NRC Generic Letter 1981-22
V-J
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D. C.20555 MAY 5 1981 L LICENSEES-OF OPERATING PLANTS AND HOLDERS OF CONSTRUCTION PERMITS
- lemen
- ENGINEERING EVALUATION OF THE H. B. ROBINSON REACTOR COOLANT
SYSTEM LEAK ON JANUARY 29, 1981 GENERIC LETTER NO. 81-22)
Enclosed is our Engineering Evaluation Report for the Robinson Event. The primary reason for our evaluation.was the loss of approximately 6,000
gallons of reactor coolant water from two separate leaks in the letdown train of the Chemical and Volume Control Letdown System (CVCS).
The evaluation is being forwarded for your information and.training purposes.
The evaluation of the event did not identify any safety concerns or any required immediate actions. There are four areas, however, which are under consideration for further action:
1. Whether a requirement should be placed upon.operating plants to establish a procedure for identification and recovery from a spurious safety injection actuation (if such a procedure is not already in place).
2. Whether criteria for terminating SI should include provisions for isolating charging since charging flow could be considered high pressure safety injection for very small breaks.
3. Whether there is a need for a direct reactor trip on a safety injection actuation at other Westinghouse plants which do not have a direct trip.
4. Whether operation of the isolation valves in the CVCS at Robinson, is causing the system to be 'operated in a manner which is contrary to its design bases.
If you have any questions regarding this evaluation, please contact your Project Manager.
Enclosure:
ccw/encl: Service List
2/O6 ) 3 o 3 %t(
.
I ,-
.V 6'4 ."
1 CeA44. Fajes ALL POWER REACTOR LICENSEES
Docket No. 50-348 Docket No. 50-3 Farley Unit 1 Indian Point Unit 1 Docket No. 50-313 Docket No. 50-247 Arkansas Unit 1 Indian Point Unit 2 Docket No. 50-368 Docket 50-286 Arkansas Unit 2 Indian Point Unit 3 Docket No. 50-317 Docket No. 50-155 Calvert Cliffs Unit 1 Big Rock Point Docket No. 50-318 Docket No. 50-255 Calvert Cliffs Unit 2 Palisades Docket No. 50-293 Docket No. 50-409 Pilgrim Unit 1 Lacrosse Docket No. 50-325 Docket No. 50-269 Brunswick Unit 1 Oconee Unit 1 Docket No. 50-324 Docket No. 50-270
Brunswick Unit 2 Oconee Unit 2 Docket No. 50-261 Docket No. 50-287 H. B. Robinson Unit 2 Oconee Unit 3 Docket No. 50-10 Docket No. 50-334 Dresden Unit 1 Beaver Valley Unit 1 Docket No. 50-237 Docket No. 50-302 Dresden Unit 2 Crystal River 3 Docket No. 50-249 Docket No. 50-335 Dresden Unit 3 St. Lucie Unit 1 Docket No. 50-254 Docket No. 50-250
Quad-Cities Unit 1 Turkey Point Unit 3 Docket No. 50-265 Docket No. 50-251 Quad-Cities Unit 2 Turkey Point Unit 4 Docket No. 50-295 Docket No. 50-321 Zion Unit 1 Edwin I. Hatch Unit 1 Docket No. 50-304 Docket No. 50-366 Zion Unit 2 Edwin I. Hatch Unit 2 Docket No. 50-315
6 Docket No. 50-213 Connecticut Yankee (Haddam Neck) D. C. Cook Unit 1
- 2068 X& -_
zS-,*-1 k 1.,
. . .. . .5 . %. I I t U
DISTRIBUliON OF GENERIC LETTER 81-22, DTi, .,'5/81 Braidwood Beaver Valley 2 Bailly Bellefontc Byron Callaway Cnmanche Peak Cherokee Catawba Clinton ;
Diablo Canyon Farley 2 Fermi 2 Grand Gulf 50-416/417
50-518/519/520/521 Hartsville Hope Creek 50-354/355 Harris
50-400/401/402/403 IaSalle 50-373/374 limerick 50-352/353 Marble Hills 50-546/547 Millstone 3
50-423 Mcnuire 50-369/370
50-329/330
Midland
50-410
Nine Mile Pdht 2 Phipps Bend 50-553',554 Palo Verde 50-528/529/530
Perry 50-440/441 River Bend 50-458/459 Summer 50-395
50-387/388 Susquehanna Shoreham 50-322
50-361/362 San Qnofre 2/3 Salem 2 50-311 St. Iucie 2 50-389 ,
Seabrook 50-443/444 South Texas 50-498/499 Sequoyah 50-327/328 VogUe
50-424/425
50-482 Wolf Creek 50-382 Waterford WNP-2 50-397
50-508/509 WNP 3&5 50-390/391 Watts Bar WNP 1& 4 50-460/513
50-566/567 Yellow Creek Zimmer 50-358
H. 9. ROBINSON
ENGIItEERING EVALWUTN OF THE
T SYSTDI LEAK ON JAIUARY 29, l9Rl REACTOR COL
by the Office for AMlySis and Evaluation of Operat1onal Data march 23, 19R1 M
Prepared by: Wayne D. Lanning Lead Reactor Syste Engi neer of studies completed to NOTE: Tis rort documets results and Evaluation of ate by the Office for Analysis Operatiobal Data with andregard to a particular operatingin event. The findinlQ recoendat10ofs contained onoo1na UC
support of other this report are provided In event. Since the studieS are activities concerniQ this necessarily final, and th ongoing, the report is not do not represent the f~inings and recomendations the responsible promra office position or requirents ofColSSion.
of the Nuclear Requtatoty I
TABL OF CONTENTS
page
.. .. .. .. .. .. .. .. .. . 1
1. EVENT DESMUPTIOli . ..
2. EVALUATI OF THE EVENT .T.......... .. . * * * S 3
2.1 Operaor Actions .............
- 0 0 5 S
3
0 0 * S 0 4
2.2 Charwtng Flow Terminatlon. . . . . . . . * S * 0 5 5 * S
2.3 SafeV Injection Actuation ....... . S 0 6 0 7
2.4 Pressurizer Spray. . .... .. . . .. S *. * * 0 5 7
2.5 Relief Valve Bellow Fa1iluW. . . . .. * . . . S * S
2.6 LetUi Isolation Valves ... .... * S 5 6
2.7 LedLage Inside Contalimeft . . . . .
- 0 S
10
- S *
2.8 Drain Valve and Pipe Cap . . . . . .
- 0
10
2.9 Failure of Fire Protectio Isolation Valve
- . . S 0 0
11
- . . . - S S
3. CONCLUSIOS .S. .... ....0 . .. 0 .S
- S 0.
... . ... . . . . . . . . . . . . 13
4. REFERM. ..
Table Number
1 Sequere of Events . . .. .. . . . . . . . . . . . . . . 14 APPENDIX A - Iformation Provided by Licensee at Meetinq on February 20, 9Rgl
1. Draft Plant Operatina Experience Report Z. Operator's Log
3. Shift Foreman Log
4. Strip Charts
5. Figure 1 - CVCS Diearam (excerpt)
6. Figure 2 - Contaiuent SOW Volume
) I
1. EVENT DESCRIPTION
Table l. problems with both oil PUMPS
A sequence of events is contained in system forced the plant to initiate in the turbine etectro-hydraulic (E-H)
a safety injection signal was gererated a plant shwtdown. During the promess MCS average t~erature. The nigh by a high steam flow coincident with low governor valves spiking open, believed steam flow signal was generated by the of the turbine E£H system. The low to be caused by the erratic operation overcooling the RCS by excessive injection average tperature was the result of (Sl) signal tripped the reactor.
of boric acid solution. The safety injection lOOt to approximately 6% at the time
'he reactor power had been reduced from flowflow average temperature signal of trip. The duration of the high steam v's apparently not of sufficient duration to latch the 0^" train nor close Both were manually actuated. A containnm the main steam line isolation valves.
