ML17276B618

Forwards Request for Addl Info Re Purge & Vent Valve Operability Qualification

ML17276B618
Person / Time
Site:	Columbia
Issue date:	09/16/1982
From:	Schwencer A Office of Nuclear Reactor Regulation
To:	Ferguson R WASHINGTON PUBLIC POWER SUPPLY SYSTEM
References
NUDOCS 8209280493
Download: ML17276B618 (12)

Text

S~P 16

>gee mDocket No.:

50-397

'r.

R. L. Ferguson Hanaging Director Washington Public Power Supply System P.

O. Box 968 3000.George Washington

'Way Richland, Washington, 99352

Subject:

Request for Additional Information

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NRC PDR LB82 File Local PDR RAuluck NSIC EHylton PRC I&E

Paton, OELD ACRS (16)

Region V

HHaughey On February 17, 1982, an informal copy of the WPPSS Nuclear Power Project 2

(WNP-2) qualification analysis for the containment purge and vent valves was given to H. Haughey of the Equipment gualification Branch (E(B) for 'staff comments.

During the month of February, 1982, staff comments on the qualification ~'do'c'u'ments were verbally given to Supply System.

Additional qual,'ilfication work required, particular,'ly in the area of dyna'mic flow loads, was identified in those discussions.

Since that

time, no additional qualffication reports have been submitted to the staff.

'Enclosure 1 contains specific ~comments to the informal submittal of February 17, 1982.

The qualification package as received February 17, 1982, does not represent a complete and acceptable qualification package for these valves under the combined DBA-LOCA plus SSE loads.

Enclosure 2 is a standard request form for information for purge and vent valve operabil ity qual'ification.

The Supply System should formally submit the qual;ification documents in accordande with Enclosure l.

In addition, the questions in Attachment 1 to Enclosure 2 should also be responded to.

To maintain our licensing review s,chedule for <the WNP-2

FSAR, we will need responses to the enclosed request by October 15, 1982, If you cannot meet this date, please inform us within seven days after receipt of this letter of the date you plan to submit your responses'Co that we may rev.iew-our s,chedule for any necessary changes.

Please cori,tact Raj Auluck, Licensing Project Hanager, if your desire any discussion or c1irification of the enclosed request.

Sincerely, aa09ae0493 8209l6 PDR ADOCK 05000397 A

PDR A.

chwencer, Chief Lic'ensing Branch No.

2 OFFICE/

SURNAME/

Encl'res

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WNP-2 Mr. R. L. Ferguson Managing Director

-Washington Public Power Supply System P.

0.

Box 968 3000 George Washington Way

Richland, Washington 99352 CC:

Nicholas Reynolds, Esquire Debevoise 8 Liberman 1200 Seventeenth

Street, N.

W.

Washington, D. C.

20036 Mr. G.E.

Ooupe, Esquire Washington Public Power Supply System P.O.

Box 968 3000 George Washington Way

Richland, Washington 99352 Nicholas Lewis, Chairman Energy Facility Site Evaluation Council Mail Stop PY-ll Olympia, Washington 98504 Roger Nelson, Licensing Manager Washington Public Power Supply System P.O.

Box 968

Richland, Washington 99352 Mr. W.G. Conn, Sr.

N/M Group Supervisor Burns and Roe, Incorporated 601 Williams Boulevard Richl and, Washington 99352 Mr. Richard Feil U.S.

NRC Resident Inspector WPPSS-2 NPS P.O.

Box 69 Richl and, Washington 99352 Dr. G.D. Bouchey Deputy Director, Safety 5 Security Washington Public Power Supply System P.O.

Box 968, MD 650

Richland, Washington 99352

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ENCLOSURE 1

Comments to WNP-2 Purge and Vent Valve gualification Documents 4

The torque sizing letter of January 9, 1976, BlF to Burns and

Roe, indicated the dynamic flow forces of air during normal operation were negligible and the seating torque was considered the governing design load.

Dynamic loads under LOCA pressures were not considered.

MPPSSshould determine if the dynamic flow loads during OBA-LOCA pressures are negligible as compared to the seating torques.

The dynamic flow loads must be. based on test (either model or actual size).

2.

3;

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4.

,5.

The applicant should show the operator has the ability to close the valve at all angles.

Dynamic torque loads will vary with disc angle.

The April 17, 1976 letter B1F to Burns and Roe indicated operator torque capability also. varies with disc angl e.

