ML20115K068

Auxiliary Feedwater System RISK-BASED Inspection Guide for the Catawba Nuclear Power Plant

ML20115K068
Person / Time
Site:	Catawba
Issue date:	09/30/1992
From:	Gore B, Moffitt N, Vo T Battelle Memorial Institute, PACIFIC NORTHWEST NATION
To:	Office of Nuclear Reactor Regulation
References
CON-FIN-L-1310 NUREG-CR-5827, PNL-7726, NUDOCS 9210290084
Download: ML20115K068 (31)

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AVAILADILITY NOTl *s Anwey or Nfererce Listenals CrteJ n IMC Putdcatorm Most documents tited in N40 putucations w$ be aval'abic ftofte one of the fohowing source 6' 1 The Nhc Pubtit Docurrent Room 2120 L Ltreet, NW. , Lower Lent, Washington, DC 205%

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in9pettIDn and invettlpAUDn n>tice6. k eh9ee 8,ent r epQrtta' vendbr r ep'>rt h and corre'bpondenc e. CDmm16+

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Documents c$eunble from the National Techracal Inf orrnation Servke includo NURE G se'iet reports and techng al report 6 plepined by othef tider Al 00Dnties and repbrts prepared b/ the Atomic Enr#gy CommiS-tion, forerunmr agency to the Nuclear hegulatory Comnusion Documents, avvable from pubhc and specia! te'chtscal l&r anes include all open hieratura, items, aut h as book a , loumal alik.len, and tr antac hant I cuera! Hepto notitt v, i ederM anct State leg %lat6pn, 69d con.

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NUltEG/ Cit-5827 l'NI.-7726 Auxiliary Feedwater System Ris<-Based Inspection Guide for the Catawba Nuclear Power Plant Manusenpt Completed: Apul 1992 I) ate Published: September 1992 Prepared by N. !!. Moffitt,11.17. Gore, T. V. Vo Pacific Northwest laboratory Richland WA 49332 l'repared for Division of IIndiation l'rotection and Emergency l'reparedness Olrice of Nuclear lleactor llegulation U.S. Nuclear llegulatory Commission Wasliington, DC 20555 NilC FIN 1.1310

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l Summary This document presents a compilation of auxiliary feedwater (AFW) system failure information which has been .

screened for risk significance in terms of failure frequency and degradation of system performance. It is a risk.  !

prioritired listing of failure events and their causes that are significant enough to warrant consideration in inspection planning at the the Catawba plant. *lhis information is presented to provide inspectors with increased resources for inspection planning at Catawba.

'Ihc risk importance of various c mponent o f ila ure modes was identified byanalysis of the results of probabilistic11sk assessments (PRAs) for many pressurized water reactors (PWRs). However, the cornponent failure categories identi.

ficd in PRAs at rather broad, because the failure data used in the PRAs is an aggregate of many individual failurcs having a variety 6.1 root causes. In order to help inspectors focus on specific aspects of component operation, main.

tenance and design which thight cause these failures, an extensive review of component failure information was performed to ldent!fy and rank the f oot causes of these component failures. Iloth Catawba und industry wide failure information was analyzed. Failure causes were sorted on the basis of frequency of occurrence and seriousness of consequence, and categorized as common cause failures, human errors, design problems, or cotoponent failures.

'lhls information is presented in the body of this document. Section 3.0 provide brici descriptions of these risk-important failure causes, and Section 5.0 presents more extensive discussions, with specific examples and references.

'lhe entrics in the two sections are cross referenced.

An abbreviated system walkdown table is presented in Section 3.2 which includes only components identified as risk important. This table lists the system lineup for normal, standby system operation.

This information permits an inspector to concentrate on components important to the prevention of core damage. ,

llowever,it is important % note that insp:ctionuhould not focus exclusively on these components. Other compo i

nents which perform essential functions, but which are not irs.i.uded because of high reliability or redundancy, must also be addressed to ensure that degradation does not increase their failure probabilitics, and hence their risk importances.

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i Contents I 111 Summary.....................................................................................

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1.1 1 I n t r od u ct io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 Ca t aw ba A FW Sys t e m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 .

i 2.1 Sys t e m Descr i pt io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 2.2 S uccess Cr i terio n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - 2.2 ,

2.3 Sp lem De pe nde ncies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 2.4 O pera t io nal Oms t ra i n ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 3 Inspection G uidance for the Catawba AFW Sptem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . 3.1 3.1 Risk important AFW Components and Pallure Modes . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 3.1 3.1.1 Multiple Pump Pallures Duc to Q)mmon Cause . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . 3.1 3.1.2 Tb rbine Driven Pu mp Pails to Start or R un . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 3.1.3 Motor Driven Pump A or B Palls to Start or Run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 3.1.4 Pump Unavailabic Due to Maintenance or Surveillance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 3.1.5 Air Operated Flow Omtrol %1ves Fall Closed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.1.6 Motor Operated Isolation %kes Pall Closed ........................................... 3.3 3.1.7 Manual Suetion or Discharge Wlves Rail Closed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 3.1.8 leakage of 1109t Feedwater through Check Wives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , 3.4 3.2 Ris k Important AFW System Walkdown Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.4 .

4 G eneric Ris k i nsights From P ras . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 4.1 Risk Important Accident Sc<luences involving AFW System Pailure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 4.1.1 Ims of Power Spt e m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .............................. 4.1 ,

l 4.1.2 tansient. Caused Reactor or Tbibine ' Rip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1-l 4.1.3 less of M ain itedwate r . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1

. 4.1.4 Steam Generator 'lbbe Rupture (SOTRL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.1.

4.2 Risk Important Component Pallure Modes ..... ........... ............................... 4.1

- 5 Failure Modes Determined hom Operating Experieno: .......,. ...................... .......... - 5.1 l.

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5.1 Ca tawba Expe rie nce . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 l.

5.1.1 M ult iple P ump Pallures . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 5.1.2 Motor Driven Pump Pallures .. . . .-. . ................ ...... . .. ............. . ..... - 5.1 -

- 5.13 'Ibtbine Driven Pump Failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . ... .... .... 5.1

' 5.1.4 Flow Cont rol and Isolation Wlve Pailu res . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 v' NUREG/CR.5827-i I

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1 1 Intratluction  :

'lhls doeurnent is one of a series providing plant specific The temainder of the document describes and discunes inspection guidance for auxiliary feedwater (Al'W) the information used in compiling this inspection guid-systemut pressurized vater reactors (PWRs). This ance. Section 4.0 describes the risk importance infor. I guidance is based on information from probabilistic risk mation which has been derived from PRAs and its aucuments (PRAs) for similar PWib, industry-wide sources. As review of that section will show, the failure operating experience with A14V systems plant specific events identified in PRAs are rather broad (e.g., pump AFW system descriptions, and plant. specific operating fails to start or iun, valve fails closed). Section 5.0 experience. It la not a detailed inspection plan, but addresses the specific failure causes which have been rather a compdation of AISV system failureinformation combined under these broad events.

which has been screened for risk significance in terms of failure frequency and degradation of sysicm perform- AIAV system operating history was studied to identify ance. The result is a fisk prioritized listing of failure thevarious specific failures which have been aggregated events and the causes that are significant enough to war- into the PRA failure events. Section 5.1 presents a tant consideration in inspcetion planning at Catawba. summary of Catawba failure information, and Sec-tion 5.2 presents a review of industry wide failure infor-This inspection guidarice is prescated in Section 3.0, fol- mation. The industry wide information was compiled lowing a description of the Catawba Af4V system in Sec- from a uriety of NRC sources, including AEOD analy-tion 2.0. Section 3.0 identifies the risk important sptem ses and reports,infortnation notices, inspection and com}xments by Catawba identification number, followed enforcernent buhetins, and generic letters, and from a by brief descriptions of ca( T of the various failure causes variety of INPO reports as well Some 1.icensee Event of that component. These include specific human Reports and NPRDS event descriptions were also errors, design deliciencies, and hardware f ailures. De reviewed. Finally,information was included from l

.4 discussions al.so identify w here common cause failures reports of NRC sponsored studies of the effects of plant have affected multiple, redundant components. These aging, which include quantitative analyses of repored brief discussions identify specific spects of system or _ AIAV system failutes. This industry-wide informa1on cee ponent design. operation, maintenance,or testing was then combined with t he plant 4pecific f ailurc infor-for inspecilon by observation, records review, tra:ning mation to identify the various root causes of the broad observation, procedures review,or by observation of the failu*c evera n.ed in PRAN w hich are identified in implementation of procedures. An AFW system walk. Section 3.0.

down table identifying risk important components and their thicop for notmal, standby system operation is also provided.

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Contents Summary................................................................................... 111  !

