Nuclear fission and fusionIB MYP Physics: Subtopic test

1. 1
   A power station in France uses uranium-235 as fuel. In the reactor, a slow-moving neutron is absorbed by a uranium-235 nucleus. The nucleus then splits into two smaller nuclei and releases two or three more neutrons and a large amount of energy.

   (a)

   What is the name of this process?

   [1 mark]

   • ANuclear fission
   • BNuclear fusion
   • CRadioactive decay
   • DIonisation

   (b)

   What is the job of the control rods in the reactor?

   [1 mark]

   • ATo slow the neutrons down
   • BTo carry heat away from the fuel
   • CTo absorb neutrons so the rate of fission can be controlled
   • DTo shield workers from radiation

   (c)

   Explain how the release of two or three neutrons in each fission can lead to a chain reaction.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   In southern France, scientists are building an experimental reactor that will fuse isotopes of hydrogen to make helium. The Sun already releases its energy in a similar way.

   (a)

   Which statement describes nuclear fusion?

   [1 mark]

   • AA large nucleus splits into two smaller nuclei
   • BTwo small nuclei join to form a larger nucleus
   • CA nucleus emits an alpha particle
   • DA nucleus absorbs a neutron and splits

   (b)

   Why must the hydrogen nuclei be heated to a very high temperature for fusion to happen?

   [1 mark]

   • ATo make the nuclei radioactive
   • BTo turn the hydrogen into a liquid
   • CTo slow the neutrons down
   • DThe nuclei repel each other, so they need very high speeds to get close enough to join

   (c)

   State two conditions needed in the core of a star for fusion to occur.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A country is considering building a nuclear fission power station that uses uranium-235 as its fuel. Engineers are explaining to the public how it would work and what would happen to the waste.

   (a)

   Outline how a nuclear fission power station produces electricity.

   [3 marks]

   (b)

   Describe why spent fuel and other waste from fission is a problem, and outline two ways of managing it.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A government has money to spend on low-carbon electricity. It can build a new uranium-235 fission power station, or it can fund research into fusion power. Fission power stations already supply electricity to millions of homes, but fusion reactors are still experimental.

   (a)

   Compare nuclear fission and nuclear fusion.

   [6 marks]

   (b)

   Discuss whether the government should spend its money on a new fission power station or on research into fusion power, and give a justified conclusion.

   [6 marks]

   Total for question 4: 12 marks

End of questions