Universal Registration Document 2021

Details of changes in decommissioning provisions for nuclear power plants are as follows:

Other movements in provisions for decommissioning nuclear plants in operation include the impact of extension of the depreciation period for 1300MW-series plants, which is partly offset by the effects of the change in the real discount rate at 31 December 2021.

For nuclear power plants currently in operation (PWR pressurized water reactor plants with 900MW, 1,300MW and N4 reactors)

Until 2013, provisions were estimated based on a 1991 study by the French Ministry of Trade and Industry, which set an estimated benchmark cost for decommissioning expressed in €/MW, confirming the assumptions defined in 1979 by the PEON Commission. These estimates had been confirmed from 2009 by a detailed study of decommissioning costs conducted by EDF at the representative site of Dampierre (four 900MW units), and its results were corroborated by an intercomparison with the study carried out by consultants La Guardia, based mainly on the Maine Yankee reactor in the US.

In 2014 the Dampierre study was reviewed by EDF to make sure that the previous calculations were still valid in view of recent developments and experience, both internationally and internally. For this revision, the decommissioning provisions for plants in operation were based on costs resulting from the Dampierre study, in order to incorporate best estimates and experience from inside and outside France. This change of estimate had no significant impact on the level of provisions at 31 December 2014.

Between June 2014 and July 2015, an audit of dismantling costs for EDF’s nuclear fleet currently in operation was conducted by specialised consulting firms, at the request of the French Department for Energy and Climate (Direction Générale de l’Énergie et du Climat or DGEC). On 15 January 2016 the DGEC published a summary of the audit report. It stated that although estimating the cost of decommissioning nuclear reactors is a demanding exercise due to relatively limited past experience, the prospects of changes in techniques, and the distant timing of the expenditure, overall, the audit confirmed EDF’s estimate of decommissioning costs for its nuclear fleet currently in operation. The DGEC also made a number of recommendations to EDF following this audit.

In 2016, EDF revised the decommissioning estimate, in order to incorporate the audit recommendations and past experience gained from dismantling operations for first-generation reactors (particularly Chooz A).

A detailed analytical approach was used to revise this estimate, identifying all costs for the engineering, construction work, operation and waste processing involved in future decommissioning of reactors currently in operation. This led to figures based on detailed timetables for plant decommissioning. The approach adopted made it possible to explore more thoroughly the assessment of costs specific to the initial units of each series, estimated for each series based on transposition coefficients applied to the baseline costs for the initial 900MW unit, and the series and mutualisation effects, as these costs and effects are inherent to the fleet’s size and configuration.

The natures of the principal series and mutualisation effects used to arrive at the estimate are explained below.

Series effects (effects of work for the first-of-a-kind site on the following sites of the same series) are mainly of two types:

• first, in a fleet using the same technology, many of the studies do not need to be repeated each time;
• second, in a fleet using the same technology, robots and tooling can be largely reused from one site to another.

Mutualisation effects (effects between units in the same site, whether in operation or being decommissioned) are of several different types:

• some of them relate to the fact that several reactors may share common buildings and facilities on the same site, and these buildings and facilities will not have to be dismantled twice;
• certain costs are not higher when two or four reactors are dismantled on the same site. This is usually the case for surveillance costs, common equipment, and the cost of maintaining safe operating conditions on the site.

Due to mutualisation effects, dismantling a pair of reactors on the same site costs less than dismantling two standalone reactors on two different sites. In France, unlike other countries, there are no single reactors but sites with two or four, and in one case six reactors.

Series and mutualisation effects reduce the estimated decommissioning cost by 10% and 6% respectively compared to an estimate that ignores these effects. Series and mutualisation effects vary depending on the series: they are greater when there are more units in a series (series effect) and more units on a site (mutualisation effect), leading to a combined effect (series and mutualisation effect) of over 16% for the 900MW series.

In particular, series and mutualisation effects explain why it is not appropriate simply to compare the average dismantling cost per reactor between the French fleet and other countries’ nuclear fleets.

In contrast, the estimates only marginally reflect changes in productivity and the learning effect. The external audit of the decommissioning cost for the fleet currently in operation, ordered by the DGEC, considered that this approach resulted in a prudent estimation method.

For reasons of prudence, the estimate also includes an assessment of risks and uncertainties as follows:

• incorporation of uncertainties relating to each “elementary” block of costs, series effects, mutualisation effects, transposition coefficients and fleet expenses;
• incorporation of risks, corresponding to the completion risks (which are identifiable and quantifiable, but only contingent). An initial register of risks on the Fessenheim project was drawn up in 2021 based on the ongoing studies, and detailed assessment of these risks is continuing for one first-of-a-kind 900MW reactor on the Fessenheim site that has no specificities. Until the results are released, the financial impact of the risks and opportunities is included via a flat-rate increase.

The above method for assessing risks and uncertainties leads to an overall margin of some 15.7% for the whole fleet (19.5% for the first 900MW unit).

Since its in-depth revision in 2016 this cost estimate has been reviewed annually. The reviews have led to non-significant annual adjustments.

In 2021, to take account of the impacts of the longer depreciation period for 1300MW-series plants, the sequence of operations for dispatching waste from decommissioning was adapted to reflect the increase in decommissioning waste to be sent for interim storage in certain years.

Also, the reference cost for decommissioning of the first 900MW units was updated following preliminary studies conducted in preparation for the decommissioning of Fessenheim, and experience gained at the beginning of the pre-dismantling phase. This update also incorporates optimisation of the industrial scenario for management of decommissioning waste before storage, involving prior processing to reduce the volumes stored. Extrapolation of these elements to the whole PWR fleet has a limited impact on the provisions for decommissioning nuclear plants in operation: they are increased by €149 million via adjustment to balance sheet assets.