ML20058H394

Discusses Implementation of Corrective Action When Limitorque Actuators Inoperable Due to Hydraulic Lockup. Mfg Completed Effort to Prevent Hydraulic Lock in Spring Pack

ML20058H394
Person / Time
Site:	Cooper
Issue date:	11/13/1990
From:	Rosenthal J NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
To:	Berlinger C, Marsh L Office of Nuclear Reactor Regulation
References
NUDOCS 9011150238
Download: ML20058H394 (3)

Text

w ny .

,t

+ *> NOV 131990

.~

LMEMORANDUM FOR: Carl H. Berlinger, Chief Generic Communications Branch Division of Operational Events Assessment i Office of Nuclear Reactor Regulation - l Ledyard B. Marsh, Chief -.

Mechanical Engineering Branch Division of Engineering Technology Office of Nuclear Reactor Regulation FROM:- Jack E. Rosenthal, Chief Reactor Operations Analysis Branch ,

Division of Safety Progtams i

Office For Analysis and Evaluation of Operational Data

SUBJECT:

IMPLEMENTATION OF CORRECTIVE ACTION WHEN

' LIMITORQUE ACTUATORS BECOME INOPERABLE DUE-TO HYDRAULIC LOCKUP -  ;

The enclosed LER 298/90-009 discusses an event at Cooper Nuclear Station that involved a a L motor operated valve which failed in a closed position after a pump surveillance test. The motor had failed (burnout) because the torque switch did not open (trip) when the valve 4

w closedJ The cause was attributed to hydraulic lockup of the actuator spring pack. This is a ,

condition where grease accumulates in the spring pack so that the spring can not compress.  ;

j p

Since the spring does not deflect, the torque switch cannot trip so the motor will continue to <!

L run until it overheats and fails. The motor on the reactor core isolation cooling (RCIC) steam 4 l supply valve at the Cooper plant failed in this manner.

For background, the hydraulic lockup issue was addressed by an industry communication in August' 1986 and was reviewed in depth in AEOD Report E702-(Ref.1) issued in March, L 1987. As a result of the AEOD report, the original industry communication was cancelled and a'new communication was released in August 1987. The March 1987 AEOD report o I occurred about 3 months after NRC had requested that NUMARC take the lead for overall j industry action to resolve various MOV problems (Ref. 2). Since !Se industry effort had been ,

L ' initiated,-NRC staff (AEOD, NRR, and RES) met with.NUMARC to discuss whether the

'? spring pack hydraulic lockup problem could be included in the overall industry MOV effort.

y As indicated in Ref. 3, EPRI agreed to accept the task. Subsequently, in' conjunction with '

p EPRI, Limitorque,'Inc, conducted a test program to confirm that modified spring packs did L not exhibit hydraulic lockup during operation. ' Limitorque issued Maintenance. Updates 88-2 a

. and 90-1 to address the hydraulic lockup issue. The latter update provides recommended o011150238 901113 hDR ADOCK 05000298 s PDC

~'

3. .,

-. ', Carl E. Berlingcr '

corrective actions for those actu.ttors which experience lockup. We understand these updates complete the Limitorque action in response to the hydraulic lockup problem. Hydraulic lockup vos luentified on the list of degraded conditions in the MOV Generic letter 8910, but there was no guidance about corrective action.

The corrective action for the event in LER 298/90-009 does not appear adequate to provide assurance against future hydraulic lockup. Further, the stated corrective action is not consistent with Limitorque's recommendation in Maintenance Update 90-1 (issued in May a 1990) which states:

" Actuators which experience hydraulic lock or have a history of motor burnouts should have the spring pack modifications implemented. For older actuators without the internal grease relief path, the external grease relief kit should also be installed."

The steam supply MOV at Cooper Station meets these criteria in that hydraulic lock was ,

identified, the motor failed due to burnout, and the actuator does not have the internal grease relief paths.

AEOD is concerned that the LER from Cooper Nuclear Station could be representative of a  ;

potential generic problem where licensees may not implement the guidance provided in the Limitorque Maintenance Updates because they misunderstand the situation. The last sentence in Section G, Corrective Action, of LER 298/90-009 seems to support this concern with the statement "further action will be considered after the manufacturer has completed the root cause investigation and determined the appropriate corrective action to prevent recurrence." In actuality, we understand the manufacturer has completed their effort to prevent hydraulic lock in the spring pack. Subsequent discussions indicate that Cooper is planning further action on

- hydraulic lock.

The AEOD Report E702 delineated a three step industry effort to (1) identify conditions that result in hydraulic lockup, (2) develop solutions, and (3) disseminate the corrective actions. ~

We believe this event indicates there is a need for a generic communication to assure dissemination of the corrective actions for hydraulle lock to appropriate licensee staff. Either i an information notice or an industry communication could be used in order to ensure communication to the appropriate organization at the plant. Since the last industry 4 communication on hydraulic lock in August 1987 indicated that Limitorque was continuing investigation of the situation, a revised industry communication may be the optimum method to disseminate information that provides evaluation and recommendations to the licensees.

