Localized Instantaneous Dose Rates from Inhaled Particles of 239 Pu

In this work, the authors present instantaneous local dose rates from particles of plutonium-239 oxide ( 239 PuO) embedded in various regions of the respiratory tract. For comparison, a small number of simulations were performed in a representative region of the respiratory tract with other chemical compounds including pure metallic 239 Pu, 239 PuO 2 , 239 PuO 3 , 239 Pu 2 O 3 , and 239 Pu(NO 3 ) 4 . A small number of simulations were also performed with 238 PuO, weapons grade Pu, and Pu from a typical radioisotope thermoelectric generator (RTG) source for the same reason. The self-shielding effect is minor for very small particles but gradually becomes more significant as the particle size increases. For particles that are 0.1 μm and larger (excluding Pu nitrate), the calculated dose rate within several microns of the particle may be sufficient to damage lung cells, but the implications of damage to such a small volume of tissue are unclear. However, it is reasonable to assume that clinical effects will be observed if a large enough volume of tissue is damaged, as might happen when large numbers of particles are inhaled. The instantaneous dose rate around a particle may be predictive of deterministic effects, scar tissue formation, and biokinetics.