RWCU

Question 1

What is the purpose of RWCU?

Answer 1

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

Question 2

Where does the RWCU take suction from?

Answer 2

RPV Bottom Head Drain & U2B RR suction (U3A RR Suction) thought portion of SDC piping

Question 3

Where does RWCU return through?

Answer 3

Small portion of HPCI Piping to B FW Line

Question 4

What temperature must the RPV water be cooled to? Why? By what?

Answer 4

Cooled to 150F using Non Regen and REgen Hx to prevent Resin decomposition.
RBCCW cooling thru NonRegen Hx

Question 5

When is the Aux RWCU running?

Answer 5

When RPV pressure <100psig - transfers to main pumps at ~90psig

Question 6

What provides power to RWCU Aux pump?

Answer 6

Bus 28 (38)

Question 7

How does RWCU control Reactor Level?

Answer 7

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

Question 8

What is the purpose of the RWCU Aux Pump?

Answer 8

Ensures flow during low reactor pressure, when system pressure drop is too great to provide necessary NPSH for main ump

Question 9

What are the trips for Aux RWCU Pump

Answer 9

Low flow trip at <260gpm w/Time Delay because has no Min Flow pathway

Question 10

Which side of RWCU Regen Hx has RPV supply water? Return water?

Answer 10

RPV suppy on tubes, retun is on Shell

Question 11

Where does Regen Hx relief valve relieve to?

Answer 11

Main Condenser

Question 12

What is on the shell side of the Non-Regen Hx? What is it’s outlet temp requirement?

Answer 12

RBCCW, 140F

Question 13

What is the purpose of the RWCU Pressure COntrol Station?

Answer 13

Lowered pressure to ~80psig using controller in MCR to prevent over pressurizing filters and demins.

Question 14

How does the RWCU PCV operate?

Answer 14

Valve is air to open and fails closed on loss of IA - normally in AUTO at 60-100psig - w/ bypass if needed

Question 15

Where do the PCV relief valves exhaust to and what are their setpoints?

Answer 15

160psig - to main condenser

140psig - to RBEDT

Question 16

What is the purpose of the Drain Flow regulator?

Answer 16

Provides method of rejecting water to main condenser or radwaste

Question 17

How is the Drain Flow regulator controlled? What isolates it and how does valve fail closed?

Answer 17

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

Question 18

How many RWCU Demins are normally in service?

Answer 18

3 total, 1 normally in service, 1 normally decaying, on being refilled/charged

Question 19

How many RWCU Recirc Pumps are there? Normally in service? Power sources?

Answer 19

2 total, 1 in service.

Powered by : 2A - Bus 23-1; 2B - Bus 24-1

Question 20

What is the RWCU Lube Oil Cooled by?

Answer 20

RBCCW

Question 21

Where do the RWCU Pump Min flows route to?

Answer 21

Surge Tank

Question 22

How does the RWCU Min FLow Valve respond to system inputs?

Answer 22

Opens when pump feed breaker closed

Fails OPEN on loss of IA (all other AOVs fail closed on loss of air).

Question 23

What is the purpose of the RWCU surge tank?

Answer 23

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 -

Question 24

How is RWCU Surge Tank Level Controlled?

Answer 24

If too high, N2 added

If too low, N2 vented

Question 25

What is the normal position of and power for the MAIN RWCU vlaves?

Answer 25

``` 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) ```

Question 26

How does the RWCU FCV function?

Answer 26

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

Question 27

WHat is the purpose of the RWCU RPV Outless Bypass Valve (1A)?

Answer 27

Opened to pressurize RWCU system prior to opening main valve to alleviate water hammer

Question 28

What causes a tip to the Main RWCU Pumps?

Answer 28

Low suction Pressure - 10 psig MOVs 1 OR 7 OR 2&3 closed Pump Discharge high Temp - 152F

Question 29

What is required for resetting a RWCU isolation w/RPV at pressure?

Answer 29

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

Question 30

What causes a RWCU Isolation signal for vlvs 1,1a, 2,3,& 7 vlvs?

Answer 30

PCIS Grp 3 | SBLC Control not in OFF

Question 31

What causes RWCU system isolation with valves 1,1a,2,&3 to close?

Answer 31

``` 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 - 150F ```

Question 32

What causes RWCU Aux Pump Trips?

Answer 32

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

Question 33

What happens to RWCU on loss of RBCCW?

Answer 33

NRHx lose cooling - potentially isolation of RWCU on hi Temp | RWCU Main and Aux Pumps Lose cooling to seals

Question 34

What happens to RWCU on loss of IA?

Answer 34

PCV, FCV, and Drain Flow Reg(Blowdown) fail closed | Min Flow Valve Fails open

Question 35

What happens to RWCU on Loss of I/B?

Answer 35

Loss of RWCU control room instruments - controllers, recorders, and valve control relays

Question 36

What is a GROUP 3 ISOLATION?

Answer 36

Water - RPV Level Lo - +8"

Question 37

What happens on loss of power to MOV?

Answer 37

Logic system things valves are full closed and pumps trip

Question 38

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?

Answer 38

130F 10 total - 5 in each panel - 1 needed to sense HI to isolate system Powered by 28-1/29-1; Logic from RPS