It has been estimated that on the order of 10^9 tons of...

It has been estimated that on the order of $10^{9}$ tons of natural uranium is available at concentrations exceeding 100 parts per million, of which 0.7$\%$ is the fissionable isotope 235 $\mathrm{U}$ . Assume all the world's energy use $\left(7 \times 10^{12} \mathrm{J} / \mathrm{s}\right)$ were supplied by 235 $\mathrm{U}$ fission in conventional nuclear reactors, releasing 208 MeV for each reaction. How long would the supply last? The estimate of uranium supply is taken from $\mathrm{K}$ . S. Deffeyes and I. D. MacGregor, "World Uranium Resources," Scientific American $242(1) : 66,1980$ .

Key Concepts

Nuclear Fission

Nuclear fission is the process in which a heavy atomic nucleus splits into smaller nuclei, releasing a large amount of energy in the process. The energy per fission reaction is often quantified in electron volts (usually in MeV), and understanding this process is fundamental for calculating the energy yield from a given amount of nuclear fuel.

Energy Unit Conversion

Energy unit conversion involves translating the energy released in a nuclear reaction (typically given in MeV per fission event) into more conventional units such as Joules. This conversion is critical for comparing the energy output of nuclear reactions with global energy consumption figures, which are generally expressed in Joules.

Uranium Resource Estimation and Isotopic Composition

This concept involves estimating the total amount of a given resource—in this case, natural uranium—and accounting for the fraction that is usable for a specific purpose, such as the fissionable 235U isotope. Understanding the isotopic composition is crucial for determining how much nuclear fuel is available for energy production.

Global Energy Consumption

Global energy consumption provides the scale of energy usage, typically measured in Joules per second (or Watts). It serves as a benchmark against which the potential contribution of nuclear energy can be measured. By comparing the energy yield from nuclear fission to this consumption rate, one can estimate the longevity of a nuclear fuel supply.

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