Observation of the Behaviour of Confined PBX 9501 Following a Simulated Cookoff Ignition

The response of small confined disks of PBX 9501 to cookoff has been investigated with high-speed photography through a transparent toughened-glass window, observing both the ignition and propagation of reaction. External strain gauges and microwave interferometry have been used to measure the expansion of the confining ring. The results show that when reaction starts, cracks propagate from the ignition site and that these cracks may be effective in leading to the fast transfer of ignition to other sites within the charge.