ML20065E375
| ML20065E375 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Hatch |
| Issue date: | 06/29/1979 |
| From: | Boehnert P Advisory Committee on Reactor Safeguards |
| To: | Kerr W Advisory Committee on Reactor Safeguards |
| Shared Package | |
| ML082180533 | List:
|
| References | |
| FOIA-82-261 NUDOCS 8210010095 | |
| Download: ML20065E375 (1) | |
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'o yi, g'g NUCLE AR REGULATORY COMMISSION ADVISORY COMMITTEE ON RE ACTOR SAFEGUARDS 4'
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W ASHINGT oN, D. C. 20S$5 June 29, 1979 W. Kerr, Chairman Hatch Subcommittee FAILURE OF BACKUP CORE COOLItG SYSTDiS AT HATCH UNI 2 BWR Attached is a PNO (Att'achment I) describing an event that occurred at E.
I. Hatch Unit 2 which resulted in the failure of the reactor core isolation cooling (RCIC) and high pressure coolant injection (HPCI) systems following a low water level reactor scram. Core cooling was eventually established by use of the condensate system.
Of particular interest in this event was the system inferaction failure mode of the HPCI system (see Attachment II). We steam supply valve to the HPCI turbine failed to open due to water leaking from the HPCI pump seal cooling water line and entering the valve oil control system. %e water entered the oil system as a result of a closed drain valve beneath the HPCI pump which allowed the water to back up and enter the pmp hous-ing and drain to the oil system.
Additional investigation revealed that the drain valve was not included in cny plant diagrams, nor was it known why it was even installed.
It was also noted that the turbine oil systems lack a water detection systm End this may have generic implications.
Yesterday (June 28) I attended a meeting between the D. Ross Bulletins and Orders Task Force and representatives of BWR utilities. %e above event was discussed and the utilities have been asked to address this item.
Given the above NRC action I recommend no ACRS action on this item at this time.
a ehnert Reactor Engineer Attachments: as stated ec: ACRS Members ACRS Staff ACRS Fellows khO 95 820628
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UDELLB2-261 pop
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- e PRELIMINARY NOTIFICATION June 6, 1979 PRELIMINARY NOTIFICATION OF EVE.NT OR UNUSUAL OCCURRENCE -- FNO-79-1 This preliminary notification constitutes EARLY notice of an event o'f POSSIBLE The information presented is as initially safety or public-interest significance.
received without verification or evaluation and is basically all that is known by IE staff as of this date B;
FACILITT:
Georgia Power Corporation Eatch, Unit No. 2 Docket No. 50-366 Baxley, Georgia
SUBJECT:
FAILURE OF BACKUP CORE COOLING SYSTEMS On June 3, one of two operating feedwater pumps tripped, causing a low water level reactor trip. The Reactor Core Isolation Cool.w (RCIC) turbine started e
The cutobatically as required but isolated due to a rupturse,*xhaust diaphragm.
licensee's investigation revealed an internal problem in tua check valve on the The stud turbine exhaust line, apparently causing a teeporary flow blockage.
fostening the check valve disc to its operating arm bad failed.
Replacement valve internals are enroute to the site and the RCIC will be repaired prior to startup.
The High Pressure Coolant Injection (HPCI) pump was signalled to start automa-tically during this event but did not start because the steam supply valve to The failure to open has been attributed to water in f
IPCI turbine did not open.
the oil control system.
This problem is being corrected. The unit is expected to be restored to service in approximately two days.
Neither the licensee nor the NRC plan to There has been no media interest.
issue a news release. The State of Georgia has been informed.
Region II (Atlanta) received notification of this occurrence by telecon from the Resident Inspector at 9:15 a.m. on June 4.
This information is current as of 2:00 p.m. on June 5.
Contact:
GKlingler, IE x28019 FNolan, IE x28019 SEBryan, II x28D19 Distribution:
Transmitted E St
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CommisAioner Bradford S. J. Chilk, SECY Chairman Hendrie l
Commissioner Kennedy Commissioner Ahearne C. C. Kammerer, CA Commissioner Gilinsky (C^.3b' ACRS (For Distribution)
Transmitted: MKBB.-W@':r P. Bldg ' //, M J. G. Davis, IE L. V. Gossick, EDO B. R. Denton, NRR Region % _iro10 E. L. Ornstein, EDO R. C. DeYoung, NRR R. J. Mattson, NRR
J. J. Cummings, OIA R. S. Boyd,'NRR
. R. G. Ryan, OSP H. K. Shapar ELD,
SS Bldg ((. 40.
R. Minogue, SD W. J. Dircks, NHSS S. Levine, RES j(
PRELIMINARY NOTIFICATION
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RC TELEGRAM FORi%T is Jun a
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l'NITID 51 ATE S I;UCLI AR REGL*L ARTJRY CO.
