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ILOT > EHC - .5 > Flashcards

EHC - .5 Flashcards

1
Q

How much does the EHC reservoir hold?

A

800 gal

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2
Q

What is the setpoint for the EHC relief valves?

A

2000#

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3
Q

What is the normal system pressure for EHC?

A

1600#

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4
Q

At what pressure does the standby EHC pump start?

A

1300#

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5
Q

At what EHC system pressure will the turbine trip?

A

1100#

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6
Q

List the power supplies for the EHC pumps?

A

‘A’ - 10B112
‘B’ - 10B141

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7
Q

What happens when EHC pump strainer is dirty?

A

Internal bypass opens.

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8
Q

List the number of accumulators and their loads. in the EHC system.

A

6 @ reservoir skid for transient pressures.
3 @ BPVs for transients. rated to hold (can also open) all bypass valves for 1 min.
4 @ TCVs.

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9
Q

What is the Generator Load Reject?

A

The load rejection circuitry monitors intermediate pressure (high pressure turbine exhaust pressure as a measure of the turbine energy) and generator stator amperage (as a measure of the energy being produced by the generator). PLU action on valves occurs when the generator current is decreasing at a rate of 1500%/sec. Below 40% of rated intermediate pressure, the PLU circuit cannot actuate.

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10
Q

What are the power supplies for the EHC Logic System?

A

Logic power in 10C363 is auctioneered between 1AD483 and 10Y107.
1AD483 - Primary logic power and 10C651D HMI
10Y107 - Backup power supply and 10C650E HMI

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11
Q

What happens when a load rejection signal is received?

A
  • The load signal is immediately set to minimum.
  • The control valve and intercept valve fast acting solenoids are actuated
  • A direct turbine trip is generated.
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12
Q

How does pressure affect RPV level?

A

Pressure rises, RPV swells.
Pressure lowers, RPV shrinks.

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13
Q

How does RPV pressure affect power?

A

Pressure rises=> Less boiling due to an increase in saturation temp=> Void content goes down=> More moderation=> Prx goes up.
Pressure lowers=> More violent boiling due to a lower saturation temp=> Void content goes up=> Less moderation=> Prx goes down.

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14
Q

Describe the Turbine Speed Control (S1) coincidence.

A

2/3 coincidence.
When 1 is lost, alarms and loss of backup, then becomes 1/2 coincidence.
When 2 are lost, the turbine is tripped.

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15
Q

Describe the Turbine Pressure Control (P1) coincidence.

A

2/3 coincidence.
When 1 is lost, alarms and loss of backup, then becomes 1/2 coincidence.
When 2 are lost, loss of BPV’s and TCV’s a closed.

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16
Q

Describe the operation of speed control during an overspeed condition.

A

100% Normal speed.
V
105% TCV’s are shut.
V
107% CIV’s are shut.
V
108% Overspeed turbine trip.
V
110% Backup overspeed trip.

Control valves will close 20% for every 1% overspeed (100-105%). CIV’s will close 50% for every 1% (105-107%).

17
Q

What occurs at 530 psig EHC oil pressure? is there a time when it is bypassed?

A

RX Scram(1 out of two taken twice)
Bypassed <18%
TCV Control pac disk dump valves

18
Q

Describe the relationship between Rx and throttle pressures.

A

Throttle pressure is linear and Rx pressure is not. 30 pounds for 0-100% stm flow.
3.33% flow/psi error.

19
Q

What is the first scram signal that occurs upon a turbine trip from?

A

the first scram signal to RPS will be from TSV closure (even when from 1100#) when above 18%
When below 18% it will be the high pressure scram

20
Q

How does the Turbine Load Reject(Power to Load Unbalance) initiate a trip?

A

The control valve and intercept valve fast acting solenoids which remove ETS pressure from the TCVs initiating a turbine trip, in addition to load being immediately set to minimum.

21
Q

What is the purpose of a Turbine load reject turbine trip?

A

This is necessary to prevent excessive turbine overspeed during the load reject

22
Q

if the suction strainer for the EHC pump becomes clogged what will happen?

A

There is an internal port which will allow oil flow to the pump

23
Q

What is the EHC oil discharge filter alarm setpoint?

A

100psid

24
Q

What are the EHC Coolers cooled by?

A

TACS

25
Q

What position do the TACS control valves fail to on a loss of air?

A

open

26
Q

How many EHC accumulators are there and what are they used for?

A
  1. 6 on the skid - system surge volume
  2. 3 at the bypass valves (Provide 1 minute of operation to minimize pressure spike on loss of EHC.)
  3. 4 Fast Acting solenoid Control Valve accumulators - for control valve surge volume
27
Q

What is the cross pressurization needle valve?

A

it is a valve in the Duplex 2/3 Trip Device that is - opened to pressurize an out of service manifold from the in-service manifold.

28
Q

What is the sequence that steam is secured to the turbine as it overspeeds?

A

From 100% to 105% speed - The Turbine Control Valves will go from full open to full shut linearly.
From 105% to 107% speed - The Intercept Valves will go from full open to full shut linearly
IE neither use fast acting solenoids

29
Q

Does turbine throttle pressure increase the same rate as reactor pressure?

A

No, throttle pressure is linear and reactor pressure is exponential

30
Q

Can you explain pressure changes using the EHC logic?

A

yes

31
Q

If you lower pressure set, what occurs?

A

control valves close -> RX pressure goes up, power goes up, and level goes down -> Bypass valves open to reduce pressure in the RX

32
Q

How should you maintain your pressure setpoint when operating using the cooldown controller?

A

Maintain the pressure setpoint no more than 50# above throttle pressure

33
Q

Which EHC oil is ported to the servo and to the hydraulic cylinder for valve operation?

A

FAS

34
Q

Upon receipt of a turbine trip signal what happens to the BPVs?

A

simultaneous opening of all nine BPVs will occur within 0.15 seconds

ILOT (93 decks)

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