RQ-C-4973, Reactor Shutdown & Power Ops Part 2

Question 1

Which ONE of the following is NOT an event that Shutdown Margin (SDM) is required to protect against per our licensed design?

A) Fuel element failure
B) Main Steam Line Break (MSLB) transient
C) Inadvertent boron dilution
D) Uncontrolled rod withdrawal from a subcritical condition

Answer 1

A) Fuel element failure

Question 2

Unit 2 performs a rapid power reduction from 100% to 80%.
The crew lowers turbine load and uses control rods to perform the downpower.
Boration is NOT performed.
Describe the changes to Shutdown Margin (Neglect any changes in core fission product reactivity.)

A) SDM will be lower due only to the power defect.
B) SDM will be unchanged regardless of the reactivity effects of control rod insertion and power defect.
C) SDM will be lower due to the combined effects of control rod insertion and power defect.
D) SDM will be greater due only to the insertion of control rods.

Answer 2

B) SDM will be unchanged regardless of the reactivity effects of control rod insertion and power defect.

Question 3

A reactor is operating at 100% power when the crew borates 20 gallons of boric acid to the reactor coolant system (RCS).
Over the next several minutes, the crew adjusts control rod position as necessary to maintain the RCS temperature constant.

When the plant stabilizes, axial power distribution will have shifted toward the _________ of the core and shutdown margin will be __________;

A) bottom; larger
B) top; larger
C) bottom; the same
D) top; the same

Answer 3

B) top; larger