Gas

DOE-HDBK-1113-98

Module 101 Properties of Uranium

Lesson Plan

Instructor's Notes

inhaled and a bsorbed into the bloodstr eam through

the lungs.

Provide a facility specific

Gas

example of uranium in gaseous

form.

Another form of uranium that is an inhalation

hazard is the volatile UF6, becoming a gas above

56C. However, most uranium daughters are not

volatile, an d so can accumula te in storage

cylinders. When the volatile UF 6 is extracted, the

nonvolatile daughters remain in the cylinder,

resulting in the buildup of residual radioactivity.

However, in the case of uranium-232 (232U),

uranium-235 (235U), and uranium-238 (238U), each

of these uranium isotopes has a radon daughter.

Radon is a gas at all but very low temperatures;

therefore, if the radon escapes, the subsequent

daughters can accumulate in closed or poorly

ventilated areas.

In some situations, pressure from volatilized UF 6

gas can build up in small volumes such as a sealed

container or a pipe run between two valves. Line

breaks and leaks will cause a release of th e UF6.

As the escaping UF6 gas cools, it becomes

particulate, which may have a suffocating effect on

any nearby workers.

Another reason for pressure buildup is alpha

particles emitted in radioactive decay eventually