ML091120075
| ML091120075 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 03/31/2009 |
| From: | Dominion Nuclear Connecticut |
| To: | Caruso J G Operations Branch I |
| Hansell S | |
| Shared Package | |
| ML082600232 | List: |
| References | |
| 50-336/09-301, TAC U01634, FOIA/PA-2011-0115 50-336/09-301 | |
| Download: ML091120075 (185) | |
Text
MILLSTONE POWER STATIONABNORMAL OPERATING PROCEDURE Level of Use C ontinuous Loss of Shutdown CoolingAOP 2572Rev. 009-03Approval Date:_________03/27/08
____________________Effective Date:_________06/18/08
____________________
AOP 2572Revision 009-03Page 2 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW1TABLE OF CONTENTS1.0PURPOSE3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0ENTRY CONDITIONS4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0INITIAL ACTIONS FOR LOSS OF SDC5. . . . . . . . . . . . . . . . . . . . . . . . . . . 4.0SDC LOST DUE TO LOSS OF SUCTION PRESSURE OR RCS INVENTORY8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0SDC LOST DUE TO TRIPPING OF RUNNING LPSIPUMP21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.0SDC LOST DUE TO SUSTAINED LOSS OF BUS 24C (VR32. . . . . . 7.0SDC LOST DUE TO SUSTAINED LOSS OF BUS 24D (VR41. . . . . . 8.045. . . . . . . . . . . . 9.0RWST GRAVITY FEED MAKEUP TO THE RCS AND SG HEATREMOVAL53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0FOLLOWUP ACTIONS FOR LOSS OF SDC56. . . . . . . . . . . . . . . . . . . . . . ATTACHMENTS AND FORMSACS Component Elevation in Relation to Hot Leg Centerline"57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aotential Leakage Paths While On Shutdown Cooling"58. . . Aocation of SDC Piping for Alternate Temperature Monitoring"63. . . . . . . . . . . . . . . . . . . . . . . . . . . Aime to Boil Refuel Pool to Top of Fuel vs.Shutdown Time"64. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Attachment 5 ime to Core Uncovery Calculations"65. . . . . . . . . . . . . . . . . A""66. . . . . . . . . . . . . . . . . . . . . A"67. . . . . . . . . . . . . . . . . . . . . . Aealigning LPSI to Supply SDC and SFPC"68. . . . . . . . . . . A71. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 AOP 2572Revision 009-03Page 3 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW1.0PURPOSE 1 1.1.1 ObjectiveThis procedure provides actions for recovering from a partial or total loss of shutdown cooling.
1.2 Discussion
During SDC operation, there may not be flow past the loop RTDs. Core inlet and outlet temperatures are accurately measured during those conditions using SDC to RCS temperature, T351Y, and RCS to SDC temperature,T351X, respectively. The average of these indicators provides a temperaturethat is equivalent to the average RCS temperature in the core.
Containment Closure is established when all of the following conditions exist:The equipment door is closed and held in place by a minimum of four bolts.A minimum of one door in each airlock is closed.Each penetration providing direct access from the containment atmosphere to the outside atmosphere is either:Closed by a manual or automatic isolation valve, blind flange, or equivalent, orCapable of being closed under administrative control The use of the CS pump for decay heat removal does not meet the definition of an Operable SDC train (LCO 3.9.8). Therefore no fuel movement is permitted when a CS pump is aligned to SDC per this procedure.
1.3 Applicability
This procedure is applicable in MODEs 4, 5, 6 and Defueled.
Use of the CS pumps is limited to MODE 6 and Defueled.
2 2 AOP 2572Revision 009-03Page 4 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW2.0ENTRY CONDITIONS 1 2.Loss of Shutdown Cooling may be entered when ANY of the following conditions exist:ALLow or oscillating LPSI pump currentIncreasing RCS temperatureLow or decreasing RCS level on any of the following:ICC Reactor Vessel Level Monitoring SystemLCS level transmitterL AOP 2572Revision 009-03Page 5 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW3.0Initial Actions for Loss of SDC 3.INSTRUCTIONSCONTINGENCY ACTIONS C A U T I O N1.On a loss of SDC, immediate action must be taken to establishprior to initiation of RCS boiling.2.On a loss of AC power, Containment lighting may be degraded.Portable DC lighting may be used for Containment Closure activities.
3.1.___3.1IF fuel movement is in progress, NOTIFY RE to stop fuel movement.
3.2.___3.2OPEN placekeeper.
3.3.*3.3IF SDC is lost for greater than 15 minutes OR RCS temperature reaches 190F, PERFORM the following:a.NOTIFY Health Physics andCOORDINATE an evacuation of Containment.b.WHEN Containment evacuation is complete, ENSURE personnel airlock door
closed.3.4.___3.4REVIEW Shutdown Safety Assessment Sheet for most recent calculated time to boil.
3.5.___3.5NOTIFY designated personnel to establish Containment Closure prior to the most limiting of the following:RCS boiling2 hours from loss of SDC []2 AOP 2572Revision 009-03Page 6 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 3.6.___3.6REQUEST Health Physics perform the following:IF the SG primary sides and loop areas are occupied, EVACUATE personnel.MONITOR environmental conditions inside Containment.IF conditions degrade, NOTIFY Control Room.
3.7.___3.7ENSURE that all available CAR coolers are in service, as indicated by:CAR fan operatingRBCCW flow established C A U T I O NWith no SDC flow, T351X and T351Y do not provide an accurateindication of RCS temperature. Accurate indication is provided by UA, UUA, U(PPC).
3.8.___3.8IF available, MONITOR RCS level and temperature by use of PPC ICC level and temperature display, using
unheated junction thermocouples in contact with RCS inventory for
temperature indication.
3.9.___3.9Refer To MPAP06,ARs," and DETERMINE applicability.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 7 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW C A U T I O NOn a loss of all AC power, RWST gravity feed makeup to the RCS may bedesired. Due to RCS heatup and possible pressurization, use of this makeup
path is time sensitive.___3.10IF AC power is not available, CONSIDER using Section 9.0 for the following:RWST gravity feed makeup to RCSHeat removal by an available steam generator 3.10.___3.11DETERMINE cause of loss of SDCand PERFORM applicable action:IF lost due to loss of suction
- pressure, Go Toost Due to Loss of Suction Pressure or RCS Inventory"IF lost due to automatic tripping of running LPSI pump, Go Toost Due to Automatic Tripping ofRunning LPSI Pump"IF lost due to loss of bus 24C, Go Toost Due to Sustained Loss of Bus 24C (VRIF lost due to loss of bus 24D, Go Toost Due to Sustained Loss of Bus 24D (VRIF SDC flow is lost to SDC heatexchangers due to loss of power or
instrument air to SDC HX flow Go To Section 8.0, oss of Power INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 8 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 4.4.0SDC Lost Due to Loss of Suction Pressure or RCS Inventory
[]INSTRUCTIONSCONTINGENCY ACTIONS C A U T I O N If the running LPSI pump was lost due to a loss of suction pressure, the standby LPSI pump must not be started until RCS level restoration provides adequate suction pressure to avoid damage to the standby pump
and sustained loss of shutdown cooling.
NOTEWhen RCS level is at the centerline of the hot leg and the RCS is vented, a
minimum indicated suction pressure of 18 to 19 psig should be adequate to
operate a LPSI pump. The following instruments can be used:A" LPSI pump discharge pressure (C01/PPC)A" LPSI pump suction pressure (PPC) 4.1.___4.1DETERMINE RCS level using ALL available indications from the following list:ICC Reactor Vessel LevelMonitoring System (PPC)Loop WideRange RCS Level TransmitterLeg NarrowRange Level InstrumentCSoop Level Indicator (CCTV)
AOP 2572Revision 009-03Page 9 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 4.2.4.2.1IF SDC was lost due to the closure ofGo To step 4.10.___4.2 suction system isolation, and containment isolation, open.
4.3.___4.3ENSURE suction path from BAST orRWST is available to charging pumps.
4.4.___4.4OPEN the following:
C A U T I O N The combination of charging and HPSI pumps capable of injecting into theRCS is limited as specified in T/S LCO 3.4.9.3 as follows:MODE 4, and MODE 5 with all RCS cold leg temperature > 190F:Maximum of two charging pumps and one HPSI pump may becapable of injecting into the RCS; andTwo OPERABLE PORVS with a lift setpoint < 415 psia.MODE 5 with any RCS cold leg temperature <
190F, and MODE 6 either:Maximum of one charging pump may be capable of injecting intothe RCS; andTwo OPERABLE PORVS with a lift setpoint < 415 psia.
ORMaximum of two charging pumps and one HPSI pump may becapable of injecting into the RCS; andThe RCS is depressurized and an RCS vent of > 2.2 sq. inches.
4.5.___4.5START one charging pump.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 10 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 4.6.4.6.1IF operation of an additional chargingpump is required to restore RCSinventory, PERFORM the following:a.LOG entry into TSAS 3.4.9.3.Db.RESTORE charging pump availability.c.START one additional charging pump.___4.6IF the requirements of T/S 3.4.9.3 allow operation of two charging pumps, and two charging pumps are desired in operation START one additional charging pump.C A U T I O NFailure to closely monitor RCS level while filling may result in floodingfrom SG manways.
NOTEDesired RCS level for plant conditions:With nozzle dams OR SG manways installed: +15 inchesWith nozzle dams AND SG manways removed: +2 inchesWith maintenance opening in RCS: the level of the opening (Attachment 1 contains reference levels) 4.7.4.7.1IF operation of a HPSI pump isrequired to restore RCS inventory,PERFORM the following:a.LOG entry into TSAS 3.4.9.3.Db.RESTORE HPSI pump availability.c.OPEN available facility HPSI injection header stop:A" stop(Facility 1)stop (Facility 2)d.START available HPSI pump.___4.7IF desired and requirements of T/S 3.4.9.3 allow operation of HPSI pump,PERFORM the following:a.OPEN available facility HPSI injection header stop:A"stop (Facility 1)stop (Facility 2)b.START available HPSI pump.(continue) 3 3 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 11 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW4.7(continued)c.THROTTLE open all applicableHPSI injection valves as necessaryto raise and maintain RCS level andcontrol RCS temperature:If Facility 1 is used, HPSIA":oop 1Aoop 1Boop 2Aoop 2BIf Facility 2 is used, HPSIoop 1Aoop 1Boop 2Aoop 2Be.THROTTLE open all applicableHPSI injection valves as necessaryto raise and maintain RCS leveland control RCS temperature:If Facility 1 is used, HPSIA":oop 1Aoop 1Boop 2Aoop 2BIf Facility 2 is used, HPSI injection valvesoop 1Aoop 1Boop 2Aoop 2B 3 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 12 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW NOTE The reactor vessel must be vented for the gravity feed method of filling.
4.8.___4.8IF desired, PERFORM the following (gravity feed method for filling):a.suction system isolation, and
containment isolation, open.b.IFA" LPSI is the unaffected
- pump, PERFORM the following A" Safeguards Room):1)A" LPSI pump suction from SDC, open.2)A" LPSI pump suction from RWST.3)WHEN level isCLOSEA" LPSIpump suction from RWST.c.IF pump, PERFORM the followingoom):1)pump suction from SDC, open.2)THROTTLE open LPSI pump suction from RWST.3)WHEN level is CLOSE LPSI pump suction from RWST.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 13 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 4.9.___4.9Refer To OP 2310, PERFORM applicable actions to evacuate SDC suction piping.
4.10.___4.10DISPATCH operator to affected LPSI pump to check pump conditions.
4.11.___4.11CLOSE all LPSI injection valves:oop 1Aoop 1Boop 2Aoop 2B 4.12.___4.12Using applicable controller,PERFORM the following:a.b.
NOTE Cooling of the core takes precedence over LPSI pump considerations.
If the following conditions have been met, the affected LPSI pump may be
started without venting:Adequate NPSH is obtained upon RCS level recoverySDC suction leg piping is evacuated 4.13.___4.13IF ANY of the following conditions apply,Go To step 4.17:Unaffected LPSI pump is available to restore SDC flow.Affected LPSI pump will be used to restore SDC flow AND pump venting time will potentially
exceed expected time to core
boiling.INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 14 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 4.14.___4.14ESTABLISH direct communications between operators at LPSI pump andin Control Room.
NOTEV larger than the bubbles in carbonated water or soda.
STOP STOP W A R N I N GWater from the LPSI pump vent is potentially hot and may cause serious
burns.4.15.___4.15IFA" LPSI pump is affected, PERFORM the followingA" Safeguards Room):a.A" LPSI pump vent.b.A" LPSI pump vent.c.WHEN CLOSEA" LPSI pump
vent.4.16.___4.16IFPERFORM the followingoom):a.b.c.WHEN CLOSE vent.INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 15 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW NOTEWhen establishing RCS cooldown rate, optimum temperature response isC A U T I O N1.When establishing SDC flow while in reduced inventory, due to concerns regarding boron dilution and vortexing at the SDC suction, SDC flow must be limited to between 1,400 to 1,600 gpm.2.Caution should be used when reestablishing SDC heat exchanger flow due to the potential for water in the SDC heat exchangers to be much cooler than RCS temperature. Initiating flow slowly allows
temperatures to equalize.
4.17.___4.17ESTABLISH SDC flow as follows:a.ENSURE BOTH of the following are open:system isolation containment isolationb.SDC HX flow control, closed.c.CRACK open ONE LPSIinjection Valve:oop 1Aoop 1Boop 2Aoop 2B (continue)
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 16 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW4.17(continued)d.ENSURE LPSI pump suction pressure is at least 18 psig, as indicated on LPSI pump discharge pressure instrument.e.START ONE LPSI pump.f.ENSURE the following:SDC flow is stable with no significant oscillations.LPSI pump motor amperage is stable.Associated LPSI pump annunciators are not lit.g.IF in reduced inventory, slowly THROTTLE open LPSI injection valves, to raise SDC total flow to between 1,400 and 1,600 gpm:oop 1Aoop 1Boop 2Aoop 2Bh.IF not in reduced inventory, slowly THROTTLE open LPSI injection valves, to raise SDC total flow between 3,500 and
4,000 gpm:oop 1Aoop 1Boop 2Aoop 2B (continue)
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 17 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW4.17(continued)i.WHEN establishing cooldown, Refer To SP 2602B, ransient Temperature, PressureVerification," and PERFORM the following:MONITOR RCS cooldown rate using T351Y.ENSURE system response is within cooldown limits.j.
maintain desired cooldown rate.k.controller, AND RBCCW outlet manual isolations (as required) to maintain desired cooldown rate:RBA" RBCCW outlet manual isolationRB manual isolationl.ENSURE RBCCW flows do not exceed the following:Total applicable RBCCW header flow of 8,000 gpmA single SDC heat exchangerRBCCW flow of 4,800 gpm INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 18 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 4.18.___4.18PERFORM the following to determine source of leakage:Refer To Attachment 2,otential Leakage Paths While
on Shutdown Cooling," and ATTEMPT to identify source of
leakage.OBSERVE the following parameters for indications of RCS leakage:Containment sump levelRWST levelPDT level and pressureQuench tank level and pressureEquipment drain sump tank levelSFP levelPrimary sample flows (primary sample sink)Clean Waste Panel Indications (C63)Aerated Waste Panel Indications (C60)IF leaks are identified, ATTEMPT to isolate source of
leakage.INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 19 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 4.19.*4.19WHEN desired RCS level is attained, AND leakage has been isolated,PERFORM the following:a.STOP running HPSI pump andPLACE handswitch in Tb.STOP all charging pumps.c.CLOSE applicable HPSI injection header stop: HPSI Header A Stopd.CLOSE charging header isolations:e.IF required, CLOSE applicable HPSI injection valves:If Facility 1 is used, HPSIInjection Valves Header A:oop 1Aoop 1Boop 2Aoop 2BIF Facility 2 is used, HPSIInjection Valves Header B:oop 1Aoop 1Boop 2Aoop 2Bf.VERIFY appropriate administrative controls are in place to comply with TS 3.4.9.3.
3 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 20 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 4.20.*4.20MONITOR for the following:Low or oscillating SDC flowLow or oscillating LPSI pump motor currentRising RCS temperatureLow or decreasing RCS levelLPSI pump annunciators lit 4.21.4.21.1I F the loss of suction pressure damaged the LPSI pump(s) to the point where they cannot support SDCoperations, PERFORM the following:a.PERFORM action in Section 4.0 to fill and vent the suction header.b.Go To Section 5.0 and PLACE a CS pump in service.
- 4.21IF at any time, one or more of the conditions specified in step 4.20 indicate loss of suction pressure to the running LPSI pump, PERFORM the following:a.STOP running LPSI pump.
b.Go To step 4.3 to commenceRCS fill.4.22.4.23.___4.22IF RCS pressure is stable AND RCS temperature is less than 200F and stable, STOP Containment Closure
activities.
4.24.___4.23Go To Section 10.0.
2 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 21 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 5.5.0SDC Lost Due to Tripping of Running LPSI Pump INSTRUCTIONSCONTINGENCY ACTIONS NOTE1.This section assumes a running LPSI pump breaker trip without a concurrent loss of power to the associated bus.2.Obtaining reference positions of SDC flow control valves may be helpful during SDC restoration.3.If diverting additional flow through SDC heat exchangers is required, 5.1.___5.1Using applicable controller,PERFORM the following:a.RECORD output of the following SDC flow controllers:b.Control Valve c.otal FlowControl Valve, full open
5.2.___5.2CLOSE all LPSI Injection Valves:oop 1Aoop 1Boop 2Aoop 2B AOP 2572Revision 009-03Page 22 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 5.3.___5.3IF SDC was supplying only theRCS/Refuel Pool, CRACK open oneLPSI Injection Valve:VS" LOOP 1AVS" LOOP 1BVS" LOOP 2AVS" LOOP 2B 5.4.___5.4IF SDC was supplying both the SpentFuel Pool and the RCS/Refuel Pool,PERFORM the following:a.RECORD position of RW-15,RW-15 percent open: _______b.THROTTLE RW-15 toapproximately 10% open.c.CRACK open one LPSI InjectionValve:VS" LOOP 1AVS" LOOP 1BVS" LOOP 2AVS" LOOP 2B 2 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 23 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 5.5.5.5.1IF the standby LPSI pump is not available, PERFORM the following:a.IF time permits, EVALUATE cause of LPSI pump
trip as follows:1)DISPATCH operator toapplicable 4160 VAC pump
breaker to obtain protective
relay status:A" LPSI pump: A3092)DISPATCH operator toapplicable ESF room to
observe pump condition.b.IF SM permission is obtained, START LPSI pump that tripped.___5.5IF available, START standby LPSI pump.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 24 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW C A U T I O NPrior to utilizing a CS pump for SDC, the RCS heat removal rate andassociated SDC flow must be considered. Maximum SDC flow through any CS pump is limited to 1700 gpm. Additionally, the RWST suction
header must be filled and vented in order to align the associated CS pump to the RCS. The applicable facility ECCS suction flowpath from the RWST is isolated.
5.6.___5.6IFA" CS Pump for SDC as follows:a.COMPLETE A" CS pump alignment verification (Attachment 6).b.VERIFY one train of SFPC in service in accordance with uel Pool Cooling and Purification System."c.ENSURE suction pressure is greater than or equal to 18 psig.d.STARA" CS pump.
5.7.___5.7IF SDC as follows:a.alignment verification (Attachment 7).b.VERIFY one train of SFPC in service in accordance with uel Pool Cooling and Purification System."c.ENSURE suction pressure is greater than or equal to 18 psig.d.STAR 2 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 25 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 5.8.___5.8IF no LPSI or CS pumps are available, PERFORM the following:a.Refer ToWSTGravity Feed Makeup to the RCSAnd SG Heat Removal," for alternate methods of heat
removal.b.VERIFY one train of SFPC in service in accordance withuel Pool Cooling and Purification System."c.WHEN either LPSI pump becomes available, PERFORM the following:1)IF a SFPC train was placed in service in accordance with step 5.8.b., Refer To uel Pool Cooling and PurificationSystem," and REMOVE SFPC from service.2)VERIFY system alignment supports use of the LPSI
pump.3)ENSURE suction pressure greater than 18 psig.4)START applicable LPSI pump.d.WHEN either CS pump becomesavailable, PERFORM the following:1)VERIFY system alignment supports use of the CS pump.2)ENSURE suction pressure greater than 18 psig.3)START applicable CS pump.
2 2 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 26 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW C A U T I O N1.When establishing SDC flow while in reduced inventory, due to concerns regarding boron dilution and vortexing at the SDC suction, SDC flow must be limited to between 1,400 to 1,600 gpm.2.SDC flow through any one LPSI pump must be limited to a maximum of 4,000 gpm.3.SDC flow through any one SDC heat exchanger must be limited to amaximum of 4,800 gpm.4.SDC flow through only one CS pump must be limited to a maximum of 1700 gpm.5.9.___5.9IF SDC was supplying flow to only theRefuel Pool, PERFORM the following:a.IF the RCS is in reducedinventory, PERFORM the following:1)IF a LPSI pump is in service, THROTTLE flow 1400 to
1600 gpm.2)IF a CS pump is in service,PERFORM the following:a)THROTTLE flow 1400 to 1600 gpm.b)MONITOR for indications of cavitation.
2 2 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 27 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW5.9(continued)b.IF the RCS is not in reducedinventory, PERFORM the following:1)IF a LPSI pump is in service, THROTTLE flow 3500 to
4000 gpm.2)IF a CS pump is in service, THROTTLE flow 1650 to
1700 gpm.5.10.___5.10IF SDC was supplying both the SFPand Refuel Pool, PERFORM the following:a.IF a LPSI pump in service,PERFORM the following:1)THROTTLE the following valves to obtain previous flow
splits:VLVS" LOOP 1AVLVS" LOOP 1BVLVS" LOOP 2AVLVS" LOOP 2B2-R SFPC Stop" (continue) 2 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 28 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW5.10(continued)2)CHECK pressure at2-RWPurification Return Sample Stop," less than 30 psig.2)IF pressure at 2-RW-66 is greater than 30 psig, PERFORM the following:a.THROTTLE 2-RW-15,
obtain less than 30 psig at 2-RW-66.b.CONTACT Engineering for additional guidance on decay
heat removal.Table 1.0Fuel Assemblies Flow splits with SFPC in service Flow splits with SFPC not in serviceOff-LoadedFlow to RFPFlow to SFPFlow to RFPFlow to SFP0-8017000125045081-1701400300750950171-21711006004001300 5.11.b.IF a CS pump is in service,PERFORM the following:1)THROTTLE the followingvalves to obtain Table 1.0
flow splits:VLVS" LOOP 1AVLVS" LOOP 1BVLVS" LOOP 2AVLVS" LOOP 2B2-R SFPC Stop" (continue) 2 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 29 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW5.10(continued)2)CHECK pressure at2-RWPurification Return Sample Stop," less than 30 psig.2)IF pressure at 2-RW-66 is greater than 30 psig, PERFORM the following:a.THROTTLE 2-RW-15,
obtain less than 30 psig at 2-RW-66.b.CONTACT Engineering for additional guidance on decay
heat removal.
C A U T I O NCaution should be used when reestablishing SDC heat exchanger flow, due to the potential for water in the SDC heat exchangers to be much cooler than RCS temperature. Initiating flow slowly allows temperatures to
equalize.5.12.___5.11WHEN establishing cooldown, Refer ToransientTemperature, Pressure Verification,"and PERFORM the following:MONITOR RCS cooldown rate using T351Y.ENSURE system response is within cooldown limits.
5.13.___5.12 Controller, to establish and maintain desired cooldown rate.
5.14.___5.13IF additional flow through SDC heat exchangers is required, 2 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 30 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 5.15.5.14.1IF pressure at 2-RW-66 is greater than 30 psig, PERFORM the following:a.THROTTLE 2-RW to SFPC Stop," to obtain less than 30 psig at 2-RW-66.b.CONTACT Engineering for additional guidance on decay
heat removal.___5.14CHECK pressure at 2-RW-66,W Purification Return Sample Stop," less than 30 psig.
NOTEWhen establishing RCS cooldown rate optimum temperature response will5.16.___5.15 Controller, AND the RBCCW outlet manual isolations (as required) to maintain the desired cooldown rate:RBA" RBCCW Outlet Manual IsolationRB Manual Isolation 5.17.___5.16ENSURE RBCCW flows do not exceed the following:Total applicable RBCCW header flow of 8,000 gpmA single SDC heat exchangerRBCCW flow of 4,800 gpm 2 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 31 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW NOTE2-SI-306 has designed leakby that diverts flow around the SDC heat exchangers and could challenge heat removal with CS pumps supplying
SDC.5.18.___5.17IF a CS pump is in service on SDC and sufficient cooling cannot be obtained with 2-SI-306 closed, CLOSE the applicable LPSI to SDC
heat exchanger isolation valve:2-SI-452, LPSI PumpA" SDC Heat
Exchanger2-SI-453, LPSI Pump
Exchanger 5.19.___5.18REPEAT steps 5.12 through 5.17 asneeded to control RCS temperature.
5.20.___5.19WHEN ready to shift SDC from a CS pump to a LPSI pump, PERFORMAealigning LPSI to Supply SDC and SFPC." 5.21.___5.20WHEN RCS pressure is stable AND RCS temperature is less than 200F and stable, STOP Containment Closure
activities.
5.22.___5.21Go To Section 10.0.
2 2 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 32 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 6.6.0SDC Lost Due to Sustained Loss of Bus 24C (VR INSTRUCTIONSCONTINGENCY ACTIONS C A U T I O NIf SDC is restored prior to restoration of VRnormal temperature monitoring with T351Y will be unavailable to perform SP 2602B, ransient Temperature, Pressure Verification." Although SDC restoration is preferably performed with VR
cooling takes precedence over establishing normal or alternate
temperature monitoring.
