ML20011B218

Forwards Guidelines for Demonstration of Deep Draft Pump Operability for Response within 30 Days as Suppl to FSAR Section 3.9.3.Long-term Operability Is Being Reviewed Per IE Bulletin 79-15

ML20011B218
Person / Time
Site:	Byron
Issue date:	11/18/1981
From:	Tedesco R Office of Nuclear Reactor Regulation
To:	Delgeorge L COMMONWEALTH EDISON CO.
References
IEB-79-15, NUDOCS 8112040634
Download: ML20011B218 (18)

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Docket Hos.: STH 50 454 MRushbrook TIC and STN 50 455 WKane ACRS (16)

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N Mr. Louis 0. DelGeorge RVollmer 3

Director of Huclear Licensin9 TMurley Jb

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Post Office Box 767 RHartfield, MPA i.

NOV2 01931>

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Dear Mr. De1 George:

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Subject:

Long Tem Operability of Deep Draft Pumps.

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IE Bulletin 79-15, dated July 11, 1979,' wii isf ued -t, all licensees and

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holders of construction permits as a resuP. ofideep draft punp deficiencies I

that were identified at facilities both ' operating and under construction.

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For pending OL applications, long term operability of deep draft pumps is now being reviewed by the staff during thynormal licensing review process.

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

" Guidelines for Demonstration of Operability of Depp Draft Punps". Within 4

j 30 days from the issuance date of this letterf you should provide a schedule 1

indicating when a response, in the fom of a supplement to FSAP, Section 3.9.3, NJ would be provided that discusses your assurance progran.fo'r denonstrating l

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long tem operability of your deep draft puinps and the extent. to which it i

confoms to the various portions of these Guidelines. Emphasis 3hould be placed on (1) the establishment of installation proceduces that are followed

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each time these pumps are disassembled and reinstallithdnd (2) the testing

-s requirer,ents and bearing wear criteria. The instreacntatipa called for irt N

the Guidelines should not be considered a requiremnt.c n _

s-These Guidelines establish an acceptable method of assu(ing long tem operability of deep draft pumps. They do not necessarily constitute the-only mothed for demonstrating long tem operability. The staff will review the infomation you subnit to detemine whether your long tem operability l

assurance progran for deep draft pumps is in sufficient confomance with these Guidelines to assure long tem operability.

If not, the staf f will detemine whether you have established and utilized other methods and -

procedures, preferably with the assistance of the putnp nanufacturer, that.

i also denonstrate and assure that these pumps will perfom their intended functions for the length of tine required.

-e 0112040634 81111 PDR ADOCK 050004 A

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oan p nac ronu m oo-m ancu ano OFFICIAL RECORD COPY usam mi-mm

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c, If you have any questions regarding this natter, please cnntact Mr. tiilliam Kane,

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e The application / reporting requirements contained in this letter have been

<d approved by the Of fice of Management and Dudget; OMB Approval No. 3150-0011.

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Sincerely, s

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obert L. Tedesco, Assistant Director e

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for Licensing x

7 Division of Licensing

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Office of Nuclear Reactor Reculation x

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Enclosure:

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Guidelines for Demonstration of Operability of Deep

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Draft Pumps i

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Mr. Louis 0. DelGeorge-l Director of Nuclear Licensing l

Commonwealth Edison Company l

Post Office Box 767 Chicago, Illinois 60690 ccs:.

Mr. William Kortier U. S. Nuclear Regulatory Commission Atomic Power Distribution Resident Inspectors Office Westinghouse Electric Corporation 4448 German Church Road P. O. Box 355 Byron, Illinois 61010 Pittsburgh, Pennsylvania 15230 Ms. Diane Chavez Paul M. Murphy, Esq.

602 Oak Street l

Isham, Lincoln & Beale Rockford, Illinois 61104 One First National Plaza 42nd Floor Chicago, Illinois 60603 Mrs. Phillip B. Johnson i

1907 Stratford Lane i

Rockford, Illinois 61107 l

Ms. Bridget Little Rorem l

Appleseed Coordinator 117 North Linden Street Essex, Illinois 60935 Dr. Bruce von Zellin Department of Biological Sciences Northern Illinois University l

DeKalb, Illinois 61107 j

Mr. Edward R. Crass l

Nuclear Safeguards and Licensin.g Division Sargent & Lundy Engineers 55 East Monroe Street l

Chicago, Illinois 60603 l

l Nuclear Regulatory Commission l

Region III Office of Inspection and Enforcement 799 Roosevelt Road l

Glen Ellyn, Illinois 60137 l

l Myron Cherry, Esq.

