ML19343D615
| ML19343D615 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/23/1981 |
| From: | Reinaldo Rodriguez, Rodriquez R SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Padovan M NRC |
| References | |
| NUDOCS 8105050558 | |
| Download: ML19343D615 (9) | |
Text
.
e esuuo SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 s street. Box 15830, sacramento, California 95813; (916) 452 3211 April 23,1981 f ',., '/ l, 50-3t*
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MARK PAD 0 VAN liAIL STOP 330
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s NUCLEAD REGULATORY COMMISSION WASHINb.JN DC 20555 Attached to this letter is a compilation of the various reactor shut-downs that have occurred at Rancho Seco over the years. This information is being provided to you, as the result of your unofficial request for such data, to be used in an analysis prrc; ram within the Comission.
Should you have any questions on the information provided, please refer mt Dan Whitney, of my ?.taff, at extension 220.
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4 PLNIT RMCIIO SEco RATED POWER 2772 im h CrffEPfl.4. TEPATIfXI 4-ts.-25_
BREIF DESCRIPTION OF SCRAll SEQUENC'E PRIOR TO SCRAM nrAc m n OUTAGE DATE sTxtuS.
T!HE TYPE OF SCRAM INCLUDE'THE ACTUAL INITIATOR OF.
MODE POWER AFTER (HR)
THE SEQUENCE SCRAM Vital p wr.r l us Inverter "C" t ripped ile-Stea'dy cuaninp, Mwate flow anil t ripping 12-26-74 39.5%
llot 17 hrs.
RPS Trip, hlRh RCS reactair f rom high itCS pressure. Caissed by State 4:16 Sinit down pressure component failure within vital power bus inve rte r "C".
Vital power bus inve rt. "C'* t ripped dec reas-ing P.li. vlow and t ripping Rx f rom hinie RCS 40%
llot RPS Trip,high RCS, Press. cauned by comp'onent fall. within vital Steady 12-28-74 3
power hua in ve rt. "C alt.o nroblem may he 3:50 Shutdown 21 hrs.
pressure at tributed to had elect rica1 connections.
Power Af te r repai rn were made on ".1" inverte r (which nowers ICS "Y" power uupply a reactor Steady non-nue. inst. power supply?, power was RPS' Tr.ip on varf,,1hl.e n it ched too slowly back to ".l ', musmentart iv 12 ~11-74 State 40%
Ilot 2:15 Power F.P.
Shutdown 6.5 hrs pressure & temperature paralleIing redundant
"!" hun wit h
".l" in-verter which caused ".1" fuae to blow, trio-ping plant on variable press.ure an I t empera-ture.
i The t urbine-gene rator t ripped.chen an ove r-1 t
sneed trip relay was energined by eit her Steady tite Scot or EilC systeru. Subacquently, the 2-12-75 State 923 llo t 5.0 hrs RFS Trip,liigh RCS reactor t ripped on high reactor coolant ava-2:23 Pcwer
- .P.
Shutdbwn Pressure tem pressure.
The reactor tripped on low pressure while D
Procedure 75%
llo't performing test procedure TP 800--42, load Test "N"
I"II E "
Z T.P.800-F.P.
Shutdown 20.0 hrs RPS Trip, low pressure 42 The reactor tripped on power / Imbalance /flos O,
' Pseudo due to an,lucorrect control rod management my Cj Design Approach-llot RPS mg pWW, schedule causinR* an excessive negative in-2-23-75 Transient ed 87%
Shutdown 6.0 hrs.
1766 jg halance.
Test STP-F.P.
y.
a b e==s f17Q l
1 F""
S 4
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4 RATED POWER 2772 INTh C0lVERCI AL OPERATION.4-18-75 Pl.A!!T RANCil0 SEco PRIOR TO SCRAM ncncmn OUTAGE CRElf DESCRIPTION OF SCRIJi SIAVE! ICE - -
DATE STATUS Title TYPE OF SCRAM IllCLUDE Tile ACTUAL IllITIATOR Of.-
MODE POWER AFTER (llR)
Tile SEQUEllCE SenAM
~~
Increasint The Reactor was being held at 82% F.P. while Reactor wat ing runnt burn out to per tech.
3-18-75 llot spe. requirements. The on-shift crew debor-15:16 82%
Shut-2.0 hrs.