If the dynamic torque under LOCA pressure for these valves is greater than the seating torque, a new analysis should be performed to show the effects of combined LOCA dynamic loads plus SSE seismic loads.

Stress al 1 owabl es for the analysis are yield strength values.

No additional margin is applied.

Stress allowables'hould reflect some margin.

For example:

the maximum shear allowable should be.6 Sm (Sm as defined by ASME B8PV code,Section III) for ASME Section III Components or.4 Sy (Sy = yield strength,.

allowable as defined by AISC) for all other components.

In

~ addition, ultimate strength was used for non-pressure boundary components.

For valves required to operate conservative allowables should be used to allow for deviations in manu-facturing.

Margins should be conservatively applied.

The valve appears to have natural frequencies at 17.3 Hz and 23.9 Hz but the seismic analysis for the valve assembly assumed the valve.to -be rigid.

In addition, seismic quali-fication for a component which has a function beyond simple pressure boundary should be qualified by test.

ENCLOSURE 2

Operability Qualification of Purge and Vent Valves'72.01 Demonstration of operab'ility of the containment purge and vent valves and the ability of these valves to close during a design basis accident is necessary to assure containment isolation.

This demonstration of operability is required by NUREG-0737, "Clarification of TMI Action Plan Requirements," II.E.4.2 for containment purge and vent valves which are not sealed closed during operational conditions 1, 2, 3 and 4,

1.

For each purge and vent valve covered in the scope of this review, the following documentation demonstrating compliance with the "Guidelines for Demonstration of Operability of Purge and Vent Valves" (Attachment 2) is to be submitted for staff review:

A.

Dynamic Torque Coefficient Test Reports (Butterfly valves only) - including a description of the test setup.

B.

Operability, Demonstration or In-situ Test Reports (when used)

C.

Stress Reports D.

Seismic Reports for Valve (valve and operator) and E.

Sketch or description of the following (Butterfly Assembly associated parts.

each valve insta'Elation showing valves only):

1.

2.

3-4.

5; direction of flow disc closure direction curved side of disc, upstream or downstream (asymmetric discs) orientation and distance of elbows, tees,

bends, etc. within 20 pipe diameters of valve shaft orientation distance between valves F.

Demonstration that the maximum combined torque developed by the 'valve is below the actuator rating.

2.

The applicant should respond to the "Specific Valve Type Questions" (Attachment

1) which relate to his valve.

'3.

Analysis, if used,

'should be supported by tests which estab-.

blish torque coefficients of the valve at various angles.

As torque coefficients in butterfly valves are dependent on disc

shape, aspect ratio, angle of closure.flow direction and approach flow, these. things shoul'd be accurately represented during tests.

Specifically, piping 'installations (upstream and downstream of the valve) during, the test should be representative of actual=-field

=

installations.

For example, non-symmetric approach flow from an elbow upstream of a valve can result in fluid dynamic torques of double the magnitude of those found for a valve with straight piping upstream and downstream.

4.

In-situ tests, when performed on a representative

valve, should be performed on a valve of each size/type which is determined to

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represent the worst case load.

Worst case flow direction, for

example, should be considered.

5.

For two valves in series where the second valve is a butterfly valve, the effect of non-symmetric flow from the first valve should be considered if the valves are within 15 pipe diameters of each other.

6. If the applicant takes credit for closure time vs. the buildup of containment pressure, he must demonstrate that the method is conservative with respect to the actual valve closure'ate.

Actual valve closure rate is to be determined under both loaded

%nd'nloaded conditions (if valves close faster at. all angles-.of opening under loaded conditions, no load closure time may be used as conservative) and periodic inspection under tech.

spec.

require-

'ments should be performed to assure closure rate does not increase with time or use.

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Specific Valve Type Questions g7p-Op

~ The following questions apply to specific valve types only and need to be answered only where applicable.'f not applicable, state so.

A.

Torque Due to Containment Backpressure Effect (TCB)

For those air operated valves located inside containment, is the operator design of a,type that can be affected by the containment pressure rise (backpressure effect) i.e.,

where the containment pressure acts to reduce the operator torque capability due to TCB.

Discuss the operator design with respect to the air vent and bleeds.

Show how TCB was calculated (if applicable).

B.

Where air operated valve 'assemblies use accumulators as the, fail safe feature, describe the accumulator air system configuration and its operation.