Cherry, Flynn and Kanter 1 IBM Plaza, Suite 4501 Chicago, Illinois 60611

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ENCLOSURE GUIDELINES FOR DEMONSTRATION OF OPERASILITY CF DEEP DRAFT PUMP 5 DISCbSSION I.E. Bu11etin '79-15 dated, July 1979, identified problems associated with deep-draft pumps found at operating f acilities and near term operating lice'nsee facilities.

Deep draf t pumps,whic,h are 3 so -

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_ called " vertical turbine pumps; are usually 30 to 60 feet in length

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with impe11ers 1ocated in castng bowls at the lowes.t elevation of

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the pump. The motor (d$ kver) is located at the highest pu=p elevi. tion with the discharge nozzle just.below the motor...-

Bulletin 79-15 was initiated because'several nuclear power plant

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facilities could not demonstrate operab'11 tty of their pumps. Th8.

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pu=ps were experiencing excessive vibration and bearing wear. The" rapid bearing wear suggested that these pumps could not perform their required functions during or following an accident. As a result of the s;aiti s initial review of the responses to IE3 79-15,.

several plants were identified as having potential problems with their deep draft pumps. These guidelines are provided for these '

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

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s, DEEP DRAFT PUMP OPERATING CHARACTERISTICS I,n, order to better understand the. operating characteristics of g-these pugs, a rotor dynamics analyses was perfortred to ascertain the response of the pump. rotor under steady state operation.

The analyses considered journal bearing to. shaft dynamic respcase at various eccentricities and fluid Viscosities.

The model for

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the analysis depict,ed a typical deep draft pump utilized by the nuclear industry.

The analysis resulted in recor:Tnendation,s for ihprovTng the stability of' t'he pump rotor'from externally 'ap' plied

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i nputs' an'd b'y' self ~g^en~erited i~ri;iuts'.

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.:i The conclusions which were derived from the analysis and staff evaluations of North Anna, Beaver Valley and Surry facilities with similar pugs include:

1.)

Pugs with this type of configuration are prone to bearing whirl vibration problems due to the flexibility of the t: tor and casing structure.

This phenomenon is accentuated as journal bearing clearance beco:res large. This phenomenon leads to bearing wear (Journal bearings).

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"1.ow Head Safety Injection Pucp Rotor Dynamic Analyses", by Franklin Research Center, Report FC4982, dated May 1980.

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There may be natural frequencies associated with the pump 2.)

assembly $hich occur near the operating speed of the pu=p.

Pump operation will drive these frequencies and can cause The severity of this condition is dependent bearing wear.

on bearing diametral clearance, rotor unbalance conditions

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and housing flexibility. As an example, if the wear in

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column journal bearings beco:es sufficiently large

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( twice the original diametral cl earance)"'so that these bearings are no long r active and the undamped criticaY frequency near"th'e' operating speed of the pump

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is allowed to expand, the additional uncontrolled bearing This wear can continue until the shaft wear will cccur.

rubs against the support structure of the bearing and can potentially sever the shaft.

One acceptable method for correcting instabilities.in the 3.)

pump shaf t is to utilize a journal 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 vill cause the bearing to form a hydro-dynamic film quickly during startup.

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4.), Stiffening of the column sections of the pump is

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i, advantageous if there is a column frequency near the

_,,, operating speed of the pump.

The shifting of the column frequency to a higher level will eliminate

.,,..any coupling between the pump operating speed and the

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,coiumn irequency.

5.1_ F. low in'let conditions to the pumps and step designs can be important to pump cperabilfEy.' Certain installations have demonstrated flow characteristics which produced

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vortexing at the be11 mouth of the pump. This vartexing

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is due to sump design or sump supply line entrance con-ditions. This condition can contribute to additional pump vibration and wear.. Flow straightener devices, reduction of be11 mouth diameters, and bottom clearance reductions have proven to be effective in eliminating this problem.

6.) This type of pump has exhibited operational problems due to design and installation deficiencies. The high S'.

flexibility of the shaft and column make this design rather forgiving when it comes to installation deficien-cies such as misalignment between the ' shaft and column,

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low-predision coupling assemblies, and non-perpen,dt,cu}ar,

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-- mounting-flanges. This fact however, can. lead to, excessive bearing wear without-significant. noticeable. change. in p, ump operating characteristics..To ensure proper; pump, operation, proper alighment'should.be established._betyeen all. ma,ti,ng

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' surf a'ces and measures should be emphasized:which_ prey l,ent column

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and shaft eccentr'iciti~s. These measurei can include optical e

aligr. ment of th'e ' column segments,: use of high, precision couplings an'd use of-accurate techn-ique,s to est.ab.lish that

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the sump plumb line is perpendicular to the pump mounting fl ange.

