Skip to content
MathsGenie logo
Quick links
Open app

Course home

  1. A Level
  3. Physics OCR A
  5. Question bank

Nuclear and particle physics

EasyMediumHard
12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849
Question 21

In a nuclear fission reactor designed for marine propulsion, energy is generated through the induced fission of uranium-235 (92235U^{235}_{92}\text{U}92235​U).

a.

Explain the role of the moderator in sustaining a chain reaction in a nuclear fission reactor, and explain how control rods are adjusted to maintain a constant rate of energy release.

[4]
b.

The average mass defect in each individual fission event in this reactor is equivalent to a decrease in mass of 0.215 u0.215\text{ u}0.215 u. A highly enriched fuel element in the reactor contains 15%15\%15% of uranium-235 by mass.

Determine the total thermal energy produced from the fission of all the uranium-235 inside a 1.8 kg1.8\text{ kg}1.8 kg fuel element.

Give your answer to an appropriate number of significant figures.

Data:

  • molar mass of uranium-235 = 0.235 kg mol−10.235\text{ kg mol}^{-1}0.235 kg mol−1
  • 1 u=1.66×10−27 kg1\text{ u} = 1.66 \times 10^{-27}\text{ kg}1 u=1.66×10−27 kg
  • Avogadro constant NA=6.02×1023 mol−1N_A = 6.02 \times 10^{23}\text{ mol}^{-1}NA​=6.02×1023 mol−1
  • speed of light in vacuum c=3.00×108 m s−1c = 3.00 \times 10^8\text{ m s}^{-1}c=3.00×108 m s−1
[4]

Nuclear and particle physics Questions

  1. A Level
  2. /Physics
  3. /Nuclear and particle physics