PARTICAL-SIZE DISTRIBUTION IN CAPACITOR DISCHARGE VAPORIZATION OF URANIUM DIOXIDE.

The release of radioactive aerosol particles as a results of an energy excursion during a hypothetical core disruptive accident (HCDA) in a liquid-metal fast breeder reactor (LMFBR) poses a potential radiological hazard. Primary aerosol particles in the submicrometre size range are of particular concern because they can remain airborne for long periods of time after an HCDA, even after agglomerating into groups of particles. A homogeneous nucleation-condensation growth model was developed for calculating particle-size distributions measured in capacitor discharge vaporization (CDV) experiments vaporized in an argon environment by rapid energy deposition through capacitor discharge. This was followed by rapid expansion and subsequent condensation of the UO//2 vapor. Measured primary particle-size distributions of the resulting aerosols were lognormal, with a geometric mean particle diameter of (0. 014 plus or minus 0. 002) mu m and a geometric standard deviation of 1. 7 plus or minus 0. 1.