Questions on Nuclear fusion & nuclear fission

1. Plutonium-239 is used as a fuel in breeder reactions. It can be formed from uranium-238. The process involves reacting uranium with a neutron to produce uranium-239, which then undergoes beta decay to form neptunium-239, which undergoes further beta decay to give plutonium-239.

(a) Deduce the three nuclear equations for the reactions taking place to form ²³⁹Pu from ²³⁸U.

(b) The half-life for the decay of ²³⁹U to ²³⁹Np is 23.5 minutes. Calculate the percentage of a sample of ²³⁹U remaining after 2 hours 21 minutes.

(c) In a breeder reaction plutonium-239 can react with one neutron to form strontium-90 and barium-147 to produce energy and more neutrons. Deduce how many neutrons are produced for each atom of plutonium-239 that reacts during this process.

2. Superman, a mythical hero, comes from the planet Krypton. However the element krypton, which was discovered in 1898 by Sir William Ramsey, gets its name from the Greek word kryptos which means ‘the hidden one’. One element is named after the star where it was first discovered and that is the element helium. Explain how the presence of helium can be detected in stars and how it can be determined whether or not krypton is also present.

3. (a) The first hydrogen bombs were exploded in the 1950s. Explain why more than 60 years later nuclear fusion is still not being employed for peaceful means whereas nuclear fission power plants have been in operation for almost all of this time.

(b) Assuming that one day nuclear fusion will be used as a peaceful energy source, discuss the advantages that it will have over nuclear fusion.

4. Outline how the following contaminated substances might be treated:

(a) Protective clothing used by a workman to carry out routine maintenance at a nuclear power plant.

(b) Spent fuel rods containing the remnants of plutonium-239 which has a half-life of 24 110 years.

Nuclear fusion & fission questions