Technical Meeting on Achievements in Radioactive Waste Characterization

Introduction

Radioactive waste is generated from the operation of nuclear power plants, nuclear fuel cycle facilities, and from the use of radionuclides in research, healthcare, accelerators, and industrial applications. Depending on its origin, radioactive waste can vary in type, covering a wide range of radiological, physical, and chemical properties. Characterizing radioactive waste involves determining these properties, playing important roles at various stages of safe management, from generation to disposal. Another important aspect is the interpretation of the properties into measures taking care that wastes are treated safely for mankind and environment during their life cycle. For example, it can help establish the appropriate treatment and/or conditioning needed, provide information necessary for process control, and ensure that the waste form or waste package meets the waste acceptance criteria for processing, storage, transport, and disposal.

The safe management and disposal of radioactive waste partly rely on accurate and quality-assured characterization through both non-destructive and destructive methods, as well as on determining the radionuclide inventory. Relevant procedures, standards, and laboratory practices have been developed and refined over the years in expert laboratories within Member States of the International Atomic Energy Agency (IAEA) that possess mature operating nuclear facilities and laboratories. However, several Member States with less developed programs lack such facilities and laboratories. For these countries, achieving satisfactory characterization programs and interpretation of results poses a complex technical challenge requiring both intellectual and financial resources.

The purpose of characterization including interpretation is to provide verified and documented properties for radioactive waste. This typically involves determining not only its radioactive properties but also its physical and chemical characteristics. This information serves as the basis for assessing the necessary actions to manage the waste and determine the appropriate disposal route. Ultimately, characterization ensures that the waste, its form, and its packaging comply with acceptance criteria for any subsequent processes, based on quality-assured information about its properties.

The activities conducted at various stages of the life cycle can significantly mitigate program risks and influence both local and strategic decisions. Moreover, they can impact the cost and efficiency of the overall waste characterization program. Characterization is typically easier and more cost-effective in the earlier stages of the life cycle. For instance, waste properties that are easily measured in the raw waste state may become difficult or impossible to measure after certain treatment or conditioning stages.

Efficient segregation and control of waste streams early in the life cycle can result in a greater proportion of waste falling into simpler and more stable categories. Conversely, mixing raw waste streams and losing valuable historical information can lead to more waste falling into complex and variable categories, necessitating a more intensive and costly characterization program.

The planning stage plays a crucial role in identifying characterization requirements for subsequent life cycle phases. Planning for waste characterization should occur prior to waste generation to ensure that waste collection, segregation, containerization, and temporary storage are all carried out in a controlled manner that best supports the waste characterization plan. Generally, the better the planning, the more cost-effective and successful the characterization program will be. It is understood that the planning should be developed systematically an