**NRC INSPECTION MANUAL** IIPB

INSPECTION PROCEDURE 62710

POWER-OPERATED GATE VALVE

PRESSURE LOCKING AND THERMAL BINDING

PROGRAM APPLICABILITY: 2515

62710‑01 INSPECTION OBJECTIVES

The objective of this procedure is to provide guidance to inspectors to
independently assess licensee conclusions regarding extent of condition
of issues, when selected, as a part of supplemental inspections using IP
95002, AInspection For One Degraded Cornerstone or Any Three White
Inputs in a Strategic Performance Area.@ The inspection procedure may
also be used when power-operated gate valve pressure-locking and
thermal-binding issues are applicable to each input contributing to a
degraded cornerstone (2 white or 1 yellow) or to address extent of
condition for any white input to the Strategic Performance Area that
results in implementation of IP 95002.

62710‑02 INSPECTION REQUIREMENTS

The scope of the inspection using this procedure should be specifically
focused on an independent extent of condition review and oversight of
licensee self-assessment consistent with the objectives of IP 95002.

The inspection plan should include one or more of the specific
requirements listed below that are appropriate to perform an independent
extent of condition review and oversight of licensee self-assessment
necessary to assess the capability of power-operated gate valves in
safety-related systems to operate under pressure-locking and
thermal-binding conditions (or avoid such conditions) during normal,
accident and abnormal conditions. The inspection may involve an in‑depth
review of calculations, analyses, diagnostic test results,
modifications, and operating procedures used to ensure that proper
operation of power-operated gate valves is not prevented by
pressure-locking and thermal-binding conditions.

Select a sample of risk-significant power-operated gate valves from more
than one system. The sample size should be appropriate for the scope of
the inspection. Considerations for the review of the licensee\'s scope
of its Generic Letter 95-07,@Pressure Locking and Thermal Binding of
Safety-Related Power-Operated Gate Valves,@ program are provided in the
Attachment 1 to this inspection procedure. Attachment 2 provides a
generic list of valves that are normally included in the scope of GL
95-07. Changes that have been made to GL 95-07 programs and
modifications involving the installation of power-operated gate valves
susceptible to pressure locking or thermal binding should be considered
during the selection of the sample of power-operated gate valves for
inspection review. These changes may involve revised design basis, plant
modifications, power uprate, revised calculations, valves added to or
removed from the program, revised safety valve setpoints, or the
incorporation of new industry guidance into the program. Power-operated
gate valve performance should be considered during valve selection. For
example, review of trend reports, nonconformance reports, Licensee Event
Reports, maintenance history or other plant documents may reveal that a
valve was subjected to pressure-locking or thermal-binding conditions.

02.01 [Program Scope]{.underline}. Review power-operated gate valve
program scope to ensure that the appropriate safety-related valves are
included and modifications to systems or valves that could have altered
the susceptibility of a power-operated gate valve to pressure locking or
thermal binding.

02.02 [Design Bases Conditions]{.underline}. Review design documents
used to determine power-operated gate valve functional requirements
during normal, accident and abnormal conditions, and susceptibility to
pressure locking or thermal binding.

02.03 [Pressure-Locking and Thermal Binding Calculations]{.underline}.
Review calculations used to demonstrate that power-operated gate valves
are capable of operating if susceptible to pressure-locking and thermal
binding conditions.

02.04 [Testing]{.underline}. Review diagnostic test results used to
support pressure-locking and thermal-binding assumptions in design
calculations or other engineering documents.

02.05 [Pressure Locking Corrective Actions]{.underline}. Review
pressure-locking corrective actions including modifications that were
implemented to eliminate the potential susceptibility of valves to
pressure lock, or to provide for the capability of the valve to operate
under such conditions, and operating procedures that contain special
instructions for valves susceptible to pressure locking.

02.06 [Thermal Binding Corrective Actions]{.underline}. Review
thermal-binding corrective actions including modifications that were
implemented to eliminate the potential susceptibility of valves to
thermally bind, or to provide for the capability of the valve to operate
under such conditions, and operating procedures that contain special
instructions for valves susceptible to thermal binding.

02.07 [Trending]{.underline}. Review trend reports, failure analysis,
corrective actions, nonconformance reports, or other plant documents
that may reveal pressure-locking or thermal-binding conditions.

02.08 [PI&R Inspection Reports]{.underline}. Review past PI&R inspection
reports on this subject. Determine if there were any significant
problems identified with pressure locking or thermal binding of valves.