1 I n t r od u ct io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 2 Ca t a wba AFW Sys t e m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 r 2.1 Sys t e m Descri pt io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 -

2.2 S u ccess Cri t e rio n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2- '

23 Sys te m De pende ncies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 2.4 O pe ra t io nal Co n s t rain ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 3 Inspection Guidance for the Catawba AFW System . . . . . . . . . . . . . . . . . .. . .. . . .. .... . . . . . . ........ 3.1 3.1 Risk Irnportant AFW Components and Bilure Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 3.1.1 Multipic Pump Failures Due to Common Cause . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 3.1.2 'Ibrbine Driven Pump RL a Start or Run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 3.13 Motor Driven Pump A or B Pails to Start or Run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 3.1.4 Pump Unavailable Due to Maintenance or Surveillance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 3.1.5 Air Operated Flow Control Wives Pall closed . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . 33 e

3.1.6 Motor Operated Isolation W!;cs Ril Closed ........................................... 33 i 3.1.7 Manual Suction or Discharge Wives Fall Closed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 3.1.8 Leakage of 11091 Fecdwater t hrough Check %1ves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ' 3.4 ~

3.2 Risk Important AFW System W.kdown Thble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 4 Oc neric Risk insights From PRAs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 4.1 Risk important Accident Segences involving AFW Sptem Failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 . .

I t 4.1.1 1. ass of Powe r Sys t e m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. '.4.1 4.1.2 'D ansient-Caused Reactor or Wrbine Trip , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 4.13 Loss o f Ma in Feed wa t e r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 4.1.4 Steam Generator 'Ibbe Rupture (SGTR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 4.2 Risk Important Component Failure Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 5

5 Riture Modes Determined From Operating Experience . . . . . .. .. . , . . . . . . . . . .. . . ... . . .. . ......... 5.1

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5.1 Catawba Experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . . .. . . .. . .. . . . .. . . ...... 5.1 5.1.1 M ultiple Pump Rilures . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . .. .. . . . . .. . ... .... 5.1 -

'5.1.2 Motor Driven Pump Wilures . ... . . ... ..... ....... ...... ................. . ..... 5.1 5.13 Wrbin : Driven Pump Pallures . .. . . . . . . . . .. . . . . . ., . .. . . .. . . . . .. . .. .. ....... 5.1 5.1.4 Flow Control and Isolation Wlve Rilures .... ......... .. . . . ... . .. .. . . . ...... . 5.1 ~

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5.1.5 Ch ec L %1ve Fail u r cs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 .....

0. l .6 I l u ma n Erro rs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.2 ..

5.2 Ind us try4 Vide Experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 5.2.1 Common Cause Pallurce .. . . . . . . .. .. . ................................................ 5.2 5.2.2 i l u m a n Erro rs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.4 ....

5.2.3 Design /Enginecring Problems and Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4 5.2.4 Co m pone n t Pa ll u r es . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . 5.5 0RCICrCoces.................................................................................... 6.1

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3.1 Risk importan t AFW s,ystem walkdown table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 1 NUREG/CR-5827 si y > -m-y e a m vawrm w--m- r :n

1 Intrmluction This document is one of a series prosiding plant-specific The remainder of the document desenbes and discuwes the information used in compiling this inspection guid-inspection guidance for auuliary f eedwater ( AFW) ance. Section 4 0 describes the rist importance infor-systerns at preuurized water reactors (PWits). This puidancc is based on information from probabilistic ri'l mation w hich has been derived from PI(As and its sources. As review of that section will show, the failure aucuments (PRAs) for similar PWRs, industry. wide evcnts idenufied in PRAs are rather broad (e.g., pump operating experience with AISV systems, plant specific 1 ails to start or un, valve fails (losed). Section 10 AFW system descriptions and plant-specific operating addresses the spccific f ailure causes whkh have been experience. It is not a detailed inspection plan,but rather a compilation of AISV system f ailure infortnation cornbined under these broad cventt which has been screencd for risk significance in ter ms of f.ulure frequency and degradation of system per f or m.

AFW system operating history was studied to identify ance. The result is a risk-prioriti/cd listing of failure the various specific failures whith have been aggregated events and the causes that are significant enough to war- mto the PRA f ailure events. Section 5J presents a tant considesation in inspection planning at Catawba. surnmary of Catawba failure information, and Sec-tion 5.2 presents a resiew of industry wide f ailure infor-mation. The industry wide information was compiled The inspection guidance is presented in Section 10, fol-lowing a description of the Catawba AFW system in Sec- trom a variety of NRC sources, including Al?OD analy-tion 2.0. Section 3.0 identifies the risk important system ses and reports information notices, inspection and enforcement bulletins, and generic letters, and frorn a components by Catawba identification number, followed variety of INPO reports as wcti. Some I icensec !? vent by brief descriptions of each of the various failute cact es of that component. These include specinc human Reports and NPRDS esent descripiions were also errors, design dciiciencies,and hardware failures. The reviewed. Finally,information was includcd Irom discuwions also identify where common cause failures reports of NRC sponsored studies of the effects of plant have affected multiple, redundant components. These aging,which include quantitative analyses of reported brief discussions identify specific aspec ts of system or AFW system f aihnes. This industry wide infortnation was then combined with the plantapccific f ailure infor-component design. operation, maintenance, or testing mation to identity the various root causes of the broad for inspection by observation, raor ds review, trainmg observation, procedures review,or by observation of the failure events used m PR A% which are identified in implementation of proccdures. An AFW system walt- Section 3 0.

down table identifying risk important components and their lineup for normal, standby system operation is also ptovided.

1.1 N U R1:G!CR 5X27

2 Catanl>a AliW SySteia

'nik seuion presents an meniew or the Catawha AFW circulating water system (RC). Power, control, and sysicm (Westinghouse 4 loop platit), including a simpli. Instrumcntation associated with each train are inde-hed schematic system diagram. In addition, the system pendent from each other Steam fot the turbine drhen suaew criterion, system depend (ncies, and adniin. pump is supl. lied thnmgh S A 2 and S A.5 Itom steam htiative operalional constiaints atc aho presented. generators li and C, hom a point upstream of Ihe inain steam isolation vahes. Ila(h Al'W pump i equipped with a rec iculation flow system which prevents pump deadheading.

2.1 SyStel11 l)('SCrllltioll The dtubarres of the motot dtnen pumps are notmally The AUW syuem pnwides feedwater to the steam rener.

abrned so that the A pump supphes the A and 114 cam alors (SO) to allow secondary-side heat iemov.d f rom generators and the Il pump supplies the C and D steam the primary sysictn when main leedwater b unavailabic.

generators. Croscronnect valves are provided to allow The system is capable of f unctioning for utended letding of any stram generator !!oin either pump The periods, whit h allows time to icstore ruain feedwater erowconneu valves are lot ked shut and adminktra.

llow or to proceed wtth an orderly couldown of 1he plant thcly (ontrolled. The turbine driven pump can aho to where the icsidual heat removal (RllR) system can feed all four steam generators, but through separate remme decay heat. A simplified st hematic diagr am ot lines. The bloc k vahes to steam generators A and D the Catawba AFW system n shown in Firute ? 1.

(CAMll,38A) are not mally closed to prescut turbine.

dnven pump runout in the event of two steamline rup-The systern is designed to start up and estabhsh flow tures. The motor drhen pumps are protected liom run-automatically. All pumps start on receipt of a sicara out conditions by a high flow proteuion circuit, if putnp penciator low low level signal. (The motor-driven diuharge flow f eat hes 780 rpm for 30 seconds on either pumps start on low law lesel in one SG, wherto, two pump A or 11,it closes S/G 11 or C discharge kolation 50 low low level sir ah ate tequired for a turt ine, vahn respedively. Steam generator inlet isolation diiven pump start.) The motor-drhen (MD) pumps Vahes are locked open manual vahes and the dNharre start for the following conditions: safety injettio- blacL.

holation vahes are motor operated.1/ low controlvahes out, loss of both feedwater pumps, and AMS AC (N! WS in each of the eight feedwatcr lines are pneumatic I!ach Mitigation System Actur' inn Citeuitry). The single tme aho contains multiple check vahes to present leak.

tuibine.diiven (TD) pump stat ts on an undenoltage age frorn the feedwater lines.

condition on either 4160 voll essential bus The Condensate Storare System (CSS),which is cotu-The preferied soutre of Al/W pump tuction is f rom the prbed of the CST, Upper Surre'lhnk and Condenser condenute storare rank (CST), wnh alter nate suction Hotwell, Ptovides the normal suction soutees for the soutres from the upper surre tant (UST) and the con AFW system and is requited to slme sullicient wate: to densct hotwell, A tommon header supphes water to maintain the teactor coolant system (RCS) at hot stand both the motor durch and tutbine-drhen putnps by for two houts followed by a cooldown to the point through a t hc(L vahe and a noIn.all) open motor con.

where RilR wstem can be placed in service. All tank trolled isolanon valve. Two adihtional back-up sources connedions except those required for instr utnentation, of water for the Al2W pumps are ptmided flom the auuliary feedwater pump suction, and tank drainage are nuclear sen ice water system (RN) and the condensci located abose this minimum level.

2.1 Nt!Ri{G C R A s27

Catawba Al'W System 2.2 SLlecess Criterioll aw>aaled flow paths are operable with each inotor-drnen purnp lH>wered from a dificient emef fency bus.

by.hrn suurss requnes the operation of at least onc  !! orie A13W purnp becornes inopcf able,it must be purnp supphHir takd flow to two sicam rentratots. restored to operabic status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or the plant snust be shut down to hot standby within the next sh hour %. ll two A17W puinps ate itioperable, the plant inuu be shut down to hot uandby within six houts.

