In general, the IAEA Study (IAEA-TECDOC-1084, 1999) found that the variations and uncertainties found in the data (costs levelised to 1997) for decommissioning after long­term storage (Table 6.7) had similarities with the data for decommissioning immediately (Table 6.8). In particular, this correspondence related to variations from country to country and also from specific case to case. Also not surprisingly, decommissioning costs were sensitive to national labour resource estimates.

6.11.1.1 PWRs. Estimates were provided for reactors from Belgium, Germany, Japan, Korea, Netherlands and the US for units in the range 500-1300 MWe. It was found that costs ranged between 200 and 700$US per kWe, and for the capacity range considered there were no economies of scale. It was found that in most cases the total over-night costs for decommissioning with long-term storage were higher than for immediate decommissioning, considered later. However, it is recognised that the net present value would normally be on the contrary, dependent on the decommissioning schedule and the assumed discount rate.

6.11.1.2 BWRs. Estimates were provided and shown for Finland, Germany, Italy, Japan, Netherlands and the US for reactors in the range 160-1300 MWe. Decommission­ing costs were found to be in the range 150-600$US per kWe (a small BWR-60 plant in

the Netherlands was also analysed; it was found that scaling effects did exist for the smaller capacity plant). In addition, the relative costs between decommissioning after long-term storage and immediate decommissioning were similar to those for PWRs. For example, long-term storage undiscounted costs were again higher than immediate decommissioning but as noted earlier, the situation would be different if discounted costs are taken into account.

6.11.1.3 VVERs. Data were available from Bulgaria, Czech Republic, Germany, Russia and Slovakia. Reactors considered were the VVER 440 MWe plants 440/230 and 440/213. The costs were found to differ widely from 120 to 130$US per kWe in the Russian Federation up to 1400$US per kWe in Germany. Much of this difference is reflected in labour rate costs. As for PWRs and BWRs, decommissioning with long-term storage is more expensive than immediate dismantling (undiscounted costs). The differences were relatively small for Slovakia.

6.11.1.4 HWRs. Decommissioning costs from three available assessments of Canadian units were estimated. It was found that there was a substantial difference between units of similar capacity, largely reflecting the situation that the cost estimates were made at different times. For some Canadian plants, decommissioning with long-term storage was found to be cheaper than decommissioning with immediate dismantling even in undiscounted costs.

6.11.1.5 LWGRs (RBMK). Estimates were available from the Ukraine and Russia. Due to the large amount of graphite in the core, decommissioning with long-term storage is a more feasible option for LWGRs than decommissioning with immediate dismantling. Most assessments for long-term storage are again higher (undiscounted) than those for immediate dismantling.

6.11.1.6 GCR and AGRs. Gas-cooled reactor data were supplied from the UK and for an old reactor in Spain, results are shown for the range 200-660 MWe. Due to technical design reasons, decommissioning with long-term storage is preferable to immediate dismantling. This is because there are some operations that can be carried out manually that are not possible for PWRs and BWRs. The costs for GCRs are higher than for other reactor types 1000-3000$US per kWe for the above capacity range. Part of the reason is not only due to the smaller size of GCR units but also there are larger volumes of radioactive waste that need to be processed. There are also increased man-power requirements.

6.11.1 Immediate Dismantling

Immediate dismantling decommissioning costs are summarised in Section 6.11.2, for the major reactor types of interest (IAEA-TECDOC-1084, 1999).

6.11.2.1 PWRs. Data were collected from a number of countries including Belgium, France, Korea, Netherlands, Sweden, UK and the US. A range of plants was considered covering the range 500-1400 MWe. The costs spanned between 150 and 700$US per kWe, reflecting large deviations in the key decommissioning parameters across the countries considered. These related particularly to differences in labour requirements, on the amount of decommissioning wastes and the duration of decommissioning activities. In general, it was found that the effect on reactor scale was small compared with differences between countries and differences between the estimates for the same reactor made at different times.

6.11.2.2 BWRs. Estimates were considered for Finland, Germany, Japan, Nether­lands, Sweden and the US, covering reactor units in the range 470-1300 MWe. Decommissioning costs were found to be in the range 170-650$US per kWe, i. e. similar to those for the PWRs (the effects of scale, however, were more visible than for BWRs), but again these were small compared with cross country variations of estimates with time.

6.11.2.3 VVERs. VVER plants have certain design differences from PWRs which impact on decommissioning costs, e. g. there is a high share of common systems and components in twin units.

In IAEA-TECDOC-1084 (1999), costs were presented for Bulgaria, Finland, Germany, Russia and for Slovakia for largely 440 MWe units of the 230 and 213 specification.

In general, the costs for VVERs were similar to those for PWRs and BWRs, except in Germany and Russia. Costs were higher in Germany and lower in Russia. These differences were not quantified but differences in labour rates and also in labour requirements were contributing factors.

6.11.2.4 HWRs. Data were available from Canada, Korea and India covering plants in the range 200-1300 MWe. In general, costs for HWRs are of the same order as for PWRs, BWRs and VVERs, but the cost variation from case to case appears less. However, the sample of plants considered was smaller. The costs for Korea were higher than Canada and India.

6.11.2.5 LWGRs (RBMK). Estimates were considered from Lithuania (1500 MWe Ignalina NPP) and Russia (1000 MWe plants). In general, assessments for LWGRs are lower than for other types, almost certainly reflecting low labour rates in these countries. The estimates were higher in Russia than in Lithuania; however, in the Russian data the costs of handling irradiated graphite were not included. In the Lithuanian data, these costs were taken into account.

Practically all the costs above were derived on the assumption of planned decommissioning. There may be cases when decommissioning is required urgently. This might be due to economic, safety, political or social reasons. In such cases, additional financial losses may be incurred (IAEA-TECDOC-1084, 1999).