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Radiological Safety Training for Plutonium Facilities
DOEHDBK11452001
Instructor's Guide
Plutonium emits one or more of the following types
of radiation: alpha, beta, neutron, gamma, and x-ray.
The half-lives of nuclides range from 21 minutes for
Pu-233 to 80 million years for Pu-244.
Alpha radiation and low-energy (less than 70 keV)
beta radiation will not penetrate the dead layer of skin
and present no external hazard. These become
hazardous when they are introduced inside the body,
where they have direct contact with living cells.
With plutonium, neutron radiation is the most
penetrating and can be a significant biological hazard.
Most x-ray and/or gamma radiation from plutonium
is of lower energy, ranging from 17-20 keV, and is
moderately penetrating. This radiation becomes a
concern mostly with those handling the material.
There is an additional radiological problem with
Pu-241. It is impossible to separate plutonium
nuclides to 100% purity; there is always some Pu-241
present. The Pu-241 decays to americium 241
(Am-241). Am-241 emits a higher-energy gamma ray,
which is a concern. This americium "in growth" results
in increasing radiation levels for many years. This can
contribute to significant doses, since some
applications may have 30%-50% Pu-241.
D. Criticality
Discuss the criticality accident
While several plutonium nuclides can fission, only
at the Fuel Fabrication Plant in
Pu-239 is of practical importance as a criticality
Tokai-mura, Japan, September
concern. A criticality accident involves an uncontrolled
1999.
chain reaction that releases large quantities of heat,
neutrons, and gamma radiation. It does not create an
Refer students to LL 5.
atomic explosion. Facilities that possess fissile
material have criticality detection systems to warn
workers of an event. Remember, if a criticality
accident does occur, exit as quickly and safely as
possible. JUST GET OUT!
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