Electrical Power - doe-std-1128-98

DOE-STD-1128-98

C.5.2

Electrical Power

Both normal and emergency power supplies should be available to a plutonium

facility to ensure that critical systems can continue to operate under both normal

and accident conditions.

C.5.2.1

Normal Power

A plutonium facility's normal electrical power needs should be met by

two primary feeders. The preferred primary feeder should provide basic

service to the facility and consist of a radial feeder connected directly to

the main substation serving the area. To minimize power outages, this

feeder should be an express feeder and should not have any other loads

connected to it.

The alternate primary feeder should be in ready standby to provide

backup power to the preferred primary feeder power supply. In the event

of a forced outage or planned maintenance of the preferred primary

feeder, the power load should automatically transfer to the alternate

feeder. The alternate primary feeder should also be a radial feeder

connected directly to a substation and should have no other loads

connected to it. To minimize simultaneous outages of the preferred and

alternate primary feeders due to lightning or other physical damage, the

two feeders should have maximum physical separation.

C.5.2.2

Emergency Power

The facility should be provided with a reliable, local source of

emergency power if both primary sources fail. The emergency power

source should be completely independent of the preferred and alternate

primary feeders. The emergency power should be generated onsite by

turbines or diesel generators with automatic starting and switch-over

equipment. The emergency system should be physically separated from

the normal power systems, except at the automatic transfer switch, so

that any electrical or mechanical breakdown of the normal power system

will not render the emergency system inoperative.

The time lag between electrical power failure and the resumption of

emergency power should not exceed 20 seconds, and the emergency

system should remain energized for at least 5 minutes after the

restoration of primary power to allow for an orderly transition. The

emergency power sources should have sufficient capacity and sufficient

fuel supplies stored onsite to maintain the integrity of all critical building

systems for approximately 48 hours. The amount of time that emergency

power is necessary should be determined by the requirements for

bringing the processes to safe shutdown condition. Chemical and thermal

inertia also should be considered. The emergency power system should

be able to carry identified critical loads such as air exhaust and supply

systems, fire-detection and fire-suppression systems, related

instrumentation and control functions, necessary criticality and radiation-

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