2.3 SyNieill I)cpell(lelicies With three Al'W pumps inoperable, correctlW action to r Mo' at au one purnp to operabit' Matus tnust be

'Ihc Al/W system 0cponds on AC power for motor. '"'" ' " " ' " " I' drist n pumps and rootor conttolled isolation sabes,l>C pou r for tonitol power to purnps, vahts,aad auto. , . . . .

b 4 IUalfe at luation slp'thlis,innd j[ist[urntill ait (g! Aj/W ,

our upply of water to e noted in the Condensate flow top"al vah es In addinon, the turbine driu n " i' "bC I" pulop alst) regulles stealn aVdilatillitV. -

able,it snust bc testored to operable status wuhin four hours or the plant must be shut down to hot standby within the neu six hours. !! the nuclear setsice water

~.4 ()perinflutlill C,ullstr;tlIlts pond is dernonstrated to be operabic,it may serve as a backup AITVsupply for seven da)s before plant shut.

W, ben the scactor e unicalihr Catawba ln hnical down is required.

$pt ahc;itions require that all three Al:W purnps and c

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3 Inspectiori Guitlarice For The Crittmlia AFW System in this sn tion the Ink important tomponents of the 3.1.1 Mtilliple l'untp l' allures 1)ue to cataaba AFW systs m are identihed, and the important Corninon Cause f ailute modes fo! the(c components are briefly dew (nbed These f ailot" modes include spetihc hunmn The following hstmg summarizes the niost important t nors, design dcIniencic% and 1) pes of hardware f ail- tnultiple pump f ailure gnodes identified in Section .21, urcs whic h have been observed to occur for these win ~ Common Cause Failures and each item is Leyed to ponent ., both at Catawba and at pWRs ihroughout the entries in that section.

nutlear todustry. He disc uolons also identity where common cause failures base af f ected inultiple, redun. .

mconect opeiator intervention into autorr"ic sys-dant componerits. These brici diseuusons identify speci- 1em furctioning, including imptoper manual start-Oc aspnis of sysicm or component desen, operanon- mg and securing of pumps, has caused f ailute of all rn,antenamc. or testing for impection activities. These pumps, meluding overspeed trip on startup, and ina-activities include: observanon, recoids review, traininf bdity to restart prematurely secured pumps CCl.

observanon, protedures lesiew, or by observation of the implen otation of procedures.

• Valve mispositioning has caused failure of all pumps. Pump suction steam supply,and instru.

'lable 31 n an abbreviated AFW tystern walldown table inent isolation valves have been involved. CC2. At whkh identifies risk-imponant components. This table Catawha, control switch mispositioning has ren.

hsts the system hneup for normal (standby) system oper- dered both of the motor doven pumps inoperable anon. Inspection of the coinp.ments nienufied m the while the turbine driven pump was out of service.

AFW waltdown table addresses essentially all of the rist associated with AFW syneni operation. . Steam binding has caused failure of multiple pumps.

This resulted from leakage of hot fredwater past clieck valves and motor-operated valves into a com.

3.1 }{ISk llilport:1 tit AFW CoriiporteritS mon discharge header CC10. Multipic. pump steam binding has also resulted from improper valve inittl F:iiiiire Mmles lineups, and trorn running a pornp deadheaded.

CC3, Common cause f ailures 01 multiple pumps are the most sisk.important failure modes of AFW nstem compon- .

• pump control circu.it denciencu or desig., modifb ents. These are followed in importance by sincle pump cation errors have caused failures of multiple pumps f ailures, level control valve failurcs, and mdiviIlual check to auto start, spurious pump t'ips during operation, valve leakace failures.

and f ailures to restart alter pu tp shutdown. CC1.

inconect setpoints and control circuit calibrations The followine, sections address each of these failure have also prevented proper operation of multiple modes,in de$reasme order of risbimportance. Rev '

pumps. CC5.

present the importa'nt root causes of these component f ailu:e modes which have been divilled from historical

• ss of a viud power bus has failed both the tutbine.

rccords. Each item is Leved to discussions in Secuon 5.2 driven and one motor-driven pump due to loss of where dditionalinformanon on histornril events is presented, control [ower to steam admission valves or to tur.

Fne c.'ntrols, and te motor controls powered from the same bus. CCC 3.1 NURECECR.5S27

Inspection Guidance

• Simultaneous startup of multiple pumps has caused bumping it, failure to reset it following testing. and oscillations of purnp suction pressure causing failures to verify control room indication of reset, snultiple pump trips on low suction pressure, 11112. Whcther either the overspeed trip or TIV despite the existence of adequate static nel positive trip can be reset without resetting the other, indica.

Suction head (NPSl1). CC7, Design reviews have lion in the control room of TfV position. and uro identified inadequately slied Suction piping which ambiguous localindication of an overspeed trip could have yicided insullicient NPSil to support affect the likelihood of these errors. Dli3.1 allure operation of more tLm one pump. CCK of the overspeed trip linkage to reset due to linkage hinding has occurred at Catawba.

3.1.2 'thrl>lne Driven Purnp Falls to Start or Itun Stress corrosion cracking caused failure of the - 'i turbine drhen putnp at Catawba,when the final -

• linproperly adjusted and inadequately maintained stage sha!! S!ceve became f riction welded to the turbine governors have caused purnp failures.11E2. stationary final stage picec of the pump.

Problems include worn or kiosened nuts, set screws, j linkages or cable connectiom, oll icaks and/or con. 3.l.3 Motor Driven Punip A oril Falls to Start I tamination, and electrical failures of resistors, tran. or l{un '

shtors. diodes and circuit cards, and erroneous grounds and connections. Cl 5. Improperly

• C4mtrol citeutta used for automatic and inanual )

adjusted governors have occurred at Cataw ba. pump starting are an important cause of rnotor drivert pump failures, as are circuit breaker failures.

"Ibtry tuidnes with Woodward Model !!G gover- CF7. Control circuit failures have prevented auto, nors have been found to overspeed trip if f ull steam maric pump starts at Catawba, flow h allowed on startup. Sensitivity can be reduced if a startup steam bypass valve h sequenced

• Mhpositioning of handswitches and procedural to open first. del. Jeficiencies have prevented autornMic pump start.

11113. Misposilloning of handswitches has occurted '

• lbibines with Woodward Model PG.PL governors at Calaw ba.  ;

have tripped on overspeed when restarted shotfly atter shutdown, unicss an operator has locally exer-

• Low lubrication oil pressure resulting from heatup I ched the speed setting knob to drain oil from the due to previous operation has prevented pump 'l governor speed settinglinder (per procedure). restart due to failure 10 8athfy the protective  !

Automatic oil dump valves are now available interlock. DlI5.

through ^lbtry. Dl?4, 3.1.4 Punip Unnvallaine Due to Mnintennnce ,

• Condensate slugs in steam lines have caused turbine or Suncillance overspeed trip on startup. 7tsts repeated right afict such a trip may fail to indicate the problem due to

• Doth scheduled and unscheduled maintenance warming and cicating of the steam lines. Surveil-remove pumps from operability. Surveillance lance shouhl exerche all steam supply connections.

requires operation with an altered line up, although DE2.

a pump tram may not be declared inoperable during '

C testing. Prompt scheduling and performance of

'llip and throille valve (TIV) problems which have '

maintenance and surveillance minimize this failed the turbine driven pump include physically umvaibbihtp NUltliO/CR 5527 3.2

,me, m - ,e v ,-m .m-----

p-, '-..n, ,e-n,- g- y w , p ,

i , 1 L-Inspection Guidance i

i EucIcar Servicester Suetion Iwlat_igu 3.1.5 Air Operated Flow Control Wives Fall 15 A.I16A.18pg[} }

Closed [S_S Suct19tdolatlon: CA.2y.7ASildjA i

AFW Wmyrfing13pw Isolatienrn IDAmp.]}gim,.gpq:g,733 CA L85.186.187,1.M ,

MP Pomn31ainu %m4pyg.g These MOVs isolate flow to the steam generators and '

Thoc normally closed air opetaled vahes (AOW) con. provide AIM pump suction isolatiort. 'Ihc discharge ,

trol flow to the steam generators. They faH open on loss isolation valvo and CST suction valves ate normally ofinstrument Air. open and the nuelcar service water suction valves arc norrnally closc4 They all fall as is on loss of power,

• Omtrol circuit problems have ticen a primary cause of failures, both at Catawba and elsewhere. CIN. i

• Cornmon cause failure of MOW has occurred at

% Ivc failures have resulted frorn blown fuses, faH. Qitawha and elsewhere, from failute to use elec.

ute of conttol components puch as current / trical signature tracing equipment to deter mine '

pneumatic convertors), broken et dirty contacts, proper settings o' torque switch and torque switch .

mhaligned or blohen limit switches, control power bypau switches. Failure to calibrate switch settings loss, and calibration problerns. Degraded opetalion for high torques necessary under deslgn basis aed.

has also resulted from improper air picshure due to dent conditions has also been involved. CCl1.

the wrong type of alt regulator being installed oi '

leaking air Uncs.

• Wlve motors have been failed due to lack of or improper sie.ing or use, of therrnal overload protec-

• Out of. adjustment electric:d flow controllers have tive devices. liypassing and oversiting should be caused improper valve operation, aflecting multiple based on proper engineering for design bass condi-traim of Al/W. CCl2. Catawba has espetienced Horn. CF4.

problems in individual trains.

