Shielding
Shielding is any material used to reduce the radiation reaching the
operator from a radioactive source. While some types of radiation
(such as alpha particles) may be stopped by a single sheet of paper,
other radiation (such as photons and neutrons) require much more
shielding. Dense materials, such as lead, shield photons. Materials
containing large amounts of hydrogen, such as polyethylene, shield
neutrons. The Model 3430 gauge has shielding built into the system
to reduce the exposure.
MONITORING RADIATION
In the United States, anyone working with or near radioactive
materials is subject to the limits on occupational exposure
mentioned earlier and must complete a radiation safety training
course to be designated an authorized user. To verify that
occupational exposures do not exceed the regulatory limits,
authorized users may be monitored using personnel dosimeters. The
most common methods of personnel monitoring are
thermoluminescent dosimeter (TLD) badges and film badges.
Troxler recommends using TLD badges, since they can measure
both gamma and neutron radiation. Film badges are not suitable for
measuring neutrons.
In Canada, nuclear gauge users are not normally classified as
Atomic Radiation Workers. In such cases, the general public dose
limit of 0.5 rem per year would apply to nuclear gauge users. Users
may not be required to wear a dosimeter. To establish the personnel
monitoring requirements for your application, consult the conditions
of your radioactive materials license and the Canadian Nuclear
Safety Commission (CNSC) regulatory document R91, Monitoring
and Dose Recording for the Individual.
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