ML19210D645

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Forwards Info Re Power Operated Relief Valve & Safety Valve Lift Frequency & Mechanical Reliability,In Response to NRC
ML19210D645
Person / Time
Site: Rancho Seco
Issue date: 11/16/1979
From: Mattimoe J
SACRAMENTO MUNICIPAL UTILITY DISTRICT
To: Reid R
Office of Nuclear Reactor Regulation
References
NUDOCS 7911270423
Download: ML19210D645 (23)
v • d • e


Text

Y' OSMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 S Street, Box 15830, Sacramento, California 95813; (916) 452-3211 November 16, 1979 Mr. Robert W. Reid, Chief Onerating Reactors Branch #4 Division of Operating Reactors U.S. Nuclear Regulatory Commission Washington, D. C.

20555 Docket No. 50-312 Rancho Seco Nuclear Generating Station Unit No. 1

Dear Mr. Reid:

Your letter of September 28, 1979, requested information con-cerning PORV and safety valve lift frequency and mechanical reliability.

This letter forwards the requested information.

Sincerely, John Mattimoe Assistant General Manager and Chief Engineer e

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. fI I-l ATTACHMENT I (12 PAGES)

Request i According to statements made by B&W, there are approximately 146 documented occasions where PORV actuation

  • occurred at B&W facilities prior to the accident at Three Mile Island, Unit 2 (TMI-2).

For each of these events which have occurred at your facility (ies), provide the following information:

a.

The cause of the event; b.

the initial power level prior to the transient; c.

Indicate which of these transients caused the reactor to trip on hiah ROS pressure and/or caused the safety valves to lift; and, d.

If you assume that the present setpoints for high RCS pressere trip and PORV actuation were in effect at the time of each of these transients, estimate whether either of the followino would have taken place:

(1)

PORV actuation, and (2) liftina of the safety valves.

(For this item assume no credit for the anticipatory control-grade reactor trip on loss of feedwater or turbine trip.)

Response

The requested information has been compiled in the followina plant specific tables (Reactor trips with a PORV actuation).

In addition, there have been seven (7) instances when the PORV stuck open - three (3) when the plant was at power and four (4) when~it was not producing power.

a.

At power:

(1)

Oconee-3, June 13, 1975 (Feedwater oscillations while shutting down)

(2)

Davis-Besse 1, Sept. 24, 1977 (Loss of Feedwater)

(3)

TMI-2, March 28, 1979 (Loss of Feedwater) jl90

I-2 ATTACHl1EllT I (Cont'd) b.

flot producina power:

(1)

Oconee-2, August 15, 1973 (Pre-op Testing)

(2)

Oco.iee-2, flovember 6, 1973 (RCS Heatup)

(3)

Davis-Besse 1, October 13, 1977 (Hot Standby)

(4)

TMI-2, March 29, 1978 (Zero Power Physics Testing) 1398 255 e

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PFICTOR TR11'S WITIL A POTIV ACTt'ATION IT PPrSENT SFTPOINTS

pgp, "AO I

O INITI AT.

SAFETT TRANS!ENT TRIP POWER VALVES PCRV Lir? SAFETY DATE CLASSITICATION SIGNAL CAL;SR Cr TRANSIENT LEVrL L!rTED7 ACTUATION?

VALVES?

5-5-73 Loss of reedwater Manual Operations Error Tripped 18 No No No MFW Pump 5-16-73 Loss of reedwater Hi RCP operator rrror 15 No No No 5-23-73 Loss of reedwater Hi RCP Operator and/or Procedure 25 No No No Error 5-26-73 Loss of reedwater Hi RCP Operator and/or Procedure 35 No No No Error 5-27-73 Loss of reedwater Hi RCP Began as CRDM rault 40 No No No 5-28-73 Loss of reedwater Hi RCP Atterpt to Transfer from 40 No No No B to A FWP

$~30-73 Loss of reedwater Hi RCP Cleaning Hotwell Pump 40 No No No S trainer 6-9-73 Loss of reedwater Hi RCP Switching Powdem Units 40 No No No 6-13-73 Turbine Trip Manual CRDM rault rollowing 52 No No No Turbine Trip Test and ICS Runback Signal 6-14-73 Loss of reedwater Hi RCP Maintenance Work on Hotweil 40 No No No

(?)

S trainer 21-73 Loss of reedwater RCP/

Tripped Hotwell Pump

\\9 No No No Temp Initiated rWP Trip Ratio

.............................. P rior to Co mme rc ia l ope ra t ion - - - - - - - - - - - - - - - - - - -

7-15-73 Loss of reedwater Hi RCP raulty Speed controller on 75 No No No a Main rW Pump 8-11-73 Turbine Trip Loss Pwr Inadvertent Closure of 85 No No No to Pumps Turbine Intercept Valves Ind.