St.
fire alarm was received shortly after the had occurred, the operators initiated After having determined that a spurious SI
restore letdown) to :ontinue actions (e.g.. reset SI, feedwater isolation, isolation of the CYCS letdown to hot standby condition. During the automatic that the outermost isolation line due to the spurious SI, it Is believed faster than the two open orifice valves (see Figure 1. valves 20UMB) closed leakage past the orifice Isolation isolation valves (CYC-200B and C), or that valve and the rupturing of the valves resulted In the opening of the relief In addition, a pressure surge bellows on the relief valve (CYC-RY-203).
a drain cap to be blown off.
due to the isolation valves closing caused was reestabllshed. Subsequently.
Unaware of these two failures, letdown now The coatafinent pressure containment pressure and dew point increased.
significance to the already decreasi and humidity increases attached additional I
e2 -
W*nOl) about RCS pressure. Letdown was secrad (valves closw and sequeftC
tJ was mad.
15 minutes after letdown was reestablished. A contaInlflt wea but no fire isted. The A le* was identified in the letdown system from the leak in tie let heat sensitive fire alarm detected the steam the CYCS durio the first syst, which implies that this leak occurred In to be In the com i StsUP
SI. Approximately 3,0oo qallons was estfmated row.
based on level indication in the control the pressurizer pressure cont11med After the letdown was thought ti be Isolated, seond safety injection occurred to decrease and the level to increaSe. A
of safeguards equipfnt actuated.
on low pressurizer pressure. Both trains charging flow aid heatup of The level Increase was the result of continued to recover aver" teprttre the primary system (the 14SIYs Wad been closed could not be identified positiWely.
earlier). The cause for the deressurizatiOm Four hours after the first en, a second containment entry was made aad line which was still leaki*g.
the leak was identified to be from a drain isolation valves (see The drain line Is located uastream of the orifice and valve (CVC-?OO) was Figre 1. The cap on the *ratn pipe was missin'
sup had now Incresed to manully closed. water in the contaimnent the two level control valves avoroxziatelr 4,500-6,nnn qallans. Evidently, gallons per inimte becen (CV-4LCV-46OA&B) were leakinq at five to se durisng the second cantairmeat
053 and 1120. After the AraiR valve was closed ewrty, the qCS Pressure conutimsed to decrease.
of the aecreasinc RCS pressure
- Wry steps were taken to 4eternine the cause charging line auxiltawy after letdown had been isolate; e.Q.. isotatinQ
spray, checkina pressurizer relief and safety valve leakaqe. and increasina pressurizer heater output. Te cause was identified when the operators IM 831 11 I I I 11111 I : 11I ; 1: I Hill 11111111
11111 11.4. IMI MINE qIHills I - 11,11
in *e loeps with th pressurfuw stopped tw of the thre reactor coolant p05"
Omt of the two pressurizer spray scoops and the pressume bqan to Increos.
01Mtlicat" of swu valve spray valves was not fully closd. Positive The s"y valve position is RC-455B as te leking valve was made later.
delayed Adentificatiof of the Indicated by demand, not stem position. whiic cause for depressurization- a pr y-tosecodry During this event. steam qenerator samples tilcatat of TO aCll. Stem leak of apprvxiiately n.5 gpo based on activity side. Subsequent samles generator *I' was isolated on t1e secondary licsee has concluded indicated decreasing activity ad no leak. The cvw beWoo agiUted during that the Increased activity was the result of evest- isolation of the steam generators during the relief valve bellows. The cap Repairs were made to the spray valve and the valwes were verified closed.
was replaced an the drain line and all draiN
The unit ws back online on Febrary 1, 1981.
2. EVALUATION OF THE EVENfT
2.1 Operator Actions wrf timly fashion. Data Operators responded to the evects In a systemtic Afte- the plant was stahilized, entered In1 the logs were detriled and accurate.
that their diaonoses were correct the I iceuse contacted Westinghouse to ensure avd no other unforeseen problems existed.
for recovery froa a One shortcmIng Identified was the lack of a procedure Vw1ld be available to the spurious safety injection actuation. Guidelines St actuation. The operators to differentiate betbeen a real amd s~uotzzs for recovery from a spurious licensee Indicated that a procedure will be writtei tts event, resettinq the SI
SI (identification criteria not included). For
. I . 0 0 IMCMIM11 I=21 I II I t 11 W, 11,
. 4.
.- .O "A4w ueerttu re
-%-
oiaeover, prtssurizer preussar.
4 tr *nly efout
- Is '! %*
tc:resslf Clor to the SI ard had Starl'!eA'1 In t, ce -41 sil; a S -
t d r.st~e :,reow-e reset-.inq SI. etrospect nd the spray valve was Ooen, nowever, S: mad neetf I C4.ta *. ol4rft teak a.1 sisce secondary
1.-rldc-CJ ^.jfn 3wou"Is Inttcative of a steam line b"ea valve posi tion recorder indicated systo condi tiors wre stable and the govnor correctly diagnosed the St slwll as spuitows valve IWeq. the operators sfu-!s for tWS event.
actuation M J 9-es f i-Orovemert ul'i have been to test the safety injection SI failed to latct I -. , eam!4u tsolat'on slqnals since one tain of Both were manually actuated. Althou0" both Vt Vow -tiIs faled. to close.
injectior signal, this was not adequate il Cra'.s actuatec on tte second safety averaae tafperature actuation
.titi~tn of omerabi'ity on high steam fiaowl¢.
have heloed substantiatte that t'cfire returnine *a power. These tests could to latC~h the SI relay antl close
. soaw'at was Pm of saf'lcient Duration Z !>arging Flew Tewuutiofon
4 into the a; -.osrn S' actwuai1 occurred twice, no boric ac d was Injected tUnlc. This war because
'a- tSiej on sWvpes of the boric acid injectlon head SCl,50 psig) of the SI
t:nc ;CS s;Stem presssur exceeded the shutoff Hence, the cria1to snms aere xakvino uo s: Icre cte of actuation.
, - '-. .- *rJfsaG the event.
and recoanizinqf
_. - U.c AEt"teS to identify the Cause for toe .jepressurizitiof flow
- -eiia--lzef oray coull cause the dePressurIzation, the cnaraivc terminate a possible leak fro
- iJ! tet1 il:seA vilve CYC-1CV-1211 to ig.1lrary sorsy vave (Ficure 1). This operator action did not 'terminate
- -.
all makeup flow to the RCS. The flow path was maimutned to the RCP seals which would provide makeu flow (appwiOnaltelY 60 Mm. RCS corndIzns (approximately) at this time were: Pressurt a 16i1 psiq; Tavq
- 5cWFa pressurizer level a 56 and iumcreasing; normal steam geerator leve' for the condition; and margin to saturation was approximately sn ss'.
(shift foreman's The charqing line was isolated from 0126 to sometime after 1932 now for log). No consequences resulted from isolating the notsal charging pump head limits.
this event althouqh SI now was not available due to the the c9-arginq However, it is suggested that URR *etermine whether isolating when the system flow is advisable for small loss-of-coolant accidents or has Indicated pressure is above the shutoff head cyf the SI pumps. Westinghouse analyses. The emerqency that no credit was taken for charqimg flew for the ECCS
for terminating procedure for depressurization (El-11 does not include criteria and not considered charging flow. The charging pumps are a part of the CVCS
the clarqIng a part of the safety injection syste at Robinson. However, exceeds the pumps provide high pressure makeup flow %Aen the RtS pressure shutoff head of the SI pumps. Enswrina that charging flow is not interrupted desirable to enhance for the systems employinq low/iediwum heat SI pumps may be safety.
