ML20214L559
| ML20214L559 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 12/27/1985 |
| From: | Faulkenberry B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Eisenhut D, Heltemes C, Taylor J NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE), Office of Nuclear Reactor Regulation |
| References | |
| TAC-60462, NUDOCS 8705300061 | |
| Download: ML20214L559 (20) | |
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( Qp UNITED STATES i
' A NUCLEAR REGULATORY COMMISSION
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,I REGION V 0,,
f 1450 MARf A LANE, SulTE 210
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,6 WALNUT CRC CK. cal.lFORNIA 94596 DEc 2 /1985 MEMORANDUM FOR:
D. C. Eisenhut, Deputy Director, NRR C. J. Heltemes, Director, AE00 J. M. Taylor, Director, OIE FROM:
B. H. Faulkenberry, Deputy Regional Administrator
SUBJECT:
INVESTIGATION PLAN FOR RANCHO SECO AIT Attor:hed is my proposed plan for the Rancho Seco Augmented Investigation Team.
Please review and provide any suggested changes by COB 12/27/85, if oossible.
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d.
aulkenb'erry A
DeputyRegionalAdmidstratir
Enclosure:
As stated
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cc w/ enclosure:
W. J. Dircks.EDO Oj 8705300061 881227 PDR AOOCK 05000312 4
PDR L
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Augmented Investigation Team Plan 1.
Team Membership Al Chaffee, Branch Chief, Region V - Team Leader J. T. Beard - NRR (ICS and IIT Expertise)
R. Eaton - NRR (Human Factors and B&W Expertise Henry Bailey - IE Gordon Edison - NRR 2.
Tentative Schedule a) 12/27/85 - Team Arrives en Site b) 12/28/85 7:30 A.M. - Entrance Interview with Licensee Management 8:00 A.M. - Begin Investigation and Personnel Interviews c) 12/31/85 - Complete Investigation d)
Issuance of Report - 30 days from date of Exit Interview 3.
Team Objectives 4
m a)
Develop Description of Event b)
Develop Detailed Sequence of Events c)
Laentity Equipment rallures d)
Identify Human Factor Deficiencias e)
Determine Radiological Releases and Primary Coolant Radioactivity 4
Investigation Methodology a)
Conduct recorded interviews with licensee, contractor, and NRC personnel significantly involved in the event. Obtain information related to:
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I (1)
Description of even Q ' Sequence of events A
3)
Ind1 h ac. tion evaluations and observations throughout course of eve 14)
Adequacy of rocedures in responding to the event i
3 5)
Knowledge of equipment failuresand/orequipmentmalfunctions]
b) perform Records Reviews 1)
Operational data including computer printouts, recorder traces, and operational check lines and logs.
2)
Maintenance records of failed equipment.
3)
Documentation of unc and completion of plant and operating procedures during the event and recovery.
c)
Conduct review of applicable emergency, operating and maintenance procedures pertinent to the event and recovery to establish degree of adequacy and completeness y d)
Conduct independent visual inspections of plant equipment pertinent to event. including failed equipment, control boards and control instrumentation. Develop photographic records where appropriate.
e)
Obtain information related to exhaustion of SRO Q {C J tCW 1)
I.icensee management's Vvaluation for fitness for duty 2)
ReviewindividualsaphicationrecordsforSROlicense 3)
Obtain information related to treatment at hospital following event.
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5.
Event Evaluation Topres to be Addresed in hvestigation Report a.
Details regarding the ruct cause(s) of the event.
b.
Event chronology.
Functioning of safety systems as required by plant conditions.
c.
9)
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d.
Equipment failuren that cccurred during the event.
Connjutency of licensee actions with license requirements, approved e.
procedures, and the nature of the event, f.
Radiological consequences (onvite or offsite) and personnel exposure, if any.
g.
Verification that plant and system performance were within the limits of analyses described in the Final Safety Analysis Report (FSAR).
