After taking critical data during a reactor startup, the operator establishes a positive 48-second reactor period to increase power to the point of adding heat (POAH). Which one of the following is the approximate amount of reactivity needed to stabilize power at the POAH? (Assume ßeff = 0.00579.)
A. -0.10% delta-K/K
B. -0.12% delta-K/K
C. -0.01% delta-K/K
D. -0.012% delta-K/K
ANSWER: A.
Comment: This question suffers the same defect as B968. Reactivity is not added and the four choices are incorrectly indicated to represent reactivity.
QID: B1966 (P1367) (TOPIC: 292008 KNOWLEDGE: K1.15 [3.7/3.7])
A reactor is critical at 5 x 10-2% power during a cold reactor startup at the beginning of core life. Reactor period is stable at positive 87 seconds. Assuming no operator action, no reactor scram, and no steam release, what will be reactor power 10 minutes later?
A. Below the point of adding heat (POAH)
B. At the POAH
C. Above the POAH but less than 49%
D. Approximately 50%
ANSWER: B.
Comment: The question is technically incorrect because the initial conditions are not specified. Unless there is significant heat loss, which is unlikely in a cold reactor, power will not be at the POAH.
QID: B2569 (TOPIC: 292008 KNOWLEDGE: K1.15 [3.7/3.7])
A reactor is critical at 10-3% power during a cold reactor startup at the beginning of core life. Reactor period is stable at positive 60 seconds. Assuming no operator action, no reactor scram, and no steam release, what will be reactor power 10 minutes later?
A. Below the point of adding heat (POAH)
B. At the POAH
C. Approximately 22%
D. Greater than 100%
ANSWER: B.
Comment: This question suffers the same defect as B1966. Necessary initial conditions are not specified.
QID: B1270 (TOPIC: 292008 KNOWLEDGE: K1.18 [3.8/3.8])
Which one of the following will add the most positive reactivity during a power decrease from 100% to 65% over a 1 hour period? (Assume the power change is performed by changing core recirculation flow rate.)
A. Fuel temperature change
B. Moderator temperature change
C. Fission product poison change
D. Core void fraction change
ANSWER: A.
Comment: This question suffers the same defect as B1065. Reactivity is not added.
QID: B1371 (P1470) (TOPIC: 292008 KNOWLEDGE: K1.18 [3.8/3.8])
With a reactor on a constant period, which one of the following power changes requires the longest time to occur?
A. 1% power to 4% power
B. 5% power to 15% power
C. 20% power to 35% power
D. 40% power to 60% power
ANSWER: A.
Comment: This question is technically incorrect because a constant period does not occur in the power range.
QID: B1570 (P1567) (TOPIC: 292008 KNOWLEDGE: K1.18 [3.8/3.8])
With a reactor on a constant period of 30 seconds, which one of the following power changes requires the least time to occur?
A. 1% power to 6% power
B. 10% power to 20% power
C. 20% power to 35% power
D. 40% power to 60% power
ANSWER: D.
Comment: This question is technically incorrect because a constant period does not occur in the power range.
QID: B1765 (TOPIC: 292008 KNOWLEDGE: K1.18 [3.8/3.8])
Which one of the following lists the method(s) used to add positive reactivity during a normal power increase from 10% to 100%?
A. Control rod withdrawal only
B. Recirculation pump flow increase only
C. Control rod withdrawal and recirculation pump flow increase
D. Recirculation pump flow increase and steaming rate increase
ANSWER: C.
Comment: This question suffers the same defect as B1065. Reactivity is not added.
QID: B2070 (P2071) (TOPIC: 292008 KNOWLEDGE: K1.18 [3.8/3.8])
Neglecting the effects of core Xe-135, which one of the following power changes requires the greatest amount of positive reactivity addition?
A. 3% power to 5% power
B. 5% power to 15% power
C. 15% power to 30% power
D. 30% power to 60% power
ANSWER: D.
Comment: This question suffers the same defect as B1065. Reactivity is not added.
