Table - hdbk1113cn10118

DOE-HDBK-1113-98

Radiological Safety Training for Uranium Facilities

Module 101 - Properties of Uranium

HALF-

NAT.

ISOTOPE

IMPORTANCE

LIFE

ABUND.

An unwanted byprodu ct of 233U

production in a breeder reactor. Due

232

to its much shorter half-life, 232U

70 y

contributes most of the radioactivity

in samples of 233U.

Manufactured by irrad iating 232Th

233

1.6 x 10 5 y

with neutrons. It is a criticality

hazard because it is fissile.

238

U. It is

A decay product of

concentrated with 235U during

enrichment. Highly enriched uranium

234

2.5 x 105 y

0.0055%

contains about 1% 234U. Most of the

radioactivity of enriched uranium is

from the 234U.

Fissile with slow neutrons; therefore,

it is of primary interest for reactors

7.1 x 108 y

235

and weap ons. If not ha ndled safely,

~0.7%

235

an accumulation of

U could

become critical.

Some 235U is converted to 236U in

236

2.3 x 107 y

reactors. It is also present in

reprocessed reactor fuel.

The most abundant uranium isotope.

It is fissionable with fast neutrons;

238

4.5 x 109 y

~99.3%

however, it is not fissile (i.e., with

thermal neutrons) so it is not a

criticality hazard.

As uranium goes through radioactive decay, it produces other radioactive elements known as

radioactive decay products (also called progeny or daughter products). These radioactive decay

products are also radioactive and have to be taken into account for radiological protection purposes.