Currently Identified Issues h I h.r:::C&YkJh
- 6. __
6.
l n)
T.nes af power te ICS
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b)
Aux-feed system actuation
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Valve positions following loss of TCS b. d d 68 g IM
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c) d)
Main W pump performance on loss of ICS e)
Main W regulating and isolation valve performance upon reactor trip f)
Make-up pump failure g)
Radiation monitor (R15001) failure h)
Security /mafety interface during event l
1)
Rapid cooldown of primary coolant system i
k)
Operator performance 1)
Possibic damage to RC pump seals m)
Effects of previous corrective action in response to Bulletin 79-27 and other pertinent NRC correspondence 6 O&
0tN 'Y Y YM h W CCC c 4
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M' Prel.m ea o u u,,3,, 6< e 4 4<J CHRONOLOGICAL SEQUENCE OF EVENTS c,,,,,,,,,, r i u g 9 / p.s S ' C0 p ~ P > T~
b~
12-26-85 Tet td % %
Inital Conditions EcchM Wg thit operatirg at steady state pNer of 76%, 710 MW(e)
!rU r >ted centrol system in full autcoatic
~
Bai' ; CcTputer out of service (one of the plant's two main ccmputer systems in tne control room) fransient Initiator Time Source
_ Event /Acticn 04:13:07 Loss of ICS power.
All lights on the ICS stations ge out.
All demands fail to 507..
"Less of ICS Po..er annunciator alarns.
- 7. :m 'iesxnse/ Operator Actions Prior to Trip 04 '3:43 Feedpumps slew down and feedvcives start to cicse due to decrease in ICS demand signal. FeedwoAe-hw ko A CT5G's dev ectses RCS pressure begins to increase.
C1 13:51 Atmospheric Oump Val.'es (ADV's), TSV 5 drift cpen.
There is only cne ADV in service por side.
Four have been isolated for the last several cycles due to overcapacity of ICS steam dunp capability.
06: 14: 01 AFW Pump P-319 autostarts on main feedpuna low discharge pressurc
$50 psig.
The failure of ICS has caused demand to decrease far cc: :
on both feedpumps to pick up the pressure switches.
At this point tnere is no feed. vater to the steam generators.
04:
- 1. '.1 Reactor Trip on high RCS pressure.
The operators i=ediately carr;. :et the actions of E.01, the Reactor Trip Procedure.
System Respcnse/ Operator Actions price to SFAS initiation.
C4:1'.00 aft.' dual drive purp ?-318 autcstarts on lov, feedpuno dischargc prese 'e (850 psig).
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System Response / Operator Actions Prior to SFAS Initiation 04:14:11 Loss of ICS power causes AFW air-supplied control valves to drift half open.
04:14:25 Operators performing procedure E.02, vital SSV, pressurizer level decreasing, fully opened A inject valve for more makeup addition to RCS.
04:14:30 Operaters sent to close TBV's, ADV's, and AFW flow valves.
- 04:14:48 Makeup tank level decreasing rapidly.
Opened SWST sucticn valve en A side.
04:15:04 Started B HDI pump to increase makeup addition, t
04:16:02 A & B niin feedvater flow reccrders are indicating half-scale.
Oper:*
oelieves MFW is not decreasing as expected and trips A nain feedwater puTos per procedure.
04:16:04 Geor 9er trips B main feedwater pump per procedure.
04: 15:57 FCS 3ure has decreased to lo00 psig. Pressurizer level is 20 inches.
SFAS automatically initiates.
8, C and 0 HPI injection valves travel to pre-throttled position. A injection valve travels
'ron full open position to pre-throttled position.
Selected SFAS equipment, including notor-driven AFW pump P-319, t'ips and block r
loading of SFAS ecuipment begins.
AFW SFAS valves travel full open.
A S B DMR pumps autostart.
Diesel generators autosta'rt but do not I
clese into vital busses.There has been no loss of power to the vital busses.
l hdem 12gmse[Opervdor du.(o ll e m 3 SFAS (octwnou 04:16:59 A HPI pump autostarts from SFAS signal.
- 04:17:10 Operator closes AFW SFAS valves.
It is recogr.ized these valves will result in a severe overcooling if left open.