9-16-73 Turbine Trip Hi Temp Manually Initiated Turbine 40 No No No Pressure Trip Decreased Closing Ratio Setpoint of Bypass Valves 10-12-73 Turbine Trip Hi RCP Main Steam Evpass Valves 20 No No No did not open: Operator put rods in manual 10-26-73 Turbine Trip Hi ECP Loss of Condensor vacuum 75 No No No 12-11-73 Turbine Trip KL RCP SpurLous MWe Signal 90 No No No Detseted by EHC System lead to Turbine Trip 8-23-74 Load Rejection El RCP Unit Loss of Electrical 95 No No No Load 7:ceptance Test 3-12-75 Loss of reedwater Hi RCP Shorted Transistor in 25 No No No ATc Controller 4 22-75 Turbine Trip Hi RCP Loss of EHC Control Power 100 No No No 4-23-75 Loss of reedwater Hi RCP Rapid reedwater Oscillations 46 No No No 6-8-75 Turbine Trip Ni RCP Low EHC Hydraulic Pressure 100 No No No T.T 6-9-75 Loss of reedwater Hi RCP rw riew Oscillation 30 No No No 8-2-75 Instrument railure Hi RCP railure of Temperature 75 No No No Switch on Stator Coolant System 8-8-75 Turbine Trip Flux /

Positive voltaae Spike in 92 No No No riow Turbine Sreed Error Circuit 1-22-76 Turb,no Trip Hi RCP Loss of Excitation on 100 No No.

No Generator 5-31-76 Loss of reedwater Hi RCP rwP Turbine fH Speed s15 No No No Mmmentartly Decrcised when Switching from A4xiliary to ma,n Steam 1T98 256

14 pnyv tetr3 Tie-a t -. w a r-1 e r ve D RfAC~oR TRIPS WITl! A Pol;V ACTUATIM IF PPT.9FNT SFTPOINTS P2R INITIAL FAFhiY

"^

TRAN9 f rNT TRIP POWER VA!.VER POPV LIFT S AFETY CATE CLASSIFICAT!DN SICt!AL CAUGE nF TRANSITNT LEVEL LITTED7 ACTUATIC%7 VALVES 7 6-27=76 Instrument railure HL RCP Shert in Signal Arp for 100 No No No RPS Flow Indications Secondary Flow Runback 7-7-76 Hi RCP Personnel Error 99 No No No 7-14-76 Loss of reedwater and Power Hi PCP ICS Hand Power Circuit 100 No No No Supply railure Breaker Tripped when Circuit was overloaded with Calibration Equipment 8-14-76 Rod Drop Hi RCP Heat and Moisture Affected 6)

No No No Electrical Components in CRD System Cabinets 4-3-77 Instrument Failure Hi RCP Failure of ICS Component s15 No No No 4-24-77 Turbine Trip Hi RCP Nisaligned Linkage Caused 68 No No No High MoiJture Separator Reheater Drain Tank Level 5-24-77 Turbine Trip Hi RCP Loss of Condenser Vacuum 70 No No No 6-6-77 Turbine Trip Hi RCP Personnel Error 99 No No No 10-18-77 Loss of reedwater Hi RCP Standby condensate Pumps 15 No No No Off 12-30-77 Loss of reedwater Hi RCP Personnel Error - Inadver-100 No No No tent Closure of MFW Block valve 4-1-78 Turbine Trip

h. RCP High Level in Motsture 95 No No No separator Tank Caused by Failure of MSDT Dump valve and MsDT Level Control valve 8-2-78 Turbine Trip and Power Hi RCP EHC-DC Power Lost 100 No No No Supply Ts11ure 12-25-78 Power Supply railure Mi RCP Blown ruses Led to LorW 10 No No No 3-23-79 Instrument railure Mi ACP Startup FW Summer Modula 100 No No No railed e

1398 257 e

9

1-5 pnpv tc-tmm netwr-2 re w 11 REACTOR TRIr* WITH A PnPV ACTUA7.ON IP *RT9FNT $ETPOINTS PIR INITIAL SAFh!Y HAD 8 FEN USED TRANSIFNT TRIP POWER VALVTS PORV LIFT SAFETY DATE CLASSIFICATION SICNAL CAUSE OF TRANSIENT LEVEL LIFTED 7 ACTUATION 7 VALVES 7 12-2-73 Loss of Feedwater HL RCP Leak in 1* Line Around 15 No No No One FWP.

