LLNL Chemical Reactivity Test (CRT) Compatibility Approaches

摘要

Testing and characterization of high explosives (HE) often requires assembling explosives with other materials, e.g. metals, adhesives, plastics, other explosives, etc. Whenever an explosive is put in contact with other materials, there is a risk that a chemical incompatibility will alter the stability of the explosive. In the worst-case scenario, the explosive may ignite and deflagrate or detonate resulting in personnel injuries or death and equipment damage. To avoid this scenario, all material-HE combinations are required to be tested for chemical compatibility via a simple screening test call the Chemical Reactivity Test (CRT). LLNL is continually evaluating our methods, guidelines, and criteria for analyzing thermally aged materials in contact so we can provide safe and accurate estimates of the explosives' compatibility where they are most applicable to LLNL operations. The standard CRT test involves thermally aging a material or mixture for 22 hours at 80 C or 120 C; the temperature choice is based on the materials thermal properties and application. Materials that are tested, and pass CRT testing have been deemed safe for storage or additional experimentation. With an accelerated aging period, our focus is to provide a rapid screening approach to estimate when the materials in contact would start to show signs of chemical reactivity or safety concerns. Although this screening process works well for high explosives, there are materials and mixtures we must be mindful of when using the CRT for safety concerns. Additional thermal testing can be performed on HE and/or combinations to concur and support compatibility results. DSC testing is sometimes necessary to use in conjunction with CRT to provide our requestors with accurate results.