Potential Vacuum Hazards and Proposed Solutions for Personnel Safety during an Air Ingress Accident in ITER

This paper discusses the possible forms of injury to maintenance personnel that could arise from a cryostat air ingress event. The results of a thermal-hydraulic analysis of several cryostat breach sizes show the time scales for possible injury and the severity of air pressure transients in the rooms near the cryostat. Energy sources were reviewed to identify worker safety concerns in a cryostat vacuum breach event. The room air pressure drop in medium and large breaches is the most important worker safety concern. Standard vacuum safety techniques are reducing time in proximity, maintaining an exclusion area, and employing some form of barrier or shielding between workers and vacuum reservoirs. Other suggested safety techniques discussed here are engineering controls (doors that can be easily opened under differential pressure), and administrative controls (buddy system, evacuation plan). These techniques are easy to implement in early design stages.