Kullanılmış Nükleer Yakıtın Yatay Jeolojik Bertarafının Isıl Analizleri

Abstract

Geological disposal is the most accepted method for permanent disposal of spent nuclear fuel and high-level waste. There are various geological disposal concepts under development in many countries and these concepts have differences mainly in the geometry and material of disposal canisters, geological formations of host rock and orientation (vertical and horizontal) of disposal canisters. Thermal behavior of disposal facility components is an important determinant of repository design and waste disposal density (the amount of radioactive waste that can be safely emplaced per unit area of the geological repository). Thermal load of the geological repository strictly depends spent fuel characteristics (amount, isotopic composition, heat generation), disposal canister model and the thermal features of the host rock. In this study, canisters loaded with spent fuel assemblies discharged from VVER – 1200 and ATMEA1 reactors and disposed horizontally in the granitic rock are modeled. Spent fuel characteristics are evaluated by using the MONTEBURNS 2.0 code. The ANSYS finite element code is utilized to generate a thermal model of horizontal repository and determine waste disposal densities through thermal analysis by taking into account the thermal constraints. Thermal analysis is repeated for disposal canisters loaded with a various number of spent fuel assemblies (4, 5, 6 assemblies) and with assemblies precooled for various periods (40, 50, 60 and 70 years) in order to assess the impact to waste disposal densities. Most favorable canister model with regard to disposal density is determined.