Safety Policies and Controls - doe-hdbk-1113-98_reaffirm_2005

DOE-HDBK-1113-98

Radiological Safety Training for Uranium Facilities

Module 105 - Criticality Safety

Safety Policies and Controls

Achieving criticality involves bringing together many factors that promote a

sustained nuclear chain reaction. To avoid criticality, one should be aware of the

conditions that would promote a criticality for the particular materials they

encounter, and avoid those conditions that promote criticality.

1. General Criticality Safety Principles

Some things done to promote criticality safety include:

analyzing work environments to assess the risk of criticality and eliminate

likely criticality concerns;

using carefully planned and approved procedures;

providing specific training for those personnel working in areas where

fissile materials are present; and

implementing system design features that are favorable to criticality safety.

These features include:

using containers with a size and geometry that will not allow criticality,

designing piping systems to prevent buildup of uranium and prevent

criticality,

using materials known as poisons to absorb neutrons and prevent them

from being absorbed by the uranium atoms,

controlling material that surrounds containers or systems containing

uranium, and

controlling uranium inventories.