ML20148P600

Discusses Followup Study Re Degradation of Internal Appurtenances in LWR Piping During Normal Plant Operation & Potential Effects When Degraded Appurtenances Are Subj to Accident Loads.Recommends Review of Recurrent Problems

ML20148P600
Person / Time
Site:	Beaver Valley, Dresden, Kewaunee, Saint Lucie, Arkansas Nuclear, Turkey Point, Crystal River, Duane Arnold, San Onofre, Crane
Issue date:	12/24/1980
From:	Ellen Brown NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
To:	Michelson C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
References
TASK-AE, TASK-E020, TASK-E20 AEOD-E020, AEOD-E20, NUDOCS 8101150319
Download: ML20148P600 (4)

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DEC 2 41980 l

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-12 ftEMORANDUM FOR: LCarlyle Michelson, Director I/

d Office for Analysis and Evaluation of Operational Data FR04:

' Earl J. Brown Office for Analysis and Evaluation of Operational Data

SUBJECT:

INTERilAL APPURTENANCES IN LWR's An AE00 study was recently initiated as a fullow-up to orevious ACRS

, - concerns about degradation of internal appurtenances in LWR piping during nomal plant operation and the potential effects when degraded appurtenances are subject to accident loads. The primary concerns are that accident loads could result in failure of devices already degraded during normal service such that mitigation of the accident would be adversely affected or that continued degradation of these devices during nomal service may in itself lead to an accident. The purpose of this memorandum is to provide a brief background sumary of the initial ACRS inquiry and identify additional events where appurtenances were degraded during nomal operation so that the infomation will be available to the responsible program office as appropriate.

BACKGROUt'0 The initial. inquiry was raised in your letter dated June 13,1979(See enclosure 1) to ACRS members. The subject was failure of a.feedwater flow straightener as San Onofre Unit 1 as reported in LER 73-013. NRR staff subsequently discussed this with ACRS as part of the general subject of seismic or blowdown capability of small components within the reactor l

coolant systen. A specific.NRR staff response to the ACRS on the San Onofre LER 79-013 was to have been handled by letter after the meeting, but there is apparently no documentation of a response.

1 EVENTS ASSOCIATED WTTH INTERNAL APPURTENAMCES A.

San Onofre, Unit 1 1

SeveraleOentsinholvingfeedwaterflowstraightenershaveoccurred.

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the sequence and actions were:

LER 78-009, August 1978 - The flow straightener in loop "B" feedwater line dislodged from its cornal location and became lodged against the downstream orifice plate. The straighteners in loops "B" and "A" eere recoved and replaced.

'LER 73-013,. Movember 1973.

The ficw straightener.in loop. "C",fgepyater, line dislodged from its normal: location and became lodced' aaainst the

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• This was the LER that promp ad the ACRS auestions.

THIS DOCUMENT CONTAINS l

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downstream orifice plate. A new stratghtener was ordered and was to be installed at the next cold shutdowri of sufficient duration.

(See i

enclosure 2)

LER 79-002, April 1979 - The flow straightener in loop "B" feedwater line dislodged (2nd time) from *ts normal locations and became lodged against the d4wnstream orifice plate. Straighteners in loops "B" (2nd time) and "C" were replaced.

LER-80-004, January (1980 - Segments of the flow straightener in loop 3rd tim "3" were dislodged pl a te. The 1000 "B" flow straightener was replaced (3rd time) but the replacement was fabricated from stainless steel rather than the original carbon steel. The flow straighteners in loops "A" and "C" were scheduled for modification during the April 1980 refueling outage.

(See enclosure 3)

D, Takahama 1 and Ikata 1 It was reported on May 26,1980 (enclosure 4) that cracking of flow straightening vanes on the inlet side of primary coolant pump piping had been discovered on Takahama 1 (a PWR supplied by Westinghouse) and Ikata 1 (a PWR supplied by Mitsubishi Heavy Industries). They plan to remove the T10w straighteners.

C.

