e joules
t libérer
es, pré-
2.
sforma-
sources
bère le
ar cha-
23 Isotopes of uranium
Uranium in its natural state contains more than 99 % ura-
nium 238 and approximately 0.7 % uranium 235.
These two isotopes have different nuclear properties. Ura-
nium 238 undergoes alpha decay; it emits a helium nucleus
He. Uranium 235 is fissile.
1. Why is uranium used in nuclear power plants enriched in
isotope 235?
2. There are several possibilities for the fission of uranium
235. Two of them are given by the following equations:
a. 235U + n → 34... +14Xe + an
94
54
b. 235U+ n → Ce + 144... + 3jn
Fill the blanks in these equations.