This deposit of brown coal is exposed in Jurassic
sediments along the southern shore of Issyk-Kul lake. The coal
is enriched in uranium (up to 0,3-0,4%) being in equilibrium
with radium.
The uranium minerals in the coal are distinguished as inclusions
of autunite and jarosite containing small points of uranyl phosphates.
The deposit was mined for uranium from 1948 to the early 90’s.
The ore was processed in a nearby plant located 3 km east of
the town of Kadji Sai. The coal was converted to ash pulp enriched
in uranium. The residuals of the pulp and the coal pulp with
radioactivity below 700 mR/h were rejected and stored in wastes
located in a tributary of the lake. The total volume of waste
reaches 400,000 m3 of radioactive and non-radioactive ashes,
covering a surface of 40,000 m2.
Although the coal mine has been closed, the radioactive
coal is still mined by the local population and used in the
town of Kadji Sai for domestic purposes. Only weathered (friable)
varieties of coal show high emanating capacity (up to 53% vs
25% for hard coal), but it is this coal that is mainly locally
used. Ashes from coal burning are dispersed in gardens in the
vicinity of the houses.
The former plant of uranic ore benefication
is situated in 3 km to East from the village.
Cropping of the coal-bed in the Kadji-Sai field
The use of this exceptionally
radioactive coal in Kadji Sai presents an excellent case study
for assessing the impact on the population of the domestic use
of radioactive coal: it allows to measure the effects of radiation
and radon emanation in houses, to control all pathways of radionuclides
from contamination of soils and groundwater by coal ashes to
the migration in agricultural and animal products.
