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TRANSCRIPT
Name: _______________________________________________
Nuclear fission
Date:
Time: Total marks available: Total marks achieved: ______
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Questions
Q1.(a) Control rods and moderators are important parts of nuclear reactors.Draw straight lines linking each part of the reactor with its correct function.
(2)
(b) Describe the process of nuclear fission.
(4)
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(Total for question = 6 marks)
Q2.A nuclear power station generates electricity using the energy released from the nuclear fission of uranium-235, symbol .
(a) How many neutrons are in a nucleus of uranium-235? (1)
A 92
B 143
C 235
D 327
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(b) The diagram shows the process of nuclear fission.
(i) Add labels to the diagram to show the parent nucleus and a daughter nucleus.(2)
(ii) Explain how this fission process can lead to a chain reaction.(3)
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(c) Describe the purpose of the control rods in a nuclear reactor. (2)
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(d) In 1986, an accident occurred at a nuclear power station in Chernobyl, Ukraine.
Workers attempted to shut down the nuclear reactor by fully inserting the control rods into the reactor core.The nuclear reactor design was flawed because the ends of the control rods entering the reactor were made of graphite.(i) Graphite is used as a moderator in a nuclear reactor.
What is the purpose of the moderator in a nuclear reactor?(1)
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(ii) Suggest why there was an accident when the control rods were fully inserted into the reactor core.(2)
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(Total for question = 11 marks)
Q3.The diagram shows the main parts of a nuclear reactor.
(a) Draw a line linking each part of the reactor with its main function.
The first one has been done for you.(2)
(b) State the type of energy released in a fission reaction.
(1)Page 4 of 17
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(c) Explain the role of the moderator in a fission reaction.
(2)
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........................................................................................................................................................... (d) Explain, in terms of neutrons, what is meant by controlled nuclear fission.
(3)
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(Total for question = 8 marks)
Q4.When a neutron collides with a uranium-235 nucleus, nuclear fission can occur.
The equation represents this fission process.
(a) (i) What is meant by the term fission?
(1)
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(ii) Calculate the number of neutrons released during this fission reaction.(2)
(iii) Explain how a chain reaction can occur in uranium-235.(2)
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(iv)With reference to the equation, explain what is meant by a daughter nucleus.(2)
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(b) Barium-144 is a radioactive isotope that emits beta particles.
Explain what happens to the mass (nucleon) number of barium-144 when it emits a beta particle.(2)
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(Total for question = 9 marks)
Q5.In a nuclear reactor, a uranium-235 nucleus absorbs a neutron and fission occurs.
(a) Complete the equation below that shows a typical fission reaction.
(2)
(b) Explain how nuclear fission can lead to a chain reaction.
(3)
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(c) The diagram shows a nuclear reactor.
(i) On the diagram, label the control rods and the shielding.
(2)(ii) Explain why the shielding is needed.
(2)
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(Total for question = 9 marks)Q6.(a) The diagram shows the fuel used in some nuclear reactors.
The fuel is contained inside spheres.The silicon carbide layer of each sphere is designed to contain the fission products for at least one million years.
(i) Give the name of a fuel that could be used.(1)
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(ii) Explain what is meant by the term fission products.(2)
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(iii) Explain why it is important to contain these fission products for such a long time.(2)
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(iv) The graphite layer in every fuel sphere acts as a moderator.What is the function of the moderator in a nuclear reactor?
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(v) The nuclear reactor also contains boron control rods.Explain why it is dangerous to remove most of the control rods from the reactor.
(2)
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(b) The reactor is cooled with helium gas.
The gas enters the reactor at 500 °C.(i) What is this temperature in kelvin?
(1)
temperature = ........................................................... K
(ii) Helium gas enters the reactor at a pressure of 8.40 MPa and leaves the reactor at a temperature of 1170 K.
Calculate the pressure of the helium gas as it leaves the reactor. [assume the volume of the gas does not change]
(3)
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pressure = ........................................................... MPa
(Total for question = 12 marks)
Q7.The diagram shows a neutron colliding with a nucleus of uranium-235, producing anumber of products.
(a) Name the process shown in the diagram.(1)
..............................................................................................................................................(b) Explain how the process shown in the diagram can lead to a chain reaction.
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..............................................................................................................................................(c) This process releases energy. Explain the form that this energy takes.
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.............................................................................................................................................. (d) The energy released in this process can be used in a nuclear power station.
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(i) The pressurised water acts as a coolant. It also acts as a moderator.
What is the purpose of a moderator?(1)
.............................................................................................................................................. ..............................................................................................................................................(ii) Complete the chart below to show the main useful energy transfers in a nuclearpower station.
(4)
(Total for question = 11 marks)
Q8.The diagram shows the main parts of a nuclear reactor.
In the nuclear reactor uranium-235 nuclei undergo fission in a controlled chain reaction.
(a) Describe nuclear fission and how the chain reaction is controlled.Use terms from the diagram to help you.
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(b) State the form of energy that is released during fission.(1)
..............................................................................................................................................(c) How does the shielding improve safety?
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(Total for question = 7 marks)Q9.The diagram shows a nuclear reactor.
(a) A uranium nucleus in the fuel rod may split when a neutron hits it. This process of splitting is known as
(1)
A fission
B moderation
C reflection
D refraction
(b) The control rods control the reaction by
(1)
A absorbing some of the neutrons
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B cooling the reactor vessel
C removing uranium nuclei from the reaction
D slowing the neutrons slightly
(Total for question = 2 marks)
Q10.A student finds this representation of nuclear fission on a website.
(a) Describe what happens when nuclear fission of uranium occurs.
(3)
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(b) The daughter nuclei move off with high speed.
Name the type of energy that this gives them.(1)
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(Total for question = 4 marks)
Q11.The table shows information about three isotopes of uranium.
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(a) (i) Complete the table by filling in the missing numbers.(2)
(ii) Explain what is meant by the term half-life.(2)
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(iii) Suggest why uranium-238 is the most common isotope of uranium.(1)
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(b) Nuclear power stations use a uranium isotope as fuel.What are the products of the fission of uranium nuclei?
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(c) The diagram shows the reactor in a nuclear power station.
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(i) What is the purpose of the moderator?(1)
..............................................................................................................................................(ii) Describe what happens in the reactor when a control rod is removed.
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..............................................................................................................................................(d) There have been several accidents at nuclear power stations. The most serious accident caused an explosion in the reactor. This explosion spread material from inside the reactor to the surrounding area.
Explain why it is difficult to make the surrounding area safe again after a seriousnuclear accident.
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(Total for question = 16 marks)Q12.The diagram shows some of the parts of a nuclear power station.
Describe the process of controlled fission of U-235 in the nuclear reactor.
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..............................................................................................................................................(Total for question = 6 marks)
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Q13.The diagram shows the main parts of a nuclear reactor.
(a) Draw a straight line linking each part of the reactor to its correct purpose.
(4)
(b) Which of these is a nuclear fission product?
(1) A alpha particles B electrons C neutrons D uranium nuclei
(c) Describe the process of nuclear fission.
(4)
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(d) State three ways in which nuclear fission differs from radioactive decay.
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(Total for question = 12 marks)
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