Original signed by Jack E. Rosenthal, Chief Reactor Operations Analysis Branch Division Of Safety Programs Office for Analysis and Evaluation of Operational Data  !

Enclosure:

As stated Distribution: See attached-O ROAB:DSP:AEOD ROAB:DSP:AEOD Cjf' lOAB:DSP: AEOD EBrown:mmk QS MChiramal Q JRosenthal 11//3/90 11/n/90 1If/90

o

'1 1

[ .

l Carl E. Berlinger l

' REFERENCES 1

l- ' l. . U.S. Nuclear Regulatory Commission, E.J. Brown, "MOV Failure Due To Hydraulic L Lockup From Excessive Grease In Spring Pack," AEOD/E702, March 19,1987.

L l

2. U.S. Nu_ clear Regulatory Commission, U.tter to W. Owen, NUMARC, from j V. Stello, Request for initiatives to remedy motor-operated valve performance and l l reliability problems, December 10,1986.~

1

3. U.S. Nuclear Regulatory Commission, J.E. Rosenthal to T.M. Novak, " Summary of 1 1

NUMARC-NRC Followup Meeting to Discuss Motor Operated Valve Hydraulic Lockup Due To Grease In The Spring Pack, February 11,1988. -

1 t l

l l.

1

-l 6

8

w , ,, ,,, o8 vCu.. au. t.iO*, COu %0~

se ati ,,,40v i 0 0.. .o 3,. . ,0 l

Et91Rtl e v tl l

I

,j UCENSEE EVENT tV.PO'4T (LER)

Estimatto eva0t= na ali,0=st to COu ate e Ec'af.*E'ts'Uo*NO",'c'fv10t', E','iuYt t is eftli #IOUS

';'!v"'#0a" CO't.J "0.f'O'Yse' 'n fJit f.M t "

Tat eartaw0au at0vCitom pa0;tCf 01604108 Of fiCl 08 wa8saGtus set aNO ev006 f.naganectoN OC PN3 8 ACitetY haut oi 00 Cast e,venet a ni sacs (3 Cooper Nuclear Station o16lolo1ol2l9[B 1lodOj3

'" Inoperability of the Reactor Core Isolation Cooling System Due to Failure of the Motor Operated Steam Supply Valve Attributed to "pring Pack Hydraulic Lock t ytast patt Ill tin taVaseta 16i alp 0at Oatt iyi Otuta saCitlittl18svotyt0 te, u0a st m Dag vtaa vtan ,a ' 7 WO4t= Cav vtaa 'atinen gawel 00 Cat t erywat a:Si o l 6101 o [ 0 i t i j OjB 0l B ; 9 0 9l 0 0l 0j9 0l0 0lB 3l0 9l0 oistoto,og l 1 l' g tMit al#0nt tt DV8 Miff t0 PVa8Vaast to Tut et wta tef TNT 10810 Cf a { isner8 .ae e, *ere et an. s o .g. ,s git, j as006 im N y agggy g aggi,3 Ogy3,,,qw., j yy 9,y l POWga M 4WieH1Hd W MasHtt 90 f ataH2Hei 13 7 ties

- ~ ~~ """"

"7.' ' 1i 00 i n asei.HiHei w MiaHai w ni.H Hoi Of ut a o .,, .. . .. .

M 4NieH1H4) H nielOHet to 73teH2HowiHal Jagas l n Hin . a n.eiQH., = ni.H:H n.,

30 eetieH1Het M 73te sQlte6H to 73telGHas tiCt8t$tt C08st ACT f 0m f uit (la n3s Naut Tett'M0kt NVueta Donald L. Reeves, Jr. ''

4,0,2 B ,2, $ p 3,5 11 C0esPt t f t 08:4 tisut 80s taCM ComeP0eutNT F AlWat 040Caitt0 sN Tuts alpOnt H3 CAU44 tvstiu Cow'Omthf "$[g aC ne t ,T,ags4 Cault tysttu COUPON 4 %f wj%aC mg e

a X Bt N lFI Cl V L2 l 1 0l0 Y I l t t l l t l l l l l l l 1 l l I l I f

.v.,u ot =,.i al.On, t i,4C,8 0 n.

.0~,- Oa. i.Ian iv. .

0an ns0,.

