RWCU Flashcards
What is the purpose of RWCU?
Minimize the reduction of heat transfer in core by minimizing deposition of water impurities on heat transfer surfaces
Minimizes secondary sources of beta and gamma radiation by removing corrosion products, fission products and impurities
Where does the RWCU take suction from?
RPV Bottom Head Drain & U2B RR suction (U3A RR Suction) thought portion of SDC piping
Where does RWCU return through?
Small portion of HPCI Piping to B FW Line
What temperature must the RPV water be cooled to? Why? By what?
Cooled to 150F using Non Regen and REgen Hx to prevent Resin decomposition.
RBCCW cooling thru NonRegen Hx
When is the Aux RWCU running?
When RPV pressure <100psig - transfers to main pumps at ~90psig
What provides power to RWCU Aux pump?
Bus 28 (38)
How does RWCU control Reactor Level?
Provides normal means of draining vessel through drain flow regulator to Main Condenser Hotwell or Radwaste.
W/ 40gpm input from CRD and water swell due to decreased moderator density during heatup, RWCU provides reject flro for excess water inventory
What is the purpose of the RWCU Aux Pump?
Ensures flow during low reactor pressure, when system pressure drop is too great to provide necessary NPSH for main ump
What are the trips for Aux RWCU Pump
Low flow trip at <260gpm w/Time Delay because has no Min Flow pathway
Which side of RWCU Regen Hx has RPV supply water? Return water?
RPV suppy on tubes, retun is on Shell
Where does Regen Hx relief valve relieve to?
Main Condenser
What is on the shell side of the Non-Regen Hx? What is it’s outlet temp requirement?
RBCCW, 140F
What is the purpose of the RWCU Pressure COntrol Station?
Lowered pressure to ~80psig using controller in MCR to prevent over pressurizing filters and demins.
How does the RWCU PCV operate?
Valve is air to open and fails closed on loss of IA - normally in AUTO at 60-100psig - w/ bypass if needed
Where do the PCV relief valves exhaust to and what are their setpoints?
160psig - to main condenser
140psig - to RBEDT
What is the purpose of the Drain Flow regulator?
Provides method of rejecting water to main condenser or radwaste
How is the Drain Flow regulator controlled? What isolates it and how does valve fail closed?
Controlls using upstream pressure sensor, will isolate on low pressure of 5# to prevent draining when RPV not at pressure
Valve fails closed on loss of IA.
Controlled via dial controller in MCR
How many RWCU Demins are normally in service?
3 total, 1 normally in service, 1 normally decaying, on being refilled/charged
How many RWCU Recirc Pumps are there? Normally in service? Power sources?
2 total, 1 in service.
Powered by : 2A - Bus 23-1; 2B - Bus 24-1
What is the RWCU Lube Oil Cooled by?
RBCCW
Where do the RWCU Pump Min flows route to?
Surge Tank
How does the RWCU Min FLow Valve respond to system inputs?
Opens when pump feed breaker closed
Fails OPEN on loss of IA (all other AOVs fail closed on loss of air).
What is the purpose of the RWCU surge tank?
Provides a temporary supply of wter to the main RWCU pumps during transient flow operation and minimizes system pressure oscillations.
Provides 15 second water supply on pump trip
Has N2 blanket for level/pressure control -
How is RWCU Surge Tank Level Controlled?
If too high, N2 added
If too low, N2 vented
What is the normal position of and power for the MAIN RWCU vlaves?
Powered from MCC 28-1(38-1) 1 (NO) - RPV Suction 1A (NC) - RPV Suction Bypass 7 (NO) - Return ISolation Powered of 250vdc 2(NO) - Outboard Main Isolation 3(NC) - Aux Pp Suction Vlv Powered from MCC 29-3(39-3) 4(NC) - Aux Pp Discharge 8(NC) - Main Pp Bypass 9A/B (One open, one closed) - Main Pp Discharge 11(NC) - Blow Down(Flow Reg) to Main Condenser 12(NC) - Blow Down (Flow Reg) to Radwaste)
How does the RWCU FCV function?
Air Operated FCV - Air to open, fail closed on loss of IA
Only used in Manual - controlled from dial in MCR - Nominal flow of 650gpm
WHat is the purpose of the RWCU RPV Outless Bypass Valve (1A)?
Opened to pressurize RWCU system prior to opening main valve to alleviate water hammer
What causes a tip to the Main RWCU Pumps?
Low suction Pressure - 10 psig
MOVs 1 OR 7 OR 2&3 closed
Pump Discharge high Temp - 152F
What is required for resetting a RWCU isolation w/RPV at pressure?
Equalize RWCU and pressure <100psi DP
Establish blow down of 65-75 gpm for 15 minutes
Ensure Rx power <95% core thermal power to prevent exceeding Max MWth when adding cool water from RWCU
What causes a RWCU Isolation signal for vlvs 1,1a, 2,3,& 7 vlvs?
PCIS Grp 3
SBLC Control not in OFF
What causes RWCU system isolation with valves 1,1a,2,&3 to close?
Hi Pressure downstream of PCV (130psig)
Hi Temp NRHx Outlet (150F)
Hi Temp Aux Cooling Pp Cooling Outlet - 140F
HELB Isolation
MSL Tunnel Temp HI - 180F
RWCU Area Hi Temp - 150FWhat causes RWCU Aux Pump Trips?
Hi Suction Pressure (>134psig)
MOVs 1,3, OR 7 closed
Low Pp flow <260gpm - can by bypassed
RWCU isolation - due to low flow from MOVs closing
What happens to RWCU on loss of RBCCW?
NRHx lose cooling - potentially isolation of RWCU on hi Temp
RWCU Main and Aux Pumps Lose cooling to seals
What happens to RWCU on loss of IA?
PCV, FCV, and Drain Flow Reg(Blowdown) fail closed
Min Flow Valve Fails open
What happens to RWCU on Loss of I/B?
Loss of RWCU control room instruments - controllers, recorders, and valve control relays
What is a GROUP 3 ISOLATION?
Water - RPV Level Lo - +8”
What happens on loss of power to MOV?
Logic system things valves are full closed and pumps trip
What is the HELB Panel Temp Sensor stpoint?
How many sensors are there? How many required to create system isolatioN?
Power to Panel? Power to logic?
130F
10 total - 5 in each panel - 1 needed to sense HI to isolate system
Powered by 28-1/29-1; Logic from RPS