RPS Trip, power /imbal-
"I" "" "" ""
II" "E F.P.
down ance/Gow llot borating. Upon observing the reactor response S ady Shutdown horation was commenced. Ilowever, due to the slow response of the makeup system, the reactor tripped on power / imbalance / flow.
Design Reactor tripped on power / imbalance / flow as Transient power was being increased from 40% to 92%
8 RPS Trip, power /imbol-F.P. during performance of STP-029, pseudo 3-13-75 ut wn 18: 30 ance/ flow design transient" test., caused by CPA mgat.
rs.
F.P.
sched. error. 'overinsertine croun 6/7.
Reactor was tripped manually as' resguired by 3-22-75 TP 800-E" Cold 585 Manual shutdown, TP 800-E
" "E" """,,P'*~
I commercialof"it Shutdown
. hrs.
40 un inspection.
Dia in Mai with abnarmal OTSG 1evel and RCS Tave The Feedsater controls were placed into As to -
4-14-75 rurb Byps kPS Trip, high RC pres,
20:55 Atmo Dmps 15.1%
Ilot ICS reduced feedwater flow when placed in 12 hrs.
sure 2355 psig
& st up Shutdo.wn Automatic.
VIs in Auto Reactor tripped on hf.ch RCS pressure wher.
Steady er fan dudng electrical u. T.
EE"E" Trip high RC 4-lb-75 35%
Hot 8 hrs.
Pwe r pressure 17:19 Shutdown Reactor tripped on power / imbalance / flow Sta 82%
RPS Trip power /imbal-
""I
- I"*'f""I"E. powr for 0%-87% F.P. slw "E
.4-22-75 Shutdown 11 hrs.
response of boron p
fg g 6:44
4
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PLo.ilT RATED POWER 2772 ftITh C0f tERCIAL OPERATION 4,-18-75 i RANClio SECO PRIOR TO SCRAM ~
nrncan OUTAGE BREIF DESCRIPTION OF SCRAM SEQUEiKF. -
DATE STATUS TIME TYPE OF SCRAM IllCLUDE THE ACTUAL IHITIATOR OF.
MODE POWER AFTER (HR)
THE SEQUENCE,
SCRAM Rx, Steani EllC Bus power supply is to be at 15.0 Cen. In volts. Power supply was set slightly higher Auto.
to maintain 15.0 volts in the Bus. Not re-6-M Turbine 37%
Hot I hr.
Reactor did not trip.
alizing this, a technician saw almost 16.0 15:50 EllC in Standby at power supply and turned down to 15.0 v.,
manual causing a lower voltage in Bus and a trip resulting f rom closure of the governot valves.
Reactor t rip, high pressure, RCS. l.oss of feedwater for a few seconds while operator
"*"E
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45 ICS S tdown 6 hrs.
Reactor Trip, high P"",E g
i manual pressure, RCS.
I-Failure in CRD System group 7. t ripped 3-1-76 92.5%
llot RPS Trip, low RC pres-reactor due to low RC pressure.
I 11:13 Auto.
Steady Shutdown 13 hrs.
sure.
State t
Reactor tr,lp occurred on high reactor cool-Man.except ant pri'ss. due to a loss of feed flow. Main l 10-10-76 g
ump A" was out of service. Main W Pump i
Byps 6 RPS Trip, liigh RC 00: 36 Shutdown 4 hrs.
"B" was being controlled in manual when it g,
suddenly reduced R.P.M.
s.
ne h Diamo.M Reactor trip on high pressures due to loss 10-10-76 RPS Trip,'high RC-of feedwater pump s38% reactor power.
g i
38%
llot 11 hrs.
18 pressure.
Auto.
Shutdowa The Scot system was transferred from test tu normal mode. A tyrbine-generator trip re-11-13-76 Full 72%
su y means co s Dump valves on the llot
.4 hrs.
RPS Channel A trip on 16:14 Auto.
Steady Turbine control valves opening. Atmos. Dump Standby power / pumps.
valves and Turbine Bypass valves opened. The State Reactor Did Not Trip.
Reactor remained on line, though RPS channel A tripped on power / pumps.
e ww
4 PIEIT u ncno SFco RATED POWER 2772 INTh C0ffERCI AL OPERATION 4-18-7.jL.
PRIOR TO SCRAM ncncmn OUTAGE BREIF DESCRIPTION OF SCRM SECL"it!CE -
DATE sTvroS TIME TYPE OF SCRAM INCLUDE THE ACTUAL INITIAT0Tt CF.
