Radioactive Waste Management and Contaminated Site Clean-Up

Processes, Technologies and International Experience

William E Lee, Michael I. Ojovan, Carol M Jantzen

• Publisher: Woodhead Publishing
• Year: 2013
• ISBN:
  9780857097446
• Topic: Tecnología e ingeniería
• Subtopic: Gestión medioambiental

Radioactive waste management and contaminated site clean-up reviews radioactive waste management processes, technologies, and international experiences. Part one explores the fundamentals of radioactive waste including sources, characterisation, and processing strategies. International safety standards, risk assessment of radioactive wastes and remediation of contaminated sites and irradiated nuclear fuel management are also reviewed. Part two highlights the current international situation across Africa, Asia, Europe, and North America. The experience in Japan, with a specific chapter on Fukushima, is also covered. Finally, part three explores the clean-up of sites contaminated by weapons programmes including the USA and former USSR.Radioactive waste management and contaminated site clean-up is a comprehensive resource for professionals, researchers, scientists and academics in radioactive waste management, governmental and other regulatory bodies and the nuclear power industry.

• Explores the fundamentals of radioactive waste including sources, characterisation, and processing strategies
• Reviews international safety standards, risk assessment of radioactive wastes and remediation of contaminated sites and irradiated nuclear fuel management
• Highlights the current international situation across Africa, Asia, Europe, and North America specifically including a chapter on the experience in Fukushima, Japan

1

Fundamentals of radioactive waste (RAW): science, sources, classification and management strategies

W.E. Lee, Imperial College London, UK

M.I. Ojovan, University of Sheffield, UK

Abstract:

Classification systems for the types of radioactive waste (RAW) are described along with sources of controlled wastes (including from power production, military programmes, medical uses and research reactors) and uncontrolled or accidental releases. Options for managing controlled wastes from pretreatment, treatment, conditioning and storage stages through to transportation to final disposal are considered. Immobilisation (wasteform), temporary storage and permanent disposal options including near surface, deep and very deep geological disposal are covered as well as strategies for uncontrolled releases.

Key words

radioactive waste (RAW) classification

temporary storage

geological disposal

immobilisation

uncontrolled releases

1.1 Introduction

The big issue facing mankind at present is the need for population control. Our complete failure to address it, however, has meant that we are putting increasing pressure on our planet’s resources and negatively impacting on our environment. We are striving to fulfil our increasing need for power using a diverse portfolio of means including through nuclear fission. Nuclear fission has provided mankind with a significant proportion of our power for more than 50 years in a far more benign, low carbon and environmentally beneficial manner, and with a significantly lower loss of life in its generation than other sources such as coal, oil and gas. However, mankind has an innate fear of peaceful uses of nuclear energy because of the potential uses of nuclear weapons of devastating destructive ability such as those deployed at Hiroshima and Nagasaki, Japan in 1945. Moreover, mankind fears nuclear accidents, because if they occur, such as those at Chernobyl, Ukraine in 1986 and Fukushima, Japan in 2011, the time it takes to clean up is measured in decades if not centuries.

Sites of underground and above ground nuclear weapons testing and sites of accidental releases from research, manufacturing or storage facilities have left a complex legacy of contaminated land. Stockpiles of nuclear materials from weapons, submarine reactors and medical isotopes have all been allowed to gather without a definitive disposal disposition. Many of the first generations of nuclear power plant (NPP) have now reached the end of their lives and are in the process of being decommissioned (which again takes many decades). A lack of foresight by those building and designing these reactors, and a lack of political will (and finances) to address the issue of clean-up and waste disposal has meant that programmes to do so have become massive, complex, expensive and high profile. Large-scale decommissioning programmes require a national scale of activity, led by government and overseen by national and international regulators and oversight bodies. They require a coordinated approach and a need to be open with the public and stakeholders affected by the programmes.

Over the last 20 years or so action has begun to be taken. National bodies have been set up to oversee, coordinate and implement decommissioning of NPP and other contaminated sites, to treat, separate and immobilise waste in stable waste forms and to temporarily store in suitable packages and buildings prior to eventual permanent disposal in a geological disposal facility (GDF), also termed a repository. Nonetheless, progress varies from country to country and, from the public’s viewpoint, is slow and expensive. In this chapter we introduce the main types of nuclear waste and how they are classified and the major issues in decommissioning and clean-up, including strategies for the management of controlled wastes such as spent fuel (SF) from the open fuel cycle and high level wastes (HLW) from the partly closed fuel cycle as well as strategies for uncontrolled releases.

1.2 Controlled and uncontrolled wastes

Radioactive waste is material that contains, or is contaminated with radionuclides at concentrations or activities greater than the clearance levels set by the regulators, and for which no use is foreseen. The hazard associated with radioactive wastes depends on the concentration and nature of the radionuclides with those emitting higher energy radiation or being more toxic to life, being the most hazardous.

Radiotoxicity is the harmful effect of chemical substances as a result of their containing radioactive elements. The effect of ionising radiation emitted by the elements leads to changes in the metabolism and structure of living organisms. It is a measure of how harmful a radionuclide is to health. The type and energy of rays, absorption in the organism, residence time in the body, etc., all influence the degree of radiotoxicity of a radionuclide.

Alpha particles (He atoms) are very strongly ionising, so if they come into contact with atoms in a living tissue they can cause mutations, unusual chemical reactions in the cell and possibly cancer. Although the most ionising, it is the least dangerous form of radiation as long as it is not ingested or inhaled, because it is stopped by, for example, a sheet of paper or skin so that it cannot penetrate into your body. Alpha radiation is most commonly used in smoke detectors generated by americium.