Dresden 3 LER 77-021. June,1977; LER 78-005, March 1978; LER 78-037, September 1978; and LER 79-032, November 1979 report leaks in the reactor feed pump mini flow line in the vicinity of a restricting nrifice. The problem had occurred at Dresden 2 and 3 since 1972 which led to sections of pipe being replaced in 1975 and these replacemdnt pipes are those that began leaking in 1977 as reported by these four LERs.

D.

Dresden 2,1972 A main steamline flow restrictor failed on September 7.1972 and became lodged in the inboard main steam isolation valve.

Failure was caused by vibration induced fatigue.

E.

Turkey point

4. Anril 1980 LER 80-005 reports that auxiliary feedwater pump " A" failed to deliver the required Now rate during performance of inservice testing. The cat was thought to be either control circuit calibration and/or a flow restriction in the pump discharge valve.

F.

Beaver Valley.1I 1979 LER 79-36 reports that the LHSI oump failed to develop required recircu-l ation flow. Pieces of a 11/2 incheplastic fire hose nozzle were discovered in the recirculation check valve.

OFFICE h SURNAMEk...

DATEk.

NQC FORM 318 (9-16) NRCM 0240 DU.S.-3OVERNMENT PRINTING OFFICE: 1979 289 369 m

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Duane Arnold, 1979 LEp 79-005 reports that both emergency service water systems were inoperable.because of plugged water strainers. Apparent cause is improper design application.

H.

Crystal River, February 1978 LER 78-017 reports that loose parts from the Burnable Poison Rod Assembly damaged a steam generator above the tube sheet. Debris was found in both the upper and lower head of the once through steam generator, I.

St. Lucie Aoril 1978 Some incore instrument t5imbles separated from the upper guida structure.

-J.

Three ' tile Island 1, March 1976, and Arkansas Nuclear One, Unit 1. March 1975 Surveillance Specimen holder tubes have damaged and missing parts as a result of flow in:iuced vibration.

K.

Chooz Sena & Tein Vercellese. Mid 1976 Steam generator tube sheet was damaged by parts broken loose in the reactor

. pressure vessel.

L.

Xewaunee 1, 1975 During startup, all auxiliary feedwater pumps exhibited reduced flow resulting from resin beads pluggimg the strainte to each pump.

Fine mesh strainers were removed.

DISCUSSION AND RECOMMENDATIC'ts The events cited in the previous section illustrate that several different types of problems hav'e occurred. Some general problem areas are damage and dislodgement of relatively large devices such as flow straighteners, vanes, and restrictors; cracked piping as s restit of complex flow conditions at flow orifices; some type of debris restricting 71ow through valves and strainerst and objects breaking loose to damage large equipment such as steam generators. Also, some events are essentially repeat occurrences such as the flow straightener problem at San Onofre #1 which has developed twice since the initial ACRS inquiry about LER 78-013 and the Dresden #3 leaking mini flow pipes in the vicinity of restricting orifices.

It should be noted that these examples were gathered from different sources or search techniques and illustrate the occurrence of degradation during normal oper-ation that raises stnut safety questions about potential operation when subjected to wreally more severe loading under accident conditions. Since reporting'of these events may be done under many categories such as instru-xentiti6tr. flow blockage, specific systems, or specific componer,ts, it could be a diffiicult task to develop a comprehensive event list of occurrences of degradation of internal appurtenances.

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NRC FORM 310 (916) NRCM 32 40 DU.3, GOVERNMENT PRINTING OFFICE: 1979 289 369

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.r It is recommended that appropriate program offices should gise consideration to the following:

1.

Review the flow straightener problems and proposed corrections for the events at San Onofre Unit 1.

2.

Initiate a review to identify: a) the use and location of internal appurtenances, b).the design methods, c) load definition for such components, d) the effect of failure with respect to potential for causing an accident or impeding mitigation of an accideot, and e) the occurrence of 9perational problems to date. The review should be relatively troad and include such devices as flow ori-fices, flow restrictors, flow straightening vanes,. thermocouple wells, flow scoops, 61ffusers, and thermal sleeves.

Original Signed by Earl J. Brown,

Earl J. Brown.

Office for Analysis end Evaluation of Operational Data Eoclosures:

1.

