Re: Technical basis for 100 cm^2, one more

[Schoenhofer <schoenho@via.at>]

Hi,

I followed the discussion now for a long time. I checked today a catalogue
of contamination monitors of an American company and found a probe with 100
cm2 surface......

I am very well aware of the confusion which different units may cause.
During and a few years after the Chernobyl accident, we had in my country
still the "curies" as an official unit, because our legislation was too slow
to introduce the new SI units also in radiation protection matters. All
other European countries had already introduced the SI unit Bq. The former
Sovjet Union still used the curies. We gave contamination as nCi per m2, the
Sovjet Union gave it as Ci per km2, the other European countries gave it as
Bq per m2. Our limits were set as nCi per kg or l, the European Union set it
as Bq per kg or l. Whether SI units make sense or not, but they should be
used to have common units for all measurements, to make them easily
comparable. I know from my many visits in the USA about the problems you
Americans face. I remember the confusion in the mass media that different
units created. 

In the meantime we have legislation which makes the use of SI units
compulsary. Any contamination has to be given as Bq per cm2 (or m2?)
Whatever is practical or has been done for a long time - it is not
conforming to legislation if one does not use the SI units. I know the units
of the USA and what I wonder most regarding the debate is that you use
cm2!!!!! whether it is 100 or 1. I would have expected square inches. I
simply cannot believe that there are no regulations in the USA regarding
contamination and how the results should be presented.

I want to finish with a scientific view: We had recently a case of
contamination of a person with Sr-90. I can tell you that the contamination
was not at all uniformly distributed. We checked the clothes of the person
and we used a large area probe, which is calibrated in Bq per cm2, which is
because of the large area very sensitive and gives an average. But we
thought that this was not enough and we made autoradiographies, which showed
that the contamination was actually concentrated within a few cm2. This
information was very valuable, because it helped us to find out about the
mechanism of contamination, which we will avoid in the future.

Franz
Schoenhofer
Habichergasse 31/7
A-1160 WIEN
AUSTRIA/EUROPE
Tel./Fax:	+43-1-4955308
Tel.:		+43-664-3380333
e-mail:		schoenho@via.at