ML20207A636

Partially Deleted Commission Paper Elevating to Commission Recommendation by Ofc of Inspector & Auditor That Commission Direct Ofc of Investigations to Reopen Investigation of Util Reporting of Thimble Tube Incident to NRC Via LER

ML20207A636
Person / Time
Site:	Sequoyah
Issue date:	10/01/1987
From:	Connelly S NRC OFFICE OF INSPECTOR & AUDITOR (OIA)
To:
Shared Package
ML20205Q426	List: ML20205Q423 ML20205Q468 ML20207A636
References
FOIA-88-228, TASK-PINV, TASK-SE SECY-87-246, NUDOCS 8711100438
Download: ML20207A636 (25)

Text

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s POLICY ISSUE (Notation Vote)

October 1, 1987_

SECY-87-246 l

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l For:

The Comission i

Frun:

Sharon R. Connelly, Director i

Office of Inspector and Auditor

Subject:

OFFICE OF INSPECTOR AND AUDITOR (0!A) REPORT ENTITLED "REVIEW OF NRC'S ACTIONS RELATED TO THE THIM8LE TUBE i

INCIDENT AT TVA'S SEQUOYAH FACILITY' j

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Purpose:

To elevate to the Comission for resolution a recomendatien contained iii the subject report. The recomendation ' relates l

to reopaning the investigatinn by the Office of l

Investigations (01) of the Tennessee Valley Authority's (TVA) reportind of the thimble tube incident to NRC in a i

licensee event report (LER).

This paper also pror' des the Comission with OIA's evaluation of comer.ts by the Executive Director for Operations (EDO) and '0! on the i

subject report.

l Suma ry:

On July 16, 1987, O!A issued a report to the Comission, i

entitled ' Review of NRC's Actions Related to the Thimble Tube Incident at TYA's Sequoyah Facility.' The report was prepared in response to concerns raised by Congressman John Dingell regarding NRC's regulatory oversight of TVA.

The report contained 11 recomendations of which ton were addressed to the EDO and one to 01. The ED0's response (see

! ) agreed with nine of the ten reconnendations in i

the report addressed to him.

The EDO disagreed with Recomendation 2.

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j The ED0's response was silent on whether its views had changed regarding the adequacy of the LER.

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Because no further work is plar.ned by the staff rdfrg i

the adeq of the L OIA has concluded that

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t Discussion:

On March 2,1987, we provided a draf t of our audit report entitled, "Review of NRC's Actions Related to the Thimble Tube Incident at TYA's Sequoyah Facility" to the EDO and 01 l

for connent.

The EDO provided coenents on.May T. 1987; j

however, these corcents were resch.ded on Joly 2,1987, following a series of discussions between EDO and OIA staff i

regarding the coninents, the EDO agreed to provide a revised l

respon d at a later date. Because of the delay in receiving l

the EDO coments and because we did not want to further delay the issuance of this repcrt, the report was issued on July 16, 1987, without EDO connents. O! responded to our request for coctents on March 31, 1987, by stating that the O! staff most knowledgeable of the incident were involved in a priority assignment, and consequently, they were unable M i

l coninent on the draft report within the 30 days we provided.

Following issuance of our report to the Comission. *A I

received responses from both the EDO and 01. A complete i

j evaluation of the EDO consents is attached to this paper (seeAttachment4).

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ED0 Response

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The E00 connitted to implement nir4 of the ' ten recomendations that were applicable to the staff.

Because i

the programs, 411cies, or procedures that the EDO identified in :11s response inve not been fully implemented, we will follow up each of the nine reconnendations during fiscal year 1988 to deterinine if they have been satisfac-torily implemented.