NOTEThis section assumes a loss of power to buses 24C, 22E and VRoss of
power will have the following effects:A" LPSI pumpThe inability to close two LPSI injectionLoss of power to the following SDC instrumentation:T351X, RCS to SDCT351Y, SDC to RCSF6043, SDC HX A RBCCW FlowT6051, SDC HX A RBCCW TemperatureF3023, SDC HX A SDC FlowT303X, SDC HX A SDC TemperatureF312, LPSI Flow to Loop 1AF322, LPSI Flow to Loop 1BTR351, SDC Temperature Recorder 6.1.6.1.1Refer Tooss of Power applicable.___6.1PERFORM the following:a.OBSERVE and MARK (continue)
AOP 2572Revision 009-03Page 33 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW6.1(continued)b.CLOSEc.CLOScontrol (FIC 306).C A U T I O NIf ICC temperature monitoring is unavailable, remote RCS temperaturemonitoring may be lost. Once a LPSI pump is operating, RCS temperatures must be monitored using T351X and T351Y, or if VR deenergized, by handheld infrared temperature gun measurements on piping adjacent to the temperature elements for T351X and T351Y.
6.2.___6.2IF available, MONITOR RCS level andtemperature by use of Control Room PPC ICC level and temperature
display using unheated junction thermocouples in contact with RCS
inventory.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 34 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW C A U T I O N1.
as soon as possible after starting the LPSI pump.2.When establishing SDC flow while in reduced inventory, due to concerns regarding boron dilution and vortexing at the SDC suction, SDC flow must be limited to between 1,400 to 1,600 gpm.3.SDC flow through any one LPSI pump must be limited to a maximum of 4,000 gpm.4.SDC flow through any one SDC heat exchanger must be limited to amaximum of 4,800 gpm.
6.3.6.3.1IF neither LPSI pump is available, PERFORM the following:a.Refer To ONE of the following procedures as applicable, and
RESTORE bus 24C or 24D (bus
24C preferred):Aoss of AllAC Power During
Shutdown Conditions"Aoss ofVital 4.16 KV Bus 24C"b.CONTINUE to monitor RCS temperature by any means
available.c.Refer ToWSTGravity Feed Makeup to the RCS And SG Heat Removal," for
alternate methods of heat
removal.d.WHEN either LPSI pump becomes available, ENSURE
adequate suction pressure., (18 to 19 psig) and START applicable
LPSI pump.___6.3IF bus 24D is energized ANDPERFORM the following:a.aligned for SDC.b.STAR c.
not to exceed the followingapplicable SDC system flow limits:Reduced inventory SDC total flow between 1,400
and 1,600 gpmNormal (1 pump) operation SDC total flow
between 3,500 and 4,000
gpmd.Refer To Aossof Vital 4.16 KV Bus 24C,"
and RESTORE bus 24C, while continuing in this
procedure.e.Go To step 6.5.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 35 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 6.4.___6.4Slowly Controller, fully, not to exceed the following applicable SDC system flow limits:Reduced inventory SDC total flow between 1,400 and 1,600
gpmNormal (1 pump) operation SDC total flow between 3,500 and
4,000 gpm 6.5.___6.5IF, at any time, RCS temperature is greater than 200 5 F and rising OR indications of RCS boiling are
- observed, Go To step 6.9 to commence cooling.
6.6.___6.6IF bus 24C AND VRGo To step 6.9.
C A U T I O N A handheld infrared temperature gun should be used to allow temperature
readings to be taken at a distance from the piping, and the operator taking
readings should wait in a low dose area between temperature readings.
6.7.___6.7ESTABLISH alternate SDC temperature monitoring as follows:a.OBTAIN a handheld infraredtemperature gun from Control Room.(continue)
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 36 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW6.7(continued)b.Refer To Attachment 3,ocation of SDC Piping forAlternate Temperature Monitoring," and DISPATCH an operator with a
handheld infrared temperature
gun to applicable SDC piping 6)c.ESTABLISH communications between operator at SDC pipingand Control Room.d.MONITOR SDC piping temperature as directed byControl Room.e.WHEN normal SDC temperature monitoring is restored, RELEASE operator.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 37 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 6.8.___6.8ALIGN alternate supply to VR from B32 as follows:a.IF bus 24A is deenergized AND bus 24B is energized, PERFORM the following to 1)PLA 22C/22D" to 2)ATTEMPT to close B0313,3)PLACE SYN SEL."b.WHEN B32 is energized, PERFORM the following:1)OPEN and LOCK breakerTING TRANS #1" (VR2)UNLOCK and CLOSE breaker B3246, ALT FDR FOR UA (VR3)On transfer switch RS1,OBSERVE the following:AD" lamp litLOAD" lamp not lit 1 INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 38 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW NOTE1.ransient Temperature, Pressure Verification" directs using T351Y to monitor heatup and cooldown rates. Although no provision
exists to use any other temperature indication for this purpose, an
attempt should be made to apply heatup and cooldown limits when
using any alternate temperature indication. This procedure later
directs engineering evaluation and analyses to determine the impact of this event and comply with the applicable Technical Specification.2.When monitoring SDC to RCS piping temperature by handheld infrared temperature gun measurement, a delay in temperature
response can be expected with any change in SDC heat removal rate
due to pipe wall thickness.
6.9.___6.9WHEN establishing cooldown, Refer ToransientTemperature, Pressure Verification,"and PERFORM one of the following:IF VRMONITOR RCS cooldown using
T351Y.IF time permits, MONITOR cooldown using
handheld infrared temperature
gun at location shown onAttachment 3.IF VR not restored ANDRCS boiling is imminent, MONITOR RCS cooldown with
any available instrumentation.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 39 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW C A U T I O NCaution should be used when reestablishing SDC heat exchanger flow due to the potential for water in the SDC heat exchangers to be much cooler than RCS temperature. Initiating flow slowly allows temperatures to
equalize.6.10.___6.10 Controller, to establish and maintain desired cooldown rate.
6.11.___6.11IF additional flow through SDC heat exchangers is required, slowly otalFlow Control Valve NOTE1.When establishing RCS cooldown rate, optimum temperature response isachieved by maintaining between 35 and 60% open.2.Loss of power may have reduced RBCCW flow supporting SDC heat removal.6.12.___6.12 Controller, AND RBCCW outlet manual isolations, if required, to maintain the desired cooldown rate:RBA" RBCCW outlet manual isolationRB manual isolation 6.13.___6.13ENSURE RBCCW flows do not exceed the following:Total applicable RBCCW header flow of 8,000 gpmA single SDC heat exchangerRBCCW flow of 4,800 gpm 6.14.___6.14REPEAT steps 6.10 through 6.13 asneeded to control RCS temperature.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 40 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 6.15.___6.15IF necessary to provide additional SDC heat removal, Refer To Cooling," as needed and
CONSIDER alignment changes to
SDC heat exchangers.
6.16.___6.16WHEN RCS pressure is stable AND RCS temperature is less than 200F and stable, STOP Containment Closure
activities.
6.17.___6.17Go To Section 10.0.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 41 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 7.7.0SDC Lost Due to Sustained Loss of Bus 24D (VR INSTRUCTIONSCONTINGENCY ACTIONS NOTEThis section assumes a loss of power to buses 24D, 22F and VRoss of power will have the following effects:The inability to remotely close two LPSI injection valves.Loss of power to the following SDC instrumentation:F6042, SDC HX B RBCCW FlowT6056, SDC HX B RBCCW TemperatureF3024, SDC HX B SDC FlowT303Y, SDC HX B SDC TemperatureF332, LPSI Flow to Loop 2AF342, LPSI Flow to Loop 2B 7.1.7.1.1Refer Tooss of Power applicable.___7.1PERFORM the following:a.OBSERVE and MARK b.control.c.
7.2.___7.2IF available, MONITOR RCS level and temperature by use of PPC ICC level and temperature display using
unheated junction thermocouples in contact with RCS inventory.
AOP 2572Revision 009-03Page 42 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW C A U T I O N1.
as soon as possible after starting the LPSI pump.2.When establishing SDC flow while in reduced inventory, due to concerns regarding boron dilution and vortexing at the SDC suction, SDC flow must be limited to between 1,400 to 1,600 gpm.3.SDC flow through any one LPSI pump must be limited to a maximum of 4,000 gpm.4.SDC flow through any one SDC heat exchanger must be limited to amaximum of 4,800 gpm.
7.3.7.3.1IF neither LPSI pump is available, PERFORM the following:a.Refer To ONE of the following and RESTORE bus 24D:Aoss of AllAC Power During
Shutdown Conditions"AOP 2502D, "Loss ofVital 4.16 KV Bus 24D"b.CONTINUE to monitor RCS temperature.c.Refer To Section 9.0, WST Gravity Feed Makeup to the RCS and SG Heat Removal,"
for alternate methods of heat
removal.d.WHEN either LPSI pump becomes available, START applicable LPSI pump and CONTINUE with this
procedure.___7.3IF bus 24C is energized ANDLPSI pump is available, PERFORM the following:a.ENSURE A" LPSI pump aligned for SDC.b.STARA" LPSI pump.
c.Slowly OPEN controller, fully, not to exceedthe following applicable SDC system flow limits:Reduced inventory SDC total flow between 1,400
and 1,600 gpmNormal (1 pump) operation SDC total flow
between 3,500 and 4,000
gpmd.Refer To AOP 2502D, "Lossof Vital 4.16 KV Bus 24D," and RESTORE bus 24D, while continuing in this
procedure.e.Go To step 7.5.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 43 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 7.4.___7.4Slowly controller, fully, not to exceed the following applicable SDC system flow limits:Reduced inventory SDC total flow between 1,400 and 1,600
gpmNormal (1 pump) operation SDC total flow between 3,500 and
4,000 gpm 7.5.___7.5WHEN establishing cooldown, Refer ToransientTemperature, Pressure Verification,"and PERFORM one of the following:MONITOR RCS cooldown using T351Y.ENSURE system response is within cooldown limits.
C A U T I O NCaution should be used when reestablishing SDC heat exchanger flow due to the potential for water in the SDC heat exchangers to be much cooler than RCS temperature. Initiating flow slowly allows temperatures to
equalize.7.6.___7.6 maintain desired cooldown rate.7.6.1Refer Tooss of Power 7.7.___7.7IF additional flow through SDC heat exchangers is required, slowly 7.7.1Refer Tooss of Power INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 44 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW NOTEWhen establishing RCS cooldown rate optimum temperature response is7.8.___7.8 Controller, AND the RBCCW outlet manual isolations, as required, to maintain the desired cooldown rate:RBA" RBCCW outlet manual isolationRB manual isolation 7.9.___7.9ENSURE RBCCW flows do not exceed the following:Total applicable RBCCW header flow of 8,000 gpmA single SDC heat exchangerRBCCW flow of 4,800 gpm 7.10.___7.10REPEAT steps 7.6 through 7.9 asneeded to control RCS temperature.
NOTELoss of power may have reduced RBCCW flow supporting SDC heat removal.7.11.___7.11IF necessary to provide additional SDC heat removal, Refer To OP 2310,
CONSIDER alignment changes to
SDC heat exchangers.
7.12.___7.12WHEN RCS pressure is stable AND RCS temperature is less than 200F and stable, STOP Containment Closure
activities.
7.13.___7.13Go To Section 10.0.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 45 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 8.8.0Loss of P INSTRUCTIONSCONTINGENCY ACTIONS NOTE1.Loss of power or air to SDC flow control valves has the following affect: fails closed2.Loss of VA 3.flow limit stop position) when diverting additional flow through SDC
heat exchangers is required.4.Obtaining reference positions of SDC flow control valves may behelpful during SDC restoration. If a loss of VA
reference positions are only available as archive data in the PPC (PPC
analog points 2SI657 and 2SI306).
8.1.___8.1OBSERVE applicable controllers or PPC analog points to obtain a reference position for SDC flow control valves:
archive PPC data for 2SI306 archive PPC data for 2SI657 8.2.___8.2For the failed valve(s), ADJUST the controller output to match actual valve position.FIC-306HIC-3657 2 AOP 2572Revision 009-03Page 46 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW NOTEWhen establishing RCS cooldown rate, optimum temperature response is8.3.___8.3IF onlyPERFORM the following:a.WHEN establishing cooldown, Refer to SP 2602B, ransient Temperature, Pressure Verification," and PERFORM the following:MONITOR RCS cooldown rate using T351Y.ENSURE system response is within cooldown limits.b.ADJUST RCS temperature, as indicated on T351Y, as follows:1)
and maintain desired
cooldown rate.2)AND SDC HX RBCCW outlet manual isolations (as required) to maintain
desired cooldown rate:RBA"RBCCW outlet
manual isolationRBRBCCW outlet
manual isolation (continue)
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 47 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW8.3(continued)3)ENSURE RBCCW flowsdo not exceed the following:Total applicableRBCCW header flow
of 8,000 gpmA single SDC heat exchanger RBCCW
flow of 4,800 gpmc.REPEAT step 8.3.b. as needed tocontrol RCS temperature.d.IF desired temperature control is not obtained, PERFORM one or more of the following as required:Refer To OP 2310, START an additional LPSI
pump on SDC.IF RBCCW is not available toa SDC heat exchanger, ISOLATE the applicable SDCheat exchanger as follows:A" SDC heat exchanger
discharge to SDC.
discharge to SDC.Refer To step 8.9 and achieve desired temperature
control.e.WHEN desired temperature control is obtained, Go To step 8.10.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 48 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW NOTELoss of power or air may have caused RBCCW components to shiftposition, thereby diverting RBCCW flow from SDC heat exchangers; for
instance, CAR cooler supply valves fail open due to loss of air or power.
8.4.___8.4DETERMINE if loss of power or airaffected other RBCCW loads.
8.5.___8.5IF loss of power or air causedRBCCW flow to divert from SDC heat exchangers, PERFORM the following, as needed:a.OBSERVE previous RBCCW flow to SDC heat exchangers in
PPC archive:F6043, SDC HX A RBCCW flowF6042, SDC HX B RBCCW flowb.As needed, manually ISOLATE RBCCW components to divert flow to SDC heat exchangers to obtain values at or near those in step 8.5.a. to include, but not limited to, closing the CAR cooler manual
isolations.
NOTEAA" LPSI pumps.
8.6.___8.6OBTAIN a 2 inch wrench to rotate 8.7.___8.7ESTABLISH direct communicationsA" ESFRoom) and Control Room.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 49 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW C A U T I O NCare should be used when establishing SDC heat exchanger flow due to the potential for water in the SDC heat exchanger to be much cooler than RCS temperature. Initiating flow slowly allows temperatures to equalize.
NOTE1.counterclockwise rotation of the handwheel closes the valve and clockwise rotation of the handwheel opens the valve.2.When establishing RCS cooldown rate, optimum temperature response isachieved by maintaining between 35 and 60% open.
8.8.___8.8IFPERFORM the following:a.WHEN establishing cooldown, Refer to SP 2602B,ransient Temperature, Pressure Verification,"
and PERFORM the following:MONITOR RCS cooldown rate using T351Y.ENSURE system response is within cooldown limits.b.PERFORM the following to take A" ESF Room):1)UNLOCK the manual handwheel on valve.2)CLOSE instrument air supply valve and
VENT valve operator.3)LOOSEN stem hex nut as required to allow stem
movement.4)ROTA handwheel as directed bythe Control Room.(continue)
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 50 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW8.8(continued)c.ADJUST RCS temperature, as indicated on T351Y, as follows:1)Slowly ROTATE handwheel to establish and
maintain desired cooldown
rate.2)AND the SDC HXRBCCW outlet manual isolations as required to
maintain desired
cooldown rate:RBA" RBCCW outlet
manual isolationRBmanual isolation3)ENSURE RBCCW flows do not exceed the following:Total applicableRBCCW header flow
of 8,000 gpmA single SDC heat exchanger RBCCW
flow of 4,800 gpm (continue)
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 51 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW8.8(continued)d.IF additional temperature control is needed, PERFORM one or more of the following as required:Refer To OP 2310, START an additional LPSI
pump on SDC.IF RBCCW is not available to a SDC heat exchanger, ISOLATE applicable SDC heat exchanger as follows:A" SDC heat exchanger
discharge to SDC.
discharge to SDC.Refer To step 8.9 and achieve desired temperature
control.e.WHENposition are complete, TIGHTEN stem hex nut against handwheel body.f.IF desired temperature control is not obtained, Go To step 8.8.c.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 52 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW NOTEcounterclockwise rotation of the handwheel closes the valve and clockwise rotation of the handwheel opens the valve.
8.9.___8.9As necessary, ESTABLISH locala.ESTABLISH communications between operators at the valve A" ESF Room) and Control Room.b.CLOSE instrument air supply for.c.OPEN petcock on instrument air supply pressure regulator and control, valve operator.d.UNLOCK and REMOVE chain from manual handwheel.e.ROTATE manual handwheel counterclockwise and ALIGN holes in outer shaft with hole in inner shaft.f.INSERT the pin into shaft holes.g.control, valve position indicator on the manual actuator is at throttled open position.h.IF desired to manually operate handwheel as directed by theControl Room.
8.10.___8.10WHEN recovery from manual operations is desired, PERFORM actions specified by the SM/US.INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 53 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 9.9.0RWST Gravity Feed Makeup to the RCS and SG Heat Removal INSTRUCTIONSCONTINGENCY ACTIONS C A U T I O N1.On a loss of all AC power, RWST gravity feed makeup to the RCS maybe desired. Due to RCS heatup and possible pressurization, use of this
makeup path is time sensitive.2.Failure to closely monitor RCS level while filling may result in flooding from SG manways.
9.1.___9.1DETERMINE whether RCS makeupby gravity feed from RWST is desired.
9.2.___9.2ENSURE adequate RWST inventoryis available for RCS makeup.
9.3.___9.3IFA" LPSI pump suction path, PERFORM the followingA" Safeguards Room):a.A" LPSI pump suction from SDC, open.b.As necessary, A" LPSI pump suction from RWST, to makeup for RCS
9.4.___9.4IF suction path, PERFORM the following oom):a.pump suction from SDC, open.b.As necessary, pump suction from RWST, to makeup RCS inventory.
AOP 2572Revision 009-03Page 54 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW NOTEremoval path by reflux boiling if primary manways are installed. However, verification of heat removal is more difficult.
9.5.___9.5REVIEW the following plant conditions and DETERMINE whether a steam generator is available as heat removal
path:SG corrected levelPlant outage work status and effect on SG and Main Steam
System componentsSG primary manways statusSG secondary manways statusNozzle dam installationStatus of AFW System to feed SGs INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 55 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW C A U T I O NIf SG secondary manways are not installed, the atmospheric dump valves must not be opened because a direct path from containment atmosphere to outside atmosphere will be created.
9.6.___9.6IF a steam generator is available for heat removal, PERFORM the following:a.Refer ToAuxiliaryFeedwater System," and PERFORM necessary actions to
establish a feed source to the available SG.b.MAINTAIN SG corrected level greater than 10%.c.OPEN applicable atmospheric dump valve fully:
atmospheric dump atmospheric dumpd.Refer To SP 2602B, ransient Temperature, Pressure Verification," and
MONITOR applicableparameters for effective SG heatremoval and RCS temperature
stability.
INSTRUCTIONSCONTINGENCY ACTIONS AOP 2572Revision 009-03Page 56 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 10.10.0F]INSTRUCTIONSCONTINGENCY ACTIONS 10.1.___10.1As required, Refer To SP 2602B,ransient Temperature, PressureVerification," and PERFORM applicable actions.
10.2.___10.2IF SDC can not be restored,PERFORM the following to determine time to core uncovery:a.REVIEW Shutdown Safety Assessment Sheet for most recent
calculated time to boil.b.IF RCS is in a refueling condition with refuel pool full, Refer To Attachment 4, ime to Boil Refuel Pool to Top of Fuel vs. Shutdown Time," and DETERMINE time to boil the refuel pool to top of fuel.c.Refer To Attachment 5, ime to Core Uncovery
Calculations," and CALCULATE time to core
uncovery.10.3.___10.3ENSURE RCS temperature is lowering within cooldown limits.
10.4.___10.4REQUEST Engineering Department perform the following:EVALUATE impact of any RCS heatup or cooldown resulting
from loss of shutdown cooling.IF required, PERFORM thermal stress
evaluation.
10.5.___10.5EVALUTE resumption of fuel movement2 RCS Component Elevation in Relation to Hot Leg Centerline(Sheet 1 of 1)AOP 2572Revision 009-03Page 57 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEWSG Cold Leg Wet Nozzle Dam (Bottom)+6.5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SG Hot Leg Wet Nozzle Dam (Bottom)+9.5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SG Manway (Bottom)+11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bottom of RCP Seal Package+20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Top of RCP Seal Package+52. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reactor Vessel Flange+79.5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Potential Leakage Paths While On Shutdown Cooling(Sheet 1 of 5)AOP 2572Revision 009-03Page 58 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW1.POTENTIAL LEAKAGE PATHS TO PDTCold leg drains to PDT (loop 1):Through RThrough RCold leg drains to PDT (loop 2):Through RThrough RHot leg drains to PDT (loop 1), through RRRPressurizer spray line drains to PDT:Through RThrough RSDC suction relief to PDT,Charging and letdown drains to PDT (Exists when system is isolated):Through letdown drains to PDT,Through auxiliary spray line drain to PDTThrough charging line drain to PDTThrough charging line drain to PDT Potential Leakage Paths While On Shutdown Cooling(Sheet 2 of 5)AOP 2572Revision 009-03Page 59 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEWCheck valve leakage drains to PDT 2.POTENTIAL LEAKAGE PATHS TO QUENCH TANK:Pressurizer Safety Valves to quench tankThrough R(local)Through R(local)PORVs to quench tank:Through R(local)Through R(local)Check valve leakage drains to quench tank Potential Leakage Paths While On Shutdown Cooling(Sheet 3 of 5)AOP 2572Revision 009-03Page 60 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW3.POTENTIAL LEAKAGE PATHS TO SAMPLE SYSTEMNo. 1 hot leg to sample system through RRPressurizer surge line to sample system through R(local),and RPressurizer steam space to sample system through RR(primary sample sink)Safety injection header discharge to sample system (primary sample sink) (primary sample sink)4.POTENTIAL LEAKAGE PATHS TO EDSTSDC suction relief to EDSTSDC heat exchanger drain to EDSTSDC heat exchanger discharge relief to Equipment Drain Sump TankSDC System discharge header relief to EDSTLetdown heat exchanger relief valve discharge drain to EDST (local) Potential Leakage Paths While On Shutdown Cooling(Sheet 4 of 5)AOP 2572Revision 009-03Page 61 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW5.POTENTIAL LEAKAGE PATHS TO NITROGEN SYSTEMPressurizer spray line to nitrogen header through R(local)6.POTENTIAL LEAKAGE PATHS TO SFP COOLING SYSTEM (The following valves may be open to supplement SFPC)7.POTENTIAL LEAKAGE PATHS TO LETDOWN SYSTEM (The following valves are normally open for Excess Letdown)LSDC return to L8.POTENTIAL LEAKAGE PATHS TO PASS SYSTEMSafety injection pump discharge to PA9.POTENTIAL LEAKAGE PATHS TO RWSTSafety injection pump suction from RWSTLPSI pump minimum flow recirculation to RWSTSDC recirculation to RWST Potential Leakage Paths While On Shutdown Cooling(Sheet 5 of 5)AOP 2572Revision 009-03Page 62 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW10.POTENTIAL LEAKAGE PATH TO RBCCW SYSTEMSDC heat exchanger(s) via a tube leak11.ADDITIONAL PURIFICATION/EXCESS LETDOWN TO SAMPLE SYSTEM sink) Location of SDC Piping for Alternate Temperature Monitoring(Sheet 1 of 1)AOP 2572Revision 009-03Page 63 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW6 Auxiliary Building Degasifier Area
DEGASIFIER DEGASIFIER PUMPSSDC TO RCS (12")SDC FROM RCS (14")
MONITOR HERE Time to Boil Refuel Pool to Top of Fuel vs. Shutdown Time(Sheet 1 of 1)AOP 2572Revision 009-03Page 64 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 1 2 3 4 5 6 7 8 9 10 11051015202530354045505560657075808590 TIME TO BOIL REFUEL POOL TO TOP OF FUEL (days)SHUTDOWN TIME (days) Time to Core Uncovery Calculations(Sheet 1 of 1)AOP 2572Revision 009-03Page 65 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEWPLANT CONDITIONTIME TO CORE UNCOVERY CALCULATIONReduced InventoryRCS FilledRefueling with Refuel Pool FullTime to Core
Uncovery==+Time to Core UncoveryTime to BoilRefuel Pool to Top of Fuel(Attachment 4)(Conservative time for worst case conditions)RCS Time to Boil (Equipment Status Board)RCS Time to Boil (Equipment Status Board) A" CS Pump to SDC(Sheet 1 of 1)AOP 2572Revision 009-03Page 66 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEWEstablish the following conditions:1.All HPSI pump handswitches in Pull-to-Lock.2.RBCCW System is operating and supplying CS pump seal coolers3.Facility 1 RWST Header is filled and vented4.2-CS-1A, A" CS Pump Suction, OPEN5.2-CS-7A, A" CS Pump Minimum Flow Recirc, CLOSED6.A" Containment Sump Outlet Header Isolation, CLOSED7.A" RWST Outlet Header Isolation, CLOSED8.A" Containment Spray Pump Discharge, OPEN9.2-SI-441, A" LPSI Pump Suction from SDC, OPEN10.11.A" SDC Heat Exchanger, OPEN12.WST, CLOSED13.2-SI-444 A" LPSI pump suction from RWST, OPEN 2 S Pump to SDC(Sheet 1 of 1)AOP 2572Revision 009-03Page 67 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEWEstablish the following conditions:1.All HPSI pump handswitches in Pull to Lock.2.Charging Pumps are aligned to a BAST tank or handswitches in PTL.3.RBCCW System is operating and supplying CS pump seal coolers4.Facility 2 RWST header is filled and vented5.6.7.8.WST Outlet Header Isolation, CLOSED9.10.11.A" SDC Heat Exchanger, CLOSED12.13.2-SI-444, A" LPSI pump suction from RWST, CLOSED14.2-SI-432, B LPSI pump suction from RWST, OPEN 2 Realigning LPSI to Supply SDC and/or SFPC(Sheet 1 of 3)AOP 2572Revision 009-03Page 68 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW1.Slowly OPEN the applicable LPSI pump discharge valve:2-SI-447, A" LPSI PUMP DISCHARGE STOP2.MONITOR CS pump discharge pressure and amps.3.IF at any time, oscillations are observed on the running CS pump discharge pressureor amps, PERFORM the following:a.STOP the running CS Pump (C-01).b.AA" Containment Spray Pump casing vent.c.vent.d.START affected CS pump.e.DETERMINE cause of oscillations.4.STOP Running CS pump.5.IF SDC Heat Exchanger.6.IFAA" SDC Heat Exchanger.7.IF all SDC flow is returning to only the RCS/Refuel Pool, PERFORM the following:a.CLOSE all LPSI injection valves (C-01):VS" LOOP 1AVS" LOOP 1B VS" LOOP 2AVS" LOOP 2B 2 Realigning LPSI to Supply SDC and/or SFPC(Sheet 2 of 3)AOP 2572Revision 009-03Page 69 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEWb.THROTTLE open one of the following LPSI injection valves until dual indication is observed (C-01):VS" LOOP 1AVS" LOOP 1BVS" LOOP 2AVS" LOOP 2B8.I F SDC flow is returning to both the Spent Fuel Pool and RCS/Refuel Pool,PERFORM the following:a.RECORD position of RRW-15 percent open: __________b.THROTTLE RW-15 to approximately 10% open.c.CRACK open ONE LPSI Injection Valve:VS" LOOP 1AVS" LOOP 1BVS" LOOP 2AVS" LOOP 2B9.START applicable LPSI Pump (C-01).10.IF SDC was supplying flow to only the RCS/Refuel Pool, PERFORM the following:a.IF in reduced inventory, THROTTLE open LPSI injection valves to raise SDC total flow to between 1400 and 1600 gpm.b.IF not in reduced inventory, THROTTLE open LPSI injection valves to raise SDC total flow to between 3500 and 4000 gpm.
