[ RadSafe ] Fukushima Hot Particles

Steven Dapra sjd at swcp.com
Wed Jun 29 18:48:17 CDT 2011

June 29

         Thank you for posting this very informative article about 
hot particles.

Steven Dapra

At 10:23 AM 6/29/2011, you wrote:
>Thought I Would share this email I have received regarding questions to my
>regulatory authority, regarding the hot particles.
>Matt Sargent
>Safety / Compliance Officer
>matt at buffaloinspection.com
>Office # 780-486-7344
>Fax # 780-486-4685
>Matt: here's from one of our specialists.
>Good Afternoon,
>You had raised some questions about hot particles and their association with
>the Fukushima events.  NCRP Report No. 130- Biological Effects and Exposure
>Limits for Hot Particles- is a good source of reference information about
>hot particles, including their detection.
>Hot particles have typically been associated with nuclear reactors and
>weapons testing and are usually beta emitting or gamma/beta emitting
>radionuclides, commonly Co-60 and other fission fragments. NCRP report No.
>130 defines hot particles as being greater than 10 microns and less than
>3000 microns. Hot particles are loosely defined as "high activity"
>particles.  They are often electrically charged and are water insoluble. Hot
>particles are typically found on the skin, and therefore much attention has
>been given to the effects on the skin and on the skin dosimetry related to
>hot particles.
>Hot particles have been  observed in association with the Chernobyl
>accident. The associated long distance transit with the large fire and
>explosions essentially caused a ballistic launch through the upper
>troposphere; not the usual mechanism of long range transit.
>Fukushima's primary containment was largely left intact; the releases were
>very different than with Chernobyl as they were mainly volatile in nature.
>It is unlikely that hot particles will be observed as a result of Fukushima
>especially in North America. However, in the coming months and years ahead,
>much work will be done in relation to Fukushima at which time more
>information will be available.
>Health Canada's network has observed volatile materials like Cesium, iodine
>etc. at stations outside of Japan and nothing that has looked like a piece
>of refractory material.  In a few months, Health Canada may do some
>autoradiograghy on some Canadian filters to look at activity distribution of
>longer lived materials.
>The reports which were linked in your e-mail (Fairwinds) make several claims
>of hot particles being breathed in every day and makes specific claims of 5
>hot particles/day being "breathed in" in Seattle. We have not found any
>credible information which supports this claim.
>It is notable that in NCRP Report No. 130 it is stated that there have been
>no reported clinically observable human injuries due to hot particle
>exposures in the workplace.
>I Hope this helps.
>Melanie Rickard
>External Dosimetry Specialist


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