2.3 Safety Injection Actuation The first safety injection actuation occurred on a "high steam line flow/low Tavg' sigral. 'he licensee's review of the event indicated that the momentary flow, in at spike-opening of the turbine Qovermor valves caused the steam a period of least two steam lines, to exceed tke steam flow set point for about 25 -sec. The combination of high steam flow in 2/3 steam lines and generated a main the existing low average temperature of the reactor coolant siqnal.
steam isolation valve ORSIV) closure sional and a SI actuation
-6 _
r*espo0 ed - tne other onwevet. only train a of safeguards Mdi i"moir.
did not actuate. Licensee's train *-, ;sfeouards eqipCent and 11 tne "VS
duration of one Weeond CnServations are that the MSIVs require 4 sICn1 SI logic train latching to close an that the SI actuation relays. Including usec to actuate. Since relay, require a siGM duration greater than 25
1 only the train B latChinq the SI sinal was of less than 25 sac duration, feedwater isolation relay actuated. Rextor trip, inrgency diesel start, B occurred as a consequeace and other safequards equipment actuations for train of SI train B actuation.
Actuation Signals (3q Reviewino the logic diagram of Robinson's Safequard reactor trip siq.al is CP 300-5379-2759 sb A* rev 5) It is seen that the start, feedwater isolation initiated on SI actmation along with emerqercy diesel later Westinghouse locic and safequards sequece actuation. A review of a is derived separat ly diagram (typicalI s1ows that the reactor trip signal signal Is taken of fron the SI actuation signal; i.e., the reactor trip the MSIV closure s1iqal supstream" of the St actuation signal, similar to SI actuation events on Robinson. This could mean that on certain spurious of short slal duration, SI, feedwater isolation and auxiliary feedwater trip occurring.
system actuations wy occur with no simultaneous reactor P-4 interlock (reactor The comparison of logic diagrams also shows that the of SI logic of later
'rip breaker position) in the the Reset/Block feature design. Add1itlondl mie desitino"use units is not provided in the Rotinson of different reactor triz 1--
woul4 he needed to ascertain the significance a direct reactor tr4o on spu -
for Aestinghouse p ants. The nW to provide t
review.
safety injection actuation Is referred to ORR for
) 1
- 7 -
2.4 pressurizer Spray due to lack of spray flow indicati"n The Ope spray valve could not be identified of the valve to close evidently or atual spray valve position. The failure to open as evidened by subsequent did omt affect the capability of the valve of relocating and replacing testing. The Licensee is evaluatinq the possibility outage. Previous problems have the spray valves during the next refueling their location im contain ent been exaerienced with the spray valves and reduces their accessibility for maintenance.
2.S Relief Valve Bellows Failure
4 of this Crosby rel ef valve The licensee has experienced previous failures H51380). Basic imfornation about (number JB-36, Type B. shop drawing number were obtained from CP&L
the valve and the discharge piping configuration and Crosby Valve Company and are as follows:
Relief Valve
- 2- diameter inlet, 3- diameter outlet
- Set pressure. I00 psig
- System pressure, 300 psiq (approximate)
- Dynamic backpressure, 25 psig (specified)
- Bellows tested to lSfl psig Piping turning
- A horizontal run exits from the relief valve before relief tank.
vertically up for at least 12 feet to the pressurizer
.R
valve lifts.
CV. %nGicateo that the bellows falls every time the relief that the %yitem St'ce tie bellows has been tet*te to 150 psi,. It woul4 apper differently from the anticipated mode. Me 4ynaaic
- m..4*Iwi
-*ssssrt probably eiceeds 15n psig (isx times the spect led 2S ps';I.
stalate water from I *e-C'.s t fsa that could cause the high pressure might be steW Condensation or valve leakagt fit the line from tft relief valve v-!o Boric acid crystal formations na also be U --e preswrizer relief tank.
- a5sbtl1ti. when the valve opens, water or other debris in this I In until the zcia U restrict steam flow and csuse a h1qh ytnamic backpressure borvid water.
1,.c is cleared. Also. if Ute line is filled with staq'nat has not te ze'lows say be susceptible to corrosion attack, but coarson Frw in operational beawr. 11eft1fe1d from previous failures and relacements.
and changes vIwIDint, the failure mode for the bellows should be identliied The operation Nessary U prevent ad1'tioeal failures should be imolemefud.
to tne bellows failures
' -e CitS Isolation valves may be a major contributor mll is dIsussed in Sectijn 2.6.
2?S Let " Isolation Valves at Te 4solation valves played a dominant role in the :quence of events X=ci'son. The failure of tP* bellows on the relief valve *as attributed Clos4ng of
'te clostiq of the out board valves KCVC-204A&B) before "c
-
the relief valve.
vw orifice isolation valves fCYC 200BU) upstream of was reached since
,2sewue'tly. the set point '600 psig) of the relief talve system s ar. if the CvCS was pressurized by the reactor coolant T-:' .as tt aporoximatelj I.AOO psi. 'he Cesign pressure downstream of eS' ts ser1es:IEC-20O pSTq. T00 sequential The =e'ation of the
-r C'ICS to be pressurized
-sxa'ton *alves is evidently causing this part of the ty the ovening c a: least tte setonint of the relief valve. as evtdenced r ve rel'ef salve whenever the CVCS is isolated.
U 9 -
tCW A and R (FigWre 11 were In addition to the Isolation valueS. wal"v ti le ig b*', valvefpipe. Both of these closed In an attept to isolate
3LOW gallons (approulately)
valves leaked %ich pefritted a" aMItina'
containment after tV letft-0 yst was thougt to be Isolated.
to leak Into the did not perform any saiiia on thse valves to ensure their The licensee before returning to ptr Once thls we not contaii't isolatin operation These valves are part of the reactor oomlant pressure boundary and valves.
level to conserve RCS inventory.
are designed to close on low ,resste'
of te CWCS raises two concerns:
The design and operation of this part the system to 2,?2n ps1la assu"Il first, the potential for overpressurltzina we closed; and secondly. the the dowmstre' Isolation valves MCCIA)
ibtrew of valves LCV-46nA&S.
capability to Isolate a potential br*A
relief valve is designed to vrevent The licensee has indicated that the apoear overpressurization of the CYCS. The failvre af the bellows does not of tVe relief valve. In addition, furnrtiO
to affect the pressure relievisg have been designed to isolate a the flow control valves (CVC-LCV-460&9)
mwiimw sire break and ACS conditions.
break downstream of these valves for re For tv flow control valives are The functional and testing reqrvllts These valves should be A99 Class 1 since there are no valves not clear.
However, are classified as ASME Class 2.
upstrem and the valves downstream iodteifed In the Robinson Inservice these flow control valves are mot and Testing Program (Reference 4). Since these valves are on the Inspection tc Isolate the RCS on low pressurizer RCS pressure boundary and are desigmet om the valves was not required after level. It Is not clear why .aimtenance rewrmifg to power.
they were known to lea and bore
- to -
a s11al loss..f.coolant *"v"t Iside goth of these concerns could lead to
' event ill wthin the scoop ofSIR an .n11S small containment. This postul wfrom mit a row safety conce". 'IO"vt'.
break loss-0f.Conlant acci~ent and the CMC could he 9Tpolvotoo, an operational consiieIt1i". 0o oW'esWsu551UiZ
solation were close before tVe outbcaM f provided the orifice Isolation valv"
Correctlnf the valve closiw sequence for Isolation woult also reduce valves.
the challenoe to the relief valve.