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Accordin to the EDO res onse to the 0!A report..,the. staff has. M ' N.;

et but Mt will be istuing a policy statement a W,df toplemented th s as to provide guidance.in this 'arean',. A WU." ' y i L.,.. 2 ;..!.' ? J A M.. p'f._,'n-the Inspection Manua c' t n.- f ' ,.' j c;,, Ii -

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l 6 ' '"S i l i I 1 i d l t 1 Our concerns regarding the LER.nd the O! investigation follow. c LER Deficiency u ) i i i = 1 1 4 - s / l 7 V v s. I The TVA line organization's September Ib,1984, response to the NSRS finding was that the LER was not misleading and complied with 10 CFR 50.73. They felt'the true nature of the leak was adequately described, and did not consider inadequate procedures or failure to adhere to procedures as causes of the incident. ~. '2 s t, . : (:;?t,. .. ~. v. .'.',^h'm.b' : *,.,...' 4 ','

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) ; 1 i 1 i 1 I I i i i i t 4 i I i I l l i j c' i 6 ') j 1 i i l l I I i t l I i i I i l I p l { l 1 i i i 1%( i i n the folicwing sect ons o s paper.swe ave ~ ~ three issues relating to the incident. the ~ applicable regulatory requirement, the LER description, and CIA's evaluation. The three issues are: 1 . s', 5 q 's g n es b e

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Cause of the Incident; Corrective Actions; and Description of the Event. 1. Cause of the Incident Regulatory requirements: 10CFR50.73(b)(2)(ii)(0). ...(thenarrativedescription must include...) the cause of each coreponent or system ,i failure or personnel error, if known." f. 10 CFft 50.73 (b)(2)(ti)(J)(2)(ii). ...(foreachpersonnel error, the licensee shall discuss) whether the error was I contrary to an approved procedure, was a direct result of an error in an approved procedure, or was associated with an activity or task that was not covered by an approved I procedure.' i LER description: O!A evaluation: O v i 4

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i l l i 1 \\ ~ 2. Correc i Regulatory requirement; j i 10CFR50.73(b)(4). '(the LER shall contain) a description j l of any corrective actions planned as a result of the event. including those to reduce the probability of similar ev.ents occurring in the future." .LER description: J I The LER section ' Corrective Actions,' stated that all ) short-tenn corrective actions were going to be implemented j in the imediate response to the incident, including the recovery of the thimble, and in revihwing possibl'e failure I l modes for the inechanical fittings. For long-ters corrective action, the LER further stated that management had made the decision that future thimble tube c Id not be rfonned duri r operations. OIA evaluation: /vp - 1 i

i m 14 In r l ~ s y 4- [ l i t s i ) s l j i i j f i i i l Description of the Event Regulatory requirement: 10 CFR 50.73 (b)(2)(1). "(The Licensee Event Report shall contain) a clear, spuific narrative description of what occurred so that knowledgeable readers conversant with the design of conarcial nuclear power plants, but not familiar with the details of a particular plant, can understand the complete event."

~ 8-4 r N ~ ', s, t ? e s e r.. Description of the Event Regulatory requirement: 10CFR50.73(b)(2)(1). "(TheLicenseeEventR.,.ortshall contain) a clear, specific narrative description of what occurred so that knowledgeable readers conversant with the design of comercial nuclear power plants, but not familiar with the details of a particular plant, can understand the cos:plete event." l

tru v LER description The LER section, "The Event," stated the following: At the time of the incident, the plant was at 30% reactor power, and the charging flow was increased by 45 gallon per minute (gpm) from 85 gpa to 130 gpm; Estimates showed that the reactor coolant system leakage was less than 45 gpm; "Water was noticed on the seal table" by personnel who were cleaning incore detector t!.imble tubes at the time the leak began; and "The work crew inmediately evacuated the area." OIA evaluation: ~ 5 l (:h ' 3

