Method for estimating the challenge to an air-cleaning system resulting from an accidental explosive event

A method is presented for determining the challenge to an air cleaning system resulting from an accidental explosion in a process cell of a fuel cycle facility. In many safety analyses, this quantity is estimated by multiplying the volume of the process cell by the maximum concentration of airborne material that is reasonably stable to agglomeration and sedimentation. Particle sizes are inferred from the assumption of concentration stability. The suggested method is based on extrapolation of data obtained for the explosive dispersal of chemical agents. Application of the extrapolated information to fuel cycle facilities results in an estimate of total material airborne as well as particle size distribution. An important variable is the weight ratio of inert material to that of explosive (mass ratio). As the mass ratio is expected to be high in fuel cycle facilities, the method predicts that airborne material will have size distributions that have relatively large mean values following which substantial settling will occur. An illustrative calculation that takes mass ratio and settling into account suggests that total filter challenge may be greater than previously estimated, but that the fraction of that challenge that is smaller than 10 micro-meters may be very low. For use in safety analyses, the method requires experimental validation of the extrapolation of reference data to the conditions existing in a fuel cycle facility.