2.7 Leakage Inside Containment fato The licensee has acknowle4"e that the quantity of water that lelef The estimatoda6.nn0 qallnIs 1coerospondino containment can only hp aproxivutef.
f IndicatiOn
4pPrnfin^ately 1; In the sump) ts a sMll fraction nf the raw to zt tSee FViure 2). A mass balance was in a 65,000-gallon capacit sup nor volume coetrol tank level are recorded.
possible since neither charaing fln had been restablished bee 635 The major leak was after letdown flc uallons m¢poximately one half of the 3.rrf and O050. This could account for letkikn at wr unknown indicated at MP5n. The 4-ain valve Could have also been letdown was restored (&oppotRately reduced rate from the init4al S'- umt1l on the relief valve also conT ut el ten minutes). The ruptured bellows with Sump. These sources in cOWiftaition so'e amour' to the inventmry I1n the can lead to the concluston that all tne inaccuracy of the su'o iearsuwents the leak sources had heen 14ent@flfel.
.alnlrin Volvo and Dir'p' Sp
4 hy valve was Cwf-?nOEF :.ee clqurp 1) not CIC-7ndC as rrvrfoo'
'he leakitnn jxWl¶taod the leak r4tes an ontoV if IF (Reforence 1). This helps to t2) and the tE evaluation.
water reported in the _E° 'Referece
.tssinQ cap on the pipe was taShe The licensee's explanation for the
- II
tte Drfice Isolation valves clos. a pressure pulse Was applied to the cap. Since tte valve ws partially oe and ti cap not tiqhtly valve an sacugrd, the cap was blown off. The lice*g" believed that vibration in of the valve and the CCS (induced by the charging pumps) caused movent
11, 1180 during a refueling cap. Th valve positioi was last verified on October pressure reducina orifices.
outage. Since the drain pipe is located close to the in the the now Instabilities at these orifices could also Induce vibration CMCS.
Most valves have All drain pipes with valves have been verified closed.
been chained and locked.
2.9 Failure of Fire Protection Isolation Valve Injection actuation, When a Phase A isolation signal was generated by the safety failed to close due one (FP-248) of the four containment isolation valves in the line closed, to a tripped breaker. Since the other isolation valve containment Isolation was achieved. This failure had no bearing on the leak and was a separate reportable event.
3. CONCLUSIONS
unrelated failures:
The event at H. B. Robinson involved four separate, somewhat leaks in the
(1) pump failures in the turbine E(C system; (2) two separate valve;
CYCS (related failures); (3) an undetected open pressurizer spray and (4) leaking valves in the CYCS. The event did not appear to Include any safety concerns.
to NRR for The following areas of review concering this event are referred consideration:
- It a S. ethra requireent should be placed VpoW _fttfg4 Pnfts to Ostblish
1 W afety
- procedur* for Identificatilon Gnd recovery frw a sw"
is prlae).
injection actuation (if 5ilh a procedure Is "alrAe,
~ Sion fCW
b. Mether criteria for teinitlfig St should IRleft
1hichtoressure Isolating charging since charging flow Coult a coomiti safety Injection for very s&ll Iress.
for a direct e*act trip o a Sda'oMs safety C. Uhether there is a ne NC*t NM*ea Injection actuation at other uestlnghouse IPuT& lt Wch direct trip.
tS at RMI"tOf d. whether operation of the isolation valvet in VW
I S CO"XFrY
Is Causing the system to be operated In A wMne Whitt The closing sequence f thV IS61@iI0 vlves to Its design bases.
ta e SetVoCnt appears to cause part of the CVCS to be pressiwrize fatllwt of the of the relief valve and may be contributifn = thW
relief valve bellows wh"never the system Is tsolateC.
evemt ftrtel'. A foral AEO0 did not find any basis for a need to study tts, respone from NPR Is not requested.
txale Can oaPerating Th1s event and the operator' s response provide a 7=d Ttoees favr tInoation and oxoet"mence which should be disseminated to other ttra1 frf puposes.
!
_ 13 -
4. REFERCES
H.S. Robinson Event on
(1) tMorandum, H. Woods to F. Jordan. Svbjct:
January 29, 1081. dated Fehbruey 12, l9"l.
Steam Electric Plant, Unit
(2) Licensee Event Report 81-nffS. 91.8. Robhwson
2, Docket 5f26l1, dated Febhwry' 12. 16R1.
on
(31 "eetinqwith Carolina Power wd Ligt CMpany In RethelA
Fthruary 2n. lORi.
H. R. Rohinson Steam
14) Letter, E. E. 'Itley. CP&L to S. VWMga. Subject:
and Testing Program, dated Electric Plant Unit No. 2, Inservice tmspectlon
-arch 10, 19A1.
. 14 a Table I
vrniirMcU os rvEwTs jaflUay 701. Lq~ )M
Plant at 100'
I,. .
Orloary to secoMary 1.k of Irn^1ItE'l OF ENC wump alrealy out of service dut to vtibrtioA.
500 O A ENC oil pump seal leak.
0s41 Started lead reucto10n.
0S42 *ided boric acid to RCS.
pump runninq, OA charging pup
0543 Started *C chaNrtng puop. "3d charninc Inoperable.
CVC-Ve0C already open.
Opened CVC-2'1O0 oriflce isolation valve.
"49-
130n Continued to add boric Acid.
pUmp 00 tgIOratIc FWP ht-havifr.
'WI1 ftn1p#A '0' ..dwftitr W.IMp And Cn"AeQ'tAtP
setpoint (K4AVFV alarm.
MMn Tavq reached low 'avn WI62 Generator Output hreakr opened.
Turbine governor valves Spike open.
on high steam flow/low Tavo.
St siqnal and 4S!V c'osure signal St train '8 automatically started.
equipment started.
Phase A isolation; safequard B emergency Reactor trio nn S' slqnal.
Tavq a 53?"F.
Pzr pressure
- 721- psln.
Pzr leve' * 1r-.
0625 Fire alarm in contaisoent. to noemina of CTCAV-203 relief valve.
Pressurizer relief tank level alarm due cap was blown off.
Bellows ornhahly ruptured and drain MS Ys clospo lanually. 4 tI, AFWP, RH. manually.
Sl train 'A" starteA manually. Started "A(should have automatically closed Letdown valves CCV-AFAA&B manually ClOSed on PZR level of 11.).
067 Reset St and feodwater Isolation.
would not oaen (instrument nA34 Atte-oteW to restore letdown flnw %ut CYC.?nnA
a'r tysrsm lolwte4 on Phase A Isolation). sionals.
RestoreA let4wftn flow after resetting Isolation (-2000 9sig).
or*ssur& started iecrlas'inq sharoly Pve55urlie- started lncreasina.
Containment new point and pressur0
from the coolers.
0637 Received condensate :ollection alarm manually.
01esel aenerators A ant B stooped
a 6
- 15 .
064O Isolated letd flow. (Isolation valves closed from control room.)
Contalmnt d" point and pressure decreased.
Pressurizer pressure still decreasir'o ( i;n psi').
Tavg Increasim@.
Pressurizer pressure increaslnc.
Notified NRC by ENS.
0650 Containmmnt sun level ind1cated approximately 3000 aillons.
0700 First contauinmt entry to check for leak and fire.
O070 Second SI actuation on low pressurizer pressure.
Both trains rW all equipment started.
Pressurizer pressure a 17I5 psiq.
Pressurizer level
- r01.