2 Realigning LPSI to Supply SDC and/or SFPC(Sheet 3 of 3)AOP 2572Revision 009-03Page 70 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW11.IF SDC was supplying both the SFP and RCS/Refuel Pool, THROTTLE the following valves to obtain previous flow splits:VS" LOOP 1AVS" LOOP 1BVS" LOOP 2AVS" LOOP 2B2-R12.CLOSE the applicable CS pump discharge valve:A' CS PUMP DISCHARGE"13.ESTABLISH the following conditions:WST, CLOSED2-SI-444, A" LPSI Pump Suction from RWST, CLOSEDA" RWST Outlet Header Isolation Valve, OPENWST Outlet Header Isolation Valve, OPEN2-CS-7A, A" CS Pump Minimum Flow Recirc, OPENow Recirc, OPEN14.ALIGN HPSI Pump handswitches as directed by SM/US.15.IF desired, ALIGN charging pump suction to RWST.16.Go ToATE SDC cooling system as directed by US/SM.17.Go Touel Pool Cooling and Purification System," and OPERATE SFPC as directed by the US/SM.
2 Placekeeper(Sheet 1 of 7)AOP 2572Revision 009-03Page 71 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEWSTEPINSTRUCTIONSPAGESTARTDONE 3.0Initial Actions for Loss of SDC 53.1If fuel moving fuel notify RE to stop53.3Containment evacuation and airlock closure.53.4Determining time to boil.53.5Establishing Containment Closure.53.6HP notification.63.7Ensuring all available CAR coolers are in service.63.8Monitoring RCS level and temperature.63.9MPARs," review.63.10AC power not available, consider section 9.073.11Branching to appropriate section.74.0SDC Lost Due to Loss of Suction Pressure 84.1Determining RCS level.84.294.3Ensuring suction path to charging pumps.94.494.5Starting one charging pump.94.6Starting additional charging pump.102 Placekeeper(Sheet 2 of 7)AOP 2572Revision 009-03Page 72 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEWSTEPINSTRUCTIONSPAGESTARTDONE4.7Starting HPSI pump.104.8Performing gravity feed if desired.124.9Evacuating SDC suction piping.134.10Dispatching operator to affected LPSI pump.134.11Closing all LPSI Injection Valves.134.12Aligning flow control valves.134.13Branching to start of unaffected LPSI pump.134.14Establishing communications.144.15VA" LPSI pump.144.16V144.17Establishing SDC flow.154.18Locating and isolating leak.184.19Stopping RCS fill.194.20Monitoring listed parameters.20*4.21Actions for loss of suction pressure.204.22Stopping Containment Closure activities.204.23Branching to Section 10.0.202 Placekeeper(Sheet 3 of 7)AOP 2572Revision 009-03Page 73 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEWSTEPINSTRUCTIONSPAGESTARTDONE 5.0SDC Lost Due to Automatic Tripping of Running LPSIPump 215.1Aligning flow control valves.215.2Closing all LPSI Injection Valves.215.3Opening one LPSI Injection Valve.225.4Actions if SDC supplying both SFP and RCS/Refuel Pool225.5Starting standby LPSI pump.235.6A" CS Pump for SDC , if desired245.7245.8Actions if no LPSI or CS pumps available.255.9Actions if SDC supplying only RCS/Refuel Pool.265.10Actions if SDC supplying both SFP and RCS/Refuel Pool275.11Establishing cooldown.295.12Adjusting controller295.13Establishing additional flow through SDC HXs.295.14Checking pressure at 2-RW-66 less than 30 psig5.15Maintaining cooldown rate.305.16Limiting RBCCW flows.302 Placekeeper(Sheet 4 of 7)AOP 2572Revision 009-03Page 74 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEWSTEPINSTRUCTIONSPAGESTARTDONE5.17Closing LPSI to SDC heat exchanger isolation valve315.18Controlling RCS temperature.315.19AA" LPSI pump315.20Stopping Containment Closure activities.315.21Branching to Section 10.0.316.0SDC Lost Due to Sustained Loss of Bus 24C (VR 326.1Aligning flow control valves.326.2Monitoring RCS level and temperature.336.3346.4Opening SI-306.356.5Actions for RCS temperature greater than 200 5F or RCSboiling.356.6Branching if bus 24C and VR-11 are energized.356.7Establishing alternate SDC temperature monitoring.356.8Aligning alternate supply to VR-11 from B32.376.9Monitoring cooldown.386.10Establishing cooldown.396.11Establishing additional flow through SDC HXs.392 2 Placekeeper(Sheet 5 of 7)AOP 2572Revision 009-03Page 75 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEWSTEPINSTRUCTIONSPAGESTARTDONE6.12Maintaining cooldown.396.13Limiting RBCCW flow.396.14Controlling RCS temperature.396.15Providing additional SDC heat removal.406.16Stopping Containment Closure activities.406.17Branching to Section 10.0.407.0SDC Lost Due to Sustained Loss of Bus 24D (VR 417.1Aligning flow control valves.417.2Monitoring RCS level and temperature.417.3A" LPSI pump.427.4Opening SI-306.437.5Monitoring cooldown.437.6Establishing cooldown.437.7Establishing additional flow through SDC HXs.437.8Maintaining cooldown.447.9Limiting RBCCW flow.447.10Controlling RCS temperature.44 Placekeeper(Sheet 6 of 7)AOP 2572Revision 009-03Page 76 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEW 1STEPINSTRUCTIONSPAGESTARTDONE7.11Providing additional SDC heat removal.447.12Stopping Containment Closure activities.447.13Branching to Section 10.0.448.0Loss of P 458.1Obtaining a reference position for SDC flow control valves.458.2Adjusting controller output for failed valves458.3A468.4Determining if loss of power or air affected otherRBCCW loads.488.5Diverting flow to SDC heat exchangers.488.6488.7Establishing communications.488.8A498.9528.10Recovery from manual operations.529.0RWST Gravity Feed Makeup to the RCS and SG HeatRemoval 539.1Determining whether gravity feed is desired.539.2Ensuring adequate RWST inventory.53 Placekeeper(Sheet 7 of 7)AOP 2572Revision 009-03Page 77 of 77 Millstone Unit 2 Loss of Shutdown Cooling Level of Use C ontinuousSTOPTHINKACTREVIEWSTEPINSTRUCTIONSPAGESTARTDONE9.3A" LPSI pump suction path.539.4539.5Determining whether a steam generator is available.549.6Establishing SG heat removal.5510.0Follow-up Actions for Loss of SDC 5610.1Performing SP 2602B.5610.2Determination of time to core uncovery.5610.3Maintaining cooldown rate limits.5610.4Requesting Engineering evaluation.562 DOMINION NUCLEAR CONNECTICUT MILLSTONE 2 Lesson Title: Shutdown Cooling System Revision: 4/2 ID Number:
SDC-00-C This document is the property of Dominion Nuclear Connecticut, Inc. which controls its distribution. Further transfer, copying, and modi fication of this document are strictly prohibited without the written consent of Dominion Nuclear Connecticut, Inc.
Submitted by: Pete Strickland 10/31/07 Developer Date Reviewed by: Sandy Doboe 11/05/07 Technical Reviewer Date Reviewed by: N/A N/A Cognizant Plant Supervisor (Optional)
Date Approved by: Mike Cote 11/05/07 Training Supervisor Date See Page 10 of 82 for information on how P-103 and P-103-1 effect the SDC Suction Valves, SI-651 and SI-652 Lesson Title: Shutdown Cooling System Page 2 of 82 Revision: 4 ID Number: SDC-00-C RECORD OF CHANGES AI/COMMITMENT NO. DESCRIPTION OF CHANGE AFFECTED PAGES REV/CH 940174 This material has been upgraded to address program improvements based on student feedback identified in commitment 940174 and
associated documents.
97-3221 SDC System procedure revisions 98-5144 LPSI pump operation on minimum flow inconsistent with engineering recommendations NA Incorporate RO learning objectives 1999-1985 Incorp.
DCR-98055 (SI-651 App R mods), DCR 98052 (HPSI PTL HSs); increase clarity; and correct typos Substance:
10, 29, 52.
Typos: var.
1999-00003155 Revised Figures 2, 21, and 22 to reflect the differences in height between the top of the cold
leg and the top of the fuel.
Figures 2, 21, and 22 1999-5300 Incorporate Certification class feedback 10, 15, 20, 43 3/0 1998-011424 C hanged PEO objective to be consistent with RO Objective 5, 6, 8, 20, 33, 72 3/1 2001-3259 A dded new Tech Spec bases information defining components needed to constitute an
Operable SDC train in Modes 4, versus 5 and 6.
43, 44 3/2 2002-306 A dded TS basis info re: restrictions on using alternate suction flow path from SFP.
42 3/3 2002-632 A dded TS change regarding Mode 5 Operability revisions for 1 & 2 SDC trains.
44 3/4 2004-128 DAP
09/30/2004 Included info from TR4-33, Review of Loss of
SDC Events Jan, 2004 58 & 59 3/5 2007 - 031 Updated material prior to teaching NLIT All 4 2004-589 A dded OE for RHR gas Binding event-CR 06166 61 4/1 2007-0739 U pdated 2-SI-306 information to reflect design change DM2-00-0166-07.
18 4/2 Lesson Title: Shutdown Cooling System Page 3 of 82 Revision: 4 ID Number: SDC-00-C TABLE OF CONTENTS C. PURPOSE........................................................................................................................
..5 2. System Purpose.................................................................................................................
5 D. SYSTEM DESCRIPTION...................................................................................................
5 2. System Overview...............................................................................................................
5 3. System Flow Paths.............................................................................................................
5 4. System Interfaces..............................................................................................................
.7 E. MAJOR COMPONENTS....................................................................................................
9 2. SDC (LPSI) Suction Isolation Valves (2-SI-652, 651)
.........................................................
9 3. Shutdown Cooling (LPSI) Pumps.....................................................................................
11 4. LPSI Mini Recirc Valves (2-SI-659, 660)
...........................................................................
12 5. Shutdown Cooling HXs (X-23A, B)....................................................................................
14 6. SDC Heat Exchanger Flow Control Valve (2-SI-657)
.........................................................
15 7. SDC Total Flow Control Valve (2-SI-306)
...........................................................................
17 8. LPSI Injection Throttle Valves..........................................................................................
19 9. LPSI/SDC Relief Valves (2-SI-469, 468, 439)
....................................................................
20 10. SDC High Point Evacuation Subsystem.........................................................................
21 11. Reactor Coolant System Level Indication.....................................................................
22 F. OPERATION......................................................................................................................
..24 2. Normal Operation (Shutdown Cooling in Service)............................................................
24 3. Abnormal Operation.........................................................................................................
38 4. Maintenance and Testing.................................................................................................
41 5. Administrative Requirements...........................................................................................
42 G. MALFUNCTIONS AND FAILURES..................................................................................
44 2. Core Boiling with RCS Vent Path or Nozzle Dams Installed.............................................
44 3. Failures leading to a Loss of Shutdown Cooling..............................................................
44 H. OPERATING EXPERIENCES..........................................................................................
48 2. Introduction...................................................................................................................
....48 3. Loss of Coolant Inventory.................................................................................................
49 4. Loss of Decay Heat Removal Capability
............................................................................
50 5. Cold Over Pressure Events..............................................................................................
52 6. Conditions Affecting the Severity of a Shutdown Cooling Incident...................................
53 7. Conclusion.....................................................................................................................
...55 8. SER 12-86 High Cooldown Rate Due To Inaccurate Closed Position Indication On Motor-Operated Valves................................................................................................................
......56 9. SER 19-91 Loss Of Decay Heat Removal Capability Due To Inappropriate Maintenance And Testing....................................................................................................................
.........56 10. Review of Loss of Shutdown Coolant Events 01/2004.................................................
57 Lesson Title: Shutdown Cooling System Page 4 of 82 Revision: 4 ID Number: SDC-00-C I. TABLES.........................................................................................................................
......59 2. Component Design Data Table........................................................................................
59 3. Power Supply Summary Table.........................................................................................
62 4. Alarm Summary Table......................................................................................................
63 5. Instrument Summary Table..............................................................................................
65 J. REFERENCES....................................................................................................................
67 K. FIGURES........................................................................................................................
.69 L. ATTACHMENTS..................................................................................................................
70 Lesson Title: Shutdown Cooling System Page 5 of 82 Revision: 4 ID Number: SDC-00-C C. PURPOSE
- 2. System Purpose The Shutdown Cooling System (SDC) cools the reactor when Reactor Coolant System (RCS) temperature is too low to effectively transfer
decay heat via the steam generators. It also functions to maintain a
suitable temperature for refueling and maintenance activities. Portions
of the Low Pressure Safety Injection (LPSI) and Containment Spray (CS) systems are used as the Shutdown Cooling (SDC) System.
PEO-1 D. SYSTEM DESCRIPTION
- 2. System Overview During non-accident conditions, when allowed by Technical Specifications (<1750 psia), portions of the ESF systems are aligned to
function as SDC components. When the Reactor Coolant System (RCS)
is less than 300° F and less than 265 psia, sections of the Low Pressure Safety Injection System and the Containment Spray System are aligned
as the Shutdown Cooling (SDC) Syst em. The Shutdown Cooling System uses the LPSI pumps to circulate reactor coolant through the shutdown cooling heat exchangers.
The Low Pressure Safety Injection System can also be used to transfer water, in either direction, between the Refueling Water Storage Tank (RWST) and the refueling cavity. Interconnections with the Chemical
Volume Control System (CVCS) and with the Spent Fuel Pool Cooling and
Purification systems are also provided.
- 3. System Flow Paths The Shutdown Cooling System takes suction through a common header
that originates at the Loop 2 RCS hot leg and then splits to provide a flow
path to both of the Low Pressure Safety Injection (LPSI) pumps. The LPSI
pumps discharge to a common header that contains a total flow control
valve (2-SI-306) and two SDC heat exchangers. The discharge flow from
the SDC heat exchangers and the flow from the total flow control valve
combine. The combined SDC system flow enters the four RCS cold legs through the safety injection nozzles.
PEO-2A, RO-1A Figure 1 Figure 2 The Shutdown Cooling System contains borated water which is a weak acid, so all system piping is constructed of stainless steel. The common
12 inch diameter suction line connects to the bottom of Loop 2 RCS hot
leg. The suction line is equipped with two motor operated suction isolation
valves (2-SI-652 & 2-SI-651). The common suction line is routed inside
Containment to the piping penetration area. The pipe run rises to about
10 inches above the centerline of the Loop 2 hot. This elevation difference creates a high point loop downstream of the motor operated isolation valves but inside Containment. This loop seal can Figure 3
Figure 4 Lesson Title: Shutdown Cooling System Page 6 of 82 Revision: 4 ID Number: SDC-00-C collect entrained air that could threaten the prime on a LPSI pump operating in the SDC mode. Air entrainment can occur during conditions
when level is lowered in the RCS, so a High Point Vent And Vacuum
Priming Subsystem has been installed to take a suction at this high point
After passing through the containment wall, the Shutdown Cooling Suction
pipe continues for about 10 feet to a manual isolation valve (2-SI-709).
After the manual isolation valve, the pipe expands to 14 inches in diameter
and runs down to the ESF rooms on the -45 foot level of the Auxiliary
Building where it then divides to supply both LPSI pumps. The LPSI
pumps are located on the -45 foot elevation of the Auxiliary Building.
Figure 5 The discharge piping for each Shutdown Cooling (LPSI) Pump is 10 inch stainless steel pipe that increases to 12 inch diameter pipe at the point
where the LPSI pump discharge lines combine to form the common
header containing the SDC Total Flow Control Valve (2-SI-306). The 'A' &
'B' LPSI pumps are also connected to the SDC heat exchangers. The
LPSI pumps are connected to the SDC heat exchangers via 10 inch piping
unique to the SDC system. The heat exchangers, which are aligned to the Containment Spray pumps during power operation, are aligned for RCS heat removal while shutdown. Reactor coolant flow is manually aligned to
the tube side of either or both heat exchangers. On initial startup both
heat exchangers are placed in service and depending on decay heat load, the second heat exchanger may be removed from service. The outlets of
the SDC heat exchangers are connected to the common LPSI header
downstream of the SDC Total Flow Control Valve (2-SI-306) via 12 inch
piping which is also unique to the SDC system. The SDC Total Flow
Control Valve is operated in the remote manual mode during Shutdown
Cooling operation. The valve is maintained fully open once cooling is
initiated.
Figure 5 PEO-2B, RO-1B SDC flow (and therefore heat transfer) through the SDC heat exchangers is manually controlled utilizing an air operated SDC HX Flow Control Valve
(2-SI-657) which is located in the common heat exchanger outlet piping
and is positioned from C0-1. The discharge flow from the SDC heat
exchangers and the discharge flow from the total flow control valve (2-SI-
306) combine, and the total SDC system flow enters the four RCS cold
legs through the Safety Injection nozzles. The nozzles penetrate the top of the cold legs and have thermal sleeves that minimize thermal stress imposed on the RCS piping due to the introduction of cold water. The
benefits of thermal sleeves are most significant during safety injection
when the differential temperature between the metal and the fluid is the
greatest.
Lesson Title: Shutdown Cooling System Page 7 of 82 Revision: 4 ID Number: SDC-00-C The total Shutdown Cooling System flow to the four reactor coolant system cold leg injection points is regulated by throttling the motor
operated LPSI loop injection valves during SDC operations. The SIAS
open signal to the LPSI injection valves is defeated during Reduced
Inventory operations to prevent excessive system flow.
The Shutdown Cooling System is designed to withstand a static
pressure of 300 psig plus an additional 200 PSID of head added by an
operating LPSI pump. The pump suction and the pump discharge
piping are protected by relief valves. Additional over pressure protection
is provided by an interlock which prevents the SDC Suction Isolation
valves (2-SI-652 & 2-SI-651) from being opened when wide range
Pressurizer pressure exceeds 265 psia. The 300 psig static suction pressure that the Shutdown Cooling System is designed to withstand is the sum of 265 psia Pressurizer pressure plus an additional 35 psia of static pressure due to elevation head.
- 4. System Interfaces
The Shutdown Cooling System has only a limited amount of piping and valves used exclusively for SDC system operation. The
Shutdown Cooling System makes extensive use of the components and piping of other systems to perform its cooling function.
The SDC HXs are shared between the Containment Spray system and
the Shutdown Cooling system. LPSI pumps provide the flow of
coolant through the SDC heat exchangers. The LPSI and CS systems are ECC systems. The Containment Spray pumps are racked down during SDC operation.
PEO-3A Figure 6 e. Reactor Coolant System (RCS)
During Shutdown Cooling operations the LPSI pumps take a suction from the RCS through a nozzle on the bottom of the RCS Loop 2 hot
leg pipe.
PEO-3B Figure 4 Return SDC flow is through the safety injection nozzle on each of the four reactor coolant system cold leg pipes. This provides four
separate flow paths from the SDC system to the reactor core.
Figure 1 f. Reactor Building Closed Cooling Water System (RBCCW)
The Shutdown Cooling system heat exchangers are cooled by RBCCW which flows through the shell side of the heat exchangers.
RBCCW also cools the LPSI pump seals.
PEO-3C Lesson Title: Shutdown Cooling System Page 8 of 82 Revision: 4 ID Number: SDC-00-C g. Chemical and Volume Control System (CVCS)
Connections to and from the Chemical and Volume Control System are provided to permit excess letdown and additional purification.
PEO-3D When RCS pressure is less than 265 psia, insufficient differential
pressure exists to achieve the maximum letdown flow rate of 128 gpm
using the normal CVCS flow path. Under this condition, the
interconnection between SDC and the letdown heat exchanger (via
SI-040) is used to provide additional, or "excess," letdown capability.
While on SDC, purification of the RCS coolant and refueling pool
water may be accomplished utilizing the ion exchangers in the CVCS system. This process is referred to as "Additional Purification."
Figure 7 Figure 8 The cross-connect between the Shutdown Cooling System and the Chemical & Volume Control System (CVCS) allows RCS coolant from
the outlet of the SDC heat exchanger to enter the inlet of the letdown
heat exchanger (via 2-SI-040). The coolant is then returned to the
Shutdown Cooling System at the LPSI pump suction via 2-CH-024.
- h. Spent Fuel Pool Cooling System (SFPC)
The Shutdown Cooling System can be used to supplement or replace
the Spent Fuel Pool Cooling (SFPC) System during periods of high
heat load in the Spent Fuel Pool. There is a connection on the LPSI
pump suction cross-connect line from the Spent Fuel Pool Cooling
system (2-SI-442). The SFPC water is cooled in the SDC heat
exchanger and returned to the SFPC system through a return line (2-
SI-458) on the outlet of the SDC heat exchangers.
PEO-3E Figure 9 PEO-2C, RO-1C i. Safety Injection Tanks (SITs)
The existing Engineered Safety Features (ESF) piping can be used to fill or drain the Safety Injection Tanks using the LPSI pumps.
Figure 10 All SIT isolation valves are maintained closed during normal
Shutdown Cooling operation.
- j. Refueling Water Storage Tank (RWST)
The existing Engineered Safety Features (ESF) piping can be used
to transfer water, in either direction, between the RWST and the
refueling cavity.
Figure 1 Lesson Title: Shutdown Cooling System Page 9 of 82 Revision: 4 ID Number: SDC-00-C k. Radwaste and ESF Room Ventilation The ESF rooms are normally cooled by the Radwaste Ventilation system. To ensure that ambient conditions will allow continuous operation of the LPSI pump motors, room cooling is provi ded by ESF Room Ventilation during SDC operation.
The A and B pump rooms each contain an ESF fan and cooler that provide a closed
cycle recirculation of the air within the room. The coolers reject
heat to the Reactor Building Closed Cooling Water (RBCCW)
System. l. In-house Electrical The LPSI pumps and LPSI system motor operated valves are powered from emergency buses 24C and 24D.
The emergency buses can be powered from the emergency diesel generators on a
loss of normal power to the buses and either emergency bus can be
powered from Unit 3 through 34A or B.
contaminated leak off from the LPSI pump seal packages, drain lines
from valves and equipment leak o ff, LPSI pump drains, and system relief valve discharges for future disposal.
- n. Instrument Air Instrument air is used as the motive force for two SDC valves, the
SDC Total Flow Control Valve (2-SI-306) and the SDC heat
exchanger Flow Control Valve (2-SI-657). Instrument air, along with
backup air bottles, also supplies operating air to the Safety Injection
Mini Flow Valves (2-SI-659, 660).
E. MAJOR COMPONENTS
- d. Purpose The SDC Suction Isolation Valves provide for separation of the
RCS Loop 2 Hot Leg and the LPSI pump suction during normal
power operation.
PEO-4A e. Design and Operating Characteristics The Low Pressure Safety Injection System (Shutdown Cooling
suction line) is isolated from the Reactor Coolant System by two, 12-inch, motor operated gate valves (2-SI-652 and 2-SI-651) in series
with each other. Both valves are located inside Containment. The
valves will fail as is on a loss of power.
PEO-4A Figure 1 Lesson Title: Shutdown Cooling System Page 10 of 82 Revision: 4 ID Number: SDC-00-C Outside containment, there is a 12 inch manual isolation gate valve (2-SI-709) in the LPSI pump suction line. This SDC Suction Header
Isolation valve provides for Containment isolation during power
operations.
- f. Control and Instruments The Suction Line Isolation Valve motor operators are powered from
MCC B61 (SI-652) and MCC B51 (SI-651).
The 480V power supply to 2-SI-652 is normally isolated in order to prevent inadvertent opening and subsequent system over
pressurization during power operation. This isolation switch is located
in the Control Room behind panel C80. Operation of this switch will
actuate annunciator D-39 on C-01 whenever power is made available to 2-SI-652.
To address single-failure concerns for post-accident boron precipitation, 2-SI-651 is equipped with an alternate power supply from 480 volt MCC B61. An administratively controlled kirk-key
shifts control to local panel and bypasses the RCS pressure
interlock (280 psia).
PEO-4B The control switches for SI-651 and SI-652 are located in the Control Room on panel C-01. They are two position OPEN/CLOSE keylock
switches. Each of the valves has RED (open) and GREEN (closed)
indication lights.