The above findings and conc 1usions have contributed significantly to the development of these guidelines. The guidelines listed below are divided into insta11ation and test areas. The subjects to be addre; sed in these areas are considered to be of prime importance when establishing a pump operability assurance program.

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The extent to which each of the two areas are implemented at a l

specific facility is dependent on specific symptoms which have been identified with these pumps while in operation and during service periods.

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. Implementing the t.:easu/es outlined below, at North Anna 1 & 2 in

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. wi1T be operable when' regaired for their safety function. These

. guidelines are not~ intended to replace the requirements o[

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EStandard Review plan 3.9.3,'Re'ulatory Guide 1.68 or any other g

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requirements presently enfofded by tne staff.' Rather, the 4__

guidelines are to be us'ed 'a's~" supplementary material for establishing Meep-draf t pump operability.

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GUIDELINES FOR OPERABILITY IHSTALLATION.

1.0 INSTALLATION PROCEDURES-

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Experience has shown that th.ese pumps-are prone: to having opsability problems as a result of poor installation procedures.

The guidelines.

emphasize those areas of the installation procedure, which if impi mented, '

could significantly improve the. likelihood of an operab1'e pump. The procedures utilized should be submitted to the staff for review.

1.1 pump INSTALLATION Determine by measurement that all shaft segments are straight a.

within tolerances specified by the mafiufactu/er.

b.

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

Determine by measurement that all pump segment flanges are c.

perpendicular to the centerline of the segment, that the segments are straight and that any mating surfaces are

. concentric to an established datum. Mere Journ'ai~ ~ '

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, bearing guides (SPIDERS) are used, establish con-centricity between this assecbly and its mting surface.

d.. Align full pump casing assembly optically tolassure-maxirum stral5htness and concentricity.of;the:asse=bly..

Any.. equivalent rethod is acceptable, as long as the

, procedure. stresses. column ' straightness ~and 'concent'ricity.,- -

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Assure purp;to motor flange perpendicularity and that

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proper coupling installation is perforned.

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Assure that all nating surface bolting is properly attached and that manuf acturer terquing sequences are

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1.2 SUMP INSTALLATION Assure (where used)'that sump /purp mating flange

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. is perpendicular to the sump pump line.

b.

Assure that sump design prevents fluid anccalies such as vortexing or turbulence near the intake i

to the pu=p bellmouth and that incoming piping l

is not so designed as to allow fluid conditions favorable to these anomalies (i. e., sharp. '

bends in piping prior to entrance. into sump).

c.

Assure that interference' does 'not exist between the sump and ary pu=p. appendage such as a seismic restrai nt.

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8-2.0 Testino Recuirements The installation procedures are essential in establishing pump operability.

In addition to carefu'l' install'atio'n, testing may

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be ' required which will verify proper ' operation of these pumps.

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Af ter cogletion of the installation' checks, licensees or appli-cants should evaluate the need 'for 'further'tes' ting an'd irefort

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the.results of this' e'v'aiuation 'togetherI with 't5ie' ~de' tails of any

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test plans to the staff.

Should tests b.e required, an acceptable test procedure should include the 'iteirs listed.h low.

The s'taff recognizes that the instrumentation and procedures outlined b'elow -

may be difficult 't'o i plement at all f acilities and,' theref' rN.. the

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staff is enhasizir[g good insti[lation practices which' lead to operable cogonents.

If tests demonstrating operability cannot encogass all the items listed below, then alternative procedures should be proposed for eYaluation' by the staff. The te5,ts'should emphasize measurement of pug ' dynamic characteristics and wear data at different stages of testing, culminating with an extrapolation of the data to the desired life goal for the pump.

2.1 Test Instrumentation The following instrumentation should be incorporated into the test procedure aside from normal flow measu'rement, pressure and vibration instrumentation:

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9-a.)

X, Y proximity probes at three axial locations on the pump column, for measuring and reco'rding radiaT[6s tfEbs of E

shaf t with respect to the column.

b.)

X, Y, accel'erometers (at proximity probe locations)

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for measuring and recording radial" accelerations of the

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' col mn.

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c.) Dynamic pressure.trans_ducers for_ measuring fluid pressure' I

at _the.following locations :.

1.

Bottom of Column (suction)__

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2.

Mid-Column; a

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

2.2 PRE-TEST DATA k'ith the pump disassembled, measure all jcurnal bearing 0.D.'s, bearing I.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 preper operation of the p, robes.

