Experience with the tumulus technology for the disposal of solid low-level radioactive waste

As part of the development of a long-range plan for the disposal of solid low-level radioactive waste, Martin Marietta Energy Systems, Inc., has built a full-scale tumulus facility as a technology demonstration. This aboveground facility consists of a concrete pad on which the waste is placed, a synthetic underpad liner, concrete disposal vaults to contain the waste, a performance monitoring system, and a multilayered cap to be constructed after the pad is filled. Waste has already been placed on the pad, and the suitability of the design, the construction, and the operating procedures has been assessed. The facility appears to be acceptable with the exception of the underpad liner which will be eliminated in subsequent tumulus facilities. Radiation monitoring of the workers and environmental monitoring have shown essentially no impacts above background. Although a final assessment of the tumulus technology must await an evaluation after construction of the cap, plans are proceeding to construct additional tumulus facilities. 3 refs., 1 fig., 2 tabs.