Question 1

If a control rod is pulled rapidly out of a nuclear reactor core, what controls the response time (how fast the power level increases)?

Accepted Answer

A)  the speed at which the rod can be removed 
B)  the speed at which neutrons are captured 
C)  the rate at which delayed neutrons from beta decay of fission fragments are emitted 
D)  the rate at which the coolant circulates in the core 
E)  the time between when a neutron is captured and when the nucleus actually fissions 
A)  the speed at which the rod can be removed 
B)  the speed at which neutrons are captured 
C)  the rate at which delayed neutrons from beta decay of fission fragments are emitted 
D)  the rate at which the coolant circulates in the core 
E)  the time between when a neutron is captured and when the nucleus actually fissions

Question 2

Which one of the following represents a fission reaction that can be activated by slow neutrons?

Accepted Answer

A)  238U92 + 1n0 $\rightarrow$ 90Kr36 + 146Cs55 + 2H1 + 1n0 
B)  239Pu94 + 1n0$\rightarrow$ 96Sr38 + 141Ba56 + 31n0 
C)  238U92 $\rightarrow$ 234Th90 + 4He2 
D)  3H1 + 2H1 $\rightarrow$ 4He2 + 1n0 
E)  107Ag47 + 1n0$\rightarrow$ 108Ag47$\rightarrow$ 108Cd48 + 0e-1 
A)  238U92 + 1n0 $\rightarrow$ 90Kr36 + 146Cs55 + 2H1 + 1n0 
B)  239Pu94 + 1n0$\rightarrow$ 96Sr38 + 141Ba56 + 31n0 
C)  238U92 $\rightarrow$ 234Th90 + 4He2 
D)  3H1 + 2H1 $\rightarrow$ 4He2 + 1n0 
E)  107Ag47 + 1n0$\rightarrow$ 108Ag47$\rightarrow$ 108Cd48 + 0e-1

Question 3

When 236U fissions the fragments are:

Accepted Answer

A)  always 140Xe and 94Sr 
B)  always identical 
C)  never 140Xe and 94Sr 
D)  never identical 
E)  none of the above 
A)  always 140Xe and 94Sr 
B)  always identical 
C)  never 140Xe and 94Sr 
D)  never identical 
E)  none of the above

Question 4

Consider the following energies:   Rank them in order of increasing value.

Accepted Answer

A)  1, 2, 3, 4 
B)  3, 4, 2, 1 
C)  1, 2, 4, 3 
D)  2, 1, 4, 3 
E)  2, 4, 1, 3 
A)  1, 2, 3, 4 
B)  3, 4, 2, 1 
C)  1, 2, 4, 3 
D)  2, 1, 4, 3 
E)  2, 4, 1, 3

Question 5

What was the most convincing evidence that a natural nuclear reactor formed two billion years ago in a uranium deposit in Africa?

Accepted Answer

A)  the relative depletion of 235U in the deposit 
B)  the relative depletion of 238U in the deposit 
C)  the relative abundance of lead in the deposit 
D)  the isotopic distribution of neodymium in the deposit 
E)  the appearance of radiation damage in the surrounding rock 
A)  the relative depletion of 235U in the deposit 
B)  the relative depletion of 238U in the deposit 
C)  the relative abundance of lead in the deposit 
D)  the isotopic distribution of neodymium in the deposit 
E)  the appearance of radiation damage in the surrounding rock

Question 6

Fission fragments usually decay by emitting:

Accepted Answer

A)  alpha particles 
B)  electrons and neutrinos 
C)  positrons and neutrinos 
D)  only neutrons 
E)  only electrons 
A)  alpha particles 
B)  electrons and neutrinos 
C)  positrons and neutrinos 
D)  only neutrons 
E)  only electrons

Question 7

The barrier to fission comes about because the fragments:

Accepted Answer

A)  attract each other via the strong nuclear force 
B)  repel each other electrically 
C)  produce magnetic fields 
D)  have large masses 
E)  attract electrons electrically 
A)  attract each other via the strong nuclear force 
B)  repel each other electrically 
C)  produce magnetic fields 
D)  have large masses 
E)  attract electrons electrically

Question 8

Separation of the isotopes of uranium requires a physical, rather than chemical, method because:

Accepted Answer

A)  mixing other chemicals with uranium is too dangerous 
B)  the isotopes are chemically the same 
C)  the isotopes have exactly the same number of neutrons per nucleus 
D)  natural uranium contains only 0.7% 235U 
E)  uranium is the heaviest element in nature 
A)  mixing other chemicals with uranium is too dangerous 
B)  the isotopes are chemically the same 
C)  the isotopes have exactly the same number of neutrons per nucleus 
D)  natural uranium contains only 0.7% 235U 
E)  uranium is the heaviest element in nature

Question 9

When uranium undergoes fission as a result of neutron bombardment, the energy released is due to:

Accepted Answer

A)  oxidation of the uranium 
B)  kinetic energy of the bombarding neutrons 
C)  radioactivity of the uranium nucleus 
D)  radioactivity of the fission products 
E)  a reduction in binding energy 
A)  oxidation of the uranium 
B)  kinetic energy of the bombarding neutrons 
C)  radioactivity of the uranium nucleus 
D)  radioactivity of the fission products 
E)  a reduction in binding energy

Question 10

The binding energy per nucleon:

Accepted Answer

A)  increases for all fission events 
B)  increases for some, but not all, fusion events 
C)  decreases for all fusion events 
D)  decreases for some, but not all, fission events 
E)  remains the same for all fusion events 
A)  increases for all fission events 
B)  increases for some, but not all, fusion events 
C)  decreases for all fusion events 
D)  decreases for some, but not all, fission events 
E)  remains the same for all fusion events

Exam 43: Energy From the Nucleus

If a control rod is pulled rapidly out of a nuclear reactor core, what controls the response time (how fast the power level increases)?

Which one of the following represents a fission reaction that can be activated by slow neutrons?

When 236U fissions the fragments are:

Consider the following energies: Rank them in order of increasing value.

What was the most convincing evidence that a natural nuclear reactor formed two billion years ago in a uranium deposit in Africa?

Fission fragments usually decay by emitting:

The barrier to fission comes about because the fragments:

Separation of the isotopes of uranium requires a physical, rather than chemical, method because:

When uranium undergoes fission as a result of neutron bombardment, the energy released is due to:

The binding energy per nucleon:

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When ²³⁶U fissions the fragments are: