Federal Register / Vol. 60, No. 58 / Monday, March 27, 1995 / Notices 15799

Street, NW (Lower Level), Washington,

DC 20555–0001.

Comments and questions can be

directed by mail to the OMB reviewer:

Troy Hillier, Office of Information and

Regulatory Affairs (3150–0136), NEOB–

10202, Office of Management and

Budget, Washington, DC 20503.

Comments can also be submitted by

telephone at (202) 395–3084. The NRC

Clearance Officer is Brenda Jo. Shelton,

(301) 415–7233.

Dated at Rockville, Md., this 21st day of

March, 1995.

For the Nuclear Regulatory Commission.

Gerald F. Cranford,

Designated Senior Official for Information

Resources Management.

[FR Doc. 95–7434 Filed 3–24–95; 8:45 am]

BILLING CODE 7590–01–M

[Docket Nos. 50–254 and 50–265]

Commonwealth Edison Co. and IowaIllinois Gas and Electric Co., Quad

Cities Nuclear Power Station, Units 1

and 2; Environmental Assessment and

Finding of No Significant Impact

The U.S. Nuclear Regulatory

Commission (the Commission) is

considering issuance of an amendment

to Facility Operating License Nos. DPR–

29 and DPR–30, issued to

Commonwealth Edison Company

(ComEd, the licensee) for operation and

Iowa-Illinois Gas and Electric Company

(IIGEC) for possession of the Quad Cities

Nuclear Power Station, Units 1 and 2,

located in Rock Island County, Illinois.

Environmental Assessment

Identification of the Proposed Action

The proposed action would revise the

operating license to reflect the transfer

of IIGEC’s 25 percent ownership in

Quad Cities, Units 1 and 2, through the

merger of IIGEC, MidAmerican Energy

Company (MidAmerican), Midwest

Power Systems Inc. and Midwest

Resources Inc., with MidAmerican as

the surviving entity from the merger.

Quad Cities is operated by ComEd on

behalf of IIGEC. Commonwealth Edison

Company, alone, is licensed to operate

Quad Cities, Units 1 and 2. The

proposed action is in accordance with

ComEd’s application dated February 23,

1995.

The Need for the Proposed Action

The proposed action is required to

reflect the ownership change discussed

above. The amendment reflecting the

transfer of IIGEC’s interest in the license

will have minimal impact on the

operation of the facility by ComEd. The

transfer and amendment will not affect

the facility’s Technical Specifications,

license conditions, or the organization

and practices of ComEd.

Environmental Impacts of the Proposed

Action

The Commission has completed its

evaluation of the proposed license

amendment and concludes that there

will be no changes to Quad Cities, Units

1 and 2, or the environment as a result

of this action. The transfer of IIGEC’s

possession-only interest in the license

and the associated license amendment

will not affect the numbers,

qualifications, or organizational

affiliation of the personnel who operate

the facility, as ComEd will remain the

holder of the operating license and

continue to be responsible for the

operation of Quad Cities, Units 1 and 2.

The Commission has evaluated the

environmental impact of the proposed

action and has determined that the

probability or consequences of accidents

would not be increased by the transfer

of ownership, and that post-accident

radiological releases would not be

greater than previously determined.

Further, the Commission has

determined that the transfer of

ownership would not affect routine

radiological plant effluents and would

not increase occupational radiological

exposure. Accordingly, the Commission

concludes that there are no significant

radiological environmental impacts

associated with the proposed action.

With regard to potential nonradiological impacts, the transfer of

ownership would not affect

nonradiological plant effluents and

would have no other environmental

impact. Therefore, the Commission

concludes that there are no significant

nonradiological environmental impacts

associated with the proposed action.

Alternative to the Proposed Action

Since the Commission has concluded

that the environmental effects of the

proposed action are not significant, any

alternative with equal or greater

environmental impact need not be

evaluated. The principal alternative

would be to deny the requested

approval. Denial of the application

would result in no change in current

environmental impacts. The

environmental impacts of the proposed

action and the alternative action are

identical.

Alternative Use of Resources

This action does not involve the use

of resources not previously considered

in the Final Environmental Statement

related to operation of Quad Cities

Nuclear Power Station, Units 1 and 2,

dated September 1972.

Agencies and Persons Consulted

The NRC staff reviewed the licensee’s

request and consulted with the Illinois

State official regarding the

environmental impact of the proposed

action. The State official had no

comments.

Finding of No Significant Impact

Based upon the foregoing

environmental assessment, the

Commission concludes that the

proposed action will not have a

significant effect on the quality of the

human environment. Accordingly, the

Commission has determined not to

prepare an environmental impact

statement for the proposed license

amendment.

For further details with respect to this

action, see the licensee’s submittal

dated February 23, 1995, which is

available for public inspection at the

Commission’s Public Document Room,

the Gelman Building, 2120 L Street,

NW, Washington, DC, and at the local

public document room located at the

Dixon Public Library, 221 Hennepin

Avenue, Dixon, Illinois.

Dated at Rockville, Md., this 21st day of

March 1995.

For the Nuclear Regulatory Commission.

Robert A. Capra,

Director, Project Directorate III–2, Division

of Reactor Projects—III/IV, Office of Nuclear

Reactor Regulation.

[FR Doc. 95–7435 Filed 3–24–95; 8:45 am]

BILLING CODE 7590–01–M

Proposed Generic Letter; Pressure

Locking and Thermal Binding of

Safety-Related Power-Operated Gate

Valves

AGENCY: Nuclear Regulatory

Commission.

ACTION: Notice of issuance.

SUMMARY: The Nuclear Regulatory

Commission (NRC) is proposing to issue

a generic letter regarding pressure

locking and thermal binding of safetyrelated power-operated gate valves. This

proposed generic letter is intended to

ensure that addressees have performed

or will perform evaluations, and as

appropriate, analyses and/or corrective

actions to ensure that safety-related

power-operated gate valves that may be

susceptible to pressure locking or

thermal binding are capable of

performing their required safety

functions. The NRC is seeking comment

from interested parties regarding both

the technical and regulatory aspects of
15800 Federal Register / Vol. 60, No. 58 / Monday, March 27, 1995 / Notices

the proposed generic letter presented

under the Supplementary Information

heading. This generic letter and

supporting documentation were

discussed in meeting number 268 of the

Committee to Review Generic

Requirements (CRGR) on January 24,

1995. The staff incorporated the changes

requested by CRGR plus information

concerning two recent events and

obtained CRGR endorsement. The

relevant information that was sent to the

CRGR to support their review of the

proposed generic letter will be placed in

the Public Document Room. The NRC

will consider comments received from

interested parties in the final evaluation

of the proposed generic letter. The

NRC’s final evaluation will include a

review of the technical position and,

when appropriate, an analysis of the

value/impact on licensees. Should this

generic letter be issued by the NRC, it

will become available for public

inspection in the Public Document

Room.

DATES: Comment period expires April

26, 1995. Comments submitted after this

date will be considered if it is practical

to do so, but assurance of consideration

cannot be given except for comments

received on or before this date.

ADDRESSES: Submit written comments

to Chief, Rules Review and Directives

Branch, U.S. Nuclear Regulatory

Commission, Washington, DC 20555.

Written comments may also be

delivered to 11545 Rockville Pike,

Rockville, Maryland, from 7:30 am to

4:15 pm, Federal workdays. Copies of

written comments received may be

examined at the NRC Public Document

Room, 2120 L Street, NW. (Lower

Level), Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Thomas G. Scarbrough, (301) 415–2794.

SUPPLEMENTARY INFORMATION: NRC

Generic Letter 95–XX: Pressure Locking

and Thermal Binding of Safety-Related

Power-Operated Gate Valves.

Addresses

All holders of operating licenses or

construction permits for nuclear power

reactors.

Purpose

The U.S. Nuclear Regulatory

Commission (NRC) is issuing this

generic letter to request that addressees

perform, or confirm that they already

have performed, (1) evaluations of

operational configurations of safetyrelated power-operated (including

motor, air, and hydraulic-operated) gate

valves for susceptibility to pressure

locking and thermal binding, and (2)

further analyses, and any needed

corrective actions, to ensure that safetyrelated power-operated gate valves that

are susceptible to pressure locking or

thermal binding are capable of

performing their required safety

functions.

NRC previously provided guidance on

an acceptable approach for addressing

pressure locking and thermal binding of

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. This letter

confirms (as was indicated earlier in

Supplement 6) that licensees are

expected under existing regulations to

take actions to ensure that safety-related

power-operated gate valves susceptible

to pressure locking or thermal binding

are capable of performing their required

safety functions. The guidance in

Attachment 1 to this letter is derived

directly from (and is intended to be the

same as) the guidance provided in

Enclosure 1 to GL 89–10, Supplement 6;

except, in this generic letter, (1) the

guidance is being issued as an approved

generic NRC staff position for

implementation by licensees who have

not already satisfactorily addressed

pressure locking and thermal binding of

MOVs by implementing the guidance in

Supplement 6 (or equivalent industry

methods); and (2) the guidance is also

intended for adaptation and

implementation by all licensees, to

address the pressure-locking and

thermal-binding phenomena in other

types of power-operated (i.e., air and

hydraulic-operated) gate valves, as well

as MOVs. Finally, for both MOVs and

other power-operated valves, this letter

requires that licensees submit for staff

review summary information regarding

any actions taken to ensure that valves

susceptible to pressure locking or

thermal binding are capable of

performing their required safety

functions, including (a) actions taken by

licensees on their own volition to

implement the guidance provided in

Supplement 6 (or equivalent industry

methods), as well as (b) actions taken in

response to this letter. (No response was

required from licensees in Supplement

6 to GL 89–10 regarding pressure

locking and thermal binding.)

