Question

(a) Which of the following are required characteristics of an isotope to be used as a fuel in a nuclear power reactor? (i) It must emit gamma radiation. (ii) On decay, it must release two or more neutrons. (iii) It must have a half-life less than one hour. (iv) It must undergo fission upon the absorption of a neutron. (b) What is the most common fissionable isotope in a commercial nuclear power reactor?

Short answer

In summary, the required characteristics for an isotope to be used as fuel in a nuclear power reactor are (ii) On decay, it must release two or more neutrons and (iv) It must undergo fission upon the absorption of a neutron. The most common fissionable isotope used in commercial nuclear power reactors is Uranium-235 (\(^{235}\)U).

Step-by-step solution

Part (a)

We will now examine each of the given statements: (i) It must emit gamma radiation. Gamma radiation is not a requirement for an isotope to be considered fuel in a nuclear power reactor. Gamma radiation is a byproduct of the fission process, but it is not necessary for the isotope to emit it in order to be used as fuel. (ii) On decay, it must release two or more neutrons. This is a requirement for an isotope to be used as fuel in a nuclear power reactor. When a nucleus undergoes fission, it produces smaller nuclei and neutrons which are utilized to sustain a controlled chain reaction. Two or more neutrons must be released in order to maintain a continuous chain reaction. (iii) It must have a half-life less than one hour. A short half-life is not a requirement for an isotope to be used as fuel in a nuclear power reactor. In fact, having a short half-life may not be practical as it would require frequent refueling. Isotopes with longer half-lives are more suitable for use as nuclear fuel, as they can provide stable and sustained power production. (iv) It must undergo fission upon the absorption of a neutron. This is another requirement for an isotope to be used as fuel in a nuclear power reactor. When an isotope absorbs a neutron, it should undergo fission, leading to the release of energy and additional neutrons, which will continue the chain reaction. Hence, statements (ii) and (iv) are the required characteristics for an isotope to be used as fuel in a nuclear power reactor.

Part (b)

The most common fissionable isotope used in commercial nuclear power reactors is Uranium-235 (\(^{235}\)U). It is the primary fuel used in nuclear reactors, as it readily undergoes fission upon the absorption of a neutron, producing energy and sustaining the chain reaction necessary for power generation.