AFW

Question 1

What S/G’s does terry turbine supply?

AFW pump 1-2?

AFW pump 1-3?

Via what valves?

Answer 1

TT, 1-4 (LCV-106, 107, 108, 109)

1-2, 1,2 (LCV-110, 111)

1-3, 3,4 (LCV-115, 113)

Via cross connect, each MDAFW pump can supply all for S/G’s

Question 2

Auto starts for MDAFW pumps (2 & 3)?

Answer 2

• SI (18/26 delay), overrides all other starts
• Lo-Lo Ls/g(15%) 2/3, 1/4 S/G (time delay)
• AMSAC. (No delay)
• MFW pumps Trip (No delay)
• Diesel (xfr->dsl)(14 delay), overrides 0 delay starts

Question 3

Trips for MDAFW pumps

Answer 3

O.C.

Load shed

Question 4

What steam traps must be in service for terry turbine to be operable?

Answer 4

• Traps on supply lines (104,105,106)
• Traps off bypass lines of MSIV leads 2 & 3

Question 5

Describe FCV-95 Auto open signal Trips

(auto starts to TDAFW)

Answer 5

Steam supply isolation valve to terry turbine dc powered, panel SD-12

• Lo-Lo Ls/g < 15% 2/3, 2/4 S/G’s
• UV (12 kv bus) 1/2 relays, 2/2 buses
• AMSAC -o.c.

-loss control power, ovrld relay (SI blocks ovrld relay) These Trip bkr for valve=> valve fails as is (not shut)

Question 6

Describe Control scheme for TDAFW LCV’s?

MDAFW LCV’s?

Answer 6

TDAFW valves (ac)

• no control scheme Electro hydraulic operated valves

MDAFW valves (ac)

• median selected Ls/g setpoint
• runout protection, Max valve position based on discharge pressure (1065# = valve must be full closed, ramps up to 1203# where there is no limit, 100% open)
• valve position takes lowest of two
• valve doesn’t get power unless pump bkr closed Or
• valve “cut in”
• if no power valve fails open
• manual tracks auto, if in man when pump is off, pump inoperable b/c auto demand=0 => man demand = 0

Question 7

What is the AFW dedicated volume in the CST?

Are units the same?

why or why not?

Answer 7

U-1 51%(200,000 gal)

U-2 43%(166,000 gal)

U-2 has cold head design => it will take less time to bring unit from HSBY->RHR => lesswater

Question 8

Trips for TDAFW pump

Answer 8

Overspeed Trip throttle valve will shut (FCV-152) on mech overspeed via spring force.

Question 9

Purpose of governor valve for TDAFW pump

Answer 9

FCV-15 maintains 4150-4200 rpm

Question 10

What is power supply to TDAFW pump LCV’s? Why?

Answer 10

480v bus G

Each AFW pump has its own bus/train

TDAFW = G

all LCV AFW pump 2 = H

all LCV AFW pump 3 = F

Question 11

Describe purpose of AFW check valve leak detection

Answer 11

• Where AFW connects to MFW there is check valve on AFW side
• Temp detector up stream of check valve
• alarms if high temp MFW leaks past check valve
• high temp water gets to AFW pumps, pumps could vapor lock when pump tries to start
• AFW designed for CST water < 100 deg, MFW temp >400 deg

Question 12

How is minimum volume ensured on CST’s?

Answer 12

All suctions for loads other than AFW tap off of tank above point that ensures min vol maintained

Question 13

Purpose and design of AFW

Answer 13

• source of FW when MFW unavailable
• safety related means remove decay heat
• c/d RCS to < 350 deg
• TDAFW 870 gpm, 50 recirc, 205/ SG
• MDAFW 460 gpm, 50 recirc, 205/ SG../ pump