Ope ratnr Manipulation of FW SU valves Led to LOFW 12-3-73 Loss of reedwater Ni RCP Control Rod droups 9

No No No 6 and 7 Lost Proper overlap 12-12-73 Loss of Feedwater Hi RCP Too Larce a Pressure Less 30 No No No in Powdex Units. Conden-sate Booster Pumps tripped 1-4-74 Turbine Trip Hi RCP Erroneous Activation of 75 No No No Breaker Failure Relay System 5-30-74 Manual Rx Trip Manual Operator Mistakenly Injected 75 No No No HP1 Water into RC System 6-13-74 Turbine Trip Hi ACP Turbine Intercept valves

?

No No No closed Due to Faulty Pot

- - = = = = = - = = - - - - - - - - - - - - - - - - - - - - - - Prior to Commercial Operation - - - - - - - - - - - - - - - - -

9-17-74 Turbine Trip Hi RCP TT Curing Testing of Thrust 100 No No No Bearing Wear Detector 9-23-74 Power Supply Failure and HL RCP ICS Power Lost During 95 No No No Loss of Feedwater Switching of reeds to Inverter. Main reed Pumps Tripped 3-27-75 Load Rejectic Hi RCP Loss of Electrical Load 100 No No No Test During Startup 3-27-75 Instrument Failure Manual Loss of Condensor vacuum 15 No No No Led to FWP Trip 4-1-75 Turbine Trip Hi iTP Manual Trip as Part of 100 No No No Turbine / Reactor Trip Test 8-5-75 Loss of reedwater Hi RCP Blown Casket on Emergency 62 No No No Governor Lockout Valve in Hydraulic Control System 8-23-75 Loss of Feedwater Manual Malfunction nf Condensor 14 No No No Vacuum Switches Tripped FWPs.

Reactor Manually Tripped 9 19-75 Loss of Feedwater Manual FWP TrLp on Low Vacuum.

10 No No No Manual Reactor Trip 7-12-76 Turbine Trip Hi RCP FW Oscillation ocurred 23 No No No While Taking Main Turbine Off LLne 7-27-76 Loss of reedwaten Mi RCP Steam Leak on Main Turbine 20 No No No Caused Load to Hold at 204.

ICS Caused FW Oscillations 9-7-76 Turbine Trip Hi RCP Back-Up Speed Control System 100 No No No railed and Intercept valves Closed During TT Test 5-4-78 Turbine Trip Hi RCP Moisture separator Level 100 No No No Controls railed to Function 10-17-78 Loss of Feedwater Hi RCP Air Line Blew Of f Startup 100 No No No FW Valve 10-30-78 Loss of Feedwater Hi RCP Welding Crew Ignited 011

$5 No No No Around FW Pump with Sparks, Causing FWP to Trip 10-30-78 Loss of Feedwater Hi RCP FW Pump Leak. [ witching of 12 No

. No No Pumps not Accomplished 9

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RFACTOR TRIPS WITH A PORV ACTL% TION IF PPESENT METPOINTS pg,hTY D BEEN USED INITIAL SAF TRANStENT TRIP PnwrR VALvfS poRy L!rT SAFET DATE CLASStr! CATION SICNAL CAUSE OF TRANSTENT LEVEL LITTE07 ACTUATION 7 VALVES 7 10-13-74 Loss of reedwater Power to Debris obstructed Hotwell 15 No No No Pumps Pump Strainer 10-17-74 Loss of reedwater Hi RCP Debris obstructed Hotwell 16 No No No Pump Strainer

- - - - = = - - - - - - = = = = = = = = = = - - - = = = = = - - P r io r to Comme rc ia l Ope r a tion - - - - = = = - - = = = *-- - = = -

4 7-75 Loss of reedwater Hi RCP Servicing Powdex Tripped 75 No No No Condensate Booster Pump 4-30-75 Load Rejection Hi RCP Loss of Electrical Load 100 Yes No' No Test Low RCP While Shutting Down, Turbine 19 No No No 6-13-75 Switched to Manual at 194, Sypass Valves Opened, ULD Increased FW Demand --6 FWP and DTSG Level oscillations 7-1-76 Turbine Trip Po'ver to TT or Low Turbine Shaf t Oil 98 No No No Pumps Pressure 4-6-77 Turbine Trip Power to TT on Momentary Loss of 100 No No No Pumps DC Power to EHC 8-21-77 Loss of reedwater Hi RCP Manual Adjustments to rw 15 No No No by Operators 11-3-78 Loss of reedwater Hi RCP TT Sue to Low FWP Discharge 44 No No No Pressure 2 21-79 Instrument railure Hi RCP Noise Spike on ICS Cable 99 No No No After CRDM Testing

.)

