IAEA SAFETY GUIDES - gnssn - International Atomic Energy Agency

This publication is no longer validPlease see http://www-ns.iaea.org/standards/FIG. 4. Particle size deposition probabilities fo r particles from nearly molecular dimensionsto those in the visible range. URT: upper respiratory tract. LRT: lower respiratory tract. Notethat the concept o f aerodynamic diameter does not apply to particle diameters o f 10~2 \m.and below.TABLE IV. THORON DECAY PRODUCTS AND THEIR PROPERTIESHistoricalnameIsotopicnameHalf-lifePrincipalradiationPrincipalalphaenergiesPrincipalgammaenergies(MeV)(MeV)Thoron Rn-220 55.6 s a 6.288 (100%)Thorium A Po-216 0.15 s a 6.8 (100%)Thorium B Pb-212 10.6 h P7 0.2386 (45%)Thorium C Bi-212 60.55 min a (36%) 6.051 (25%)6.090 (10%)13 (64%)Thorium C' Po-212 0.3 /is a 8.95 (100%)Thorium C " Tl-208 3.1 min 0 0.5108 (22%)0.5831 (86%)0.8604 (12%)2.615 (100%)Thorium D Pb-208 Stable12