62710‑03 INSPECTION GUIDANCE

[General Guidance]{.underline}

In response to the identification of plant-specific power-operated gate
valve pressure locking and thermal binding issues, the NRC staff may
determine that an inspection of the licensee=s GL 95-07 program is
appropriate using IP 62710. In planning the inspection under this
procedure, the assigned regional inspector should review the identified
power-operated gate valve pressure locking and thermal binding
performance issues. The inspector should then prepare an inspection plan
incorporating one or more of the specific inspection requirements
outlined in Section 62710-02 that the inspector considers necessary to
perform an independent extent of condition review and oversight of the
licensee self-assessment with respect to the pressure locking and
thermal binding issues identified at the plant. Based on the extent of
the selected inspection requirements, the inspector should estimate the
resources necessary to perform the inspection as discussed in Section
62710-04.

This inspection procedure is intended to assess the adequacy of
calculations, analyses, test results, operating procedures and
modification packages that are used to ensure that power-operated gate
valves are not prevented from performing their safety function by
pressure locking and thermal binding.

Pressure locking and thermal binding represent potential common-cause
failure mechanisms that can render redundant safety systems incapable of
performing their safety functions. Pressure locking occurs in
flexible-wedge and double-disk gate valves when fluid becomes
pressurized inside the valve bonnet and the actuator is not capable of
overcoming the additional thrust requirements resulting from the
differential pressure created across both valve disks by the pressurized
fluid in the valve bonnet. Thermal binding is generally associated with
solid-wedge and flexible-wedge gate valves that are closed while the
system is hot and then allowed to cool before an attempt is made to open
the valve.

On August 17, 1995, the NRC issued Generic Letter (GL) 95-07 to request
that licensees take certain 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. The NRC staff reviewed the
licensees= actions in response to GL 95-07 in a safety evaluation (SE)
for each unit. Each SE describes the actions taken by the licensee to
ensure that power-operated gate valves operate during pressure-locking
and thermal-binding conditions that were reviewed and accepted by the
NRC staff when closing GL 95-07. This safety evaluation should be
reviewed by the inspector prior to the inspection.

GL 89-10, ASafety-Related Motor-Operated Valve Testing and
Surveillance,@ requested that nuclear power plant licensees and
construction permit holders ensure the capability of motor operated
valves (MOVs) in safety-related systems to perform their intended
functions by reviewing MOV design bases, verifying MOV switch settings
initially and periodically, testing valves under design-basis conditions
where practicable, improving evaluations of MOV failures and necessary
corrective action, and trending MOV problems. GL 96-05, APeriodic
Verification of Design-Basis Capability of Safety-Related Power-Operated
Valves,@ requested each nuclear power plant licensee to establish a
program, or to ensure the effectiveness of its current program, to
verify on a periodic basis that safety-related MOVs continue to be
capable of performing their safety functions within the current
licensing bases of the facility. In most instances, risk insights were
used to develop MOV diagnostic test schedules developed in response to
GL 89-10 and GL 96-05.

The vast majority of gate valves identified as susceptible to pressure
locking and thermal binding were MOVs. Therefore, the MOV risk insights
developed in response to GL 89-10 and GL 96-05 should be considered
during the selection of sample valves to be inspected. Valves may be
risk ranked with respect to their relative importance to core-damage
frequency and other considerations added by an expert panel. The MOV
selection should include valves ranked as high risk if possible. The NRC
staff is describing its review of licensees= actions in response to GL
96-05 in an SE for each unit. Each SE notes the MOV risk-ranking
methodology that was accepted by the NRC staff when closing GL 96-05.

Several licensees did not use risk insights to rank their valves in the
development of their GL 89-10 or GL 96-05 programs. Generic MOV risk
insights for boiling water reactors (BWRs) may be obtained from BWR
Owners Group Report NEDC-32264A (Revision 2). Generic MOV risk insights
for Westinghouse plants may be obtained from Westinghouse Owners Group
(WOG) Report V-EC-1658 (Revision 1). These risk ranking approaches were
reviewed and accepted by the NRC staff in SEs dated February 27, 1997
(BWR), and April 14, 1998 (WOG).

The WOG MOV risk-ranking approach can also be used to provide insights
for ranking MOVs in Combustion Engineering and Babcock & Wilcox design
plants based on their safety significance, except that the generic list
of high risk valves in WOG Report V-EC-1658 only apply to Westinghouse
design plants.

[Specific Guidance]{.underline}

03.01 [Program Scope]{.underline}. The criteria for determining the
scope of power-operated valves for GL 95-07 are consistent with the
staff\'s acceptance of the scope of MOVs associated with GL 89-10.
Considerations for the review of the licensee\'s scope of its GL 95-07
program are provided in the Attachment 1 to this inspection procedure.
Attachment 2 provides a generic list of valves that are normally
included in the scope of GL 95-07. Since the completion of SEs for
GL 95-07, some licensees may have modified the scope of their
power-operated gate valve pressure-locking and thermal-binding programs.
Where a licensee has modified the scope of its program, the inspector
should determine whether the licensee has adequately justified the
removal of any power-operated valves from its program. Further, the
inspector should be alert for modifications to systems or valves that
could have altered the susceptibility of a power-operated gate valve to
pressure locking or thermal binding.

