ML20033C676

Forwards Guidelines for Demonstraton of Operability of Deep Draft Pumps.Requests Schedule Indicating Response That Discusses Util Assurance Program & Extent of Conformance W/Guidelines

ML20033C676
Person / Time
Site:	River Bend
Issue date:	11/16/1981
From:	Tedesco R Office of Nuclear Reactor Regulation
To:	William Cahill GULF STATES UTILITIES CO.
References
REF-SSINS-6820 IEB-79-15, NUDOCS 8112030634
Download: ML20033C676 (18)

Text

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NOV 16 1981 Docket Ifos.:'46aLS8 and 50-459 EV GY Y( Jl'\\f }h

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fir. Willian J. Cahill, Jr.

Senior Vice President NOVI 8 igg;w p

f3-v.s.uxua nouren O' '

River Bend ?!uclear Group Gulf States littlities Cocpany

' h' Post Office Box 2951

' N, 7

Beaumont, Texas 77704 U1

Dear fir. Cahill:

Subj ect: Long Tem Operability of Deep Draft punps IE Bulletin 79-15, dated July 11, 1979, was issued to all licensees and holders of construction pemits as a result of deep draft pump deficiencies

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that were identified at facilities both operating and under construction.

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For per, ding OL applications, long tem operability of dei'p draft purps is now being reviewed by the staff during the nomal licensing review process.

In order to facilitate this review, enclosed is a document entitled,

" Guidelines for Demonstration of Operchility of Deep Draf t Punps". Within

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30 days from the issuance date of this letter,(you should provide a schedule indicating when a response, in the fom of ? supplement to FSAR Section 3.9.3, would be provided that discusses your assurance progr6n for demonstrating long tem operability of your deep draft puaps and the extent to which it confoms to the various portions of these Guidelines.) Enpbasis should be placed on (1) the establishnent of installation procedures that are followed each time these punps are disassembled and reinstalled, and (2) the testing requirenents cnd bearing wear criteria. The instrumentation called for in the Guidelines should not he considered a requirement.

These Guidelines establish an acceptable nethod of assuring long tem operability of deep draft pumps. They do not necessarily constitute the only method for demnstrating long tem operability. The staff will review the information you submit to detemine whether your long tem operability assurance proqran for deep draft pumps is in sufficient confomance with these Guidelines to assure long tem operability.

If not, the staff will datomine whether you have established and utilized other nethods and 3

procedures, preferably with the assistance of the puns nanufacturer, that also demonstrate and assure that these punns will perfom their intended fu ctions for the length of tine required.

OFFKE) 8112030634 01111 smaus )

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pare) c ronu.us oo macu cao OFFICIAL RECORD COPY usa

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< If you have any questions regarding this matter, please contact Robert Perch -

Licensing Project Manager for River Bend, on (301) 492-8135.

The application / reporting requirements contained in this letter have been-approved by the Office of fianagement and Budget; OMB Approval No. 3150-0011.

Sincerely.

Original signed by g). TodoS" Robert L. Tedesco, Assistant Director for Licensing Division of Licensing Office of Huclear Reactor Regulation

Enclosure:

Guidelines for Demonstration of Operability of Deep Draft Pueps i

cc w/ enclosure:

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See next page -

DISTRIBUTION:

Docket File LB#2 File Attorney, OELD DEisenhut/RPurple RTedesco ASchwencer MService ILE.(3).

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" Mr. !!illiam J. Cahill, Jr.

Senior Vice President River Bend Nuclear Group Gulf States Utilities Company Post Office Box 2951 Beaumont, Texas 77704 cc:

Troy B. Conner, Jr., Esquire Conner and Wetterhahn 1747-Pennsylvania Avenue, N. W.

. Washington, D. C. 20006 Mr. J. E. Booker Manager -Technical Programs Gulf States Utilities Conpany Post Office Box 2951 i

Beaumont, Texas 77704 Stanley Plettman, Esquire Orgain, Bell and Tucker Beaumont Savings Building Beaumont, Texas 77701 Karin P. Sheldon, Esquire Sheldon, Harmon & Weiss 1725 I Street, N. W.

Washington, D. C. 20006 William J. Guste, Jr., Esquire Attorney General State of Louisiana Post Office Box 44005 State. Capitol Baton Rouge, Louisiana 70804 Richard M. Troy, Jr., Esquire Assistant Attorney General in Charge State of Louisiana Department of Justice 234 Loyola Avenue New Orleans, Louisiana 70112 m

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ENCLOSURE GUIDELINES FOR DEMONSTRATION OF OPERASILITY OF DEEP DRAFT PUMPS DISCUSSION

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I.E.Bulletin 79-15 dated July 1979, identified problems associated with deep-draf t' pumps found at operating f acilities and near tenn operating licensee facilities.

