Question 1

Compared to fusion in a tokamak, laser fusion makes use of:

Accepted Answer

A)  smaller particle number densities 
B)  greater particle number densities 
C)  longer confinement times 
D)  higher temperatures 
E)  lower temperatures 
A)  smaller particle number densities 
B)  greater particle number densities 
C)  longer confinement times 
D)  higher temperatures 
E)  lower temperatures B

Question 2

In a nuclear reactor the fissionable fuel is formed into pellets rather than finely ground and mixed with the moderator. This reduces the probability of:

Accepted Answer

A)  non-fissioning absorption of neutrons 
B)  loss of neutrons through the reactor container 
C)  absorption of two neutrons by single fissionable nucleus 
D)  loss of neutrons in the control rods 
E)  none of the above 
A)  non-fissioning absorption of neutrons 
B)  loss of neutrons through the reactor container 
C)  absorption of two neutrons by single fissionable nucleus 
D)  loss of neutrons in the control rods 
E)  none of the above A

Question 3

235U is readily made fissionable by a thermal neutron but 238U is not because:

Accepted Answer

A)  the neutron has a smaller binding energy in 236U 
B)  the neutron has a smaller excitation energy in 236U 
C)  the potential barrier for the fragments is less in 239U 
D)  the neutron binding energy is greater than the barrier height for 236U and less than the barrier height for 239U 
E)  the neutron binding energy is less than the barrier height for 236U and greater than the barrier height for 239U 
A)  the neutron has a smaller binding energy in 236U 
B)  the neutron has a smaller excitation energy in 236U 
C)  the potential barrier for the fragments is less in 239U 
D)  the neutron binding energy is greater than the barrier height for 236U and less than the barrier height for 239U 
E)  the neutron binding energy is less than the barrier height for 236U and greater than the barrier height for 239U D

Question 4

Which of the following chemical elements is not produced by thermonuclear fusion in stars?

Accepted Answer

A)  Carbon (Z = 6, A =12) 
B)  Silicon (Z = 14, A = 28) 
C)  Oxygen (Z = 8, A= 16) 
D)  Mercury (Z = 80, A = 200) 
E)  Chromium (Z = 24, A = 52) 
A)  Carbon (Z = 6, A =12) 
B)  Silicon (Z = 14, A = 28) 
C)  Oxygen (Z = 8, A= 16) 
D)  Mercury (Z = 80, A = 200) 
E)  Chromium (Z = 24, A = 52)

Question 5

In the uranium disintegration series:

Accepted Answer

A)  the emission of a $\beta$- particle increases the mass number A by one and decreases the atomic number Z by one 
B)  the disintegrating element merely ejects atomic electrons 
C)  the emission of an $\alpha$ particle decreases the mass number A by four and decreases the atomic number Z by two 
D)  the nucleus always remains unaffected 
E)  the series of disintegrations continues until an element having eight outermost orbital electrons is obtained 
A)  the emission of a $\beta$- particle increases the mass number A by one and decreases the atomic number Z by one 
B)  the disintegrating element merely ejects atomic electrons 
C)  the emission of an $\alpha$ particle decreases the mass number A by four and decreases the atomic number Z by two 
D)  the nucleus always remains unaffected 
E)  the series of disintegrations continues until an element having eight outermost orbital electrons is obtained

Question 6

The approximate amount of energy emitted in the fission of a nucleus such as 235U is:

Accepted Answer

A)  200 eV 
B)  7.6 MeV 
C)  200 MeV 
D)  760 MeV 
E)  200 GeV 
A)  200 eV 
B)  7.6 MeV 
C)  200 MeV 
D)  760 MeV 
E)  200 GeV

Question 7

Two billion years ago, a natural nuclear reactor formed in a uranium deposit in Africa. Why is it not possible for such a natural reactor to form somewhere on Earth today?

Accepted Answer

A)  It is in fact possible for this to occur. 
B)  Too much uranium has already been mined for this to occur. 
C)  Too much 235U has now decayed for a critical mass to form naturally. 
D)  The remaining uranium deposits are too far underground for this to occur. 
E)  Uranium in the remaining deposits is mixed with too many other elements for this to occur. 
A)  It is in fact possible for this to occur. 
B)  Too much uranium has already been mined for this to occur. 
C)  Too much 235U has now decayed for a critical mass to form naturally. 
D)  The remaining uranium deposits are too far underground for this to occur. 
E)  Uranium in the remaining deposits is mixed with too many other elements for this to occur.

