Design of tunnel features for adit debris hazards mitigation in underground ammunition storage

For underground ammunition storage in rock caverns, the safety distances for debris resulting from an accidental explosion are generally very large. This is because most existing safety codes have been developed based on storage or tests sites where the exploding chamber is connected by a relatively short tunnel to the exit. This layout is referred to as a shot-gun layout. While some codes have indicated certain tunnel features for the mitigation of debris hazards, no quantitative guidelines on the effectiveness of such features exist. Recent studies and tests have demonstrated the effectiveness of several debris hazard mitigating measures such as long tunnels, sharp turns, debris traps, expansion chambers, and portal barricade. Based on a literature review and results from large-scale tests, this paper presents some quantitative guidelines on the design of debris mitigating features in underground storage.