Inadequate core cooling system

Question 1

Subcooling margin monitor inputs:

Answer 1

1. Average of 10 highest CETCs
2. RCS WR loop pressure (Avg of PT403 and 405)
3. CNMT pressure
4. CNMT radiation

Question 2

PT403 and 405 are inputs to the subcooling margin monitor. The average of the detectors is used if_______ or ______. Uses only the operating loop if _______.

Answer 2

A and C RCPs are running or secured

Only 1 RCP is running

Question 3

Purpose of ICCS:

Answer 3

1. To provide an advance warning of approach to inadequate core cooling. >1200F Inadequate >700F Degraded
2. Cover the full ICC event from normal ops to core uncovery and restoration.
3. Trend and log sensor outputs.

Question 4

ICCS subsystems (3)

Answer 4

CETC
RVLIS
SMM (Subcooling margin monitor)

Question 5

There are ______ total CETs, _____ A train and ____B train.

Answer 5

65
33 train A
32 train B

Question 6

Train A RVLIS powered from ______ and Train B powered from ______.

Answer 6

131X1 and 132X1

Question 7

Inadequate core cooling BFR C.1
Description
Cause
Symptom
Operator actions

Answer 7

1. High temperature state in the core exceeding design basis accident acceptance criteria that requires operator action to prevent core damage from occurring.
2. Cause:Substantial LOCA resulting in partially/fully uncovered core.
3. Symptom: CETC>1200F
4. Operator actions: establish high head injection, reduce pressure to allow accumulator and low head pump injection, Restart RCPs.

Question 8

Degraded core cooling BFR C.2
Description
Cause
Symptom
Operator actions

Answer 8

1. Superheated steam exiting the core.
2. Cause: substantial LOCA.
3. Symptom CETC>700F
4. Operator actions
   -Establish high head injection
   -Depressurize secondary to reduce primary pressure
   -With RCPs running, allow them to run even if trip criteria met

Question 9

Saturated core cooling BFR C.3
Description

Answer 9

RCS subcooling <700F

Question 10

Sensor 1____
Sensor2 ____

Sensor 3____
Sensor4____
Sensor 5____
Sensor 6____
Sensor 7____
Sensor 8____

Answer 10

Sensor 1 Head 31% (69-99%)
Sensor2 Head 0 %

Sensor 3 81% plenum
Sensor4 55%
Sensor 5 37%
Sensor 6 27%
Sensor 7 15%
Sensor 8 0% Upper core plate

Question 11

RCS WR pressure ____ channels required
CETCs ____ channels per core quadrant required
RV water level 2 trains required with ___ in the head and ___ in the plenum.

Answer 11

2

4 per quadrant

1 in the head
3 in the plenum