Question 8

Lawson's number is 1020 s.m-3. If the density of deuteron nuclei is 2 *1021 m-3 what should the confinement time be to achieve sustained fusion?

Accepted Answer

A)  16 ms 
B)  50 ms 
C)  160 ms 
D)  250 ms 
E)  20 s 
A)  16 ms 
B)  50 ms 
C)  160 ms 
D)  250 ms 
E)  20 s

Question 9

The barrier to fusion comes about because protons:

Accepted Answer

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

Question 10

The first step of the proton-proton cycle is:

Accepted Answer

A)  1H + 1H $\rightarrow$ 2H 
B)  1H + 1H $\rightarrow$ 2H + e+ + $\nu$ 
C)  1H + 1H $\rightarrow$ 2H + e- + $\nu$ 
D)  1H + 1H $\rightarrow$ 2H + $\gamma$ 
E)  1H + 1H $\rightarrow$  3H + e- + $\nu$ 
A)  1H + 1H $\rightarrow$ 2H 
B)  1H + 1H $\rightarrow$ 2H + e+ + $\nu$ 
C)  1H + 1H $\rightarrow$ 2H + e- + $\nu$ 
D)  1H + 1H $\rightarrow$ 2H + $\gamma$ 
E)  1H + 1H $\rightarrow$  3H + e- + $\nu$

Question 11

In a neutron-induced fission process, delayed neutrons come from:

Accepted Answer

A)  the fission products 
B)  the original nucleus just before it absorbs the neutron 
C)  the original nucleus just after it absorbs the neutron 
D)  the moderator material 
E)  the control rods 
A)  the fission products 
B)  the original nucleus just before it absorbs the neutron 
C)  the original nucleus just after it absorbs the neutron 
D)  the moderator material 
E)  the control rods

Question 12

The overall proton-proton cycle is equivalent to:

Accepted Answer

A)  21H$\rightarrow$ 2H 
B)  41H $\rightarrow$ 4H 
C)  41H $\rightarrow$ 4H +4n 
D)  41H + 2e- $\rightarrow$4He + 2$\nu$ + 6$\gamma$ 
E)  41H + 2e+ $\rightarrow$4He + 2$\nu$ 
A)  21H$\rightarrow$ 2H 
B)  41H $\rightarrow$ 4H 
C)  41H $\rightarrow$ 4H +4n 
D)  41H + 2e- $\rightarrow$4He + 2$\nu$ + 6$\gamma$ 
E)  41H + 2e+ $\rightarrow$4He + 2$\nu$

Question 13

Most magnetic confinement projects attempt:

Accepted Answer

A)  proton-proton fusion 
B)  proton-deuteron fusion 
C)  deuteron-deuteron fusion 
D)  deuteron-triton fusion 
E)  triton-triton fusion 
A)  proton-proton fusion 
B)  proton-deuteron fusion 
C)  deuteron-deuteron fusion 
D)  deuteron-triton fusion 
E)  triton-triton fusion

Question 14

In a subcritical nuclear reactor:

Accepted Answer

A)  the number of fission events per unit time decreases with time 
B)  the number of fission events per unit time increases with time 
C)  each fusion event produces fewer neutrons than when the reactor is critical 
D)  each fusion event produces more neutrons than when the reactor is critical 
E)  none of the above 
A)  the number of fission events per unit time decreases with time 
B)  the number of fission events per unit time increases with time 
C)  each fusion event produces fewer neutrons than when the reactor is critical 
D)  each fusion event produces more neutrons than when the reactor is critical 
E)  none of the above

Question 15

For purposes of a practical (energy producing) reaction one wants a disintegration energy Q that is:

Accepted Answer

A)  positive for fusion reactions and negative for fission reactions 
B)  negative for fusion reactions and positive for fission reactions 
C)  negative for both fusion and fission reactions 
D)  positive for both fusion and fission reactions 
E)  as close to zero as possible for both fusion and fission reactions 
A)  positive for fusion reactions and negative for fission reactions 
B)  negative for fusion reactions and positive for fission reactions 
C)  negative for both fusion and fission reactions 
D)  positive for both fusion and fission reactions 
E)  as close to zero as possible for both fusion and fission reactions

Question 16

Consider all possible fission events. Which of the following statements is true?

