UNCERTAINTY QUANTIFICATION OF DIMP PYROLYSIS KINETICS

To develop effective explosives and strategies for the rapid destruction of sarin stockpiles, a reliable understanding of sarin’s chemical kinetics is needed. Kinetic mechanisms of sarin simulants such as di-isopropyl methyl phosphonate (DIMP) are developed instead because they have a similar chemical structure as sarin and are less toxic. A detailed DIMP kinetics mechanism has been developed in the past; however, there is a considerable amount of uncertainty surrounding it. This uncertainty manifests through the choice of pathways, and their respective reaction rates, leading to large variations in outcomes predicted through simulations. Out of the many reaction pathways involved in the decomposition of DIMP, the initiating steps are the most crucial. Out of the two possible initiating pathways in the destruction of DIMP, the lower activation energy pathway is dominant for all temperatures. The purpose of this study is to investigate the uncertainties associated with the dominant initiating pathways of the DIMP kinetics mechanism. Propagating rate parameter uncertainties of the dominant pathway through computational models yields large uncertainties in predicting DIMP survivability at different temperatures. The prediction uncertainties are larger at lower temperatures than at high temperatures. This can significantly impact the ability to precisely predict collateral damage caused by partially destroyed DIMP in the far-field of an explosion. After reducing these rate parameter uncertainties, using Bayesian inference, the prediction uncertainties were within reasonable limits. The results here provide a reduced subspace for uncertainties associated with the first and most important step in the breakdown of DIMP, which shall enable more reliable predictions.M.S