noun
uranium-235; U-235
The fissile isotope of uranium used in nuclear reactors and atomic bombs.
ウラン235は核分裂を起こしやすい同位体です。
Uranium-235 is an isotope that readily undergoes nuclear fission.
Kanji numeral spelling; less common but still seen.
Uranium-238 is the more abundant but non-fissile isotope, while uranium-235 is the fissile one used for fuel and weapons.
From English 'uranium-235', combining the element name ウラン (uranium) with the mass number 235.