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3 Folle wm SystemResponse/OperatorAc_tionsP"ic-tkSFAS___ Initiation h[
04:17:15 A & 8 CR/TSC ESS HVAC units start from SFAS signal.
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04:17:27 Motor driven AFW pump P-319 is loaded back on its vital bus and immediately restarts.
The dual-drive AFW pump has been running continuously since it started E few morrents af ter the loss of ICS power.
04:19:15 Operator secured A CR/TSC essential HVAC to reduce ambient noise level.
04:20:00 PRSZR level offstale low.
f 04:20:20 OTSG pressures have decreased to 500 psig.
At this pressure the running condensate pump has enough head to begin to feed the OTSG's.
The main and startup feedwater valves have failed partially open due to loss of ICS pcwer.
This pump adds approximately 1000 gpm feedwater to the OTSG for a couple of minutes.
04: 22:50 OTSG pressures have decreased to 435 psig. Main steamline failure l
logic closes startup and main feed valves.
Flcw from condensate t
c ap is stocoed.
04:23:00 Af.V's and TBV's isolated.
04: 23: 10 2 AFW control valve partially closed Operator thought he had completely closad it.
Feedflow through it had decreased by 60%.
04:24:30 A & 8 CR/TSC ESS HVAC units start from SFAS signal.
Iyudw c
- 04. 25:30 Unisolated HPI pump SFAS recirc valves. h d el vo m 04:26: 15 CR/TSC ESS HVAC Train B is secured.
Op'erator notes that signal to J
i start it in the hi temcerature/high rad level mode is present.
04:26:22 A AFW valve closed. Operator believes it is only 80% closed.
Leaves to find cheater.
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f Fohm System Response / Operator Actions f-ri SFAS Initiation 04:26:47 Started to throttle HPI injection valves to decrease rapid increase of subcooling margin.
SCM now 155'F.
pRSZR level 30" increasing rapidly.
04:27:30 Pressurizer level back on scale and increasing.
Subcooling margin is 160*F.
04:28:00 Makeup tank level offscale high.
Tripped RCP C.
04:28:59 Shutdown A HPI pump.
Subccoling margin and pressurizer level still increasing.
04:29:40 Operator uses cheater on A AFW valve.
Manual operator is damaged.
Valve flies back open.
Operatar calls Control Room and is told to close manual isclation valve, WS-063.
04:29:45 C & D HPI inject valves shut.
Xeducing flow to stop the increase of l
of subcooling margin.
SCM=190*F 04:3G:30 Opened pressaizer spray and started RCS depressurization to below the PTS curve.
04:33:20 Operator 8 arrives at B AFW valve and finds it partially open.
He closes it all the way.
Feedwa er to the B 0T50 has been stopped.
04: 33:40 A steam generator is full up to the top of the steam shroud and begins to spill water into the steam annulus.
04:36:00 Operator attempts to close FWS-063 but handwheel vill not move, even with cheater.
04:39:00 RCS subcooling margin reaches ;eak of 201*F and begins to decline.
04:40:00 ICS p0wer is restored. All ICS valves reinitialize full cpen.
Operators place valves ir automatic control but valve demand does not decrease.
Valve contn 1 :tsticns are placed back in manual and n' 'es driven clcsed.
1 Flow to both OTSG's has ceased.
EC5 begins to he3 tup.
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RAtw m3 System Response /Opelet.or Actions P m.do SFAS Initiation 04:41:00 Operator calls Control room and informs them that FWS-036 is stuck
.open.
Told to reopen AFW valves, told other operators to unisolate TBV's.
04:41:10 A steam generator level goes below steam shroud.
Spillage into steam annulus stops.
04:42:42 Shutdown B HPI pump. Makeup pump cotinuing to run.
04:42:56 Clcsed A & B HPI injection valves.
No makeup to RCS except RCP seal water.
04:43:50 Operator noted loss of RCP seal flow.
04:43:54 B HPI pump restarted.
04: 50:00 Closed SFV-25003, BWW A54 S MW M" v-P 04: 50:19 B HPI shutdown.
04: 50:30 Operator again notices loss of seal flow. Restarts B HPI pump.