03I4LtTOR Of IH5PECT10N At:D EllIORCLf'.Lill a
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1011%RIETT A STREET ATLIJi1A, GCORGIA 30303 CE E
HATCH l'H1T 2. DDCEET flD. 50-366. tiDTITICAT10!I 0F REPORT /i 5LDJECT:
Il0. 50-3GE/1979-45. Rgv.1 ND11f'ILD: Ross F. Rogers
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i DATE: 6/7/79 DATE: 6/4/79 T il!.L ' 3:30 pn j
i DISCRIPTION OF REPOR1kCLE OCCURRLliCE f
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Initial Condition:
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During reactor pcwer ascension, at 2387 mega watts themal, a reactor sc The reactor pswer 7
occurred at 1850 CDT due to a condensate systern trip.
level fall below 1330 counts Per second.
Na ture of__0.c,cu_rrence:
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Dse to the ice level in the rear. tor at 1855 CDT the HPCI Syste:s was re d an to initiate and pump water to the vessel.
- Although th I,
open.
Iri,rdiate Corrective Action:
3.5.1 The HPCI was secund and the requirements of Technical r
co nPlied with.
System to operability.
Cause:
One of the HPCI pump mechanical seal cooling injection water Ifnes wasThis leaking at the threaded connection at the pamp casing.
The bracket drain cavity drain line had a valveT the bracket drain cavity.
The inttalled for reasons presently unknown.
the Icak to fill the brar.ket drain cavity to a paint above the shaf t.id tight pe
, adjacent bearing housing does not have a liquThis allowd water to enter tf Had the re qui re d ).
This water then drained to the oil system.id not have af fected the braclet drain cavity.
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brar.ket drain line valve not been closed the leak w line valve was not listed The bret.ket. drei n on the syste:n PalD.
oper4 tion of the HPCI in any way.
in the systten velve lineup procedure nor was it sh 20w' l Y O G f V c i Y p (p 7
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RO Telenram Cont'd
. June 7."1979 c.
5,uppl. e_w ntal Correc t ive Ac t_to,n:
o The reactor was bmught to the hot shutdown condition,
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The leaking seal injer. tion line was rtpaired by replacing a section of b.
the leaking line.
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The oil system was drained, flushed and refilled tarica.
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I An investipation of. the all system was made to detemine if there wers The oil conter in the d.
any other ways for water to enter the systers.
i system was Mentified as being a possibility but pressure test pruved the No other possible water sources were identified.
cooler to be good.
L The inspection The turbine bearings were inspected for possible. damage.
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reves t ed a lite new condition.
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The velves in the bracket drein lines will be lo:ked open prior to startup L
and a study initiated to detemine if the valves could be renoved frto the f.
In the interim this v.alve has been added to the systen valve lineup Ifnes.
procedure.
A study has been initiated to select a method whereby water in the oil t
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systems of RCIC and HPCI turbines may be readily identified.
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h Until the above study is conpleted the oil systers on the HPCI turbine h.
wl11 be sampled on a weekly basis.
I initiated te detemine if the seat injection lines
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A study has been 1.
need additional support to help prevent future leaks.
L Status of Redunden,t,or Backup Syst.em.s!
The RCIC f ailed to operate but the Autostic Depressurization Systea,
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f Core Spray System and Low Prtssure Coolant Injection System were operable.
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livset To,0,ther Unit:
A 1stk of a water detection in the turbine oil systerns msy be a problees p
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with other steam. driven pu:ngs, An investigation was made on Unit 2 RCIC system and Unit 1 HPCI and RCIC Systems to deterndne if the same valves exist in the cavity drain Ifnes.
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L The results are as follows:
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- 1. " Unit 2 RCIC - No drain line. The cavity drain hold is open and
, ill drip to the pump skid.
w Unit 1 IIPCI - Drain line to floor drain with no valve installed.
Unit 1 RCIC - no drain line. The cavity draf n hole is open and will drip to the pump skid.
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4 R0 Telegrom Cont'd June 7, 1979 N
J.u_f.ti f t t a t ion F or_,Co,n_t_i nued Opt ra tion:
fio detectable nmisture was The stop and contml valves were cycled to insure proper operation.
The llPCI system ot1 was analyzed for water.
j An operability test will be perforned as soon as reactor Condittans pernit.
present.
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July 6, 1979 PM-79-601 PL*:;T E. I.
ATC-:
License.Even: 7.eocrt Docket
- o. 50-356 Unitec States 'Nelear F.e;ula :ry Oc=ission Office cf Inspe::icn anc Enfor:grent Region II Suite 3100 101 Mariet:a Street Atlanta, Georgia 30322
,a ATTENTIO:': Mr. James P. O'Reill'y f
Pursuant to se: tion 5.9.1.E cf Hatch L' nit 2 Technical Specifications,
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please find attached Re;;r atle Occurrence P.e;. ort tio. 50-365/79-59.
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P.lant Manager /
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xc: !!. A. Ilidner R. D. Bai.er Control ?.ccn File 9
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U 5. JUCLI AG fitCULt.ICHY Cc'.'.',;;:n 4 0?;*1 *;G '
L.,EF SEE EVENT REPORT
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..,?. I I :n EVENT cEL:ntPTIC'J /.!J3 PGc3aELE j';7EC.,ENCE$
P,eactoT 1
D i At 1220 CC7, MSI'/ Fast Cicsure Startuo test for l' nit 2 was initi :ted..
