RE: Re[2]: Side of a volcano

[Simon "M." Jerome <smj1@npl.co.uk>]

Good morning.

Surely the point is that the emission of material from Mount St Helens 
was distributed throughout the 4 km³ of ash and as such, the 
radioactivity was not concentrated at any one point. Given that, the 
figures could be read as;

K-40	555 kBq/m³
Ra-226	27.8 kBq/m³

This compares with the crustal average (data from the CRC Handbook of 
Chemistry & Physics, 75th edition) of;

K-40	~600 kBq/m³
Ra-226	~30 kBq/m³

Not a great difference.

At a Nuclear site is that although the discharge levels may well be 
lower, but the local concentration is somewhat higher.

It would, of course, be interesting to know if the Radon-222 and it's 
daughters rained out with the ash or escaped to the atmosphere. Either 
way, there is an additional 52 TBq (oh, alright...1400 Curies) each of 
Pb-210, Bi-210 and Po-210 around somewhere. 


Simon Jerome
National Physical Laboratory
UK

Email	simon.jerome@npl.co.uk
Internet	http://www.npl.co.uk/

************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html