Small-scale explosives sensitivity saftey testing: A departure from Bruceton

In order to safely work with explosives, their sensitivity to external stimuli needs to be characterized. The Bruceton method for evaluating explosives sensitivity results has been used effectively for over six decades. This has included the skid test on the large scale, and the friction and drop weight impact tests on the small scale. The result was a 50% probability of reaction, useful for ranking the comparative responses of various explosives in order to make a practical assessment of handling safety. This paper summarizes the limitations of the Bruceton method and introduces the efficacies of the D-optimal test method. A comparison of the two approaches is provided using results for RDX, HMX, and PETN. For this paper, the Los Alamos Type 12 Drop Weight Impact apparatus is used to generate and compare 50% drop heights (H50), or mean probability of reaction, using the Bruceton and D-optimal methods. The results show that the mean obtained by the D-optimal method is not significantly different from the mean obtained by the Bruceton method, alleviating potential concerns about departing from a historical database. The D-optimal method accomplishes this by using a larger step size between consecutive tests to efficiently converge on the 17% and 83% probability points of the distribution. In the presentation we will also discuss details of our historical Bruceton testing for impact and friction sensitivity and how these tests are currently evolving in our facilities.