05:00:00 Operator in Control Room hears loud noise.
Looks down at makeuo pump ampmeter and notes it is reading about 1/3 of normal running current.
He realizes makeup pump nas been destroyed due to lack of suction.
05:00: 10 Operator trips makeup pump and opens makeup tank outlet valve.
Water spills out of the makeup puTps seals onto the pump room floor, The valve is reclosed.
Approximately 450 gallons is spilled.
1 05:01:00 SR0 collapses ir ' mt of centrol panel.
l 05:06:00 Ambulance is calle; ror SRO.
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-r-RANCHO SECO TRANSIENT 12-26-85 PRELIi11tiARY SEQUENCE OF EVENTS O
04:14:49
- Loss of ICS Power 04:15:03
- Reactor Trip on High Pressure 04: 15:08
- Manually tripped both main feedpumps 04: 17:57
. SFAS initiation at 1600 psig, Automatic 04:22
- Lowest RCS pressure = 1047 psig.
RCS Temperature = 456'F 04:25
+ Isolation of Atmospheric Dump and Turbine Bypass Valves completed
= Secured "A" HP! Pump Declared Unusual Event e stopped "C" RCP 0430 a
0435
. Makeup Tank level high; closed SFV-25003 ("A" loop BWST Suction Valve)
- Started depressurizing RCS
'0440
0 4'11 Regained ICS Power 0444 ~
' Secured ":5" HPI Pump 0445 Losing RCP Seal Injection, restarted "B" HPI Pump; manually tripped
~
Makeup Pump.
0450 Received Auxiliary Building Stack Rad Monitor High Alarm due to
+
water released fro.T demaged Makeup Pump 0500-Terminated RCS pressure decrease; started three-hour hold at RCS pressure 715 psig,. Temperature 433*F 0505 Makeup Pump isolated
+
0507 e Ambulance called for SRO, Exhaustion Stopped "A" RCP 0530 0547 Reactor Bldg. Rad Monitor (R15001 A. and 8)
+
0614
- Momentary loss of ICS power 0700 SRO released,from hospital, Satisfactory condition Terminated Unusual Event 0841 NOTE:
Minimum subcooling margin was not lost.,
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Sys t_e Response /Operatcr Actions Prior to SFAS Initiation 04:14:11.
Loss of ICS power causes AFW air-supplied control valves to drift half open.
04:14:25 Operators performing procedure E.02, vital SSV, pressurizer level
~
decreasing, fully opened A inject valve for more makeup addition to RCS.
04:14:30 Operators sent to close TBV's, ADV's, and AFW flow valves.
- 04: 14:48 Makeup tank level decreasing rapidly.
Opened 3WST suction valve on A side.
04: 15:04 Started B HPI purp to increase makeup addition.
04:16:02 A & B main _feedwater flow recceders are indicating half-scale.
Operator believes MFW is not cecreasing as expected and trips A main feedwater pur.ps per procedure.
04:16:04 Operator trips B main feedwater puma per procedure, j
04:16:57 RCS pressure has decreased to 1600 osig.
Pressurizer level is 20 in:hes.
SFAS automatically initiates.
B, C and 0 HPI injectico valves travel to pre-throttled position. A injection valve travels from full open position to pre-throttled position.
Selected
- ^ %
equipment, including trotor-driven AFil pur's P-319, t-ips and clark i
loading of SFAS equipment begins.
AFW SFAS valves travel full open.
A & B DHR pumps autostart.
Diesel generators autostart ' ut ce nct c
cicse into vital busses.There has been no loss of pher to the ',:tal busses.
$gs6 Mye3, c /Operrdev Acd % (oUe~m3 $FA5 WT ug -
04:16:59 A HPI pump autostarts from SFAS signal.
j
- 04:17:10 Operator closes AFW SFAS valves.
It is recognized these valves will result in a severe overcooling if left open.
j,
r RANCHO SECO TRANSIENT 12-26-85 PRELIrlINARY SEQUINCE OF EVENTS 04:14:49 Loss of ICS Power 04: 15:03
- Reactor Trip on High Pressure 04: 15:08
- Manually tripped both main feedpumps 04: 17:57
- SFAS initiation at IC00 psig, Automatic 04:22
- Lowast RCS pressure = 1047 psig.
