Question 1

In order to be useful in sustaining a reaction,the neutrons in a fission reactor must be:
A) released from the reactor.
B) warmed to a higher temperature.
C) accelerated.
D) decelerated.

Accepted Answer

Neutrons in a fission reactor must be decelerated in order to be useful in sustaining a reaction. This is because fast neutrons are more likely to escape the reactor or pass through fuel without causing a fission reaction. By slowing them down, they are more likely to interact with the fuel and sustain the reaction.

Question 2

In a fission reaction,a ²³⁵U nucleus captures a neutron.This results in the creation of the products ¹⁴¹Ba and ⁹²Kr along with how many neutrons? A) 1 B) 2 C) 3 D) 5

Accepted Answer

The fission reaction of a uranium-235 (U-235) nucleus typically involves the nucleus capturing a neutron and then splitting into smaller nuclei, in this case, barium-141 (Ba-141) and krypton-92 (Kr-92), along with the release of additional neutrons. The atomic mass numbers before and after the reaction must be equal due to the conservation of mass. Before the reaction, the total mass number is 235 (from U-235) plus 1 (from the neutron), totaling 236. After the reaction, the total mass number is 141 (from Ba-141) plus 92 (from Kr-92), which adds up to 233. The difference, 236 - 233 = 3, indicates that 3 neutrons are released in the process.

Question 3

Where is the largest untapped source of uranium?
A) Canada
B) Siberia
C) Africa
D) none of the above

Accepted Answer

D

Question 4

The average mass per nucleon is greatest in which of the following elements?
A) hydrogen
B) iron
C) uranium
D) krypton

Accepted Answer

Hydrogen, with only one proton and no neutrons in its most common isotope (protium), has the greatest average mass per nucleon because it lacks the binding energy that contributes to reducing the mass per nucleon in larger atoms.

Question 5

Calculate the energy (in kW⋅h)given off if four kg of plutonium-239 undergoes complete fission.The energy released per fission is 200 MeV.(1 MeV = 1.6 × 10−¹³ J) A) 8.96E+10 kW⋅h B) 5.12E+12 kW⋅h C) 2.02E+16 kW⋅h D) 8.96E+7 kW⋅h E) 5.35E+9 kW⋅h

Accepted Answer

The answer of Calculate the energy (in kW⋅h)given off if...

Question 6

A plasma can be contained in a "magnetic bottle" because it has which of the following properties?
A) high temperature
B) liquid in form
C) made of charged particles
D) made of light elements

Accepted Answer

A plasma can be contained in a magnetic bottle because it is made of charged particles. These particles can be manipulated and controlled by magnetic fields, allowing the plasma to be confined to a certain area.

Question 7

The K-ratio in a uranium fuel reactor is defined as the average number of neutrons from each fission event that will cause another event.In a well-functioning reactor,it is desired that the K-ratio have what value?
A) zero
B) 0.5
C) 1.0
D) 2.0

Accepted Answer

A K-ratio of 1.0 means that each fission event is causing exactly one additional event, which allows for continuous and controlled chain reactions in the reactor. A K-ratio of less than 1.0 means that the reactor is not sustaining its own reaction, while a K-ratio of greater than 1.0 means that the reaction is becoming uncontrolled and potentially dangerous.

Question 8

When uranium fissions into two medium-mass nuclei,the product nuclei tend to have an excess of neutrons when compared to stable nuclei.What type of radioactive decay would one expect from these product nuclei?
A) meson decay
B) negative beta decay
C) positive beta decay
D) proton decay

Accepted Answer

Negative beta decay is expected because the neutron-rich fission products can convert a neutron into a proton, emitting an electron (beta particle) in the process, moving towards a more stable neutron-to-proton ratio.

Question 9

Assume that (i)the energy released per fission event of ²³⁵U is 194 MeV,and (ii)33% of the nuclear energy released in a power plant is ultimately converted to usable electrical energy.Approximately how many fission events will occur in one second in order to provide the two GW electrical power output of a typical power plant? (1 eV = 1.6 × 10−¹⁹ J) A) 4E+23 fission/s B) 2E+20 fission/s C) 6E+25 fission/s D) 2E+15 fission/s E) 8E+17 fission/s

Accepted Answer

The answer of Assume that (i)the energy released per fission...

