Modelling and Numerical Simulation of Gas Migration in a Nuclear Waste Repository

TL;DR

This paper develops a detailed numerical model for simulating hydrogen gas migration in deep geological radioactive waste repositories, incorporating capillary effects and gas diffusivity to accurately capture gas phase changes.

Contribution

It introduces a novel compositional two-phase flow model with a unique variable choice that ensures consistent simulation of gas phase appearance and disappearance.

Findings

Model effectively simulates gas phase dynamics in repository conditions

Inclusion of capillary effects improves simulation accuracy

Demonstrates model's adequacy through computational examples

Abstract

We present a compositional compressible two-phase, liquid and gas, flow model for numerical simulations of hydrogen migration in deep geological radioactive waste repository. This model includes capillary effects and the gas diffusivity. The choice of the main variables in this model, Total or Dissolved Hydrogen Mass Concentration and Liquid Pressure, leads to a unique and consistent formulation of the gas phase appearance and disappearance. After introducing this model, we show computational evidences of its adequacy to simulate gas phase appearance and disappearance in different situations typical of underground radioactive waste repository.