Design Basis Accidents

DOE-HDBK-6004-99

2. Transfer the combined heat load to a safety-class heat sink. For shutdown conditions, to the

extent practical, transfer of heat to a heat sink should be passive and require no human

intervention.

3. Partially confine radioactivity entrained or deposited in the coolant system, and provide for

suitable releases to environment or transfer to a waste facility.

4. Collect coolant drained from the coolant system in preparation for maintenance.

5. Provide makeup coolant for small breaks, leaks or draining required for maintenance activities

in the cooling system pressure boundary.

Design Basis Accidents

The safety analysis should specify design basis accidents. Cooling systems design should implement

the applicable safety functions credited in the safety analysis for design basis accidents. A typical

frequency for design basis accidents is greater than 10-6/year. The safety analysis should specify the

actual frequency. The following are potential design basis accidents for the cooling systems of fusion

devices:

Internal Initiators

1. Cooling leak within vacuum vessel

2. In-Cryostat tube leak

3. Out-of-Cryostat leak

4. Loss of coolant pumping

5. Low of coolant flow

6. Loss of heat sink

7. Missile or pipe whip

8. Increase in fusion power

9. Human Error

External Initiators

1. Natural phenomena, including earthquake, tornado, hurricane, seiche, tsunami, etc.

2. Fires

3. Aircraft or other missile impact (excluding sabotage).