Question 10

A capture by a target nucleus of uranium-235 is most apt to occur for which type of "bullet" particle?
A) low velocity alpha particle
B) low velocity proton
C) high velocity neutron
D) low velocity neutron

Accepted Answer

Uranium-235 is most likely to capture a low velocity neutron because slow neutrons have a higher probability of being absorbed by the nucleus, leading to fission. High velocity particles or charged particles like protons and alpha particles are less likely to be captured due to repulsive forces and their higher kinetic energy.

Question 11

What characteristic is preferred in the elements contained in moderator materials when used in a nuclear fission reactor?
A) low atomic mass
B) metallic
C) non-metallic
D) high atomic mass

Accepted Answer

The preferred characteristic in a moderator material for a nuclear fission reactor is a low atomic mass. This is because a low atomic mass material slows down the neutrons produced during fission reactions, allowing them to be more easily absorbed by other uranium atoms and sustain the chain reaction. Examples of materials with low atomic mass commonly used as moderators include water, heavy water (deuterium oxide), and graphite.

Question 12

If a self-sustained controlled fusion reaction is to operate,a condition which must be met is that the fuel material be subjected to which of the following condition(s)?
A) confined for sufficient time period
B) have sufficiently high density
C) be at sufficiently high temperature
D) All of the above choices are valid.

Accepted Answer

All of the choices (confined, high density, high temperature) are necessary for a self-sustained controlled fusion reaction to occur. The fuel material needs to be confined for a sufficient enough time period to allow the fusion reaction to take place, the density needs to be high enough to allow for enough collisions between particles, and the temperature needs to be high enough to overcome the Coulomb barrier and allow fusion to occur.

Question 13

The advantage of a fusion reactor when compared to a fission reactor is which of the following?
A) The fuel is cheaper.
B) There is less radioactive waste material.
C) Both choices above are valid.
D) None of the above choices are valid.

Accepted Answer

Fusion reactors have the advantage of using fuels that are more abundant and cheaper than those used in fission reactors, and they produce significantly less long-lived radioactive waste.

Question 14

Which of the following will not influence the rate at which nuclear reactions will occur in a nuclear power plant where the fuel elements are a mixture of ²³⁵U and ²³⁸U? A) the presence of moderating material B) the presence of control rods C) the percentage of ²³⁵U relative to ²³⁸U D) the percentage of the energy that is used to produce electricity

Accepted Answer

The rate at which nuclear reactions occur is directly related to the amount of energy produced, which is determined by the efficiency of the power plant in converting nuclear energy into electrical energy. Therefore, the percentage of the energy that is used to produce electricity will not directly influence the rate of the nuclear reactions within the fuel elements. The other choices - presence of moderating material, presence of control rods, and percentage of ²³⁵U relative to ²³⁸U - will all have an impact on the rate of the nuclear reactions.

Question 15

Which of the following can only occur if the reproduction constant,K,exceeds 1?
A) nuclear meltdown at a nuclear power plant
B) explosive release of radioactivity and steam from a nuclear power plant
C) the explosion of a nuclear bomb
D) All of the above require that K exceed 1.

Accepted Answer

The explosion of a nuclear bomb requires a supercritical mass, meaning the reproduction constant K must exceed 1 to sustain an exponentially growing chain reaction.

Question 16

When comparing product nuclei to reactant nuclei in an exothermal nuclear fusion process,which has the greater binding energy per nucleon?
A) greater in product nuclei
B) greater in reactant nuclei
C) equal in both product and reactant nuclei
D) None of the above choices are valid.

Accepted Answer

In an exothermic nuclear fusion process, the product nuclei have a greater binding energy per nucleon than the reactant nuclei. This phenomenon is explained by the fact that during the fusion process, the nuclei combine to form a single, more massive nucleus, which results in the release of energy in the form of photons. This energy is generated by the process of nuclear fusion and comes from the conversion of a small amount of mass into energy, as described by Einstein's famous equation, E=mc². The resulting product nucleus after fusion has a greater binding energy per nucleon than the original reactants because the energy released during the fusion process is used to bind the nucleons more tightly together in the resulting nucleus, which increases the binding energy per nucleon.