03.02 [Design Bases Conditions]{.underline}. The inspector should review
the appropriate design documents and operating and surveillance
procedures and verify that the licensee has considered (1) all credible
leak paths into valve bonnets; (2) external and internal conditions that
may exist or change during normal, surveillance or operating conditions
that may cause the temperature of the valve to increase; (3) the
potential for gate valves to pressure lock or thermally bind during
surveillance testing or other special tests; and (4) the potential for
valves to be closed while the system operating fluid is at a relatively
high temperature, the valve is allowed to cool, and then required to
open. For example, the fluid may enter the valve bonnet (1) during
normal open and close valve cycling; (2) when pump discharge pressurizes
a valve bonnet and the pressure becomes trapped in the bonnet after the
pump is secured; (3) if the gate valve is in a line connected to a
high-pressure system and isolated only by check valves (which may
transmit pressure even when passing leak-tightness criteria); and (4)
during a hydrostatic test of adjacent piping.

A valve bonnet that contains steam or gas is susceptible to
hydraulic-induced pressure locking. However, thermally induced pressure
locking is mitigated during conditions where the bonnet is filled with
steam or gas. The licensee should address the heat transfer to the valve
from the adjacent piping and atmosphere that can occur during accident
conditions. For example, conditions that can cause the temperature of
the valve bonnet to increase include heat from pump motors, steam driven
turbines, and high temperature fluid in adjacent piping. Normal ambient
temperature changes are not required to be considered. In some cases,
reliance on entrapped gas to limit bonnet pressure was accepted in GL
95-07 when detailed justification was provided by the licensee.

03.03 [Pressure-Locking and Thermal Binding Calculations]{.underline}
Some licensees used pressure-locking and thermal-binding methodologies
to demonstrate that valves are capable of operating under
pressure-locking and thermal-binding conditions. Calculations used to
demonstrate that selected valves are capable of operating during
pressure-locking or thermal-binding conditions should be reviewed. Motor
sizing calculations must consider degraded voltage and elevated ambient
temperature conditions. For example, the inspector should ensure that
the lowest motor terminal voltage commensurate with the design-basis
conditions has been factored into the calculation. Proper actuator
pullout efficiency and application factor must be used. The weak link
capability of the MOV should also be evaluated to ensure that the valve
or actuator is not damaged if required to operate during
pressure-locking or thermal-binding conditions. In Technical Update
98-01 and its Supplement 1, Limitorque Corporation provided updated
guidance for predicting the torque output of its ac-powered motor
actuators. In its letter dated July 17, 1998, forwarding Technical
Update 98-01, Limitorque indicates that a future technical update will
be issued to address the application of dc-powered valves.

The inspector should verify that thermal induced pressure locking
calculations assume a reasonable temperature/pressure rate increase.
NUREG-1275, AOperating Experience Feedback Report-Pressure Locking and
Thermal Binding of Gate Valves,@ states that the rate of pressure rise
can be as high as 100 psi per 1 °F temperature increase in a solid
filled bonnet for system temperature above 450 °F. For lower system
temperature (approximately 100 °F), the rate noted in NUREG-1275 is
reduced to 33 psi per 1 °F temperature rise. Testing sponsored by the
NRC that was conducted by the Idaho National Engineering and
Environmental Laboratory (INEEL) suggested that a pressure rise of 50
psi per 1 °F temperature increase was applicable. The results of this
testing are documented in NUREG/CR-6611, AResults of Pressure Locking
and Thermal Binding Tests of Gate Valves.@ These thermal induced
pressurization rates were accepted by the NRC staff in the SEs closing
GL 95-07.

Adequate bases must exist for stem factors, valve factors, and other
assumed parameters, as applicable, that are used in calculations. The
inspector should verify that the valve and stem factors used in
calculations are consistent with GL 89-10 program values. The following
is a list of the pressure-locking methodologies most often used by
licensees in their GL 95-07 submittals to demonstrate that valves are
capable of operating under pressure-locking conditions.

a.  A pressure-locking methodology developed by Commonwealth Edison
    Company (ComEd) was used for flexible wedge gate valves. The margins
    along with diagnostic equipment accuracy and methodology limitations
    are defined in a letter from ComEd to the NRC dated May 29, 1998.
    The use of the ComEd pressure locking methodology is acceptable
    provided these margins, diagnostic equipment accuracy requirements
    and methodology limitations are incorporated into the
    pressure-locking calculations as specified in the applicable GL
    95-07 SE. The NRR Mechanical and Civil Engineering Branch (EMEB)
    developed a computer program to assist inspectors in assessing the
    capability of flexible gate valves to open during pressure-locking
    conditions using the ComEd thrust prediction pressure-locking
    methodology. Contact EMEB or the regional motor operated valve
    inspector for further information regarding use of the computer
    program.