In this generic letter, the NRC staff is

requesting a preliminary evaluation of

pressure locking and thermal binding of

safety-related power-operated gate

valves, and, subsequently, a more

detailed evaluation and resolution of the

issue.

Background

The NRC staff and the nuclear

industry have been aware of disc

binding problems of gate valves for

many years. The industry has issued

several event reports describing failure

of safety-related gate valves to operate

due to pressure locking or thermal

binding of the valve discs. Several

generic industry communications have

given guidance for both identifying

susceptible valves and performing

appropriate preventive and corrective

measures. Despite industry awareness of

the problem, pressure locking and

thermal binding events continue to

occur. In addition to events at U.S.

nuclear power plants, French

experience with pressure locking events

was recently documented in NUREG/

CP–0137 (July 1994), ‘‘Proceedings of

the Third NRC/ASME Symposium on

Valve and Pump Testing.’’

In GL 89–10 (June 28, 1989), the staff

asked holders of operating licenses and

construction permits to provide

additional assurance of the capability of

safety-related MOVs and certain other

MOVs in safety-related systems to

perform their safety-related functions by

reviewing MOV design bases, verifying

MOV switch settings initially and

periodically, testing MOVs under

design-basis conditions where

practicable, improving evaluations of

MOV failures and necessary corrective

action, and trending MOV problems. In

Enclosure 1 to Supplement 6 to GL 89–

10 (March 8, 1994), the NRC staff

described one acceptable approach for

licensees to address pressure locking

and thermal binding of motor-operated

gate valves.

In March 1993, the NRC issued

NUREG–1275, Volume 9, ‘‘Pressure

Locking and Thermal Binding of Gate

Valves.’’ This NUREG give the history of

pressure locking and thermal binding

events, describes the phenomena,

discusses the consequences of locking

or binding on valve functionality,

summarizes preventive measures, and

assesses the safety significance of the

phenomena. Pressure locking or thermal

binding can cause a power-operated

valve to fail to open, resulting in an

inability of the associated safety train or

system to perform its safety function.

Pressure locking and thermal binding

represent potential common-cause

failure modes that can render redundant

trains of certain safety-related systems

or multiple safety systems incapable of

performing their safety function. Such

failures may not be self-revealing

through existing surveillance tests or

normal operating cycles.
Federal Register / Vol. 60, No. 58 / Monday, March 27, 1995 / Notices 15801

Description of Circumstances

After issuing Volume 9 of NUREG–

1275, the NRC staff discussed pressure

locking and thermal binding with

several licenses (1) to gather information

on the technical issues related to generic

and plant-specific valve and system

characteristics, and (2) to determine the

implementation status of prior industry

guidance for identification of

susceptible valves and application of

preventive and corrective measures.

NRC surveys indicated that some

licensees have performed multiple

reviews of pressure locking and thermal

binding. However, the staff found only

limited instances of valves being

modified to alleviate the effects of

pressure locking and thermal binding.

In Enclosure 1 to Supplement 6 of GL

89–10, the NRC staff reminded licensees

that they are expected under existing

regulations to take actions to ensure that

safety-related power-operated gate

valves susceptible to pressure locking or

thermal binding are capable of

performing their required safety

functions, and described an acceptable

approach for licensees and permit

holders to address pressure locking and

thermal binding of motor-operated gate

valves as part of their GL 89–10

programs. The information on pressure

locking and thermal binding of motoroperated gate valves provided in

Enclosure 1 to Supplement 6 of GL 89–

10 was intended as timely notification

of operating experience feedback.

During inspections of GL 89–10

programs, the staff found the actions

taken by licensees to address pressure

locking and thermal binding of motoroperated gate valves to be varied.

Although many licensees had

conducted some level of review of the

potential for pressure locking and

thermal binding of their motor-operated

gate valves, few licensees had either (1)

thoroughly evaluated the capability of

the motor actuators to overcome the

phenomena, or (2) taken corrective

action to prevent the phenomena as

discussed in Supplement 6. In view of

these inspection results, the NRC staff

has determined that further action (i.e.,

this generic letter) is now warranted to

ensure that safety-related poweroperated gate valves susceptible to

pressure locking or thermal binding are

capable of performing their required

safety functions.

