WordNet
uranium 238
n. the commonest isotope of uranium; it is not fissionable but when irradiated with neutrons it produces fissionable plutonium 239
Usage examples of "uranium 238".
On the outside of the casing were the fins made of spent uranium 238.
Niels Bohr and Princeton's John Wheeler had concluded from theoretical considerations that fission didn't take place in the common uranium 238 isotope, but was restricted to the comparatively rare uranium 235.
The dense uranium 238 fins just outside the Secondary pit also flashed to dense plasma, driving inward through the vacuum, then striking and compressing the tubular containment of more M8U around the central container which held the largest quantity of lithium-deuteride/tritium.