QID: B2072 (P2069) (TOPIC: 292008 KNOWLEDGE: K1.18 [3.8/3.8])
With a reactor on a constant period of 180 seconds, which one of the following power changes requires the longest amount of time to occur?
A. 3% power to 5% power
B. 5% power to 15% power
C. 15% power to 30% power
D. 30% power to 60% power
ANSWER: B.
Comment: This question is technically incorrect because a constant period does not occur in the power range.
QID: B2166 (TOPIC: 292008 KNOWLEDGE: K1.18 [3.8/3.8])
A reactor is operating at 80% power near the end of a fuel cycle. Which one of the following lists the typical method(s) used to add positive reactivity during a normal power increase to 100%?
A. Withdrawal of deep control rods and increasing recirculation flow rate
B. Withdrawal of deep control rods only
C. Withdrawal of shallow control rods and increasing recirculation flow rate
D. Withdrawal of shallow control rods only
ANSWER: A.
Comment: This question suffers the same defect as B1065. Reactivity is not added.
QID: B2270 (TOPIC: 292008 KNOWLEDGE: K1.18 [3.8/3.8])
With a reactor on a constant period, which one of the following power changes requires the shortest time to occur?
A. 1% power to 4% power
B. 5% power to 15% power
C. 20% power to 35% power
D. 40% power to 60% power
ANSWER: D.
Comment: This question is technically incorrect because a constant period does not occur in the power range.
QID: B2470 (TOPIC: 292008 KNOWLEDGE: K1.18 [3.8/3.8])
Neglecting the effects of core Xe-135, which one of the following power changes requires the greatest amount of positive reactivity addition?
A. 3% power to 10% power
B. 10% power to 25% power
C. 25% power to 60% power
D. 60% power to 100% power
ANSWER: D.
Comment: This question suffers the same defect as B1065. Reactivity is not added.
QID: B2669 (P2169) (TOPIC: 292008 KNOWLEDGE: K1.18 [3.8/3.8])
Neglecting the effects of core Xe-135, which one of the following power changes requires the smallest amount of positive reactivity addition?
A. 3% power to 5% power
B. 5% power to 15% power
C. 15% power to 30% power
D. 30% power to 60% power
ANSWER: A.
Comment: This question suffers the same defect as B1065. Reactivity is not added.
QID: B2770 (P2770) (TOPIC: 292008 KNOWLEDGE: K1.18 [3.8/3.8])
With a reactor on a constant period of 180 seconds, which one of the following power changes requires the shortest amount of time to occur?
A. 3% power to 5% power
B. 5% power to 15% power
C. 15% power to 30% power
D. 30% power to 60% power
ANSWER: A.
Comment: This question is technically incorrect because a constant period does not occur in the power range.
QID: B69 (TOPIC: 292008 KNOWLEDGE: K1.19 [3.1/3.2])
For which one of the following events will the Doppler coefficient act first to change the reactivity addition to the core?
A. A control rod drop during reactor power operation
B. The loss of one feedwater heater (extraction steam isolated) during reactor power operation
C. Tripping of the main turbine at 45% reactor power
D. A safety relief valve opening during reactor power operation
ANSWER: A.
Comment: This question suffers the same defect as B1065. Reactivity is not added.
QID: B2670 (TOPIC: 292008 KNOWLEDGE: K1.19 [3.1/3.2])
A reactor is operating with the following initial conditions:
Power level = 100%
Control rod density = 60%
After a load decrease reactor conditions are as follows:
Power level = 80%
Control rod density = 62%
All parameters attained normal steady-state values before and after the power change.
Given the following:
Total control rod
reactivity change = -2.2 x 10-1% delta-K/K
Power coefficient = -1.5 x 10-2% delta-K/K/% power
How much reactivity was added by changes in core recirculation flow rate during the load decrease? (Assume fission product poison reactivity does not change.)
A. 0.0% delta-K/K
B. -5.2 x 10-1% delta-K/K
C. -2.0 x 10-1% delta-K/K
D. -8.0 x 10-2% delta-K/K
ANSWER: D.
