Proposed Actinide Source-Term Waste Test Program, Los Alamos National Laboratory, Los Alamos, New Mexico. Environmental assessment, Revision 7

摘要

The Waste Isolation Pilot Plant (WIPP) is a full-scale pilot plant designed to demonstrate the feasibility of long-term management, storage, and disposal of transuranic (TRU) waste from the environment. Environmental Protection Agency (EPA) regulations for disposal systems of transuranic wastes require development of performance assessments to provide a basis for a reasonable expectation that cumulative releases to the accessible environment will not exceed the quantities specified in 40 CFR 191 Subparts 6 and C (EPA 1993). One of the major criteria established by performance assessments is an analysis that estimates the cumulative releases of radionuclides (actinides), considering the associated uncertainties, caused by all significant processes and events. The most likely scenario to cause a release of radionuclides -- in this case, the actinide elements thorium through americium -- is the inadvertent intrusion of drilling into the waste storage areas. This activity could allow brine, which occurs naturally in pockets in the geological formations that make up the WIPP infrastructure, to enter and contact the salt-encrusted waste containers. Brine coming into contact with the waste containers could eventually cause a breach in the container walls, allowing their actinide content to become available for transport to the accessible environment. This Environmental Assessment (EA) analyzes the proposed action of the Actinide Source-Term Waste Test Program (STTP) as a means of providing data on the behavior of actinide elements in brine to help evaluate WIPP compliance with 40 CFR 191 Subparts B and C. The STTP is designed to measure the concentrations of actinides in actual TRU waste that has been immersed in brine. The proposed action would be a two- to five-year study to measure the concentration of actinides in brine and the composition of effluent gases in the test container as a measure of brine radiolysis and other processes.