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21 Cards in this Set
- Front
- Back
- 3rd side (hint)
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A nuclear reactor is initially subcritical with the effective multiplication factor (Keff) equal to 0.998. After a brief withdrawal of control rods, Keff equals 1.002. The reactor is currently...
A. prompt critical. B. supercritical. C. exactly critical. D. subcritical. |
ANSWER: B.
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TOPIC: 192002
KNOWLEDGE: K1.07 [3.1/3.1] QID: P44 (B186) |
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Which one of the following conditions describes a nuclear reactor that is exactly critical?
A. Keff = 0; ΔK/K = 0 B. Keff = 0; ΔK/K = 1 C. Keff = 1; ΔK/K = 0 D. Keff = 1; ΔK/K = 1 |
ANSWER: C.
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TOPIC: 192002
KNOWLEDGE: K1.07 [3.1/3.1] QID: P445 (B247) |
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The ratio of the number of neutrons in one generation to the number of neutrons in the previous generation is the...
A. effective multiplication factor. B. fast fission factor. C. neutron nonleakage factor. D. neutron reproduction factor. |
ANSWER: A.
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TOPIC: 192002
KNOWLEDGE: K1.08 [2.6/2.6] QID: P45 |
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The effective multiplication factor (Keff) can be determined by dividing the number of neutrons produced from fission in the third generation by the number of neutrons produced from fission in the ____________ generation.
A. first B. second C. third D. fourth |
ANSWER: B.
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TOPIC: 192002
KNOWLEDGE: K1.08 [2.6/2.6] QID: P1346 (B1447) |
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end of one generation to the number of fission neutrons at the __________ of the __________ generation.
A. end; previous B. beginning; next C. beginning; previous D. end; next |
ANSWER: A.
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TOPIC: 192002
KNOWLEDGE: K1.08 [2.6/2.6] QID: P1846 (B847) |
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A thermal neutron is about to interact with a U-238 nucleus in an operating nuclear reactor core. Which one of the following describes the most likely interaction and the effect on core Keff?
A. The neutron will be scattered, thereby leaving Keff unchanged. B. The neutron will be absorbed and the nucleus will fission, thereby decreasing Keff. C. The neutron will be absorbed and the nucleus will fission, thereby increasing Keff. D. The neutron will be absorbed and the nucleus will decay to Pu-239, thereby increasing Keff. |
ANSWER: A.
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TOPIC: 192002
KNOWLEDGE: K1.08 [2.6/2.6] QID: P2647 (B2647) |
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A nuclear power plant is currently operating at equilibrium 80 percent power near the end of its fuel cycle. During the next 3 days of equilibrium power operation no operator action is taken. How will core Keff be affected during the 3-day period?
A. Core Keff will gradually increase during the entire period. B. Core Keff will gradually decrease during the entire period. C. Core Keff will tend to increase, but inherent reactivity feedback will maintain Keff at 1.0. D. Core Keff will tend to decrease, but inherent reactivity feedback will maintain Keff at 1.0. |
ANSWER: D.
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TOPIC: 192002
KNOWLEDGE: K1.08 [2.6/2.6] QID: P3046 (B3147) |
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A 1.5 MeV neutron is about to interact with a U-238 nucleus in an operating nuclear reactor core. Which one of the following describes the most likely interaction and the effect on core Keff?
A. The neutron will be scattered, thereby leaving Keff unchanged. B. The neutron will be absorbed and the nucleus will fission, thereby decreasing Keff. C. The neutron will be absorbed and the nucleus will fission, thereby increasing Keff. D. The neutron will be absorbed and the nucleus will decay to Pu-239, thereby increasing Keff. |
ANSWER: A.
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TOPIC: 192002
KNOWLEDGE: K1.08 [2.6/2.6] QID: P6424 (B6424) |
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During core refueling, burnable poisons are often installed in the core to help control Kexcess. Why are more burnable poison rods installed during fuel load for the first fuel cycle than for subsequent fuel cycles?
A. Control rod worth is lower at the beginning of subsequent fuel cycles. B. More fuel reactivity is present at the beginning of subsequent fuel cycles. C. More fission product poisons are present at the beginning of subsequent fuel cycles. D. Reactor coolant boron concentration is higher at the beginning of subsequent fuel cycles. |
ANSWER: C.
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TOPIC: 192002
KNOWLEDGE: K1.09 [2.5/2.7] QID: P546 |
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Select the equation that defines K-excess (excess reactivity).
A. Keff + 1 B. Keff - 1 C. Keff(1-SDM) D. 1/(1-Keff) |
ANSWER: B.
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TOPIC: 192002
KNOWLEDGE: K1.09 [2.5/2.7] QID: P646 (B1848) |
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Which one of the following combinations of critical core conditions indicates the most excess reactivity exists in the core?
Control RCS Boron .............Rod Position Concentration A. 25% inserted 500 ppm B. 50% inserted 500 ppm C. 25% inserted 1,000 ppm D. 50% inserted 1,000 ppm |
ANSWER: D.
