Electrical Power Systems

DOE-STD-6003-96

n. Safety-class and safety-significant equipment should be designed to fail safe on loss

of motive force or power. In addition, safety-class equipment should be designed to

meet single failure criteria.

o. If required by the safety analysis, safety function actuation should be sealed in so that

the safety function actuation is maintained even if the logic that initiates the actuation

is lost. Controlled bypasses may be provided for operator interruption or adjustment of

automatic actions.

6.4.2 Electrical Power Systems

The electrical power system includes on-site alternating current (ac)/direct current (dc)

sources and distribution networks and feeders(s) from the off-site grid. The switchyard is the

interface between the off-site grid and the fusion facility. From the switchyard, the electrical

power distribution system divides into two main parts: the fusion facility system and the balance-

of-plant system.

The fusion facility distribution system supplies the heavy (and often pulsed) loads for

fusion facility operation, including the magnet power supplies and various plasma-fueling and

heating power supplies. The system may provide for safety-class loads in addition to non-safety-

class loads, in accordance with the facility safety analysis. An emergency generator or UPS or

both should provide power for safety-class loads in the event of loss of off-site supply.

Additional design guidance specific to the electrical system is provided.

a. Safety-class electrical systems

If the facility safety analysis concludes that safety-class electrical systems are necessary,

design of these electrical systems should comply with IEEE Standards 308 (IEEE 1980), 379

(IEEE 1988), 384 (IEEE 1992) and 603 (IEEE 1991).

The safety-class systems should be testable in compliance with the following standards:

1. ac systems and components--IEEE Standards 308 (IEEE 1980) and 338 (IEEE

1993),

2. dc systems and components--IEEE Standards 308 (IEEE 1980) and 338 (IEEE

1993).

b. Radiation/contamination and equipment life

Safety-class electrical equipment required to be in areas of radiation and contamination

should comply with IEEE Standard 323 (IEEE 1983).

c. Instrument and Control Systems

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