Safety-Class Design Criteria and Standards

DOE-HDBK-6004-99

2) Fire.

3) Human errors.

b) External Initiators:

1) Natural phenomena including earthquakes, hurricanes, tornadoes, floods, etc.

2) Aircraft and other missile impact.

3. Beyond Design Basis Accidents:

There are no system safety functions required for beyond design basis accidents.

Beyond design basis accidents include internal and external initiators whose frequency is lower

than the design basis frequency limit specified in the safety analysis.

Safety-Class Design Criteria and Standards

General Design Safety Features

Electric power from the transmission grid to the on-site electrical distribution system should be

supplied by two physically independent circuits designed and located so as to minimize, to the extent

practical, the likelihood of their simultaneous failure under operating and postulated accident and

environmental conditions.

If safe shutdown equipment is identified as a safety function, two completely independent sets of

shutdown equipment should be provided. Each of the two sets of equipment should be capable of

safely shutting down the fusion facility independently of the other set of equipment. Each set of

equipment is referred to as a train of safety-class equipment, and is identified as Train "A" and Train

"B." Both trains "A" and "B" are completely redundant and independent of each other.

The on-site source of electrical power for each train is usually provided by safety-class diesel

generator set, one for Train "A" and one for Train "B," completely independent of each other with

no inter-connections between the two. Alternate methods of comparable reliability are acceptable.

General Design Criteria/Standards

1. Safety-class design criteria for protection against fire, natural phenomena: Structures, systems,

and components of safety-class electrical systems/components should be designed to be capable of

withstanding the effects of natural phenomena such as earthquakes, tornadoes, hurricanes, and floods

as established in fusion facility safety analysis, without loss of capability to perform their safety

functions.

The design should minimize the possibility and the consequence of fire and its effects on the electrical

safety-class equipment and devices.

The design should prescribe the use of fire resistant materials to the maximum practical extent

possible for all equipment to be used for the safety-class functions. The design should provide for

fire detection and suppression systems having appropriate capacity and capability to minimize adverse