RO-2A Procedurally, the LPSI system, SDC heat exchangers, and
interconnecting piping can not be exposed to an RCS pressure greater than 265 psia or temperature greater than 300° F. To protect the piping against excessive pressure SI-651 and SI-652 are interlocked with the low range Pressurizer pressure channels (P-103 and P-103-1). The range of these instruments is 0 to 1600 psia.
Pressure is displayed on C-03 and on C-21 and can also be monitored on the Plant Process Computer. The SDC Suction Isolation Valves are interlocked closed if RCS pressure is greater than 280 psia. If SI-651 or SI-652 were already open (i.e. SDC in
service) and pressure rose above 280 psia an alarm is received on
C01 alerting the operators.
Each Suction Isolation Valve motor operator has a manual
handwheel and clutch mechanism allowing local operation of the
valve.
Lesson Title: Shutdown Cooling System Page 11 of 82 Revision: 4 ID Number: SDC-00-C 3. Shutdown Cooling (LPSI) Pumps
- d. Purpose When used for Shutdown Cooling operation, the purpose of the LPSI Pumps is to provide shutdown cooling flow through the
reactor core and shutdown cooling heat exchangers.
PEO-4C e. Design and Operating Characteristics The LPSI pumps are single stage centrifugal pumps capable of
delivering 4500 gpm each at run-out conditions. The pumps are
designed to withstand the sum of their suction pressure (300 psig
maximum) and the maximum expected discharge head which totals
approximately 500 psig. Under no circumstance should the pump
discharge pressure (e.g., system pressure) be allowed to exceed 500
psig. PEO-4C Figure 1 Each pump is equipped with a mechanical shaft seal to minimize leakage of potentially contaminated fluid from the system to the ESF
rooms. Seal leakage is contained and directed to the Equipment
Drain Sump Tank. The seal package temperature is maintained
within limits by water from the pump discharge that has been cooled
by RBCCW in its respective seal cooler. The RBCCW flow to the seal
coolers is facility specific. The seal package is designed to operate, without the aid of seal cooling, at temperatures as high as 350° F, but cooling is provided to extend the expected operating lifetime for the
seal package.
The LPSI pumps must pump a minimum of 100 gpm each to carry away heat produced by mechanical friction within the pump itself.
This minimum flow prevents pump overheating and resultant damage
to the pump and pump seal package. To provide this minimum flow, each pump has an orificed minimum flow recirculation line. The recirc
line routes a portion of the pump discharge flow back to the Refueling
Water Storage Tank (RWST) through a line common to the LPSI, HPSI, and CS Pumps.
Plant data shows actual minimum flow is approximately 115 gpm.
Pump discharge pressure while operating on minimum flow is
approximately 220 psig. During inservice testing with a flowrate of
approximately 3,100 gpm discharge is approximately 175 psig.
- f. Control and Instruments The driving force for the pumps is provided by 400 HP electric
motors powered from 4.16 KV emergency buses 24C and 24D for
LPSI pumps A and B respectively. The motors are air cooled.
PEO-5 A motor breaker trip will occur as the result of an over-current
condition (in excess of 100 amps), or a ground fault. A trip will also
Lesson Title: Shutdown Cooling System Page 12 of 82 Revision: 4 ID Number: SDC-00-C occur if the motor is running for a non-SIAS condition and a Loss of Normal Power (LNP) occurs. This "Load-shed" trip, generated from
the "Main Generator Final Coastdown Circuit," locks out the LPSI
pump breaker in preparation for energizing the 24C and 24D buses
from the Emergency Diesel Generator (EDG). The LPSI pump
breaker must then be reset before the pump can be restarted by the
operator. The "Load-shed" trip, generated from the Main Generator Final Coastdown Circuit is blocked during SDC operation.
The LPSI system pumps will also trip on receipt of a Sump Recirculation Actuation Signal (SRAS). The Engineered Safeguards
Actuation System (ESAS) system generates an SRAS when the
RWST level lowers to the appropriate level. The occurrence of
inadvertent LNP and SRAS signals while on Shutdown Cooling have
caused a simultaneous loss of both LPSI pumps and a corresponding
loss of core cooling. Because of this, these signals are defeated when Shutdown Cooling is in operation.
Each LPSI pump has a START/STOP pistol switch with GREEN/YELLOW/RED indicating lights on C-01. The
GREEN/YELLOW/RED lights are off, tripped, and run indications.
Each LPSI pump also has two sets of BLUE/WHITE indicating lights on panel C01X. One set of lights is for SIAS, the other for SRAS.
The BLUE light indicates that the pump is in its 'accident required'
position and the WHITE light indicates that the pump is unable to
perform its accident required function. The white light will light when a
loss of control power to the motor's control circuit occurs.
RO-2B The discharge pressure for each LPSI pump is displayed on C-01 and
can be monitored on the Plant Process Computer. The control board meter for the "A" pump (PI-302X) and for the "B" pump (PI-302Y )
have a range of 0 to 500 psig.
Figure 11 4. LPSI Mini Recirc Valves (2-SI-659, 660)
pumps (and other ECCS pumps) from dead headed operation. They
provide a flowpath through the pump to remove the heat produced
from mechanical friction of pump operation.
PEO-4D Lesson Title: Shutdown Cooling System Page 13 of 82 Revision: 4 ID Number: SDC-00-C e. Design and Operating Characteristics The two valves (2-SI-659, 660) are 4 inch air operated globe valves that fail open on a loss of air. The valves use instrument air as the
motive force and each have two accumulators installed in the air
supply lines. The accumulators provide sufficient capacity to operate
the valves for two cycles following a loss of instrument air supply. An
isolated air bottle and regulator for each valve are available as a
backup supply in the event of an accident to the instrument air system. PEO-4D Figure 1 The valves are in series in the recirculation line providing single failure protection when the valves are required to be shut. The valves are
normally maintained open.
During the "warm up" phase of SDC preparation the valves are closed
to allow system temperature and pressure to rise.
During accident conditions the valves are closed during sump recirc
to prevent an unmonitored release through the RWST vent to
atmosphere.
When warmup is complete, just prior to initiating Shutdown Cooling, the LPSI pump manual recirc isolation valves (2-SI 449/450) are
closed, and 2-SI-659 and 2-SI-660 are re-opened to provide
minimum flow protection for the HPSI pumps.
- f. Control and Instruments The recirc valves are normally disabled in the OPEN position by a
key switch (OPER/INOP) on C-01 to provide for pump recirculation
flow during normal plant operation and surveillance. Each valve
has a key switch and a handswitch (CLOSE/N/OPEN) for individual
operation. With the key switches in the OPER position the valves
will automatically close on a Sump Recirculation Actuation Signal (SRAS) or can be manually closed by the operator. In the INOP position the valves cannot be closed either manually or automatically.
RO-2C The recirc valves CLOSE/N/OPEN handswitch is on C-01 in the main control room and has GREEN/RED indicating lights.
There are also BLUE/WHITE indicating lights on C-01X in the main
control room. The BLUE light indicates that the valve is in its 'accident
required' position for SRAS and the WHITE light indicates that the
valve is unable to perform its accident required function.
Lesson Title: Shutdown Cooling System Page 14 of 82 Revision: 4 ID Number: SDC-00-C 5. Shutdown Cooling HXs (X-23A, B)
- d. Purpose The Shutdown Cooling Heat Exchangers (SDC HXs) transfer heat from the RCS to the RBCCW system during plant cooldown and cold
shutdown conditions (i.e., SDC, SFPC operations).
PEO-4E e. Design and Operating Characteristics The SDC HXs (X-23A/B) are U-tube, shell and tube type heat
exchangers. There is single pass RBCCW flow on the shell side of the HX. The shell side of the HX is constructed of carbon steel with
the wetted surfaces clad with stainless steel. The maximum design
pressure and temperature on the shell side are 150 psig and 250° F.
The two pass borated water flow is through the U-tubes that are made
of Austenitic stainless steel. The maximum design pressure and temperature on the tube side are 500 psig and 400° F.
PEO-4E Figure 1 During power operation, the heat exchangers are aligned to the Containment Spray system. During SDC operations the outlet of the
heat exchangers are cross connected to the LPSI System for SDC
cooling and related operations.
The two Shutdown Cooling heat exchangers are located in the "A" and "B" Engineered Safety Features (ESF) rooms on the -45 foot
elevation in the Auxiliary Building.
Shutdown Cooling System flow through the tube side of the heat exchanger must be maintained at
less than 4800 gpm in order to prevent damage to the tubes. Reactor
Building Component Cooling Water (RBCCW) from the respective
facility is provided to the shell side of the heat exchanger at a rate of up to 4800 gpm. Flow on the shell side is controlled by throttling the RBCCW outlet manual isolation valves (2-RB-14A/B).
The two heat exchangers are sized to cool the RCS from approximately 300° F to 130° F (and maintain this temperature) 27.5
hours after shutdown.
- f. Control and Instruments There are local temperature indicators associated with the shell and tube flows through the heat exchangers. There is a SDC HX OUT
TEMP indicator for each heat exchanger on C-01. It has a range of 0°
F to 400° F. Additionally, indication of the fluid temperature at the
inlet to the Shutdown Cooling heat exchangers is displayed locally on
TI-3025 and TI-3026. Heat exchanger temperatures are also
available on the Plant Process Computer.
Figure 11 Lesson Title: Shutdown Cooling System Page 15 of 82 Revision: 4 ID Number: SDC-00-C 6. SDC Heat Exchanger Flow Control Valve (2-SI-657)
- d. Purpose The SDC Heat Exchanger (HX) Flow Control Valve controls the rate of flow through the SDC HX thereby controlling the heat
removal rate from the reactor core.
PEO-4F e. Design and Operating Characteristics The SDC Heat Exchanger Flow Control Valve (2-SI-657) is a 10 inch
air operated ball valve that fails closed on a loss of instrument air or
control power. The operating solenoid for SI-657 receives power from
125 VDC DV10 and the HIC receives power from 120 VAC VA10.
PEO-4F During SDC operation, flow through the SDC heat exchangers (and
therefore heat transfer) is manually controlled by positioning flow
control valve (2-SI-657) from HIC-3657 on C0-1. The optimum output range of HIC-3657 is between 35% and 60%. This r ange was chosen to provide adequate valve motion when responding to SDC
temperature perturbations, while yielding a controllable flow
change for a small change in controller output. However, controlling outside of this band is acceptable based on what is considered necessary to adequately stabilize SDC and RCS
temperatures. Maintaining "SDC FLOW CNTL, FIC-306" in manual
and full open also reduces the sensitivity of SDC to RCS, T351Y, to 2-SI-657 position changes.
When SDC is not in service, the HX flow control valve is disabled in the closed position to ensure system and facility separation during
normal plant operation. This is accomplished by:
PEO-6 Key locked closed on C-01.
Manual handwheel disengaged (stem backed out of actuator, locking hex nut tightened) and handwheel locked.
A manual handwheel was installed on the HX flow control valve
because the valve fails closed in the event that a loss of either
Instrument Air (IA) or control power resulting in a loss of shutdown
cooling. Credit is taken for the handwheel in order to comply with
10CFR50 Appendix R for cold reactor shutdown following a fire.
The HX flow control valve is equipped with a lantern ring between two
sets of stem packing. Leakage collected in the lantern ring is piped to
the Auxiliary Building Drains system.
Lesson Title: Shutdown Cooling System Page 16 of 82 Revision: 4 ID Number: SDC-00-C f. Control and Instruments The SDC HX Flow Control valve has a two position keylock (LOCKED CLOSED/MANUAL) switch on C-01 with GREEN/RED indicating
lights. The key can only be inserted and removed when the switch is
in the LOCKED CLOSED position. The valve can be aligned for
remote positioning to support Shutdown Cooling System operation by
taking the keylock switch to MANUAL position. In the MANUAL
position the solenoid valve (HY657) is energized admitting air to the valve positioner. The valve can then be positioned from the Control Room utilizing HIC-3657 located on C-01. In this alignment the
controller allows the Control Room Operator to manually adjust the
Shutdown Cooling System flow rate through the Shutdown Cooling
heat exchanger(s), and thereby regulate the temperature of fluid
being returned to the Reactor Coolant System (RCS).
RO-2D PEO-6
HIC-3657 has a potentiometer and a 0 to 100% scale on its faceplate. When required to operate the SDC HX Flow Control Valve, the key is
inserted in the keylock switch and placed in MANUAL. The
potentiometer is adjusted to open/close SI-657. When full open the
meter will indicate 100% and 0% when full close.
RO-3A The outlet flow from the Shutdown Cooling heat exchangers is
monitored by FE-3023 and FE-3024 for heat exchanger "A" and "B",
respectively. The control board meters have a range of 0 to 5000
gpm. Flow is also indicated on the plant process computer.
Figure 11 The Shutdown Cooling heat exchanger flow control valve (2-SI-657) is normally positioned from the Control Room utilizing HIC-3657 on
C-01. The valve can also be operated locally using a manual
handwheel. The manual operator is normally locked in the full open
position whenever the valve is being operated in the air operator
mode. In order to use the handwheel a hex nut on top of the actuator
needs to be loosened allowing the handwheel to move downward on top of the actuator diaphragm.
The manual actuator for 2-SI-657 is reverse acting, i.e., clockwise rotation of the local manual handwheel opens the valve by pushing
down on the actuator and the valve stem. The downward motion
opens the valve. Care must be taken when operating the valve
manually to avoid over-torqui ng and damaging valve components.
There are two temperature indications available to monitor the SDC
performance. These are displayed on a strip chart recorder on C-01
and monitored by the Plant Process Computer. Each has a range of 0
to 400° F. The temperature of the Shutdown Cooling suction line from
the Reactor Coolant System (RCS) is monitored by TE-351X and displayed on recorder TR-351 along with the temperature from the LPSI pump discharge common header, downstream of the SDC Figure 11
Lesson Title: Shutdown Cooling System Page 17 of 82 Revision: 4 ID Number: SDC-00-C Total Flow Control Valve, 2-SI-306 (TE-351Y). The discharge fluid being monitored is the combination of the flow from the heat
exchanger(s) and the flow through the total flow control valve. 7. SDC Total Flow Control Valve (2-SI-306)
- d. Purpose The SDC Total Flow Control Valve is normally full open during SDC operations. A mechanical valve stop limits the flowrate in the LPSI system during SIAS operation preventing LPSI pump runout.
PEO-4G During SDC operations SI-306 and SI-657 are adjusted as
necessary to control the rate of temperature change.
- e. Design and Operating Characteristics The SDC Total Flow Control Valve (2-SI-306) is a 12 inch air
operated ball valve that fails open on a loss of instrument air or
control power. The operating solenoid for SI-306 receives power from
125 VDC DV10 and the FIC receives power from 120 VAC VA10.
PEO-4G Figure 1 The discharge of both LPSI pumps passes through the total flow control valve during SDC operation (and SIAS injection). The valve
has a mechanical stop that limits how far the valve will open (approximately 50 % open). The purpose of this stop is to limit the
flowrate and aid in preventing runout of the LPSI pumps.
The SDC Total Flow Control Valve is equipped with a pneumatic
actuator and a manual actuator that are connected to opposite sides
of the valve plug shaft. The air actuator is a spring-to-open diaphragm
type actuator.
The SDC Total Flow Control Valve is aligned to support Shutdown
Cooling System operation by taking the keylock switch to the SDC
position and operating the FIC in remote manual. Positioning in this
alignment is based on maintaining a set Shutdown Cooling system
flow based on LPSI pump operation (1 or 2 pumps). Valve position is set using the potentiometer on the front of the controller (FIC-306) located on C-01. A flow sensor, located downstream of the union of the total flow control valve outlet and the SDC HX flow control valve return, measures total system flow. The flow signal from the
transmitter is used as an input to the Plant Process Computer (PPC).
PEO-6 When SDC is not in service, the solenoid valve located in the pneumatic signal line to the diaphragm of the actuator for HV-306 is
electrically disabled to prevent air pressure from reaching the
diaphragm. With no air applied, spring force is sufficient to hold
thevalve in the full open position. The manual operator on the
opposite side of the shaft can be manually engaged and disengaged
from the valve plug shaft by means of a coupling pin. When engaged, this operator has sufficient mechanical advantage to over-ride PEO-6 Lesson Title: Shutdown Cooling System Page 18 of 82 Revision: 4 ID Number: SDC-00-C operation of the pneumatic actuator in all cases. This handwheel is normally locked to prevent inadvertent operation.
During power operation, when SDC is not in service, extraordinary
care is taken to make certain that the SDC total flow control valve (2-
SI-306) cannot be closed when the Emergency Core Cooling
Systems (ECCS) are required to be operable. Since it is located in
the common LPSI pump discharge header, closure of this valve
would prevent LPSI injection flow. Therefore, whenever the LPSI
system is required as part of an Operable train of Emergency Core Cooling Systems (ECCS) this valve is aligned such that it becomes a "passive" component (i.e., similar to a piece of piping) by ensuring the valve is:
PEO-6 Key locked open at C-01. This de-energizes the control circuit and vents the pneumatic operator.
Control solenoids for the pneumatic actuator are de-energized electrically by removal of the fuse block associated with the control circuit.
The Instrument Air supply to the pneumatic actuator is isolated and the actuator is vented in order to fail the valve open.
The local manual operator is engaged, pinned and opened.
The local manual operator is chained and locked open.
The SDC Total Flow Control Valve is equipped with a lantern ring
between two sets of stem packing. Leakage collected in the lantern
ring is piped to the Auxiliary Building Drains system.
During 2R18 a new valve body will be installed due to chronic valve stem leakage in the past. The new packing box will be provided with an
enhanced packing arrangement, which will consist of moving the lantern ring to the bottom of packing box and then installing a 5 ring set consisting of Duramettalic D 110, 3 graphite rings and then a
Duramettalic packing D 110. This will require removing the packing leak
off lines in this DCN package. DM2-00-0166-07.
- f. Control and Instruments The SDC Total Flow Control valve has a two position keylock (SDC/SI) switch on C-01 with GREEN/RED (close/open) indicating
lights. In the SI position the solenoid valve (HY306) is de-energized causing
the valve to fail open. The key can only be inserted and removed
when the switch is in the SI position.
Lesson Title: Shutdown Cooling System Page 19 of 82 Revision: 4 ID Number: SDC-00-C The valve is aligned to support Shutdown Cooling System operation by inserting the key and taking the keylock switch to the SDC position
and operating the FIC in remote MANUAL. Valve position is manually adjusted using the potentiometer on the front of the controller (FIC-306) located on C-01. A 0 to 100% meter is located on the face
of the controller. When the valve is full open the output is 0% and
100% when full closed.
RO-2E RO-3B A loss of either Instrument Air or control power to the valve results in the valve failing to the full open position. The majority of flow control
circuit failures will also cause the valve to fail to the open position.
The LPSI injection Valves are maintained in a throttled position during
Shutdown Cooling System operation which ensures that the LPSI
pumps will not reach run-out conditions in the event that the flow
control valve were to fail to its full open position.
The manual actuator for 2-SI-306 is reverse acting, i.e., clockwise
rotation of the local manual handwheel will open the valve. Care must
be taken when operating the valve manually to avoid over-torquing
and damaging valve components.
Total flow through the Low Pressure Safety Injection System is
monitored by FE-306 and is displayed on a control board meter (FIC-306) which has a range of 0 to 7000 gpm. Total flow indication is
also available from the Plant Process Computer.
Figure 11 8. LPSI Injection Throttle Valves
RCS cold legs.
PEO-4H e. Design and Operating Characteristics The injection valves (2-SI-615, 625, 635, 645) are 6 inch motor
operated globe valves.
These valves are powered from 480 VAC buses MCC-22-1E and MCC-22-1F (B5118, B5119, B6116, and
B6111 respectively). The four injection valves automatically open on
receipt of a Safety Injection Actuation Signal (SIAS) from the
Engineered Safeguards Actuation System (ESAS). When SDC is in
service during reduced inventory operations, the SIAS open signal to the LPSI injection valves is blocked and the valves are positioned by the control room operator.
PEO-4H The division of Shutdown Cooling flow to the four RCS cold legs is controlled by the motor operated LPSI injection valves. The valves
are maintained in a throttled position during Shutdown Cooling
System operation to limit total SDC system flow.
Lesson Title: Shutdown Cooling System Page 20 of 82 Revision: 4 ID Number: SDC-00-C f. Control and Instruments Each injection valve has a three position, CLOSE/NORM/OPEN, switch on C-01 with GREEN/RED (close/open) indicating lights.
There are BLUE/WHITE indicating lights on C-01X in the main control
room. The BLUE light indicates that the valve is in its 'accident
required' position. The WHITE light indicates that the valve is unable
to respond to an accident signal.
RO-2F Each motor operator has a manual handwheel and clutch mechanism
allowing local operation of the valve.
Each LPSI injection line to the Reactor Coolant System (RCS)
contains a flow sensor. These indications (FI-312, 322, 332, 342) are
displayed in the Control Room on C-01 utilizing a digital read-out.
They are also used as an input to the Plant Process Computer.
Figure 11 A two-inch warming line, containing a manual isolation valve (2-SI-
400), extends from the Loop 2A LPSI injection header to the SDC suction line. This warm up line taps off the Loop 2A LPSI injection
header prior to the motor operated injection valve (2-SI- 635) and
provides a closed loop flow path for SDC warm-up prior to operation of the Shutdown Cooling System. During warm-up of the
Shutdown Cooling System, the "LPSI to RCS Loop 2A" flow indicator (FI-332) can be used to monitor warm-up flow. Nominal warm-up flow is approximately 280 gpm. Minimum acceptable flow indication on
this meter during system warm-up is 100 gpm (pump minimum flow
requirement). Because the meter has a range of 0 to 2000 gpm, the
flow rate can be read more accurately at these low flow conditions on
the Plant Process Computer.
PEO-4I PEO-2D, RO-1D
Figure 12
Figure 11 9. LPSI/SDC Relief Valves (2-SI-469, 468, 439)
- d. Purpose Relief valves provide over pressu re protection to the SDC system components and piping.
- e. Design and Operating Characteristics All the relief valves for the LPSI system are the fully enclosed, pressure tight type relief valve with provisions for gagging the valves. Two relief valves are provided on the Shutdown Cooling suction line
portion of the Low Pressure Safety Injection system to provide over pressure protection. One of the reliefs (2-SI-469), located between
the two motor-operated suction isolations inside the Containment
Building relieves to the Primary Drain Tank (PDT).
Lesson Title: Shutdown Cooling System Page 21 of 82 Revision: 4 ID Number: SDC-00-C The other suction relief valve (2-SI-468) is located on suction line between the outboard containment isolation valve and the pump
suctions. This relief discharges to the Equipment Drain Sump Tank.
Both valves have a lift setting of 300 psig. These relief valves are
referred to as thermal reliefs because they are sized to protect against
normal thermal expansion that might occur when these portions of
piping are isolated and heat up. 2-SI-468 is also sized to provide
overpressure protection with all three charging pumps running on a
solid RCS. The reliefs do not have sufficient capacity to protect the
system against a pressure excurs ion resulting from exposure to normal RCS pressure (i.e. SDC suction valves opening at NOT/NOP).
The LPSI discharge header is protected with a single relief valve
(2-SI-439), with a lift setting of 500 psig, located on the system
discharge piping. This relief valve is connected to the RCS Loop 2B
injection line upstream of the LPSI injection valve. It relieves to the
Equipment Drain Sump Tank (EDST). The relief valve has
backpressure compensation with its setpoint based on the LPSI pump
design pressure of 500 psig.
- f. Control and Instruments NONE 10. SDC High Point Evacuation Subsystem
- d. Purpose The High Point Vent and Vacuum Priming System has been installed
to take a suction at the high point loop seal and remove any collected air and non-condensable gases that could threaten prime on LPSI
pump operating in SDC.
PEO-4J e. Design and Operating Characteristics A permanent evacuation system is installed because the common
suction line is routed about 10 inches above the centerline of the hot
leg over the course of its run from the loop to the piping penetration
inside Containment. This elevation difference creates a high point
loop downstream of the motor operated isolation valves but inside
Containment. This loop seal can collect entrained air that could
threaten the prime on a LPSI pump operating in the SDC mode. Air entrainment can occur during conditions when level is lowered in the hot leg. PEO-4J Figure 4 The 12-inch suction line for the Shutdown Cooling System rises to the 6' 8" elevation before dropping down to the 0'6" level containment
penetration. Approximately 27 feet of 12-inch pipe runs horizontally at
the 6' 8" elevation (about 10 inches above the
Figure 13 Lesson Title: Shutdown Cooling System Page 22 of 82 Revision: 4 ID Number: SDC-00-C centerline of the hot leg) creating a significant volume in which air can collect. The evacuation sub-system connects to a 3/4" vent on the
top of this horizontal piping run by means of a flexible stainless steel
hose. The Vacuum Priming System consis ts of a vacuum pump (P-174), a carry over tank, and a vacuum flask. The vacuum pump draws a
vacuum on the carryover tank which is connected to the vacuum
flask. The vacuum in the vacuum flask draws air and other gases
from the SDC system high point vent. Any liquid pulled from the SDC
system is collected in the vacuum flask and if that becomes full, the
liquid overflows to the carry over tank.
This connection is made prior to draining the RCS for the purpose of
establishing RCS level within the hot leg. A check valve, installed
close to the manual vent valve (2-S I-43A), prevents air back-flow into the system and eliminates the need for the operator to manually
control the vent valve position during each evacuation. Any water
collected in the evacuation system is drained to a SIT sample sink in
Containment.
- f. Control and Instruments All components and controls are located within a cabinet located in
the west electrical penetration area on the 14'6" level of Containment.
This location was chosen to limit the radiation exposure during use.
The cabinet is energized by taking a switch, inside the cabinet to ON.
The vacuum pump, P-174, has a START/STOP switch used to
control operation. The system is powered from Lighting Panel L94, supplied by B61. The unit is operated locally whenever reactor level
is lowered below 21 inches above the centerline of the hot leg and the
possibility for vortexing exists.
