Module 103 External Dose Control
hour. This problem can be controlled by flushing empty
cylinders to remove residual material.
Neutron External Dose
As uranium is processed in the fuel cycle, it is often
chemically bonded to fluorine to create compounds such as
UF4 and UF6. When uranium atoms in these compounds
decay, they emit alpha particles that are sometimes captured
by the neighboring fluorine atoms. The resulting atom is
unstable and may emit a neutron to gain back its stability.
The neutrons emitted can result in neutron radiation fields
between 0.5 and 4 mrem/h.
The probability of spontaneous fission is small; therefore
exposure is not expected. However, if fission does occur,
such as in a reactor or from experiments, the neutron
radiation is typically contained. Neutron radiation that is
not contained is usually the result of a criticality accident,
which generates potentially fatal doses of gamma radiation.
External Dose Measurements
The radiation from uranium that affects external dose
includes beta, gamma, X-ray and neutron irradiation. An
effective external exposure control program for uranium
requires a variety of radiation detection instruments that are
responsive to these forms of r adiation. Ra diation sur veys
should be performed on a routine basis and during events,
tasks, procedures, or situations that are likely to cause