MANAGEMENT OF NORM IN THE PETROLEUM INDUSTRY Akpojevwa Tega Naomi, october 2016 | Page 15

electrons. They are a relatively heavy (mass 4), high energy (MeV) particles
that are doubly (positively) charged and lose energy very quickly in matter.
They can easily be shielded with a piece of paper, gloves, disposable coverall or
the dead outer layer of your skin. The primary health concern is inhalation and
ingestion of α-particles into the body which places them in direct contact with
essential layers of living tissue (e.g. oxygen or nutrients exchange layers in lung
or intestine).
• Beta (β) particles: β-particles are subatomic particles ejected from the nucleus
of some radioactive atoms. They are equivalent to electrons. The difference is
that β-particles originate from the nucleus and electrons originate from
electronic shells (orbitals) outside the nucleus.
It is their excess energy, which causes harm to living cells. When transferred,
this energy can break chemical bonds and form ions.
They can be effectively shielded with a thin piece of aluminium, steel or plastic
but unlike alpha particles will not be fully shielded by coveralls and gloves.
• Gamma (γ) photons: γ-photon emission often accompanies the emission of β-
and occasionally α-particles due to relaxation of the excited nuclear state, in
which the newly formed NORM is created. γ-photons can travel an indefinite
distance in air and needs to be shielded with material with a high electron
density, like Lead (Pb).
Due to their long range in air γ-photons are considered as an external irradiation
hazard to the human body. Only γ-photons that are stopped in living tissue may
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