Most licensees are nearing completion

of their GL 89–10 programs. In meetings

with industry representatives and

licensees, the staff stated that, during its

closure review, it will assess the

progress being made by licensees in

addressing pressure locking and thermal

binding of motor-operated gate valves.

The staff also stated that licensees need

not complete their response to the

pressure locking and thermal binding

issue at the time that the verification of

the design-basis capability of MOVs

within the scope of GL 89–10 is

completed because the staff would

evaluate the acceptability of addressee

resolution to pressure locking and

thermal finding of all safety-related

power-operated gate valves, including

MOVs, in a consolidated effort (via this

generic letter). Finally, the staff stated

that this generic letter would address

the schedule for completing the

licensees’ response to the pressure

locking and thermal binding issue.

The NRC staff held a public workshop

on February 4, 1994, to discuss pressure

locking and thermal binding of gate

valves, including prioritization of

susceptible valves for corrective action.

A summary of the public workshop is

available in the NRC Public Document

Room and contains information on

evaluation of pressure locking and

thermal binding, and actions taken in

response to the identification of

susceptible valves.

On February 28, 1995, NRC issued

Information Notice (IN) 95–14,

‘‘Susceptibility of Containment Sump

Recirculation Gate Valves to Pressure

Locking.’’ This information notice

alerted licensees to a report from

Northeast Nuclear Energy Company, the

licensee for Millstone Nuclear Power

Station, Unit 2, that both containment

sump recirculation motor-operated gate

valves might experience pressure

locking during a design-basis loss-ofcoolant accident and fail in the closed

position. On March 15, 1995, NRC

issued IN 95–18, ‘‘Potential PressureLocking of Safety-Related PowerOperated Gate Valves.’’ This

information notice alerted licensees to a

report from Connecticut Yankee Atomic

Power Company, the licensee for

Haddam Neck Nuclear Power Plant, that

seven motor-operated gate valves in the

safety injection systems were

susceptible to pressure-locking to the

extent that the operability of the valves

may have been jeopardized.

Discussion

The pressure locking and thermal

binding phenomena are based on wellknown concepts. The identification of

susceptible valves and the

determination of when the phenomena

might occur requires a thorough

knowledge of components, systems, and

plant operations. Pressure locking

occurs in flexible-wedge and doubledisc gate valves when fluid becomes

pressurized within the valve bonnet and

the actuator is not capable of

overcoming the additional thrust

requirements resulting from the

differential pressure created across both

valve discs by the pressurized fluid in

the valve bonnet. For example, the fluid

may enter the valve bonnet (1) during

normal open and close valve cycling, (2)

when a fluid differential pressure across

a disc causes the disc to move slightly

away from the seat, creating a path to

either increase the fluid pressure or fill

the bonnet with fluid, or (3) for a

steamline valve, when differential

pressure exists across the disc and the

valve orientation permits condensate to

collect and enter the bonnet.

Surveillance testing can cause a valve to

experience pressure locking or thermal

binding. For example, an inboard

isolation MOV in the reactor core

isolation cooling (RCIC) system

steamline at a boiling-water reactor

(BWR) plant failed in the closed

position following routine surveillance

testing. Pressure locking and thermal

binding may occur in varying degrees

but may not, in all cases, render a valve

incapable of operating, though a delay

in valve stroke time or valve damage

may occur.

Various plant operating conditions

can introduce pressure locking. Valve

bonnet pressure might be higher than

anticipated, causing pressure locking

under certain conditions. For example,

when (1) 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 (2)

bonnet volume temperature increases,

pressurization results from thermal

expansion of the confined fluid. Valve

bonnet temperature might increase in

response to heatup during plant

operation, ambient air temperature rise

due to leaking components or pipe

breaks, or thermal conduction or

convection through connected piping.

Over time, bonnet pressure could decay

by leakage past the seating surfaces or

stem packing. However, the

depressurization time may be longer

than the system response time to initiate

valve actuation to perform its safety

function. Also, valve actuator operation

at locked rotor conditions for a few

seconds could degrade the motor torque

capability of a motor-operated gate

valve.

Thermal binding is generally

associated with a wedge gate valve that

is closed while the system is hot and

then allowed to cool before attempting

to open the valve. Mechanical

interference occurs because of different

expansion and contraction

characteristics of the valve body and
15802 Federal Register / Vol. 60, No. 58 / Monday, March 27, 1995 / Notices

disc materials. Thus, reopening the

valve might be prevented until the valve

and disc are reheated. Solid-wedge gate

valves are most susceptible to thermal

binding. However, flexible-wedge gate

valves with a high temperature gradient

across the discs may experience thermal

binding.