RCS Temperature = 456*F 04: 25 Isolation of Atmospheric Dump and Turbine Sypass Valves completed
- Secured "A" HPI Pump 0430
- Declcred Unusual Event e stopped "C" RCP 0435
- Makeup Tank level high; closed 5FV-25003 ("A" Loop BWST Suction Valve)
- Started depressurizing RCS 0440
- Lowect RCS Temperature = 386*F.
RCS Pressure = 1413 psfo, 0141
- Regained ICS Power 0444
- Secured "8" HPI Pump Lesing RCP Scal Injer. tion, restarted "S", HPI Pump; nane :lly ?.*ipped 0445 Makeup Pump.
r eanved Auxiliary Duilding Stack Rad Monitor Hign Alar.- due to 0450 water released fccm car:gr.d Makeup Pump 0500
- Terminated RCS presture decreate; started three-hcur bold at RCS pressure 716 psig, Te.Tperature 433*F 0505
- Makeup Pump isolated 0507 Arcular.ce called for SRO, Exhaustion e
0530
+ Stopped "A" RCP 0547
- Reactor Sidg. Rad Monitor (R15001 A and B) l 0614
- Mcmentary loss of ICS power
'0700
- SR0 released from hospital, Satisfactory condition 0841
- Terminated Unusual Event l
NOTE:
Minimum subccoling r$argin was not lo it.,
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12/30/85 y-fu.V he 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br />
V 0 a ycD SEOUENCE OF EVENTS M
Following developed from IDADS print out, Alarm Typer and Operator interview.
Time adjusted to IDADS print out time.
minute shead of IDADS time.
Control Rocm clock was found to be about (1)
Bailey computer was out of service.
(Consecuently, the Bailey post-trip review, Sailey Alarms, and Bailey IDAD points were not available.)
__ TIME DESCRIPTION OF EVENT OATA SOURCE 04:13:47
" Loss of ICS Power" Annun:iator Alarms.
IDADS Print out.
Upon a loss of ICS power all ICS demands go to midscale, corresponding to zero volts.
(The ICS works on 10 volt scale, zero volts being 50% demanc.) The startup and main FW valves closed to 50% demand because of this decrease in demand signal.
The MfW pump speeds were reduced to low speed. This excected response of the feedwater system is illustrated by attached graphs of main feed-water pumps speed versus time, main feed pump discharge pressure versus time and main feed-water flow rates, all of which indicate a oe-crease just prior to reactor tric. With the plant initially at abcut 76% full power, this reduction in feeawater ficw is expected to 1
increase RCS pressure.
The loss of ICS power also sends a demand to the Bailey.UW control valves and ADVs and 1
TBVs to cren to 50% cemand.
Tne effect of the ADVs and TSVs ocening to aoout $0% is in-dicateo on the attached plot of high resolution of OTSG pressure versus time.
This IDADS plot clearly shows SG pressure decreasing prior to the reactor trip.
04:13: 7 Operators notice MFW flow decreasing rapidly. Also Operator Personal noticed RCS pressure increasing. Operators opened Stateaent oressurizer spray valve in an attempt to stop RCS t
oressure increase, i
s Due to the overheating of the RCS by the re-cuction in MFW flow, the actuation of pres.
surizer spray is not sufficient to reverse RCS pressure, as shown on the IDADS print out of RCS pressure.
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I TIME.
DESCRIPTION OF EVENT DATA SOUP.CI 04:14:01 The low main feedwater pump discharge pressure 10 ADS Print out of less than 850 psig automatically started the electric driven AFW pump, P-319.
04:14:03 Reacto-trip en high RCS pressure. The turbine IDADS Print out trip is also initiated by the reactor trip.
00-erator closes pressurizer spray valve.
04:14:06 AFW dual crive pump, P-318, autostarts en low feed-10A05 Print out pump discharge pressure (850 psig).
