8

Waste sources and classification

D.F. McGinnes

NOK (Northeast Switzerland Power Company), Baden, Switzerland

2.1. Introduction

The objective of this chapter is not only to describe the various sources of radioactive wastes, their classification and how they are conditioned for disposal, but also to examine issues that are of interest in a broader environmental context.

It should be recognised by the fact that the topic ‘‘waste sources and classification’’ is addressed at the beginning of this book that it is one of the key elements in any disposal programme. Without a proper understanding of radioactive wastes, namely their chemical, physical and radiological properties, it is not possible to correctly design a repository, or to assess the safety of any proposed facility for the handling, storage or disposal of these materials. The direct implication of this statement is that, without a reasonable inventory that bounds the waste types that are expected to be disposed of in a planned repository, the situation could arise that some of the waste may not, at the time of disposal, meet the repository acceptance criteria and hence not be placed in a given repository.

To this end, one of the basic requirements for a disposal programme is the creation of an inventory that documents all radioactive wastes that are expected to arise for disposal. The requirements for such an inventory will form a key part of this chapter.

2.2. Radioactive waste

Radioactive waste is defined by the International Atomic Energy Agency (IAEA, 1994) as ‘‘Any material that contains or is contaminated by radionuclides at concentrations or radioactivity levels greater than the exempted quantities established by the competent authorities, and for which no use is foreseen.’’

However, it should be recognised that one person’s waste may be another person’s resource and this holds true, to a certain extent, for radioactive waste, although it is normally national policy that determines this point.

For spent fuel (SF), some countries define this material as a resource for recycling, and not as a waste, with the intention of separating the uranium and plutonium for re-use as

fuel in reactors (see section 2.4.1.4). In other countries, the opposite is true and SF is considered as a waste. However, it should be pointed out that this is generally not a simple decision based on economic assessments and left to the owners of the SF (as would be the case in nearly any other business), but is often based on political considerations. For example, the original governmental policy in Germany in the 1970s and 1980s was that SF could only be produced if contracts existed for its reprocessing. Around 15 years later, this was followed by an unsuccessful governmental attempt to force the cancellation of some of these contracts and a complete ban on reprocessing came into force in 2005. However, a more understandable rationale is that based on security of energy supply. This has recently led to the recommendation in Japan for active commissioning of a domestic reprocessing plant. If this had been left to pure economic forces, the decision would probably have been otherwise. Therefore, whether SF is treated as a waste or not is often a matter of national policy.

2.3. Waste classification

Radioactive waste requires appropriate handling and management to ensure the safety of workers, the general public and the surrounding environment due to the radiation emitted. However, not all radioactive waste produced has the same level of potential hazard.

Classification (or grouping) of radioactive wastes makes it easier to determine how to handle the wastes generated and also helps to identify suitable disposal options. Definitions for the classification of waste vary from country to country and, as such, make comparison difficult (see comments in IAEA (1994) and Vankerckhoven and Mitchel (1998)). To circumvent this, the IAEA has recently implemented a waste management database (NEWMDB, see Csullog et al., 2001), which attempts to harmonise waste declarations (Table 2.1).

However, it should be emphasised that these are general criteria and it is recommended that the pertinent national regulations are examined to determine what applies in any particular country For example, in the UK, which has an operating LLW repository (the Drigg site in Cumbria), the following classifications apply (RWMAC, 1997):

Table 2.1

Details of the waste classes defined by the IAEA (from Csullog et al., 2001)