18.1.3 Radioactive waste management infrastructure

For countries that use nuclear power to generate electricity, waste storage may prove adequate for a time but what is actually needed is a permanent solution, namely a disposal facility. For LLW and LILW, a number of countries own and operate near-surface or intermediate-depth repositories, a few of which have been accepting waste since the 1950s. Over the years, public opinion has hardened against the opening of new facilities so that those that are in operation have come to be seen as valuable national assets and a crucial part of the nuclear infrastructure. It is common for governments to enshrine geological disposal of radioactive waste in national policy and to entrust a waste management organisation (WMO) to implement it. The WMO assumes the role of repository operator and is a key component of the waste management infrastructure.

Radioactive waste disposal is expensive. As yet, no facilities exist for deep disposal of SNF but for a medium-sized programme (5000 tHM) the cost of a deep repository is expected to be of the order of €5 Bn13 (2006 prices). This must ultimately be met from sales of electricity and, therefore, in advance of waste production. Normal procedure is to establish an oversight body with the power to create an accumulating fund that is dedicated to decommissioning and waste management. The fund is raised by some form of tax or surcharge on the price of electricity and the WMO may draw from it to pay for repository development.

A second important part of the infrastructure is the regulatory body, which should be independent of the repository operator. Regulations will be established to limit the hazards to both staff and public during the operational phase of a repository and after it has been closed. Often, the regulations governing repository operation will be established by the nuclear regulator while those applicable to the post-closure phase are set by the environmental regulator. Some jurisdictions place a limit on the time period over which post-closure safety must be demonstrated, others do not. Typically, peak doses tend to occur thousands, or even hundreds of thousands, of years after closure as a result of the migration of long-lived, mobile radionuclides such as technetium-99 and iodine-129 in groundwater. It follows that any ‘demonstration’ of post-closure safety will entail mathematical modelling based upon extrapolations of the past and present hydrogeology of the site.

For both operational and post-closure safety, an important consideration is that of optimisation of radiological protection and safety:

the magnitude of the individual doses, the number of people exposed and the

likelihood of incurring exposures [shall] all be kept as low as reasonably

achievable, economic and social factors being taken into account, within the

restriction that the doses to individuals delivered by the source be subject to dose

constraints14

Dose constraints for humans are usually set at 300 pSv per annum or less. This represents about one tenth of the average annual dose from natural background radiation. Because of the impossibility of knowing the habits (e. g. diet) of individuals living far into the future, dose calculations are usually performed for small groups of people who might be reasonably expected to be maximally exposed. A typical example is a group of people living in the repository discharge area and consuming produce raised on contaminated water.

The third component of the infrastructure is the waste producer — in most cases this is the NPP operator. These three bodies — WMO, regulator and waste producer — form the most important components of the waste management infrastructure as depicted in the so-called ‘classical triangle’15 shown in Fig. 18.2.