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'SETPOINT woULD KAVE BEEN REACHED, Rttr BLOCK VALVE WAS CLOSED.

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!.7 PORV ACTPATfrM9 - DAVT"-BF9MP-1 PIACTOR TRIPS WIT 11 A PORV ACTf'ATION IF PRFSrNT SFTPOINTS pg,hTY HAD BEEN USFD INITIAL SAF TRANS!ENT TPIP POWFR VALVF.S DORV LIFT RAFETy DATE CLASSIFICATION SIGNAL CAUSE OF TRANSIENT LCVFL LIFTED 7 ACTUATION 7 VALVES?

9-2-77 Turbine Trip Lo RCP OTSG Overfed by Operator

% %5 No No No 9-24-77 Loss of Feedwater Manual

" Half-Trip" of SFRCS 9

No No No Isolated OTSCs 10-23-77 Loss of Feedwater Lo PCP SFPCS Caused Isolation of 16 No No No 1 OTSG, Later Both

.............................. -.... Prior to Commercial Operation - - - - - - = = = = = = - -

12-16-77 ICS in Manual Lo RCP Overfed "B' OTSG. Operator 11 No No No had p*FW Pump in Hand 12-30-77 Loss of Feedwater Lo RCP TWP Tripped on High Exhaust 72 No No No Casing water Level 1-31-78 Loss of Feedwater Hi RCP Spurious SFPCS Trio After 67 No No No Performing SFRCS Monthly Test 3-1-78 Loss of Feedwater Hi RCP SFRCS Actuated on FW/STM 49 No No No Pressure aF Demerator Level Cont. valve Failed shut 4-2-78 Turbine Trip Lo RCP TT Test - During Runback, 75 No No No Rx Tripped, Overfed OTSG's 9-10-78 Turbine Trip Lo RCP Tripped Turbine for Test s75 No No No TP-400-14 9-28-78 Instrument Failure Lo RCP Loop 2 RCS Flow KMTR Failed 90 No No No Low, Runback 9 204/ Min Initiated. Operator Lost Control 10-3-78 Turbine Trip Lo RCP TT Caused by Starting 2nd 68 No No No ElfC Pump.

ICS oversupplied Fw

.10-29-78 Loss of Feedwater Lo RCP EM Relief Cycled and Stuck 4

No No No open Too Long 11-13-78 Power Supply Failure Power to Fuse for RC Pump control 99 No No No Pumps Circuitry Blew 1-12-79 Loss of Feedwater Hi RCP Technician Shorted Inverter 100 No No No causing Loss of vital Bus Y2; STRCS Trip 2-22-79 Lose of Feedwater Nf RCP Palfunetfon fn' Turbine Speed 87 No No No Control System Led to SFRCS Actuation a

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1-8 POPV ACTt3Trew:. n menn ~cn REACTOR TRIPS NITtI A PCRY ACyt:ATION Ir PPISENT SETPOINT PIR INITIAL SArhTV HAD RFEN USED TRANSICNT TRIP POWrR VALVES PORV L!rT SAFETY DATE CLASSITICATION SIONAL CAUSE Or TRANStril?

LEVEL L!rTED7 ACTUATION 7 VALVES 7 11-19-74 Loss of reedwater Manual rDW oest11ations During 25 No No No ICM Tuning 11-22-74 Loss of reedwater and Hi RCP Technician Misoperation.

32 No No No Power Supoly railure Power Lost to "Y" and "Z"

NNI Busses 12-4-74 Loss of Teodwater Hi RCP Inadvertent Actuation of 40 No No No Reheater Intercept Valve 12-15-74 Rod Drop (CRP. 6 & 7)

La RCP CRDN Kotor raults Programmer 39.5 No No No As sembly 12-17-74 Rod Drop (CRP. 7)

Lo CRP Same as Preceding Transient 41.3 No No No 12-26-74 Loss of reedwater and Hi RCP railure of 2 SCR's in "C" 39.5 No No No Power Supply railure Inverter 12-31-74 Power Supply railure Presourc/ Operator Error in Paral-40 No No No Temp.

leling Inverters 2-12-75 Turbine Trip Hi RCP Spurious overspeed Trip 92 No No No signal 2-10-75 Manual Load Rejection Lo RCP Poor ICS Tuning 75 No No No for Trip 4-14-75 Loss of reedwater Hi RCP Startup Valve in Auto 15 No No No (Closed), but "A* OTSG Blew Doun

................................... P rio r to Comme rc ial Ope r a tion - - - - - - - - - - - -

6-15-75 Loss of reedwater Hi RCP Transferring Stern Supply 13 No No No for rWP from AUX. to Main Steam 10-10-76 Loss of reedwater Hi RCP FWP Speed Control Lost.

