Internal exposure hazards - DOE-HDBK-1145-2001

Radiological Safety Training for Plutonium Facilities

DOEHDBK11452001

Instructor's Guide

4. Criticality

Show OT 18.

A criticality event can produce a life-

threatening dose of radiation to those who

are in the immediate vicinity.

Example: A burst of 1018 fissions in a metal

Discuss LD 50/30:

system may produce doses of 600 rad up to

Lethal dose at which 50% of

a distance of 30 feet and 100 rad up to

an irradiated population dies

around 70 feet (assuming there is no

within 30 days.

shielding). Also, there may be enough heat

generated to melt the system containing the

For humans, this dose is 450

plutonium. The fission products produced

rem, whole body.

will create residual contamination and

lasting radiation problems.

B. Internal exposure hazards

Plutonium is a heavy metal that is chemically

toxic as well as radioactive. Many other heavy

metals such as arsenic, lead, and uranium are also

chemically toxic.

Plutonium is primarily an alpha emitter and is

Alpha particles are thought to

particularly hazardous if taken into the body. Alpha

be approximately 20 times

particles do not travel far in material, which means

more damaging to tissue than

they lose all of their energy in a short distance.

beta particles.

Alpha particles cannot penetrate the dead layer of

skin on the body. However, when they are in direct

Show OT 19.

contact with our living cells, such as in our lungs,

they are a hazard. Other alpha emitters include

natural radon, which is also an inhalation concern.