0705-
0727 Operators attept1na to dtermine cause of depressurization.
0722 Steam dumps opened manually to control pressurizer level.
0727 Reactor coolant pumps B amd C stopped and charqinc line Isolated to eliminate possibility of leaklnq auxiliary spray valves.
Increased pressaiizer beater output to maximum.
Pressurizer pressure started 1icreasinq.
0729 Continued cooldwn uslna steam dwups.
0735 Pressurizer pressure increasing (1 172n).
Tavq cofstant a S40.
Pressurizer level
- SoM.
073R Stopped diesel aenerators A&B.
0741 Stopped 80 lWI pup.
0744 Opened breakprs on containment sump punos.
OR25 Secured St pivs.
1000 Continued plant cooldovn.
to secordary Sample on 'R steam aenerator indicated O.; ape primary leak. Isolated B steam aenerator.
Second sawle showed decreased leakage 0n.25 gpm).
1120 Second containmelt entry. Found ClC-200E open and cap m1ss1na.
Found bellows on relief valve CYC-213 ruptured.
Contacted Westinqhouse.
- 1.0 .
IFIm &ock.4 10f 9?sWsr St.
1230 Clow M00.
solte0" letdo by closing CVC-3090.
tallons.
CoKOMt sup level was #,SOO4.0
va1lv
1"S Ol 0e9lg VW out of ServiCe du to leaking relief p for operatlO! after COMlet1ift surveillance tists.
lA3M AlIqgd A' charginm (late valves.
ntry) TaitSd prtssurizer spray
1013 Started .'S RCP.
IQt% Start" "CO RCP.
i servict. fttFv excelS
(Latr) #l*M c' OP0164n1 lite &ndCTCS leton lIt lipe from survice.
spray valve
2315 Spray valve 1RCS-49% Identifies as leaking leak Identified.
So aditit1on primary to secondary Jaawyr 30. 191 at IMO plant on-line
WPONh A
Iv LICOM . AMWt ON FEBRtUARY to, IMi twomIgtroN PA* oEt Contents:
bPOrt
1. Draft Plant Operatim EaPIMl
2. Operators Lop
3. Shift Forema Loq _
4. Strip Charts q. fire I - CCS Da (sexcerpt)
6. fle 2 - Contal Sa Volga I
?1AWr W2tA11 1o vMMI 12CV 1w0nuT
k0t R. I1t Janary 29, 1981
2. Identification of Occulrncl by & -High Ste ine A) JA spuriousaiety Injection signal initiated now/Low Tsv" signal.
line draln valve CC-200E.
5) Reactor Coolant Systm 1ek through letdown a second *safet injection C) Primary plant depressurilation leading to signal- signal initiates by a -Low Pressurizer Pressure'
3. Conditioms Prior to Occurrence progress to repair a secondary A plant shutdown to hot standby vas in at 100: reactor power (72! We)
plant problem. The unit had been operating and temperature.
with normal Reactor Coclant System pressure Approxil~te)
4. Description of OccurreacC (All Times Are safety inject1on signal Lnitiated A) At 062L hours on January 29. 1981, a was manually started at
"r train of safeguards. 'A" train equipment
0625 hours0.00723 days <br />0.174 hours <br />0.00103 weeks <br />2.378125e-4 months <br />.
ical and volume control h) At 0635 hours0.00735 days <br />0.176 hours <br />0.00105 weeks <br />2.416175e-4 months <br /> on January 29. 1951, the che bega= decreasing vith letdow systm was restored and system pressure Letdown was secured an increasing containment pressure and dew point.
at 065S hours.
injection signal initiated C) At 0705 hours0.00816 days <br />0.196 hours <br />0.00117 weeks <br />2.682525e-4 months <br /> on January 29. 1981. a safety both trains of safeguards.
-DRAFT-
1
5. hjiE tiOS of Aisereft Cause of occurrence
- A appz1*Itelt 0400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br />, "A" M DOS electro hy4dulic (1-H) oil Pump developed a sea look. "fr&- ouS Pp md ben t l out of serwice earUer due to hih vibrations. Az 0541 Murs, the decision was md to signal due to the 10
sbut doWn to hot standby before receivin a trip on tbS
of t-l oil. Attacbent to. 1 contains .dditional Infouatice failure of the 4 Oil Systm.
output br"kersa.
AJ 062 hours. towdiately follovimg opening the generator b! * "ig4t Stem.
the reactor tripped and a safety Zzjectiot was ix:tiated Line flov/Lw/v T "uignal. Only 'r tr:aIn of the safeguards was activate.
hours. t: was Deterulned
"A" trait equipmet was manually started at 0625 and :he fact that the that the erratic operation of the E1- Oil System
4ad operators re switching from "A" EAI oil pump to "8" -B OL pm The resul:ant steat lo'w s:ie was the governor valves to spike open.
.ine Tlowlow T. " sign. bu t:t wits hIgh enough to cause a "igh Stem insufficient duration to fully Latc' the "C safeguards train seal-Irt
-e avs relay. The seal-in relays in the saf eguad trains are latching mode co mechanica.1.'
that requirs a finite period of ti5 In the energized o. ' contains additinual latch them into the losed positin. Attactent information on the partial safety injectio.
frc the Higth Steami tg The stem line isolation signal th wa generated to allow the _ain st flow/LAW T " signal was of infficielnt duration
@f 412 The orven was reinstatC so quICkly isolation walves co go shut.
-DAFr-
- 2
-DLAT-
cce (coalnued)
S. D"imton of Arcent Cause of Occur valves were unble to t3MVel far enoush after the IsolAtion signal that the slanually to Isolate the *tem f lw. The Maiu steam isolatin Valves Were thereby dmaad follwin the reactor trip, abut to rduce the secondary stam no load s.tpoint.
pioting the return of Ton to the safety Injection cwditons did not At 0627 bours it vws determined that spurious. The safety injection and exist and that the initiation was The checal vlum control feedvtcr isolation signals were reset.
hours. The Reactor Coclszt Syst letdown Systt was restored at 0635 but whan letdown was returned to pressure had been slowly decreasing, and dew point began Sincrsinig. Another service, the containment pressure conditions was a fire &Zarn from the indication of abnormal containment deck which was received at approximarely area of the contaimrent operating hours with leator Coolant Systez
0624. Letdown was secured at 0650
containment entry rade at 0700 hours0.0081 days <br />0.194 hours <br />0.00116 weeks <br />2.6635e-4 months <br /> pressure at 1850 psg. The initial the abnormal conditions confirmed that te RCS leakage wa to Investigate fire existed. A subsequet containment fro the letdown line and that no the source of the l2Ak as valve entry at 1120 hours0.013 days <br />0.311 hours <br />0.00185 weeks <br />4.2616e-4 months <br /> further identified llie. which was found open and the CVC-200E, a drain valve on the letdown from the opes drain valve was pipe cap missing. The leak that resulted a-.d letdown air operated valves closed approximately S to 7 gtp with the flow established Tbe leak was coe- approximately 100 gpm with letdown CVC-200E. The ltdow= flow was not pletely stopped by shutting valve was fo-jnd ad repaired- Additional restored until after the condition and contalit fire alarm can be found information resarding the RCS leak in Attachmnt No. 3.
- pgurr- -
Occurract (CotiouU)
S. DsUnstin of Auotwrlt Cause of vS1Wv clo*0d, the pr.ssurizSr owever, evn with the Letdom contro:
pressure continued to dweres, l U g to the secod safety injection
. Both trais
1nit atloI at 07S hours from a Lw Pressurizer Pre"aue as 4asfgne. At 0727 hours0.00841 days <br />0.202 hours <br />0.0012 weeks <br />2.766235e-4 months <br />.
of the satesuards equipuw't functioned O4OInt pump sel injection) to charging was isolated (except reactor and C' reactor coolant pups were SllinatO auxilary spray and "'"
valves from circulSting cooler secured to prevant the pressuriZer spray lnte the 7ressuriser through the vater from the Reactor Coolant Syste It was subsequently discovered spray valves, dtcresing the pressure.
reactor coolant loop had prob- that the pressurlztr spray valve from The ;resurx15r pressure imedistcely ably opened and not fully ressated.
h reactor coolant gyStCi Tc mas stabillred at started co increase.
