Week 1: Temperature Instrumentation

Question 1

What is the definition of dT? What information does this provide about the RCS?

Answer 1

dT is the difference between the Hot Leg and Cold leg temperatures on a loop-specific basis. This is an indication of reactor power.

Question 2

What is the definition of Tavg? What information does this provide about the RCS?

Answer 2

Tavg is an average of the Hot Leg and Cold leg temperatures on a loop-specific basis. This is an indication of the stored energy in the RCS.

Question 3

How many Narrow Range Hot Leg RTDs are there per loop? Narrow Range Cold Leg RTDs? Why?

Answer 3

3 for the Hot Leg, as the possibility for uneven mixing exists upon exiting the Reactor Vessel.
1 for the Cold Leg, as the RTD is immediately downstream of the RCP outlet, which ensures even mixing.

Question 4

Describe the parameters impacting DNB, and the safe/unsafe direction of each.

Answer 4

Power distribution anomalies - increase gets closer to DNB
Tavg - increase gets closer to DNB
Pressure - decrease gets closer to DNB
Flow - decrease gets closer to DNB

Question 5

What protection setpoints does Tavg feed?

Answer 5

OTDT
OPDT
Low Tavg (Function of P-4)
Low-Low Tavg (P-12)

Question 6

What control signals does Tavg feed?

Answer 6

Rod control
PZR level
Steam Dumps