- t g j scrcr. ed as a result of SIV clesure..Durinc the resulting trar. fent sRCIC and x
y Technicai scets 3/4.7.3.5 l
~0...Lboth isc13ted en steam line hich differential pressurer The ADS syster 3! l arid 3/2.5.1 Action A were met for both RCIC and HPCI respectively.
Eoth the PCIC and ':C; ;
31.e.:. :.:r_c....L cacable of derfer-inc its ' intended fur.ctien.
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At time cf occurre.ce L'r.it 1 was in ccid ;
_T,ft:~..er.s were successTully started ca-ually.
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(conti..ued) t rr! i shutdown conditicn for rainter.ance, hanger modificaticr.s..and refueline.
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TF11:CIC and F:C: sys e-s isolated en steam line nic.h differential cressure.
i' I.Lisoitted
'.5ev were ranua11v started and later secured ucon c3 rietien c' is!'i rest
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' Test shco cers onnel were instructed to c!.~:k.calibratier. cf I
Tel i Cicsure sta-tuo test.
Calib-3:icns fer
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Baxley, Georgia 3i513 Event Description and Prc5able Ccnsequences (continued)
There have not been any sicultaneous system isolatiens previcusly en the sub-ject RCIC and HPCI systers en either Unit 1 or Unit 2.
There were no ;er-sonnel injuries, overex;esures, or any release of radicactive C2terials to
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the envircr. cant as a result cf this cccurrence.
Cause Description and Ccrrective Acticns (continued)
Cause of RCIC isolation is not known at this. time ar.d is under investigation by both utility ar.d N555 su plier.
Switch 2E41.':305 setpcint was within acceptable rar.ge; however, switch 90Ca was out of calibration.
EPCI switch 2E41-M003 wts re-calibrated and returned to service.
Opinicn is that swit:h calibraticn may not be scle cause of E?CI isolation an.d is aTso under in-vesticatic.1. All switches invc1Ned are ITT 2arten Mcdel 253.
Results of invesd;ciens and any folicwup testing will be reported in an updated LER.
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'Jarrative P.eport
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. for LER 50-256/1975-59. Rev. 0 On June 27,1979, at 1220 COT, the MSIV Fest Cicsure startuo test was init-icted for liatch Unit 2.
Initial reactor power was 97S (2255 7'..'t).
Reac-tor scram resulted due to M5:V closurest RCIC and HTC! systers isolated on steam line high differer.tial pressure after the reactor scram.
Both systecs were manually started by plant c;erators.
RCIC system, after man-
-ual start, ran thr:v;*.out the duratica of the MSI'.' closure test. ~hPCI was started at 1238 COT to raise water level and was shut ccan at 1239 COT '
Vy'pla-- perator.
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Immediate corre:tive acticns initiated ty plant toeritiers personnel tere to manually start both R IC and MPCI systems.
Syste s were su::sssfully started manually.
Redundar.t systems were available, and capabic Of ;er-forming their intended functions.
Test shop pers nnel were notified of the systems isola-icn and were instructed to check calibraticn of steam line high differential :ressure s4it:hes 2E51-N017 and1018 (RCIC)and 2E*1-NC04 and NCC5 (HPCI).
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Test shop persor.nel found the calibration of 'the RCIC switchas to be with-Jn an arre., table rar.;e per procedure re:uirc ents.
Cat.se of the RC:C sys-
' tem isolatier. en high cP is unkn:wn at this time and is under investigation
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hy both utility ar.c the N555 suppifer.
Per the re:Utmendation of the NSSS supplier, instrc.cnt piping fcr RCIC switches 2E51-N017 and N015 is being mcdified to correct piping gec e:ry which could be a fa: tor in the isolati:n of the systen. The NRC residsr.:
inspector was informed en 7-4-79, at 1010 CDT. of the instrument piping m::-
ification.
IIPCI high steam lir.e differential pressure switches "004 and "005 were chee!:ed for calibration. Switch 2E41 "005 was found to be accept:b e; new-ever, switch N003 was cut of calibration.
Switch 2E41."CG4 was recalibra:-
ed and returned to service.
Incorrect HPCI switch setpcint may not have 8;.r.17..T.:.4 cause of system iselation and will also be investiga:ed.
Upon ccepletion c.~ investigation of HPCI and RCIC isolati.:n pr:blem by utility and "SSS su:plice, suppiccantal corrective actions will be taken and reported in an update to this LER.
At the time of the occurrence, Unit I was in a cold shutdr.wn condition for maintenance, hanger redifications, and refue ing.
Result: of the Unit 2 investigation and corrective actions will te censidered f:r a:pli:ati:n Unit 1 systens.
Previous failures of HPCI and RCIC systems on Unit 1 and
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2.::lil be re-evaluated.
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