7ressura coctrolled by the pras- approxiately '205C psig and 5350T vwth by te secondary sctam dump.
suriter heaters and teaperature concrol:-ed infornitiot cc the reactor coolant Attachcent Se. ; contains addition&.
the s;ray valv malfunction.
systcs pressure transient caused by pressure. pressurizter level Coincidental with the decreasing pressurizer was increasing. This was caused by to fa-ctors. 1) The charging flow g ar Increasisg the systen vcluse, from two charging pups was .aintainxi CC-Z0. Te slightly open including the sst*2 losss through the pressure to decrease. 2) The pressurizSe spray valve was causing c" to rb. s*ovly increasing RCS
density changes in the reaccor coolant ralattvolr cold watsr added Sv the tmperatures and thC heat wp of the
'.ase factors combined to charging Syste :aused the systm to enpend.
level. The arrin to subcooling remained cause an Increasing pressurizer
_ _
t-
CauS of 9CCurrenCe (Continued)
- . DsuIton of Apiet trrasien The iniaum subcooline greeter than S$Or throuShout the antire coolant system pressure at Mrgin occurred at 0120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br />, vith reactor
1620 psig and tmperature at S510.
CVC-tV-203, lifted following the The relief valve on the letdown line, apparently due to the sols- tist safety injection initiatiOU. This was closing slightly faster than the tion valves, CVC-204A and CVC-2041.
and CVC-200C. or leakage past one orifice isolations, CVC-200A. CVC-2001 This caused the pressure between or mort of the orifIce isolation valves.
pressure for CVC-lV-203 (600 pelg).
the valves to increase above the set closed, but the belloas had The valve rcset after the letdovn isolations information regardiqg ruptured. Attachent No. 3 also contains additional valve CVC-RV-203.
6. Analysis of Occurrence Oil System had occurred within approxi- Beveral problems with the turbine E-H
trlp and safety injectlio on Mately one week preceedilng the reactor to the Initiation of the January 29. 1981 which could have contributed ev t. These problems are *simrisedas follows:
with water due to a ruptured £E-
1) The X-R oil had become contaminated to this vent. However, the oil cooler approiimately one week prior end restored to spe%.'ficaticn
"- oil had been purified (replaced)
this contributed to the prior to this vent. It is not felt that following problems.
developed a fatigue crack
1) On January 28, 1981 "S" E-H pump unloader this nipple, air was In its discharge nipple. While replacing of the systsm. When introduced into the "3" E-9 oil pump portion
-DIkFT-
C
0. "Anlzelf Of zourfrenc (CMUntl"
"a" g24 oal pwwp wes retearted. it caused esxe@S1vs vibTraitU5
-Al £4 ai. tPU was Mctrted and th Mhout the L-aM Oil Syst§0-
05" T-14 oil pUM was secuzd after a brief perisd of OPeration.
oi- V oI Januar 29
3) The seal leak which developed on "A!$ E-I
1951 which necessitated t turbine shutcdOn is felt Co hzve been vibiratiocn caused by either age or CMe Secessivi-SySC
4) As the sel leak on 'A E- ell puap becae laqrer during the re- operators decided :o asining samnts of the tcttze shutdown, 0he
- in order to run "B" £-H oi. pump des;::- the vibration prcb;
allow the leak to be iso:Ated so a nomrl
%urblze shutdown could be completed. Ccinc;-eta.'-" -2" E-H *LI pumo vas started as tbe
'ten -ba generator output generator output breakers were opened.
Load control to smeed breakers are opened the zts+/-ne witches froa control.
caused the srbine governor One, or some conbination. of the above probab!7
7e exac: cause cannot be tccrmiLeCd. Ths caused valves to spike opez.
on a low rse~tc coclant sys:en the first safety injection in.tted line flow. The high s:eam average teperature coincident vr :h high stean
"**5" safeguarts train was flow was of a very short duratiac. thus only sz:Ation valves rcma. tdopen.
activated and the main steas open since it had las: been Letdown lnc drain va-ve CVC-2WCE had vibrated verified shut os October U, :.SC It is postalatec chat the pressure caused %he ;ipe -ap to blow transient caused by cne .ecdowu :.zne Isolation off. 7hus,
- Reac:or Coolant S-stsm leak existed.
) )
6. AlSIS of Oc ccu @ (Cotuitifkud)
PresSure was caused by :re failure The contimld decrease in pressurizer
"C" reacter coolant srste! .oc'p of the pressuritar spray valve from during thc transient. The event (RCS-4553) to fully shut after opening to the the letdwfn relief line lifting identification was complicated by that there were two separate leaks.
pressurizer relief tank- vhich indicated
"C"
decrose was stopped when "B" and The Usactor Coolant Syste_ pressure to and the charging line was isolated reactor coolant pumps were secured the pressure decrease stopped, operator elniziate auxiliary spray. With hot Systm was re-established and normal control of the Reactor Coolant shutdown conditions were established.
at 062' bours, the trc vrotcctilon TollowinS the first safety injection did not shu: autoaticaC.1 and had to contairelmt Isolation valve FP-248 on
'o. 5 contains additional inlorrazion be manually closed. Attachment contaiment iscla:icn valve.
the performance of the fire protection for this event is prc:,ded as A s*uary of the PZSO computer output Attachbent No. 6.
7. Corrective Action with now oil.
A) The £-H oil was completely replaced
"A" E-H oil pump and unloader were replaced.
B)
on "B" E-H ol: pt.p were replaced.
C) he unloader and discharge nipple stroked and vaive p0s1- D) The valve stes on RCS-455B was lubricat"e, valve will fully close. RCS-455A
tioner was adjusted to ensure the was also checked for proper operatios.
-DLAFT-
-PAfrr-
7 .eeStvL ACUM (COetimUid)
SIMIar Z) CVC-200t vs lockd closed Md CM pi"e CAP Was rlAced.
valve La the letdown ad cbsrg le & Were also locked close or otbrvi verified to be serd.
7) The breakr o current trip saints an tbs four tire Protectios fttsi costarmt isolation ualves 'm be adjusted and checked to Lasure proper valvc performwc*.
C) The eent was fully analyzed bw the plant staff and Vestizghousa, that and the results discussed vith the IaC, esion Sl. to ensure retcrnuhr all safety concerns wure idencif ed ad rewolvod prior to the ut to operation.
.mg _
UaitZ Operating s0iFTJv'r II
/ a-a naT
I 4A34_ /el ltvdl
. ,. / /
. 2- ."I-
Crexa Hanager
-DRAFT-
r-DSAIT
SIQUMNCE OF EVENTS
0S41 Unit *hutdown vas initistod due to E-H SYstem trouble.
0
0620 Tavg reached the low Tavg setpoiat (543 F) during plant shutdomm.
system.
062; Generator output breaker is opened removing unit from Load on unit is Ah.
No. 1)-
Turbine governor valve(s) spike open (see Attachment High Steam Flow/Low Tavg signal generated.
4SIVts closure signal (see Attacnment No. 2).
).
SI signal, train B" actuates (see Attachnent No.
5).
C' isolation valve FP-248 fails to close (see Attachment No.
Minimun Tavgn S32°F (based on incore thermocouple).
