[ RadSafe ] Fukushima Hot Particles

Matt sargent matts at irss.ca
Wed Jun 29 11:23:31 CDT 2011

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

From: Matt Sargent [mailto:Matt at buffaloinspection.com] 
Sent: Wednesday, June 22, 2011 12:54 PM
To: Drolet, Marc
Subject: Thanks 

Thanks for the link, I appreciate the fast response.  So is there an
accurate way to count the hot particles?  For example you have Arnie
Gundersen and others talking about the amount of particles being inhaled in
Japan Fukushima around 11 a day and Seattle around 5 a day.  Is this
accurate?  Even though very little radiation is being detected what is the
possibility that it is being created by hot particles?   It’s a very
different situation if you are breathing the particles in rather than just
absorbing the radiation/energy through the skin.  As I am sure you are
aware.  I am just trying to understand the situation there is some many
different explanations and opinions on it.  

Dose the Nuclear Regulatory Commission of the USA have a similar setup for
monitoring radiation readings?  I understand that the jet stream has
sheltered us for the most part while the majority has gone down to our
southern neighbors.    I have talked to associates that claim at times
upward of 30 x normal background.  Is there any where that you know of to
monitor the readings in the USA?  

Thanks for your time.  

Matt Sargent

Matt Sargent
Safety Compliance Officer
matt at buffaloinspection.com
Office # 780-486-7344
Fax # 780-486-4685

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-----Original Message-----
From: Peter Bossew [mailto:Peter.Bossew at reflex.at] 
Sent: June 28, 2011 2:06 PM
To: radsafe at health.phys.iit.edu
Subject: [ RadSafe ] Fukushima Hot Particles


Only now I noticed the 'hot particles' thread. I apologize if I missed
something, and if I am repeating arguments.

The only evidence for hot particles is 

(1) an autoradiography of an airfilter;
(2) an electron microscope picture of an isolated particle.
(3) XRF scan of the particle.
(4) gamma and alpha spcs  of the bare HP. Also easily done (I did it with
Chernobyl HPs.) The r.n. composition is very different from the continuous
phase on the filter.

This is all done quite easily by standard techniques.

Does anybody know about such findings? Please let me know any reference.
(I haven't seen any.)

A gamma spectrum of an air filter is no evidence. A NaI spectrum is just
ridiculous for this purpose.
The argument that Rn progenies attached to aerosols can appear as HPs is
wrong. After a few hours 214Pb,Bi have decayed.  210Pb,Po are usually not
present in enough activity, same for Tn. Btw. it can easily be checked by
investigating BG filters, and if such suspected particle is found, perform
g & a-spc on the isolated particle. Rn and Tn progenies are very easy to
identify (should be a triviality in this forum.)

Generally speaking, the release conditions were such that there is a
chance of HPs. Therefore experimental evidence would be valuable
contribution to understanding the accident.


Peter Bossew

(German Federal Radioprotection Authority, Berlin)

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