b.  A modified industry gate valve thrust equation was used to predict
    the thrust required to open flexible wedge gate valves during
    pressure locking conditions. Pressure locking tests sponsored by the
    NRC were conducted by the INEEL on a flexible wedge gate valve. The
    results of this testing are documented in NUREG/CR-6611. Test data
    demonstrated that the modified industry gate valve calculation
    conservatively estimated the thrust required to open a
    pressure-locked flexible wedge gate valve.

c.  A modified industry gate valve thrust equation was used to predict
    the thrust required to open double disk gate valves during
    pressure-locking conditions. Pressure-locking tests sponsored by the
    NRC were conducted by INEEL on a double disk gate valve. The results
    of this testing are documented in NUREG/CR-6611. Test data
    demonstrated that the modified industry gate valve calculation
    underestimated the thrust required to open a pressure-locked double
    disk gate valve; however, the results of the calculation properly
    trended with actual test results. Sizing the power actuator to
    satisfy the modified industry gate valve thrust equation provides
    reasonable assurance that flexible wedge gate valves susceptible to
    pressure locking are capable of performing their intended
    safety-related function provided that the margin between predicted
    pressure-locking thrust and actuator capability is equal to or
    exceeds approximately 40 percent. The licensee should provide
    additional justification if it proposes a margin less than
    approximately 40 percent.

This is not a complete list of pressure-locking methodologies used by
licensees to demonstrate that valves are capable of operating during
pressure-locking conditions. Some licensees developed a site-specific
pressure locking or thermal binding thrust prediction methodology to
demonstrate that valves are capable of opening under pressure-locking or
thermal-binding conditions. The conditions and limitations associated
with the use of the individual methodology are discussed in the
site-specific GL 95-07 SE. In instances where a licensee developed and
used a site-specific methodology (methodology was not described in
section 03.03a, b or c in this inspection procedure), the inspector
should review the test data used to ensure that the methodology
accurately predicts the thrust required for the valve to open during
pressure-locking or thermal-binding conditions. The inspector should (1)
verify test equipment is setup and calibrated in accordance with vendor
recommendations; (2) verify qualification of test personnel; (3)
determine test equipment inaccuracies and test data accuracy; and (4)
verify that the methodology accurately predicts the thrust (torque)
required to open the pressure-locked or thermally-bound valve.

Following the initial verification of valve capability under
design-basis conditions, the valve settings will need to be re-verified
if the valve is replaced (which would constitute the need for a complete
demonstration of design-basis capability), modified, or overhauled to
the extent that the licensee considers that the existing test results
are not representative of the valve in its modified configuration.
Because of the interrelationship of various operating parameters, the
performance of the valve can be affected by routine maintenance work,
such as valve packing adjustments.

03.04 [Testing]{.underline}. The inspector should review the diagnostic
test results used to support pressure-locking and thermal-binding
assumptions in design calculations or other engineering documents. The
assumptions include valve factors and stem factors for MOVs which were
established under the GL 89-10 program and periodically verified under
the GL 96-05 program. Diagnostic testing to support MOV pressure-locking
and thermal-binding assumptions should be consistent with the diagnostic
testing methods justified under the GL 89-10 and GL 96-05 programs.

03.05 [Pressure Locking Corrective Actions]{.underline}. The inspector
should review the corrective actions performed in response to GL 95-07
for the sampled valves. The following are examples of corrective actions
to prevent or overcome pressure locking accepted in GL 95-07 SEs.

a.  [Procedures]{.underline}

    1.  Procedures were modified to cycle valves following evolutions
        that could potentially create a pressure-locking condition.

    2.  Procedures were revised to minimize the time that pumps could be
        operated at minimum flow conditions if temperature of the system
        increased due to operation of the pumps at minimum flow.

    3.  The bonnet of the valve was aligned to the reactor side piping
        on valves equipped with a body drain.

    4.  The position of the valve was changed from closed to open or
        procedures were revised to not require that the valve be opened
        during pressure-locking conditions.

    5.  The containment sump suction piping was filled with water or
        maintained in a dry-lay condition to prevent the temperature of
        the valves from increasing during accident conditions.

    6.  Procedures were revised to prevent one train from being
        inadvertently pressurized when testing the other train.