Pressure locking or thermal binding

occurs as a result of the valve design

characteristics (wedge and valve body

configuration, flexibility, and material

thermal coefficients) when the valve is

subjected to specific pressures and

temperatures during various modes of

plant operation. Operating experience

indicates these situations were not

always considered as part of the design

basis for valves in many plants.

Requested Actions

Within 60 days of the date of this

generic letter, each addressee of this

generic letter is requested to perform

and complete the following actions:

1. Evaluate (in at least a preliminary

manner) the operational configurations

of all safety-related power-operated (i.e.,

motor-operated, air-operated, and

hydraulic-operated) gate valves to

identify those valves that are potentially

susceptible to pressure locking or

thermal binding; and

2. Document a basis for the

operability of the potentially susceptible

valves or, where operability cannot be

supported, take action in accordance

with the Technical Specifications.

Within 180 days of the date of this

generic letter, each addressee of this

generic letter is requested to implement

and complete the guidance provided in

Attachment 1 to perform the following

actions:

1. Evaluate the operational

configurations of safety-related poweroperated (i.e., motor-operated, airoperated, and hydraulic-operated) gate

valves in its plant to identify valves that

are susceptible to pressure locking and

thermal binding;

2. Perform further analyses as

appropriate, and take needed corrective

actions (or justify longer schedules), to

ensure that the susceptible valves

identified in 1 are capable of performing

their intended safety function(s) under

all modes of plant operation, including

test configuration.

Note: If a licensee has already performed

an evaluation of operational configurations to

identify motor-operated gate valves

susceptible to pressure locking and thermal

binding, and has performed additional

analyses and taken needed corrective actions

for identified valves, in a manner that

satisfactorily implements the guidance in

Supplement 6 to GL 89–10 (or equivalent

industry methods) so that the identified

valves are capable of performing their

required safety functions, the licensee need

not perform any additional action under 1

and 2 above for MOVs.

50.54(f) Information Request

1. Requested Information

All addressees, including those who

have already satisfactorily addressed

pressure locking and thermal binding

for MOVs by implementing the

guidance in Supplement 6 to GL 89–10

(or equivalent industry methods), are

requested to provide a summary

description of the following:

a. The susceptibility evaluation of

operational configurations performed in

response to (or consistent with) 180-day

Requested Action 1, and the further

analyses performed in response to (or

consistent with) 180-day Requested

Action 2, including the bases or criteria

for determining that valves are/are not

susceptible to pressure locking or

thermal binding;

b. The results of the susceptibility

evaluation and the further analyses

referred to in (a) above, including a

listing of the susceptible valves

identified;

c. The corrective actions, or other

dispositioning, for the valves identified

as susceptible to pressure locking or

thermal binding, including: (i)

Equipment or procedure modifications

completed and planned (including the

completion schedule for such actions);

and (ii) justification for any

determination that particular safetyrelated power-operated gate valves

susceptible to pressure locking or

thermal binding are acceptable as is.

The staff believes that a corrective

action schedule (if corrective actions are

needed) may be based on risk

significance, including consideration of

common cause failure of multiple

valves. However, the time schedules for

completing corrective action in response

to pressure locking or thermal binding

concerns do not supersede the

requirements of the NRC regulations

and individual plant Technical

Specifications in the event that a safetyrelated valve is determined to be

incapable of performing its safety

function. An addressee’s schedule for

completing corrective action in response

to this generic letter will be considered

independent from GL 89–10.

2. Required Response

All addressees are required to submit

the following written response to this

generic letter:

a. Within 30 days from the date of this

generic letter, a written response

indicating whether or not the addressee

will implement the action(s) requested

above. If the addressee intends to

implement the requested action(s),

provide a schedule for completing

implementation. If an addressee chooses

not to take the requested action(s),

provide a description of any proposed

alternative course of action, the

schedule for completing the alternative

course of action (if applicable), and the

safety basis for determining the

acceptability of the planned alternative

course of action;

b. Within 180 days from the date of

this generic letter, a written response to

the information request specified above

in Requested Information Items 1.a, 1.b,

and 1.c;

All addressees shall submit the

required written responses and report

specified in item 2 above to the U.S.

Nuclear Regulatory Commission, ATTN:

Document Control Desk, Washington,

DC 20555, under oath or affirmation

under the provisions of section 182a,

Atomic Energy Act of 1954, as amended,

and 10 CFR 50.54(f). In addition, a copy

shall be submitted to the appropriate

Regional Administrator.

Backfit Discussion

10 CFR part 50, appendix A, Criteria

1 and 4, and plant licensing safety

analyses, require and/or commit that the

addressees design and test safety-related

components and systems to provide

adequate assurance that those systems

can perform their safety functions.