Letter dated June 13, 1979 to ACRS discussing feedwater flow straightener.

2.

Letter dated December 20, 1978 and LER 78-013 from San Onofre #1.

3.

Letter dated February 13, 1980 and LER 80-004 from San Onofre #1.

4 Letter reporting straightener vane cracking on Takahana 1 and kata 1.

cc:w/ enclosures:

J. P. Knight, NRR R. J. Bosnak, NRR J. R. Rajan, flRR W. R. Rutherford, IE J. C. McKinley, ACRS Distribution:

Central File u AE00 Reading File dE rown AE00f[,8.

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g' k NilCLI. AH ltl.(illL A l t 'HY COMMISSION

, fj t,k V,Jjlfj ADVisultY COMMi t fl.t ON nl. ACTOR $AFEGUARDS Enclosure l w.mora n. n c. rov.,5

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Jure 13,1979 TO:

ACRS HEMbr.RS

.c FROM:

C. Michelson, ACRS Consultant p///

SUBJECT:

Failure of Feedsater Flow Straightner at San Onofre Nuclear Station, Unit I s

1.ER 78-01'3 for the subject incident brings into focus a related concern which needs to be addressed for all piping systems containing internal appurtenances such as flow straightening devices.

The concern is that such devices might have to be designed to withstand blowdown flow load-ings in addi tion to normal loadings.

Consideration should be given to the possible consequences of an internal appurtenance being dislodged by the blowdown flow Of particular concern would be the' case of a straightening vane which might become lodged in a valve whose closure is an essential mitigating step following an accicent.

'f if such a consequential failure is unacceptable, the supporting attach-ment scheme for the appurtenance must be designed for the blowdown load-ings including the degradation ef fects of cyclic faticuo.

It should also be recognized that blowdown flow nignt be in ei ther direction.

This could af fect the severity of loading for nonsymmetrical arrangements.

When considering the consequential ef fects of an internal 80purtenance failure, consideration should also be given to possible steam generator tube damage.

Of particular concern would be a primary or secondary side piping failure whose blowdown consequences might include the generation of internal debris due to one or more consequential failures.

Inis could lead to multiple steam generator tube fiilures including, perhaps, both steam generators.

The present der. inn basis for PWR plants does not take into account the possibili ty nf sur.h a combined primary / secondary side blowdown into containment or the p.mibility of a blowdown outside of containment if the debris shnuld also prevent i. solation valve closure.

There are a number of internal appurt enances which need to be examined from this viewpoint.

Typi:al exampics are flow of fices, flow eierents,

thermocouple wells, s traghtening vanes, flow scoops, flow tubes,

di f fusers, and thermal s10evns.

Tho plant Sa fety Analys!s Repor dran-ings may not clearly identi fy such appurtenances for revicu.

It mignt be interesting to find out hva t.h i - problem is being handled by the NRC.

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in my opinion, this LER is a good example of the type of safety Question which might be uncovered by a proper examination of plant failures during normal oneration.

Equipment weaknesses revealed during the generally less severe loading conditions of normal oneration could be importar.t indicators of how the equipment and systems might be expected to perform under potentially more severe accident loading conditions during which j

such consequential failures might not be acceptable.

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J.S, Nuclear Rmulatory CanTniccion 7.ejion V Suite 202, Walnut Creek Plata 1Q90 !Jorth California Boulevard lainut Creek, California - 94596 1tention: Mr. R.11. E.ncelken, Director IMcket

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%)-206 On Glof re Unit 1

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In accordance with the repcrting rcquiie:r.cnto of Section 6.9./4( a of

- cendix A to the.Gcn onofre Unit 1 Proviciona! Omrating 1.icence the fol h,+

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' n infat mation and al. tc.ched Licensec Cvoit-Mv>rt are subN t.ted.

'tui, letter

eccribes a reportable occurrence involving the feedwater system, on ikwember 25, 1478, the indicated feedwater flow to "C* steam generator

'nereaced approximat.oly sovent y f tve percent. Actual "C" steam generator

'eedwater flow was determined to be less than the indicated value through oination of steam generator level, steam flow and! other plant parameters.

is a result of the inoperability of one of the three steara/feedwater flow

-ismatch channels, continuous operator surveillance was initiated in, accordance

' ai"Jh Technical Specification 3.5. Table 3.5.1.