- 11. Reactor Coolant Sy stem Level Indication
- d. Purpose Reactor Coolant System level indication is required to support
Shutdown Cooling System operation under reduced RCS level
conditions by ensuring adequate monitoring and control of RCS
inventory.
- e. Design and Operating Characteristics Under reduced RCS level conditions, reactor vessel level increases
can result in coolant overflowing through openings, scalding workers
or damaging equipment. Reactor vessel water level decreases of a
few inches threaten core cooling by disabling SDC through air
entrainment. Because of the reduced coolant inventory at these
levels, a loss of SDC can result in rapid heatup rates, boil-off of
reactor coolant, and potential core damage. Under reduced RCS
Lesson Title: Shutdown Cooling System Page 23 of 82 Revision: 4 ID Number: SDC-00-C level conditions, additional attention is required to ensure adequate monitoring and control of RCS inventory.
Two standpipe assemblies are connected to the Loop 1 RCS hot leg
low point drain header. One standpipe contains a thermal dispersion
continuous level sensor (LT-112) which uses a heated/unheated RTD
for readout via the Plant Process Computer. The other (LI-112)
contains a magnetic float that repositions "flags" for local direct visual
indication. On Loop 2 of the RCS an ultrasonic level sensor non-
obtrusively measures level in the hot leg piping. These detectors are zero referenced to the RCS hot leg centerline.
Figure 14 Figure 15 The standpipe level indicators are normally isolated from the Reactor Coolant System in Modes 1 thr ough 4 by manual valves (2-RC-214 and 2-RC-433). These level detectors are connected to this point via
flange adapters and quick disconnects. The high side of these
detectors connects, via a transition tubing assembly, to the Reactor
Vessel head vent, to the Pressurizer vent, and to the inlet of the
Enclosure Building Filtration System fan at 2-EB-86.
Figure 4 f. Control and Instruments The Loop #1 standpipes provide a continuous readout of RCS level from -21" to +99", while the Loop #2 ultrasonic level sensor has a
range of -17" to +21". These are both in reference to the hot leg
centerline. During RCS level changes the ultrasonic level detector
updates immediately if an RCS level change occurs. The response of
Loop #1 RTD level sensor will lag the ultrasonic sensor by
approximately 2 minutes. Direct visual indication of RCS level is provided by the magnetic flags within the Loop #1 standpipe, either locally or by remote television monitoring in the Control Room. This
remote visual indication is designed to be used as a "cross-check" of
the two electronic hot leg sensors.
Figure 15 Both hot leg electronic level instruments send their outputs to the Plant Process Computer for processing and display. The ultrasonic
level indication is calibrated for a water density that corresponds to a
fluid temperature of 110° F. Therefore, the output of the ultrasonic
level detector on Loop #2 must be corrected for any change in the
water temperature. This is automatically accomplished by the Plant
Process Computer.
Figure 16 Figure 17 The Heated Junction thermocouple (HJTC) Reactor Vessel Level Monitoring System (RVLMS) provides reliable indication of reactor
vessel level during Reactor Coolant System drain down evolutions.
HJTCs #4, #5, and #6 correspond to the top, center, and bottom of
the hot leg. This indication system is only available when the Reactor
Vessel head is in place and the HJTCs are electrically connected.
Indication is provided on the Plant Process Computer (PPC) and the Inadequate Core Cooling Monitoring panels in the computer room.
Figure 18 Figure 19 Lesson Title: Shutdown Cooling System Page 24 of 82 Revision: 4 ID Number: SDC-00-C F. OPERATION
- 2. Normal Operation (Shutdown Cooling in Service)
Normal Shutdown Cooling (SDC) operation involves using the LPSI system as a portion of the SDC system. As such, it is routinely
operated when in Modes 4, 5, and 6.
In Modes 4 and 5 Technical Specifications require two operable
cooling loops. If RCPs and steam generators are inoperable, then
both SDC trains are required to be operable.
T/S 3.4.1.3a In Mode 6 Technical Specifications require two SDC loops to be
Operable if Vessel water level is not at or above the vessel flange.
TS 3.9.8.2 In Mode 6 Technical Specifications require a Shutdown Cooling loop
must be in operation unless core alterations in the vicinity of the RCS
hot leg requires flow to be stopped. In this case flow can be secured
for up to one hour per 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> period.
T/S 3.9.8.1 Both LPSI trains contain cross-connections with the Containment
Spray System for Shutdown Cooling operation.
The LPSI system has interconnections with the Chemical & Volume
Control System to provide purification and inventory control.
The LPSI system has interconnections with the Spent Fuel Pool
Cooling (SFPC) system to provide supplemental cooling during
periods of high heat load on the SFPC system.
The LPSI system is used for some infrequent non-routine operations
such as transferring water between the Refueling Water Storage
Tank (RWST) and Refueling Cavity and for Recirculation of the
RWST. The LPSI pumps, as a portion of the Shutdown Cooling
system, can also be used to fill the SITs.
An engineering evaluation of LPSI pump operations has determined
that operation of the LPSI pumps at low flows for extended periods of
time (greater than 30 minutes) has the potential to cause severe pump damage. When the LPSI pumps are operated at flows significantly less than design flow, internal recirculation flows develop
which cause cavitation, pressure pulsations, unbalanced forces, and
vibration. These effects can lead to erosion, unstable head-flow characteristics, and failures of pump internals, seals, and thrust
bearings. Extended operation at low flow can progressively damage a
pump with no evidence from performance testing until eventual
failure. Engineer's Memo TS2-97-530 The minimum flow recirculation is sized only to prevent short term overheating of the pump and is not designed for long term operation.
For short term testing, flow provided by the recirculation line is
acceptable for periods of 15 to 30 minutes.
Lesson Title: Shutdown Cooling System Page 25 of 82 Revision: 4 ID Number: SDC-00-C Extended operation at low flow will not result in noticeable short term degradation, but will result in accelerated wear of pump components.
The decision to operate the pumps for longer or lower flow rates than
recommended must be made carefully. An immediate plant safety
issue takes precedence over meeting the recommended flow rates.
However, meeting the recommended flow rates clearly takes
precedence over operations of convenience. In all cases, for pump operation below design flow, the pump flow rate should be as high as reasonably achievable up to the design flow rate.
- d. Precautions The following precautions, their bases, and parameters used for monitoring the conditions (if available) are associated with the SDC
System: OP 2310 RCS heatup and cooldown rates shall be maintained as specified in SP 2602B, "Transient Temperature, Pressure Verification."
RO-4 Basis -- Technical Specifications require that temperatures will be determined at least once every hour. Using SP 2602B allows the
operator to meet the surveillance requirement and enables closer
trending by determining the temperatures at shorter time intervals.
When returning "SDC SYS HX FLOW CNTL, SI-657," to the air operated mode, to prevent a restriction to closing, the handwheel must be locked in full up position.
PEO-7 Basis -- A manual handwheel was installed on the HX flow control valve because the valve fails closed in the event of a loss of either
Instrument Air or control power resulting in a loss of shutdown
cooling. The manual actuator for 2-SI-657 is reverse acting, i.e.,
clockwise rotation of the local manual handwheel opens the valve by
pushing down on the actuator and the valve stem. During normal
SDC operation, when the valve is in the air operated mode, the manual operator is disengaged and locked in the full out position
which allows unimpeded control of flow through the SDC heat exchangers by positioning flow control valve (2-SI-657) from Main
Control Board C0-1.
Lesson Title: Shutdown Cooling System Page 26 of 82 Revision: 4 ID Number: SDC-00-C During operation of SDC, the following limits shall not be exceeded: RCS pressure greater than 265 psia, indicated on pressurizer pressure low range instruments, P-103 and P103-1 RCS T HOT greater than 300° F LPSI pump discharge pressure greater than 500 psig LPSI pump motor amps less than 52 amps LPSI pump flow less than 4,000 gpm SDC flow through each SDC heat exchanger greater than 4,800 gpm [Ref. 6.10] RBCCW flow through each SDC heat exchanger greater than 4,800 gpm [Ref. 6.10] RBCCW header flow greater than 8,000 gpm RO-4 Basis -- The Shutdown Cooling System is designed to withstand a static pressure of 300 psig plus an additional 200 psid of head
added by an operating LPSI pump. Relief valves on the suction
piping are set for 300 psig, and the pump discharge piping is
protected by relief valves set to lift at 500 psig. Additional over
pressure protection is provided by an interlock which prevents the RCS outlet valves (2-SI-652 & 2-SI-651) from being opened when Pressurizer pressure exceeds 280 psig. The 300 psig static suction pressure that the Shutdown Cooling System is designed to
withstand is the sum of 265 psia Pressurizer pressure plus an
additional 35 psi of static pressure due to elevation head.
PEO-8 The limit of 4,800 gpm SDC flow through a single SDC heat exchanger is to prevent tube side HX damage. The SDC flow can
be read from the CS FLOW indicators (FI-3023, 3024) on C-01 or
from the PPC.
The limit of 4,800 gpm RBCCW flow through a single SDC heat exchanger is to prevent shell side HX damage. The RBCCW flow can be read from the SDC HX A(B) RBCCW OUT FLOW indicators (FI-6042, 6043) on C-06 or from the PPC.
Limiting RBCCW header flow to 8000 gpm prevents run out of the
RBCCW pump.
The SDC system is potentially radioactive. Radiological procedures must be strictly adhered to during any venting, draining, or other
operations which could result in radiation exposure or contamination of personnel.
PEO-7 RO-4 Basis -- The RWST is used as the supply for filling the LPSI system piping. The water flowing through the SDC system is RCS water.
This is contaminated water and when vented or drained must be
Lesson Title: Shutdown Cooling System Page 27 of 82 Revision: 4 ID Number: SDC-00-C contained to prevent an uncontrolled radioactive release. As this water is being vented it is possible for airborne contamination
levels to increase requiring air monitoring and proper breathing
apparatus.
The SDC System may be secured for up to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> per 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> period, during core alterations in the vicinity of the reactor vessel
hot legs. RO-4 Basis -- This is a footnote to the Tech Spec requirement for SDC operability to allow for fuel movement without the induced
movement of refueling mast/fuel assemblies due to SDC flow.
One SDC train shall have an OPERABLE diesel generator. The other train of SDC may be supplied from its normal power supply (e.g. diesel generator is not required to be OPERABLE).
RO-4 Basis -- This meets the electrical power supplies required by Tech Specs and still allows for flexibility of maintenance during outages.
With fuel in the reactor vessel, RCS temperatures shall be maintained greater than or equal to 68° F [Ref. 6.5].
RO-4 Basis -- This is the minimum temperature that the reactor vessel will experience deformation prior to a fracture of the vessel.
To minimize the consequences of boron dilution accidents, SDC flow shall be maintained greater than or equal to 1000 gpm based on the sum of LPSI injection flow indicators. [Ref. 6.6].
RO-4 Basis -- This precaution applies only when SDC is initiated without concurrent RCP operation. Maintaining flow greater t han or equal to 1000 gpm ensures sufficient coolant circulation through the reactor
core to minimize the effects of a boron dilution incident and to
prevent boron stratification. This flow can be read on SDC FLOW
indicator (FI-306) on C-01 or from the PPC.
The following valves are reverse operating valves; counterclockwise rotation of the handwheel closes it and clockwise
rotation of the handwheel opens the valve: SDC System total flow valve, 2-SI-306 SDC System heat exchanger flow control valve, 2-SI-657 SDC to SFPC stop, 2-RW-15 PEO-7 Basis -- Because these valves are reverse operated, counterclockwise rotation of the handwheel closes the valves and
clockwise rotation of the handwheel opens the valves. This is the
opposite of standard engineering practices for manual valve operation. Care must be taken w hen operating these valves manually to avoid over-torquing and damaging valve components.
When SDC is not in service, the solenoid valve located in the
pneumatic signal line to the diaphragm of the actuator for SI-306 is
Lesson Title: Shutdown Cooling System Page 28 of 82 Revision: 4 ID Number: SDC-00-C electrically disabled to prevent air pressure from reaching the diaphragm. With no air applied, spring force is sufficient to hold the
valve in the full open position. The manual operator on the opposite
side of the shaft can be manually engaged and dis-engaged from the
valve plug shaft by means of a coupling pin. When engaged, this
operator has sufficient mechanical advantage to over-ride operation
of the pneumatic actuator in all cases. This handwheel is normally locked to prevent inadvertent operation.
A mechanical stop has been placed on "SDC SYS TOTAL FLOW, SI-306" to limit flow and prevent run out of LPSI pumps during SI
operation. It is still necessary to throttle LPSI injection valves. Total SDC flow must not exceed 4000 gpm during single pump operation or 7000 gpm during 2 pump operation [Ref. 6.4 and 6.6].
RO-4 Basis -- Total Flow control Valve, 2-SI-306, has a mechanical stop that limits how far the valve will open (approximately 50 % open). The
discharge of both LPSI pumps pass through the flow control valve
during SIAS injection. The purpose of the mechanical stop is to limit
the LPSI flowrate, preventing runout of the LPSI pumps during SIAS
injection. During Shutdown Cooling operation, the LPSI injection
valves are maintained in a throttled position which ensures that a single LPSI pump will not reach run-out conditions.
IF in MODE 4 or higher with the following open, a dedicated operator shall be stationed: SIT injection header recirculation stop, 2-SI-463 PEO-7 RO-4 Basis -- The SIT injection header recirculation stop, 2-SI-463, and SDC System suction isolation valve, 2-SI-709, are containment isolation valves that are required to be closed and locked in
Operational Modes 1 through 4 for Containment integrity. However, the valves may be opened on an intermittent basis under
administrative control (dedicated operator), as specified in
Technical Specifications LCO, 3.6.3.1, Table 3.6-2.
Operation of LPSI pumps at less than 1,650 gpm should be minimized. Prolonged operation of LPSI pumps at reduced flow, less than 1,650 gpm, can cause premature wear of pump components. Operation of LPSI pumps at less than 100 gpm (minimum flow requirement) is prohibited.
RO-4 Basis -- An engineering evaluation of LPSI pump operations has determined that operation of the LPSI pumps at low flows for
extended periods of time (greater than 30 minutes) has the potential
to cause severe pump damage. When the LPSI pumps are operated
at flows significantly less than design flow, internal recirculation flows
develop which cause cavitation, pressure pulsations, unbalanced
forces, and vibration. These effects can lead to erosion, unstable head-flow characteristics, and failures of pump internals, seals, and
Lesson Title: Shutdown Cooling System Page 29 of 82 Revision: 4 ID Number: SDC-00-C thrust bearings. Extended operation at low flow can progressively damage a pump with no evidence from performance testing until eventual failure. This flow can be read on SDC FLOW indicator (FI-
306) on C-01 or from the PPC. System adjustments covered in this procedure can significantly reduce core heat removal for short periods of time. Total loss of core heat removal may, depending on power history, cause a RCS heatup of up to 5° F in one minute. To minimize impact, careful coordination of activities is required to reduce the time required for adjustments.
PEO-7 RO-4 Basis -- Due to the integrated relationship between the RCS, SDC, RBCCW systems, and their interconnected systems a change in
any parameter or configuration has the potential to ultimately affect
core heat removal capabilities. All actions must be carefully
planned, slowly performed, and system changes anticipated prior
to and during plant activities.
- e. Startup The SDC system can be aligned and operated either with or without
concurrent RCPs operating during the cooldown. In order to place
SDC in service the following major evolutions associated with the
SDC system are performed:
PEO-9 Preliminary SDC preparations Boron equalization SDC system warmup SDC Initiation
- 1. Preliminary SDC preparations Preparations for Shutdown Cooling System initiation are commenced as soon as Mode 3 is entered and primary plant pressure has been
decreased to less than 1750 psia. The preliminary SDC preparations
are the same, independent of whether or not RCPs will be left
running. The following major actions are performed in preparation of
starting up SDC:
- 1) The "Load-shed" trip, generated from the "Main Generator Final Coastdown Circuit is blocked to prevent LPSI pumps
from tripping during turbine testing or 345 KV breaker
operation.
- 2) RBCCW is manually aligned to the SDC heat exchangers, and ESF Room Ventilation is placed in service on room(s) in which
LPSI pumps will be operated.
After the preliminary preparations are completed the decision is made
on whether the SDC system cooldown will be conducted with or
Lesson Title: Shutdown Cooling System Page 30 of 82 Revision: 4 ID Number: SDC-00-C without concurrent RCP operations. If the decision is made to perform SDC operations with concurrent RCP operation than the
SDC evolutions performed include the applicable actions for SDC
system alignment, warmup, and initiation. If the decision is made to
perform SDC operations without concurrent RCP operation than the
SDC evolutions performed include the applicable actions for SDC
system alignment, boron equalization, warmup, and initiation.
Prior to aligning SDC to the RCS, the required HPSI pump is
placed in the PTL position to prevent an inadvertent start from
overpressurizing the SDC piping.
- 2. Preparation For SDC Operation With Concurrent RCP Operation Because the SDC system will be providing cooling flow with RCP flow
through the RCS the preparations and warmup of the SDC system
are not as time consuming or restrictive as they are without RCP
operation. With RCP operation there is better mixing and less
thermal transients to the RCS and especially the reactor vessel belt
line. The following major actions are performed in preparation of SDC
operation with concurrent RCP operation:
- 1) The SDC Total Flow Control Valve is placed in manual remote control. Figure 12 2) The system is recirculated to partially warmup the SDC system by opening the SDC warm-up valve (SI-400) and establishing
a closed loop flow.
- 3) Warmup is stopped after a concurrent temperature and pressure rise is observed. A concurrent pressure and
temperature increase indicates a "tight" system. A full warmup
of the SDC system is not required when initiating Shutdown
Cooling with concurrent RCP operation.
- 4) RBCCW flow is established through the shell side of the Shutdown Cooling Heat Exchanger(s).
During the warmup, one LPSI pump is in operation and can heat-up
the system at about 11° F/hr. Operation of two LPSI pumps in this
line-up is prohibited in order to prevent operation of pumps with
insufficient cooling flow through them. This could occur if the
discharge check valve on one of the two operating LPSI pumps were
to be forced closed as the result of unbalanced LPSI pump
performance. If this were to occur, the pump could overheat resulting in severe damage.
After the SDC preliminary preparations have been completed, at the appropriate time in the cooldown evolution the SDC system is placed
Lesson Title: Shutdown Cooling System Page 31 of 82 Revision: 4 ID Number: SDC-00-C in service concurrent with RCP operation. 3. Shutdown Cooling Initiation With Concurrent RCP Operation The SDC system is placed in operation when RCS Tcolds are between 240 to 260 °F with RCS pressure less than 265 psia. Also, the SDC boron concentration must be 1.1 times the required RCS
Cold Shutdown Concentration. This requirement will prevent the SDC
system from diluting the RCS below the Cold Shutdown
Concentration. The following major actions are performed to initiate
SDC with concurrent RCP operation:
- 1) Prior to placing SDC in operation, all SIT isolation valves are checked closed, and the SIT isolation valve circuit breakers
are red tagged OFF.
Figure 1 2) Provide a suction from the RCS via 2-SI-651 and 2-SI-652, and then cracking open one of 4 LPSI throttle valves (2-SI-615, 625, 635, or 645) as indicated by dual indication on C-01.
- 3) Monitor pressurizer level for indications of leakage from the SDC as indicated by a lowering pressurizer level when the
SDC system is opened to the RCS.
- 4) One LPSI pump is started. 5) When SDC to RCS temperature (T351Y) is within 20° F of hot leg temperature, the desired LPSI flow is established by
throttling open all four of the LPSI injection valves.
- 6) RBCCW flow is then adjusted to the required value. 7) SDC cooling flow through the Shutdown Cooling Heat Exchangers is initiated (using HIC- 3657) to obtain a 40° F delta T between SDC suction temperature (T351X) and SDC
return flow (T351Y).
Once SDC cooldown has been established the operators must
ensure that RCS system response is within Technical Specification Cooldown limits. SDC flow through the SDC HXs is controlled to
control the cooldown rate. If required by decay heat, a second
LPSI pump is started and the LPSI injection valves are throttled to
maintain flow limits.
- 4. Preparation For SDC Operation Without Concurrent RCP Operation If the decision has been made to place SDC inservice without
concurrent RCP flow then additional requirements with SDC boron
equalization and warmup are performed. The SDC system must be
recirculated to ensure that the boron concentration within the
Shutdown Cooling System piping is equal to, or greater than the Figure 20 Lesson Title: Shutdown Cooling System Page 32 of 82 Revision: 4 ID Number: SDC-00-C existing RCS boron concentration. This ensures that an inadvertent dilution of the RCS and corresponding loss of shutdown margin does
not occur when system flow is initiated. This is performed prior to
decreasing RCS pressure below the shutoff head of the LPSI pumps (approximately 220 psig), ensuring that the SDC system does not
inject water into the RCS while recircing to the RWST.
The following major actions are performed for preparing the SDC
system for operations without concurrent RCP operation:
- 1) Ensure the Safety Injection Actuation Signals are blocked then align and vent the SDC system for boron equalization.
- 2) The SDC system is aligned for recirculation back to the RWST. 3) The Safety Injection Tank (SIT) isolation valves (2-SI-614, 624, 634, & 644) are closed to prevent discharging the Safety
Injection Tanks, via the recirculation header, to the RWST.
- 4) The recirculation lineup is completed and a LPSI pump is started. 5) After 10 minutes operation the first LPSI pump is shutdown and the idle LPSI pump is started to ensure the boron
concentration is equalized in all the SDC system piping.
- 6) When SDC boron concentration has been equalized the LPSI pump is shutdown and the recirculation path secured.
The boron equalization flow path recirculates the entire SDC
system. Water is taken from the RWST and pumped through each
LPSI pump and SDC heat exchanger. The discharge from the
common discharge header goes through all four LPSI Injection
Valves. The four Check Valve Leakage Drain Stop Header valves
are opened which aligns the LPSI injection lines to the SIT injection
header recirculation line. The water flows through this line back to the RWST.
PEO-2E, RO-1E During this evolution, because the SITs are isolated, Boron Equalization must be completed in the minimum time possible. In no
case may this time exceed 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. Minimizing the period of time
these tanks are isolated is done due to concern for a LOCA occurring
between 1750 and 600 psia.
After Boron Equalization has been established the SDC is then
warmed up prior to being placed in service.
Lesson Title: Shutdown Cooling System Page 33 of 82 Revision: 4 ID Number: SDC-00-C 5. System Warmup Without Concurrent RCP Operation Warm-up of the Shutdown Cooling Systems is commenced after Chemistry has confirmed that the boron concentration in the Shutdown Cooling System is equal to or greater than the existing
RCS boron concentration. The following major actions are required
to warmup the SDC system prior to placing it in service without
concurrent RCP operation:
- 2) The SDC warm-up valve (SI-400)is opened and the closed loop flowpath is establish.
- 3) One LPSI pump is started to commence SDC system warmup. 4) Continue running one LPSI pump until the SDC to RCS Temperature (T351Y) is greater than 150° F.
When the SDC to RCS Temperature (T351Y) is greater than 150° F
and a LPSI pump is operating, the SDC system can be aligned to
commence cooling the RCS without concurrent RCP operation. The
150 F value bounds the The concern when initiating SDC flow without concurrent RCP
operation is the rate of change in the temperature of the water to
which the reactor vessel belt line is exposed. When SDC is first
initiated the temperature of the water near the belt line changes from a value in the range of 230 to 260 F to 150 F. This cooldown rate exceeds that allowed by Tech Specs. This exceedence requires the performance of an Engineering evaluation. Since this evaluation
must be made each time SDC is initiated without concurrent RCP operation Engineering has generated a generic evaluation to cover this event in advance. The 150 F limit ensures that the bounding assumption made regarding initiation temperature is valid. Therefore the generic evaluation can be used to fulfill the Engineering
evaluation for each occurrence.
- 6. Shutdown Cooling Initiation Without Concurrent RCP Operation The Shutdown Cooling System is placed in operation after boron equalization and system warmup have been completed and the RCS
is less than 260° F (preferably approximately 230° F) and less than
265 psia.
The following major actions are performed to initiate SDC without
concurrent RCP operation:
- 1) SDC system alignment for initiation is verified. 2) All SIT isolation valves are closed, and the SIT isolation valve Lesson Title: Shutdown Cooling System Page 34 of 82 Revision: 4 ID Number: SDC-00-C circuit breakers are red tagged OFF prior to placing SDC in operation. 3) The operating RCPs are stopped and RCS pressure is reduced to less than 265 psia using auxiliary spray.
- 4) The SDC system suction isolation valves (SI-651, 652) are opened. 5) The SDC total flow control valve is opened and the SDC HX flow control valve is closed.
- 6) RBCCW flow is established through the SDC HXs. 7) All four LPSI injection valves are throttled open (400 - 600 gpm each) to establish initial flow to RCS.
- 8) When SDC to RCS temperature (T351Y) is greater than RCS Tcold temperatures the SDC warmup valve (SI-400) is closed.
- 9) The SDC injection valves are throttled open (800 - 1000 gpm each) to establish total system flow of 3500 - 4000 gpm to
RCS. 10) RCS cooldown is established by adjusting SDC HX and RBCCW flow rates.
- 11) The LPSI minimum flow manual isolation valves (SI-449/450) are closed and the minimum flow valves (SI-659/660) are re-
opened to maintain a minimum flow path for the HPSI pumps.
The plant can then be cooled down at a rate to be established by the
Control Room Operator but not to exceed 50° F/hr ( Less than or
equal to 50° F/hr below 220° F).
Any time any of the following parameters are changed, clear
strategies need to be developed and discussed:
SDC Total Flow Control valve position.
SDC HX Flow Control Valve position.
SDC HX manual outlet valve's position.
RBCCW flows and temperature changes.
Changing the position of SI-306, SDC Total Flow Control Valve, affects the system pressure upstream of the valve. Specifically, if SI-306 is throttle in the closed direction then the upstream pressure rises
and the down stream pressure lowers. This additional differential
pressure is felt across the parallel path that includes the SDC heat exchangers and SI-657, SDC HX Flow Control Valve. This pressure
rise is sensed at the inlet to the SDC heat exchangers and SI-657.