Other individual criteria in appendix A

to 10 CFR part 50 apply to specific

systems. In accordance with those

regulations and licensing commitments,

and under the additional provisions of

10 CFR part 50, appendix B, Criterion

XVI, licensees are expected to take

actions to ensure that safety-related

power-operated gate valves susceptible

to pressure locking or thermal binding

are capable of performing their required

safety functions. Supplement 6 to GL

89–10 alerted licensees to the problems

with pressure locking and thermal

binding in MOVs, and described an

acceptable approach for addressing

these phenomena for MOVs but did not

request any specific actions or response

form licensees.

The actions requested in this generic

letter are considered compliance

backfits, under the provisions of 10 CFR

50.109 and existing NRC procedures, to

ensure that safety-related poweroperated gate valves that are susceptible

to pressure locking and thermal binding

are capable of performing their intended

safety functions. In accordance with the

provisions of § 50.109 regarding

compliance backfits, a full backfit

analysis was not performed for this

proposed action; but a documented
Federal Register / Vol. 60, No. 58 / Monday, March 27, 1995 / Notices 15803

evaluation was performed, including a

statement of the objectives of and

reasons for the requested actions and

the basis for invoking the compliance

exception. A copy of this evaluation

will be made available in the public

document room.

Attachment 1—Guidance for

Addressing Pressure Locking and

Thermal Binding of Power-Operated

Gate Vales

The following summarizes an

acceptable approach to addressing

pressure locking and thermal binding of

gate valves within the scope of this

generic letter:

1. Perform an evaluation of the safetyrelated power-operated gate valves

having operational configurations that

may be susceptible to pressure locking

or thermal binding. Document the basis

for determining whether valves (a) are

susceptible to pressure locking or

thermal binding or (b) can be removed

from further consideration. For

example, solid wedge disk gate valves

might not be susceptible to pressure

locking. Double disk gate valves are not

likely to be susceptible to thermal

binding.

The evaluation should include

consideration of the potential for gate

valves to undergo pressure locking or

thermal binding during surveillance

testing.

The evaluation also should include

review of generic studies for sitespecific applicability, such as in the

areas of thermal effects and design-basis

depressurization.

Examples of unacceptable reasons for

eliminating valves from consideration of

pressure locking or thermal binding are

(1) leakage rate, (2) engineering

judgement without justification, and (3)

lack of event occurrence at the specific

plant.

Several plants have experienced

either pressure locking or thermal

binding. These cases are discussed in

NUREG–1275, Volume 9. Examples of

gate valves involved in pressure locking

events are:

* Low-pressure coolant injection

(LPCI) and low-pressure core spray

(LPCS) system injection valves;

* Residual heat removal (RHR)

system hot-leg crossover isolation

valves;

* RHR containment sump and

suppression pool suction valves;

* High-pressure coolant injection

(HPCI) steam admission valves;

* RHR heat exchange outlet valves;

* Emergency feedwater isolation

valves; and

* RCIC steamline isolation valve.

Examples of gate valves involved in

thermal binding events are:

* Reactor depressurization system

isolation valves;

* RHR inboard suction isolation

valves;

* HPCI steam admission valves;

* Power-operated relief valve (PORV)

block valves;

* Reactor coolant system letdown

isolation valves;

* RHR suppression pool suction

valves;

* Containment isolation valves

(sample line, letdown exchanger inlet

header);

* Condensate discharge valves; and

* Reactor feedwater pump discharge

valves.

2. Perform a further analysis of the

safety-related power-operated gate

valves identified (in 1 above) as

susceptible to either pressure locking or

thermal binding to ensure all such

valves can be opened to perform their

safety function under all modes of plant

operation, including test configuration.

If a safety-related power-operated gate

valve is found to be susceptible to

pressure locking or thermal binding and

the addressee relies on the capability of

the actuator to overcome pressure

locking or thermal binding,

consideration of the uncertainties

surrounding the prediction of the

required thrust to overcome these

phenomena should be included in the

evaluation. Credit for bonnet pressure

decay within the valve response time

may not be acceptable unless operation

of the actuator under those conditions

will not degrade actuator capability.

Attachment 2 to this generic letter

describes potential resolution options

that may be used by licensees for poweroperated gate valves found susceptible

to pressure locking to thermal binding.

Several preventive and corrective

measures for pressure locking and

thermal binding are also discussed in

NUREG–1275, Volume 9, though each

method has limitations with respect to

applicability, safety, effectiveness, and

cost.

