Radioactive waste management in France: safety demonstration fundamentals

Abstract

The main challenge in development of the safety case for deep geological disposal is associated with the long periods of time over which high- and intermediate-level long-lived wastes remain hazardous. A wide range of events and processes may occur over hundreds of thousands of years. These events and processes are characterised by specific timescales. For example, the timescale for heat generation is much shorter than any geological timescale. Therefore, to reach a high level of reliability in the safety case, it is essential to have a thorough understanding of the sequence of events and processes likely to occur over the lifetime of the repository. It then becomes possible to assess the capability of the repository to fulfil its safety functions. However, due to the long periods of time and the complexity of the events and processes likely to occur, uncertainties related to all processes, data, and models need to be understood and addressed. Assessment is required over the lifetime of the radionuclides contained in the radioactive waste.

Implementation and verification of a user‐defined element (UEL) for coupled thermal‐hydraulic‐mechanical‐chemical (THMC) processes in saturated geological media

“…Figure 6 plots the UEL results together with the analytical solution by Cheng and Detournay 43 Here the same poromechanical parameters as the previous verification test are used. Pressure is normalized by its initial value and the dimensionless time is defined as t = 𝐶 𝑣 𝑡∕𝑎 2 where C v is defined in Equation (53). A satisfactory agreement is observed, confirming the HM capability of the UEL.…”

“…Safe and permanent storage of spent nuclear fuel and other high‐level radioactive wastes (HLWs) has been a pressing challenge given the ever‐increasing amount of HLWs and the shortage of long‐term storage facilities 1 . With multiple approaches being discussed, an international consensus is that deep geological disposal is the preferred solution to the final management of HLW 2 . This technology is based on a combined natural and engineered multi‐barrier system, where the host rock can efficiently retard the migration of hazardous radionuclides from the repository to the biosphere should a critical event happen.…”

“…approaches being discussed, an international consensus is that deep geological disposal is the preferred solution to the final management of HLW. 2 This technology is based on a combined natural and engineered multi-barrier system, where the host rock can efficiently retard the migration of hazardous radionuclides from the repository to the biosphere should a critical event happen. Because of the large time scale at concern, an important part of the design and performance assessment of underground HLW repositories is to predict the long-term evolution of the strongly coupled thermohydraulic-mechanical-chemical (THMC) processes in the clay buffers and the host rocks induced by material or energy release from the waste canisters.…”

Research Progress on the Corrosive Environment Large-Scale Evolution for Nuclear Waste Container

“…At present, it is based on numerical simulations to predict the corrosion of the nuclear waste container on a large time scale. According to the production of high-level nuclear waste, each country determined the three-dimensional structure of the nuclear waste container and analyzed the time evolution of the corrosion environment on the surface of the container (Ouzounian et al, 2012).…”