Potential Safety Functions

DOE-HDBK-6004-99

Potential Safety Functions

The potential safety functions for confinement systems and their associated HVAC systems are:

1. Provide barriers against the release or spread of gaseous and particulate contamination during

normal and off-normal conditions (ASHRAE , ASHRAE 91 and DOE 6430.1A)

2. Provide the necessary ventilation system functional capabilities to control differential pressures

such that air flows from cleaner areas to potentially more contaminated areas during normal and

off-normal conditions. (ASHRAE 91)

3. Provide filters or other means to remove contaminants before exhausting to the environs.

4. Maintain the required ambient conditions within confinement, e.g. temperature, pressure,

humidity, and concentrations of radiological, toxic, corrosive or explosive substances, to protect

personnel and ensure the capability of personnel or equipment to perform safety functions.

(ASHRAE 91)

5. Provide the capability to isolate and control tritium or any other contaminant released within

confinement.

6. Provide instrumentation and/or testing and surveillance to monitor the condition and capabilities

of the confinement system, the ambient conditions within confinement, and the effluents from

confinement to the environs. Applicable items should be monitored during normal and off-normal

conditions as required to ensure and verify safety function. In addition potential airborne

contaminants or corrosive agents that may compromise the ability of personnel or equipment to

perform safety functions should be monitored and controlled. (ASHRAE 91, DOE 5480.11 and

DOE 6430.1A)

Safety-Related Design Guidance

System Boundary

The confinement/HVAC system boundary is defined for each confinement barrier and includes the

contiguous structural barrier and its associated ventilation and filtration equipment.

Structural Design

Design basis loads are derived from the internal and external events identified as the PIE (Postulated

Initiating Events) in the safety analysis. Loads and the combinations thereof should envelope loads

considered in structures per ASCE 93.

The methods of analysis depend on the performance category and loads being considered. Some of

the methods are described in ASCE 80. Elastic system analysis methods may be adequate for lower

performance categories whereas for higher performance categories inelastic analysis methods may

be required. Guidelines to seismic analysis are available in DOD 86. Dynamic seismic structural

analysis may be performed for predicted ground motions based on geotechnical site specific