The NRC regulations require an

analysis under 10 CFR 50.59 for any

valve modifications and the

establishment of adequate postmodification and inservice testing of

any valves installed as part of the

modification. For example, addressees

may need to evaluate the effects of

drilling the hole in the disk if this

option is used to resolve a pressure

locking concern. One consideration is

the fact that, with a hole in one disk and

the other disk flexible allowing fluid to

enter the valve bonnet, the valve will be

leaktight with respect to pipe flow in

only one direction.

As required through appendix B to 10

CFR part 50, the addressee may need to

establish training for plant personnel to

perform any necessary actions and

incorporate specific procedural

precautions/revisions into the existing

plant operating procedures. For

example, plant personnel might

periodically stroke certain valves to

reduce the potential for thermal

binding.

Attachment 2—Description of Potential

Resolution Options for Gate Valves

Found Susceptible to Pressure Locking

or Thermal Binding

1. Analysis Only To Justify Adequate

Capability to Overcome the Thrust

Requirements of Pressure Locking or

Thermal Binding

The staff considers the prediction of

the thrust required to overcome pressure

locking or thermal binding to be very

difficult. An addressee may be able to

justify adequate actuator capability in

response to pressure locking for small

valves. The staff does not consider this

alternative appropriate to resolve

concerns regarding thermal binding.

2. Testing Only To Justify Adequate

Capability to Overcome the Thrust

Requirements of Pressure Locking or

Thermal Binding

An addressee may be able to

demonstrate through an in-situ or

prototype test that the actuator has

adequate capability to overcome

pressure locking for a particular valve.

The staff considers this alternative

difficult to justify for thermal binding

concerns because of the uncertainty in

modeling actual plant and valve

conditions.

3. A Combination of Testing and

Analysis To Justify Adequate Capability

to Overcome the Thrust Requirements of

Pressure Locking or Thermal Binding

An addressee may be able to

demonstrate adequate capability of the

actuator to overcome pressure locking

based on test information from the

particular valve or similar valves from

other sources together with an analysis

to demonstrate applicability. As with

Alternative 2, the staff considers this

alternative difficult to justify for thermal

binding concerns.

4. Equipment Modifications To Prevent

Pressure Locking or Thermal Binding

The staff considers this to be the least

difficult alternative to justify and

address pressure locking of susceptible

gate valves.
15804 Federal Register / Vol. 60, No. 58 / Monday, March 27, 1995 / Notices

1 15 U.S.C. 78s(b)(1) (1988).

2 17 CFR § 240.19b-4 (1993).

3See Securities Exchange Act Release No. 35005

(November 23, 1994), 59 FR 61911. The Amex on

November 16, 1994, submitted Amendment No. 1

(‘‘Amendment No. 1’’) to the proposal to allow the

underwriter to link the value of the notes to either

the JPMCI or JPMCIX, depending upon market

conditions and investor interest at the time of the

offering. Additionally, the Amendment provides

that: only options approved accounts will be

permitted to trade the notes; the notes will provide

for a 75% guaranteed return of principal; the index

value will be calculated at least once a day; the

Amex has executed the necessary surveillance

sharing agreements with the relevant commodities

exchanges; and COINs will comply with the CFTC’s

hybrid instrument exemption (58 FR 5580 (Jan. 22,

1993)). See Letter from Benjamin Krause, Amex, to

Michael Walinskas, Derivative Products Regulation,

SEC, dated November 16, 1994.

4The commodities underlying the Indexes and

their approximate weighting are: aluminum (9%),

copper (8%), nickel (2%), zinc (3%), heating oil

(10%), natural gas (7%), unleaded gas (5%), WTI

Light Sweet Crude (33%), gold (15%), silver (5%)

and platinum (3%).

5See Amendment No. 1, supra note 3.

Examples of possible modifications to

prevent pressure locking are provided in

NUREG–1275, Volume 9. Modifications

to prevent thermal binding are also

possible, such as replacing a wedge gate

valve with a parallel-disc gate valve.

5. Procedure Modifications To Prevent

Pressure Locking or Thermal Binding

The staff considers procedure

modification to be a strong alternative

for preventing thermal binding of gate

valves. However, procedure

modifications are less likely to be a

justifiable alternative to prevent

pressure locking of gate valves.

Dated at Rockville, MD, this 20th day of

March, 1995.

For the Nuclear Regulatory Commission.

Brian K. Grimes,

Director, Division of Project Support, Office

of Nuclear Reactor Regulation.