MODE POWEn ArTER,
(HR)
THE SEQUENCE SCRAM y
Both, main holler feedpumps tripped and the' resulting loss of feedwater flow caused the 1-13-77 Auto 98%
Hot 5 hrs.
RPS trip, high RC reactor coolant system pressure to increase, 15:54
..?**"
Shutdown pressure.
tripping the reactor on high pressure.
Ilot 100%
3-11-77 ihutdown 5 h rs.
. Turbine Trip.
TP 800-14 Manual Turbine Trip from 100%.
^"
22:05 Failure in the CRD system caused control rod
, 7-29-77 Ilot group 6 to dr,op into the core. This ruliid de-RPS 'I'dp
, in reactor power caused the RPS ::ystem 11:45 Auto 100%
Shutdown.13 hrs.
crease Variable pressure /
l t trip all four channels on variable pressural i
t empe rat ure,
temperature.
I
^"
I l-5-18 Full Ilot Auto Stop I.i p r actor trip from 100%
100%
power.
1' 00:43 Auto Shutdown 12 bra.
Oil Trip th> Peactor Trin l
Wind carried sheet metal debris from shack, l-14-78 Full 100%
liot 22 hru.
Turbine Trip grounded energized equipment and grounded 7:16 Auto Standby Generator Trip frame work causing 23A West Bus fault.
(s2bouer >
No Reactor Tr,ip.
i A light bulb was dropped into tle switch 3-20-78 Full Cold RPS Trip, high RC cavity sho'rting the -24V NN1"Y" B,us through hrs.
4:26 Auto Shut-pressure.
fuse 7-0-10., a 5 amp fuse leading to loss of l
down FW tripping the reactor from high pressure.
I Manually tripped Reactor because of increased 0%
llot Reactor power d'ue to drop in T ave. Initiated 7-22-78 Hanual Reactor Trip, 4
Manual 10,
Shutdown 44 hrs, by loss of boilers and CRD control power loss.
10 56 b T h.
amps Re-energized by itself.
4 RATED P0'JER 2T/2 IllTh C0f tERCI AL OPERATION 4-18-75 Pl. nit Ranciin seco PRIOR TO SCRAM ncAcron OUTAGE BREIF DESCRIPTION OF SCRAM SEQUENCE -
DATE status TIME TYPE OF SCRAM INCLUDE Tile ACTUAL INITIATOR OF.
MODE POWER AFTEn (llR)
THE SEQUENCE senAM During on-shift training, cov'er was being lifted S
dy Accidental manual move-off turbine trip 1. lock. Casket on cover came loose "E"
ment of auto stop trip-and. hung up and lifted auto stop tripping arm, 9-3-78 100%
7 tr.ipping main generator, main turbine & reactor.
,r 18:39 ping arm.
FV-33022 failed open and was then shut, causing Steady feed pumps to overspeed due tc suction pressure
~ ~
'"E" RPS Trip,liigh RC fluctuations.
8:05 Power 190%
llot 4 hrs.
pmssure.
Shutdown
}
Trip was caused by loss of vital power. Bus lA Steady due to a failure of inverter IA.
1-2-79 RPS Trip, high RC hate 20:28 100%
llot 10 hrs.
Power pressure.
td m Accidental trip of CRD 480V feeder breaker "B" I " " "
E"" " "
~~9 6%
S tdown 6 hrs.
RPS Trip, low RC. pres-Loss of power to the CRD system thus allowed the 1:22 8"#""
rods to drop.
Techn'ician inadvertently sh'orted an ICS power Steady supply ausir the trip. From reduction of F61 1-5-79 State 100%
S tdown 17 hrs.
RI'S Trip, high RC flow.
13:07 Power
~
Steady g -
A failure of the under voltage protection relay to the "A" inverter caused a loss of power to the lA
'"E" 100%
Shutdown 16 hrs.
RPS Trip, high RC vital Bus.
13:08 Powe r essue.
Reactor trip due to high pressure resulting from
- Nanual, 070 CoM
' 0"**
33g RPS Trip, high RC 7-1-79 running Shut-92 hrs.
