Re: Procedures for detecting and characterising hot particles

[Mike Lantz <mlantz33@CYBERTRAILS.COM>]

Monty,



I see that you received text which was from San Onofre's training in the late 80's and early 90's.  I was the industry representative for NCRP 130.

We've spoke a few times.  I just wanted to comment that if you review only what has been published, you would think that the vast majority of

particles encountered by workers would be ..............................Fuel.  However, this is far from true.  Having been deeply involved in hot

particle detection since 1986 and having been to about 40 nuclear facilities in the US, I would say that the particle-people encounters are comprised

of the following mix:



90%         Co-60

  9%         Fuel (old and new)

  1%         various (inconel, ruthenium, antimony, Zr/Nb)



I am very confident in these numbers.



As far as detection goes, it is simple.  There are no easy ways.  You smear and look.  You survey directly.  You monitor people.  There are failure

modes.   You must rely on many beta detecting monitors like PCMs, LCM's and friskers.  Since the vast majority of particles are the low energy betas

from Co-60, they will not see the betas if the particle is even barely covered (cloth, shoes).  They must rely on the gamma efficiency which is

one-tenth of the beta efficiency.  Better to back up that monitoring with large gamma scintillators.  Combined, they detect both types of particles:

beta for the high energy fuels and gamma for the Co-60.



I've rambled, but thought you might need these thoughts.



Mike Lantz



MW Charles wrote:



> Dear Colleagues

>

> Hot particles (physically small radioactive sources) are a common

> problem on nuclear reactors and reprocessing facilities.  As far as I

> know there is no standard national or international protocol which

> describes the most appropriate methods for their detection and

> characterisation (chemical and radioactive composition, activity,

> size, mass, etc).  I recall some years ago coming across American

> reports which went some way towards this.  Please can anyone

> direct me to appropriate literature or individuals who may be able to

> help.

>

> Many thanks

>

> Monty Charles

>

> ***********************

> Dr Monty Charles, Reader in Radiation Physics

> Radiation Biophysics Group

> School of Physics & Astronomy

> University of Birmingham

> Edgbaston

> Birmingham B15 2TT

> England

> TEL +44  0121 414 3483

> FAX +44  0121 414 4725

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