General Considerations

DOE-HDBK-1132-99

The specifics of confinement system design, as they relate to a particular

facility, should be guided by an iterative process between safety analyses and

design. Safety analyses define the functional requirements of the design, such

as the type and severity of accident conditions that the confinement system

must accommodate. The design should also consider sources of functional

design requirements including maintenance, operability, and process

requirements. This section discusses primary, secondary, and tertiary

confinement systems, design of confinement ventilation systems, and aspects

of confinement system design by nuclear facility type. The American Society of

Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) HVAC

Applications Handbook provides general information regarding heating,

ventilation, and air conditioning (HVAC) design for confinement systems.

General Considerations. Confinement system features, including confinement

1.1.2

barriers and associated ventilation systems, are used to maintain controlled,

continuous airflow from the environment into the confinement building, and then

from uncontaminated areas of the building to potentially contaminated areas,

and then to normally contaminated areas.

For a specific nuclear facility, the number and arrangement of confinement

barriers and their design features and characteristics are determined on a case-

by-case basis. Typical factors that affect confinement system design are the

type, quantity, form, and conditions for dispersing the hazardous material,

including the type and severity of potential accidents. In addition, alternative

process and facility design features may reduce potential hazards and the

resulting requirements for confinement system design. Engineering evaluations,

trade-offs, and experience are used to develop a practical design that achieves

confinement system objectives.

Because the number and arrangement of confinement systems required for a

specific nuclear facility design cannot be predicted, this discussion describes a

conservative confinement system design that uses the three principal

confinement systems described below. The discussion assumes that three

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