Passive Systems

DOE-HDBK-6004-99

Passive Systems

For shutdown conditions, the cooling system design should incorporate passive features to the extent

practical for heat removal, transfer and rejection functions. The design objective should be to provide

adequate cooling of all safety-class structures, systems and components without human intervention

for as long a period as practical following shutdown of the fusion device.

Design Considerations

Cooling system structures, systems and components should be designed, fabricated, constructed and

tested to the highest quality standards practical.

Cooling system design should provide defense in depth through multiple confinement barriers and

redundant or diverse critical components or systems.

Unavailability of the onsite electrical power supply or the offsite power supply should be a

consideration in assuring cooling system functions, assuming a single failure within the cooling

system. Coincident failure of offsite and onsite power systems should not be a design consideration.

Cooling system design should consider the thermal, hydraulic and mechanical effects of unintended

operation of active components such as valves and pump motors.

Cooling system design should consider the thermal, hydraulic and contamination effects of cross leaks

between adjacent systems, such as the primary and secondary sides of heat exchanger.

Materials properties for cooling systems should include the effects of radiation embrittlement at all

levels of service temperatures.

Coolant system pumping should provide for coolant flow coastdown to prevent exceeding design

limits for safety-class structures, systems and components.

Discharge of coolant for pressure relief should be to a confinement tank that maintains the

confinement function of the coolant system.

The coolant system should include protection for overpressure to prevent degradation of safety

function.

The coolant system should include provisions for sampling for analysis of coolant properties and to

identify entrained radioactivity or other contaminants.

The coolant system design should minimize the number of interfaces between safety-class systems

and non-safety-class systems.

Coolant system design should include provisions for maintenance and radiation protection.

Cooling system design should include features to facilitate decontamination and decommissioning at

the end of service life.