Radiological Safety Training for Uranium Facilities
Module 101 Properties of Uranium
Both alpha and beta particles are emitted as part of decay series. For example,
U decays by alpha emission to 234Th; 234Th decays by beta emission to
234mPa; and so on, until stable 206Pb is finally reached.
1. Decay Series
Uranium has two naturally occurring decay series: the "actinium" series, which
has 235U as its parent; and the "uranium" series, which has 238U as its parent.
Many of our everyday encounters with radioactivity come from these decay
series; examples are radon gas and radium. There are also man-made isotopes of
uranium - 232U and 233U. The decay products from these radionuclides must
be considered in the implementation of a radiological control program at a
facility where these uranium nuclides are present.
Uranium is a fissionable material, which means it can undergo nuclear fission.
Nuclear fission is a process in which a very heavy, unstable atom splits in two,
or "fissions". When an atom fissions, one large atom primarily becomes two
smaller atoms, between one and seven neutrons are given off (which may cause
fission in nearby atoms), and a great deal of energy is given off as radiation and
in other forms, such as kinetic energy of the fission fragments. The radiation
created could result in the creation of radiological areas, such as High or Very
High Radiation Areas. Nuclear criticality associated with uranium will be
discussed in greater detail later in the lesson.
Uranium is chemically reactive. It burns in air like magnesium; it is toxic like lead;
and it forms a large variety of chemical compounds. All the isotopes of uranium