Systems That Support Safety Functions

DOE-STD-6003-96

geologic burial. Sufficient holdup capacity should be provided for retention of gaseous and liquid

effluent containing radioactive materials, particularly where unfavorable site environmental con-

ditions can be expected to impose unusual operational limitations upon the release of such

effluent to the environment. The design should limit the release of radioactive materials in efflu-

ents and emissions to ALARA levels during normal operation. There should be no interconnec-

tions between liquid effluent streams such as streams containing radioactive and/or hazardous

waste, potable water streams, other incoming non-potable streams, and other outgoing streams.

Means for measuring the amount of radionuclides in effluents and emissions during nor-

mal operation and off-normal conditions should be provided. Means should be provided for mon-

itoring the fusion island components, fusion island building, and the site areas for radioactivity

that may be released from normal operations and off-normal events including design-basis

events. Alarms should be provided that will annunciate if radioactivity levels above specified

limits are detected in exhaust streams. Appropriate manual or automatic protective features that

prevent the uncontrolled release of radioactive material to the environment or workplace should

be provided. Systems designed to monitor the release of radioactive materials should have

means for calibration and testing their operability. Sampling and monitoring should ensure ade-

quate and accurate measurements under normal operations and off-normal events including

design-basis events. Monitoring systems should be calibrated annually at a minimum with

appropriate national standards to ensure validity of reported values. Radiation monitoring,

alarm, and warning systems that are required to function during a loss of normal power should

be provided with an emergency uninterruptable power supply (UPS) unless it is demonstrated

that they can tolerate a temporary loss of function without losing needed data, and they are

provided with standby or emergency (switched) power. Determination of the power supply type

and quality should be based on the safety classification of the monitoring system or device. In

addition to a local station alarm, radiation monitoring systems should have central (i.e., control

room or radiation monitoring office) readout and alarm panels that are accessible after design

off-normal event conditions to evaluate internal conditions.

6.4 Systems That Support Safety Functions

As noted in Section 6.1.2, SSCs required for the performance of a public safety function

should be designated as safety-class. This includes supporting systems such as power, I&C,

and cooling that directly support the system in the performance of the public safety function. In

a similar manner, systems directly supporting a safety-significant SSC should be classified as

safety-significant. Guidance for these support systems is given in Sections 6.4.16.4.4.

6.4.1 Instrument and Control Systems

I&C systems include equipment and components that monitor and display facility parame-

ters, indicate parameter value changes, actuate equipment to maintain the parameters within

specified limits, return the facility to operation within these limits, and mitigate conditions result-

ing from operation outside limits. Specific equipment includes sensors, signal transfer media,

signal processors, control circuits, and actuation devices.

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