• Out-of. adjustment elecificed flow controllers have

• Leakage of hol feedwater through check valves has caved improper discharge valve operation, caused thermal binding of flow control MOW, affecting multiple trainsof AIM. CCl2; AOW rnay be similarly susee, Uble. CF2. Catawba l has experienced these types of failuies.

• Glease trapped in the torque switch spring pack of the operators of MOW has caused motor burnout

-* Inadequate air pressuic regulation at Citawba has or thermal overload trip by preventing torque swit.ch resulted in control vahe failure to operatc.

actuation. Cl%.

• Multipic flow control valves have been piogged by l

• Manually leversing the direction of motion of oper.

clams when suction switched automatically to an  ;

adng MOW has overloaded the motor circuit. '

alternate, untreated sourec. CCg Operating procedures should provide cautions, and citeuil designs may prevent reversal before cach 3.1.6 Motor Operated Isolution Wlves fail stroke is finished < DE7, Closed

[

• Space heaters designed for preoperation storage MD pumpyisibarce isolationd have been found wired in parallel with valve motors

- CA-4?ll 4 fill 58Ah2A which had not been emironmentally qualified witht l-Ip Pump Dischatgq]splation' t. hem present, DE8; WJA,50A.MiUAll ,

33 NtJRl!G/CR 5827 -  ;

Inspection Guidance 3.1,7 Manual Suction or Discharge Valves Fall .

Failure to provide casily read system drawings, Close(I legible valve labch corres[mnding to drawings and procedures, find labeled indications of local TD Pump "Dain: CA 14;21:6 151.47.35 valve position.

MD Pump'Itains A:IU CA 25MS7M:50.55.4333

~

3.1.8 Irakage ofIlot Feetlwater through These manual valves are normally locked open. Ibr Check Valves each train, closure of the first valves would block pump suction, closure of the sec(md valves would block pump MD Pumn'ltains A:th CA-61.57;CA-45JJ1.,

('ischarge and closure of the third set of valves would TD.ptnp Tiain: CA.65,53.49.37 block discharge to steam generators A,11, C,and D, respectively.

• leakage of hot feedwater through several check .;

valves in series has caused steam binding of multiple '

• Vahr mhpositioning has resulted in failures of mul. pumps. Leakage through a closed level control tiple trains of AFW, CC2. It has also been the valve in series with check valves has also occurred, i dominant cause of problems identified during oper. as would be required for leakage to reach the motor ational readiness inspections. HEl. Events have driven or turbine driven pumps CCIO occurred most often during maintenance, calibra-tion, or system modifications, important causes of a Slow leakage past the final check valve of a series mispositioning include: may not force the upstream check valve closed.

Other check valves in series may leak similarly.

Failure to provide complete, clear, and spccific Piping orientation and valve design are important procedures for tasks and system restoration factors in achieving true series protection. CFl. .

lititure to promptly revise and validate proce-dures, training, and diagrams following system 3,2 ((lgk [gnggjg tant AlrW Systern modifications gg . ,gg Failure to complete all steps in a procedure

'!hble 3.1 presents an AFW system walkdown table Failure to adequately review uncompleted pro, including only romponents identified as risk important.

ceduralsteps after task completion This information allows inspectors to concentrate their cflorts on components important to prevention of core Failure to verify support f unctions after restora, damage, llowever,it is essential to note that inspec-tion tions should not focus exclusively on these components.

Other components which perform essential functions :

Failure to adhere scrupulously to administrative must aho be addressed to ensure that their risk impor-pro (edures regarding tagging' control and track. :ance are not increased. Exampic; include the (open) ing of valve operations steam lead Hop check valves SA-3 and 6, energizing the heat tracing on the AIM turbine steam supply and an Failure to log the manipulation of scaled valves adequate water level in the CST liiilure to follow good practices of written task assignment and feedback of task completion, information NUREG/CR-5827 14

- --Ia.n a w .,.er-.a ,---w.a- ,+-#.,-n,. w. . - _ ., ,,. m .-e-t-ess- n :en e -

-r= ? t. 1--3-T+-T f~M'"'(FpTT 7'F"'TT'"T'TW'mT-

Inspection Guidance table Al itisk imlwwtunt AIMystern Walldown Tuhle itequired Actual Comlwment Name l'osition l'osition Comininent #

I;lectrical A Motor Driven Pump Racked in/

Closed il Motor Driven Pump Racked in!

Closed Y91Le cAJ? CA l'MP Suction I rom iITW1.1501 Open eA4 CA PMP Suction 17:om UST Open CA-ri CA PMP Suction litom CA CST Auto!Open CA 7A CA Pump No. I Norm Suction ISOL Open CA- Al CA Pump 111 Notin Suction 1S01. Open CA-11A CA Pump 1 A Norm Suction ISOL Open CA-1$A CA Putnp 1 A Suction 1 rom RN ISol, Auto / Closed CA 1811 CA Pump 111 Suction 17:om RN ISOL Auto / Closed CA 8511 CA Pump No.1 Suction 1 rom RN IIDR 11 Auto / Closed g.

CA 1lbA CA Pump No.1 Suction 1: rom RN IIDR A Auto / Closed CA-171 RC to CA Suction 1S01. Closed CA- 175 RC to CA Suction ISOL Closed CA- 17X RC Supply to CA Pumps ISOL Open CA 19 CA Pump No.1 Suction 1S01. Incked Open CA-25 CA Pump 1 A Suction ISOl. Incked Open CASO CA Pump IB Suction ISOL locked Open 3.5 NUREG/CR 58'?

inspection Guidance

'llible 3.1 (Continued)

Itcijoic ed Attual Componcut # Component Name l'osition Position CA J.' 1 UA Pump No.1 Mini Flow to UST locked Open Dome ISOL

( A 29 CA Pump 1 A Mini Flow to UST Dome laxLcd Open ISOL C A- 31 CA Pump til Mini Flow to UST Dome Iacted Open ,_ _

ISOL CA 21 CA Purup No.1 Dncharpe to S/G I.ocked Operi CA 87 CA Pump 1 A Discharge to S/G ISOL locked Open CA Kh CA Pump 111 Discharge to S/G 1501 law ked Open

('A-3s CA Pump No 1 Dmharge to S/G ID 1 octed Open Contiol Inlet ISOI. ,

i CA 17 CA Pump iso 1 Dncharge to S/G IC Lot ted Open _ _ _ _ , _

Contiol Inlet ISOL CA 51 CA Pump No.1 Disc harge to S/G lit law Led Open __,_

inlet 1501

('A M CA Pump 1 A Dis (harpe to S/G 111 Inlet 1.ocked Opeu __

ISOL C A- .59 CA Pump 1 A Discharge to SMi I A l o( Ln.1 Open __

Control inlet 1501.

a CA-39 CA Pump 1B Disch to S/G ID 1 xx ked Open _ _ _

Control Irilet ISOl

(' A U CA Punip IB Disch to S/G IC LotLed Opeu __

Control lnlet ISOL

('A Id CA Pump No.1 Dhch to S/G 1 A Locked Open _

Contial inlet 1501.

CA 111 CA Pump 1 A A til Disch X Oscr to Closed _ _ _

S G 1501.

N1iRLGl( R 5827 3h l

m _., . . -..... _ _ .. .. . . . . _ - . _ _ _ _ _ . _ . . . - ._. ___. _ . _ ._. __.. . _ . _ _ _ . _ _ . _ _ . _ .

I ~ inspection Guidance i

Table 3.1 (Continued) -  :

Required Actual l l-Component # Cost.ponent Name l'osition l'osition -1 Closed CA 112 CA Purup 1 A & 111 Disch Lover to S/O 1S01, CA-40 CA Pump 111 Flow in S/G 10 Oleui _

CA.44 CA Pump llillow to S/O IC Open CA56 CA Pump 1 A Flow to S/G lin Open . _ . , _ i CA .60 CA Pomp 1 A filow to S/G 1 A Open CA 36 CA Pump #1 Flow to S/O 1D Open CA-18 CA Purnp # 1 l' low to S/O IC Open CA32 CA Pump #1 Flow to S/G 111 Open -i t

CA-64 CA Pump #1 Flow to S/G 1 A Open CA 62A CA Pump 1 A Dist harge 1o S/G 1 A ISOL Open CA-58A CA Purup 1 A Discharge to S/G 1.11 ISOL Open -

'CA.46tl CA Pump IB Discharge to S/G IC ISOL Open CA-4211 - CA Pump 111 Discharge to S/O 1D ISOL Open CA50A CA Pump #1 Discharge to S/G 1C ISOL Open

_ CA-54 B . CA Pump _#1 Discharge to S/G lit 1S01; a Open __

CA 3SA CA Pump # 1 Discharge to S/O I'D ISOL Closed _

CAMB CA t' ump # 1 Dvharge to S/G I A (SOL Closed j: ,

CA-1S5 S/G 1 A CA Noule 'Rmpering ISOL .

