The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) has approved the first variance from the American Table of Distances (ATD) based on a quantitative risk assessment (QRA) compared to a tolerable level of risk. The Institute of Makers of Explosives Safety Analysis for Risk (IMESAFR) tool was used to conduct the quantitative risk assessment. ATF has issued eleven IMESAFR-based variances in the past, but this is the first time the agency has not used their problematic risk-bank methodology, but instead referenced acceptable risk criteria used by many government bodies globally, including the U.S. Department of Defense. IME Member Company, Nelson Brothers, was granted this landmark variance in April 2019.
IMESAFR is a quantitative risk assessment software that calculates risk to persons from explosives facilities. IMESAFR supplements the American Table of Distances, which was developed by IME a century ago, by incorporating donor structure and activity, the structure of exposed sites, and duration of exposed personnel to determine a level of safety. IME applauds ATF for their acceptance of the IMESAFR quantitative risk assessment tool as a valid method for evaluating risk from explosives storage magazines to persons within inhabited buildings and in vehicles on highways and for considering a tolerable risk criterion in this evaluation. IME also congratulates Nelson Brothers for receiving yet another historic variance.