell C O O Spray Isolation V-21-15, 18 Containment Spray Torus Spray C O O 1
1 e
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