AFW pump, P-318, was steam driven throughout this transient.
03 : '. 4 : ?
Irmediately upon reactor trio, many fire alarms, Operater Parsonal TSC spray actuation alarm, seismic trouble alarm, Statement and SFP temperature hign alarms were received.
The operators performed the actions of the Emergency Procedure section E.01.
This in-cluded reducing letdown flow.
Operators then proceeced with Emergency Pro-cedures section E.02.
04:14:11 AFW flow began to coth OTSGs.
10A05 Print out 04:14:25 Operators perfcraing proce::ure E.02, Vital System Operator Personal Verification due to pressurizer level de:reasing, Statement /
fully opened "A" inject valve for more maseup IDADS Print cut addition to RCS.
04:14:30 Operators sent to close TSVs, ADVs, and AFW flow valves.
Operator Personal Statement 04:14:48 Makeup tank level decreasing rapidly. Operators Operator Personal ooened SWST suction valve on A side (SFV-25003).
Statement 04:15:04 Operators started S HPI pump to increase reactor IDA05 Print out 1
coolant inventory from BWST.
l 04:16:02 Operators tripped both MFW pumps.
10A05 Print out/
Operator Perscnal The operators recognized the beginning of Statement an overcooling transient due to the failed open startup and main FW valves, the half open TBVs and ADVS, along with main feed-pump speed remaining at around 2500 RPM.
The c erators tripped MFW pumps per step 4.0 of Emergency Procedures section E.02.
The operators may have also noticed the feedwater flow indication remaining high on the control room strip charts at about 3.5 million pounds per hour. However, this FW flow indicaticn is temperature compensated by the ICS and it had also failed to midscale.
Tne actual main feed-
I l
ImE DESCRIOTION OF EVENT DATA SOURCE water flow rate indicated by the IDA05 print out dacreased to zero uoon reactor trio and had not begun increasing again cefore the reactor operators tripped the tiFW pumos.
Tne actua' main feedwater flow rate remained at zero due to the increased pressure in both SGs and the low speed de-cand to ooth MFW pumps.
-At about this time, two (2) of the operators verified that AFW flow was high indicating greater than 800 gom to each SG. This is verified by the IDxDS print cut of aux, feed-water flow rates which show that AFW flow to both steam generators was greater than 1000 gpm at the time of the PfW trip.
04:16 :1 The cperator secured pegging steam.
Operator Personal Statement 04:16:57 RCS pressure nas cecreased to 1600 ps13 Pres-IDADS Print out surizer level is 20 inches. SFAS automatically initiates.
3, C and D HPI irjection valves tra-vel to pre-throttled position. Selected SFAS equipment, including motor-driven AFW pump P-319, trips and block loacing of SFAS equipment begins.
AFW SFAS valves travel full open. A & B DHR pumps autostart. Diesel generators autostart but do not close into vital busses as there nas oeen no less of power to the vital busses.
04:16:59 A-HPI pump autostarts from SFAS signal.
10 ADS Print out 04:17:10?
Operator closed AFW SFAS valves wnich were-fully Operator Persanal ocenea by tne SFAS actuation.
Statement /
These valves will result in a severe over-IDADS Print cut cooli.g if lef t open or untnrottled. Closure of these AFW SFAS valves is shown on the aux. feedwater flow rate versus time IDADS plot which is attached. Within about 10 seconds after the first AFW flow rate de-crease, due to SFAS load snedding of the motor-driven AFW pump, a second smaller decrease is indicated which is attributed to closing of the AFW SFAS valves.
t 04:17:15 A L B CR/TSC Essential HVAC units start from the SFAS signal.
IDADS Print cut 04:17:27 Motor-driven AFW oump, P-319 is loaded back on its IDADS Print out vital c' us and imediately restarts. The dual drive AFW pumo has been running continusously and powered by steam since it started a few mcments after the loss of ICS power due to decreasing MFW discharge pressure of less tnan 850 psig.
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l TIME DESCRIPTIO!! 0F EVEtiT DATA SOURCE The restart of the motor crive AFW punp is con-firmed by the plot of aux. feedwater flow rate versus time which is attached.