The feedwater control to "C" 3:eam generator was maintained on automatic and the level stabilized at the armal value.

Radiographic examination of the "C" feedwater piping indicates that the

' low straightener upstream of the feedwater flow orifice plate dislodged

'~as its normaj location and moved downstream where it lodged against the eifice plate. This resulted in an increase in feedwater flow indication me flow transmitter span was adjusted to return indicated and recorded i

L,tlues of feedwater flow to "C" steam generator to their actual values. This I

is the effect of returning the steam.feedwater mismatch channel to operative

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(C:Z Decacher 10, 1978 Pcga TW By letter dated August 29, 1978, we reported a sim M ar occurrence involvin piping. g the flow straightener in the "B" steam generator' feedwater As indicated in that letter the "B" flow straightener was rernoved and replaced during the recently com,pleted refueling outage. Additionally, the "A loop flow straightener was removed and replaced. The "C" loop flow straightener was not replaced since at that time only two replacement flow straighteners were available from the manufacturer. The " " lcop was, radio-graphed, however, and the flow straightener appested to be securely fas-tened.

A replacessent for the loop "C" flow straightener, along with a spare, has been ordered from the manufacturer and will be installedt at the next told shutdown of sufficient duration. At that time an improved fastening method, such as the' ' cr1 on loops "A" and "B" wf]l be employed

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these modifications will preclude occurrences of this type.

There was no degradation of plant safety during this incident. Two of the three steam /feedwater flow mismatch channels remained fully operational meeting the minimum requirements of Technical Specification Table If you should require additional information concerning this occurrence, please contact me.

Sincoroly, Y ' 'M,,. I /

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FGhruary 13, 1930 U. G. thclear Kcp21 story C.dscica EDgian V suito 202, Italnut Creek Plaza 1990 North Chlifamia Eculevard Ishlaut. Chak, California 94596 Attentiont Mr. R. H. Engelken. Djrector Cocket do. 50-206 San Onofra - tindt 1 Dear Sir This letter constitutes a repcrtab3e occurrence involving the feedwater

gygtes, Submittal is in accordance with the reporting requirements st.pu-lated in Section 6.9.2(b) of Appendix A to the Provisiona3 Operating License OPb l3.

On January 19 invaased approsisa,tely fifteen percent.1960 the indicated fesdwater flow to "B" steam ge Actual "B" steam generator feed-water flow was de+M=4 to be less than the indicated value through ex-andnat. ion of stem generator level, steam flow and other plant parameters.

As a ruaalt of the inaperab.ility of one of the three steam /feedwater flow suissatch' channels, continuous operator surveillance was initiated in accord-ance with Tschedca? Specification 3.5, Table 3.5.1.

The feedwater control to "D* stsam generator was maintained on automatic and the level stabilieed st the ac u al nlue, I

g hadtiegraphic examination of the "B" feedwater pdping indicated that the flow straightener upstream of the feedwater flow crifice pJate was missing segments of various tubes. The tube segments had apparently ledged against the orifice plate causing the increase in feedwater flow indication.

The flow transridtter span was adjusted to return indicated and recorded values of feedwater flow to "B" steam generator to th~eir actual values. This had the i

effect of returning the stwa/feedwater flow mic=ctch channel to operative I

status. Similar incidents involving the flow straighteners at San Onofre I

l were reported in LBt's78-009, 79-013 and 79-002.

g The "B" flow straightener was removed during the January 26,1980 plan.t outage, An examination of the damaged straightener indicatec that the centen steel tubing was experiencing excessive erosion,

V, S, }aaclear tegnalatory hi*eion Page 2 l

A new straightener fabricated from stainlesa steel tubir.g with a modf-fled weld attachment scheme was installed on the "B" loop. The improved erosion resistance and structura3 strength of the stainless steel material should prevent it fran segmenting. The "A" and "C" feedwater flow strai@teners will be similarly modified during the April 1980 refueling outage.

