关键词: 高放废物处置库, 传热模型, 温度场, 解析解 

Abstract: The temperature distribution characteristic of a high-level radioactive waste disposal repository is important for evaluating its safety performance and designing appropriate thermal dimensions. Based on the conceptual design of the KBS-3V disposal repository, a two-dimensional axisymmetric heat transfer model for a single nuclear waste canister is established. By means of the finite Fourier sine transform, the separation of variables and the impulse theorem, an analytical expression is obtained from which the surrounding rock temperature at any point, under a single-waste-canister heat release condition, can be determined. The validity of the proposed model is verified by comparing the results of existing semi-analytical solutions with linear heat source solutions. The surface temperature of the waste canister is obtained by superposing the temperature difference of the buffer layer on the rock wall temperature, before analyzing the near-field temperature evolution of the waste canister. Finally, the effect of material thermal parameters, nuclear waste decay parameters, and geometric parameters on the waste canister surface temperature are analyzed. The results show that the near-field temperature of the waste canister increased rapidly, reaching a peak within the first two years of the canister being disposed of, after which the temperature decreases slowly with the disposal time. The buffer temperature gradient is large while the rock temperature gradient is small. The larger the thermal conductivity of the buffer material and surrounding rock, the thinner the buffer layer, the smaller the combustion value of nuclear waste, and the longer the cooling time, the lower the surface temperature of the waste canister. The thickness of the bentonite pellet layer has a greater effect on the surface temperature of the waste canister than that of the bentonite block layer, mainly because of the lower thermal conductivity of granular layer material.

Key words: high-level radioactive waste disposal repository, heat transfer model, temperature ?eld, analytical solution