Accepted Answer

A)  Light initial fragments have more protons than neutrons and heavy initial fragments have fewer protons than neutrons 
B)  Heavy initial fragments have more protons than neutrons and light initial fragments have fewer protons than neutrons 
C)  All initial fragments have more protons than neutrons 
D)  All initial fragments have about the same number of protons and neutrons 
E)  All initial fragments have more neutrons than protons 
A)  Light initial fragments have more protons than neutrons and heavy initial fragments have fewer protons than neutrons 
B)  Heavy initial fragments have more protons than neutrons and light initial fragments have fewer protons than neutrons 
C)  All initial fragments have more protons than neutrons 
D)  All initial fragments have about the same number of protons and neutrons 
E)  All initial fragments have more neutrons than protons

Question 17

Nuclear fusion in stars produces all the chemical elements with mass numbers less than:

Accepted Answer

A)  56 
B)  66 
C)  70 
D)  82 
E)  92 
A)  56 
B)  66 
C)  70 
D)  82 
E)  92

Question 18

Nuclear fusion in the Sun is increasing its supply of:

Accepted Answer

A)  hydrogen 
B)  helium 
C)  nucleons 
D)  positrons 
E)  neutrons 
A)  hydrogen 
B)  helium 
C)  nucleons 
D)  positrons 
E)  neutrons

Question 19

The energy released in a complete proton-proton cycle is about:

Accepted Answer

A)  3 keV 
B)  30 keV 
C)  3 MeV 
D)  30 MeV 
E)  300 MeV 
A)  3 keV 
B)  30 keV 
C)  3 MeV 
D)  30 MeV 
E)  300 MeV

Question 20

For a controlled nuclear fusion reaction, one needs:

Accepted Answer

A)  high number density n and high temperature T 
B)  high number density n and low temperature T 
C)  low number density n and high temperature T 
D)  low number density n and low temperature T 
E)  high number density n and temperature T = 0 K 
A)  high number density n and high temperature T 
B)  high number density n and low temperature T 
C)  low number density n and high temperature T 
D)  low number density n and low temperature T 
E)  high number density n and temperature T = 0 K

Exam 43: Energy From the Nucleus

Compared to fusion in a tokamak, laser fusion makes use of:

In a nuclear reactor the fissionable fuel is formed into pellets rather than finely ground and mixed with the moderator. This reduces the probability of:

235U is readily made fissionable by a thermal neutron but 238U is not because:

Which of the following chemical elements is not produced by thermonuclear fusion in stars?

In the uranium disintegration series:

The approximate amount of energy emitted in the fission of a nucleus such as 235U is:

Two billion years ago, a natural nuclear reactor formed in a uranium deposit in Africa. Why is it not possible for such a natural reactor to form somewhere on Earth today?

Lawson's number is 1020 s.m-3. If the density of deuteron nuclei is 2 *1021 m-3 what should the confinement time be to achieve sustained fusion?

The barrier to fusion comes about because protons:

The first step of the proton-proton cycle is:

In a neutron-induced fission process, delayed neutrons come from:

The overall proton-proton cycle is equivalent to:

Most magnetic confinement projects attempt:

In a subcritical nuclear reactor:

For purposes of a practical (energy producing) reaction one wants a disintegration energy Q that is:

Consider all possible fission events. Which of the following statements is true?

Nuclear fusion in stars produces all the chemical elements with mass numbers less than:

Nuclear fusion in the Sun is increasing its supply of:

The energy released in a complete proton-proton cycle is about:

For a controlled nuclear fusion reaction, one needs:

Measurement

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Filters

²³⁵U is readily made fissionable by a thermal neutron but ²³⁸U is not because:

The approximate amount of energy emitted in the fission of a nucleus such as ²³⁵U is:

Lawson's number is 10²⁰ s.m^-3. If the density of deuteron nuclei is 2 *10²¹ m^-3 what should the confinement time be to achieve sustained fusion?