The condition of inventory will need to be managed to meet radiological, environmental and possibly other safety concerns.

For example, there may be chemical corrosion processes that affect the handling of fuel downstream in the disposal route. The timescale of these processes could impact the timing of certain operations depending on whether a corroded or an uncorroded state of the inventory is easier to manage. The gaseous chemical products of reaction may also be a concern, e. g. in Magnox plants, the Magnox/water reaction produces hydrogen (Twidale, 1999).

It may be possible to dilute liquid inventories as a means of reducing the specific radioactivity of the liquid. This could provide significant benefits in dose management of the work force. Further, by appropriate chemical treatment, it may be possible to reduce the impact on the environment.

Repackaging of the inventory into a safe form to meet all the necessary safety requirements is likely to be necessary. Interim storage is likely to be adopted in most countries where the approach for long-term storage, e. g. in a repository, has yet to be agreed.

Decommissioning safety risk is primarily associated with risks associated with public health and safety and the risks associated with waste management (de la Ferte, 1996). All OECD countries with nuclear programmes have in place decommissioning regulations, either as part of their general legal infrastructures for nuclear plant licensing or specifically for decommissioning. The IAEA have also set down the general principles to be followed, and defined the respective responsibilities for regulator and operator.

National licensing procedures define whether the operator or public authorities are empowered to decide on shut down and decommissioning of facilities. There are some differences between countries in terms of responsibilities. In the UK and Germany, the responsibilities for the shut down and decommissioning of facilities lies solely with the operator under normal circumstances (Willby, 1996). In other countries such as France, the operator has less independence. There have also been instances where governments have taken a political decision to shut down plant as in the moratoria imposed by Italy and Sweden. The body that has the responsibility for decommissioning operations is also different in different countries, in Canada for example, it is the operator; in Belgium and Spain there is a specialised public agency responsible for radioactive waste management.

In the UK, the HSE has set down policy issues and broad requirements on the licensee (Bacon, 1997). These cover requirements on the licensee in regard to defining strategic plans, work plans, and schedules and priorities for the progressive reduction of hazards (Walkden and Taylor, 2002). These requirements are summarised in Table 6.6.

EC legislation exists to control the environmental impact of decommissioning activities (Nash and Woollam, 2002; Statutory Instrument No. 2892, 1999). This requires the provision by the operator of an environmental statement to support decommissioning activities. UK regulations have a similar requirement.

In general, operations must be managed to ensure that any hazardous releases are prevented as far as is reasonably practicable. Any plant conditions that have a potential for uncontrolled releases must be dealt with as soon as possible. Any discharges that do occur must be within agreed limits. If a potential to exceed these limits is recognised, e. g. prior to defuelling, then early decommissioning may be necessary (Twidale, 1999), or authorisations may have to be renegotiated.