~Open- _ _ _

CA-186 SXi 1B CA Nonle Tempering ISOL - Open . ,

n Open  :

CA 187 S/G 1C CA Noale Tempering ISOL CA-188 S/G ID CA Nonle 'Ibmpering ISOL Open 37' NUlti!G/CR-5827 ' '

q s

Hi" -

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Inspection Guidabte

'Ibble 3.1 (Continued) llequired Actual Comggment # . Comgwment Narne Position Pmition

-i 1

SA.6 S/O IC SM to CAPT Stop Che(k taked Open '

SA-3 S!G 111 SM to CAPT Stop Check jaked Open SA 2 S/G lit SM te CAPT ' CirAcd SA 5 S/O IC SM to CAPT Closed CAPT'llip and Throttle Valve Open CA 37 Piping Upstream of Check Valve < 160 F ]

CA-41 Piping Upstream of Check Valve < 160

• F CA 45 Piping Upstream of Check Valve -<160 F

' CA-49 Piping Upstream of Check Valve <1(Al+F CA53 Piping Upstream of Check Valve <!60*F .

i CA-57 Piping Upstream of Check Valve <1rAl F  ;

CA 61 Piping Upstream of Check Valve < l(dl F i i

CA-65 Piping Upstican' oicheck Vahe < ltd) F i 'i i

l r

P NUREG/CR-5827 38'

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a -

,' - 6 i

S._.<-, . _ . . _ .c_._..___...,__. ...c..u,-...,, ..u;-.._,. , . . , __;-_.c..._,..,..,, _ _ ..; _1 . _ _ _ _ , . ..

l I

4 Generic Risk lusights Front PRAs PR As for 13 PWRs were analyzed to identify risk. 4.1.3 l>iss of Main l'cedwnter important accident sequences im-t ng loss of ARV, to identify and ristprioritize the u.g ~ iailure im>de. . A, fes_yter line break drains the common inwived. The results of this analyse are described in water source for MRV and AFW, The this section. They are consistent with test i ts reported operators fail to provide feedwater from other by INEL and llNL (Gregg et al.198S; Travis et al.1988). sources, and fail to initiate feed and-bleed cooling, resultF ;in core damage.

4,1 Risk Important Acci(lent Sequences - A loss of main feedwater trips the plant, and AFW fans due to opaatm enor and hardware Involving AFW System Failure failures. The operators fail to nutiate feed and-bleed cooling, resultine,in core d mage. '

4.1.1 1.oss of Power System

• " I

• A loss of oftsite power is followed by failure of ARV, Due to lack of actuating power, the

• A SGTR is followed by failure of ARV.

powet operated relief valves (PORVs) cannot Coolant is lost from the primary until the be opened preventing adequate feed-and. bleed refueling water storar,e tack (RWST) is emling, and resulting in Core dan.: ce. depleted. Iligh press'ure injection (IIPI) fails since recirculation cannot be established from

• 6 stanon blackout fails all AC power except the empty sump, and core damage results.

Vital AC from DC insertors, and all decay heat removal systems except the turbine-driven ARV pump. ARV subsequently fails due to battery depletion or hardware failures, resulting in a-4.2 Risk luiportant Component F,n.i lure damage. M0(leS

• \ i >C bus kil i, causing a trip and failure of the The generie component failure modes idi niified from power conversion system. One AFW motor- PR A analyses as important to ARV system failure are driven pump is failed by the bus loss, and the listed below in decreasing order of risk ir portance.

turbine-driven pump fails due to loss of'urbine or valve cortrol power. AFW is subsequently 1. lbrbine Driven Pump Pailure or Stntt or Run.

lost completely due to other failures. Feed-and-bleed cooling fails because PORV control is 2. Motor. Driven Pump Failure to Start or Run.

lost, resulting in core damage.

3. TDP or MDP Unavailable due tc Test or 4.1.2 Transient-Caused Reactor or Turbine Maintenance.

Trip

4. ARV System Valve Failures -

• A transient-caused trip is followed by a loss of a

• steam admbsion valves the power conversion system (PCS) and AFW.

Feed-and-bleed tooling fails either due to failure of the operator to initiate it,or due to a trip and throute valves hardware failures, resulting in core damage.

1.1 NUREG/CR.5S2'

Generic Risk Insights From PRAs

• flow control valves In addition to individual hardware, circuit, or instru3 ment failures,cach of these failure tuodes may result

^

• pv ?p discharge valves common causes and human errors. Common wu>e failures of AFW pumps are particularly risk

• pump suction valves important. Valve failures are somewhat less impor-tant due to the multiplicity of steam generators and

+

valves in testing or mair.tenance, connection paths. Human errors of greatest risk -

importance involve: failures to initiate or ccntrol S. Supply / Suction Sourecs sptem operation when required; failure to restore proper system lineup after maintenance or t: sting; condensate storage tank stop valve and failure to switch to alternate sources when required.

hot well inventory

+ saction valves.

1 5

0 r

)

NUREG/CR 5827 .t .2

~ _ __ _ _ _ - _- _ __ - __-_ _ _ - _ _ _-_- ____- __ - __-_____-___-_______-___ -__ - _ _ _ _ _ . . .

5 Failure Modes Determined From Operating Experience This section describes the primary root cause of AFW 5.1.2 Motor Driven l'unip Failures sysicm component failures, as '.etermined from a review Joperating histories at Catawba and at other PWRs There have been two events that have resulted in failure Il-ah. ' *c nuclear industry. Section S.1 describes of the motor driven pumps. Failure mode in both cases

'awba from 1985 to 1990 Section 5.2 involved control circuit problems.

sun,aw ation compiled from a variety of NRCs ding AEOD analyses and reports, 5.1.3 hrbine Driven Pump Failures s, inspection and enforcement bulle-tas, and from a variety of INPO Fdteen events have occurred that have resulted in

.me Licensee Event Reports and decreased operational readiness or spurious starting of

,criptions were also reviewed. Finally, the turbine driven pump. Failure modes involved fail-n included from reporic 'f NRC- ures in instrumentation and control circuits, pump hard-sponma studies of the effects of plant aging,which ware failures, cerrosion, mechanical wear, and human include quantitative analysis of AFW system failute failures during mamtenance activities. Improper or reports. This information was used to identify the vuo.- in; dequate maintenance has resulted in high outboard ous root causes expected for the broad PRA-based fail' bearing temperatures requiring pump shutdown and ure events identified in Section 4.0, resulting in the repa r. Stress corrosion resulted in lockup of the tur.

inspection guidelines presented in Section 3.0. bine pump shaft.

5.1.4 Flow Control and Isolation Valve 5.1 Catmvba Experience Failures The AFW system at Catawba has experienend failures 01 Approximately ninety-five events have resulted in the $ FW pumps, pump 110w control and discharge iso' mpaired operational readiness of the air and motor lation valves, turbine trip and throttle valves, and operated flow control valves, and motor operated isola-nuclear service water backup supply valves, and numer- tion valves. Pr.ncipal failure causes were equipment aus system check valves. Failure modes include electri wear, corrosion, instrumentation and control circuit fail-cat, instrumentation and control, hardware failures, and ures, valve hardware failures, and human errors. Valves

~

human errors. have failed to operate properly due to blown fuses, fail-ute of control components (such as 1/P convertors),

5.1.1 W ' tiple Pump Failures broken or dirty contacts, misaligned or broken limit switches, control power loss, and operator c2 cation There have been two incidences of mispositioned problems. Iluman erres have resulted in improper switches either preventing auto pump start or rendermg control circuit calibration, limit switch adjustment, and the AFW system inoperable. In one event, both motor installation of the wrong type of air pressure regulator driven pumps failed to start on demand due to misposi- for propc r valve operation.

tioned auto-start defeat switches. The otber event insolved placing the control switches for the nucicar ser- 5.1.5 Check Valve Failures vice water suction to the motor driven pumps in closed posinon while the turbine driven pump w; More than iony events of check valve failure have of service, making the entire system inoperabic. occurred. The predorninant failure rnode cited was f

51 NUREG/CR 5827 1

Failure Modes normal wear and aging, howeser, abnormal strew result. the steam and feedwater rupture control system ing hom inadequate desip appheation was cited as the (SFRCS) led to overspeed tripping of both turbine-cause for ctd vawe f ailure in several instances. dnsen AFW pumps, probaby due to the introduction of condensate into the AFW turbines from the long, 5.1.6 Ilumitri n' rrors unheated steam supply lines. (The spfem had never been tested with the abnormal, cross connected steam There have been approximately fif teen events allecting supply lineup which resulted.) in the Trojan event the the AFW system since 1985. Personnel have inadver operator imorrectly stopped both AFW pumps due to tently actuated the AFW pumps during testing, ininated misinterpretation of MFW pump speed indication. The AFW pump suction swapover to nudear service water, diescidnven pump would not restart due to a proiecthe and mispmitioned control switches during operation. feature requiring complete shutdown, and the turbine-lloth personnel error and inadequate procedures have dnven pump tripped on overspeed, requiring local reset been involved. Misunderstanding of operabdity requite. of the trip and throttle valve. In cases where mar -

ments has resuhed in equipment eweeding lechnical intervention is requurd during the carly stages of a tran-Specitication tunits, sient, training should emphasite that actions shouhl be e performed methodica!h and deliberately to guaid against such errors.

