<P> Nuclear weapons employ high quality , highly enriched fuel exceeding the critical size and geometry ( critical mass ) necessary in order to obtain an explosive chain reaction . The fuel for energy purposes , such as in a nuclear fission reactor , is very different , usually consisting of a low - enriched oxide material ( e.g. UO ) . </P>
<P> Nuclear weapons employ high quality , highly enriched fuel exceeding the critical size and geometry ( critical mass ) necessary in order to obtain an explosive chain reaction . The fuel for energy purposes , such as in a nuclear fission reactor , is very different , usually consisting of a low - enriched oxide material ( e.g. UO ) . </P>
the minimum mass of a sample of fissionable material necessary to sustain a nuclear chain reaction
the minimum mass of a sample of fissionable material necessary to sustain a nuclear chain reaction
critical mass
critical mass