IA i Other regulatory considerations: i i OIA reviewed the applicable regulations for material false I statements (MFS) in the course of our evaluation of this j LER. OIA learned that the Enforcerent Staff is currently j finalizing regulations which further clarify the existing requirements (10 CFR 2, Part C Supplement VII). The existing regulations applicable to MFS state the following: I In essence, a Material False Statement is a statement that is false by omission or comission and is relevant to the regulatory process. ...in determining the i specific severity level of a violation involving I material false statements or falsification of records, i l consideration will be given to such factors as the l position of the person involved in the violation (e.g., l i i first line supervisor or senior manager), the j significance of the infonnation involved, and the l intent of the violator (i.e., ne011gence not amoynting i i to careless disregard, careless disregard, or i j deliberateness). The relative weight given to each of these factors in arriving at the appropriate severity i level will be dependent on the circumstances of the l violation, e f I 1 l l I '5

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i i ) Recorr.enda tion:_ Note: $? ' f l' nd Sharon R. Connelly, Director Office of Inspector and Auditor l i Attachtnents. j 1, Memo to Chrm. Zech fm YStello i dtd 8/12/87 l 2. Herno to 5Connelly frm BHayes j dtd 8/10/87 3. Meino to JNGrace, Re ion 11 fra f BHayes dtd.3/15/8 i 4. OlA Evaluation of EDO Corwents i i 5. L.icensee Event Report l l \\ Commissioners' comments or consent should 'se provided directly I to the office of the Secretary by c.o.b. 'Aonday, October 19, t 1987. j Commission Staff office comments, if any, should be submitted f to the Commissioners NLT Tuesday, October 13, 1987_, with an information copy to the OTfice of the Secretary. If the paper l is of such a nature that it requires additional time for analytical review and comment, the Commissioners and the Secretariat should i j be apprised of when commenta may be expected. DISTRIBUTION: Commissioners OGC (H Stroot) OI OIA l' [U GPA roo OGC (MNDB) SECY j 6

l. ....v .. ME N latt O!:st. soec. Dass:.. ., g. M MY 34 V.O May 18. 1984 i U.S. Nuclea r Regula tory Cor.::ission Document Control Desk Vashington DC 20$$$ i Centlement t TENNESSEE VALLEY AL*THORITY - SEQt'0YAH NUCLEAA PLANT UNIT 1 - DOCKET NO. ! $0-327 - TACILITY OPERATING LICENSE DPR REPORTABLE OCCURM.SCE RIPC ' SQRO-50-32 7/ 84030 The enclosed licensee event report provides details concerning ejectior one incore detector thichle tube. This event is reported in accordance i with 10 CTR $0.73. paragraph a.2.1 and a.2.tv. Ve ry truly yours. TENNESSEE VALLEY AL'THORITY O. A v) > ~ C. C. Mason I Power Plant Superintendent I Enclosure cc (Enclosure): I i bees P. O'Reilly. Director l U.S. Nuclear Regulatory Cocrzission Suite 2900 101 Marietta Street. NV Atlanta. Georgia 30303 i Records Center Institute of Nuclear Power Operations suite 1500 1100 circle 75 Parkway Atlanta. Coorgia 30339 NRC Inspector. NUC PR. Segwyah ATTACHMENT 5 EXHIBIT (4)N 1 Pai Aa Eew 0: e%% tmeie,c Page I

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1...-....-,. p t ,..c......_-. On 04/19/64. unit 1 wee in mode 1 (2235 peig. 558 degrees r) et 301 reactor power with saintenance personnel cleaning intore detector thtable tubes. A high pressure connection on the thimble tube et tha seel table f ailed resulting in a reactor I toolent systen pressure Wundary leek of approximately 25 35 sps and ejection of one intore detector thisble tube et 2100 CST. i I i i t 1 1 i I EXHIBIT ((.) 3 Pages Pase A d \\ i s

