The uncertainty was introduced by using a pdf for each param-eter that was accepted and compiled in the bibliography [22].
Characteristic values and limits for each distribution were chosen
from local information where available or values from bibliogra-phy on the contrary. Main parameters and associated distribution,
when used, are shown in Table 3.
Other parameters were fixed.
The exposure time considered for workers was 50 years, the
maximum time that a worker would be exposed to the radioactive
content in NORM wastes.
On the other side it was considered around a thousand years
for the assessment to the public, as some processes as erosion of
the cover or leaching to the ground water, will become important
after some hundreds of years. After that period it is considered that
control would disappear and any prediction would become use-less. The only protection which can be considered plausible after
that loss of control is that any human intrusion would detect the
existence of wastes, which will be analyzed in order to detect any
chemical or radioactive toxicity