""} ,n m .. .., ., amCru0 su..aon oau, y ,,0 i a .C 1,-, ,, . . . . . em ..~,,, . . ~ a , n .,

At approximately 3:00 pm, on August 8, 1990, with the plant operating at full power under norma 1' steady state conditions, Reactor Core Isolation Cooling (RCIC) Steam d tion ,

4 se, At the time of failure, the RCIC9ys'tellt \ ras 'o,ut o rvico a "pirt'or t preiftanned evolution to enable troubleshooting and correction of an unrelated problem. The system was not considered to be operable. The surveillance test was being conducted as-a post maintenance test, prior to returning the s see ;o an_ operable condition. ~

Subsequent Tlivesti EFn~ revealed thacTInotirTr t tor Operate'd Valve (MOV)

.had failed d_u.e..co'.?g f

.~.aT1U . re of the CiDSE .tordue Isdi.

-- ch t._o open.

~

The appsr'enMau~seMf the motor failure appears to have been due t 'e lock) of the spring pack..

which was found to be,This 'fu is based upon It is an inspection postulated thatofthe thegreasespiQ p_ , icy prevented springpackcompressich',gofgreaseres'tiltlag ~1h the torque switch remaining closed wh subsequently caused motor failure. The d6torms replse6d; the sprTrifpsiek> ele ~en68t' and the torque switches were verified to operate properly.

This is the first instance of failure of a MOV at CNS that could potentially be traced to a hydraulic lock condition in the spring pack. CNS personnel will continue to participate in industry sponsored investigations and evaluations of MOV problems and concerns. Regarding this p uticular concern, further a M o"n will be

~ -

considered af ter the manufacturer has completed the root,cause investigatios and s determined the appropriate corrective actio~h to prfvent,sgucurrence -, .w w. g .

(;p ym - ..

, a C , .. o . . . . ,

y(, , .

4 g-.m ,,...., m . ,o ,, _ ,

q-

,,,.....n t.lCENSEE EVENT REPORT (LER) ',"6"d,'.',*,c',v%'un'oMo"',* ,' 4"?' .*c'lo'J's ,

TEXT CONTINUATION ,,U'.".'o'f,j's&2j ,',#f'.*d'l'"h'Z"' MN3 i'F,1,'#,,'4;"a=,a=,W Of hf &fsAGile(s ? AND $WOQti A$sein,010m DC 20u4n?%=

e

,acmt, .. m occa n av=**a i2' 6en =vuesa ici eace +

.iaa

" R' M't ' -"'5*.?"  ;

i Cooper Nuclear Station 0 l5 l0 l0 l0 j 2]9 l 8 9l0 _

0l0l9 -

0l0 0 l2 0F l3 ran ,,, . w .. w=acs m m mi l' A. Event Deserlotion At approximately.3:00 pm, on August 8, 1990, Reactor Core Isolation Cooling (RCIC) Steam Supply Valve, R$10 M SD1 W ie in its normally closed position upon being closed foifowing ' success completion of the pump operability surveillance test. At the time of failure, the RCIC System was out of service as part of a preplanned evolution to enable troubleshooting and correction of an unrelated problem. The system was not considered to be L operable.: The s5Pgglance!, test'9as being co " ' tua as a poetaatstemasse -

prior to returnliyi the'sy' stem to an ope (a% t' condition F Subi'e$ liny h.vestigation revealed that the motor for the Motor operated Valve (MOV) had T [a1,10,d;6ue_,tMMQths;g(tofj,ue qeggg i B. Plant Status j operating at full power under normal steady state conditions. ,

C. B.gsis for Report i

A system required by Technical Specifications to be operable and capable of  !

being automatically initiated. Failure of RCIC.MOV.M0131 in the closed position was, therefore, considered reportable in accordance with 10CFR50.73 (a)(2)(v). ,

1 D ,1 gaung The a parent cause of the motor failure

'~n i to have4egpGarto' hydraulte- ~

_ . poo ' jaEEERIingTyacki The spffiEE ' .

was inIp"ected iindhund to be full It is' postulate'd I&at the grease prevented spring pack dompr' , . esulting in-the torque switch remaining closed, which  !

subsequently caused motor failure.

E. Safety Stanificance lione. As specified in'the bases for paragraph 3.5.0 of the Technical Spscifications, RCIC_is designed to provide makeup to the nuclear system as  ;

part of the planned-operation.for periods when the main condenser is

unavailable. The nuclear safety analysis, USAR Appendix C, shows that.RCIC provides water to reestablish and maintain reactor vessel water level (and

' thereby provirie for core " cooling") when feedwater is lost. As noted in.

Appendix C, in the discussion section associated with isolation of all2 steam lines, pressure relief corchined with loss of feedwater flow causes reactor vessel water level to fall. At high pressures, the High Pressure Coolant

= Injection (HPCI) or RCIC System supplies warar to maintain reactor _ vessel water level to provide for core cooling .m normal steam flow (or other planned operation) is established. Further, as noted in the discussion

-section associated with loss of feedwater flow (in Appendix C), either the HPCI or the RCIC System can maintain adequate water level, and together, these systems satisfy the single failure criterion for core cooling. During the time frame when RCIC MOV M0131 was out of service, HPCI was fully operable.