2. t t ( '. ) !..' E f t r a '.;* a i t s 9 ( p...., g. '., ~ '~ r IL%u?i t' .E.t h 3.g lg l r t g e 3 y, y h ,, ). p. p. p ' g. p se-.,....r.......,.......... Back tre et 1 ' * -- s t l e '. t a f : M to tvent The Re at t or Enr tr.o ::.; rr.it (p.tr) had subs.itted various e.aintanance requvatn (n. during late 1H3 v.er.<ver a t. lysed intore detector tnieble tube was encountered. In December 1983. REV suhitted an HR requesting all unit 1 thirble tubee be c16an.4 (MK Act&O::). tw tr.sare.t r. time rettract s=r.s. and lo. prserity, only 9 thar. ele tubes were cleaned daring the unit 1 refueling outage. Prior to startur' f c11 ova n; tt.. outage. KEV f uncttonally tested the intore detector syntes (A;ril 11-13) and identtitat 23 thir.ble tubes which were blocked. Research van done by pit' t o obt ain inf oruation on the possibility of. cleaning the tubes at temperature and pressure. It was deterr. inst that both Trojan Nuclear Plant and leaver Valley Nuclear Plant had cleaned thimble tubes at reactor power operation with no problers being encountered. Vestinghouse representatives were consulted, and they raised no objection to cleaning the tubes at pressure. To11oving canagement discussicas. a decision was made to proceed with startup operations while cleaning the tubes in a stellar technique as Trojan had used. This method would require removal of the 10 path selector and directly attaching a hand trank assembly which inserts a brush into the tube. Unit 1 entered mode 1 on 06/18/84 at 1118 CST and reached 30: reactor power on 04/18/8; at 1700 C57 with thichle tube cleaning in progress. I,5 e !v ey,,t, On 04/19/S4 af ter cleaning five thimble tubes. the job foreman was unsure if the brush was betag inserted completely to the end of the tubes. ' A decision was made to insert the brush into an usblocked tube to obtain information on brush travel in a clean tube. The cleaning assembly was installed at tube EH12 and was inserted to approx-instely 15 feet prior to shift change. The second sht!t cleaning crew took over and began inserting the brush. Each turn of the cleaning tool crank resulted in inserting the brush 10 inches further into the tuh. Personnel stopped at the fif tieth (50th) crank to ensure the ow.ber of turns had bee, properly counted. At the seventy-eighth (78th) turn, the tool handler noted that scia pressure was being required to turn the crank. At approximately 2100 CST during the seventy-ninth (79th) turn (brush would be approsimately 80.8 feet into the tube) water was noticed on the seal table. The verb crev incediately evacuated the area. Af ter exiting f rom the personnel containment airlock the fore an requested the public safety officer stationed outside the airlock j te notify the shif t engineer (5t) of the situation. Since the public safety officer was unable to reach the St by phone, the foreman proceeded directly to the control roce following removal of his anti-C clothing. At 2110 CST. the pressuriser 1,evel was decreasing and the charging flow was increased by 45 spe (f rom 35 sps to 130 spa). At 2116 CST, the pressutiner level decrease stopped and began to increase, indicating the reactor coolant systeli (RC5) leakage was less than 45 spe. Later estimates showed the leakage was approximately 30 spa. At 2117 CST Power reduction at 11 per minute was initiated. At 2120 CST. Radiological taergency Plan Procedure IP-2. "RCS 1.eakage Creater than 10 spo Identified." was inittsted, and the Operati:ns Supervisor and Assistant Plant Superintendent-Operations and Engineerin; vere nettfled. At 2121 CST vith reactor power at 15:. (525 degrees r and :: ) s;;). t he T'.*A c.t y s t e t t a'.a s t wa s ne t t t t e d. EXHIBIT (4) S Pasen Pase J of