At the time of the feedwater piping dia**M1y, no flow straightener segstats were found near the orifice plate. However, segments were re moved from the flow control valve icested downstream of the orifice and in the lepass repalator. The valves and piping were thcroughly inspected and retummad to service.

There was no degradation of plant safety during this incident. Two of the three stsam/feedwater flow mismatch channe3s reatned fu]Jy operational meeting the nunimum requirements of Tecnical dpecification 3.5, fable 3.5.1.

If you should require additional infomat:fon concerning this occurrence please contact me.

Sir.cerely, O'

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U!K,LL;SlFIED lllCuiltl!iG Deparonent o ' State TELEGRAM i

PAGE 01 TOKYO 09526 0102107 C24i l

ACTION NAC-02 INFO OCT-Cl EA-12 AOS-00 OES-C9 OCE-17 INA-10

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076127 010313C /14 R 300E00Z MAY 80 FM AMEMBASSY TOKYO TO SECSTATE WASHOC 8852 l

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LAFLEUR, IP E. C.

12065: N/A TAGSt TECH, ENAG, JA

SUBJECT:

STA"US OF PERICOIC EXAMINATIONS ON NUCLEA4 POWER PLANTS IN JAPAN 1.

AGENCY OF NATUAAL RESCbRCES & ENERGY (A NR E ),

CN-MAY 26, 1980 ISSUED INTERIM ANNOUNCEMENT OF THE

'J T A T U S OP PERICOIC MAINTENANCE EXAMINAT70NS CN KANSAI EfCO'S TAKAHAMA-1 PwA B26 MwC), CHI-!

1. wA 1,175 E)

ANO SHIKCKU EPCO'S IKATA-1 iP w4 565 MWE) wHICH HAVE BEEN SHUTOOWN FCA INSPECTIONS.

F OL L ow! NG AAF FINDINGS OF ANRE:

A, ON TAKAHAMA-1 AND IKATA-l SUPERSON*C INSPECTIONS ON STRAIGHTENING VANES, LOCAT'iO

.' N S I D E OF THE INLET SIDE OF AAIMAPY COOLANT PUMA

PIPING, INDICATED POSSIBLE CRACKING.

SU AF ACf!

INSPECTIONS CN THE VANES ASVEALEO THERE WERE SEVERAL CRACKS ON THE VANES, ANAE BELIEVES HIGH CYCLE AESONANCE VISAATIONS DEVELOPEO, SY WHI AL ACOL AT THE TIPS OF THE VANES ARE THE CAUSE OF THESE FA~IGUE CRACKINGS.

ANAE INSTAUCTED KANSAI ANO SHI K OK U OPEAATORS TO AEMOVE CAACKEO VANES AS TESTS HAVE VERI *IED THE REACTOAS CAN GO DACr TC NORMAL OACAATION WITHOUT VANES IN THE P I P I NG.

8.

ON CHI-l VISUAL INSPECTICNS CN FUEL AS S E MBL I E S, USING IVB-MEAGEO TELEVISICN CAMERA, AEVEALEO 31 OAMAGEO CCIL SPAINGS PCA AETAINING CONTENTS

'9 U A N A B L E 2CISCNS.

NEUTAON SCUACES. PLUGING OE VI CE S).

VISUAL I N!iF E C T I ON S ON CAAC"EO SUAFACE CF SAAINGS HAVE INO!CATED fiCPE "STRIATICN PATTERNS" wHICH ARE CHAAACTEAIS*IC CF HIGH CYCLE FATIGUE OF MATERIALS.

ANAE INSTAU TED KANSAI TO AE AL ACE ALL OAMAGED SPAINGS WITH NEW CNES, ALTHOUGH ANALYT! CAL TESTS CCNF I A ME O THAT EVEb. w1TH CAMAGEO SAAINGS THERE w!LL BE NO AISK CF LOSS OF CONTENTS FACM FUEL ASSEMBLIES OURING NO A MAL AEACTCA OPERATION.

2.

FURTHER DET AIL S WILL BE CAOLEO TC NRC BY HAYAKAWA OF NS8/STA, MANSFIELO

.