Coal ash

[don@radpro.uchicago.edu]

I just now happened to be reading UNSCEAR 1993.  Some numbers on coal ash 
from that report are given below.  

UNSCEAR-93 considered coal ash as an entrance path for radioactive
material into the biosphere ("Sources and Effects of Ionizing Radiation", 
United Nations Scientific Committee on the Effects of Atomic Radiation,
UNSCEAR 1993 Report to the General Assembly, United Nations, 1993, pp. 55- 
57).  Some numbers from that report:

Approx. 3 x 10 E9 kg of coal are required to produce 1 GW-year of electricity.
They estimate total global coal consumption for electricity production at  
3 X 10 E12 kg per annum.
 
An UNSCEAR 1982 report estimated average concentrations of K40, U238 and Th232
as 50, 20, and 20 Bq per kq of coal, respectively.  Coal from China, about 20%  
of the world total has 104, 36, & 30 Bq/kg of the three isotopes.
 
UNSCEAR 1993 reports average concentrations of nuclides in _fly ash_ as:


K40     265 (Bq/kg)
U238    200
Ra226   240 
Pb210   930
Po210  1700
Th232    70
Th228   110
Ra228   130 

UNSCEAR 1993 also estimates that smoke from coal burning annually ocontributes 
an additional 0.7 TBq of K40 and 0.3 TBq of each of the U238 & Th232 series
worldwide, assuming that smoke has the same composition as coal; the numbers 
are 20 times higher if smoke has the same content as fly ash.

Note that in many developed countries most of the fly ash is now removed from 
the smokestacks of coal fired plants.  One of the major uses of coal ash is 
the production of cinder blocks which UNSCEAR 1993 estimates contribute 
25,000 man Sv to the global collective dose.  


___________________________________________________________________

Don Jordan                          Tel. (312) 702-6299
Office of Radiation Safety          Fax        702-4008
The University of Chicago           email: don@radpro.uchicago.edu
1101 East 57th Street, Room 11
Chicago, Illinois  60637  
                -- Any opinions are the author's --