    7.  The suction of one train of residual heat removal was aligned to
        the refueling water storage tank when the other train of
        residual heat removal was aligned for shutdown cooling.

b.  [Modifications]{.underline}

    1.  Actuator control logic was changed to utilize the limit switch
        to minimize travel of the disk into the seat. Procedures were
        revised to periodically review diagnostic test data to ensure
        that disk travel was minimized.

    2.  Valves were modified to eliminate the potential for pressure
        locking by drilling a hole in the high pressure side of the
        valve disk or installation of a bonnet pressure equalization
        line.

    3.  Valves were replaced with valves not susceptible to pressure
        locking.

    4.  Valve bonnets were equipped with a relief valve or blowout plug
        to limit the pressure in the bonnet and a pressure locking
        analytical method used to calculate the thrust (torque) required
        to open the valve during pressure-locking conditions below the
        relief valve or blowout plug setpoint.

    5.  Valve bonnets were equipped with an accumulator to limit the
        pressure in the bonnet and a pressure locking analytical method
        used to calculate the thrust (torque) required to open the valve
        during pressure-locking conditions below the maximum accumulator
        pressure.

    6.  A bonnet vent with a manual valve was installed and procedures
        were revised to cycle the bonnet vent valve prior to opening the
        valve during pressure-locking conditions.

    7.  The actuator was modified or replaced with a larger actuator to
        increase thrust (torque) output to meet thrust prediction
        pressure-locking methodology requirements.

    8.  Insulation was installed on the valve body and bonnet to
        minimize the heat transfer to the bonnet during conditions when
        the ambient temperature could increase during a design basis
        accident.

c.  [Analyses/Calculations]{.underline}

    1.  Some licensees relied on pump discharge pressure to equalize
        pressure in the bonnet of a valve that is susceptible to
        pressure locking. As a result, the MOV may operate at locked
        rotor. The NRC staff accepted operation of actuators for
        approximately 1 second at locked-rotor conditions because
        testing performed by INEEL (NUREG/CR-6478) demonstrates that the
        capability of the actuator does not degrade over this short time
        period.

    2.  The ComEd pressure-locking thrust prediction methodology was
        used to demonstrate that flexible wedge gate valves would
        operate during pressure‑locking conditions.

    3.  A modified industry gate valve thrust equation was used to
        demonstrate that double disk gate valves would operate during
        pressure‑locking conditions.

    4.  A modified industry gate valve thrust equation was used to
        demonstrate that flexible wedge gate valves would operate during
        pressure‑locking conditions.

    5.  In cases where 12 or more hours elapse between pressurizing the
        valve bonnet and opening the valve, leakage was credited to vent
        the valve bonnet provided that the temperature of the valve did
        not increase over the 12-hour period. In one case, valve leakage
        was credited to vent the bonnet of each of the unit=s reactor
        coolant system hot leg injection valves. There were six hot leg
        injection valves and six redundant hot leg flow paths in each
        unit and one hot leg injection valve was required to be opened
        5.5 hours or more after a loss of coolant accident. The basis
        for accepting this analysis was that the probability of a loss
        of coolant accident combined with the failure of all six hot leg
        injection valves to open due to pressure locking is exceedingly
        low. The results of valve seat leakage test performed by several
        licensees and INEEL (NUREG/CR-6611) demonstrate that valve
        leakage is probable when pressure-locking conditions exist;
        however, the specific leakage rates that were obtained during
        the tests were inconclusive.

    6.  Heat transfer calculations were used to demonstrate that the
        temperature of valves would not increase during accident
        conditions. Normal ambient temperature changes were not required
        to be considered.

03.06 [Thermal Binding Corrective Actions]{.underline}. The inspector
should review the corrective actions performed in response to GL 95-07
for the sampled valves. The following are examples of accepted
corrective actions to prevent or overcome thermal binding.

a.  [Procedures]{.underline}

    1.  Technical Specifications were changed to require that valves be
        declared inoperable and the appropriate Technical Specification
        action statement entered whenever the valves are closed while
        the system is hot and then allowed to cool before an attempt is
        made to open the valves.

    2.  Procedures were modified to cycle valves following evolutions
        that could potentially create a thermal-binding condition.

    3.  Procedures were revised to shut the valve prior to increasing
        the temperature of the valve.

b.  [Modifications]{.underline}

    1.  Valves were replaced with valves not susceptible to thermal
        binding.

    2.  Valves equipped with spring-compensating actuators, position
        seated, and/or set up with minimal unwedging thrust to reduce
        the potential for thermal binding.

c.  [Analyses/Calculations]{.underline}

    1.  When evaluating whether flexible and solid-wedge gate valves
        were susceptible to thermal binding, licensees assumed that
        thermal binding would not occur below specific temperature
        thresholds. These assumptions were based on industry experience.