Comment: This question suffers the same defect as B1566. Reactivity is not added and the four choices are incorrectly indicated to represent reactivity. In addition, the total control rod reactivity change is incorrectly expressed as reactivity. The power coefficient is incorrectly expressed as reactivity per percent power.
QID: B183 (TOPIC: 292008 KNOWLEDGE: K1.20 [3.3/3.4])
A power increase is initiated by an increase in recirculation flow, causing voids to be swept away and adding positive reactivity. Which one of the following statements best describes the response of the reactivity coefficients?
A. Increasing fuel temperature implies more heat transfer to the coolant; increased moderator temperature causes more void formation, and power stabilizes at a new higher level.
B. Increasing fuel temperature implies more heat transfer to the coolant, thus increasing steam generation; the increased void fraction and fuel temperature add negative reactivity, and power stabilizes at a new higher level.
C. Increasing fuel temperature implies more heat transfer to the coolant, thus increasing steam generation; the increased steam generation raises reactor pressure and moderator temperature, offsetting the decreasing voids, and power stabilizes at a new higher level.
D. Increased moderator and fuel temperature stabilize power at a new higher level.
ANSWER: B.
Comment: This question suffers the same defect as B1065. Reactivity is not added. In addition, the question is poorly worded. There is no "best" answer; there is only one correct answer. And, why not just ask "which of following statements describes the subsequent response?" The reactivity coefficients exist, but it is not clear they respond. Choice B is poorly worded. The void fraction is not "increased" above its initial value, and is probably slightly less than the initial value.
QID: B2371 (P2372) (TOPIC: 292008 KNOWLEDGE: K1.22 [3.5/3.6])
A plant is operating at 90% power at the end of core life when the turbine control system opens the turbine control valves an additonal 5 percent. Reactor power will initially:
A. increase due to positive reactivity addition from the void coefficient only.
B. increase due to positive reactivity addition from the void and moderator temperature coefficients.
C. decrease due to negative reactivity addition from the void coefficient only.
D. decrease due to negative reactivity addition from the void and moderator temperature coefficients.
ANSWER: C.
Comment: This question suffers the same defect as B1065. Reactivity is not added.
QID: B2571 (TOPIC: 292008 KNOWLEDGE: K1.22 [3.5/3.6])
A plant is operating normally at 50% power when a steam break occurs that releases 5% of rated steam flow. Reactor power will initially:
A. increase due to positive reactivity addition from the void coefficient only.
B. increase due to positive reactivity addition from the void and moderator temperature coefficients.
C. decrease due to negative reactivity addition from the void coefficient only.
D. decrease due to negative reactivity addition from the void and moderator temperature coefficients.
ANSWER: C.
Comment: This question suffers the same defect as B1065. Reactivity is not added.
QID: B2071 (TOPIC: 292008 KNOWLEDGE: K1.25 [2.8/2.9])
A plant is operating at 100% power at the end of core life when a single main steam isolation valve suddenly closes. Prior to a reactor scram, reactor power will initially:
A. increase due to positive reactivity addition from the void coefficient only.
B. increase due to positive reactivity addition from the void and moderator coefficients.
C. decrease due to negative reactivity addition from the Doppler coefficient only.
D. decrease due to negative reactivity addition from the Doppler and moderator temperature coefficients.
ANSWER: A.
Comment: This question suffers the same defect as B1065. Reactivity is not added.
QID: B126 (TOPIC: 292008 KNOWLEDGE: K1.27 [3.4/3.5])
A reactor is exactly critical below the point of adding heat. A single rod is inserted into the core. The count rate, as indicated by the source range instruments, will slowly decrease: (Assume no operator or automatic actions.)
A. to zero.
B. to the value of the source neutron strength.
C. to a value above source neutron strength.
D. and then slowly increase to the initial value.
ANSWER: C.
Comment: This question suffers the same defect as B1267. Criticality is an exact condition.