Deep draf t pumps,dich are also '

.called

• vertical turbine p, Umps are usually 30 to 60 feet in length with i=pellers 7tcated in casing bewis at the lowest elevation of.-.

the pu=p.

The motor (driver) is 1ccated at the highest pu=p elevation with the discharge nozzle just below the motor.

Bulletin 79-15 was initiated because several nuclear power plant facilities could not demonstrate operability of their pumps. The pu=ps were experiencing. excessive vibration and bearing ' wear. The~

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ra id bearing wear suggested that these pumps could not perfor:a r

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their re:;utred functions during or following an accident. As a result of the staff's initial review of the responses to IE3 79-15,.

several plants were identif'ied as having potential problems with their' deep.draf t pumps. These guidelines are provided fer these '

plants'so that the licensee or applicant involved may have a method acceptable to the staff.for demonstrating the operability of deep-draft pumps.

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DEEP DRAFT PUMP OPERATING CHARACTERISTICS In order to better understand the operating characteristics of

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1 these pu:ps, a rotor dynaraics analyses was performed to ascertain the response of the pump rotor under stea# state cperation.

The analyses considered journal bearing to shaft @namic respense at various eccentricities and fluid viscosities. The raadel for the analysis depicted a typic 61 deep draft pucp utilized by the

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' nuclear industry.

The analysis resulted in rec,cr:rendation,s for irgroving the stability of the pump retor from externally appl.ied inputs and by self-generated inputs.

The conclusions which were derived frem the analysis ani! staff evaluations of Nerth Anna, Beaver Valley and Surry facilities with similar purps ine'4ude:

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1.)

pumps with this type of configuration are prone to baaring whirl vibration prcblems due to the flexibility cf the rotor and casing structure.

This phencrenen is accentuated as jcurnal bearing clearance beceres large. This phencrenen leads to bearing wear (Jeurnal bearings).

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" Low Head Safety Injection Pucp Retor Dynamic Analyses", by Franklin Research Center, Report FC4952, dated May 1980.

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m 2.) There may be natural frequencies associated with the pump assembly which occur near the operating speed of the pump.

P'$mp operation will drive these frequencies and can cause bearing wear. The severity of this conditten is dependent on bearing diametral clearance, rotor unbalance conditions and housing flexibility. As an example, if the wear in column journal bearings becomes sufficiently large

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(twice the original diametral cl earance)'so that these bearings are no longer active and the undamped critical frequency near the ope, rating speed of the pump is allowed to expand, the additional uncontrolled bearing 4

wear will eccur..This wear can centinue until the shaf t

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rubs against the support struc,ture of the bearing and can potentully sever the shaf t.

3.)

One acceptable method for correcting instabilities in the

, pump shaf t is to utilize a j:urnal bearing design which exhibits stable characteristics.

One such design is the

• Taper land bearing". This design is more stable than the plain journal bearing, is less susceptible to wear because of the taper and vt11'cause the bearing to forn a hydro-dynamic film quickly during startup.

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4.). Stiffening -of the colu=n sections of the pump is

, advantageous if there is a coiumn fr quency near the operating speed of the pump.

The shifting of the column frequency' to a higher level will eitminate any coupling between the pump. operating speed and the

.' coluen frequency.

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5.) Flow inlet conditions to the pumps and s p designs can be important to pump operabflity.~~ Certain installations.

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have demonstrated flow character,istics which produced vortexing at the bellmouth of the pump.

This vortexing

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is due to sump design or sump supply line entrance con-

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ditions. This condition can contribute to additional pump vibration and we.ar. Flev straightener devices, reducticn of be11m:uth diameters, and bottom clearance reductions have proven to be effective in eliminating this problem.

6.) This type of pump has exhibited operational problemi due to design and installation deficiencies. The high flexibility of the shaft and column make this design rather forgiving when-it comes to insta11atten deficien-cies such as misalignment between be shaft and column, 4 -

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.5 1ow-precision coupling asse=blies, and non-perpendicular

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v.ounting n anges. This fact however, can lead to excessive.

bearing wear without significant noticeable change in pu=p operating characteristics. To ensure proper pu=p operation, proper alignment should be established between all c.atin~g surfaces and measures should be emphasized which pre /ent column-These measur's can include optical-and shaf t eccentricities.

e aligr. ment of the column segments, use of high precision couplings and use of accurate techniques to establish that the su=p plumb line is-perpendicular to the pu=p mounting fl ange.

The above findings and conclusions have contributed significantly to the devel:peent of these guidelines.- The guidelines listed below are divided _into = installation and test areas.

The subjects to be addressed in these areas are considered to be cf prime importance when establishing a peep cperability assurance prograh.

The extent to which esch of the two are'as are implemented at a specific facility is dependent on specif1c sy=ptoms which have been identified with these. pumps while 'in operatten and during service periods.