[FR Doc. 95–7431 Filed 3–24–95; 8:45 am]

BILLING CODE 7590–01–M

[Docket No. 50–423]

Northeast Nuclear Energy Co.;

Issuance of Amendment to Facility

Operating License

The U.S. Nuclear Regulatory

Commission (Commission) has issued

Amendment No. 106 to Facility

Operating License No. NPF–49 issued to

Northeast Nuclear Energy Company (the

licensee), which revised the Technical

Specifications (TS) for operation of the

Millstone Nuclear Power Station, Unit

No. 3 located in New London County,

Connecticut. The amendment is

effective as of the date of issuance.

The amendment relaxes the setpoint

tolerance for the pressurizer safety

valves and the main steam safety valves

from ± ±1% to ± ±3%.

The application for the amendment

complies with the standards and

requirements of the Atomic Energy Act

of 1954, as amended (the Act), and the

Commission’s rules and regulations.

The Commission has made appropriate

findings as required by the Act and the

Commission’s rules and regulations in

10 CFR Ch. I, which are set forth in the

license amendment.

Notice of Consideration of Issuance of

Amendment and Opportunity for

Hearing in connection with this action

was published in the Federal Register

on October 12, 1994 (59 FR 51612). No

request for a hearing or petition for

leave to intervene was filed following

this notice.

The Commission has prepared an

Environmental Assessment related to

the action and has determined not to

prepare an environmental impact

statement. Based upon the

environmental assessment, the

Commission has concluded that the

issuance of the amendment will not

have a significant effect on the quality

of the human environment (60 FR

13476).

For further details with respect to the

action see (1) the application for

amendment dated August 4, 1994, (2)

Amendment No. 106 to License No.

NPF-49, (3) the Commission’s related

Safety Evaluation, and (4) the

Commission’s Environmental

Assessment. All of these items are

available for public inspection at the

Commission’s Public Document Room,

the Gelman Building, 2120 L Street

NW., Washington, DC, and at the local

public document room located at the

Learning Resource Center, Three Rivers

Community-Technical College, Thames

Valley Campus, 574 New London

Turnpike, Norwich, CT 06360.

Dated at Rockville, Md., this 17th day of

March 1995.

For the Nuclear Regulatory Commission.

Vernon L. Rooney, SR.,

Project Manager, Project Directorate I–4,

Division of Reactor Projects–I/II, Office of

Nuclear Reactor Regulation.

[FR Doc. 95–7432 Filed 3–24–95; 8:45 am]

BILLING CODE 7590–01–M

SECURITIES AND EXCHANGE

COMMISSION

[Release No. 34–35518; File No. SR–AMEX–

94–30]

Self-Regulatory Organizations;

American Stock Exchange, Inc.; Order

Approving Proposed Rule Change

Relating to the Listing and Trading of

Commodity Linked Notes

March 21, 1995.

I. Introduction

On August 22, 1994, the American

Stock Exchange, Inc. (‘‘Amex’’ or

‘‘Exchange’’) submitted to the Securities

and Exchange Commission (‘‘SEC’’ or

‘‘Commission’’), pursuant to Section

19(b) of the Securities Exchange Act of

1934 (‘‘Act’’),1 and Rule 19b-4

thereunder,2 a proposed rule change to

list and trade Commodity Linked Notes

(‘‘COINs’’), intermediate term notes

whose value will be linked in part to

changes in the levels of either the J.P.

Morgan Commodity Excess Return

Index (‘‘JPMCIX’’) or the J.P. Morgan

Commodity Return Index (‘‘JPMCI’’

together with JPMCIX, ‘‘Indexes’’).

Notice of the proposed rule change

and Amendment No. 1 (defined herein)

was published for comment and

appeared in the Federal Register on

December 2, 1994.3 No comments were

received on the proposal. This order

approves the proposal, as amended.

II. Description of Proposal

The Amex proposes to list for trading

under Section 107 of the Amex

Company Guide (‘‘Section 107’’) a new

hybrid product called COINS. COINs are

intermediate term notes whose value

will be linked in part to changes in the

level of a commodity index consisting of

base metals, precious metals and energy

related commodities. More specifically,

the value of COINs are based on an

index that replicates a trading strategy

whereby an investor holds a futures

position in each of eleven exchangetraded commodities for a one-month

period and then rebalances the positions

of the commodities held for the

following month to maintain a constant

dollar weighting scheme.

A. Description of the Indexes

COINs will be linked to either the

JPMCI or the JPMCIX, both of which

measure the return from an investment

in the same eleven industrial futures

contracts.4 According to the Exchange,

the JPMCI and JPMCIX are identical in

all aspects except for the incorporation

of ‘‘collateral return,’’ as more fully

described below, into the JPMCI.5 Both

Indexes are designed to replicate a

trading strategy, described more fully

below, that holds a futures position in

each of the eleven futures for a one

month period and then rebalances the

volume of commodities held for the

following month based upon a constant