Since the position of SI-657 is controlled from C01, without operator action the flow through the heat exchangers and SI-657 will rise when
Lesson Title: Shutdown Cooling System Page 35 of 82 Revision: 4 ID Number: SDC-00-C SI-306 is throttled closed. This will cause SDC return temperature to lower. If SI-306 is throttled open the flow through the SDC heat
exchangers will lower causing SDC return temperature to rise. 7. Shifting SDC Heat Exchanger Operations When shifting from two SDC HX operation to one SDC HX operation
the following conditions should be considered:
It is preferable to do this while maintaining a steady RCS temperature. This evolution could cause a change in RCS temperatures due to removing the HX. If RCS temperatures are
already changing, this activity could increase the temperature
changes. RO-5A It is preferable to use only one LPSI pump while performing this evolution. When going from two HXs to one HX the possibility exists to exceed the maximum SDC flow rate through the one HX
before completing the evolution.
RO-5B This evolution can not be performed during concurrent RCP operation. With an RCP in operation, one SDC HX can not
remove the pump heat and maintain core temperatures.
RO-5C If RCS temperature is low and decay heat load is high performing this evolution may cause RCS temperatures to rise. The operator should be aware that with high decay heat loads, one HX may be
operating close to its thermal capacities.
RO-5D Shifting from two HXs to one HX consists of the following major
actions: 1) RBCCW flow to the HX left inservice is increased to maintain RCS temperatures.
- 2) The LPSI inlet valve, outlet valve, and RBCCW outlet valve for the HX being removed from service are closed.
- 3) SDC temperatures and flows are monitored and adjusted as necessary.
Placing a second SDC HX in service should be a slow controlled
evolution. SDC temperatures can change drastically by even minute
changes in SDC parameters .
Shifting from one HX to two HXs consists of the following major
actions: 1) Boron concentration in idle components is verified greater than or equal to required RCS boron concentration.
Lesson Title: Shutdown Cooling System Page 36 of 82 Revision: 4 ID Number: SDC-00-C 3) PPC trend of SDC data is established to monitor system changes. 4) RBCCW flow is established through the idle HX. 5) SDC flow through the idle HX is established by opening the SDC HX outlet isolation valve.
- 6) SDC and RBCCW flows are modulated to maintain desired SDC and RCS temperatures Whenever SDC HXs are shifted, it is important to ensure that the maximum SDC flow (4800 gpm) and RBCCW flow (4800 gpm) through a single HX not be exceeded. Also, to prevent exceeding the
applicable heatup and cooldown rates the SDC temperature to the
RCS should be as stable as possible prior to starting the evolution.
- f. Power Operation The SDC System is not operated when the plant is at power.
However, Technical Specifications require that the LPSI system
components that are normally part of the ECCS must be operable
whenever the plant is in Modes 1, 2 or 3* (* RCS pressure greater
than 1750 psia).
An Administrative requirement also exists to have these components
operable whenever the primary plant pressure is greater than 400
psia. This maximizes the availability of LPSI to inject should a Loss of
Coolant Accident occur while at reduced RCS pressures.
- g. Shutdown (Securing SDC)
At the completion of the plant shutdown preparations are made to
commence a plant heatup and startup. At the appropriate time the
SDC system is shutdown and realigned for heatup/startup.
The following major evolutions are performed to shutdown the SDC
system and align its components for plant operation:
PEO-10 SDC flow is terminated.
Safety injection headers are recirculated following SDC termination.
- 1. Shutdown Cooling Termination The Shutdown Cooling System is removed from operation when Shutdown Cooling inlet temperature is between 200 °F and 240 °F. The 200 F limit protects the piping between SI-651 and SI-709 from rupturing in a post LOCA environment. This section of pipe is not
protected by a relief. By ensuring the temperature of the water in pipe when isolated is greater than 200 F the thermal expansion of that water volume will not rupture the pipe. To prevent thermal binding of SDC suction valves 2-SI-651 and 2-SI-652 the water temperature
Lesson Title: Shutdown Cooling System Page 37 of 82 Revision: 4 ID Number: SDC-00-C in the pipe must be less than 240 F when isolating SDC. This ensures the valves will not bind after they cool to ambient temperatures. The following major actions are performed to terminate SDC flow: 1) The SDC HX flow control valve is closed. 2) The running LPSI pump is shutdown. 3) The LPSI injection valves and the SDC suction isolation valves are closed.
- 5) The SDC system is aligned to flush the system with RWST water to ensure boron concentration is at the RWST value.
- 6) Each LPSI pump is run for 15 minutes on recirc back to the RWST. 7) The LPSI and Containment Spray systems are aligned for normal at power operation.
After the LPSI pumps are recirculated/flushed back to the RWST the
Safety Injection Headers are recirculated/flushed to ensure their
boron concentration is at RWST concentration. Normal at power
operation requires that the ECCS system inject borated water at
greater than 1720 ppm on a Safety Injection actuation.
RO-6 2. Recirculating SI Headers Following Termination of SDC The Safety Injection (SI) headers are recirced when RCS pressure is
greater than 295 psia and the LPSI and CS systems have been
aligned for normal power operation. Prior to initiating recirculation the
SIT outlet valves are closed to prevent draining SITs to the RWST via
the recirculation line.
The following major actions are performed to recirculate the SI
headers following termination of SDC flow:
- 1) The recirculation header is aligned for flow back to the RWST. 2) One LPSI pump is started to pressurize the system. 3) The SDC heat exchangers and their piping are flushed through SI-460 at 1500 gpm for 15 minutes.
- 4) The #1 and #2 SIT outlet isolation valves are closed. Then SI-615 and SI-625 are opened. Next SI-618 and SI-628 are
throttled open to obtain approximately 15 gpm flow back to the
RWST for at least 15 minutes. This action can be done while
flowing water through SI-460.
Lesson Title: Shutdown Cooling System Page 38 of 82 Revision: 4 ID Number: SDC-00-C 5) The LPSI pumps are swapped to flush the pump. SI-460 is throttled again to 1500 gpm for 15 minutes.
- 6) The #3 and #4 SIT outlet isolation valves are closed. Then SI-635 and SI-645 are opened. Next SI-638 and SI-648 are throttled open to obtain approximately 15 gpm flow back to the
RWST for at least 15 minutes. This action can be done while
flowing water through SI-460.
- 7) Upon completion of the flush the pump is stopped and the valves properly aligned.
When flushing operations have been completed, the RWST is
sampled to ensure that it has not been diluted to below the required
boron concentration (greater than 1720 PPM) for power operation.
- 3. Restoration of SIAS Open Capability to LPSI Injection Valves when exiting Reduced Inventory Operations When Reduced Inventory Operations was entered the SIAS signal
was prevented from positioning the LPSI Injection Valves on an
inadvertent SI actuation signal. This protected the SDC from the
excessive flowrates that would have occurred if the LPSI valves were
to get an SIAS actuation signal during reduced inventory operation.
When reduced Inventory Operations is exited the SIAS open
capability is restored to the LPSI injection valves. The Maintenance
department removes the jumpers and reinstalls the lifted leads for
each of the LPSI injection valves. When the SIAS open capability has
been restored, the operators will conduct the SIAS Operability test for
all four LPSI Injection Valves.
- 3. Abnormal Operation
- d. Loss of Shutdown Cooling The loss of Shutdown Cooling requires that timely action be taken by
the operator to restore cooling to the core. Prompt restoration of cooling flow will help to avoid core boiling. Loss of shutdown cooling
has been most commonly initiated by the accidental closure of a SDC
suction valve, low reactor vessel level resulting in a loss of LPSI pump
suction, or an inadvertent trip of the running LPSI pump. The
inadvertent closure of a suction valve would require a manual trip of the running pump(s) and termination of any evolutions in progress (such as "Excess Letdown", filling a SIT, etc.). Guidance is provided
in AOP 2572 (and OP 2310 and 2306) on the actions required to be
taken by the operator for any of these events.
- e. Additional Purification While on SDC, purification of the RCS coolant and refuel pool water may be accomplished utilizing the ion exchangers in the CVCS Figure 7 Lesson Title: Shutdown Cooling System Page 39 of 82 Revision: 4 ID Number: SDC-00-C system. This process is referred to as "Additional Purification." The cross-connect between the Shutdown Cooling System and the Chemical & Volume Control System (CVCS) allows reactor coolant
from the outlet of the SDC heat exchanger to enter the inlet of the
letdown heat exchanger (via 2-SI-040). This provides additional
assurance that the fluid temperature at the inlet of the ion exchangers will be maintained at less then 135° F for protection of the resin.
Additionally, if the fluid temperature was to exceed 140° F, then the ion exchangers will be automatically bypassed.
In the Additional Purification mode, flow through the CVCS system filters and ion exchangers is limited to less then 128 gpm by
controlling the position of the back pressure regulators (2-CH-201
P/Q). The coolant is then returned to the Shutdown Cooling System
at the LPSI pump suction via 2-CH-024.
- f. Excess Letdown When RCS pressure is less than 265 psia, insufficient differential
pressure exists to drive much letdown flow through the CVCS flow
path. The interconnection between the SDC heat exchangers and
the letdown heat exchanger (via SI-040) is used to provide additional, or "excess," letdown capability.
Figure 7 The driving head for the "Excess Letdown" flow path is provided by
the LPSI pump that is in operation for Shutdown Cooling. The flow
path in this line-up is similar to that used for "Additional Purification" with the exception that flow is not returned to the LPSI pump suction.
The flow is either directed to the VCT or CLRW. Aligning the flow to
VCT allows the Charging pumps to inject the water back to the RCS.
This path allows reactor coolant to be drained to the CLRW System at approximately the same rate that could be achieved if the RCS were at normal operating pressure.
- g. Supplementing Spent Fuel Pool Cooling Periodically during the operating lifetime of the plant, it may be necessary to perform a complete core off-load from the reactor vessel
to the Spent Fuel Pool. This would impose a heat load in excess of
the design capacity on the cooling capabilities of the Spent Fuel Pool
Cooling System. If this were to occur, then the Shutdown Cooling
System would be used to supplement the Spent Fuel Pool Cooling
System. Figure 9 Flow between these two systems is aligned via a supply spool piece
located on the discharge of SDC heat exchanger (between 2-SI-458
& 2-RW-11) and a return spool piece to the LPSI pump suction (between 2-SI-442 & 2-RW-15). In this alignment both the reactor
vessel and Spent Fuel Pool Cooling System may be in parallel with
Lesson Title: Shutdown Cooling System Page 40 of 82 Revision: 4 ID Number: SDC-00-C the Shutdown Cooling System.
While operating in this alignment, care must be taken to maintain the following: 1. SFP temperature at less than 140 °F 2. SFPC System pressure less than 30 psig
- 3. LPSI pump amps less than or equal to 52
- 4. LPSI pump flow (SDC and SFPC supplemental) less than 4000 gpm The SFP suction lines extend approximately six inches below the surface of the spent fuel pool. Due to the large flow rates of the SDC
system it is possible to create a vortex action at the inlet to the suction
lines. The formation of a vortex can result in voiding and air binding
of the LPSI pumps. Proper SFP level (between 36' 8" and 37') will
prevent air entrainment of the LPSI pumps. Oscillations in the LPSI
pump discharge pressure and LPSI pump amps are indications of air binding in the pump.
RO-7 h. Filling Safety Injection Tanks Filling of the Safety Injection Tanks can be accomplished while the Shutdown Cooling System is in operation without securing any portion
of the Shutdown Cooling System. This is normally performed
following a refueling outage and when the SITs have been drained for
maintenance.
Figure 10 If all the SITs have been drained, the tanks are filled sequentially to
various levels. The SITs are filled by opening its Fill and Drain Valve
and then opening its Vent Valve. Levels in the SIT ,the refueling
cavity, and/or RWST are closely monitored during each tank filling
evolution.
Once the SITs have been filled, they are sequentially pressurized with
nitrogen and the water is sluiced between them to equalize level and
pressure.
- i. Transferring Water Between the RWST and the Refueling Cavity The Shutdown Cooling System can be used for some infrequently
performed, non-routine operations such as transferring water between
the RWST and Refueling Cavity. A variation of this line-up can also
be used to recirculate and/or heat the RWST.
The LPSI pumps provide the preferred method for filling the refueling
cavity from the RWST. However, care must be taken since the high
flow rates that occur when using this method may cause decreased
clarity within the Refueling Pool and increased airborne activity within
Containment. These problems are a result of "CRUD" breaking
Lesson Title: Shutdown Cooling System Page 41 of 82 Revision: 4 ID Number: SDC-00-C loose in the vessel under the high flow conditions imposed. Filling of the Refueling Cavity is terminated when the level in the Refueling Pool reaches 36' 6" or the RWST level drops to 6%.
The transfer of water from the refueling cavity to the RWST can also
be accomplished using SDC. The use of the Shutdown Cooling
System in this capacity allows for the rapid transfer of water, but it
does not allow for purification of the water during the process.
Therefore unless high flow rates are desired the Spent Fuel
Purification system should be used for this task.
- j. Alternate flowpath taking suction from the SFP Either SDC pump can be aligned to take suction from the SFP
through 2-RW-11 and 2-SI-442 instead of the normal suction
flowpath. When using this flowpath, flow restrictions in the procedure
must be adhered to in order to avoid vortexing at the suction. The
evaluation for this evolution assumes that this option would not be
used until after the fuel shuffle which would provide at least 14 days
from shutdown for decay heat to decrease. Additionally, core alterations shall be suspended while this alignment is in use. This flow path should normally be used for short periods, only, approximately
12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> or less. If this flowpath is to be used for >24 hours or the
core has not been shutdown for >14 days, further evaluation must be
done prior to using this option.
3.9.8 4. Maintenance and Testing
- d. Monthly Testing On a monthly basis the LPSI system components must be proved operable to satisfy the requirements of tech specs.
The following monthly tests are performed: Checking the electrical alignment of the LPSI pumps.
Checking the LPSI valve alignment to ensure an operable flowpath.
Checking the operability of the LPSI injection valves.
- e. Quarterly Testing (I nservice Testing)
On a quarterly basis the LPSI pumps are run and operational data is
taken to determine operational readiness and detect degradation of
the LPSI pumps, per tech spec requirements.
The quarterly test involves: 1. Isolating the LPSI flowpath to the RCS Lesson Title: Shutdown Cooling System Page 42 of 82 Revision: 4 ID Number: SDC-00-C 2. Start the LPSI pump on recirculation 3. Measure and record recirculation flow, pump D/P, and pump vibration data When the LPSI pumps are aligned for SDC the discharge check valves are tested quarterly for closure and tightness.
This quarterly test involves: 1. Ensure LPSI pump operating on SDC. 2. Check flow greater than 3800 gpm. 3. Shift LPSI pumps and check for reverse rotation of stopped pump. 4. Shift LPSI pumps again and check for reverse rotation of the opposite pump.
- f. Cycle Testing At least once per cycle (18 months) the LPSI system is tested to verify
that it is capable of performing its design functions, per tech spec
requirements.
The following cycle tests are performed: LPSI injection valves are cycled in manual.
LPSI pump high flow inservice test.
- 5. Administrative Requirements
- d. Technical Specifications The following Technical Specifications are associated with the LPSI
subsystems of the ECCS:
RO-8 3.3.2 ESAS Instrumentation 3.4.1.3 and 3.4.1.4 Coolant Loops and Coolant Circulation 3.5.2 ECCS Subsystems T-avg 300° F 3.9.8 Shutdown Cooling and Coolant Circulation TRM 3.1.2.7 The Technical Specifications associated with the LPSI system
components ensure that sufficient LPSI flow will be available in the
event of a LOCA assuming the loss of one facility LPSI system
through any single failure consideration. Either LPSI train operating in
conjunction with the other ECCS systems is capable of supplying
sufficient core cooling to limit the peak cladding temperatures within
acceptable limits for all postulated break sizes ranging from the double ended break of the largest RCS cold leg pipe on downward.
RO-9 RO-10 Lesson Title: Shutdown Cooling System Page 43 of 82 Revision: 4 ID Number: SDC-00-C The RWST has minimum limits on the tank volume and boron concentration. The limits ensure that sufficient water is available
within containment to permit recirculation cooling flow to the core and
that the reactor will remain subcritical with all rods inserted except for
the most reactive rod stuck out.
In mode 4 the Tech Specs specify that two loops of trains consisting
of any combination of RCS loops or SDC trains shall be Operable
with at least one in operation. Mode 5 requires one SDC train
Operable and in operation and a second train Operable or the RCS
loops filled and at least one SG with >10% level.
In Mode 5 one Operable SDC train requires a facility consistent SDC
pump and heat exchanger with cooling water provided from an
RBCCW pump and a SW pump both powered from the same facility
as the SDC pump and piping capable of delivering the cooling water.
Administratively this allows using a Z1 pump and Z2 piping or vice-
versa for providing SW or RB cooling flow.
In Mode 5 when two Operable SDC trains are required, facility consistency is required for everything except a single SW header
may provide the cooling water flow path to 2 RBCCW heat
exchangers, 2 SW pumps, (Z1 & Z2), are required.
- 2002-632 In Mode 6, there is a refueling Technical Specification that specifies when one or two loops of SDC are required to be operable. At all
reactor water levels, at least one loop of SDC must be operating to
ensure: That sufficient cooling capacity is available to remove decay heat and maintain the water in the vessel below 140° F.
Sufficient coolant circulation is maintained through the reactor core to minimize the effects of a boron dilution incident and
prevent boron stratification.
Boron dilution analysis assumptions are met.
The requirement to have two shutdown cooling loops operable when
the refueling pool is unavailable as a heat sink ensures that a single
failure of the operating SDC loop will not result in a complete loss of
decay heat removal capability.
Tech Spec bases define what is required to constitute an Operable
SDC train. In Mode 4, an Operable SDC train requires an SDC pump, SDC Hx, RBCCW header, RBCCW pump, SW header, and SW
pump all from the same facility, as well as the manual valves needed
to properly align the systems. Mode 5 and 6 are different in that a
single SDC train can be Operable supplied from either SW header.
This is possible due to the redundancy inherent in the SW headers and valving with respect to the RBCCW HXs.
Lesson Title: Shutdown Cooling System Page 44 of 82 Revision: 4 ID Number: SDC-00-C G. MALFUNCTIONS AND FAILURES
- 2. Core Boiling with RCS Vent Path or Nozzle Dams Installed If the reactor vessel head is installed and, concurrently, a large vent path exists at the Reactor Coolant Pump (RCP) (such as
during an RCP seal replacement), a significant potential problem exists. This is due to the location at which the Shutdown Cooling System returns to the Reactor Coolant System. Under these
conditions, during a Loss of Shutdown Cooling, steam formation in
the core region may cause level to be suppressed within the reactor vessel. Level in the vessel would decrease as water is forced out of the RCP. This would continue until steam could be
vented through the open suction of the RCP. In order for a steam
vent path to be established, level must decrease to 57 inches
below the hot leg centerline. Only then can steam begin to flow
through the SG tubes, down through the open RCP suction leg, and out of the disassembled RCP. It must be noted that the active
fuel is only 10 inches below the top of the open RCP suction leg.
Figure 2
Figure 21 The core can be further jeopardized while the RV head is installed, if the hot leg nozzle dams are also installed. Any failure of the
Shutdown Cooling System that permits core boiling could result in
depression of the water level in the core to below the bottom of the Core Support Barrel. Under this condition, if prompt action is not
taken to prevent the onset of boiling, there is no operation that may
be performed that would prevent core melt from occurring.
Figure 22 Because of the potential problems that these situations present, a vent path from the RCS hot legs is required to be provided anytime
the plant is placed in a "reduced inventory" condition while
Shutdown Cooling is in operation. To ensure an adequate vent
path is present for the steam that might be generated during a Loss
of Shutdown Cooling, the Pressurizer manway is normally removed prior to entering a "reduced inventory" condition. This ensures that these situations cannot develop and present a challenge to core cooling. 3. Failures leading to a Loss of Shutdown Cooling Loss of shutdown cooling has been most commonly initiated by the accidental closure of a SDC suction valve, low reactor vessel level
resulting in a loss of LPSI pump suction, or an inadvertent trip of the
running LPSI pump.
An electrical trip of the LPSI pump motor supply breaker may be
caused by either an overcurrent condition on the LPSI pump motor or a ground fault on the load side of the supply breaker. The
overcurrent trip on this breaker is set at approximately 100 amps.
Lesson Title: Shutdown Cooling System Page 45 of 82 Revision: 4 ID Number: SDC-00-C The LPSI pump will also trip if a Sump Recirculation Actuation Signal (SRAS) is received from the Engineered Safeguards Actuation
System (ESAS). This signal is normally blocked during Shutdown
Cooling System operation. Blocking of this signal is accomplished by
bypassing all four SRAS channels on the Emergency Safeguards
Actuation System (ESAS) cabinets.
A pump motor trip will also occur if the motor is running and a Loss of
Normal Power (LNP) occurs. This "Load-shed" trip, generated from
the "Fast transfer circuit" associated with the transfer from the Normal
Station Services transformer to the Reserve Station Services
Transformer, locks out the LPSI pump breaker in preparation for
energizing the 24C and 24D 4160 VAC electrical buses from the
Emergency Diesel Generators (EDG). This trip is disabled prior to initiating Shutdown Cooling System operation by opening fingers in the 94TG-1 and 94TG-2 test circuits (OP 2310). The test circuits are
located on the rear of C08. This operation minimizes spurious LPSI
pump trips that might occur while the plant is shutdown. These
spurious "Load-shed" trips could occur as the result of either Main
Turbine control system testing or breaker operations in the
switchyard. If a "Load-shed" trip does occur, the operator must reset
the pump breaker, by placing the handswitch to "STOP" after power
has been restored, prior to restarting the pump.
When Shutdown Cooling is required to be in operation, a loss of power to either bus 24C or 24D would require operator action to
restore core cooling. After the associated electrical bus has been re-
energized by the Emergency Diesel Generator (EDG), the effected
LPSI pump will not automatically restart. This is due to the fact that a
Safety Injection Actuation Signal (SIAS) Block is present and the
Engineered Safeguards Actuation System (ESAS) has not generated an auto start signal (i.e. SIAS). Therefore the operator must manually restart the associated LPSI pump in accordance with the guidance
contained in the Abnormal Operating Procedure (AOP 2572).
RO-11A A complete loss of power to the 'A' Train components would involve a loss of the following buses: 24C, 22E, and VR-11. If the buses are not
re-energize the following SDC components are affected:
RO-11B A LPSI Pump LPSI Injection Valves SI-615 and 625 Loss of power to following instrumentation T351X, T351Y, and TR351 - SDC temperatures and recorder F6043 and T6051 - SDC HX A RBCCW flow and temperature F3023 and T303X - SDC HX A SDC flow and temperature
Lesson Title: Shutdown Cooling System Page 46 of 82 Revision: 4 ID Number: SDC-00-C F312 and F322 - LPSI flow to Loop 1A and 1B A complete loss of power to the 'B' Train components would involve a loss of the following buses: 24D, 22F, and VR-21. If the buses are not
re-energize the following SDC components are affected:
B LPSI Pump LPSI Injection Valves SI-635 and 645 Loss of power to following instrumentation F6042 and T6056 - SDC HX B RBCCW flow and temperature F3024 and T303Y - SDC HX B SDC flow and temperature F332 and F342 - LPSI flow to Loop 2A and 2B A loss of RBCCW cooling flow to the SDC HXs could be caused by a
loss of power to the RBCCW components or a loss of RBCCW
system integrity. Any malfunction associated with the RBCCW system
will have a corresponding effect on the associated SDC system trains ability to cool the core. A loss of RBCCW flow through the SDC HX
would require shifting to the opposite SDC system train or re-
establishing the affected RBCCW system.
RO-11C A loss of Instrument Air will cause a loss of control of the two SDC flow control valves, SI-657 and SI-306. The SDC HX Flow Control
Valve, SI-657, will fail close resulting in a loss of cooling flow from the SDC HXs. The SDC Total Flow Control Valve, SI-306, will fail open
maintaining SDC flow through the system and RCS. Both valves have
the capability of local manual control. Prolonged operation without
instrument air will require taking local control of the valves and adjusting flow using manual handwheel control.
RO-11D A prolonged loss of SDC can occur when the RCS is in a reduced inventory condition (i.e. drained below the top of the hot leg). Events
involving a loss of SDC capability with reduced reactor vessel water
level have occurred rather frequently. More than 10 events involving
the loss of SDC capability for greater than one hour occurred between
mid 1985 and mid 1988. Three of these events resulted in boiling in
the reactor core.
With reduced vessel water level, there is an increased probability that
a vortex may form within the RCS in the vicinity of the SDC suction
line. Vortexing is most likely to occur if high SDC flow rates and low
level at the hot leg suction co-exist. The formation of a vortex can
result in voiding and air binding of the SDC suction line. The
arrangement of the suction line piping is such that a loop seal is
formed between the RCS and LPSI pumps. Thus, this piping configuration can prevent the suction line from reflooding once it has Figure 3 Lesson Title: Shutdown Cooling System Page 47 of 82 Revision: 4 ID Number: SDC-00-C been voided. In the event that the suction line has been voided, priming of the LPSI pump suction line can be accomplished by either: 1. Raising RCS hot leg level with a charging pump (which has been aligned to take a suction on the RWST) in order to flood
the LPSI pump suction.
- 2. Flooding the pump suction directly from the RWST.
If the line remains air bound, it can be evacuated using the vacuum
priming sub-system. This sub-syst em is connected to the Shutdown Cooling System suction line high point vent inside the Containment
Building.
It is also possible, when in a reduced RCS inventory condition, to
pressurize the RCS cold leg with air. This occurs when air bubbles
are entrained within the coolant at the SDC suction as the result of
minor vortexing. These air bubbles are carried through the Shutdown
Cooling System and come out of solution in the piping on the RCP
discharge legs. These bubbles can cause a small pressure buildup in
this region of the RCS. A pressure build-up in this piping, in turn, causes level at the steam generator to rise and level in the RCS cold leg, within the RCP discharge piping, to drop. This outcome is the
result of the physical arrangement of the piping that results in the
creation of a manometer within the Reactor Coolant System.