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Implementing the measures outlined below, at North Anna 1 A' 2 in total, has been shown to provide reasonab'le assurance that the pumps.

will be operableyhen required for their safety function. These

'~ guidelines are' not intended to replace the requirements of

• Standard Review Plan 3.3.3, Regulatory Guide 1.58 or any other

' requirements presently enforced' by the staff.

Rather, the

~ guidelines are to be used as supplementary material for establishing deep-draf t pump operability.

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GUIDELINES FOR OPERASILITY INSTALLATION 1.0 INSTALLATION PROCEDURES Experience has shown that these pumps

• are prone to having operability problems as a result of poor installation procedures.

The guidelines emphasize those areas of the installation procedure, which if impi ented,'

f could significantly improve the likelihood of an operable pump. The procedures utilized shculd' be submitted to the staff for review.

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1.1 PUW INSTALLATION 4

Determine by measurement that all shaft segrants a're straight a.

within tolerances specified by the manufactur'er.

b.

Detemine by measurement or provide certification that all couplings (for shaft segments & ' pump to motor coupling) are of high precision as specified by the manufacturer.

- l Detemine by measurement that all pump segment flanges are c.

perpendicular to the centerline of the se; ment, that the

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segments are straight and that' any mating surfaces are concentric to an established dat::m. *dere journal ~ "

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centricity between this assedly and its rating surface.

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d.

Align full pump casing assedly optically to assure raxicum straightness and concentricity of the assedly.

Any equivalent rethod is acceptable, as long as the

-procedure stresse' column straightness and concentricity.- :

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Assure pug 'to motor flange perpendicularity and that e.

preper coupling installation is perf orced.

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Assure that all nating surface bolting is properly attached and that ranuf acturer terquing sequences are adhered to.

1.2 SU".P INSTALLATION a.

Assure (where used) that sump / pup mating flange is perpendicular to the sump pump line.

a b.

Assure that sump design prevents fluid ancralies such as vortexing or turbulence r. ear the Stah

c the pump tellecuth and that in:: ming,. ping is not so designed as to alicw fluid concitiens f avorable to these ancmalies (i. e., sha. p.'

bends in piping prior to entrance. into sunp).

c.

Assure that interference does 'nct exist between the surp and ary pump appendage such as a seismic restraint.

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'2.piTestingRec.uirements p

Th$1nstalldion procedures are essential in establishing purp -

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p-.Joperabil ty.

3n addition to careful installation, testing my p,

be requ', red whl'ch will verify proper operation of these. pumps.

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, Af ter orpl'eti l of the installation checks, licensees or appli-c

' 4 w\\' cahts shebid evaluate the need for further testing and rep ort

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y' the.results 'of this evaluation ^ together with the details of any M%o tesppia to the' staff.

Should tests be required, an acceptable

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g ' test yrccedure should include the items listed bslow.

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The. staff recoenizes'that the instrumentation and procedures outlined below L

may be difficult to implerent at all facilities and, therefore, the

, staff is erphasizing good installation p'ractices which lead to G

d, t oper:bie ek,:penents.

If tests demonstrating operability cannot

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E-br$orpass all the items listed below, then alternative procedures should be prcposed f or evaluation' by the staff.

The tests should e:phasize reasurement of pu p dynamic characteristics and wear data at dif ferent stages of testing, culminating with an er.rapelation of the da.a to the desired life scal for the pu:p.

2.1 Test Instrumentation The follocing instrumentation should be incorporated into the test procedure aside from nor:al flow measu'cerent, pressure and vibration instrumentatien:

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a.-)

X, Y' proxicity probes at three-axial locations on the pump column, for measuring and recording radial positions of shaf t with respect to the column.

b.)' X, Y, accelerometers (at proximity prebe locations)

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for measuring and recording radial accelerations of the coiumn.

c.) Dynamic pressure transducers for reasuring fluid pressure

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at the following locations :

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1.

Bottom of Column (suction)

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2.

Mid-Celumn 3.

Top of Colu=n.

d.) Shaf t Rotational speed and dynaaic variation instrument.

2.2 PPeE-TEST DATA With the pump disassembled, measure a11 journal bearing 0.D.'s, bea,-ing 1.D.'s and calculate bearing diametral clearances.

Ir3 addition with pumps fully assembled and using the proximity probes,

obtain the " clearance circle" at each of the three axial stations by rolling.the shaf t section within the clearance volume of'its bearings and in this way, establish proper operation of the p, robes.

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3.1 PliASE 1 Testing (6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> plus start-stop)

This' phase of testing should be comprised of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> of testing-(Sreat-in) followed by start-stop testing. Test conditions should simulate as nearly as,,pos,s,1ble nomal and accident conditions._ Parameters to be considered

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are flow, temperature, debris, and chemical composition

' of fluid being pumped.