5.2 ludustry-Wide Experience (T2. Whe mispositioning has accounted for a signifi-Iluman errors, design /encincering problems and errors, cant traction of the human errors failing multiple trains and component failures are the primary root causes of. of AF%,. .I.Im. . includes dosure of normally open suction AF%, System failuies idenu, tied in a review of industry valves or steam supply salves, and of. . isolation vahes to sensors havint ccattol functions, incor rect hand 3witc h wide system operating hbtory. (,ommon cause t.ailurts, -

w hich disable more than one tiain of this operahonally positioning and inadequate temporary wiring changes redundant system, are highly risk significant, and can have ah" prevented automatic starts of multiple pumps.

resuh from all of these causcs. Factors identified in studies of mispoutioning errors mdude f ailure to add newly m. stalled valves to valve

.l'his secuc n identifies imponant common cause tailare checklists, weak administratise control of tag'ning, resto, modes, and then provides a broader discimion of the ration, independent verification, and locked valve log-single failure etlects of human errors, desien< emg. and inadequate adherence to proecdures. lilegible

~

or conf usmg local valve labeling. and insutlicient train-engineermg problems and errors, and cotnponent lad-utes. Paragraphs presenting detaih of these fadute my in the determination of salve poution may cause or ..

mask mispositioning, and surveillance w hich does not mcdes are coded (e.g., CCl) and ciowre!.crenced by inspection itt.ns m Section 3 cstn he complete systein f unctioning r ty not reveal umposmom n gs.

3.2,l COillition Catise l' allures CCJ At ANO 2, both AFW pumps lost suction due to steam bmthng when they were lined up to both the CST The dominant cause of AFW system multiple.uain f ail' and the hot startup biowdown demineralizer elfluent urcs has been human error. Design /engmecting enors (Ah0D/Csi 1984). At Zion-1 steatn created by run-and component f ailures have been ! css hequent, but ning the turbine dnsen pump deadheaded for one nesertheless signdicant, causes of multiple train ladures minute caused trip of a motor-doven pump sharing the wmt udet head ( r,as well as damage to the tutbine-0 11 lluman error in the form of incorrect operatot dnwn pump (Region 3 Morning Repoit,1/17MI). lioth intervention into automanc AFW system funcoonmf events were caused by procedural inadcrcies dunng transients resulted in the temporary be of all

} safets grade AF% pumps duringesents at Davis Besse tM Design / engineering errors have act ounted hn a (NU R FG- 1154 1985) and Trojan ( AEOD T41614S3 )

unaller, but ugmticant fracnon of wmmon cause In the Dmis itesse event, improper manual mithlion ol NUREG,CIW7 5?

Failure hk> des failures. Problems with control circuit design modifica- tiple pump failure due to cavitation. Subsequent tions at Farley defeated AFW pump auto-start on loss of reviews at Robinson identified a loss of feedwater tran-m:un feedwater. At Zion-2, restart of both motor driven sient in which inadequate NPSIi and Hows less than pumps was blocked by circuit tailure to deenergi/c when design values had occurred, but which were not recog-the pumps had been tripped with an automatic start sig- nized at the time. Event analysis and equipment trend, nal present (IN 82 0119S2). In addition, ARY control ing, as well as surveillance testing which duplicates ser.

circuit design reviews at Salem and Indian Point have vice conditions as much as h practical, can help identify identified designs where tailures of a single (omponent such design errors.

could hase f ailed all or multiple pumps (IN 87J119X7)

M Asiatic clams caused failure of two ARV flow CQ incorrect setpoints and control circuit settings control valves at Catawba 2 when low suction pressure resulting trom analysis errors and latlutes to update pro- caused by starting of a motor-drhen urup caused suc-tedures have aho prevented pump start and causeet tion source realignment to the Nuclear Service Water pumps to trip spatiously. Frtors of this type may system. Pipes had not been routinely treated to inhibit remain unitetecicG despite surveillance testing, unles clam growth, not regularly monitored to detect their survcillance tests model all typet of system initiation presence,and r.o strainers were installeo. The need for and operatmg conditions. A greater traction of instru- 5 utveillance which exercises alternative system opera mentation and control circuit problems has been identb tional inodes, as w ell as complete system functioning, is tied during actual sysicm operation (as opposed to sur- emphasized by this event. Spurious suction switchover scillance testmg) than tot other types of failures. has aho occurred at Callaway and ai McGuire, although no failures resulted.

M On two occasions at a foreign plant, failure of a balance of-plant inverter caused failure of two AFW CC10; Common cause failures have aho been caused by pumps. In addition to loss of the motor driven pump component failures ( AEOD/C4041984). At Surry-2, whose auxiliaty start relay was powered by the invertor, both the turbine driven pump and one motor driven the turbine driven pump trip;3ed on userspeed because pump were declared inoperable due to steam binding the governoi valve opened, allowing full steam Cow to caused by backleakage of hot water through multiple the tuibine. This illustrates the importance of assessing check valves. At Robin ~un-2 both motor driven pumps the ef fcets of laitures of balance of plant equipment weie found to be hot, and both motor and steam driven which supports the operation of critical components. pumps were found to be inoperable at different times.

The instrument air system is another esample of such a llackleakage at Robinson-2 passed through closed sys tem - motor-operated isolation valves in addition to multiple check valves. At Farley, both motor and ttabine driven CC7. Multiple AFW pump trips have occurred at pump casings were lound hot, although the pumps were Milktone 3, Cook-1, Trojan and Zion 2 (IN 87-531987) not dec'ared inoperable. In addition to multi-train fail-caused by briel, low pressure oscillahons of: ction pres- utes, numerous incidents of single tram failures have sure Juring putnp startup. These oscillations occurred occurred, resulting in the designation of" Steam Binding despite the availability of adequate static NPSI1. Cor- of Auuliary Feedwater Pumps" as Generic Issue 93.

rective actions taken include: estending the time delay This peneric issue was resalved by Generic Letter 8X-03 associated with the low pressure trip, ternoving the trip, (M:raglia 1988),which required licensees to monitor and replacing the trip with an alarm and operater AFW piping temperatures each shift, and to maintain ratica procedure.s f r recognizing steam binding and for restoring system operabihty.

O Design errors discovered duting AFW system re-analysis at the Robinson plant (IN 84-3019S9) and at Ell Common cause failures have abo failed motor Millstone-1 resulted in the supply header f rom the CST operated valve,s. Durmg the totalloss of fe, Mater being too small to provide adequate NPSII to the event at Davh Besse, the normally open AFW isciation pumps if more than one of the thrce pumps were oper- valves failed to open altet they were inadvertently ating at rated flow conditions This could lead to mul- closed. The failure was due to improper setting of the 5.3 N UREG/CR-5S27

Failure Modes torque switch bypass switch,which prevents motor trip errors associated with the trip and throttle valve. TIV on the high torque required to unscat a closed valve. associated errors include physically bumping it, failure Previous problems with these valves had been addressed to restore it to the correct position after testing, and by increasing the torque switch trip setpoint-a fix which failures to verify control room indication of TrV posi-failed during the event due to the higher torque required tion following actuation.

due to high differential pressure acrcss the valve. Simi-lar cornmon mode failures of MOVs have abo occuned 1.jin Motor driven pumps have been failed by human

, in other systems, resulting in issuance of Generic Letter enors in mispositioning handswitches, and by procedure 8910,

• Safety Related Motor-Operated Valve Testing deficiencies.

and Surveillance (Partlow 1989)." This generic letter requires licensees to develop and implement a program 5,2.3 Design / Engineering Problents and to provide for the testing, inspection and maintenance Errors of all safety-telated MOW to provide assurance that they will function when subjected to design basis del. As noted above. the majority of AFW subsystem conditions.

failures, and the greatest relative system degradation, has been found to result from turbine-driven pump fail.

CCl?. Other component failures have aho resulted in utes. Overspeed tQs of Terry turbines contre 11ed by AFW multi-train failures. These include out-of' Woodward governors have been a significant source of adjustment electrical flow controllers resulting in these failures (AEOD/C6021986). In many cases these improper discharge valve operation, and a lailure 01 oil overspeed trips have been caused by slow response of a cooler cooling water supply vahes to open due to sill Woodward Model EG governor on startup, at plants accumulation.

where full steam flow is allowed immediately. This over-sensitivity has been removed by installing a startup 5.2.2 Utinian Errors steam bypass valve which open; first, allowing a control-led turbine acceleration and buildup of oil pressure to Hill. The overwhelmingly dominant cause of problems control the governor valve when full steam flow is ideutified during a series of operauonal readiness evahb admitted.

ations of AFW r/ stems was human performance. The majority of these human perfotmance problems resulted DE7 Overspeed trips of Tbtry turbines have been from incomplete and incorrect procedules, particularly caused by condensate in the steam supply lines.

with reapect to valve lineup information. A study of Condensate s'ows down the tu bine, causing the -

valve mispositioning events inmiving human error gosernor valve to open farther, and overspeed re. ults identified failures in administrative control of tagging before the governor valve can respond, after the water and logging, procedural compliance and completion of slug clears. This was determined to be the cause of the steps, verification of support systems, and madequate loss.of.all AFW event at Davis Besse (AEOD/bO2 proccJ 2res as important. Another study found that 1986), with condensation enhanced due to the long valve inispositioning events occurred most otten during length of the cross-connected steam lines. Repeated maintenance, calibration, or mothfication activities. tests following a cold-start trip may be successful due to insufficient training in determining valve position, and system heat up.