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3.1 PH'ASE 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)

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This phase of testing should be co= prised of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> of testing: (Sreak-int followed by start-stop testing. ~ Test' conditions.should simulate as nearly as,possible normal C 7' and accident _ conditions..Paramete',rs: to be consideredi:

are flow, temperature, debris, and chemical composition o f ' fl uid: being-pumpedr : Static' torque tes'ts should :be i t' performed-before'and af ter the test (i.e. measure amount of torque : required _to. turn shaf t by hand). Data should be

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

A. total of 12 start-stop tests-will be performed con-i

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sisting of a start up from zero speed up to full-speed, 10-minute dwell at full-speed and ja shutdoyn from full speed to zero speed, with recording of all inctrumentation during full cycle of start-stop.

Upon completion of Phase 1 testing,the following data should.

be obtained and~ recorded:

1.) Obtain the " clearance circles" using the three sets of proximity probes.

2 Tests at North Anna 1 & 2 and Manufacturers input 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 " break in"- -

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2.) _ Measure and record the following dimensionc for each bearing:

a. )' Journal 0.D.

b.) Bearing I.D.

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c.) Bearing to Journal diametral clearance

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d. ) Establish Phase 1 test bearing wear.

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-THE ACCEPTANCE CRITERIA IS AS.FOLLOWS:

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3 1.) If wear is> 5 mils for any bearing, wear is unacceptable c

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and test -should be terminated.

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2.) If wear is( 5 mils for all bearings

a. ) Reasser.ble the pucp i

b. ) Obtain " clearance circles"

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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 test *ng is to be performed at full system pressure.

and terperature and fluid conditions sinulating those expected

. during accident and normal operation.

Before start and at cocpletion of Phase 2 test,obtain measurement of static torque.

Data should be recorded continuously during the start-up period,

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.e 3This acceptable wear value may be modified based on manufacturers reconrendation.

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als'o be rec'orded

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and during the shutdown period. Data shou 1

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at 1-hour time interva1s during the 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> test. -

The following measurerents should be made at-the conpletion of Phase 2 of the test:-

1.). Obtain the " clearance circles." using_ the; three sets of,

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proximity: probes.

Measure and rec::rd the following dirensicps for'each.

2.)

bearing:

a.) Journal 0.D.-

.b. ) _ Sear.ing 1.D.

c.) Bearing to Jcurnal diametral clearance.

d.) Establish accuculated bearing wear.

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THE ACCEPTANCE CRITERIA 15 AS FOLLOW 5:

1.) If accuculated bearing wear en any bearing is

>7 mils, wear is unacceptable and test shculd be t ermi nated.

If accuculated wear en all bearings ish7 mils 2.)

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for all bearings a.)

Reassemble pump

b. )

Obtain " clearance circles" c.) Reinstall pump in test leep.

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1 5.) Phase 3 Testing (96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />) e s

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Phase 3 testing is to.be perfomed at full system pressure-

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and temperature' and fluid con 2 tio'ns simulating th'ose expecteU

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during accident and nomal operat'fon.

The same procedures T

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-should be followed as in Phase 2 testing except that-data ~, ZE']

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- may be taken with less freq'uency. -

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.:-q The same measurements should be taken at the completion of l'~

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this phase as with the other phases with the following acceptance

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1 1.) if accumulated bear'ing. wear is> B ' mils for.any bearing,-

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wear is unacceptable and test should be teminated.

2.)

If accue.ulated wear is ( 8 mils for'all bearings,3, decision needs to be made to establish:

a.)

the need for additional testing or b.)

whether or not the bearing wear will be acceptably low.

' The reccmmende'd decision process is outlined below.

Plot the values of accumulated wear versus time (H) for each

,a bearing 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 /> Wear at H3 = 150 hours0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br />

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Straight lines are then drawn through the plotted values of wear

.7 and extended to the right (See example Figure 1).

If the extension

._. _ intercepts the maximum acceptable value of wear (8 mils) at a Yalue Ji less than the life goal for this pump, additional testing should be perfomed. ;If the intercept of the line with wear of 8 mils exceeds the 11fe goal for this pump, no. additional testing is

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-required and bearing wear g acceptable.

If addition.a1 testing is deemed necessary it should be done in a.similar manner to that

, perfomed during Phase 3 with similar accertance criteria and decisto'n process. It is expected that such additional testing will' either show a stab 1'e pump operation'with no increase in

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bear'ing wear or increased bearing wear with unacceptable results.

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_2.6 Evaluation of Pumo Acceptability

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If bearing wear (af ter all testing phases) is acceptably low (as per decision process) and if vibration levels over 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 its intended use.

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