1983-06-03_REVISION - M1977285 (2)

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43.90(1)(1)(i) • (i) be effective for 1,000 years to the extent reasonably • achievable and, in any case, for at least 200 years; and (ii) limit releases of radon-222 from uranium byproduct materials and radon-220 from thorium byproduct materials to the atmosphere so as not to exceed an average relea,~e rate of 20 picocuries per square meter per second (pCi/m s) to the extent practicable throughout the effective design life determined pursuant to (i) above. (2) In computing required tailings cover thicknesses, moisture in soils in excess of amounts found normally in similar soils in similar circumstances shall not be considered. Direct gamma exposure from the tailings or wastes should be reduced to back- ground levels. The effects of any thin synthetic layer shall not be taken into account in determining the calculated radon exhala- tion level. Cover shall not include materials which contain elevated levels of radium. Soils used for near-surface cover must be essentially the same, as far as radioactivity is concerned, as that of surrounding surface soils. If non-soil materials are proposed as cover materials, the licensee shall demonstrate that such materials will not crack or degrade by differential settlement, weathering, or other mechanisms over the long term. (3) The design requirements for longevity and control of radon • releases apply to any portion of a licensed and/or disposal site unless such portion contains a concentration of radium in land averaged over areas of 100 square meters, which as a result of byproduct material does not exceed the background level by more than: (i) S picocuries per gram (pCi/g) of radium-226, or in the case of thorium byproduct material, radium-228, averaged over the first 15 centimeters (cm) below the surface; and (ii) 15 pCi/g of radium-226, or in the case of thorium byproduct material, radium-228, averaged over 15-cm thick layers more than 15 cm below surface. (4) The licensee shall also address the nonradiological hazards associated with the waste in planning and implementing closure. The licensee shall ensure that disposal areas are closed in a manner that minimizes the need for further maintenance. To the extent necessary to prevent threats to human health and the envirornnent, the licensee shall control, minimize, or eliminate post-closure escape of nonradiological hazardous constituents, leachate, contaminated rainwater, or waste decomposition products to groundwater or surface waters or to the atmosphere. 43 - 23 (April 1990)