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At 21): C 5;. 1:.. ...: $ar 1* CTU te 10 CTF. $0.7'.a.1 1 (initiatien : f IIri.?.:and ec p$retur,. at A / t r.rtified of tia 5vtts rursuant At *:05 C57. RCS rrt **ure e r.us d v.). d to ecce $ vas 1900 psig and 300 degrees T respectively, and a contro 50 *2.b.1 1. A f r l:s: r af. area radiation r-r.itrr. a rarticulate radiatien eenitor,itters, and six non-gu 1ettru ents tr. progress. transsitters, tvr treasuriser pressure transef ailed apparen A containeest due to the envitor. ent. found increrable. d tal and,not transmitter was alstransmitter has been detercined as coinc to leceverr Inforvation and tvents leadint d depressuritation of the *C5 was ate was estir.ated At 0932 CST on 04/20/84, unit 1 entered sede 5 anAt 1114 inittsted. At 1400 CST vith RC5 pressure at at 18 sps. at 5.4 psig. l vater level had been levered to At approxisately C'1) C5* on 0./01/8.. the vesse::; a f the s e al t s>1s t o a t Later !:r.:. tse r blaniet in the pressur;ter. as lost frot the RCs vculd be due to cr.e pressure of tr.e attreten cavecalc about 70; feet. t during the, event. l table area to observe h At approminately Ot00 Cst, four personnel entered t e seaPersonnel r A saali, hroughout the room. the general condition of the area. completely ejected from the guide tube and twisted ttube at the seat ta d steady stream of water was flowing from the gui ethe nitrogen blan Radiation surveys l table area. 200-300 res at it indicated levels of 2 3 res at the entrance to the sea d greater than 1000 res in the center of of the pressure fro the radiation reading of a smear taken f rom the flo i and of the tube closest to the seal table, an Personnel reported the tosperature and humidity in th the ejected tube, very high maktes working canditions dif ficult. tillites per hour. All four ly two minutes. area, but only recained in the area for approximate 036 rem with a maxim individuals received a total cocbined dose of 3 exposure of 1.219 reo. d a second entry into the two individuals ma e The two approximately 1800 CST on 04/21/84 phe of the area. seat table area to take additional, dotatied photog n minutes and received dos At l The photographs that were taken duri of 1.966 res and 1.939 res. r ctice the removal technigues. betsee an extressly valuable asset. process which includ EXHIBIT (rA r.e. _L d.8 P < i - r 1

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Ie it 'r e. ) *. ! 7 it la l-O te-s..-...........,....-s.o. t:. celli,le ar.4 apir. en 04/ /f4 th< folic ing eight alternatives f et rt eval cf L:.. e,'arted tute vere 417:U~saed 1. The t'.1-tie tute ceuld be f ed inte ths incert detecter storsg. locat t;r. ing s te :: g polar crane wall. This method would reduce radiation exposures due to the close accessibility of the sterage location. But disadvant:ge> su:h as possible inter. f oren:e with intore prehes in storage, unincw. interf orsnces while insertsmg the tube into the storage location, f uture disposal 'ef the tube. and whether the polar trant wall vould provide adeguate shielding were also pointed out. 2. The thimble tube could be seinserted into the guide tube. This vould allow disposing of the tube by nocal seans during the nas.t re'f ueltas outage (removal via the vessel). but would also cause loss of one incore detector location for the nemt cycle. Other disadvantages included unknown difficulties in starting the tube in the guide tube and problems caused by kinks and sharp bends in the ejected tube. 3. The tube tow 14 be moved into the keyvay by inserting the tube through the seal table drain or spares. A shielded pipe could be installed in the keysa) to store the tube. but additional radiation axpesure vould be obtained to f abricate ths sterage yi;in; in the Leyvay. Additi:nal di!!1culties included unir.rer. hanger interference during transf er and proble:s with later access to kerway. 4 The thisble tube could be.wt into pieces and stored in a pig.. Using video monitors. long. handled tools would be operated free behind shielding to cut the tube and drop the pieces into a funnel-pipe arrangement which would transf er the pieces into a shielded pig in the raceway. This method would reduce personnel exposure and simplify disposal since disposal could be planned at a later date. This method could also be easily mocked up at Vatts &ar Nuclear Plant for stou-lated practice. Disadvantages such as the required weight of the pit. un.'oreseen f problems with the funnel-pipe transf er assembly, and unforeseen probless with cutting tools were pointed out. S. The thinble tube could be wound onto a spool in a water essk. This sethod could also be easily mocked-up at Vatts lat. but difficulty of connecting the tube to the spool keeping the tube stangled as it vis turned onto the spool, and the sis, j and weight of the task were pointed out as disadvantages, i L. The thimble tube c~ourd be pulled through a PVC pipe free the seal table to the refuel floor. This method was mansioned and immediately withdrawn as impractical. 1. Use of a mechanical robot to perform the work. This would greatly reduce personne: axposure and could be used in conjection with one of the other methods. Disadvantages pointed out were the size and weight of the robot and unknovn dif ficulties in set up. 3. An outside contractor could be hired to resove the tube. This nethod veuld reduce exprsure :: plant pe r sov.#1. but the reductaer. in plar.1 r.a?.3;4 tr.t t.'?.t r : *. of the vars v:..: ?. t as accepta:14. EXHIBIT (4 ) page 5" d.A ! ss

