Summary: Radioactive decay of radium, one of the principal contributors of radioactive emissions in uranium mill tailings, produces two distinct types of hazards. The first type is highly penetrating gamma radiation which, with sufficient exposure, can cause cancers such as leukemia. The second hazard, radon gas, produces other radioactive products which attach to particles in the air and are deposited in the lungs when inhaled. Exposure to large concentrations of radon products can increase the risk of lung cancer. Proper disposal of radioactive byproducts could prevent needless threats to public health.
The Nuclear Regulatory Commission is considering several tailings management approaches for one of the existing uranium mills. The possible approaches include covering the tailings with an earthen overburden, capping the tailings with clay and then covering with an overburden, removing the tailings to a prelined impoundment site, and removing the tailings to a mine pit. Covering the tailings with an earthen overburden would reduce the gamma radiation level to the estimated background radiation level, but would only reduce the radon gas emission level to about 50 times the natural background level. Capping the tailings with clay and then applying an overburden would further reduce the radon emission level, but the clay "cap" could slide off the tailings and take the overburden with it if sufficient amounts of water collect between the clay and the tailings. Removing the tailings to a prelined impoundment site would eliminate the possibility of the clay cap sliding off the tailings. If the tailings were to be removed to a mine pit and either fixed in concrete, asphalt, or clay, and the mine backfilled and replanted with vegetation, the chances of all future approaches by the public would be greatly diminished, radon emissions would be substantially reduced, and the tailings would be isolated from the environment.
