Introduction - DOE-HDBK-1141-2001

Radiological Assessor Training

DOE-HDBK-1141-2001

Student's Guide

Introduction

The guidance in DOE-STD-1136-2000, Guide of

Good Practices for Occupational Radiological

Protection in Uranium Facilities, should be reviewed

in detail prior to conducting an assessment of

uranium facilities. The following is a brief overview

of the radiological aspects of uranium.

II.

Radiological aspects of uranium

A. Radiological properties of uranium

Fifteen radioisotopes exist, but the three of most

concern to the uranium industry are:

Uranium-238:

99.7% abundant in natural uranium;

half-life = 4.5 billion yrs,

specific activity = 3.3 E-7 Ci/g

Uranium-235:

0.72% abundant;

half-life = 710 million yrs,

specific activity = 2.1 E-6 Ci/g

Uranium-234:

0.006% abundant;

half-life = 247 thousand yrs,

specific activity = 6.2 E-3 Ci/g

Enriched uranium has a higher content of

Uranium-235 than found in nature. Typical

enrichment values are:

2%-3% Uranium-235: power reactor grade

fuel

>90% Uranium-235: weapons grade material

Module 6 - 1