Geologic Disposal of Low- and Intermediate-Level Radioactive Waste

Roland Pusch, Raymond N. Yong, Masashi Nakano

• Publisher: CRC Press
• Year: 2017
• Print ISBN: 9781498767965
• eBook ISBN: 9781351795081
• Topic: Law
• Subtopic: Environmental Law
• Index: Law

This book will address concepts and techniques for preparation and disposal of low- (LLW) and intermediate-level (ILW) radioactive waste from the nuclear industry, the weapons industry, university labs, research institutes, and from the commercial industry. It will aid decision-makers in finding optimal technical/economical solutions, including how site investigations, design, construction, identification and selection of construction materials (clay and concrete), and monitoring can be made. It will also examine techniques for isolating soil and rock contaminated by leaking nuclear plants and from damaged nuclear reactors such as those at the Fukushima and Chernobyl nuclear plants.

1 Radiation and Radioactive Wastes

1.1 INTRODUCTION

This chapter is an introduction to the book and is intended to indicate what the authors think is absolutely essential in planning and designing repositories for low- and intermediate-level radioactive waste. Their first and firm statement is that the most demanding problem with nuclear power is to find space for disposing the very large and quickly growing amount of such worthless and hazardous waste. Technical solutions to this problem are at hand, as the book shows, while public acceptance of proposed sites for disposal and the risk for disseminating radioactivity by terrorist actions remain to be handled. The first item—the technical solutions—is what this book is about. The other has to be solved by society and its political representatives.

1.2 IS THERE A PROBLEM?

The man in the street has heard about the problems with nuclear power: questionable reactor safety, too high costs per produced kilowatt-hour, and lack of agreement of how radioactive waste can be safely disposed of. We will confine ourselves here to deal with the latter issue and focus on disposal of slightly and moderately dangerous waste that we will define as low-level radioactive wastes (LLWs) and intermediate-level radioactive wastes (ILWs) in the following chapters. National environmental protection authorities and mass media have not paid much attention to such wastes but have concentrated on discussing safe storage of high-level radioactive wastes (HLWs), like spent reactor fuel. The reason is of course the much higher radioactivity of such waste and the very long time that has to pass before it is no longer threatening to living species. Spent reactor fuel can be reprocessed for preparing new reactor fuel, but the procedure is complicated, costly, and risky, but still considered feasible: it remains to be a future solution of the problem in utilizing nuclear power.

It should be added here that LLW and ILW are generated from various other useful activities, such as mining operations, industries, and medical treatment, as well as from laboratory and field tests in a number of scientific research branches other than that of nuclear technology for energy production.

While LLW contains only about 1% of the total radioactivity generated over the lifetime of a nuclear power plant, it can make up 90% of the total volume of radioactive waste. As LLW cannot be disposed of conventionally as normal rubbish, it is segregated, measured for radioactivity, processed, and placed into strictly engineered and monitored waste disposal facilities, as with ILW.

The present interest is for LLW and ILW containing long-lived radionuclides since they have to be stored for tens to hundreds up to thousands of years. There are several options for disposal: landfill on-ground and underground containment in newly constructed repositories or certain types of abandoned mines, or placement in deep shafts. For LLW and most ILW that this book deals with, isolation from groundwater and the biosphere is required for a much shorter period—a few hundred years. The major goal is to provide effective isolation, but also to find the required space for storage. The need for such space is continuously growing, and in countries with limited available ground surface for disposal, like Japan, Switzerland, and the United Kingdom, one may have to use underground disposal. This raises the problem of finding suitable rock with a low groundwater percolation rate and sufficient mechanical stability. These properties are in fact also important for on-ground disposal since rainwater and meltwater percolating a site where LLW and ILW are stored will migrate into the underground and reach the bedrock directly or via soil layers. Radioactive contamination of the groundwater may take place in either case.

1.3 WHAT GEOLOGICAL MEDIA AND MATERIAL CAN BE USED FOR ISOLATING WASTE?

The basis of the whole matter is geology, and we will give a brief summary of the major types of rock and soil that we are concerned with. Later in this book, we will discuss how engineering aspects determine the possibilities and limitations of using geological media for the disposal of radioactive waste of different kinds. This will make it obvious that it is often not the mineral composition that is decisive in this respect, but that the role of buildup and coordination of strong and weak elements—what we call soil and rock structure—are of primary importance. They determine not only the mechanical stability of these media but also how ground- and surface water, which can be carriers of radionuclides emanating from stored waste, are distributed and perform on small and large scales.

As is commonly done when dealing with the disposal of highly radioactive waste, one distinguishes primarily between crystalline rock, salt rock, argillaceous rock, and clastic clay (Svemar 2005). This simplification is because most rocks have properties that are either strong or brittle (igneous, magmatic rock), creeping (salt), brittle but somewhat ductile (metamorphic, argillaceous rock), and ductile (clastic clay). We will not deal here with the origin or genesis of different types of soil and rock but merely show typical mineral constellations that give them practically important properties. Salt consisting of halite (NaCl) or sylvite (KCl) is well defined and known for its creep behavior.

Since soil is commonly the ultimate degradation product of rock, we will begin with rock, for which we have to use common petrological terms (Tables 1.1 through 1.3). Major soil types of importance in the present context are listed in Table 1.4. We will exa...

Table of contents

• Cover
• Halftitle Page
• Title Page
• Copyright Page
• Dedication Page
• Table of Contents
• Preface
• Authors
• Chapter 1 Radiation and Radioactive Wastes
• Chapter 2 Radioactivity and Radiation Hazards
• Chapter 3 Low- and Intermediate-Level Radioactive Wastes
• Chapter 4 Function of LLW and ILW Isolation
• Chapter 5 Management Disposal Schemes
• Chapter 6 Design and Function of Repositories
• Chapter 7 Construction of LLW and ILW Repositories
• Chapter 8 Long-Term Function of LLW and ILW Repositories
• Chapter 9 Quality Assurance and Safety Assessment
• Index