13.6 No No No FWP Governor was Dirty 10-10-76 Loss of reedwater Hi RCP Same as Preceding Transient

?

No No No 1-13-77 Loss of reedwater Hi RCP Technician Shorted out FWP 98 No No No Thrust Bearing Indicator 1-5-78 Unknown Hi RCP Unknown 100 No No No (7) 3-20-70 Loss of reedwater Hi RCP Dropped Light Bulb Shorted 72 Yes No No NNI Cabinet 12-31-78 Loss of reedwater Hi RCP Cordensate valve rallure 100 No No No 1-2-79 Loss of reedwater Hi RCP Loss of Vital Bus LA 100 No No No 1-5-79 Loss of reedwater El RCP Technician Shorted Nires 100 No No No Ln ICS Cabinets e

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!.9 PPPV ACTt'ATir*19 - 410-1 REACTOR TRIts MITil A PCRV ACTUATION IF PPESENT SETPOINTS PIR HAD RFrN UST.D INITIAL SArkTY TRANSIENT TRIP POWrP VALVFS PORV LIFT SAFETY DATE CLASSIFICAT10N SIGNAL CAUSE OF TRANSIFNT Lgt'EL LIFTFD7 ACTUATION 7 VALVE 97 10-15-74 Loss of Feedwater Hi RCP

  • A" FWP Tripoed on High No No No Vibration 12-6-74 Loss of Feedwaser Pressure / Loss of Vacuum Due to "B*

80 No No No Tamp Main Chiller Getting Wet and Shorting

- - - - - - - - - - - - - - = = = = = = - - * - = = - - - - - - - P r io r to Comre rcia l Ope r a tion - - - - = = - - - - - - -

1-6-75 Load Rejection Hi RCP Generator Tripped on 98.5 No No No Differential Current Due to Loss of Buss Cooling 5-15-75 7

Pwr/

Flow Csci11ations occurred 100 No No No Imbalance During Maneuvering Flow 6-6-75 Instrument Failure Pwr/

Loose Connection on Loop 99 No No No Imbalance "B" Tc Signal Flow 7-3-75 Instrument Failure

'wr/

Technician Grounded TH 95 No No No Imbalance Signal to ICS Flow Pressure / Operator Lost Htr. Drain 50 No No No 7-23-75 Lees of Feedvarer Temp Pump Which Tripped FWP 7-8-76 Loss of Feedwater/ Power Hi RCP Inst. Techs Shorted NNI 94 No No No Supply Failure Power Supply 9-23-76 Turbine Trip Hi RCP Turbine Tripped Whan Vibra-99 No No No tion Trip Module was Reinserted by Technician 12-20-76 Rod Drop / Power Supply Hi RCP Rod 8 in Group 4 Dropped.

64 No No No Failure Coupled with Loss of Y-11 Inverter 6-19-78 Turbine Trip Hi RCP Technician or Operator

?

No No No Error in opening wrong Feeder Breaker 9-16-78 Hi Flux Burned out Control Air

?

No No No Solenoid on MSIV 10-13-78 Instrument Failure Pressure / RPS Channel *B*

PC 7

No No No Temp Flow Signal Failed 12-20-78 Instrument Failure Pressure / Low Stean Pressure 99 No No No Caused by LVDT f.inkage Tamp Breating t

_ ~._

f=lJ rnny AcTt?T'rNC

'"'-1 REACTOR TRtFS WITH A PORY ACTUATION 1F PRE 5EMT SETPOIMTs PER MAD BEFN USED INITIAL

$AFETY POWFR VALVES FORV LIFT SAFE 1 TRANstENT TRIP DATE CLA55tFICAT10N SIGNAL CAUSE OF TRANSEENT LEVEL LIFTED 7 ACTUATION 7 VALVES!