in administrative requirements for controlling valve positioning were important causes, as was oral task D12 Turbine trip and throttle vahe (TfV) problems assignment without task completion feedback are a sigmfeant cause of turbine drisen pump failures (IN Ma). In some cases lack of TFV position indica-IlE2. Turbine driv:n pump lailures hau been caused by tion in the control room prevented recogniuon of a human errors in cahbrating or adjusting governor speed tripped TfV. In other cases it was possible to reset wntrol, poor governor mamtenance. incorrect adju3t - cither the overspeed trip or the Tl V without rescuing ment of gosernor valve and oserspeed trip linkages and the other. Tlns problem is compounded by the fact that NURECECR4827 54

Failure hbdes parallel to the Class 1E 125 V DC motors for several the position of the overspeed trip hnkage can be mis.

leading, and the mechanism may lack labch indicating AFW valves (IR 50-489/89-1h 50-499/89-11 1989). The valves had been environmentally quahlied, but not with when it is in the tripped position ( AEOD/CIO21986). ted heaters energized.

the non-safety-r Dij4; Startup of turbines with Woodward Model PG-PL governors within 30 minutes of shutdown has 5.2.4 Com, .ietti Failures re3ulted in overspeed trips when the speed setting knob was not exercised locally to drain oil f rom the speed C;eneric issue llE61,"In Situ Tesiog Of Wlves"was daided into four sub-issues (Beckjord 19X9), three of setting cylinder. Speed controlis based on startup with which relate directly to prevention of AFW systern com-an empty cylindcr. Problems base involved turbine rota-tion due to both procedure violations and leaking steam. ponent failure. At the request of the NRC,in situ test-Terry has marketed two types of dump vabes for auto- ing of check valves was addressed by the nuclear matically draining the oil alter shutdown ( AEOD/CN12 industry, resulting in the EPRI report,

• Application Guidelines for Check Valves in Nuclear Power Plants 1986).

(Brooks 19SS)? This extensive report provides infor-At Calvert Chih,a 1987 loss of.olisite-power event mation on check valve applications, limitations, and required a quwk, cold startup that resulted in turbine inspection techniques. In situ testing of MOVs was trip due to PO.Pl.gosernor stability problems. The addressed by Generic Letter 89-10/ Safety Related short-term conective action was installation of stiller Motor-Operated Valve Testing and Surveitlance" buffer springs (IN 884191988) S1rvetllance had always (Partlow 1959) which requires licensees to develop and been preceded by tutbine warmup,which illustrates the irnplen,ent a program for testing, inspection and main-importance of testing which duplicates service condi- tenance 01 all safety related MOVs. " Thermal Overload Protection for Elcetnc Motors on Safety-Related tions as much as is practical.

Motor Operated Valves - Generie issue !!E6.1 DES. Reduced viscosity of pear boy mi heated by prior (Rothberg 1988)" concludes that valve motors should be thermally protected, yet in a way which emphasites sys-operation caused failure of a motor driven pump to start due to insulficient tube oil pressure. Lowenag the pres- tem lunction over protection of the operator.

sute swiwh seipoint solved the problem,which had not been detected dunny testing. M The common-eause steam binding effects of check valve leakage were identified in Section 5.2.1, entry CC10. Numerous single-train events provide additional DEg Waterhammer at Palhades resulted in AFW line -

and hanger damage at both steam generators. The AFW insights into this problem. In some cases leakage of hot sparrers are located at the normal steam generator levci, M1 W past multiple check va! es in series has occurred and ate f requently covered and untovered dunng lesel because adequate valve-seating pressure was limited to Huetuations. Waterhanuncts in top-feed-ring steam the valves closest t i the steam generators (AEOD/C404, generators resulted in main feedline rupturt at Maine 19S4), At Pohinson, the pump shutdown procedure was Yankee and feedwater pipe clackmg at Indian Point-2 changed to delay cMsing t he MOVs until after the check valves were seated. At Ihrley, check valves were (IN 84-321o84).

chanyed from swing type to hit type. Check valve re-work has been donca* a number c plant

• Different Ilf2 Manually reversing the direction of motion or an valve designs and manutacturers are insolved in this operating valve has resulted in MOV failures where such loading was not considered in the design problem, and tecurring leakage has been expet(enced,

( AEOD/C6031986) Control circuit design may prcsen- esen alter repair and replacement.

this, requiring stroke cornpletion before teversal.

CEL At Roniason,Imating of motor operateu valves by DI% At each of the units of the South'lhas Project, check valve leakage has caused therinal bindmg and fail-ure of AFW discharge valves to op n on demand. At space heaters piovided by the sendor for use in pre.

installation storage of MOVs were f( und to be wired in Davis Besse, high dillerential pressure ccross AFW

$3 NU REG /CR-$S27

(

t

- - - . - - - - - - . . - , - -- -_---_.n, . , - .- - .--

Pallure Modes injection valves resulting frem check valve leakage has failures, and oil contamination due to poor maintenance prevented MOV operation (AEOD/C4031986). activities. Governor oil may not be shared with tutt>ine

~

lubrication oil, resulting in the need for separate oil Q1 Gross check valve leakage at McGuire and changes. Electricalcomponent failures included transis.

Robinson caused overpressurization of the Al%uc- tor or tesistor faiturcs due to moisture intrusion,:

tion piping. At a foreign PWR it resulted in a severe erroneous grounds and connections, diode failuresfand Waterhammer event. At Palo Verde 2 the MFW suction a fauhy circuit card.

piping was overpressurized by chcck valve leakage from {

the AFW system (AEOD/C4041984), Gross check CF6. Electrohydraulically operated discharge valves valve leakage through idle pumps represents a potential have performed very poorly, and three of the five units diversion of AFW pump flow. using them have removed them due to recurrent fail-ures. fhilures included oil leaks, contaminated oil, and '

01 Roughly one third of AFW system failures have hydraulic pump failures.

been due to valve operator failures,with about equal failures for MOVs and AOVs. Almost half of the MOV

~

Cf'7. Control circuit failures were the dominant source failures were due te motor or switch failures (Casada of motor driven AFW pump failures (Casada 1989).

1989) An extensive study of MOV events (AEOD/C603 'fhis includes the controls usM for automatic and. .

1986) indicates continuing inoperability problems manualstarting of thepump as opposed to the instru. 4!

caused by- torque switch / limit switch settings, adjust. mentation inputs < Mast of the remaining problems were ments, or failures; motor burnout; improper sizmg or due to circuit breaker failures, use of thermal overload devices; premature degradanon related to inadequate use of protective devices; damage Cf'S. *flydrauliclockup"of Limitorque SMB spring due to misuse (valve throttling ulve operator hammer- packs has prevented proper spring compression to actu-ing); mechanical problems (loosened parts, improper ast .ite the MOV torque switch, due to grea;c trapped in the sembly); on the torque switch bypass circuit _ improperly spring pack. During a surveillance at Trojan, failure of-installed or adjusted The study concluded that current the torque switch to trip the TfV motor resulted in trip-l- methods and procedures at many plants are not ade- ping of the thermal overload device, leaving the turbine quate to assure that MOVs will operate when needed driven pump inoperabic for 40 days until the next sur-l under credible accident conditions : Speenfically, a sur. veillance (AEOD/E7021987). Problems result from

) veillance test which the valve passed might tesult in un. grease changes to EXXON NEBULA EP-0 grease, one

l. detected valve inoperability due to component failure of only Iwo greases considered environmentally quah-l (motor burnout, operator parts failure, stem disc sepa- fied by Limitorque, Due to lower viscosity, h slowly l ration) or improper positioning of protective devices migretes from the gear case into the spring pack.

i (therrnal overload, torque switch, limit switch). Generic Grease changeover at Vermont Yankee affected 40 of --

Letter 89-10 (Partlow 1989) has subsequently required the older MOVs of which 32 were safety related. Orcase licensees to implement a program ensuring that MOV relief kits are needed for MOV operators manufactured - -

switch settings are maintained so that the valves will ' before 19751 At Limerick, additional grease relief was -

operate under design basis conditions for the life of the required for MOVs manufactured since 1975 MOV r.e-plant. furbishment programs may yield other changeovers to -

EP-0 grease, q51 Component problems have caused a significant number of turbmc driven pump trips (AEOD/C602 CPU For AFW systems using air operated valves, 1986)J One group of events involved worn tappet nut almost half of the system degradation has resulted from faces, loose cable connections, loosened set screws, failures of the valve controller circuit and its instrument improperly latched TfVs, and improper assemNy. inputs (Casada 1989). Failutes occurred predominantly Another involved oil leaks due to component or seal at a few units using anomatic electronic controllers for NLiREG!CR-5827 5.6 E

. - _ , ., %v .- e* *v- ~ ' '

Failure Modes the flow controlvalves,with the majority of failures due inspections have identified inadequate testing of check to electrical hardwatc. At 'lbrkey Point 3, controller valves isolating the safety-reLled portion of the IA sys-tem at several utilities (1xtter, Roc to Rkhardson).

malfunction resulted from water in the Instrument Air Generie I citer 88-14 (Miraglia 19SS), requires licensees system due to maintenance inoperability of the air to verify by test that aireperated safety-related corn-dryers.