Question 17

In a nuclear reactor which uses the fission process,which of the following is the most likely result in the event of a cooling system failure followed by a nuclear accident?
A) proliferation of plutonium fuel
B) accumulation of critical mass of fissionable material
C) spread of radioactive material into the environment
D) reduction of ozone in upper atmosphere

Accepted Answer

In the event of a cooling system failure followed by a nuclear accident, the most likely result is the spread of radioactive material into the environment. Without proper cooling, the reactor core can overheat and potentially melt down, releasing harmful radioactive material into the air and water. This can lead to serious health and environmental consequences, such as increased rates of cancer and genetic mutations. The proliferation of plutonium fuel or accumulation of critical mass of fissionable material are also potential risks in a nuclear reactor, but they are less likely to occur as a result of a cooling system failure. The reduction of ozone in the upper atmosphere is not directly related to a nuclear accident.

Question 18

The water surrounding the fuel rods in a nuclear fission reactor serves what purpose(s)?
A) coolant
B) moderator
C) Both choices above are valid.
D) None of the choices above are valid.

Accepted Answer

The water surrounding the fuel rods serves as both a coolant and a moderator. Coolant circulates throughout the reactor to remove heat generated by the nuclear reactions, while the moderator slows down the neutrons produced in the reactions to make them more likely to cause additional fissions.

Question 19

In a fission reaction,a ²³⁵U nucleus captures a neutron.What energy is released if the products are ¹³⁹I,⁹⁵Y and two neutrons? (atomic masses: ²³⁵U,235.043 9;¹³⁹I,138.935 0;⁹⁵Y,94.913 4;neutron,1.008 67;and 1 u = 931.5 MeV/c²) A) 123 MeV B) 174 MeV C) 199 MeV D) 218 MeV

Accepted Answer

The answer of In a fission reaction,a ²³⁵U nucleus captures...

Question 20

In a nuclear fission process involving the use of ²³⁹Pu fuel,if the approximate average binding energy per nucleon in the product fragments is 8.8 MeV while that of the fuel atom is 8.1 MeV,what approximate net energy is released per fission? A) 170 MeV B) 270 MeV C) 190 MeV D) 90 MeV E) 50 MeV

Accepted Answer

The answer of In a nuclear fission process involving the...

Quiz 30: Nuclear Energy and Elementary Particles

In order to be useful in sustaining a reaction,the neutrons in a fission reactor must be:

In a fission reaction,a ²³⁵U nucleus captures a neutron.This results in the creation of the products ¹⁴¹Ba and ⁹²Kr along with how many neutrons?

Where is the largest untapped source of uranium?

The average mass per nucleon is greatest in which of the following elements?

Calculate the energy (in kW⋅h) given off if four kg of plutonium-239 undergoes complete fission.The energy released per fission is 200 MeV.(1 MeV = 1.6 × 10−¹³ J)

A plasma can be contained in a "magnetic bottle" because it has which of the following properties?

The K-ratio in a uranium fuel reactor is defined as the average number of neutrons from each fission event that will cause another event.In a well-functioning reactor,it is desired that the K-ratio have what value?

When uranium fissions into two medium-mass nuclei,the product nuclei tend to have an excess of neutrons when compared to stable nuclei.What type of radioactive decay would one expect from these product nuclei?

A capture by a target nucleus of uranium-235 is most apt to occur for which type of "bullet" particle?

What characteristic is preferred in the elements contained in moderator materials when used in a nuclear fission reactor?

If a self-sustained controlled fusion reaction is to operate,a condition which must be met is that the fuel material be subjected to which of the following condition(s) ?

The advantage of a fusion reactor when compared to a fission reactor is which of the following?

Which of the following will not influence the rate at which nuclear reactions will occur in a nuclear power plant where the fuel elements are a mixture of ²³⁵U and ²³⁸U?

Which of the following can only occur if the reproduction constant,K,exceeds 1?

When comparing product nuclei to reactant nuclei in an exothermal nuclear fusion process,which has the greater binding energy per nucleon?

In a nuclear reactor which uses the fission process,which of the following is the most likely result in the event of a cooling system failure followed by a nuclear accident?

The water surrounding the fuel rods in a nuclear fission reactor serves what purpose(s) ?

In a fission reaction,a ²³⁵U nucleus captures a neutron.What energy is released if the products are ¹³⁹I,⁹⁵Y and two neutrons? (atomic masses: ²³⁵U,235.043 9;¹³⁹I,138.935 0;⁹⁵Y,94.913 4;neutron,1.008 67;and 1 u = 931.5 MeV/c²)

In a nuclear fission process involving the use of ²³⁹Pu fuel,if the approximate average binding energy per nucleon in the product fragments is 8.8 MeV while that of the fuel atom is 8.1 MeV,what approximate net energy is released per fission?