Quality assurance plan for placement of cold-cap grout, demonstration vaule, Hanford Grout Vault Program. Final report

摘要

During FY 91, the U.S. Army Engineer Waterways Experiment Station (WES) developed a grout to be used as a cold cap, a nonradioactive layer, between the solidified waste and the cover blocks of a demonstration waste disposal vault at the U.S. Department of Energy Hanford Facility. This document recommends requirements for a quality assurance (QA) plan for field mixing and placing of the cold-cap grout during final closure of the demonstration vault. Preplacement activities emphasize selection and testing of materials that will match the performance of materials used in the WES grout. Materials sources and applicable American Society of Testing and Materials, American Concrete Institute, and American Petroleum Institute specifications and requirements are provided. Archiving of physical samples of materials is essential, in addition to careful maintenance of test reports and laboratory data. Full-scale field trial mixing and a detailed preconstruction conference are recommended. Placement activities focus on production and placement of a grout that remains sufficiently constant throughout all batches and meets performance requirements. QA activities must be coordinated between the batch plant and delivery site. Recommended sampling during placement includes cylinders cast for subsequent tests of compressive strength and for nondestructive evaluation and prisms cast for monitoring volume stability. A minimum of two lifts is recommended. Postplacement activities include long-term monitoring of the properties of grout specimens cast during placement. Minimum testing of cylinders includes pulse velocity, fundamental frequency, and unconfined compressive strength. Monitoring characteristics of the microstructure also are recommended. The QA plan should designate an organization to have responsibility for maintaining complete records, reports, and archived samples, including details of deviations from plans written before field placement.