EHC

Question 1

How many EHC pumps are there per unit? What is their power source?

Answer 1

2 - A - Bus 25, B - Bus 27

Question 2

What is the purpose of the EHC Filters?

Answer 2

On pump discharge header to remove water, acis, and chlorine from fluid

Question 3

Where can the EHC Filter Transfer Pump be started and stopped from?

Answer 3

MCR

Question 4

What provides cooling to the EHC Oil Coolers?

Answer 4

TBCCW by TCV controlling at between 110 and 126F

Question 5

How many Accumulators does the EHC system have?

What is their purpose?

Answer 5

11 - system to maintain constant system pressure durign transients
BPV accumulators provide enough fluid to hold valves open 1min on loss of EHC pumps

Question 6

What are the pressures for the EHC accumulators?

Answer 6

4 at EHC skid - 1000psig
BPV - 2 charged to 900psig, 1 to 500psig
4 at each Turb Control Valve charged to 1000psig

Question 7

Which EHC/Turb Valves are Throttleable?

Answer 7

SV 2, all control valves - Intercept valves 1, 3, & 5

Question 8

What will cause a slow close on the throttleable Turb Valves?

Answer 8

Clogged strainers on Servo valve, loss of electrical signal to servo, loss of EHC fluid/pressure to servo

Question 9

How does EHC respond on Turb. Trip?

Answer 9

Turb Trip Manifold assembly blocks ETS pressure which causes disk dump valve to open and shutoff valve to close

ETS depressurizes, closing EHC controlled valves except BPVs
ETS pressure released from Air Relay dump valve which repositions extration steam valves
Scram signal sent to RPS when Stop valves less than 90% open if RTP >38.5%

Question 10

How is the Turbine Trip Manifold Assembly functions?

Answer 10

Arranged hydraulically so that if any 2 of 3 solenoids de-energize, turbine will trip - solenoids energize to run/ de-energize to trip

Question 11

EHC Pressure actuation interlocks?

Answer 11

If discharge pressure on running pump <1300#, standby autostart
Low oil pressure below 1100#, turbine trip
FASTC <590# at Cont. Valves - Turbine Valve Fast Closure Scram

Question 12

What is a Power-Load Unbalance Scram?

Answer 12

If Rx Power >38.5% and there is a 40% mismatch between Gen. Amps and pressure sensed at Control Valves - Scram
If <38.5 %, then BPVs and House Loads can handle.

Question 13

What supplies the Throttleable valves with throttling oil

Answer 13

FJS

Question 14

Which Turbine Vavles are throttleable?

Answer 14

2 Stop Valve
Intercept Valves 1, 3, 5
Control Valves
BPV

Question 15

What happens on a loss of FJS?

Answer 15

pressure drop in servo valves and valves drift closed