Abstract: In order to study the interaction mechanism between fracture water flow, heat transfer and distance between disposal pits in the near field of high-level radioactive waste repository, 3DEC software is used to calculate the influence of the interaction of fracture water flow, heat transfer and distance between disposal pits on the near-field temperature distribution of the disposal repository. Results show that: (1) Under the same disposal pit spacing, the flowing fracture water changes the temperature field near the disposal pit, decreases the rock mass temperature, and obviously shortens the time required for the model to reach steady state; (2) The larger the distance between the disposal pits, the weaker the temperature superposition effect. The lower the near-field temperature of the disposal repository, the lower the temperature of bentonite of waste tank surface. The lower the water temperature at the outlet of the fracture, the shorter the time required for the model to reach a steady state; (3) The temperature in downstream area of near-field fracture water flow is significantly higher than that in upstream area of fracture water flow in the disposal reservoir due to joint heat transfer between horizontal and vertical fracture water flows; (4) The water temperature of horizontal fracture water outlet is higher than that of the vertical fracture water outlet when the spacing of the disposal pit is 6 m and 8 m, but the water temperature of the horizontal fracture water outlet is lower than that of the vertical fracture water outlet when the spacing of the disposal pit is 10 m.

Key words: high-level radioactive waste, fracture water flow, heat transfer, disposal pits distance, numerical analysis