Radioactive Properties - hdbk1113cn10046

DOE-HDBK-1113-98

Module 101 Properties of Uranium

Lesson Plan

Instructor's Notes

becoming inert helium gas. The amount is only

significant for high specific activity forms of

uranium. For exampl e, a sampl e of 99% u ranium-

233 (233U) with 1% 232U creates approximately its

own volume of helium gas every year. Sealed

containers must include adequate gas space or be

fitted with pressure release valves. Once the

pressure is relieved, the low-pressure helium gas is

harmless.

Hydrogen gas is generated from uranium in water,

and this may also produce a pressure buildup

situation. Because the hydrogen buildup may also

be a fire hazard, it is discussed later in this module

in the Chemical Properties section.

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Radioactive Properties

Uranium in its pure metal form is a silvery, gray metal and

is the heaviest naturally occurring element. There are 18

separate isotopes of uranium. Isotopes are elements that

have the same number of protons, but different numbers of

neutrons. For example, 235U has 92 protons with 143

neutrons and 238U has 92 protons with 146 neutrons.

Uranium is radioactive. Partially because of its size, the

nucleus of a ur anium atom is unst able. It reduces its size

either by alpha particle emission or by nuclear fission, in

which the uranium nucleus splits, pri marily, into two

smaller fiss ion products . Both process es release e nergy,