Static torque tests should be *

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performed before and after the test (i.e. measure amount of torque' required to turn shaft by hand). Data should be.

taken during the ~six hour test, at 1/2 hour intervals.-

'A,tetal of 12 start-stop tests. will be perfomed con-

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sisting of a start up frem aero speed up to full-speed, 10-minute dwell at full-speed and a shutdown from full speed to ero speed, with recording of all instrumentation i

during full cycle of start-stop.

Upon completion of Phase 1 testing,the following data should be cbtained and recorded:

1.) Obtain the 't.learance circles" using theihree sets of proximity probes. -

1 2 Tests at North Anna 1- & 2 and Manufacturers ir.put indicates that 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> is an adequate time interval for bearing "breat in" period...

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• 2. ) P.easure and record the following dimension: for each bearing:

a. )_ Journal 0.D.

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b.) Bearing I;D.

c.) Eearing to Journal diametral-clearance d.) Establish Phase 1 test bearing wear.

THE" ACCEPTANCE CRITERIA IS AS FOLLOW 5:

1.)

If wear is? 5 mils for any bearingIwear is unaccepnble,

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and test shculd be terminated.

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If wear is( 5 mils for all bearings

a. ) Reassemble the punp

b. ) Obtain " clearance " circles"

c. ) Reinstall pump in test loop. '-

2.4 Phase 2 Testing (48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />)

Phase 2 testing is to be perferred at full syste= pressure.

and terperature and fluid ccaditions siculating.those expected durir.g accident and acrmal operation.

Before start and at c'ocpletien of Phase 2 test,obtain reasurerent of static torque.

Data should be recorded contir.'cusly during the start-up period, p

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and during the shutdown period. Data should also be reco'rded ~

at 1-h'our time -intervals during the 48 hcur test.,,

The following' me~asureren'ts. should.be rm:de at the cocpl.etion. -

of Phase 2 of the testi

1. ) Obtain the "cle'arance circles *_ us ing the thi ee.s.e.ts.;of.:

proximity. probes.

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_g 2.) P,tasure and r.ecord i.he~ following dicensiens for 'each bearing:.

'a.-) - J ou rna l O'.D.

b. ). S ea r.i ng I.D..

c. ) Bearin~g to Jcurnal diametral cleerance.

d.) Establish accuculated bearing wear.

THE ACCEPTANCE CRITERIA IS AS FOLLOW 5:

1.)

If accurulated bearing wear on any bearing is

>7 mils, wear is unacceptable and test shculd be t erni nat ed.

2.)

If accu::ulated wear en all bearings ist.'7 mils forallbearings$.

.f a.)

Reassemble ~ pump

b. )

Obtain " clearance circles" -

c.)

Reinstall pump in test icep.

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5.). Phash 3 Testing (95 hours0.0011 days <br />0.0264 hours <br />1.570767e-4 weeks <br />3.61475e-5 months <br />)

Phase 3 testing is to be perfomed at full system pressure and temperature and Lflu'd conditions simulating those expected '^

s during accident and normal operat' ion. The sa.-c peccadures

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should be folicwed as in Phase 2 +esting except that data may be taken with Iess frequency.

The same maasurements should be taken at the ccmpletion of this phase as with the other phases with the following acceptance criteria:

1.)

If accumulated bearing wea- <s) 8 mils for.any bearing 3 wear is unacceptable and test should be teminated.

2.)

If accue.ulated wear is ( B mils for all bearings,3,

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decision needs to be made to establish:

a.)

the need for additional testing or

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b.)

whether or not the bearing wear will be accephably low.

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The recc=6 ended decision process is outlined belew.

P,1ot the values of accumulated wear versus time (H) for each

- b, earing after Phase 2 and Phase 3 tests, namely, Wear ~ at H2 = 54 hour6.25e-4 days <br />0.015 hours <br />8.928571e-5 weeks <br />2.0547e-5 months <br />

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Vear at H3 = 150 hours0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br /> 6

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Straight lines are then drawn through the plotted vali.es of wear and extended to the right (See example Figure 1).

If the extension intercepts the maximum acceptable value of wear (8 mils) at a Yalue

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If the intercept of the line with wear of 8 mils exceeds the.11fe goal for this pump, no additionil testing is '

required and bearing wear is acceptable., If addition.a1 testing,-

is deemed necessar'y it should be done in a similar manner to that

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perfor:ed during Phase 3 with similar accertance criteria and decision process.

It is expected that such additional tetting will either show a stable pump operation with no increase in bearing wear or increased bearing we~ar with unacceptable results.

2.6 Evaluation of Puco Acceptability

.If bearing wear (af ter all testing phases) is acceptably low (as per decision process) and if vibration levels oyer the frequency spectrum of 3 cps to 5000 cps are acceptably low and show no unfavorable trend of increasing magnitude during the testing,- the pump may be. judged acceptable for ite intended use.

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