6-18-74 Loss of Feedvater Et RCP "A" !astrument NIR 7

No No No Compressor Trtpped on Thermal Overload u-Pressure / LOFW Noticed Prior to 15 No No 7-13-74 Loss of Feedvater Temp 3-Sec. Rod Withdrawal Pressure / Techattian Crounded 76 No No No 7-14-74 Less of Feedwater Temp Tgyg $1gnal 8-13-74 Lead Rejectica (Test)

Mi RCP Cenerator Trip Test 98 No No No 8-30 74 Turbine Trip N1 RCF Turbine Bearing Failure 75 No No No

... - - -............. - - -.. -......... P r i o r t o C o mm e r c i a l O p e r a t i o n - -... -.. - - - - - - -

3-30-75 Tuttiae Trip Mi RCF Erroneous $1gaal from 100 No No No Faulty 701 Relay Indicated Loes of 125-V supply to Turbine ERC Systeme 5-9-75 Turbine Trip NL RCP "3" Moteture separator 100 No No No Drata Tank K1gh Level Trip Device Shorted 6-18-75 Turbine Trip 51 RCF Voltage spikes Transmitted 100 No No No Isto Tarbine EHC System 11-14-77 1CS Ceaponent Failure Flus / Flow ICS Signal-Converter "L"

100 No No No Imbalance Module Failed to Midrange S

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[*ll FORY ACTUAffoMS - T"f-!

REACTOR TRIPS WITH A FORY ACTUAT10N IF PRESENT SETFO!NTS pgg INITIAL SA'hTY NAD SEEN USED TRAMS!ENT TR!F F0WFR VALVES FORV LIFT SAFETY DATE CLAS$tFICATION

$1CMAL CAUSE OF TRANS!*NT LEVEL LIFTED 7 ACTUATION!

VALVES?

No Funge la Loop "A"

51 anal. Fuse 11em to 2-tv.

RCP-2A Already Out 4-19-78 Lees of Feedwater 51 RCP Operator Elev Down 15 No No No Condensate Strataars 9-20-78 Less of Feedwater 51 RCP Valving Error Tripped Ceedensate Rooster Pump 24 No No No 9-21 78 Low Feedwater 51 RCP Feed Fuay and Feed Reg.

19 No No No Valve Probleme 9-25-78 Lead Rejection Normal Mi RCP Migh Pressure Due to 17 No No No Beducing Lead on Turbine.

Incorrect Suetion Pressure Switch or Logic Error on C.E.

Fumps caused FWF Trip 10-14-78 Lose of Feedwater La RCF FVF-1A Lost 26 No No No 11-7-78 Loss of Feedwater Pressure / TP-800-05 (peactivity 92 No No No Tamp Coefftetents; was betat performed at TAvg = $88F.

Wester Drain Tank Law Level Alara Tripped FWF-13.

--= = = = = = - - - = = = = = = - - - - - = = - - - - = = = = - - Frior to Commercial Operation - - - - - - - - - - - - - -

1-15-79

!astrument Failure La RCP Atmospheric Relief Bellows 5

No No No Failed

)v)8 264

!=l2 PHpV 7 rt ATTPJts - CPV9TA L P tVER-1 REACTOR TRIPS WITil A PORY ACTT'ATION Ir PRISrNT SETPOINTS PIR HAD BFIN USED INITIAL SAFETY TRANSIENT TRIP PnifER VALVTS PORV L!rT $AFETY DATE CLASSIr! CATION SIGNAL CAUSC OF TPANSIENT LEVC LITTED7 ACTUATION 7 VALVES?

1 30 77 Instrument railure/ Turbine Lo RCP Manual TT Due to Low 15 No No No Trip Turbine Header Pressurn Coupled with Incperable MW Meter 3-2-77 Power Supply railure.

Loss of 120 VAC-D Vital Bus was 40 No Ao No CRD Pwr Lost Due to railure of Diode in "B" Inverter Manual Reactor - Turbire Trin 40 No No No 3-9-77 Test TP-800-14

Prior to comme re tal Operation - - - - - - - - - - - - - - - -

4-21-77 Power Supply railure Power /

  • X* Power supply to ICS 46 tio No No e pumps Lost Due to Blown rune Martal Part of Test (Outside 20 No No No 4-23-77 Control Room) 10-26-77 Power Supply railure/

Hi RCP Inverter *A* Tripped 100 No No No turbine Trip / Loss of Causing a Loss of Powet reedwater to vital Bus A*

1-6-79 Turbine Trip Manual TT rollowed by FW Elock 71 No No No Valve rWV-30 Sticking Open or Partially Open 1-17-79 Loss of readwater Manual Solenoid railure on Inlet 100 No No No Seawater Block Valve to Secondary Services Heat Exchanger "A*.