13:45 down Turbine generator / reactor trip.' I.P turbine inter-Steady T/C tripped on auto stop ceptor valves went closed anJ started to cycle.
State 100%
llot which tripped reactor.
This causcJ ts.c T/C to sw'ng. T/C tripped on auto 7-12-79 7 gg, Power shutdown stop which in ture tripped the reactor.
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4 RATED POWER 2772 fMTh C0ft1ERCI AL OPERATION 4-1F-/S PLNIT uncno seco BREIF DESCRIPTION OF SCRAM SEQUElic'E -
PRIOR TO SCRAM ncAcTon OUTAGE DATE status TIME TYPE OF SCRAM INCLUDE THE ACTUAL. IHiTIATOR OF.
i MODE POWER AFTEn (HR)
THE SEQUEliCE i
SCRAM I
Reactor / Turbine / Gen. trip duc~to auto-stop trip, Hot Reactor / Turbine / Genera-no RPS channels tripped during'the transient.
9-12-79 100%
Shutdown 9 bra tor trip due to auto-Turb.ine E-H 0.P.C. caused severe transient on pgg Aut stop trip.
Tusb/Cen. Plant went to hot. shutdown following trip.
15:39 The positive imbalance limit was exceeded for 33%
Positive imbalance limit F.P. (4 pump flow) at +30% imbalance. This was Ht wis' exceeded for 33%
due to the fact that the top half of the core is 9-13-79 Shutdown 6 hrs.
F.P. tripping reactor, more " reactive" at the reduced coolant temp. and 1:54 Auto 30%
RPS Trip power dist ribution (at time of trip, T ave, for the top of the core was 14.3 *F below the temp.
at 100% F.P. and the bottom was actually 1.9'F abcse nominal
- T ave. )
While perf orming the exciter and gen,. startup tent m._._
FW demand procedure, AG4 the gen. tripped on over excitat-FW SU vlv
~
tion per Step 4.22. The base adjuster w.s used to-22K. Selecting" test]pn 10-13 79 byps viv.
Gemw WM set the voltage at sil%
llot 5 hrs.
trippin'g reactor, Step 4.24 caused a voltage jump (presummably) up
,18:14 Atm s dmp Auto all Si don to 23K which returned to just above 22K. The other operator then pressed the regulator voltage ad-stations juster pushbutton momentarily. At that instant.
in manual
-the generatur t ripped, f
Feed pump "A" discharge header pressure dropped
,Han. with below the trip setpoint. FW level was being con-exceptns.
Y 1-5-80 of both Hot Reactor trip on Reac' tor /
lower than normal before the " low" level went 2:40 TBV & Adv 100%
Shutdown 15 hrs.
C-P t./ Fed.
limit signaled the startup valves to operate. As both strt a result, the valves opened more than necessary j
up & main causing a header, pressure decrease below the FW viv &
trip point.
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4 RATED POWER 277.^ INTh C0lfERCI AL OPERATION 4 l'; M PLANT R^neno sgco BREIF DESCRIPTI0il 0F SCRAM SEQUENC'E PRIOR TO SCRAM ncncToR OUTAGE INCLUDE Tile ACTUAL INITIATOR OF.
s nTus TIME TYPE OF SCRAM MODE POWER AFTER (HR)
THE SEQUENCE DATE SCRAM Inadve rtent automatic rod withdrawl due to power Instrumentation meccaling.
5-11-80 RPS Trip, high pressure 15:24 11%
ilo t 9 hrs.
Shutdown Ground on 3E10 t ripped 2E2 causipg "A" f. "B" main cire pump discharge valves to close. condenser *la' RPS Trip, high RC uum dec reased.*
State flot ggg pressure.
5-30-80 Power Shutilown 3 hrs.
14:14 a
Dia Han D inverter tripped causing NNI's to transfer and l
D RPS I hrs.
RPS Trip, higli RC caused feedwater to cut back increasing RCS pres-8-12-80 channel 1 i
96%
llot P 888" sure tripping reactor..
7:48 Byps-all Shutdown other ICS Sta. Auto Loss of service & instrument air pressure due to
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instrument air pressure decreace below Feedwater Steady g
State llot 8 hrs.
RPS Trip, high RC valve " lock-up" pressure.
Q 10-28-80 P wer shutdown pressure.
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- Additional :aintenance resulted in a 22 day outar,e.
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