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r, ; e Y-A'?.'G* ap l,.,,, c. e .. ;.a l .o. .,. rn [ !...'. c.'t r.; di s c us s t en o f t ht s a e i pl.1 atc 4 t.3?.&; t r. s r.1 c e r.t !.3 6. to usc opticti 4 &*:v.. On 0.!:)/64 the cenditten of the tutin; tr. tLi ava; ta!.le area sas e. :'.<d. at Va t t s br usinr the det ailec rictures c.'ta f ra.' csr.n. the escond satrv et s-t. * ;.h. A veri tea *. then sinslatid the actions 1:ss;. vi d t t i.l s durin the set a* vsti at Seguoyah. In conjunction with the practics sesstor.s at Watts ler shielding v:e betn; installed at Sequeyah, fello.ing difficulties encountered duttnp the practice ressions and uposur. lesels be tri received f roc shielding installation, r.anagercal reevaluated the optiens on 0&!!4/f4 and cencluded to use a combination of options 4 and 7 above. The pcrtion of the tube with the highest radiation level (approximate 1) 20 feet) would be cut free and dragged into the racevay.' Once in the raceway. the vori of cutting this section into smaller pieces and placing the pieces in the pig could be performed by the robot. The lover radiation levels of the remainder of the tube vould allow personnel to cut it up and dispose of it. A work team then slowlated these actions s>n tt, Vatts lar soci up. To11oving the practice session, additional meetings were told to finalige the plans of the operation. The plan was as follows: 1. On the first entry. one individual vould enter and cut tne tube near a designated peint an6 1 nadiately exit., Or. the secons entry. two individuals vou'1d ther. entar ana coordtr.ats attacatn; a cable to the section of tubing using a special clarp. 3. Another individual stationed in the raceway would then pull the section of the tube into the raceway uains the cable attached in step 2 above. Using this plan. the 20-fc>ot section of the tube with the highest radiation levels was successfully transferred into the raceway on 04/25/8t with no problaas being encoun-tered and only 100 nr u posure. Personnel thtn entered the seal table area and cut the resetning portion of the tube into smaller rieces. The tube was cospletely re.oved from the seal table area by 1900 CST on 04/23/84 at.d actions to decontaminate the sesi table area were initiated. During the activ1'ty of decontactastion and retsving the recaining section tree the seal table area.1 can-ron of total exposure eccurred. The lov radiatica level sect 13n of the tube was delivered to the vaste packaging area and prepared for shipsent to an offsite burial facility. A new thimble tube was installed in the D-12 guide tube on 04/28/84 with no problems encountered.. Cleaning of the twa.aining thimble tubes was contracted to NUS who started the cleaning operation n 04/26/84 and cospleted on 04/30/84 with so problems encountered. Of the tastrv-mentation which f ailed, the area radiation senttor was replaced and all other instru. (sentationrepairedand/orrecalibrated. EXHlBIT (G) 8 6 4 Nm i pp