Discuss active electrical component's in"the accumulator

system, and the basis used to determine their quali-fication for the environmental conditions experienced.

Is this system seismically designed?

How is the allowable leakage from the accumulators determined and monitored?

C.

For valve assemblies requiring a seal pressurization system (inflatable main seal),

describe the air pressurization system configuration and operation including means, used to determine their qualification for the environmental condition experienced.

Is this system seismically'designed?

D.

Where electric motor operators are used to close the valve has the minimum available voltage to the electric operator under both normal or emergency modes been determined and specified to the operator manufacturer to assure the adequacy of the operator to stroke the valve at accident conditions with these lower limit voltag'es available?

Does this reduce voltage operation result in any significant change in stroke timing?

Describe the emergency mode power source used.

E.

Where electric motor and air operator units are equipped with handwheels, does their design provide for automatic re-engagement of the motor operator following the handwheel mode of operation?

If not, what steps are taken to 'preclude the possibility of th'e valve being left in the handwheel mode following some maintenance, test etc.

type operation2 For electric motor operated valves have the torques developed during operation been found to be less than the torque limiting settings2.

ATTACHMENT..l. TO ENCLOSURE 2

Guidelines for Demonstration Of Operability of Purge and Vent Valves erabilit In order to establish operability it must be shown that the valve actuator's torque capability has sufficient margin to ove'rcome or resist the torques and/or forces (i.e., fluid.dynamic, bearing, seating, friction) that resist closure when stroking from the initial open position to full seated (bubble tight) in the time limit specified.

This should be predicted on the pressure(s) established in the containment following a design basis IQCA.

Considerations which should be addressed in assuring valve design adequacy include:

.I.

Valve closure rate versus time " i.e., constant rate or other.

L 2.

Flow direction through valve; QP'across valve.

3.

Single valve closure (inside containment or outside containment valve) or simultaneous closure.

Establish worst case.

4.

Containment back pressure effect on closing torque margins of air operated valve which vent pilot air inside containment.

5.

Adequacy of accumulator (when used) sizing and initial charge for valve closure requirements.

6.

For valve operators using torque limiting devices - are the settings of the devices compatible with the torques required to operate the valve during the design basis condition.

7.

The effect of the piping system (turns, branches) upstream and downstream of all valve installations.

8.

The effect of butterfly valve disc and shaft orientation to the fluid mixture egressing from the containment.

'emonstration Demonstration of the various aspects of operability of purge and vent valves may be by analysis, bench testing, in-situ testing or a combination of these means.

Purge and vent valve structural elements (valve/actuator assembly) must be evaluated to have sufficient stress margins to withstand loads imposed while valve closes during a design basis accident.

Torsional shear,

shear, bending, tension and. compression loads/

stresses should be considered.

Seismic loading should be addressed.

Once valve closure and structural integrity are assured by analysis, testing or a suitable combination, a determination of the sealing integrity after closure and long term exposure to the containment environment should be evaluated.

Emphasis should be directed at the effect of radiation and of the containment spray chemical solutions on seal material.

Other aspects such as the effect on sealing from outside ambient temperatures and debris should be considered.

The following considerations apply when testing is chosen as a means for demonstrating valve operability:

Bench T~eecin A.

Bench testing can be used to demonstrate suitability of the in-service valve by reason of its traceabiljty in design to a

test valve.

The following factors should be considered when qualifying valves through bench testing.

1.

Whether a valve was qualified by testing of an identical valve assembly or by extrapolation of data from a similarly designed valve.

2.

Whether measures were taken to assure that piping upstream and downstream and valve orientation are simulated.

3.

Whether the following load and environmental factors were considered a.

Simulation of LOCA b.

Seismic loading c..

Temperature soak d.

Radiation exposure e.

Chemical exposure Debris B.

Bench testing of installed valves to demonstrate th suitability of the specific valve to perform its required function during the postulated design basis accident is acceptable.

1.

The factors listed in Items A.2.and A.3 should be considered when taking this approach.

In-Situ T~eetin In-situ testing of purge and vent valves may be performed to confirm the suitability of the valve under actual conditions.

When performing such tests, the conditions (loading, environment) to which the valve(s) will be subjected during the test should simulate the design basis accident.

NOTE:

Post test valve examination should be performed to establish structural integrity of the key. valve/

actuator components.