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TOPIC: 192002
KNOWLEDGE: K1.09 [2.5/2.7] QID: P946 |
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The following are combinations of critical conditions that exist for the same nuclear reactor operating at the point of adding heat at different times in core life. Which one of the following
combinations indicates the least amount of excess reactivity present in the core? Control RCS Boron .............Rod Position Concentration A. 25% inserted 500 ppm B. 25% inserted 1,000 ppm C. 50% inserted 500 ppm D. 50% inserted 1,000 ppm |
ANSWER: A.
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TOPIC: 192002
KNOWLEDGE: K1.09 [2.5/2.7] QID: P1147 |
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Which one of the following is a reason for installing excess reactivity (Kexcess) in a reactor core?
A. To compensate for the conversion of U-238 to Pu-239 over core life. B. To compensate for burnout of Xe-135 and Sm-149 during power changes. C. To ensure the fuel temperature coefficient remains negative throughout core life. D. To compensate for the negative reactivity added by the power coefficient during a power increase. |
ANSWER: D.
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TOPIC: 192002
KNOWLEDGE: K1.09 [2.5/2.7] QID: P1246 (B2048) |
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A nuclear reactor is operating at full power at the beginning of fuel cycle. A neutron has just been absorbed by a U-238 nucleus at a resonance energy of 6.7 electron volts. Which one of the following describes the most likely reaction for the newly formed U-239 nucleus and the effect of this reaction on Kexcess?
A. Decays over several days to Pu-239, which increases Kexcess. B. Decays over several days to Pu-240, which increases Kexcess. C. Immediately undergoes fast fission, which decreases Kexcess. D. Immediately undergoes thermal fission, which decreases Kexcess. |
ANSWER: A.
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TOPIC: 192002
KNOWLEDGE: K1.09 [2.5/2.7] QID: P2847 (B2747) |
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Which one of the following is a benefit of installing excess reactivity (Kexcess) in a nuclear reactor core?
A. Ensures that sufficient control rod negative reactivity is available to shut down the reactor. B. Ensures that the reactor can be made critical during a peak xenon condition after a reactor trip. C. Ensures that positive reactivity additions result in controllable reactor power responses. D. Ensures that the U-235 fuel enrichment is the same at the beginning and the end of a fuel cycle.. |
ANSWER: B.
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TOPIC: 192002
KNOWLEDGE: K1.09 [2.5/2.7] QID: P3547 (B3547) |
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Shutdown margin is the actual amount of reactivity...
A. inserted by burnable poisons at beginning of life. B. due to dissolved boron in the reactor coolant system. C. by which the reactor is subcritical. D. which would be inserted by shutdown bank rods. |
ANSWER: C.
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TOPIC: 192002
KNOWLEDGE: K1.10 [3.2/3.6] QID: P127 |
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When determining the shutdown margin for an operating nuclear reactor, how many control rods are assumed to remain fully withdrawn?
A. A single control rod of the highest reactivity worth. B. A symmetrical pair of control rods of the highest reactivity worth. C. A single control rod of average reactivity worth. D. A symmetrical pair of control rods of average reactivity worth. |
ANSWER: A.
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TOPIC: 192002
KNOWLEDGE: K1.10 [3.2/3.6] QID: P245 (B248) |
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With a nuclear power plant operating at 85 percent power and rod control in Manual, the operator borates the reactor coolant system an additional 10 ppm. Assuming reactor power does not change during the boration, shutdown margin will...
A. decrease and stabilize at a lower value. B. decrease, then increase to the original value as coolant temperature changes. C. increase and stabilize at a higher value. D. increase, then decrease to the original value as coolant temperature changes. |
ANSWER: C.
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TOPIC: 192002
KNOWLEDGE: K1.10 [3.2/3.6] QID: P345 |
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With a nuclear power plant operating at 75 percent power and rod control in Manual, the operator dilutes reactor coolant system (RCS) boron concentration by 5 ppm. Assuming that reactor power does not change, shutdown margin will...
A. increase and stabilize at a higher value. B. increase, then decrease to the original value as coolant temperature changes. C. decrease and stabilize at a lower value. D. decrease, then increase to the original value as coolant temperature changes. |
ANSWER: C.
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TOPIC: 192002
KNOWLEDGE: K1.10 [3.2/3.6] QID: P746 |
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A nuclear power plant is operating with the following initial conditions:
• Reactor power is 50 percent • Rod control is in manual • Reactor coolant system (RCS) boron concentration is 600 ppm Disregarding the effects of fission product poisons, which one of the following will result in a decrease in the available shutdown margin once the plant stabilizes? A. Reactor power is reduced to 45 percent with final RCS boron concentration at 620 ppm. B. Reactor power is increased to 55 percent with final RCS boron concentration at 580 ppm. C. Control rods are withdrawn 3 inches with no change in steady-state reactor power or RCS boron concentration. D. Control rods are inserted 3 inches with no change in steady-state reactor power or RCS boron concentration. |
ANSWER: B.
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TOPIC: 192002
KNOWLEDGE: K1.10 [3.2/3.6] QID: P1747 |
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ON page 10 question P2347
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on page 10 p2347
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