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Flashcards in Neutrons Deck (21):
1

QID: P545 (B1845)

Delayed neutrons are fission neutrons that...

A. are released at the instant of fission.

B. are responsible for the majority of U-235 fissions.

C. have reached thermal equilibrium with the surrounding medium.

D. are expelled at a lower average kinetic energy than most other fission neutrons.

D

2

QID: P845 (B1945)

Delayed neutrons are neutrons that...

A. have reached thermal equilibrium with the surrounding medium.

B. are expelled within 1.0 x 10-14 seconds of the fission event.

C. are produced from the radioactive decay of certain fission fragments.

D. are responsible for the majority of U-235 fissions.

C

3

QID: P1145 (B1545)

Which one of the following is a characteristic of a prompt neutron?

A. Expelled with an average kinetic energy of 0.5 MeV.

B. Usually emitted by the excited nucleus of a fission product.

C. Accounts for more than 99 percent of fission neutrons.

D. Released an average of 13 seconds after the fission event.

C

4

QID: P1445 (B1345)

A neutron that is expelled 1.0 x 10-2 seconds after the associated fission event is a __________ neutron.

A. thermal

B. delayed

C. prompt

D. capture

B

5

QID: P1545

A neutron that is expelled 1.0 x 10-6 seconds after the associated fission event is a __________ neutron.

A. thermal

B. prompt

C. delayed

D. capture

C

6

QID: P1945 (B1146)

Which one of the following types of neutrons has an average neutron generation lifetime of 12.5 seconds?

A. Prompt

B. Delayed

C. Fast

D. Thermal

B

7

QID: P2045 (B2046)

In a comparison between a delayed neutron and a prompt neutron produced from the same fission event, the prompt neutron is more likely to... (Assume that both neutrons remain in the core.)

A. require a greater number of collisions to become a thermal neutron.

B. be captured by U-238 at a resonance energy peak between 1 eV and 1000 eV.

C. be expelled with a lower kinetic energy.

D. cause thermal fission of a U-235 nucleus.

A

8

QID: P2145 (B2145)

In a comparison between a delayed neutron and a prompt neutron produced from the same fission event, the prompt neutron is more likely to... (Assume that both neutrons remain in the core.)

A. cause fast fission of a U-238 nucleus.

B. be captured by a U-238 nucleus at a resonance energy between 1 eV and 1000 eV.

C. be captured by a Xe-135 nucleus.

D. cause thermal fission of a U-235 nucleus.

A

9

QID: P2345 (B2345)

A neutron that is released 1.0 x 10-10 seconds after the associated fission event is classified as a __________ fission neutron.

A. delayed

B. prompt

C. thermal

D. spontaneous

A

10

QID: P2445 (B3345)

In a comparison between a prompt neutron and a delayed neutron produced from the same fission event, the delayed neutron requires __________ collisions in the moderator to become thermal; and is __________ likely to cause fission of a U-238 nucleus. (Ignore the effects of neutron leakage.)

A. more; more

B. more; less

C. fewer; more

D. fewer; less

D

11

QID: P2545 (B2545)

In a comparison between a delayed neutron and a prompt neutron produced from the same fission event, the prompt neutron is more likely to...

A. be captured by a Xe-135 nucleus.

B. cause thermal fission of a U-235 nucleus.

C. leak out of the core while slowing down.

D. be captured by a U-238 nucleus at a resonance energy.

C

12

QID: P2645 (B2645)

In a comparison between a delayed neutron and a prompt neutron produced from the same fission event, the delayed neutron is more likely to...

A. leak out of the core.

B. cause fission of a U-238 nucleus.

C. become a thermal neutron.

D. cause fission of a Pu-240 nucleus.

C

13

QID: P2845 (B3145)

During a brief time interval in a typical reactor operating steady-state near the beginning of a fuel cycle, 1.0 x 103 delayed neutrons were emitted.

Approximately how many prompt neutrons were emitted during this same time interval?

A. 1.5 x 105

B. 6.5 x 106

C. 1.5 x 107

D. 6.5 x 108

A

14

QID: P2945 (B2945)

Which one of the following types of neutrons in a reactor is more likely to cause fission of a U-238 nucleus in the reactor fuel? (Assume that each type of neutron remains in the reactor core until it interacts with a U-238 nucleus.)

A. Thermal neutron

B. Prompt fission neutron beginning to slow down

C. Delayed fission neutron beginning to slow down

D. Fission neutron at a U-238 resonance energy

B

15

QID: P3545 (B3545)

During a brief time interval in a typical reactor operating steady-state at the beginning of a fuel cycle, 1.0 x 105 delayed neutrons were emitted.

Approximately how many prompt neutrons were emitted in the reactor during this same time interval?

A. 1.5 x 105

B. 6.5 x 106

C. 1.5 x 107

D. 6.5 x 108

C

16

QID: P4123 (B4123)

A neutron that appears 1.0 x 10-16 seconds after the associated fission event is classified as a __________ fission neutron.

A. delayed

B. prompt

C. thermal

D. spontaneous

B

17

QID: P4923 (B4923)

During a brief time interval in a typical reactor operating steady-state near the beginning of a fuel cycle, 4.25 x 105 delayed neutrons were produced.

Approximately how many prompt neutrons were produced in the reactor during this same time interval?

A. 1.5 x 106

B. 6.5 x 106

C. 1.5 x 107

D. 6.5 x 107

D

18

QID: P5023 (B2245)

In a comparison between a delayed neutron and a prompt neutron produced from the same fissio event, the delayed neutron is more likely to... (Assume that each neutron remains in the core unless otherwise stated.)

A. cause fission of a U-238 nucleus.

B. travel to an adjacent fuel assembly.

C. be absorbed in a B-10 nucleus.

D. leak out of the core.

C

19

QID: P7123 (B7123)

Which one of the following is the process that produces the majority of delayed neutrons in an operating nuclear plant reactor?

A. A thermal neutron is absorbed by a fuel nucleus. After a period of time, the nucleus fissions and releases a delayed neutron.

B. A thermal neutron is absorbed by a fuel nucleus. The fuel nucleus fissions. During the decay process of the fission products, a delayed neutron is emitted.

C. A fast neutron is absorbed by a fuel nucleus. After a period of time, the nucleus fissions and releases a delayed neutron.

D. A fast neutron is absorbed by a fuel nucleus. The fuel nucleus fissions. During the decay process of the fission products, a delayed neutron is emitted.

B

20

QID: P7523 (B7523)

During a brief time interval in a typical reactor operating steady-state near the beginning of a fuel cycle, 4.25 x 1010 prompt neutrons were produced.

Approximately how many delayed neutrons were produced in the reactor during this same time interval?

A. 2.8 x 108

B. 6.5 x 108

C. 2.8 x 109

D. 6.5 x 109

A

21

QID: P7677 (B7677)

Which one of the following is the process that produces the majority of prompt neutrons in an operating nuclear plant reactor?

A. A thermal neutron is absorbed by a fuel nucleus. Almost immediately, the nucleus fissions and emits one or more prompt neutrons.

B. A thermal neutron is absorbed by a fuel nucleus. Almost immediately, the fuel nucleus fissions and produces fission products. During the decay of the fission products, one or more prompt neutrons are emitted.

C. A fast neutron is absorbed by a fuel nucleus. Almost immediately, the nucleus fissions and emits one or more prompt neutrons.

D. A fast neutron is absorbed by a fuel nucleus. Almost immediately, the fuel nucleus fissions and produces fission products. During the decay of the fission products, one or more prompt neutrons are emitted.

A