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IB Physics HLE.4 FissionQuestion Bank

E.4 Fission

Question 3

[Maximum number: 7]

This question is about nuclear reactions.

Question 3(a)

(a)

A reaction that takes place in the core of a particular nuclear reactor is as shown.

92235U+X→56144Ba+3689Kr+3X{ }_{92}^{235} \mathrm{U}+\mathrm{X} \rightarrow{ }_{56}^{144} \mathrm{Ba}+{ }_{36}^{89} \mathrm{Kr}+3 \mathrm{X}
[ 2 ]

Question 3(a)(i)

(i)

State the nature of X .

[ 1 ]

Question 3(a)(ii)

(ii)

State one form of energy that is instantaneously released in the reaction.

[ 1 ]

Question 3(b)

(b)

In the nuclear reactor, 9.5×10199.5 \times 10^{19} fissions take place every second. Each fission gives rise to 200 MeV of energy that is available for conversion to electrical energy. The overall efficiency of the nuclear power station is 32 %.

[ 2 ]

Question 3(b)(ii)

(i)

Calculate the power output of the nuclear power station.

[ 2 ]

Question 3(c)

(c)

In addition to the U-235, the nuclear reactor contains graphite that acts as a moderator. Explain the function of the moderator.

[ 3 ]

Question 23

[Maximum number: 1]

What is the function of control rods in a nuclear power plant?

A

To slow neutrons down

B

To regulate fuel supply

C

To exchange thermal energy

D

To regulate the reaction rate

Question 23

[Maximum number: 1]

What part of a nuclear power station is principally responsible for increasing the chance that a neutron will cause fission?

A

Moderator

B

Control rod

C

Pressure vessel

D

Heat exchanger

Question 23

[Maximum number: 1]

A nuclear reactor contains atoms that are used for moderation and atoms that are used for control.

What are the ideal properties of the moderator atoms and the control atoms in terms of neutron absorption?

Ideal moderator atom

Ideal control atom

poor absorber of neutrons

poor absorber of neutrons

poor absorber of neutrons

good absorber of neutrons

good absorber of neutrons

poor absorber of neutrons

good absorber of neutrons

good absorber of neutrons

Question 24

[Maximum number: 1]

Control rods are lowered into a thermal nuclear fission reactor to

A

decrease the overall rate of fission occurring in the reactor.

B

increase the overall rate of fission occurring in the reactor.

C

reduce the energies of fission neutrons to thermal values.

D

increase the energies of fission neutrons to thermal values.

Question 27

[Maximum number: 1]

Which of the following is the primary function of the moderator in a nuclear power station?

A

To control the rate of fission reactions

B

To absorb neutrons

C

To prevent the power station from becoming unsafe

D

To slow down neutrons

Question 6

Question 6(b)

(a)

A nuclear power station uses U-235 as fuel. Assume that every fission reaction of U-235 gives rise to 180 MeV of energy.

[ 2 ]

Question 6(b)(i)

(i)

Estimate, in Jkg−1\mathrm{Jkg}^{-1}, the specific energy of U-235.

[ 2 ]

Question 35

[Maximum number: 1]

In a nuclear fission reactor, the role of the moderator is to

A

absorb neutrons to shut down the reactor.

B

speed neutrons up to increase the rate of energy production.

C

slow neutrons down to decrease the rate of energy production.

D

slow neutrons down to make a chain reaction more likely.

Question 35

[Maximum number: 1]

In a nuclear power station, in order to increase the chances of a chain reaction

A

kinetic energy is removed from the neutrons.

B

kinetic energy is given to the neutrons.

C

some neutrons are absorbed.

D

extra neutrons are added.

Question 6

[Maximum number: 5]

This question is about energy sources.

A small island is situated in the Arctic. The islanders require an electricity supply but have no fossil fuels on the island. It is suggested that wind generators should be used in combination with power stations using either oil or nuclear fuel.

Question 6(e)

(a)

Any nuclear fuel available to the islanders must be enriched before it can be used.

Outline why fuel enrichment is needed.

[ 2 ]

Question 6(g)

(b)

A nuclear reactor requires both control rods and a moderator to operate. Outline, with reference to neutrons, one similarity and two differences in the function of each of these components.

[ 3 ]
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