A Simple Method to Estimate Airborne Release Fractions Associated With the Pressurized Release of Radioactive Materials

Abstract

Abstract Pressurized release of radioactive materials, such as plutonium bearing oxides, could occur during a fire accident event where a robust container holding the radioactive materials ruptures catastrophically due to excessive pressurization. The common source of pressurization is the vaporization of water adsorbed onto the plutonium bearing oxides. A simplified pressure based approach derived from NUREG/CR-6410 is presented which allows calculation of airborne release fractions for pressures up to and above 500 psig. A parametric study is used to determine a bias (conservative or non-conservative) when the approach is applied to DOE-STD-3013 welded stainless steel containers which are used to store plutonium bearing oxides at the US Department of Energy Savannah River Site. The event considered is a 3013 container subjected to a hypothesized facility fire where the container fails catastrophically and ruptures resulting in a vented high pressure release of the plutonium bearing oxide materials. The parametric study shows that the simple correlation for calculating airborne release fractions is biased high by about 40% compared with the detailed NUREG/CR-6410 method. Care should be taken in using the simplified approach where the ratio of vessel net free volume to maximum allowed oxide mass is greater than 0.66 cc/g.