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5. r- +:.- l s t s. s i t ' t.* i. o, u.v..irst ) ' t '.-: s. ._ s. :.. eo* y An evaluatten of a: 1 Clas, it equipsent in the incere instrutent rsos vai ca.:. in deter. ins !! the envirer.rer.tc) cenditione er.; crier.:cd during this ever.t coald ti dstrittnta to thsit rrssent qualifies life. T!.s evaluation descr tr.et tr.at f..- deterioration of quali!1ed life was experienced based on temperature and radiation readings duttn; and after th( event. on 04/26/84, the robot was lovered into the racevay for a e6cck ur test of th< actual cutting operation. The robot would lift the tube and carry it to a table with two hydraulic cutters. Using video camera's, personnel vould remotely operate the cutter when the robot had the tube in place. The robot would then carry the smaller (cut of f) p,ece and place it in the storage cask. When all of the tube had been cut and placed in the cask, the robot would fill the remainder of the cask with lese shot and close the task. The actual operation was started on 04/27/44 an(, completed on 06/28/84 An approntaate sia-foot section of the tube was found'to have a low radiation level and sent to vaste packaging to be added to the other low level tubing f or shipping. tvaluatten of the Cause of Failure Tive possible cedes of f ailurs cf the fitting vere' identified anc evaluated. Evaluatto: of eser, possible f ailure was accocplished by inspection of tne f ailed part and tests perforced on a sock-up of the cleaning tool and seal table asse=bly. The possible failures and their dispositions are as follows: 1. 1sproper assembly of fitting (such as ferrule upside down or in wrong order). The ferrule and tubing were inspected and assembly found correct. 1. laptoper expansion of the end of the tube. Inspection and comparison of the sock-up specimens to the ejected tube indicate the tube end was properly expanded prior to ejection of the tube. Crack 1r.s of Terrule Although the f errule was found cracked circumferentially approxit.ately 180' on the inside diameter, the relative motion by the ejected tube and fitting would have caused the crack to close if it existed prior to the event. 4 Nut not tightened or had become loosened f roe other operations. The nut was fom 4 tight following the event. Destructive tene.le tests performed on similar fittf.4s confimd that the nut remained tight. 5. The fitting being a ecchination of Cyrolok and Svagelok parts. 5.rseguent evaluatten and discussicas vi:5 venders has iste-.inet that this ut.f t;. ratter. vauld n:t have causec the f ailure. EXHlBIT (4) Pese 'I d Psee 1

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n.. 72F f. a... e :.. t r. ; t t e! r. i .e. e f .... ~..... ,s. 6. Cleanin; fixtars ir.resed ur.usu:! f eir ce # rn the asscelly. This a;;s ers tr t, the r.a s t prebabls cases of ths fa.1.is trc th. t s t s r c r f e rns t e n t r.i .': e -u;. Thre e fittin;s vtis f:lls4 by a 76rs.-i.;st:.af.; cr. the handle ef ths 61 s. :.. r.; f : r t. r e estk-up. i t.s failed sock u; tubst v$rs similar in appearance to ths actual failed tube and fittitsg. Strain raures vere installed on the cort-ur tube a-f a statured lette vae artlied te t.66 r.st'..ur handit. A Flot van t&cs 968t. a;;1ted force versus strain. Tube strains of arrroxt:ately 1000 straan units were n:ted just due te installation of the casantn; tool. Evaluation of the plot she.e: sees slippage at 30 lbs. applied force, some leakage appeared at 160 lbs. force and separatten occurred at 250 lbs. force. Corrective Aettons All short-term corrective action taken has been described in the above text. per sendor recconendations, the seal table and essociated fittings were inspected. ~nts inspection determined that no additional corrective action was required. For long-term corrective action, management has nada the decision that future thittle tube cleaning vill not be performed during power operations. l 1 j EXHIBIT (G) E Pmen tw.A d. i _ _ _ _ _ _ _}}