    2.  Several thermal-binding methodologies were developed and used to
        demonstrate that valves were capable of operating during
        thermal-binding conditions. Test data that quantified the
        magnitude of the thermal binding effect were used to validate
        the thermal-binding methodology.

    3.  Diagnostic testing performed during thermal-binding conditions
        demonstrated that a valve was not susceptible to thermal binding
        at current settings.

    4.  Operational history was used to demonstrate that valves were not
        susceptible to thermal binding.

03.07 [Trending]{.underline}. The inspector should review the adequacy
of the licensee\'s analyses of power-operated gate failures that may be
attributed to pressure locking or thermal binding. The inspector should
review recent failures and the resulting corrective action. The
licensee=s failure analysis should include the results and history of
each as-found deteriorated condition, malfunction, test, inspection,
analysis, repair, or alteration.

03.08 [PI&R Inspection Reports]{.underline}. No specific guidance.

62710-04 RESOURCES

This inspection procedure provides guidance that could be used to assess
the entire GL 95-07 program. However, since the scope of the inspection
is focused on an independent extent of condition review and oversight of
licensee self-assessment and may be limited to specific inspection
requirements identified in Section 62710-02, it is estimated that it may
take an inspector a minimum of 4 hours to accomplish. If the nature of
the problems prompting the inspection are extensive requiring a more
broad review, then it may take up to 30 hours to accomplish the
inspection.

Other factors that affect the amount of time required to complete the
inspection are the knowledge and experience of the inspector(s) and the
number of safety-related power-operated gate valves in each unit. It is
recommended that inspector(s) knowledgeable of GL 89-10, GL 95-07, and
GL 96-05 recommendations and power-operated gate valve mechanical and
electrical characteristics perform the inspection. The majority of
power-operated gate valves that were identified to be susceptible
pressure locking and thermal binding in GL 95-07 submittals were MOVs.
Some early-vintage units may have fewer safety-related power-operated
gate valves than later-vintage units. The number of safety-related
power-operated gate valves should be considered when determining the
amount of time needed to accomplish the inspection.

62710-05 REFERENCES

GL 89-10, ASafety-Related Motor-Operated Valve Testing and Surveillance@

GL 96-05, APeriodic Verification of Design-Basis Capability of
Safety-Related Motor-Operated Valves@

GL 95-07, APressure Locking and Thermal Binding of Safety-Related
Power-Operated Gate Valves@

BWR Owners Group (BWROG) Report NEDC-32264A (Revision 2), AApplication
of Probabilistic Safety Assessment to Generic Letter 89-10
Implementation@

Westinghouse Owners Group (WOG) Report V-EC-1658 (Revision 1), ARisk
Ranking Approach for Motor-Operated Valves in Response to Generic Letter
96-05@

END

Attachments:

1\. Considerations in Reviewing Licensee Scope of Generic Letter 95-07
Programs.

2\. Generic List of Valves Susceptible to Pressure Locking and Thermal
Binding.

Attachment 1

**CONSIDERATIONS IN REVIEWING LICENSEE SCOPE OF GL 95-07 PROGRAM**

1.  The scope of the program extends to safety-related power-operated
    valves as defined in the NRC regulations. In GL 95-07, the staff
    requests licensees to determine the design basis for the operation
    of each safety-related power-operated valve including the maximum
    pressure and temperature conditions expected during normal
    operations and abnormal events, to the extent that these valve
    operations and events are included in the existing approved design
    basis.

2.  Safety-related power-operated valves that are always in their safety
    position, or would have no affect on the operation of the safety
    train if placed in the non-safety position, can be removed from the
    GL 95-07 program.

3.  Section 3.1.2 of NUREG-1482, \"Guidelines for Inservice Testing at
    Nuclear Power Plants,\" issued by GL 89-04 (Supplement 1),
    \"Guidance on Developing Acceptable Inservice Testing Programs,\"
    dated April 4, 1995, discusses the capability of plant components
    and surveillance testing. In this regard, safety-related
    power-operated valves that are placed in a position that prevents
    the safety-related system (or train) from performing its safety
    function must be capable of returning to their safety position, or
    the system (or train) must be declared inoperable and the
    appropriate plant technical specifications followed.

4.  In the second footnote in GL 89-10, the staff states that
    design-basis events are defined as conditions of normal operation,
    including anticipated operational occurrences, design-basis
    accidents, external events, and natural phenomena for which the
    plant must be designed to ensure the function delineated as
    \"safety-related\" can be performed. The staff further states in the
    footnote that the design bases for each plant are those documented
    in pertinent licensee submittals, such as the final safety analysis
    report. In Bulletin 85-03, the staff requested Boiling Water Reactor
    (BWR) plants to ensure that valves in the Reactor Core Isolation
    Cooling system can perform their safety function.