PZR pressure
- 2100 psig.
ZR level a M.
Fire alarm at Ct' operating deck (see Attachment No. 3).
0625 Pressurizer relief tank level alarms from C'VC-203 discharge (see Attachment No. 3).
to decre"e (#" A ttCesC No. 4).
0625 (Concd.) Prtmary pre*surr bales
"SVs mayay closed.
SI trfl "Ar equipamt m1maly started.
-
Lerdown yalves LA & 5 sMAfly shut.
0627 Manuafy reset SI.
C635 Restnred letdown.
Lucrease.
Cont:ignmnt -low pc.rnt and 9ressure begin to system).
0650 Isolated letdown (suspected leak in letdown olds steadY .
'56 .avg reaches maxim= vat ae of 55:TF and P R pressure I' . nC Psia.
PZR level a 50.
(see t&:C:enttNCo 3).
070C Cantaimeflt entry to check for leak anc !ire
0705 Second Si signal due to ow PZR pressure. 1715 psV.G.
Both "A" and e.tavns atvse.
depressurzzstC0n. The o7c5-;:'72 Operators attempt to deter2Ln* ;ause of foilowing equipWe.t vas cmecked:
-ISA?-
O7CS-0f27 a) PZ safety Valves flow1Infcitors.
(CorAtd.)
b) PZt P0V discharge line tG.rstur8.
C) PZR block valve positioc.
d) P2B relief tank level.
PZR relief tank pressure.
f) PZR spray valve poItLo (the valves indicated closed but since this 1udic*tiCU La dea indicDtioU the valve controllers were again Ma ly closed).
using the secondary
072' The RCS temperature wa lovered slightly pressurizer level.
stean dumps to help control the increasing Tavg - 5490F.
PZR pressure a 1620 psig.
PZR level a 62.
0727 Thc charging line was isolated to el-imnate tke possibility RCP "B"
of auxiliary spray causing the depreenurtZAti~n.
of main and "C" wera stopped to eliminate the pissibaLIty spray flow causing the depressurization.
Pressurizer pressure begins to rise.
0'35 Tavg a 543PT.
PZR pressure
- 1715 psig.
P7i: WVvuI - '0L~..
)SIO pZR presmawe stabilize.
RUvs
- 535OF.
PZR prossurO a 2050 SOpl.
PZR level
- 452.
toad cgcntim5t entry -a isolated CVC-ZOOE at 1230 bour.
1120 Made
1o '-'9-81)
c0
OUicuaiLOU
to San ;:-L8. Review atnd analynLx of tranaient wLth 4istinglhOUsR.
ut trannfisn't Wit! !RC ello&C It.
identlfiLd " 1"lem2 sPray valve.
231! t;.-29-81) aCS-653 Positively
.7,C i:-I-B1) Plan: on-L.ne.
-DlAF:-
I
CDM=r go. I
SYS si TAILWX
Thn - System bad wM rzecwe sq*ralr probLems prizr ta the trlanSt c
1-29-81. During the prewicrl week the E-v nad W becese coote5luld with On Wseds- vater. (This contasinstcc ws restored to within spe ficati)
day mnoring. 1-2-81U, a smain: steel nIpVl on Efe 1£4 9;Sven UnIO&Ver on This caused a loss of approxiwtall- X eaocws of £49 flvid.
"B" pump cracked.
gcwever. the pump The fluild and nipple were rep:aeed and "I" pup restartec.
Svera. atecPCS were made was imediately stopped fte tc scise and vibcatio- sas fo*co. :Ee system vas to troubleshoot the prob:= hot so def nite canse A= C: -9-n1 the lef: cperating satisfact'r'-y with one pUC;
.
leak which caamef £-E ':aid leak owt second E-H pump, "A". deweioped a sea ir to reto tar of the system. ^t 0541 =be operators begaz to t~aU che c= off Systet. At 062-_ wti* the unl: was being ea.-a:ec frw tani Vrste0,
tt.e E-
es vho--'
weamnc resulted the E-U System generated a pressure surge cc the Three factors r-L.d %-v rantri'rt:ed cc thf in the valves mozentaril- ape-ing.
- o . he cre- pressure surge. The turftie conro: was switchizg :- speec E1- oil pump cz sup;;.w T- 5;: ting z.lw final.
tors wre trying to star$ '5 The E-9 Srstem t beec :cc iza-d by water soments of the turbine s;dcn.
TIs caused a -- n;ary g sreas !loi- t- be sensed during the previous weeLk- T%. spike shows up oc s. tbrei sate f charts.
on at least 2 steam lines.
It % :-
The effect of this flow ipska Is described in Atta
.u to ag e *d t-areferre The failure of "A" pump *seal on tVc E-11 Syscem was
-is equent to these pui fe.+/-xres. :he uc:oader c'
vibration from "see pump.
5n iCs entiretr. .The pump Op" has been replaced ad pump "A" was replarad awc:sf actor' 7.
copl-tce system was resczred to service mnd is opcr=eimg
1 IIsm o -I 1111 INICOM I 1311011 'I51111P
E I I ; 0505010"NOWMW in 1XIMM 3 I
?tim-, St A? 0624 NMMS
was 0 o~esmcod to do repair work on Jwouay 2g. 198: at 054- a vuit absatdwn
1 7 0620 hours0.00718 days <br />0.172 hours <br />0.00103 weeks <br />2.3591e-4 months <br /> Tavg dropped below the on the tuzbl.m 14 S~atm. At ",proimzate overshoot duzring plant sbutdwnf.
low TOV .etpotint of 5401r Cut to at Snadverunft At 06..*t v~ct the vaic pwer Fe4 the generster output breakers were opemed turtbLoc E-F control discomc:WC the acit fr= th m~tam. At this tiae the the E-Hr Sstem switched te "ef aonT Idut cc gme55ure instabLttlItte is conr-: osyte tz txti-iCw Sovernar ?ralves .;citd t'i"n. A revicu ofb cte' event etex !,ow ini at least two ate&'
lndlz.es that thc sz,..;e ca*J'Cd o? tzdlcatet set:cimt for a time* 7erted ees ~than 2s vze lines to exceed Chu~ *tozz m he low Tavg d~icated t4gh sitom .. w to '3 eteag inee continedd vWt
7his a ea=L stoam Iscaticf vavG-. closu~re sp.jA. at.. a setle'M0- .arl'ler ;~efo:tat The 4ira.?aLt ce! :woes~avad1 te tte same as tV.e Ste~az fecw St st4!a..
t1s05 tI
tht the NSO.s requ,-.te a opike- It &as bees abserro! duriz( "redi~c signm,. Suraizo-, of sr .~y sec. to ct-use a-W. so none of the ?S~
fL'low low lava *Itnal. ('.be KS'Vs Were Menus ::
Closed, or the mczeg*T
closed £indiately by tte 0erator in order. to steb~ltZC US temperaturt.)
altz: trains 'A' and 'I'. Eoch of these traits cpe The S7 sips 1 is givldeC
- atcming cola? tWee inthosse -C
tAILS &seseraltelavs Inc-wI~d3 a "Czr.tanica:
manually reset. A s£gr1.8 WA6) uhic1h is used uo lock ft the 5S train unri
! mee. is reguired to Lnsure that al relays tdose '6nd dura10o greater. tb=1 o:
the archimg relays loce is. Usne* the ST Signal was 'Iess thr 25 *sc
"A op~erators waied:Ate~y the :Atch~flI rel~ay for tCm=i got fia:y engaged.
so they. -Paniaay started the :Vain rsotized that trai0 ~A" o WCt engaged and LnI1tL~td by trsaln "P*." 6
'A' equipment. CauessmaL t ssolation Phase A was the since RCS pressure was ftzlO0 -PSIC and St woer was a je-med late theosyste CM1 I I --- -- - --- - -
== EJMm sit I . , .I I - --- - -
EU.?-
smm off bead ofthe 5!POM*URO 61' 1 e glva u&aly rmetOat06
- Loce the SI £uin+/-LuLL gm WSSdUb5led Qpurtbul.
