8 EXTENDED SUMMARY OF MANAGING ENVIRONMENTAL AND HEALTH IMPACTS OF URANIUM MINING, NEA No. 7063, © OECD 2014
PERCEPTIONS AND REALITIES IN MODERN URANIUM MINING
•
In modern, leading practice uranium mining, levels of occupational exposure today are far below
established regulatory limits. Dose limits have been adjusted accordingly and modern occupational
exposure is signicantly lower than historic levels of exposure. Corrective measures to successfully
reduce doses include using mining methods that limit the time that personnel work in high-grade
ore areas, providing cleaning areas to prevent the build-up of active material, monitoring to keep
personnel informed of higher dose areas and using shielding to reduce dose rates. Controlling worker
exposure to radon in uranium mines and mills also requires engineering designs and processes to
remove radon from the workplace. Radon gas produced during mining and milling is continuously
monitored, controlled and ventilated away from workers to avoid hazardous exposure. Presently,
worker exposure to radon and its decay products in the uranium mining and processing industry are
as low as, or only slightly higher than, public exposure to natural radon.
Public health and safety – members of the public have expressed concerns about the potential for
being exposed to higher than regulated limits of radon, uranium and other potential hazards, particularly
when residing in proximity to an active uranium mine. Radon releases into the atmosphere form a very
small portion of total human exposure (<1%), and releases beyond the licensed boundaries of the mine
and mill have been shown to be insignicant. Releases of uranium and other heavy metals into the
receiving environment can be effectively managed so as to limit them to acceptable levels.
Radon is a colourless, odourless gas and exposure in excess of regulated limits can increase the incidence of
cancer. However, off-site doses during operations, even historically, are generally relatively low (typically a small
fraction of the natural background dose). Studies show that within a very short distance from uranium mining and
milling facilities (usually around the site’s licensed boundaries), radon concentrations are close to background
levels measured at reference sites far from the facility.
•
Historically, the most signicant public radiation doses were associated with the post-closure phase
of the operation when restrictions on site access can be either lifted or ignored, allowing direct
exposure pathways to dominate in cases where sites have not been properly decommissioned and
remediated. During rehabilitation, radon emissions can be substantially reduced by installing a
soil or water cover on radon-emitting facilities. In cases where remediation has not been properly
completed, the continued exclusion of the public from higher risk areas through zoning and land use
controls or warning signs reduces the potential for increased public exposure.
•
With modern radiation protection and controls at the uranium mine facility, off-site members of
the public, even those living nearby the operations, are well-protected. Separation of the public from
the immediate direct sources of exposure is generally sufcient to ensure that doses remain low. In
addition, practices that reduce dust emissions, such as restricting emanating areas to a minimum
size and number and keeping tailings moist, reduce total emissions.
3. Ensuring that overall water quality is protected is of paramount importance to the success of the
facility. High performance standards implemented by the operator, effective regulatory oversight,
comprehensive monitoring programmes and public engagement are all key factors in dealing with
water quality issues. Water may be encountered in or near mine workings or used in extraction
processes. Mining activities can be undertaken in the proximity of water sources important to both
human and non-human biota. Uranium mining and milling can also be undertaken in dry regions,
where water is not readily available for make-up or process water and must be pumped into the site
from a considerable distance. Alternatively, mining can be undertaken in environments characterised
by large amounts of seasonal rainfall, where management of excess water may periodically require
signicant planning and effort.
•
Historically, early mine practices did not employ adequate control and treatment techniques, resulting
in the contamination of local watersheds, nearby low-lying areas and, in some cases, areas further
downstream. Drawdown of groundwater resources and groundwater quality impacts have also been
documented. Over time, however, and especially since the 1970s, standards for water releases have
been strengthened. Initially these improving standards were designed to protect subsequent human
use of water resources, but more recently they have been further developed to protect non-human