Prospective testing program to evaluate EBS and closing technologies performances at the Radioactive Waste National Repository Băiţa-Bihor

摘要

Radioactive Waste National Repository (DNDR) Băiţa-Bihor, located in two disusedexploration galleries from Băiţa uranium mine, is designated since 1985 to accommodatearound 5000 m3 of in-drum conditioned short-lived radioactive wastes.At DNDR Băiţa-Bihor all the water that enters the system, responsible for the initiationof corrosion damage of the metallic drums, occurs through infiltration.Considering the importance of this facility for the Romanian nuclear program, in 2012was started a Joint Applied Research project for the development of the closurestrategy of National Repository of Radioactive Waste Băiţa Bihor (SARAWAD-BB)based on the evolution and optimization of the engineered barrier system (EBS) inorder to improve the radiological safety.The project is aiming to improve the disposal system by selection of a suitable technologyfor closure. For this reason, it is mandatory to develop a testing program, includingin-situ and laboratory corrosion testing program to asses EBS performances.The development of the preliminary testing program will be based on the repositoryhistory and, also, on other potential failure mechanisms that could generate prematuremetallic drum failure. There were anticipated several causes that can lead to thecorrosion damage of the metallic drums:- a potential manufacturing defect of the steel drum or of the protective coating systemthat could impair the serviceability of the metallic drum;- alterations of the disposal spaces due to potential high stresses applied to on themetallic walls of the drums;- localized corrosion phenomena as a result of microbial activity or of different aerationcells development etc;Considering the specific conditions inside the repository (old closed disposal galleryversus new active disposal gallery) with limited access to the metallic surfaces to bemonitored, authors are trying to propose an in-situ corrosion monitoring program, aspart of the whole testing program designated to evaluate EBS and closure technologiesperformances at DNDR Băiţa Bihor.Due to the complexity of the materials used as backfill, the assessment of redox conditionsimplies the development of an extended set of experimental data.Furthermore, this testing program will permit decision making on closure strategy,including sealing and backfilling materials, considering the forecasted interactionsbetween metallic surfaces and sealing/backfilling materials.