Design Principles and Approaches for Radioactive Waste Repositories

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• Publisher: International Atomic Energy Agency
• Year: 2020
• eBook ISBN: 9789201131201
• Topic: Technology & Engineering
• Subtopic: Mechanical Engineering
• Index: Technology & Engineering

A considerable level of international experience has been gained over the last decades in designing radioactive waste disposal facilities. This publication is intended to assist Member States in planning for the disposal of radioactive waste. Specifically, this publication describes the approaches and principles to be considered by the responsible organizations within a Member State involved in the planning and design of radioactive waste disposal facilities. Examples are provided for all waste classes requiring disposal. The examples are based on successfully implemented designs or on design concepts that are sufficiently advanced to demonstrate their overall feasibility for the safe disposal of radioactive waste. Alternate disposal options are also discussed, describing solutions that rely on the conversion of existing facilities, such as mines or other underground openings as well as the potential for disposal in boreholes.

1. Introduction

1.1. Background

Radioactive waste in various forms is generated in industrial, research and medical facilities worldwide. For those countries with nuclear power programmes, these wastes are predominantly derived from energy production in nuclear power plants. Almost all countries produce smaller quantities of radioactive waste from research activities and medical and industrial applications. Each IAEA Member State thus possesses different types of radioactive waste in varying quantities that will eventually require disposal, in conditioned, solid form, in one or more purpose designed disposal facilities.

The path to disposal for each type of waste will depend upon its inventory of radionuclides, its physical and chemical form, its quantity, and other waste specific characteristics. Depending on the category of waste, quantities within a national inventory can range from a few cubic metres to hundreds of thousands. The radiological hazard will also vary, depending on the nature and amounts of radionuclides associated with each type of waste. Radioactive waste can remain hazardous to human health and the environment for a period lasting from a few decades to many thousands of years, depending on the radionuclides of concern and their concentrations. Unless the quantity is considered below defined clearance levels or exempted by national law based on very low radiation levels, all radioactive waste is considered hazardous, no matter the actual quantity, and is therefore subject to controlled and regulated disposal. The Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management [1] requires that each Contracting Party to the Convention provide assurance that “society and the environment are protected from harmful effects of ionizing radiation, now and in the future…” The recognized means by which assurance is provided is the safe management of radioactive waste through disposal in a purpose built repository. Member States are ultimately responsible for providing adequate resources and ensuring their efficient use to manage radioactive waste from initial generation to eventual disposal.

Significant experience in the disposal of radioactive waste has been gained over the last several decades. Numerous facilities have been constructed and operated in many Member States and disposal solutions for many waste forms and classes are available. Based on this and other experience, a Member State beginning the development of a new disposal facility will need to go through a design process that produces an optimized solution for the inventory under consideration. This publication is intended to provide such Member States with an overview of possible repository design principles and approaches that can be implemented. In addition, this publication describes concepts and existing facilities to provide illustrations of possible disposal solutions for consideration.

The number of Member States with plans to construct a radioactive waste repository is increasing. Decisions regarding the selection of an appropriate repository for design and implementation are important for the entire national radioactive waste management system. In particular, these can affect upstream consideration of how the waste will be managed from the point of its generation. Although each national repository project has unique features, it is possible to identify a range of basic design solutions suitable for disposal of all classes of radioactive waste.

This publication describes the range of waste types that can be disposed of in a variety of facilities, based on the intrinsic characteristics of the wastes. For example, near surface disposal of low level waste has progressed in several countries for over 50 years [2]. Several such facilities that exist worldwide have already applied experiences and lessons learned from antecedent facilities. Waste with higher levels of radioactivity has been routed for geological disposal in a number of different geological settings. Member States are encouraged to continue to take advantage of previous international work and build upon designs that have been demonstrated to function, within the constraints of their national policies. Examples of more recently established disposal facilities illustrate the application of previous experience and lessons learned from older facilities. These practices enrich the knowledge base for the disposal of nuclear waste and will serve as examples in this publication.

1.2. Scope

This publication provides an overview of design principles and approaches that have either already been fully implemented, or are in the implementation phase, in several Member States. Examples of mature designs are provided for a wide range of radioactive waste types and geological settings. Potential repository solutions are based on the characteristics of the waste, such as volume and radiotoxicity, and available conceptual disposal options. The approach presented is based on fundamental safety principles [3, 4] and uses a systems engineering, requirements driven design approach that can be considered a primer for the design of radioactive waste disposal facilities.

The design approach is staged. From the earliest conceptual designs to the final as-built state, each design stage increases the technical basis and refines the repository configuration and disposal concept. Each stage can be iterative, and the output from each stage provides input for the next. The stages of design comprise an evolving programme. If guiding design principles are applied along the way, the implementer will increase the likelihood of accomplishing a successful repository project.

As well as the guidance on good practices relevant to radioactive waste disposal presented in this publication, the IAEA is considering providing further guidance with a focus on the technical, scientific and programmatic aspects of implementing a disposal solution. Future publications with a technical and scientific focus could reflect international experience with the management of site investigations for a disposal facility; provide an overview of past experiments conducted in underground research facilities around the world, as a scientific and technical basis to developing a geological disposal system; discuss the engineering and technical specifications of a borehole disposal concept for disused sealed radioactive sources; and explore disposal concepts showing a potential for the safe and effective disposal of small waste inventories. Other future publications could discuss some of the wider programmatic considerations needed for successful disposal implementation, reflecting international experience with cost estimation methods and funding sche...

Table of contents

• 1. Introduction
• ABREVIATIONS
• CONTRIBUTORS TO DRAFTING AND REVIEW