Marco Kaltofen, Nuclear Science and Engineering , presented at Worcester Polytechnic Institute, March 19, 2014: High Radioactivity Particles in Japanese House Dusts… The Fukushima Dai‐ichi accident released very high activity inhalable dust particles that travelled long distances… Airborne dusts can transport radioactive materials as isolated individual particles containing high concentrations of radioisotopes. Alpha and beta emissions related to fission wastes and dispersed fuel particles are hazardous when inhaled or ingested. Radioactively‐contaminated environmental dusts can accumulate in indoor spaces, potentially causing significant radiation exposures to humans via inhalation, dermal contact, and ingestion… a micron‐scaled particle [had] activity greater than 1.0 PBq kg [1 Quadrillion Bq/kg]. The par6cle was collected from a home in Nagoya, Japan. Nagoya is 460 km from the accident site… It contained both fission products and decay products of 238U… tellurium up to 48.0 %, cesium up to 15.6 %, rubidium up to 1.22 %, polonium up to 1.19 %, dysprosium up to 0.18 %, as well as trace amounts of Sn, lead, nickel, iron, and chromium… 226Ra, 134Cs, and 137Cs, 241Am, and 230Th [were] the most commonly detected gamma photon-emitting isotopes… about 25 % of dusts sampled [were] autoradiographically positive for hot particles… the majority of these hot particles were 10 um [micrometers] or less in size, meaning that they were potentially inhalable… Radioactively‐hot particles on the respirable size range were routinely detected, with one as far as 460 km [285 miles] from the release site.
Kaltofen : Radioisotopes in dusts released by Fukushima Daiichi units [include] Uranium and plutonium fuels and transuranics such as americium and neptunium… individual radioactive particles [in an] Ibaraki dust sample [include] Eu, Y, Zr, Th, Ce, Sr… in 1 to 15 um size range…
Kaltofen : The Japanese samples came from as far north as Sapporo in Hokkaido Prefecture and as far south as Tokyo, a range of 780 km. Fifty nine samples of dust from Japan were analyzed… Radioisotopes specific to the Fukushima Daiichi accidents, including Cs134, Cs137, and Co60 were detected in dust samples taken throughout Northern Japan, including areas more than 200 km outside of the accident exclusion zone. Cs134 was detected at all of the Japanese sites tested… Japanese samples… analyzed in the first month after the accident also contained I131 and Am241… Radioactive dust has become a ubiquitous part of life in northern Japan.
Chris Harris, former licensed Senior Reactor Operator & engineer, Aug 21, 2014 (at 24:00 in): NHK just [broadcasted] that many studies are showing… that multiple cores — parts of it, or some, or even most of it — had been ejected. We thought that too. Once you breach containment, that was one of my big concerns — where did the core go after an explosion like? Whether it be steam or hydrogen explosion or a combination of both… it got ‘sneezed out’ all over the place. It’s totally – it’s a huge mess.