Progress in Waste Package and Engineered Barrier System Performance Assessment and Design

Abstract

As part of the U.S. Department of Energy's evaluation of site suitability for a potential high-level radioactive waste repository, long-term interactions between the engineered barrier system and the site must be determined. This requires a waste-package/engineered-system design, a description of the environment around the emplacement zone, and models that simulate operative processes describing these engineered/natural system interactions. Candidate designs are being evaluated, including a more robust, multi-barrier waste package, and a drift emplacement mode. Tools for evaluating designs and emplacement mode are the currently available waste-package/engineered-system performance assessment codes developed for the project. For assessments that support site suitability, environmental impact, or licensing decisions, more capable codes are needed. Code capability requirements are being written, and existing codes are to be evaluated against those requirements. Recommendations are being made to focus waste-package/engineered-system code-development.

Near-field/altered-zone models report

“…The most abundant corrosion products resulting from degradation of the waste container are expected to be iron oxides derived from a relatively thick overpack of low-carbon steel surrounding a corrosion-resistant inner barrier (Ahn and Soo, 1995;Van Luik et al, 1992). Based on proposed designs, approximately 1.6 to 2.0 × 10 4 kg of steel will surround each WP.…”

Materials to be used for radionuclide transport experiments (milestones SPL3A1M4)

“…The most abundant corrosion products resulting from degradation of the waste container are expected to be iron oxides derived from a relatively thick corrosion allowance overpack of low-carbon steel that is expected to surround a corrosion resistant inner barrier (Van Luik et al 1992;Ahn and Soo, 1995). This steel is expected to undergo generalized corrosion as a result of interaction with hot humid atmosphere and contact by liquid groundwater during the post dry-out period of the repository.…”

Software requirements specification document for the AREST code development

“…The U.S. Departmentof Energy (DOE) has assigned the task of managingand integratingthe performanceassessment studies at the proposed site for the undergroundnuclearwaste repository at Yucca Mountainto the Civilian RadioactiveWaste Management System (CRWMS) Management and OperatingContractor(M&O). The M&O has selected the AREST code as the waste package model for analyzing the engineeredbarriersystem (EBS) of the repository (Van Luik et al 1992). The AREST code was developed for the DOE at the Pacific Northwest Laboratory_l) (Liebetrauet al .…”