RQ-C-4841 (Excore Nuclear Instrumentation)

Question 1

Reactor power is 100%
Rod control is in manual
All other controls are in automatic

Which ONE of the following will cause the OverTemperature Delta-T trip setpoint to lower?

A) Lowering power to 50% with normal RCS pressure and temperature
B) N42 lower detector fails LOW
C) Auctioneered High Tavg fails LOW
D) RCS Wide Range Pressure channel fails LOW

Answer 1

B) N42 lower detector fails LOW

Question 2

Unit 2 is at 100% power with all systems in automatic control when N44 fails high. What happens?

Answer 2

Rods move in automatically due to power rate mismatch.

Rods do not move back out (due to Tave < Tref) due to C-2 Rod Stop. Outward rod motion is blocked until the Rod Stop Bypass switch is placed in the N44 position.

Question 3

Unit 2 is performing a startup with N41 taken out of service due to a failure. Then CRID 3 is lost. What happens?

Answer 3

Reactor trips due to 2/4 Power Range channels tripped (N43 also lost due to CRID III loss)

Question 4

Describe what happens when NI instrument and control power fuses are pulled

Answer 4

Instrument - if placed in bypass nothing happens, otherwise channel goes to trip
Control - channel goes to trip since there is no bypass

In bypass, control power provides instrument power