This plot sno.vs the "A" aux. feedwater flow pegging high, shortly after the ourp is restarted, at 1300 gpm and the "B" aux feeowater flow continues to increase to about 1250 gpm.
04:19:15 Operators secured A-CR/TSC essential HVAC.
IDADS Print out 04:20:00 Pressurizer level offscale low. Subcooling margin
! DADS Print out is S5'F and increasing.
The IDADS pressurizer level point is non tem-erature compensated.
However, the control room strip chart of pressurizer level does show temoerature cc:noensated level. A comparison of these two show that the IDADS pressurizer level correlates very closely with the control room strip chart once pressurizer level re-turns on scale. By this time, temperature in tne RCS has fallen to the point wnere tempera-ture compensation is rot significant for accut-ate pressurizer level.
?
Operater sent technician to look at the ICS power.
The tecnnician reported that all four ICS cower supplies were de-energized.
The ABT had not transferred and was still en the "C" bus, and tne "J" bus power was still avail-acle.
It was later oetermined that the ICS "J" aus loads had earlier oeen connected to the "F" power bus.
The "F" cower bus also supplies power to the TSC Fire System (wnich alarmec uoan reactor trip) and portions of tne security lighting (which was indicated oy security personnel tc be mementarily out about tne time of reactor trip).
04:20:20 SG pressures have decreased to 500 psig.
10 ADS Print out At this cressure the ranning condensate pumps began to supply FW to the SGs. This is in-dicated on the attached main feeQwater flow versus time IDADS plot.
This added approx-inately 10C0 gpm feecwiter to eacn SG for a couple of minutes.
0h22:50 SG pressures have cecreased to 435 psig.
IDADS Print out Main stean line failure logic closes the startup and nain feed valves. FW flow from condensate pumps is stopped.
04:23 CVs and TBVs isolatea by operators.
Doerater Personal Statement
f.
_ TIFE DESC9IPTION OF EVENT DATA SOURCE _
04:23:10 "S" AFW control valve par:ially closec by coerator IDADS Drint out/
ai.
Operator Persona?
Statement The coerator tnouca: 1e had completely closen tne valve at this point.
Feed-water flow to the B SG, however has decreased or about 60%.
04:25:30 Ocerator unisolated HP! oump SFAS recirc valves.
IDADS Print out Opening recirc path to Makeup tank.
04:25:15 CR/TSC ESS HVAC train B is securec.
Operator notes that signal to start it in the high temperature /high rad level mode was present.
04:26:?
Operator attempts to close A-AFW control valve.
IDADS Print out 04:26:22 A-AFW valve closed. Ooerator believes it is Follow up only 80% closed.
!. eaves to locate valve wrench.
Interviews 04:25:47 Pressuri::er level back on scale and increasing.
IDA35 Print out Succcoling margin is 170 F.
Started to tnrottle HPI injection valves to decrease rapid increase of subccoling margin.
04:28:00 Makevo Tan < 1evel cffscale hico.
ICA05 Prmt 1 t 04: 25:00 Manually stcpoed RCP-C per core lift recuirenents.
! DADS Print ou:
04:29:40 Operator uses valve wrencrt on A AFW valve. Manual Operatcr Personal operator is danaced. Vahe flies back coer..
Suterent Operator calls Cen:rol ;c m and is toic te
- lose manual isolatico valve, FWS-053.
04:29:45 Ocer nor closes C & D bP: inject valves.
Reducing
! DADS Print out flow *o stcp tne increase of succociing margin.
SC.9 190'F.
04:30 Declarec Unusual Event.
Notified State anc County Operator Perscnal Agencies.
Statement 04:33:30 Started depressurizing RCS to return to condition Operator Perscnal outside PTS region using normal pressurizer spray.
Statement & RC Pressure Plot 04:33:20 Operatcr #2 arrives at S AFW valve end finds it Doerator Dersonal cartially coen. He closes it all the way.
Feed-Statement /
water to the B OTSG has been stopped.