1-30-79 Loss of reedwater Lo RCP Reason for Decrease in 100 No No No FW Not Stated 7-17-77 Rod Drop Manual Crp. 1 Dropped During 90 No No No Surveillance Test 11-13 77 Loss of reedwater Pressure / rW Upset While Passing 57 No No No Temp Block valve.roint.

Cause is Operator Control and Poor Control System Operation / Performance I

1798 263 9

e

II-l ATTACHt1ENT II (7 PAGES)

Request 2 Provide a complete listing of reactor trips for your facility (ies) which have occurred subsequent to the revised setpoints for PORV actuation and high RCS pressure trip.

This listing should include the followino items:

a.

The cause of each event; b.

The initial power level prior to the transient ;

Indicate which of these transients caused the PORV and 'or c.

safety valves to open; and, d.

If the old (pre-TMI-2) setpoirts for high RCS pressure and PORV actuation were in effect at the time of these transients, estimate whether any or all of the following.would have taken place:

(1)

PORV actuation; (2)

Reactor trip on high RCS pressure, and (3)

Lifting of the safety valves.

Response

This information has been compiled and is presented in the attached tables.

.e hypothetical actuation of the PORV and/or safety valves and high pressure trip assuming the old setpoints had been in effect is not based on any analytical technique.

Rather,'Enaineerina judgement, coupled with past operating history led to these results.

3z93 266 O

i

II-2 REACTCR TRIPS S!!;CE TMI- - OCONEE 1 If Old Setpsints lied Er.cn U<ed Initial PORY PZR FORV Trip on liigh Lift Safety Date Trar.sient Classification Cause of Transient Pov.er Lifted?

Safety Actuction?

Pressure?

Valves?

I Level Valves Lifted t

f.

6-11-79 Loss of feedwater Elic Card Failure 99 No No No No No 6-11-79 nunual Reactor Trip Low OTSC Level I

No No No No No 6-17-79 Two RC Pumps Tripped 97 No No No No No l

l 8-6-79 Turbino Trip Valving-out of 40 No No No No No i

Pressure Switch l

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s-~~s4 II-3 REALTOR TRIPS SINCE 1NI-2-0CONEE-2 If Old Setpoir.ts liad Been Use;d Initial PORY PZR PCRV Trip on liigh Lift Safety Date Transient Classificaticn Cause of Transier.t Pob:cr Lifted?

Safety Actuation?

Pressure?

Y11ves?

Level Valves lifted 5-7-79 Loss of Feedwater Underfed OTSG 2A 15 No No Yes Yes No 6-4-79 Loss of FecJwater Halfunction of Main 30 No No Yes Yes No FDW Block Valve 7-18-79 Turbine Trip?

Lightning struck No No No No No Substation Breaker

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CJC) c s-)

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Safety Actuation?

Pressure?

Valves?

Level Valves

, Lifted 9-18-79 Turbine Trip Perturbation in 99.8 No ha Yes No No EllC Fluid Pressure 9-26-79 Turbine Trip Failure Of Power 100 No No Yes No No Supply For Turbine Throttle Pressure Limiter XHTR 9

8 sek C)

CO r0 C:r' W

f Y

0

?

am.ma 11-5 REACTOR TRIPS SINCE TMI-2-CRYSTAL RIVER-3

!f Old Setpoir.ts Hcd Decn used Initial PORV PZR PCRy Trip on High Lift Safety Date Transient Classification Cause of Transient Power Lifted?

Safety Actuation?

Pressure?

Valves?

Level Yah es Lifted 8-16-79 Loss of Feedwater FW Upset After RCP Trip 73 No No Yes No No 8-17-79 Loss Of Fee' water FW valve Actuator 47 No No Yes No No Failure 8-17-79 Loss Of Feedwater FW Going From one To 48 No No Yes No No Two-Pump Operations; "A" Pump Speed lower And "B" liigher Than Required 8-17-79 Loss Of Feedwater Operator went From 24 No No Yes No No blanual To Auto With ICS With Off Normal Plant Conditions 9-18-79 Loss Of Feedwater FWP Regulator Failed 72 No No Yes No No n

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m 11-6 REACTOR TRIPS SINCE Dti-2-RANCIO SECO If Old Setpoints !!ad teen Used Initial PORV PZR PORV Trip on itigh Lift Safety Date Transient Classificaticn Cause of Transient Porter Lifted?

Safety Actuation?

Pressure?

Valves?