Ounc train "Ar was smagaa Li1+/-um the tl 5iqtm perfacrvid as expected, vIth the uceptLon of CV IsdIstZ= w,'.N FL-1&S (O05 Attacbmftt SO. 5). The actI3- tiara of the SI Syatm 4d4 t efl cphysical course of evets durtq the the trausleft. boveve? it 4LU mbcure :e cauS. of the KMS depresaurtzatLon (stuck pressuaazer spray valve). St rep.?s to the St logic or componerats are comSidete aecassury.
ta U- - -
mDRAFr- ATLUtME ND. 3 LzW LUE XU
vutcl gestrated a Phase A
At 0624 an St signal latched in the "B" train relaey containment isolation. As part of the Phase A _ontzint iSolatioC five letdwn Drir this time the relief valves closed (CVC-200A, B, C and CVC-204A. 5).
valve on the letdown line, CVC-RV-203; lifted. This us apparently ide to s&LLbtly fa"ter than the the Isolation valves, CVC-204A and CVC-2045. closinl c 2eakMe past one or orifice isolations, CVC-200A, CVC-200B and CrC-200C.
This then case he rressurier relLef more of the orifice isolatior. valves.
level) to ,5.= full.
tank level to increase from approximately '0: (noraL:
-- 2' to lift also The pressure transient while causing relief r&::
- his sae tinie, whet the caused the relief valve bellows tc rupture. A
This CVC-200A, a & C valves closed, a pressure su.rge was a:-::ed to C'C-200E.
- atay' y cen dzrfle valve is normally closed but had apparentl- r' te cm on Sl8. One plant operations. The valve position was las
- ver-'1 he ;ttve dispa:tnt possible cause for the vibratior at CVC-ZE-_ss..
in'tuced protem5 f'or charging p=ps. These pumps have a histor of vibraLtc:
which solutions are currently under develcren;t. CT-=DOE is also caped bu:
by the stripped threads the cap apparently was cot tightly securee as eviden ws *rlied to the CLC-200E
on the end of the pipe. When the pressure s&ge estimated at aproxintely cap the cap was blown off, causing a primary le"a dl.im.en amd qwntlty of water
100 1pm. This estimate was based on the pipe This leak was qui_ . e tc 5- Mwher.
discharged to the C: sup.
valves 460A
- B were shut by the operators. Appirez:T some leakage occurred The ;00 = leak ws restarted when past these air operated control valves.
de poin: and pressure letdown was re-established at 0635 causing consitae azd the leak rate again dropped to rise (.2.5 psi). At 0650 letdown was isolated cess tan 6000 galloas of primary to 5-7 pm. lased on the sup level indication coolant was discharged into the contaiment sz::.
Ve the lOC pr leak occurred
MUMM M. 3 (Contim")
it apparently coneed hat #4AIdIY LTG detector Ca tof LX
at 0(?4 the detector was locaed abmov te draft "LTe tM oN
" atC4 contaimmt.
deck. Since the opezators had indicatLOn of IS lInkae end
- tIt" In ts the countijnt* &a Individa using espiratory protection _a _nt Into coottaimt to LavostLsate. This Udivldual nftmed the Loags and Lsnat£ed the ource as the bstdown Lin but Was 1able CO UIntIft the exct Leak point because bLs air supply wed low. DurLM cbs Laspet@U s evldemce of fire vwa found.
dresed and a To prevent future occurrencs the CYC-2O0E pipe thrds vore cap errangeents nev ed zap installed. CVC-200 ard several other valvelpLp which could be eooed to the sam condition were inspecced and physically locked or verified secured in the closed position.
CaZ
mActM"W U. 4 a TS I) MUSMUATION
wran uAMxpllifd decr"se The "ain concern dWring the transient of 1-124L
psi& to 1620 psug ID Wtopo- in E pressure. The pressure dropped ften 2O0
steps were takes diauri the first bour of the transient Ustely mae hour. VA"
causig the deprseasqaatif. The ToeesuiZer (tsr)
to determine wbet v dwn- at the accOustic flow indicators safety valve were chocked by lookiag by of the vlves. No flow was indcated. The par rcVs were checked stres of the valves. Again. oo flow was looking at the pipe cmperature downstre55 shut.
checked to verify that they were Indicated. The tsr block valves vere they relief tank level and pressure were als checked to verify thac The Prr manual spray valves we then switched to were not increasing. The main tsr the The indication on the RTCS shoved control and Closed by the eperator.
this Iicatin ie oway of demand position, valve to be cloesed. bevee. mince cloeing operator tried to insure that the valves had closed by manua-ly the spray valve, Isolated to ass If the auxiliary them. The charging line was then flow RO "" and "VC were stopped so that CVC-31l. was leaking. Additionally.
began the main wry valves ASIA *& was not possible. Par pressure through bous) epray valve 4553 was positively ncrasiUg. Later that night (231S
Uentlfled as the leaking valve.
valve park- that the atm vs binding on the An inspection of the valve showd the One reason the binding problem was not identified earlier is that L34.
is pover operation. RZ pressure control spray valves do not move such during with the spray valve partially opered.
accomplished by varying the ?sr heaters the stm. The valve was then tested The valve was repaired by ubricatlng In addition, the electro-echanliCal four times to inswe proper operation.
ma discoverad to be*l htly off and therefore was poltoner garv setpoLit reset. -DtroT-
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cou- umr
- I3OLUATIOIE YALY IFAIK Mi- 248)
A contAiL.Ut LBolntLO . .ss At 0624 on 1-2981 a SI digal generated a Ph^a containt .; 'ation pert of this Lsolatlon the nSwly imtallh firx protection to shut. Vi-248 did not valve F?-2469 Fl-2'9.77-256, 7-25 vere sigled of failure Was a tripped sbut. The valve Wu then Manually sut. The cause operator. Subsequent reviw breaker hich Wul, not &llow power to the motor breaker was not set igh.
i6dcated that the trip point on the magnetic overload enouh to Insure proper operation.
alastion, however, the currect The breakers had been tested successfully upon I
and so if the trip point is tot demd of the valve motors can chane wvith tum and yet fail at a later tica.
Oet with enough magin the breaker cAn pass A test to ccmpeusate for the The setpoints on all four va1ves hve been r"edjusted ay future problem vith these above problm aad tested. This should correct
1 r1
£?Aft~ww No. G
S A 0? I5O CoIvtru WTMt W
0620 Alarm- Low Tavg Iezulasive Set
0620 Alarm - Lov Tavg 541.2 (setpotat La 543.0)
trtp)
0623 OU - Control 1.4 UA C Usertod (reactor Alan - 1.0 ?a 'I' W (Oc0e4 (St esLPa)
0634 Ala - Lov Tavs 532.7 (alanas Tavg)
0624 lifts)
0625 t= - 1.1 F1 DAltaf TaSk 75.2! (Valve CVC-203
0627 UTRX - K hop "3" BXI open (St reset)
gm -rZ Low I L St (SicW s: I l)
0705 I
WITS AJ _* - R ?,MP "I" 31KI MOWs
0705 _ . - "A" R. cowd
0 26 Alarm - RCL8 L rlow (4CP 'I" stopped)
C^27 Alarm - =CLC1 Flow CRC? "C" stopped)
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