10A05 Print out i
l
- - - - - - - - - - - - - - - - - - - - - - ^ - - ^
j 1
-5 TIME DESCRIPTIO!i 0F EVEriT CATA SOURCE 04:33:40 A-0TSG is full up to the too of the steam IDADS Print out shroud and cegins to spill water into the steam annulus.
04:35 M/U Tank level was high so closed SFV-25003; Operator Personal "A" Loop BWST Suction Valve (which had been Statement opened earlier).
This isolated the suction of the M/U pump and the A-HPI pump and the "A" Decay Heat pump.
00:36 Operator has attempted to close FWS-063 but it Operator Personal will not cove, even with valve wrench.
Statement 04:39:00 RCS subccoling margin reacnes peak of 201'F and oegins to decline.
IDADS Print out 04:40 ICS cower restored. Operators closed breakers Operators Personal Si and 52 in ICS cabinet 3.
Statement /
IDADS Print out Ooerators regained control of ADVs, TBVs and and AFW valves (Bailey).
All these valves were immediately closed manually. All AFW flow to botn OTSGs has ceased. RCS begins to heat up.
Lowest RCS temperature of 386*F was reached and at this time RC pres-sure is (1413 psig) being reduced to achieve conditions outside the PTS region.
04:41:00 Oceratar calls tontrol reon anc informs tnem tnat Operator Perscnal FW5-063 is stuck ooen.
Iold to reopen AFW valves, Statenent told other coerators to unisolate TBVs.
04:41:10 4-0T33 level goes below steam shroud.
IDADS Print au:
04:42:42 Shutdown 5-HP! puro. M/U aurp ccntinuing to run.
IDADS Print cut C4:42:56 Cicsed A & B HPI inje: tion valves. lic makeup to ICADS Print out RCS except RCP seal water.
\\
C4:43:50 Operator noted Icss of RCP seal injection fio*.
Operator Personal Statement 04:43:64 B-HPI pump restarted.
10 ADS Print cut 04:50:19 B-HPI pump shutcoon.
IDADS Print cut 04: 50:30 Ooerater again notices loss of seal ficw.
Re-Doerator Personal starts B-HPI pump.
itatement 04:52 SRO collapses in front of control panel.
Operator Perscnal Statement i
1 o
, T'yE DESCRIDTION OF _E'!ENT CATA SOURCE 05:00 Operator in Control Room hears louc noise. Looks Operator Ders:nal coun at makeup cump ammeter and notes it is read-Statenent ing &Dout 1/3 of normal running turrent. He realizes makeus pump has been damagea due to inck of suction.
05:00:10 Operator trips makeuo putp and coens nakeup tank Operator Personal outlet valve. Water spills out of the makeuo Statement pump seals onto the pumo room floor. The valve is reclosed. Approximately 450 gallons is spilled.
05:05 Crossed cut o r Interim Brittle Fracture Limit, 3 Operator Personal hour soak is in progress.
Statement /
ICADS Print out 05:05 Amoulance is called for SRO.
Operator Personal Statement 05:09 Both AFW punos are manually secured while OTSG IDADS Print out is reduced to restablish normal main feednater.
05:27 Makeuo pump isolated.
Operator Pe sonal Statement 05:29:04 Goerators stopoed the "A" RC pump.
10A05 Print out 05:33 Smoke detettor locks out Rad Waste Area Exhaust Operatcr Personal Fans. Ocerator receatedly tries to reset these Statement breakers.
Late 'ock out clears and exnaast fans are started.
05:40 Main steam line failure icgic is inhibited.
inis Operator Persenal oermits the normal feed flow pathway to oc used.
Statement 05:05:00 Bypassec Safety Features.
Doerator Personal Statement 05: 1' Mcmentary ICS cower supply alarn.
Ooerator Persona; Statement 05:14 Loss of 1;S cower. Operattrs immediately reset Operator Personal breakers $1 and 52 in cabinet 3 to restore ICS Statement cower.
07:00 SRO released fcct hcspital.
Operatcr Per:enal Statement 08:21 Terrinate Urusual Event.
Emergency Coordin-ated Log L