Implementation of Research and Development (R and D) Results in the Design of Liner System for the Near Surface Disposal Facility (NSDF) - 19089

Canadian Nuclear Laboratories (CNL) proposes to develop a Near Surface Disposal Facility (NSDF) at the Chalk River Laboratories (CRL) site in Ontario, Canada for disposal of CNL's Low Level Radioactive Waste (LLW) and other suitable wastes meeting the Waste Acceptance Criteria (WAC). The NSDF's Engineered Containment Mound (ECM) includes base liner and final cover systems. These liner systems are designed to perform effectively for a total of 550 years. The specified geomembrane in the NSDF detailed design is 2 mm thick High Density Polyethylene Geomembrane (HDPE GMB) double sided textured and white surface. CNL's approach to collaborate with Subject Matter Expert (SME) consultants and contractors, a Canadian university, and industry has enabled the NSDF to incorporate current best design practices, particularly for the design of the ECM's liner systems. This paper describes the HDPE GMB testing program and how the results of the state-of-the-art research have been utilized in the design of the NSDF's liner system and in selection of the best candidate materials to strengthen the confidence that the required service-life will be met. The testing program includes index properties and long-term performance evaluation tests of the five candidate HDPE GMBs using leachate simulant comparable to expected NSDF leachate and an index simulant used for testing many GMBs. The results of the tests are used as the basis to assess expected HDPE GMBs long-term performance. The expected long-term performance is applied as the key consideration for the final selection of the HDPE GMB in the NSDF project. Preliminary results of the testing program indicate that an expected service-life of 550 years will likely be met by the candidate HDPE GMB. (authors)