Evaluation of Gas Migration and Rock Damage Characteristics for Underground Nuclear Waste Storage Based on a Coupled Model

Yi Xue,Zhengzheng Cao,Rongjian Li,Fang Shi,Faning Dang

doi:10.1155/2018/2973279

Abstract

In the deep geological repository of nuclear waste, the corrosion of waste generates gas, which increases the storage pressure, changes the properties of the rock strata, and affects the stability of nuclear waste repository. Therefore, it is of great importance to understand the gas migration in the engineering barrier and the potential impact on its integrity for the safety assessment of nuclear waste repository. A hydro-mechanical-damage model for analyzing gas migration in sedimentary rocks is established in this paper. On the basis of which, a set of coupled formulas for the coupling of gas migration in rock mass is established. The model considers the characteristics of gas migration in sedimentary rock, especially the microcracks caused by the degradation of elastic modulus and damage, and the coupling between the rock deformation and failure of fractures. The numerical simulation of gas injection test is beneficial to understand the mechanism of gas migration process in sedimentary rock.

Highlights

Nuclear waste contains strong radioactivity, large calorific value, high toxicity, and long half-life nuclides, which should be isolated from the environment for human residence in a reliable way
Because the excavation damage zone (EDZ) is mostly concentrated near the excavation wall, we mainly focus on the area of 0.5m×0.5m around the borehole
When the lateral pressure coefficient λσ = 3, the damage distribution and permeability distribution of surrounding rock appear in butterfly shape

Summary

Introduction

Nuclear waste contains strong radioactivity, large calorific value, high toxicity, and long half-life nuclides, which should be isolated from the environment for human residence in a reliable way. In a large number of disposal schemes, the deep geological disposal of nuclear waste is a widely accepted and feasible disposal scheme at present [1,2,3,4]. The geological disposal of nuclear waste is to lay waste in the geological body 500∼1000 m away from the surface, so that it can be isolated from the living environment of mankind permanently. The underground engineering of high level radioactive waste is called nuclear waste repository. Nuclear waste repository is a special deep underground engineering. The disposal of nuclear waste in deep sedimentary rocks has been studied by some countries. The gas will be generated in underground nuclear waste repository due to the metal corrosion

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Conclusion