Because of this, level measurements taken at the Steam Generator
may not be a valid indication of actual level in the vicinity of the SDC
suction line. This effect on the level indication has misled operators
into inadvertently draining the RCS, with an ensuing loss of suction
pressure at the SDC pumps.
Figure 2 The most frequent type of decay heat removal incident is a loss of flow due to an inadvertent, automatic SDC suction valve closure.
Automatic suction valve closure events have resulted in loss of
Shutdown Cooling System flow more frequently than any other failure mode. A loss or malfunction of the SDC system will adversely affect the
systems it was designed to support. If SDC is not available to cool the
RCS then an alternate means of RCS cooling will need to be
established. If the plant is in Operational Mode 5, then a RCS Loop
and its SG and RCP can be used for core cooling. If the plant is in
Operational Mode 6 and one SDC loop is not available than
conditions must be established to ensure there is sufficient capability of flooding the reactor vessel/refueling cavity with borated water.
RO-12A If the ability to cool the core is lost because of a causality to the SDC system then actions are taken to protect personnel and the public
from core boiling. Any refueling activities and maintenance activities in
containment will be stopped and actions will be taken to establish
Containment Closure prior to the most limiting of the following:
RO-12B Lesson Title: Shutdown Cooling System Page 48 of 82 Revision: 4 ID Number: SDC-00-C RCS boiling 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> from loss of SDC If there is available level in the RWST, it can be used to gravity feed makeup to the RCS when SDC can not be made available i.e., a loss
of all AC. This method uses the SDC system alignment into the RCS
and requires the LPSI pump suctions from the RWST to be throttled
open. The use of this gravity flow makeup path is time sensitive due
to RCS heatup and possible pressurization.
RO-12C If the SDC system is being used to supplement the SFPC system, then alternate methods to keep the spent fuel pool cooled will need to
be implemented. These methods include re-establish SFP cooling or
initiate feed and bleed cooling from either the RWST, or Primary
Makeup Water system, or Au xiliary Feedwater system.
RO-12D H. OPERATING EXPERIENCES
- 2. Introduction These events take place during cold shutdown conditions while the
Shutdown Cooling System is in operation to remove decay heat.
Shutdown cooling events which occur in Mode 5 or 6 are often
initiated or complicated by changing plant conditions and by
concurrent maintenance operations. Reduced decay heat levels
present during these events usually permit more time to respond than
is generally available during power operation. However, fewer protective features are operative in these lower modes. This results in a much greater reliance on operator action for prevention or
termination of these events.
According to a report by the Office of Analysis and Evaluation of Operational Data (AEOD/C503), 130 events related to decay heat
removal malfunctions were reported between 1976 and 1981 These
events occurred during approximately 500 reactor years of operation.
This equates to 0.25 events per reactor year or, to put it differently, 1
event approximately every 4 year
- s. Although none of the 130 events analyzed by the AEOD report resulted in core uncovery, the Office concluded that these events should be considered "Significant Precursors" to more serious incidents.
Until 1983, virtually all risk assessment studies (including the Final Safety Analysis Report) looked at decay heat removal system failures
from the standpoint of an accident initiated from power operation. In
other words, the analyses were directed towards the inability to
achieve shutdown cooling entry conditions rather than what would
happen if the shutdown cooling system malfunctions after initiation.
In 1983 the Nuclear Safety Analysis Center (NSAC) reviewed
approximately 100 decay heat removal incidents looking for root
Lesson Title: Shutdown Cooling System Page 49 of 82 Revision: 4 ID Number: SDC-00-C causes and published a report (NSAC-52) stating their findings and recommendations. In 1985, NSAC performed a probabilistic risk
assessment of the Zion Station's decay heat removal systems and
procedures to investigate the likelihood of fuel damage as a result of
decay heat removal incidents (NSAC-84).
Of particular interest is that the AEOD study and both NSAC studies
concluded that "major hardware improvements would have had little effect in preventing or mitigating the outcome (of the event)"
(NSAC-52). On the other hand, all three studies cited human factors:
operating and maintenance procedures, administrative controls, and
personnel error as the significant factors in most of the decay heat
removal incidents studied. It should also be noted that loss of shut down cooling events have continued to occur. SOER 85-4 and SOER 88-3 document 74 additional events that occurred between the time of
the NSAC--52 study and May of 1988, a seven year period. These
SOERs support and amplify the findings of the NSAC studies.
After evaluating 96 shutdown cooling events that occurred between 1976 and 1981, NSAC-52 concluded that there are three main safety
concerns involved with these types of incidents. These concerns are
- 1) loss of coolant inventory, 2) loss of decay heat removal capability, and 3) inadvertent pressurization (cold over pressure). Many incidents
involve one or more of these safety concerns.
- 3. Loss of Coolant Inventory The probability for a loss of coolant inventory event may actually be
increased during shutdown periods because large normally isolated
systems, such as the Shutdown Cooling System, are connected to the Reactor Coolant System. NSAC-52's analysis of one cold
shutdown LOCA, which was accompanied by a degradation of safety
injection capability, demonstrated a potential for the core being
uncovered. If it had occurred at the higher temperatures and higher decay heat levels seen immediately after entry into shutdown cooling, the operators would have had approximately 25 minutes to take
corrective actions before the core would have begun to uncover.
Ten of the events analyzed in NSAC-52 demonstrated various scenarios for losing RCS inventory via the Shutdown Cooling System.
Every loss of inventory occurring during SDC operation resulted from
a fluid loss path within the boundaries of the Shutdown Cooling system (none have resulted from breach in the RCS itself).
Furthermore, nine of the ten events resulted from maintenance
actions or valve alignments (automatic or manual) in which no
physical breach of Shutdown Cooling System pressure boundary
occurred. The only failure of a pressure boundary that occurred (a
gross packing leak on a SDC valve) was compounded by fluid
contraction within the RCS. The following occurrences at plants have resulted in a loss of coolant inventory which in turn caused a loss of
Lesson Title: Shutdown Cooling System Page 50 of 82 Revision: 4 ID Number: SDC-00-C shutdown cooling: Inadvertent containment spray, with flow supplied by the SDC system, as the result of unintentional manual actions (including St. Lucie, a CE plant, on November 3, l978).
Inadvertent loss of inventory via the SDC suction relief valve (resulting in a loss of SDC due to leak isolation).
Inadvertent loss of inventory due to miss-positioned cross-connect or drain valves.
SDC valve packing gland removal during plant pressurization, dislodging the valve packing and gland.
Gross packing leakage resulting in a rapid cool down using SDC in order to effect repairs. The rapid cool down caused fluid
contraction in the RCS, contributing to the event.
Another loss of coolant inventory event was an accidental loss of inventory to the Containment Building sump as the result of an
inadvertent SRAS.
SOER 85-4 points out that isolation of Shutdown Cooling would
have stopped the inventory loss in each of the 10 events outlined
in the NSAC 52 report.
- 4. Loss of Decay Heat Removal Capability The loss of decay heat removal capability can be the result of a loss
of flow within the Shutdown Cooling System or the loss of a heat sink
for the Shutdown Cooling System. Events occurring shortly after SDC
entry leave the operator little time to respond before bulk boiling
conditions are reached. Heat-ups of over 100° F in less than 20
minutes have occurred in plants that had been partially drained for
maintenance.
Two major types of loss of flow events can occur which can induce a
loss of decay heat removal capability for an extended period of time.
Loss of flow due to an inadvertent, automatic SDC suction valve closure. This is the most frequent type of decay heat removal
incident. Twenty-seven separate automatic suction valve closure
events resulted in loss of Shutdow n Cooling System flow over the five year period of the NSAC study. SOER 85-4 documents
an additional 21 events caused by inadvertent, automatic SDC
suction valve closure in the three years immediately following the NSAC study.
Loss of Shutdown Cooling System flow caused by reactor vessel level indication errors during intentional RCS inventory reductions. Evolutions requiring RCS drain-down to mid loop
often place the water level very close to the point at which
Lesson Title: Shutdown Cooling System Page 51 of 82 Revision: 4 ID Number: SDC-00-C vortexing at the SDC pump suction will develop. This in turn can lead to air binding or cavitation of the SDC pumps. Higher flow
rates and higher fluid temperatures increase the possibility of air
entrainment and/or pump cavitation. Twelve of the 96 events
analyzed by NSAC-52 were the result of erroneous level
indication. In the three years immediately following the NSAC
study, SOER 85-4 documents an additional 20 events during intentional RCS inventory reduction. Other loss of decay heat removal events include: Loss of flow or degraded cooling due to other valve closures.
Although this occurs with moderate frequency, system redundancy helps to mitigate the consequences of this event.
Degraded cooling as the result of a loss of heat sink. The heat sink for the Shutdown Cooling System performs safety related
tasks while in "Hot" modes, and therefore is a system with which
most operators are fairly familiar. It is also quite reliable. Most
events involving a loss of heat sink occur when maintenance on
the system has reduced its redundant capabilities.
Loss of flow due to the loss of the running SDC pump. This event occurs quite frequently (14 times during the NSAC-52 study), but
is fairly minor owing to the ability to run the alternate SDC pump.
Note that in this case "Loss" refers to an electrical or mechanical
failure, not cavitation or air binding, which tends to affect both
pumps. In the three years immediately following the NSAC study, SOER 85-4 documents an additional 13 events caused by loss of the running LPSI pump.
Inadvertent loss of flow due to automatic SRAS. Although highly unlikely (due to administrative controls), it is possible for this event to occur at MP 2. The LPSI pumps would trip, but the stop signal
could be overridden. The containment sump suction valves would
open, but three check valves should prevent loss of inventory
from the RCS to the containment sump via the SDC suction.
Inability to establish SDC flow as a result of the failure of the SDC suction valves in the closed position. Although this event occurs
with moderate frequency, it usually occurs during initial attempts
to enter SDC (five of six events analyzed by NSAC-52). This
typically delays plant cool-down and raises some concern about
the ability to obtain cold shutdown conditions. However, the plant
is still capable of being cooled by the steam generators at this point, so the probability of core damage is low.
RCS void formation during SDC operation interfere with the ability to operate the Shutdown Cooling System. However, during cold
shutdown conditions, it is difficult to form a steam void. Four plants
have experienced voids while on shutdown cooling. Three of these
Lesson Title: Shutdown Cooling System Page 52 of 82 Revision: 4 ID Number: SDC-00-C were caused by rapid cool-down and depressurization. The other event was a Reactor Vessel head bubble that developed when RCS
temperature was below 200° F. An improper valve lineup, while
draining the RCS, resulted in sufficient vacuum being drawn within
the RCS for water at approximately 150° F to flash to steam. 5. Cold Over Pressure Events Cold over pressurization (COP) is the third safety concern associated
with decay heat removal incidents. In cold over pressure events, the
primary concern is not core damage but exceeding the reactor vessel
brittle fracture prevention limit. Unless the cold over
pressure causes a catastrophic failure of the reactor vessel, core damage is far from likely. Cold over pressurization is not the same as pressurized thermal shock because for COP, no thermal gradient, and hence no thermal stress, is present in the reactor vessel wall.
Only the pressure stress and fracture toughness of the reactor vessel
are of concern.
The condition most likely to lead to cold over pressurization is operation with the primary plant water solid. As in loss of inventory
and loss of heat removal events, the most significant factor
contributing to the events has been the performance of maintenance
and/or testing activities. Analyzing or predicting the occurrence of a
cold over pressure event is more difficult than other decay heat
removal safety concerns, because usually a combination of events must occur to cause the over-pressure condition; however, these combinations can and have occurred. One PWR event, which
occurred during cold shutdown with a solid Pressurizer, resulted in
pressurization to 1100 psig. The potential existed to pressurize all the
way to primary safety setpoints without automatic protective action.
Cold over pressurization may be more likely due to reliance on power operated relief valves (PORVs) which have had their setpoints
lowered, thus introducing the possibility of calibration error or detector
malfunction.
Operation of HPSI pumps during cold shutdown conditions can result
in over-pressurization. Other plants have experienced problems as a
result of inadvertent SIAS actuation during low temperature, low
pressure conditions. Administrative controls limit the number of HPSI
pumps during shutdown cooling and solid plant operations in an
attempt to avoid this concern.
Additionally, the HPSI pumps are equipped with a Pull-to-Lock feature on the handswitches which will be used to protect SDC
from an overpressure condition by preventing an inadvertent start when the RCS is >190F and an available HPSI is required.
Lesson Title: Shutdown Cooling System Page 53 of 82 Revision: 4 ID Number: SDC-00-C 6. Conditions Affecting the Severity of a Shutdown Cooling Incident Given that the main purpose for cold shutdown operations is to perform maintenance/testing on equipment that cannot be taken out
of service while in "hot" conditions, it must be assumed that
equipment conditions and availability will be degraded from normal
conditions. Thus, the limiting factor as to which equipment is removed
from service and when, is the operational mode of the plant.
NSAC-84 uses a set of six procedure related sequence of event "trees" to describe the various activities normally associated with cold
shutdown outages:
Plant Shutdown Takes the plant from hot shutdown, using the steam generators
and AFW, to cold shutdown with decay heat removal by SDC.
The RCS is placed in one of two conditions.
- 1. Bubble (N 2 or steam) in the Pressurizer 2. Solid plant conditions Draining for refueling or maintenance Takes the plant from a solid condition to a drained condition with
system level being maintained at the RCS mid loop elevation.
Filling for refueling The reactor vessel head is removed and system level raised to
refueling level in the refueling cavity.
Draining the refueling cavity after refueling The refueling cavity is drained and the Reactor Vessel head is
replaced.
Refilling the RCS after refueling or maintenance Takes the plant from a drained condition to a solid condition. Cold Start-up Takes the plant from a cold, solid condition to a hot shutdown
condition with SDC secured.
It is possible to have an event that could affect any or all of the three
safety concerns during any of these event trees. However, some
events are more likely to occur at certain times. Also, some events
are more likely to lead to core damage if certain plant conditions exist.
Listed below are the six sequence of event trees and the safety
concern(s) most likely to be affected by events that could occur.
Lesson Title: Shutdown Cooling System Page 54 of 82 Revision: 4 ID Number: SDC-00-C Plant Shutdown All three safety concerns can be significantly impacted by any SDC event during this evolution. NSAC-52 recommends during plant cool-down when shutdown cooling is first initiated high RCS
temperatures, pressures and decay heat levels demonstrate the
potential for more severe losses of inventory or loss of decay
heat removal capability. It is therefore prudent to exclude all but emergency evolutions for this short time period of hot shutdown (shutdown cooling) operation.
Draining for Refueling or Maintenance During this evolution, shutdown cooling has been placed in service and is operating. Most plants limit maintenance on SDC
during this period of time, so the likelihood of a LOCA through
valve miss-operation or mistaken loosening/disassembly of
fittings is small. (Random pipe break LOCAs could occur at any
time). The draining process has left room for fluid expansion, so
cold over pressure conditions are unlikely. Loss of heat removal is the prime concern since decay heat levels tend to still be significant. RCS volume is diminished, so there is less room for
heat absorption and, most importantly, loss of suction head or air
entrainment to the SDC pumps becomes much more likely.
NSAC-52 recommends:
- 1. Tight administrative controls over evolutions that remove coolant inventory.
- 2. Frequent visual checks of local standpipe level and comparison to other level indications.
- 3. Continuous trend analysis of Reactor Vessel water level changes. 4. In addition, the study recommends that both SDC trains should be continuously available in Mode 4 and during the first few days of Mode 5 operation. Technical Specifications
additionally require that at least one heat removal loop/train
be continuously in service.
Filling for refueling This appears to be the safest mode of operation for shutdown
cooling. Cold over pressure is impossible due to removal of the
Reactor Vessel head. Loss of heat removal is less of a concern
due to the large volume of water available for boil-off. Loss of
inventory is less of a concern because:
Lesson Title: Shutdown Cooling System Page 55 of 82 Revision: 4 ID Number: SDC-00-C 1. Low system pressures minimize leakage flow rates.
- 2. Large quantities of water in the refueling cavity provide the operators with more time to respond.
Draining the cavity after refilling Risk is low during this evolution as well. However, two potential concerns do exist, both of which are associated with loss of
inventory. They are:
- 1. Loss of inventory is harder to recognize due to the large amount of water being transferred. Operators should ensure
all inventory is accounted for.
- 2. Over draining could result in inadequate shielding and possibly inadvertent core uncovery. Possible exposure
hazards to personnel in containment.
Refilling the RCS after refueling or maintenance Loss of inventory concerns are minimal due to the fact that
systems are already lined up to provide makeup to the RCS.
Loss of heat removal is less of a concern due to the lower decay
heat levels. Cold over-pressure events present the greatest
hazard. Inattentiveness, or inaccurate level indication can lead to
unanticipated over-pressurization.
Cold Start-up Loss of inventory and cold over-pressure are the primary
concerns due to the increased energy content of the RCS fluid.
In addition, valve manipulations during the removal of shutdown cooling present the possibility of inadvertently releasing RCS
water. Again concern over loss of heat removal is less because:
- 1. Lower decay heat levels exist. 2. The steam generators are usually available as a heat sink.
- 7. Conclusion The NSAC studies and SOER 88-3 conclude that cold shutdown periods present significant challenges to the safe operation of a
nuclear power plant. Fewer protective features combined with
changing plant status due to maintenance and testing evolutions
cause a much greater reliance on operator action for prevention or
termination of events occurring during cold shutdown. Analyses have
identified the loss of SDC as a significant contributor to the potential for core damage. In several events after the period of the NSAC study, the temperature of an open RCS has approached the boiling
point during the loss of SDC capability (SOER 85-4). The probability
of uncovering the core by the loss of inventory due to boiling is greatly
Lesson Title: Shutdown Cooling System Page 56 of 82 Revision: 4 ID Number: SDC-00-C increased upon the loss of SDC.
Given the inevitability of cold shutdown operation, the operator should be aware of the type of shutdown cooling events most likely to occur
during a given plant condition. Operators should also be aware of how
to respond to possible shutdown cooling events. NSAC-52 concludes
that increased awareness by Control Room Operators of
maintenance and testing in progress, increased awareness of plant
status by maintenance personnel, and improved communications systems and usage formality, can all contribute to improved shutdown reactor safety.
The probability of a shutdown cooling event occurring is high (0.25 events per reactor year) and while certain changes to administrative
controls help lower the probability, it cannot be eliminated. This review
has noted a number of instances where inadvertent mode changes
and bulk boiling in the core have occurred. Core uncovery is possible
in as little as 30 minutes in some circumstances.
In all the reports reviewed, there was a striking similarity in their
conclusion. Some minor hardware changes might improve plant
safety during cold shutdown operations but major improvements
would have had little effect in preventing or mitigating the SDC events
studies. Procedures and correct operator response are the key to
safe shutdown cooling operation.
- 8. SER 12-86 High Cooldown Rate Due To Inaccurate Closed Position Indication On Motor-Operated Valves During a plant cooldown, the cooldown rate exceeded the technical
specification limits when the Shutdown Cooling System (SDCS)
was aligned to the Reactor Coolant System (RCS). The high
cooldown rate occurred because the SDCS heat exchangers were
not completely isolated from the system. The heat exchanger
isolation valves indicated closed in the control room but were
actually partially open. The inaccurate closed position indication on these valves resulted from changes made to their motor operator limit switch settings. The limit switch setting changes were made to
modify the motor operators' torque bypass set points, but also
affected the closed position indication that comes from the same
limit switch assembly.
This event is significant because it demonstrates how changing motor-operator limit switch settings to resolve one problem, i.e.,
inappropriate torque switch bypass settings, can lead to another
problem, i.e., motor-operated valves indicating closed when they
are actually partially open.
- 9. SER 19-91 Loss Of Decay Heat Removal Capability Due To Inappropriate Maintenance And Testing
Lesson Title: Shutdown Cooling System Page 57 of 82 Revision: 4 ID Number: SDC-00-C During a refueling outage, reactor vessel water level was inadvertently drained to the bottom of the Reactor Coolant System
hot legs during post-maintenance testing of a decay heat removal
pump suction isolation valve. Decay heat removal was lost and
radiation levels above the reactor vessel increased from less than
80 mrem/hour to 8,000 mrem/hour.
At another station during a refueling outage, maintenance on a
check valve caused an interruption of decay heat removal
capability by admitting air into the system and air binding the
shutdown cooling pump.
These events are significant because incorrect performance and
scheduling of maintenance and testing resulted in a loss of decay
heat removal capability.
- 10. Review of Loss of Shutdown Coolant Events 01/2004 INPO Topical Report
TR4-33 1) Key Concepts a) After years of improvement, rates have increased. A fivefold increase in 2003 as compared to 2002 b) Major contributor was lack of self-checking.
Of the 34 events, 25 occurred on BWRs Three-fourths of the events were due to human performance, including all five events in 2005.
10 due to Inadequate Self Checking 8 due to Inadequate Procedures c) Categories of events causes.
12 of 34 while placing SDC in service.
9 of the 12 were PWRs this 9 to 12 ratio is the same as the ratio of BWRs to PWRs in the country, 34 to 69 respectively.
8 due to Testing.
6 due to Maintenance.
4 while restoring or swapping systems
Lesson Title: Shutdown Cooling System Page 58 of 82 Revision: 4 ID Number: SDC-00-C 3 due to Tagging.
4 due to Other causes.
10 due to lack of Self Checking 8 due to Inadequate Procedures d) Causal analysis There was not enough information to determine why the rise in Loss of SDC is occurring, or why BWRs are having more problems.
4 events resulted in > 10 F rise in Temp.
UE/D1 EU1 -Uncontrolled RCS Temp increase >
10 F. 11. Review of CR-04-06166 Reportability evaluation for gas binding of
RHR Pumps on Millstone Unit #3. Review with trainees the basic
causal factors for the Unit #3 event.
CR-04-06166
Lesson Title: Shutdown Cooling System Page 59 of 82 Revision: 4 ID Number: SDC-00-C I. TABLES 2. Component Design Data Table Component Design Data
- 1. LOW PRESSURE SAFETY INJECTION PUMPS Quantity Type Manufacturer Basic Material Pumped Fluid
Temperature of pumped fluids Motor Voltage
Power Supply
A:
B:
Horsepower Acceleration time; at rated voltage
Design maximum suction pressure
Design Pressure
Design Temperature
Design Flow (excluding min. flow)
Minimum flow
Maximum flow
- 1. Head at maximum flow Design head
Shutoff head
NPSH required at 3000 gpm
NPSH available minimum
Seals Seal Cooling 2 Single stage, Vertical, Centrifugal
Ingersoll-Rand ASTM A351 GR CR8M Borated Water
40 to 300° F 4160 VAC
24C (A-309)
24D (A-404)
400 BHP 4 sec. 300 psig 500 psig 350° F 3000 gpm 100 gpm 4500 gpm 121 PSID 154 PSID 185 PSID 13 ft.
25 ft.
Mechanical
RBCCW 2. RWST Manufacturer Richmond Engineering Company Lesson Title: Shutdown Cooling System Page 60 of 82 Revision: 4 ID Number: SDC-00-C 2. Component Design Data Table Component Design Data Design Pressure Atmospheric Design Temperature 120° F Net Capacity 475,000 gallons 3. Shutdown Cooling Heat Exchangers Manufacturer Engineering & Fabricators, Inc.
Quantity 2 Type Shell & Tube Codes ASME Section III, Class C, 1968 Edition through Summer 1969 Addendum Tube Side: Fluid Design Flow, gpm Design Pressure Design Temperature
Pressure drop (at 1.5 x 10 6 lb/hr) Materials
Reactor Coolant (1% Boric Acid)
3400 gpm 500 psig 400° F 10 PSID Austenitic Stainless Steel Shell Side
- Fluid Design Flow Design Pressure Design Temperature
Pressure drop (at 2.41 x 10 6 lb/hr) Material Heat Load Service Transfer Rate Reactor Building Closed Cooling Water
5400 gpm 150 psig 250° F 10 PSID Carbon Steel
27.2 million Btu/hr 256 Btu/hr - °F - ft.