Beta radiation is made up of an electron with high energy and speed. Beta radiation is more hazardous because it can also cause ionisation of living cells. Although it is less ionising than alpha radiation, it has the capability to pass through living cells and can be stopped by an aluminium sheet. If beta radiation hits a molecule of DNA it may cause spontaneous mutation and cancer. It is used industrially in thickness measurement such as in paper mills and aluminium foil production.

Gamma rays are high frequency, very short wavelength electromagnetic waves with no mass and no charge. They are emitted by a decaying nucleus so that it can release energy allowing it to become more stabilised as an atom. Gamma rays have the highest penetrating power, only being stopped by a few centimetres of lead or a few metres of concrete. They are the least ionising of the radiations but this does not mean that they are not dangerous. Gamma rays are likely to be emitted alongside alpha and beta radiation but some isotopes only emit gamma radiation. Gamma rays are useful because they can kill living cells and so be used to sterilise by, for example, destroying harmful bacteria. Gamma rays are also used in radiotherapy to kill off cancerous cells. They are also used to sterilise medical equipment, which is particularly useful in tools that would be melted by heat sterilisation or compromised by bleaches and other disinfectants.

Radioactive waste is accompanied by significant levels of radiation, hence it requires not only immobilisation to prevent radionuclides spreading around the biosphere, but also shielding and, in some cases, remote handling. A waste with activity concentrations equal to, or less than, clearance levels is considered non-radioactive. Radioactive wastes are either controlled or uncontrolled.

Controlled wastes are largely a product of the nuclear fuel cycle (NFC) used to generate electricity for civil use (Fig. 1.1). Wastes are generated during ore mining and processing to access the uranium metal or oxide, its enrichment and synthesis into fuel (the front end of the NFC), the operation and running of the reactor (operations wastes) and from fuel removal, treatment and disposal (the back end of the fuel cycle). Front end waste is contaminated basically with naturally occurring radionuclides, whereas operational waste also contains fission and activated products (typically low level waste (LLW) and to a lesser extent intermediate level waste (ILW); these are defined in Section 1.3). Front end wastes include contaminated mining wastes and uranium hexafluoride tails from enrichment. Operational wastes include spent filters and ion exchange resins, evaporator concentrates and absorber rods. Back end wastes include sludges from storage ponds, typically cemented ILW and vitrified HLW from reprocessing or spent fuel if direct disposal is planned.

1.1 Sources of radioactive waste (adapted from Ojovan and Lee, 2005). HLW = high level waste, ILW = intermediate level waste, LLW = low level waste, SRS = sealed radioactive sources.

During the early part of the nuclear era, consideration was not given to disposal of radioactive waste. As a result some NFC wastes (now termed legacy or historic wastes...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributor contact details
• Woodhead Publishing Series in Energy
• Foreword
• Preface
• Chapter 1: Fundamentals of radioactive waste (RAW): science, sources, classification and management strategies
• Chapter 2: Radioactive waste (RAW) categories, characterization and processing route selection
• Chapter 3: International safety standards for radioactive waste (RAW) management and remediation of contaminated sites
• Chapter 4: Technical solutions for the management of radioactive waste (RAW): overview and methods of selection
• Chapter 5: Irradiated nuclear fuel management: resource versus waste
• Chapter 6: Radioactive waste (RAW) conditioning, immobilization, and encapsulation processes and technologies: overview and advances
• Chapter 7: Assessing and modelling the performance of nuclear waste and associated packages for long-term management
• Chapter 8: Remediation of radioactively contaminated sites and management of the resulting waste
• Chapter 9: Safety and risk assessment of radioactive waste (RAW) and contaminated sites
• Chapter 10: Russia: experience of radioactive waste (RAW) management and contaminated site clean-up
• Chapter 11: Ukraine: experience of radioactive waste (RAW) management and contaminated site clean-up
• Chapter 12: Czech Republic, Slovak Republic and Poland: experience of radioactive waste (RAW) management and contaminated site clean-up
• Chapter 13: Nordic countries: experience of radioactive waste (RAW) management and contaminated site clean-up
• Chapter 14: Germany: experience of radioactive waste (RAW) management and contaminated site clean-up
• Chapter 15: France: experience of radioactive waste (RAW) management and contaminated site clean-up
• Chapter 16: England and Wales: experience of radioactive waste (RAW) management and contaminated site clean-up
• Chapter 17: Scotland: experience of radioactive waste (RAW) management and contaminated site clean-up
• Chapter 18: United States: experience of radioactive waste (RAW) management and contaminated site cleanup
• Chapter 19: Canada: experience of radioactive waste (RAW) management and contaminated site cleanup
• Chapter 20: South Africa: experience of radioactive waste (RAW) management and contaminated site clean-up
• Chapter 21: Republic of Korea: experience of radioactive waste (RAW) management and contaminated site clean-up
• Chapter 22: China: experience of radioactive waste (RAW) management
• Chapter 23: Japan: experience of radioactive waste (RAW) management and contaminated site clean-up
• Chapter 24: Fukushima: The current situation and future plans
• Chapter 25: Management of radioactive waste (RAW) from nuclear weapons programmes
• Chapter 26: Modeling and strategy approaches for assessing radionuclide contamination from underground testing of nuclear weapons in Nevada, USA
• Chapter 27: Remote monitoring of former underground nuclear explosion sites predominantly in the former USSR
• Index