摘要(英) |
Due to high radioactivity of the spent nuclear fuel, to deposit it properly is an important issue. The almost recommended way is to store the radioactive waste in a specially designed copper canister and isolate it permanently in an underground deposition.
However, the complex thermal-hydro-mechanical coupling (THM) crucially affects the safety of the underground deposition. Conducting a rigorous numerical analysis is necessary to understand the effect of THM processes before construct the underground deposition. In this study, using the finite element software ABAQUS simulates how the decay heat generated by the nuclear fuel influences the temperature ,stress field and degree of saturation around the periphery of deposition.
Firstly ,in chapter 4, a parallel verification simulation about the evolution of temperature ,saturation ,pore pressure field and the change in min. principal stress field in a KBS-3H deposition drift will be conducted and compared to a report completed by SKB and Posiva to ensure the accuracy of the numerical model. The results of verification simulation show some similarity with the base case in the joint research report by SKB and Posiva.
In chapter 5, a sensitivity analysis about the effect of the horizontal fracture included a series cases of different thickness, position, heat conductivity and elastic modulus will be tested. Horizontal fracture in different condition will be added into the simulation and set around the KBS-3H deposition. The results indicate that the temperature in deposition rises if the thickness of fracture increases or the heat conductivity decreases when the value of heat conductivity of the fracture is lower than the intact rock ,this effect further causes the min. principal stress in the tunnel wall to increase. The min. principal stress in the tunnel wall also be influenced by the change in thickness, elastic modulus of the fracture. The min. principal stress increases if the thickness increases or the elastic modulus decreases, but if the fracture locates some distances away from the deposition, this effect is not significant. |
參考文獻 |
[1] SKB-Posiva, “TH and THM Modelling of a KBS-3H Deposition Drift”,Xavier Pintado,Ola Kristensson,Daniel Malmberg,Mattias Åkesson,Sebastiá Olivella,Ivan Puig,November 2017.
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