Fragmentation of Respirable PuO2 Particles in Water by Alpha Decay - A Mode of “Dissolution”

Abstract

Fission fragment tracks from neutron activation have been used to observe the alpha-emission-induced fragmentation in water of monodisperse particles of 239PuO2 of 0.30 μm geometric diameter into subparticles containing 60–10,000 plutonium atoms. The measured size distribution can be described by a power law relation R = aNpPu−beta, where R is the relative number of subparticles containing NPu plutonium atoms and 3 > beta > 2. This relation is inferred to be valid over the range 1 ≤ NPu ≤ 104. Although the exact details of the mechanism of subparticle formation are not certain, recoiling uranium nuclei formed during alpha decay of plutanium atoms are implicated.