2
1 Introduction
Uranium belongs to the most important naturally occurring nuclides. It has a
silvery- white colour and is about 70% heavier than lead. One of its isotopes,
235
U
(uranium-235), is the only fissile element found on earth. The use of uranium to
produce nuclear energy, for peaceful, but also for military purposes, has contributed
substantially to changes in the life of mankind over the last 70 years. The huge
energy released by the fission of uranium is associated with the splitting of its
nucleus into two smaller fragments after this nucleus is struck by a neutron. The
creation of these fragments is accompanied by the release of 2–3 neutrons which
can then split other uranium nuclei present in their vicinity.
Uranium is more common than other metals on earth. It can be found in very low
concentration in soil, rocks and water everywhere. There are several places in the
world that have uranium concentrations large enough to be cost-effective to mine.
There are three main isotopes of uranium, namely,
238
U,
235
U and
234
U. The first
two are considered primordial nuclides which existed on earth since the time it was
formed. Their half-lives are sufficiently long so that they have survived to the present day. By far, the most abundant of uranium isotope is
238
U (99.27%), while the
other isotopes are found in the earth’s crust in much lower percentages, namely,
235
U
(0.720%) and
234
U (0.005%). While
238
U and
235
U represent the parent isotopes of
the respective uranium decay chains, the isotope
234
U is formed as one of the decay
products formed within the
238
U series. This is illustrated in Fig. 1.
Fig. 1 The decay chain of
238
U illustrating the formation of all its essential elements which are
finally decayed to form a stable nuclide of
210 Po. The decay of
234
Th,
234
Pa,
226
Ra,
214
Pb,
214
Bi,
210
Pb
and
210 Bi results not only in the emission of charged particles (α or β
−
) but also in the release of the
accompanying gamma photons
J. Sabol
1 Introduction
Uranium belongs to the most important naturally occurring nuclides. It has a
silvery- white colour and is about 70% heavier than lead. One of its isotopes,
235
U
(uranium-235), is the only fissile element found on earth. The use of uranium to
produce nuclear energy, for peaceful, but also for military purposes, has contributed
substantially to changes in the life of mankind over the last 70 years. The huge
energy released by the fission of uranium is associated with the splitting of its
nucleus into two smaller fragments after this nucleus is struck by a neutron. The
creation of these fragments is accompanied by the release of 2–3 neutrons which
can then split other uranium nuclei present in their vicinity.
Uranium is more common than other metals on earth. It can be found in very low
concentration in soil, rocks and water everywhere. There are several places in the
world that have uranium concentrations large enough to be cost-effective to mine.
There are three main isotopes of uranium, namely,
238
U,
235
U and
234
U. The first
two are considered primordial nuclides which existed on earth since the time it was
formed. Their half-lives are sufficiently long so that they have survived to the present day. By far, the most abundant of uranium isotope is
238
U (99.27%), while the
other isotopes are found in the earth’s crust in much lower percentages, namely,
235
U
(0.720%) and
234
U (0.005%). While
238
U and
235
U represent the parent isotopes of
the respective uranium decay chains, the isotope
234
U is formed as one of the decay
products formed within the
238
U series. This is illustrated in Fig. 1.
Fig. 1 The decay chain of
238
U illustrating the formation of all its essential elements which are
finally decayed to form a stable nuclide of
210 Po. The decay of
234
Th,
234
Pa,
226
Ra,
214
Pb,
214
Bi,
210
Pb
and
210 Bi results not only in the emission of charged particles (α or β
−
) but also in the release of the
accompanying gamma photons
J. Sabol