5.  Supplements 4 and 7 to GL 89-10 removed the recommendation that
    licensees of BWR and pressurized water reactor nuclear plants,
    respectively, consider inadvertent mispositioning of valves as part
    of their GL 89-10 programs.

6.  The residual heat removal pump hot-leg injection valve(s) was (were)
    not in the scope of GL 95-07 if the final safety analysis report
    (FSAR) accident analysis did not credit the residual heat removal
    pumps for providing hot-leg injection. The pressurizer
    power-operated relief valve block valve was not in the scope of GL
    95-07 if technical specifications allowed the unit to operate
    indefinitely with the pressurizer power-operated relief block valve
    shut and deenergized. Emergency core cooling system valves for modes
    other than criticality and recovery from an inadvertent reactor trip
    were not in the scope of GL 95-07 if technical specifications
    required that the emergency core cooling systems be operable for the
    criticality and recovery from an inadvertent reactor trip.

7.  Licensees may rely on analysis results for each design-basis event
    and each system\'s required capability to satisfy event acceptance
    limits provided in the FSAR where the licensee can demonstrate that
    the information in the updated FSAR is consistent with the licensing
    basis of the facility.

8.  Licensees are required to meet the single failure criterion in the
    NRC regulations. Other criteria may also apply at the same time
    (e.g., loss of offsite power). Further, safety systems are required
    to meet the redundancy provisions of Appendix A to 10 CFR Part 50.
    The consideration of the single failure criterion as applied to
    anticipated operational transients should be consistent with the
    staff\'s licensing review for the individual facility.

9.  The safe shutdown licensing basis for each facility is defined in
    licensing documents. Valves that are operated during conditions
    below the safe shutdown licensing basis are not required to be in
    the scope of the GL 95-07 program provided that the licensee does
    not have any other commitments that the MOV must operate during
    certain conditions. For example, if the safe shutdown licensing
    basis is Hot Shutdown, valves that are operated during conditions
    below Hot Shutdown are not required to be in the scope of the
    program.

END

Attachment 2

**GENERIC LIST OF VALVES SUSCEPTIBLE TO**

**PRESSURE LOCKING AND THERMAL BINDING**

**BABCOCK & WILCOX-DESIGN PLANTS**

[Valve Susceptible to Pressure Locking]{.underline}

Decay Heat Cooler Discharge to Makeup Suction

Decay Heat Drop Line Isolation

Decay Heat Injection

Decay Heat Supply to High Pressure Injection (HPI) Pump Suction

Emergency Feedwater (EFW) Header Cross Connect

EFW Pump Discharge

EFW Pump Service Water Suction

EFW Turbine Steam Admission

HPI Pump Discharge Cross Connect

Low Pressure Injection (LPI) Header Isolation to HPI

LPI/Decay Heat Loop Isolation

LPI Isolation

LPI Reactor Building Isolation

LPI Return from Reactor Coolant System (RCS)