CI:ltt l'or systems using oiesel drisen pumps, rnost of ponents will perform as expceted in accordance with all the tailures were due to statt control aml governor speed design basis events, including a loss of notInal IA.

control circuitry. Ilalf of these occurred on demand,as opposed to during testing (Cauda 1989).

01 11. l'or systems using AOW, operability requires the availability of instiutnent Air, backup air, or backup rutrogen. I hrsever, N RC Maintenance Team 5.7 NUREG/CR-5827

6 References Beckjord, E. S. June 30,1989. Closcout of Generic Issue A1:GD Reports li.E61, *In Sint Testinp of ihlves'. Lxtter to V Stello, Jr., U S. Nuclear Regulatory Commission, Washington, AEODIC404. W. D. Lanning. July 1984. Stcom Binding D.C,. ofAurillary1%cdwater Pumps U.S. Nuclear Regulatory Commission, Washington, D.C..

Brooks, B, P.1988. Application Guidelinesfor Check thlves in Nuclear Power Plants. NP-5479, Electric AEODIC602. C. Hsu. August 1986. Operational Power Research Institute, Palo Alto, CA. Erpenence involving Turbine Overspeed Trip . U.S.

Nuclear Regulatory Cominission, Washington, D.C..

Casada, D. A.1989. Aari!iary Fredwater System Aging Study tblume 1. Operating Erperier.ce and Current AEODIC601 E.J. Brown. December 1986. A Review Afonitoring Practaces. NUREGICR 5404. U.S. Nuclear of Afotor-Operated thlve Performance. U.S. Nuclear Regulatory Commission, Washington, D.C.. Regulatory Commision, Washington, D.C..

Gregg, R. E., and R. E. Wright.1988. Appendit Review AEODIE702. E. J. Brown. March 19,1987, AIOl' Fadure Due to flydraulic Lockup From Ettessive Grease for Dominant Generic Contnbutors. DLD-31-88. laaho National Engineering Laboratory, Idaho Falls, Idaho. in Spring Pack. U.S. Nuclear Regulatory Co.nmission, Washington, D.C.

Miraglia, E J. February 17,1988. Resolutmn of Genenc Safety issue 93,

• Steam Binding ofAuriliary Fredwater AEODIT416. January 22,1983. Loss of ESF Auxiliary Pumps" (Generic 11tter 88-03). U.S. Nuclear Feedwater Pump Capabihty at 7tojan on January 22, Regulatory Commission, Washington, D.C.. 1983. U.S. Nuclear Regulatory Commission, Washington, D.C..

Miraglia, E J. August 8,1988. Imtrument Air Supply System Problems Affecting Safety-Related Equipmen. 1nrormation Nctices (Genenc LetterSS.14). U.S. Nuclear Regulatory Commission, Washington, D.C.. IN 82 01. January 22,1982. Auxiliary Feedwater Armp Lockout Resuhim:from IWstinghouse li'.2 Switch Circuit Partlow, J. G, June 28,1989. Safety-Related Afotor- Alodilication. U.S. Nuclear Regulatory Commission, Operated Latve Testing and Surveillance (Genene Letter Washington, D.C..

W.!d). U.S. Nuclear Regulatory Commission, Washington, D.C.. IN 84-32. E. L Jordan. April 18,1984. Auriharv Fcedwater Sparger and Pipe llangar Damage. U.S.

Rothberg, O. June 1988. Thermal Overload Protectmn Nuclear Regulatory Commission, Eshington, D.C..

for Electric Afotors on Safety-Relased Alotor-Operated ihives - Generic issue ((.E61. NUREG-12%. U.S. IN 84% August 17,1984. Undetected Unavailabuhty of Nuclear Regulatory Commission, Washington, D.C.. the Turbinc. Driven Auriliary Fecdwater Train. U.S.

Nuclear Regulatory Comrnission, Washington, D.C.

Travis, R., and J. Taylor,1989. Development of Guidancefor Generic, Functionally Oriented PRA-Based 1N 87-34. C. E. Rossi. July 24,1987. Single Fadures in Team inspectionsfor BlVit Plants Idenajicatum of ResL- Auriliary Feedwater Systems, U.S. Nuclear Regulatory important Systems, Components and fluman Acnons. Commissina, Washington, D.C..

TLR-AJS74?rG A Brookhaven National Labontory, Upton, New York.

6.1 NU REG!CR.5827

References IN 87-53. C. E. Roui. October 20,1987. Autillary inspection Report Fredwater 1%rnp 1 rips Resukingfrom Low Suction Pres-aure. U.S. Nuclear Regulatory Commission, iR 50-489/89-11;50-499/89-11. May 26,1989. South

\%shington, D.C.. Thras Project inspection Report. U.S. Nuclear Regulatory Commission, Washington, D.C..

IN 884N. C. ii. Rossi. March IS,1988. Reduced Rehabihty of Ste am-Dnven Auttliary firdwater 1%mps NUllEG Report Caused luy Instabihty of iG sodward PG-PL lipe Gorcrnors. U.S. Nuclear Regulatory Commission, NUREG-1154.1985. Loss of Main and Auxilic'y

\%shington, D.C.. li edwater Event at the Davis Besse Plant on June 9,1985.

U.S. Nuclear Regulatory Commission, \Wshington, IN S900. R. A. Atua. August 16,19S9. Robinson I! nit 2 Inadequate NPSil ofAnruimy li edwater hun;>s. Also, Event Noti 6 cation 16375, August 22,1989. U.S.

Nuclear Regulatory Commission, \Wshington, D.C..

N U REGiCR-5827 6.2

Distrihtition No. cf Ne of Copies Coph R.Trasis OFFSr1E Ilrookhaven National 1;iboratory U.S. Nuclear Reculatory Commission Bldg.130 Upton,NY 11973 B. K. G rimes J. Bicicel OWFN 9 A2 EG&G Idaho, Inc.

E Congel P.O. Ilox 1625 Idaho Falls,ID 83415 OWFN 10 E4 Dr. D. R, Edwards A. El llassioni Professo:"r Nuclear Engineering OWFN 10 A2 University of Missouri- Rolla Rolla, MO 65401 W. T. R u.ssell OWFN 12 E23 ONSrrE K. Campe 26 Pacific Northwest laboratory OWFN 1 A2 10 J. Chung S. R. Doctor OWFN 10 A2 L R. Dodd B. E Gore (10) 2 It Thomas N. E Moffitt (5)

OWFN 12 H26 IL D. Saipp E A. Simonen U.S Nuc' ear Regulatory Commission - Recion 2 T V. Yo Publishing Ceordination S. D. Ebneter Technical Report File (5)

A. E Gibson K. D. Landis L A. Reyes 4 Ogitawba Resident Insmetor Office J. H. Taylor Brookhaven National Laboratory illdg.130 Upton.NY 11973 Dist r.1 NURl!G/CR 5F'.7

u.s. Nuca AR Recut ATORv cOwitsiON t. gi,NgE,a NRg,o.usas ** - % a==a neac,usm uc2' BIBLIOGRAPHIC D ATA SHEET c,em.,~c,...on,,mr., NUREG/CR-5827 PNL-7726

.mu Ano saTiTu Auxiliary Feedwater System Risk-Based Inspection Guide for 3. D ATE REPORT PUstiSHED the Catawba Nuclear Power Plant wo .,

j ...a September 1992

4. f IN OR GR AN T.NUVSE R L1310

6. TYPE OF REPOR T (AUTHOR (s)

N. E. Mof fitt, B. F. Gore, T . V. Vo Technical

7. PE RIGO COVERED #aca ane v Oeress 1985-1990

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3. PE R F OhMING O RG ANIZATION - N AM E AND ADDR ESS (n mac. ,- _ -- c neue e.g n nanit anew.a,I Pacific Northwest Laboratory Richland, WA 99352 g, $PONSORING ORG ANiZATION - NAME AND ACOR ESS ist mac rvae %me es eso.e . ,# emeer, waar mac o===a. orfa er Aeven. us asvevete mesinow,y c j and audiar eder**U l Division of Radiation Protection and Emergency Preparedness t Office of Nuclear Reactor Regelation U. S. Nuclear Regulatory Commission Washington, DC 20555

10. SUPPLEME NTARY NOTES 11, ASST R ACT (200 -o se er aus in a study sponsored by the U.S. Nuclear Regulatory Commission (NRC), Pacific Northwest Laboratory has developed and applied a methodology for deriving plant-st 'cific risk-based inspection guidance for the auxiliary feedwater ( AFW) system at pr .surizeu water reactors that have net undergnne probabi'istic risk assessmpnt R,, A) . This methodology uses existing PRA results and plant operating experience information. Existing PRA-based inspection guidance information recently developed for the NRC for various plants was used to identify generic component failure modes.

This information was then combined with plant-specific and industry-wide component information and failure data to identify failure modes and failure mechanisms for the AFW system at the selected plants. Catawba was selected as one of a series of '

plants for study. The product of this effort is a prioritized listing of AFW failures which have occurred at the plant and at other PWRs. This listing is intended for use by NRC inspectors in the preparation of inspection plans addressing AFW risk-important components at the Catawba plant.

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