Level Valves lifted 4-22-79 Loss of Feedw;ter Loss of"A" inverter 100 No No Yes Yes No 7-1-79 Loss of Feedwater Test of STP-070 13 No No Yes No No 8-12-79 Turbine Trip Spurious Activity 100 No No No No No In Overspeed Protection C'rcuit 9-12I79 Turbine Trip Spurious Activity 100 No No No No No In Overspeed

-Protection Circuit 9-13-79 Unspecified Imbalance on Restart 30 No No No No No h

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REACTOR TRIPS SINCE ntI-2. ARKANSAS gg gg Initial Por,V PZR P0fiV Trip on High Lift Safety Date Transient Classificaticn Cause of Iransient Powcr Lifted?

Safety Actuation?

Pressure?

Vahes?

Level Valves lifted i

I 8-13-79 Turbine Trip Switchyard Relay Failure 75 No No Yes No?

No Turbine Trip Cpvernor Valve 75 No No Yes No?

No Control Failure

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III-l ATTACHMENT III (3 PAGES)

Request 3':

Provide an estimate of the increase in reactor tr.ip frequency since lowering the high pressure trip setpoint and adding the anticipatory reactor trip.

Include a review of the design criteria for the number of reactor trips over the plant life and evaluate the effect of the increase in trip frequency on these criteria.

Also provide the basis for the acceptable number of reactor trips in terms of the limiting component (s).

Response

A.

An increase in reactor trip frequency will result from a lowering of the high pressure trip setpoint and the addition of the anticipatory reactor trip.

To estimate the effect of these changes, total reactor trips were divided into two (2) categories:

1.

Category 1 - Trips that should not be affected by the above changes (e.g., total loss of.feedwater, since this led almost invariably to a reactor trip with the old setpoints; power to flow trips; test trips; etc.)

2.

Category 2 - Trips that are affected by the above changes (e.g., high pressure trips, feedwater upsets, and turbine trips).

Category 2 trips are listed in the following table (Table 1) in the "A" columns while total trips (Category 1 plus Category 2) are listed in the "B" columns.

The number of trips and frequencies in Table 1 are based on commercial calendar time. The post-TMI-2 frequencies should be viewed with caution as they are based on only a short operating history following the setpoint changes.

Ideally (i.e..

with a large enough data base), the Category 1 trip frequency ("B" column minus the "A" column) should be similar for the pre-and post-TMI-2 periods.

The fact that this js not the case can be attributed to the difference in calendar time and also statistical variations of the pre-and post-TMI-2 samples.

However, on the average, it can be observed that the trip frequency in Category 2 (i.e.,

"A" column) has increased by approximately a factor of 3 (0.23 to 0.71); which would almost double the total trip frequency.

Thus, although the data indicate approximately a doubling of the average trip frequency, the following must be considered:

1.

There has been a relatively short period of operation since the changes.

2.

There have been many startups and shutdowns during the post-TMI-2 period.

~

)198 273

III-2 ATTACHMENT III (Cont'd) 3.

As operators, become f amiliar with the revised setpoints and operating conditions, it is reasonable to assume the trip frequenci(s maydecrease.

B.

The structural design criterion for the number of reactor trips over the life of the plant is to keep the fatigue usage f actors of all RCS components below 1.0 as supported by the component stress analysis.

In general, this usage factor is made up of contributions due to all specified transients.

Since the largest contribution to the fatigue usage factor is attributable to heatup and cooldown transients, with reactor trips producing only a small effect, the increase in trip frequency-(indicated by the average data to date) should only have a small effect relat'ive to plant life.

As a part of the total allowable transient picture, 400 reactor trips are specified.

Assuming a 40-year life, this translates into 10 trips per year or.83 per month.

With the pre-TMI-2 setpoints, only the most recent plants to come on line (Davis Besse-1, Crystal River-3, and TMI-2) exceed this figure.

As these plants accumulate operating experience, their trip frequencies would be expected to decline under the pre-TMI-2 setpoints.

With the new setpoints, three plants exceed 0.83; however, for the reasons discussed in A above, it is premature to draw any conclusions over the life of the plant based on the little data available with these setpoints.

C.

To determiia the acceptable number of reactor trips in terms of the limiting component (s), it is necessary to review the stress report for each component and plant and evaluate the fatigue usage factor.

If the number of trips were to exceed 400 on any plant, that plant would have to be reanalyzed based on actual transients and the limiting component would be a function of these actual transients plus those that would be expected throughout the remainder of the plant's life.

It is important to recognize that usage factors below 1.0 represent design margin in the plant design.

Any change that increases the frequency of transients causes a decrease in this margin whether the actual limit is reached or not.

Therefore, steps (such as raising the high pressure trip setpoint, etc.) should be considered to reduct the trip frequency thereby improving desian and safety margins.

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