Post Loss of Coolant Accident Boron Dilution to the Emergency Sump

Pressurizer Electromatic Relief Valve Isolation

Pressurizer Power-Operated Relief Valve (PORV) Block

RCS Return from Letdown Line

Reactor Building Cooling Unit Inlet Isolation

Sodium Hydroxide Tank Suction

Spent Fuel Pool to RCS Makeup Pump Suction Block

[Valves Susceptible to Thermal Binding]{.underline}

EFW Pump Injection

EFW Turbine Steam Inlet

LPI Injection

Pressurizer Electromatic Relief Valve Isolation

Pressurizer Sample Isolation

Pressurizer Vent Stop

Pressurizer PORV Block

Reactor Building Sump Isolation

Safety Injection Pump Suction

**COMBUSTION ENGINEERING-DESIGN PLANTS**

[Valves Susceptible to Pressure Locking]{.underline}

Auxiliary Feed Water (AFW) Pump Discharge

AFW Pump Turbine Steam Supply

Boric Acid Gravity Feed Isolation

Boric Acid Makeup (BAMU) Pump to Charging Pump Suction Control Valve

BAMU Tank Gravity Feed to Charging Pump

BAMU Tank to Charging Pump Suction Header Control Valve

Containment Spray Header Isolation

Containment Spray Shutdown Cooling Heat Exchanger Bypass

Containment Sump Header Isolation

High Pressure Safety Injection Long Term Loop Recirculation

Low Temperature Overpressure Relief Isolation

Pressurizer Emergency Core Cooling Vent

Pressurizer Power-Operated Relief Valve (PORV) Block

Refueling Water Storage Tank to Charging Pump Suction

Safety Injection Pump Recirculation to Refueling Water Storage Tank

Service Water to Emergency Feedwater Pump Isolation

Shutdown Cooling Cross Tie

Shutdown Cooling Heat Exchanger Inlet

Shutdown Cooling Heat Exchanger Outlet

Shutdown Cooling Hot Leg Suction

Shutdown Cooling to Low Pressure Safety Injection Pump Suction

[Valves Susceptible to Thermal Binding]{.underline}

Boric Acid Pump to Charging Pump Suction

Boric Acid Storage Tank Outlet Isolation

Charging Pump Suction Header and Boric Acid Supply

Emergency Feedwater Injection

Emergency Feedwater Turbine Steam Inlet

High Pressure Safety Injection/Charging Cross Tie

Pressurizer PORV Block

Shutdown Cooling Heat Exchanger Isolation

Shutdown Cooling Hot Leg Suction

**WESTINGHOUSE-DESIGN PLANTS**

[Valves Susceptible to Pressure Locking]{.underline}

Alternate Charging Isolation

Auxiliary Feedwater Pump Discharge to Steam Generators

Boric Acid Tank Gravity Boration

Boron Injection Tank Inlet

Boron Injection Tank Outlet

Component Cooling Water from Residual Heat Removal (RHR) Heat Exchangers

Containment Spray Pump Discharge

Containment Sump to RHR Pump Suction

Diesel Generator Lube Oil Filter Bypass

High Head Safety Injection (SI) Pump to Cold Leg

Low Head SI Pump Suction

Main Steam to Turbine Driven Auxiliary Feedwater Pump

Normal Charging Isolation

Pressurizer Power Operated Relief Valve (PORV) Block

Quench Spray Pump Discharge

Reactor Building Cooling Unit Outlet Isolation

Refueling Water Storage Tank (RWST) to Charging Pump Suction

RHR Cross-Tie Isolation

RHR Heat Exchanger Outlet

RHR Heat Exchanger Outlet to Containment Spray Header

RHR Pump Suction from the RWST

RHR to Hot Leg Injection

RHR to Reactor Vessel Deluge

RHR to SI/Charging Suction

Recirculation Spray System (RSS) to RHR Cross Connect

RSS Cooling Pump Discharge Isolation

RSS Pump Discharge Isolation

RSS to SI

SI Pump Hot Leg Isolation

SI Pump Discharge Isolation

SI to Charging System

Service Water Supply to Standby Auxiliary Feedwater Pumps

Steam Generator Pressure Relief Isolation

Sodium Hydroxide to Reactor Building Spray Pump Suction

Volume Control Tank (VCT) Outlet

VCT Outlet

[Valves Susceptible to Thermal Binding]{.underline}

Low Head SI Cold Leg Isolation

Pressurizer PORV Block

Reactor Coolant System to RHR Pump Suction

RHR Minimum Flow Control

Steam Generator PORV Block

**GENERAL ELECTRIC-DESIGN PLANTS**

[Valves Susceptible to Pressure Locking]{.underline}

Containment Spray Isolation

Core Spray Injection

Drywell Spray

Essential Low Pressure Coolant Injection Inverter Room Cooler Inlet

High Pressure Coolant Injection (HPCI) Isolation

HPCI Turbine Steam Admission

High Pressure Core Spray (HPCS) Pump Minimum Flow

HPCS Pump Suction from Suppression Pool

Isolation Condenser Condensate Return

Low Head Safety Injection (SI) Cold Leg Isolation

Low Pressure Core Spray Pump Minimum Flow Bypass Isolation

Main Steam Drain Isolation

Main Steam Isolation Valve Leakage Control

Reactor Core Isolation Cooling (RCIC) Injection

RCIC Pump Suppression Pool Suction

RCIC Steam Exhaust to Suppression Pool

RCIC Steam Supply Isolation

Reactor Water Clean Up Isolation

Residual Heat Removal (RHR) Containment Spray Shutoff

RHR Heat Exchanger Inlet

RHR Heat Exchanger Outlet

RHR Loop Isolation

RHR Low Pressure Coolant Injection

RHR Pump Minimum Flow

RHR Pump Suction from Suppression Pool

RHR Pump Torus Suction

RHR Test Return to Suppression Pool

RHR Torus Cooling/Spray Block

Service Water (SW) from RHR Heat Exchanger

SW/RHR Containment Flooding Cross Tie

SW Return Isolation from Diesel Generator Cooler

SW to Control Room Chiller Isolation

SW to Spent Fuel Cooling Heat Exchanger Isolation

Shutdown Cooling Hot Leg Suction

[Valves Susceptible to Thermal Binding]{.underline}

HPCI Injection

HPCI Turbine Steam Admission

Isolation Condenser Condensate Return Isolation

RCIC Injection

RHR Heat Exchanger Inlet and Outlet

RHR Minimum Flow Bypass

END