' ^ h 5N[4e at Gwg.Ip5'1Ah,4wMahn '

~ ~ ~ ~ ~

c j.mm.,qng h s ~ .'*=oveo ews .o a cion 3

'. 'ates e,3ose: -

' I --

f,U6't,U,7,o'"

• Min'"on'oMi,'tci",'y ,*c'A'"'!

i l LICENSEE EVENT REPORT (LERl L

TEXT CONTINUATION i,,ny,'3V,15,'#?,,',g*i*d',gll1,'M '",' $.!gj ,

L c ,, !"

i',P,,'%..

o m.. ..*.n..tt.i,',c*i,'. o

0. ;..?a,,'J*

.... oc #,,,t, ?,3 f.citety a,a,,g ni DOCRif NUM9t h (21 ggg ,gynggg g ig, p g. ..

"a "t!W. ",'J,?.?" i l

Cooper Nuclear Station 0l0l9 or o pl0l0l0l2[9l8 9l0 0l0 0l3 ')

[3 rare nr . w. , =ac a assav nn F .' Safety Imolientions None. As noted in the preceding discussion, when the main condenser is unavailable, makeup water can be provided by either RCIC or HPCI. In all other postulated accidents and transients, no credit is taken for the RCIC

, System. In such cases, HPCI provides makeup water to the reactor when not depressurized. The Automatic Depressurization System (ADS) in conjunction with the low pressure core cooling systems provide redundancy for the HPCI System, should it not be capable of performing its safety function.

G. Correctihe Action The niotor .was replaced, the spring pack cleaned, and the torque switches were-verified to operate properly. The RCIC pump operability surveillance test was l

successfully completed, and at 11:25 am,- on August 9,1990, the RCIC System was restored to.an operable condition. .

This is the first instance of failure of a MOV at CNS that could potentially be traced to a hydraulic lock condition in the spring pack. The motor operator manufacturer, LimitofMCorporation, has been itWHT.gati reported Mc13ents of this nature and has identified several factoEs'"B,T se the donalhllianlof experiencing this pit 6tione*h'on. However, available int ation to date indicates that o eo ek k to be of a 1

f e. OpWipers'onne ill_ cont nue to '. ry l;

T investlistions and evaluations of MO pro ens and con ns.

l.

I n(tihis'ppr n will-be .

ter the l ceufer has7c,ticular' cene~ern, ompleted the root caus " ~ '

an

'~"

he

[, '

'agepriagrreptg'acttinaggipr .

4 H. Similar Events ,

None, i

'I. Sucolemental Information RCIC.MO M0131.is a -Limitorque SMB 00 Actuator with a force rating of -10 f t lb, driven by a 125v DC, 1900 rpm motor, mounted on a 3 inch, 900 lb Anchor Valve

. Company globe valve.

EIIS System Code BN EIIS Component Function Code - FCV

,,1c

• m e sv l

, x ., .

3 .

COOPC R' NUCLE AR ST Af ton  !

Nebraska Public Power District

• • E*c",2?#sU,'?."i?""'" '

w-l CNSS903822'

-August 30, 1990 l

• t i

s U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555

Dear Sir:

Cooper Nuclear Station ' Licensee Event Report 90 009, Revision 0, is being (

forwarded as an attachment to this letter. ,

Sincerely, t

i J L'M. Meacham-Division Manager of Nuclear Operations Cooper: Nuclear Station-JMM:bjs Attachment.

Martin i

~

cc: 'R.-D C.:R., Horn  !

R'. E. Wilbur.

V; 1., Wolstenholm=

l D, A'. Whitman 4 INPO Records Center, ,

ANI Library NRC Resident Inspector-R. J . Singer.

CNS Training >

CNS Quality' Assurance-

't 4

^I S*

O 9 1d .U .8

.;j gG I/ QT*'8 . D' was30 '74 $

pop ADOCL .,.r,ggQ P *DC- [g2 2 l

l 4 .

} lll i 4- ,

. g ,. 7

Carl _ E. Berlinger .

" iDISTRIBUTION:

PDR

Cesi$fPil6'?

ROAB R/F EBrown.,

MChiramal

' ' JRosenthal EJordan '

Dross - '

- I> - , TNovak ,

T VBenaroya

[

. .LSpessard -

. GZech .

9~'

SRubin

, ' MWilliams -

. RSavio,' ACRS

MTaylor, EDO g-

. KRaglin,7TC -

- AChaffee, NRR PO'Connor, NRR TScarbrough, NRR RKiessel, NRR ORothberg, RES:

CRossi,.NRR '

s

JRichardson, NRR;

=

m P

E'

=

M.

% .i 1

==

_ DFo 3 m