2 Lesson Title: Shutdown Cooling System Page 61 of 82 Revision: 4 ID Number: SDC-00-C 2. Component Design Data Table Component Design Data
- 4. Miscellaneous Components Valves: 2-1/2 in. and larger 2 in. and smaller Standard
Seismic Piping: Material 2-1/2 in. and larger 2 in. and smaller Fittings: 2-1/2 in. and larger 2 in. and smaller Butt-welded, ANSI 1500 lb. rating, stainless steel Socket-welded, ANSI 600 lb. rating, stainless steel Draft ASME Code for pumps and valves for Nuclear Power Class 2, 1968 Class 1
ASTM A-312, Type 304 Sch 10S Sch 40S Butt-welded except at flange Socket-welded Lesson Title: Shutdown Cooling System Page 62 of 82 Revision: 4 ID Number: SDC-00-C
- 3. Power Supply Summary Table Component Main Power Alternate Power Control Power LPSI A (P-42A) 24C DV10 LPSI B (P-42B) 24D DV20 SDC Suction Isolation 2-SI-652 MCC B61 SDC Suction Isolation
2-SI-651 MCC B51 Lesson Title: Shutdown Cooling System Page 63 of 82 Revision: 4 ID Number: SDC-00-C
- 4. Alarm Summary Table Alarm Title Module Source Instrument Setpoint LPSI Pump A Overload/Trip C-01 A-2 51X relay 3 relay overcurrent ground fault LPSI Pump B Overload/Trip C-01 B-2 51X relay 3 relay overcurrent ground fault Engineered Safeguards Room A
Temp Hi C-01 A-7 TS-8052 110° F Engineered
Safeguards Room B
Temp Hi C-01 B-7 TS-8053 110° F LPSI Pump A Suction
Pressure Lo C-01 A-8 PT 3051 13.5 psig LPSI Pump B Suction
Pressure Lo C-01 B-8 PT 3053 13.5 psig LPSI Pump A Motor
Current Hi/Lo C-01 C-8 I 3700A Hi: 50 amps Lo: 20 amps LPSI Pump B Motor
Current Hi/Lo C-01 D-8 I 3700A Hi: 50 amps Lo: 20 amps SI-651 Open C-01 C-9 P-103-1 ZS-651 > 280 psia and 2-SI-651 open SI-652 Open C-01 D-9 P-103 ZS-652 > 280 psia and 2-SI-652 open SI-652 Opening Coil Energized C-01 C-39 42-0 relay SI-652 Manual Disc
Closed C-01 D-39 89-SI-652 Loop 1A Low Press
SI flow Computer F-312 Lo: 0.0 gpm Hi: 1800 gpm Loop 1B Low Press
SI flow Computer F-322 Lo: 0.0 gpm Hi: 1800 gpm Lesson Title: Shutdown Cooling System Page 64 of 82 Revision: 4 ID Number: SDC-00-C 4. Alarm Summary Table Alarm Title Module Source Instrument Setpoint Loop 2A Low Press SI flow Computer F-332 Lo: 0.0 gpm Hi: 1800 gpm Loop 2B Low Press
SI flow Computer F-342 Lo: 0.0 gpm Hi: 1800 gpm LPSI Pump A Disch
Press Computer P302-X Lo: 0.0 psig Hi: 450 psig LPSI Pump B Disch
Press Computer P302-Y Lo: 0.0 psig Hi: 450 psig
Lesson Title: Shutdown Cooling System Page 65 of 82 Revision: 4 ID Number: SDC-00-C
- 5. Instrument Summary Table Noun Name Tag Readout Location Range Uses Normal Reading Low Pressure Safety Injection Flow to Loop 1A Cold Leg FI-312 C-01 1500 gpm Low Pressure Safety Injection Flow to
Loop 1B Cold Leg FI-322 C-01 1500 gpm Low Pressure Safety Injection Flow to
Loop 2A Cold Leg FI-332 C-01 1500 gpm Low Pressure Safety Injection Flow to
Loop 2B Cold Leg FI-342 C-01 1500 gpm Total Shutdown Cooling System Flow FIC-306 C-01 7000 gpm "A" LPSI Pump Discharge Pressure PI- 302X C-01 200 psig "B" LPSI Pump Discharge Pressure PI-302Y C-01 200 psig "A" LPSI Pump Suction Pressure PI-3051 Local 40 to 265 psig "B" LPSI Pump Suction Pressure PI-3053 Local 40 to 265 psig Shutdown Cooling System Return
Temperature to RCS TR-351Y C-01 65° F to 300° F Shutdown Cooling System Suction
Temperature TR-351X C-01 65° F to 300° F "A" SDC Heat Exchanger Inlet
Temperature TI-3025 Local 65° F to 300° F "B" SDC Heat Exchanger Inlet
Temperature TI-3026 Local 65° F to 300° F "A" SDC Heat Exchanger Outlet
Temperature TI-303X C-01 80° F to 120° F "B" SDC Heat Exchanger Outlet
Temperature TI-303Y C-01 80° F to 120° F Position indication for 2-SI-306 (SDC
System Flow Control Valve)
TI-3025 C-01 Open Position indication for 2-SI-440 (LPSI
Pump Suction Cross-connection)
ZS-440 C-01 Open Lesson Title: Shutdown Cooling System Page 66 of 82 Revision: 4 ID Number: SDC-00-C 5. Instrument Summary Table Noun Name Tag Readout Location Range Uses Normal Reading Position indication for 2-SI-441 (LPSI Pump Suction Cross-connection)
ZS-441 C-01 Open Position indication for 2-SI-651 (SDC
Suction Line Isolation Valve)
ZS-651 C-01 Open Position indication for 2-SI-652 (SDC
Suction Line Isolation Valve)
ZS-652 C-01 Open Position indication for 2-SI-657 (SDC
Heat Exchanger Flow Control Valve)
ZS-657 C-01 Throttled Position indication for 2-SI-659 (ECCS
Pump Minimum Flow Recirculation
Isolation)
ZS-659 C-01 Open Position indication for 2-SI-660 (ECCS
Pump Minimum Flow Isolation)
ZS-660 C-01 Open Position indication for 2-SI-615 (LPSI
Flow to Loop 1A Cold Leg throttle valve)
ZI-615 C-01 Throttled Position indication for 2-SI-625 (LPSI
Flow to Loop 1B Cold Leg throttle valve)
ZI-625 C-01 Throttled Position indication for 2-SI-635 (LPSI
Flow to Loop 2A Cold Leg throttle valve)
ZI-635 C-01 Throttled Position indication for 2-SI-645 (LPSI
Flow to Loop 2B Cold Leg throttle valve)
ZI-645 C-01 Throttled Lesson Title: Shutdown Cooling System Page 67 of 82 Revision: 4 ID Number: SDC-00-C J. REFERENCES Procedures 1. OP 2207 Plant Cooldown
- 2. OP 2304F CVCS Operation While in Cold Shut Down 3. OP 2306 Safety Injection Tanks 4. OP 2307 LPSI System
- 5. OP 2310 Shutdown Cooling 6. AOP 2572 Loss of SDC
- 7. ARP 2590A Alarm Response for Control Room Panel C-01
Drawings 1. P&ID 25203-26015 SH. 1 of 3 LP Safety Injection Pumps
- 5. P&ID 25203-28115 Logic for 2-SI-657, SH. 23
- 7. P&ID 25203-28115 Logic for 2-SI-651/652, SH. 47
- 8. P&ID 25203-32008 Breaker for 2-SI-651 & 2-SI-652 SH. 11 & 33 Manuals
- 1. Technical Specifications 3.3.2.1 ESF Actuation System Instrumentation.
- 2. Technical Specifications 3.5.2 ECCS Subsystems T avg.
= 300° F 3. Design Basis Document Package - Safety Injection System Volume 1
- 4. MNPS-2 FSAR Chapter 6 Engineered Safety Features Systems
- 5. MNPS-2 FSAR 7.3 Engineered Safety Features Actuation System
- 6. CFR 50 Appendix A criterion 34
- 7. FSAR Chapter 6, Engineered Safety Features Systems
- 8. FSAR Chapter 9, Section 3, Shutdown Cooling System
Operating Experience
- 1. NSAC-52, Residual Heat Removal Experience Review and Safety Analysis
- 2. NSAC--84, Probabilistic Risk Assessment of Decay Heat Removal Systems Lesson Title: Shutdown Cooling System Page 68 of 82 Revision: 4 ID Number: SDC-00-C 3. SOER 85-4, Loss or Degradation of RHR Capability in PWRs. 4. SOER 88-3, Rev. 1, Losses of RHR with Reduced Reactor Vessel Water Level at PWRs.
- 5. SER 12-86 High Cooldown Rate Due To Inaccurate Closed Position Indication On Motor-Operated Valves 6. SER 19-91 Loss Of Decay Heat Removal Capability Due To Inappropriate Maintenance And Testing Lesson Title: Shutdown Cooling System Page 69 of 82 Revision: 4 ID Number: SDC-00-C K. FIGURES Figure 1 02 Shutdown Cooling System 88000775 Figure 2 02 SDC/RCS Interface 88000777 Figure 3 03 Loop 2 Hot Leg 88000776 Figure 4 03 Shutdown Cooling System Elevations 88000915 Figure 5 02 Auxiliary Building -45' Elevation 90000178 Figure 6 00 Emergency Core Cooling Systems 98000250 Figure 7 02 Excess Letdown 88000784 Figure 8 02 Additional Purification 88000783 Figure 9 02 SDC Crossconnect to Spent Fuel Pool 88000785 Figure 10 02 Filling Safety Injection Tanks with SDC 88000786 Figure 11 01 PPC Shutdown Cooling Display 91000094 Figure 12 02 SDC Warmup 88000782 Figure 13 01 Shutdown Cooling Vacuum Cabinet Assembly 91000095 Figure 14 01 RCS Hot Leg Level Monitoring Instrumentation 90000524 Figure 15 01 Magnetic Flag Level Indicator 90000523 Figure 16 01 PPC Shutdown RCS Level Display 91000091 Figure 17 01 PPC Reduced RCS Level Display 91000092 Figure 18 01 PPC Level Display 91000093 Figure 19 01 SDC SG Levels 88000780 Figure 20 03 Boron Equalization 88000781 Figure 21 01 Potential Core Dryout During RCP Repair (Reactor Head On) 88000778 Figure 22 01 Core Dryout During RCP Repair (Reactor Head On & Nozzle Dams Installed) 88000779 Lesson Title: Shutdown Cooling System Page 70 of 82 Revision: 4 ID Number: SDC-00-C L. ATTACHMENTS Attachment 1 Objectives Attachment 2 Controls Interlocks & Automatic Features ESAS Setpoint Requirements
Lesson Title: Shutdown Cooling System Page 71 of 82 Revision: 4 ID Number: SDC-00-C Objectives Terminal Objective Apply the knowledge from classroom training to the normal and abnormal operation of the Shutdown Cooling System in accordance with the plant procedures.
Enabling Learning Objectives PEO Enabling Learning Objectives
- 1. State the purpose of the Shutdown Cooli ng System as given in SDC-00-C. (MB-00878) 2. Given a simplified diagram of the Shut down Cooling System, identify major components and trace the flowpaths for the following operating configurations: (MB-00879) A) Normal single-loop operation with one heat exchanger B) Normal two-loop operation C) Supplementing or providing Spent Fuel Pool cooling D) System warmup E) Boron equalization 3. Describe how the Shutdown Cooling System affe cts or is affected by the following as given in SDC-00-C: (MB-00880)
A) ECCS B) RCS C) RBCCW D) CVCS E) SFPC 4. State the purpose and describe the operating characteristics of the following major Shutdown Cooling System components as given in SDC-00-C: (MB-00881) A) Hot Leg Isolation Valves, 2-SI-651/652/709 B) 2-SI-652 control power disconnect C) LPSI Pumps D) SDC Min Flow Recircs 2-SI-659/660 E) SDC HXs F) SDC HX Flow Control Valve, 2-SI-657 G) SDC Total Flow Control Valve, 2-SI-306 H) LPSI Injection Valves I) SDC Warming Line Isolation, 2-SI-400 J) SDC High Point Evacuation Subsystem 5. State the power supply to the Shutdown Cooling (LPSI) Pumps. (MB-00888)
Lesson Title: Shutdown Cooling System Page 72 of 82 Revision: 4 ID Number: SDC-00-C PEO Enabling Learning Objectives
- 6. Describe the general sequence of events associated with enabling and disabling 2-SI-306/657 as given in OP 2310. (MB-00889) 7. Given a precaution or list of precautions from OP 2310, give the basis for Shutdown Cooling System precautions applicable to the PEO, and describe the methods available to monitor associated parameters. (MB-00884) 8. State the Temperature/Pressure Limits for Shutdown Cooling Initiation and valve interlocks as given in OP 2310. (MB-00887) 9. Describe the general sequence of events associated with startup of the Shutdown Cooling System as given in OP 2207. (MB-00885) 10. Describe the general sequence of events associated with shutdown of the Shutdown Cooling System as given in OP 2310. (MB-00886) 11. Locate each of the following major Shutdown Cooling System components and local controls: (MB-00882) A) SDC HX Flow Control Valve 2-SI-657 B) SDC Total Flow Control Valve 2-SI-306 C) SDC Loop 2 Outlet 2-SI-651/652
- D) SDC Warmup Line Isolation 2-SI-400 E) SDC to SFPC 2-SI-458 F) SDC to CVCS purification 2-SI-040 G) SFPC to SDC 2-SI-442 H) SDC HX A/B SI Inlet 2-SI-452/453 I) SDC HX A/B SI Outlet 2-SI-456/457 J) SDC HX A/B CS Outlet 2-CS-4A/4B K) LPSI Pumps (2)
L) SDC Suction Header High Point Vent 2-SI-043A
- M) Min Flow Isolations 2-SI-659/660 N) SDC Manual Isolation 2-SI-709 O) SDC HX A/B RBCCW Outlet 2-RB-13.1 A/B P) SDC HX A/B RBCCW Outlet Isolation 2-RB-14 A/B Q) SDC Discharge to RWST 2-SI-460 R) LPSI Pump Min Flow Valves 2-SI-449/450
- Inaccessible at power operations, acceptable to discuss or locate on floor plan, drawing, etc.
Lesson Title: Shutdown Cooling System Page 73 of 82 Revision: 4 ID Number: SDC-00-C Terminal Objective Apply the knowledge from classroom training to the normal and abnormal operation of the Shutdown Cooling System in accordance with the plant procedures.
RO Enabling Learning Objectives
- 1. Given a simplified diagram of the Shut down Cooling System, identify major components and trace the flowpaths for the following operating configurations: (MB-03178) A) Normal single-loop operation with one heat exchanger B) Normal two-loop operation C) Supplementing or providing Spent Fuel Pool cooling D) System warmup E) Boron equalization 2. As given in SDC-00-C, describe the functions of the following Shutdown Cooling System Control Room hand or keylock switches at Panel C-01, including how controlled components are affected by each mode or position of the switch: (MB-03187) A) Shutdown Cooling System Suction Isolation keylocks, 2-SI-651, 652 B) Low Pressure Safety Injection Pump A and B control switches C) Minimum Flow Recirculation Valves control switches and bypass keylocks, 2-SI-659, 660 D) Shutdown Cooling System Heat Exc hanger Flow Control keylock, 2-SI-657 E) Shutdown Cooling System Total Flow keylock, 2-SI-306 F) LPSI Injection Throttle Valve control switches 3. As given in SDC-00-C, describe the functions of the following Shutdown Cooling System Control Room controls at Panel C-01, incl uding how controlled components are affected by each mode or position of the control: (MB-03188)
A) Shutdown Cooling Heat Exchanger Flow Controller HIC-3657 B) Shutdown Cooling Flow Controller FIC-306 4. Given a copy of OP 2310, give the basis for each Shutdown Cooling System precaution and describe the methods available to monitor associated parameters. (MB-03191) 5. Explain the reasons for the following considerations when removing a Shutdown Cooling Heat Exchanger from service: (MB-03192)
A) A steady Reactor Coolant System temperature should be maintained B) Only one LPSI Pump should be used C) The evolution cannot be performed during concurrent Reactor Coolant Pump operation D) If Reactor Coolant System temperature is low and decay heat load is high, this operation may cause Reactor Coolant System temperature to rise 6. As given in SDC-00-C, state the purpose for recirculating Safety Injection Headers following termination of shutdown cooling. (MB-03181) 7. As given in SDC-00-C, describe the operational implications of vortexing at the Spent Fuel Lesson Title: Shutdown Cooling System Page 74 of 82 Revision: 4 ID Number: SDC-00-C RO Enabling Learning Objectives Pool suction pipe when supplementing with Shutdown Cooling. (MB-03191) 8. Given any operating condition for the S hutdown Cooling System, state whether the condition requires entry into the Technical Specifications. (MB-03184) 9. Given plant operating conditions or m ode, and given a Shutdown Cooling System Technical Specifications LCO, identify the bases for the LCO and evaluate any implications for plant operation. (MB-03190) 10. Given a list of plant conditions and a copy of the Technical Specifications, determine if any Shutdown Cooling System LCOs are violated and identify the appropriate action statement(s). (MB-03189) 11. As given in SDC-00-C, describe the effect s on the Shutdown Cooling System of a loss or malfunction of the following: (MB-03179) A) 4.16 kVAC Electrical Distribution System B) Vital 120 VAC Electrical Distribution System C) Reactor Building Closed Cooling Water System D) Instrument Air System 12. Describe the effects of a loss or malfunction of the Shutdown Cooling System on the following: (MB-03180)
A) Reactor Coolant System B) Refueling operations C) Refueling Water Storage Tank D) Spent Fuel Pool cooling Lesson Title: Shutdown Cooling System Page 75 of 82 Revision: 4 ID Number: SDC-00-C Attachment 2 - Controls Instrument Number Location Function FIC-306 C-01 Inoperative during normal plant operation (i.e.
Mode 1, 2, & 3). When operative, it can control total Shutdown Cooling System flow by automatically positioning 2-SI-306 to maintain the "set" system
flow. Normal mode will be in manual and open. HIC-657 C-01 Inoperative during normal plant operation (i.e.
Mode 1, 2, & 3). When operative, it controls the
Shutdown Cooling System discharge temperature
by manually positioning 2-SI-657, to control flow
through the Shutdown Cooling Heat Exchangers. HS-3017 C-01 Provides remote manual control of "A" LPSI pump. HS-3018 C-01 Provides remote manual control of "B" LPSI pump. HS-3306 C-01 Key operated switch to override operation of 2-SI-306. Maintained in the "SI" position during
normal plant operation (i.e. Mode 1, 2, & 3). "SI" position fails valve to the open position. HS-3615 C-01 Provides remote manual control for throttling of LPSI Flow to Loop 1A Cold Leg throttle valve. HS-3625 C-01 Provides remote manual control for throttling of LPSI Flow to Loop 1B Cold Leg throttle valve. HS-3635 C-01 Provides remote manual control for throttling of LPSI Flow to Loop 2A Cold Leg throttle valve. HS-3645 C-01 Provides remote manual control for throttling of LPSI Flow to Loop 2B Cold Leg throttle valve. HS-3657 C-01 Key operated switch to override operation of 2-SI-657. Maintained in the "LOCKED CLOSED" position during normal plant operation (i.e. Mode 1, 2, & 3). The "LOCKED CLOSED" position fails the
valve to the closed position. HS-3651 C-01 A key operated switch that provides remote manual control of the shutdown cooling suction line
isolation valve, 2-SI-651.
Lesson Title: Shutdown Cooling System Page 76 of 82 Revision: 4 ID Number: SDC-00-C Instrument Number Location Function HS-3652 C-01 A key operated switch that provides remote manual control of the shutdown cooling suction line isolation valve, 2-SI-652. HS-3659 C-01 Provides remote manual control of 2-SI-659 (minimum flow recirc. valves). HS-3660 C-01 Provides remote manual control of 2-SI-660 (minimum flow recirc. valves). HS-3659A C-01 Blocks a Sump Recirculation Actuation Signal (SRAS) and HS-3659 closure signals to 2-SI-659 (minimum flow recirc. valves) when in the "INOP" position. Maintained in the "INOP" position during
all modes of operation except during SDC
operations and SRAS. HS-3660A C-01 Blocks a Sump Recirculation Actuation Signal (SRAS) and HS-3660 closure signals to 2-SI-660 (minimum flow recirc. valves) when in the "INOP" position. Maintained in the "INOP" position during
all modes of operation except during SDC
operations and SRAS.
Lesson Title: Shutdown Cooling System Page 77 of 82 Revision: 4 ID Number: SDC-00-C - Interlocks & Automatic Features Instrument # Feature LT-3001 LT-3002 LT-3003 LT-3004 Two out of four Refueling Water Storage Tank (RWST) level indications less than setpoint will initiate a Sump Recirculation
Actuation Signal (SRAS) from the Engineered Safeguards
Actuation System (ESAS).
Provided ESAS were not bypassed and a signal were to occur, the following Shutdown Cooling System components would be
affected: LPSI Pump "A" and "B" would trip; SI/CS Minimum flow recirc valves (2-SI-659 & 2-SI-660) would close (provided that HS-3659A and HS-3660A are in the "OPER" position); Containment Sump Outlet Valves (CS-16.1 A/B) open. Shutdown Cooling (SDC) Heat Exchanger RBCCW outlet valves would open (RB-13.1 A/B).
PT-102A PT-102B PT-102C PT-102D Two out of four Pressurizer Pressure indications less than setpoint will initiate SIAS from the Engineered Safeguards Actuation
System (ESAS). SIAS is blocked during SDC operation, but if it
was not blocked, the following components within the LPSI system
or affecting LPSI system performance would be effected: LPSI Pump "A" and "B" start. LPSI injection valves (2-SI-615, 2-SI-625, 2-SI-635, &
2-SI-645) open. ESF Room Fans (F-15A & F-15B) start. PT-103 Prevents the shutdown cooling suction line isolation valve 2-SI-652 from being opened if a high Reactor Coolant System (RCS) pressure condition exists (setpoint: 280 psia increasing). PT-103-1 Prevents the shutdown cooling suction line isolation valve 2-SI-651 from being opened if a high Reactor Coolant System (RCS) pressure condition exists (setpoint: 280 psia increasing).
Lesson Title: Shutdown Cooling System Page 78 of 82 Revision: 4 ID Number: SDC-00-C Instrument # Feature PT-8113 PT-8114 PT-8115 PT-8116 Two out of four Containment Pressure indications greater than setpoint will initiate SIAS from the Engineered Safeguards
Actuation System (ESAS). This cannot be blocked during SDC
operation. Components actuated within the LPSI system or
affecting LPSI system performance are: LPSI Pump "A" and "B" start. LPSI injection valves (2-SI-615, 2-SI-625, 2-SI-635, &
2-SI-645) open. ESF Room Fans (F-15A & F-15B) start. FIC-306 Inoperative during normal plant operation (i.e. Mode 1, 2, & 3).
FIC--306 is used to set valve position (2-SI-306) in the remote manual mode during Shutdown Cooling (SDC)operation. Once
SDC is initiated, 2-SI-306 is maintained fully open by establishing
a full open demand signal using the FIC--306 manual
Lesson Title: Shutdown Cooling System Page 79 of 82 Revision: 4 ID Number: SDC-00-C - ESAS Setpoint Requirements SIGNAL TECH SPEC TRIP SETPOINT Safety Injection Actuation Signal (SIAS)
- setpoints same for CIAS and EBFS Pressurizer Pressure
Containment Pressure
>1714 PSIA lowering
< 4.42 psig rising Main Steam Line Isolation (MSI)
Containment Pressure
Steam Generator Pressure
< 4.42 psig rising
> 572 PSIA lowering Sump Recirculation Actuation Signal (SRAS)
RWST level 46 +
3" above tank bottom (~9.5%)
Containment Spray Actuation Signal (CSAS)
Containment pressure <
9.48 psig rising 4.16 KV Emergency Bus Undervoltage - Level 1 Loss of Normal Power (LNP)
Voltage on bus 24C or 24D >
2912 volts for 2.0 +
0.1 seconds (approx. 70% of rated bus voltage) 4.16 KV Emergency Bus Undervoltage - Level 2 (RSS) Voltage on bus 24C or 24D >
3700 volts for 8 +
2 seconds (approx. 88% of rated bus voltage)
Lesson Title: Shutdown Cooling System Page 1 of 3 Revision: 4 ID Number: SDC-00-C INSTRUCTIONAL MATERIALS COVER SHEET Handou t SDC-00-C, Shutdown Cooling Student Handout Training Aids Visual aids
Instructional Equipment Attendance Sheet Lesson Plan Pointers, Markers etc.
Instructional Objectives and References See Module Report MB 00113 SDC-04-C NLIT Systems, Shutdown Cooling System See Module Report MB 00501 SDC-01-C LOIT Shutdown Cooling System
Lesson Title: Shutdown Cooling System Page 2 of 3 Revision: 4 ID Number: SDC-00-C CONTENT ACTIVITIES/NOTES I. INTRODUCTION Introduce self and lesson. Explain to trainees the overall structure and format of the lesson to
include: - schedule
- break/lunch policy - parking - phone calls/messages
- attendance requirements
- examinations and criteria for satisfactory completion - safety requirements - building evacuations and smoking policy Encourage trainees to ask questions and contribute pertinent information. Make students aware of the OSHA tagging system used in the
Simulator and Technical Training
buildings.
Students must not attempt to manipulate items that are tagged
and/or locked under this system. A) Lesson Overview/Purpose i) Method of Instruction Lecture/discussion ii) Questions/Note taking iii) Instruction period, approximately 50 minutes B) Lesson Objectives/Outline i) Objectives Lesson Title: Shutdown Cooling System Page 3 of 3 Revision: 4 ID Number: SDC-00-C CONTENT ACTIVITIES/NOTES ii) Topic Outline Review Lesson Outline C) Student Reference Materials i) Lesson Text ii) Visual Aids iii) Lesson Objectives D) Assignments/Exams Describe quizzes and examinations i) Study notes and procedures ii) Use objectives to prepare for exam II. LESSON BODY Refer to attached III.
SUMMARY
A. Review Lesson Objectives B. Questions and Answers C. Assignments D. Conduct a System Walkdown PEO-10
SI-651 OPEN C-9 Setpoint:Pressurizer pressure greater than 280 psia with 2-SI-651
openP103-1 deenergizesEffective Date Approval Date 12/11/03 12/16/03Page 1 of 1 ARP 2590A-035Rev. 000AUTOMATIC FUNCTIONS1.None CORRECTIVE ACTIONS1.OBSER2.IF not SYS SUCT SYS ISOL, SI-651" (C-01).3.
4.IF annunciator does not clear ANDREDUCE RCS pressure to less than 280 psia.5.IF annunciator does not clear ANDSUBMIT Priority 2 Trouble Report to I&C Department.SUPPORTING INFORMATION1.Initiating Devices2-SI-651 limit switch and pressurizer pressure, P103-1 bistable, PA-103-1C63X/P103-12.Computer PointsSI651 (digital)3.Procedures4.Control Room Drawings25203-26015, Sheet 3 25203-32008, Sheet 33 5.Annunciator Card Location: TB2-J18 SI-652 OPEN D-9 Setpoint:Pressurizer pressure greater than 280 psia with 2-SI-652
openP103 deenergizesEffective Date Approval Date 12/11/03 12/16/03Page 1 of 1 ARP 2590A-036Rev. 000AUTOMATIC FUNCTIONS1.None CORRECTIVE ACTIONS1.OBSER2.IF not SYS SUCT CTMT ISOL, SI-652" (C-01).3.
4.IF annunciator does not clear ANDopen, REDUCE RCS pressure to less than 280 psia.5.IF annunciator does not clear ANDclosed, SUBMIT Priority 2 Trouble Report to I&C Department.SUPPORTING INFORMATION1.Initiating Devices2-SI-652 limit switch and pressurizer pressure P103, bistable, PA-103-C63X/P1032.Computer PointsSI652 (digital)3.Procedures4.Control Room Drawings25203-26015, Sheet 3 25203-32008, Sheet 33 5.Annunciator Card Location: TB2-J18