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

DOE-HDBK-1113-98

Module 105 Criticality Safety

Lesson Plan

Instructor's Notes

D. 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.