RQ-C-4951, Fundamental Review - Rx Startup Flashcards
A Reactor Startup is in progress following a reactor trip from steady-state full power at the end of cycle. Which one of the following will result in criticality occurring at a higher than estimated critical rod position?
a. RO lowers RCS Boron concentration by 100 ppm
b. Raising Rod Speed by 10%
c. Raising the Steam Dump Pressure Controller to 1015# from 995#.
d. Commencing the startup 30 hours after the trip vice 8 hours after the trip.
c. Raising the Steam Dump Pressur Controller to 1015# from 995#
During a reactor startup, equal increments of reactivity are added, and the count rate is allowed to reach equilibrium each time. Choose the statement that best describes what is observed.
a. The time required to reach equilibrium is longer each time.
b. The time required to reach equilibrium is shorter each time.
c. The change in equilibrium count rate is the same each time.
d. The change in equilibrium count rate is smaller each time.
a. The time required to reach equilibrium is longer each time.
As a subcritical reactor approaches criticality, for equal positive, reactivity additions:
a. The neutron population increase is greater when keff is closer to 1.0
b. The neutron population increase is smaller when keff is closer to 1.0
c. The same increase in neutron population will result as keff approaches 1.0
d. The neutron population decreases until keff exceeds 1.0
a. The neutron population increase is greater when keff is closer to 1.0
Critical Data has just been recorded
The reactor operator then withdrawals Control Bank D Rods and establishes a positive 0.25 DPM startup rate.
Which of the following best describes the final power level of the reactor? (assume no operator action and a constant xenon concentration)
a. Above the point of adding heat and stable
b. Below the point of adding heat and stable
c. Above the point of adding heat and increasing
d. Below the point of adding heat and decreasing
a. Above the point of adding heat and stable
During a reactor startup, equal increments of reactivity are added, and the count rate is allowed to reach equilibrium each time. Choose the statement that best describes what is observed.
A) The time required to reach equilibrium is longer each time
B) The time required to reach equilibrium is shorter each time
C) The change in equilibrium count rate is the same each time
D) The change in equilibrium count rate is smaller each time
A) The time required to reach equilibrium is longer each time
The reactor is critical at a stable power level below the POAH. An unisolable steam line break occurs and 3% of rated steam flow is escaping.
Assuming no reactor trip, which one of the following describes the response of the reactor?
A) Tave will decrease. The reactor will go subcritical
B) Tave will remain the same. The reactor will go to 3% power
C) Tave will decrease. The reactor will go to 3% power
D) Tave will decrease. Power will not change because the reactor was below the POAH
C) Tave will decrease. The reactor will go to 3% power
Describe Boron-10 depletion
- As B10 sits in the core it absorbs neutrons and becomes B11. B11 is not as effective at absorbing neutrons.
- If 1000 ppm boron at BOC the percentage of B10 is ~20%. Given no changes to boron concentration at EOC B10 is ~12%.
Describe subcritical multiplication
- With nothing in the vessel neutron production is equal to source strength. As fuel is added counts rise based on interaction between source and fuel. This rise in counts is subcritical multiplication.
