EDF has also entered into a second type of generation allocation contract for a fleet of power plants (totalling some 2GW). While the duration of the agreement and the contribution to overheads remain linked to clearly identified units within the fleet, the total amount of power sold at the variable cost of the fuel is determined by the availability of a broader baseline fleet of power plants, applied to the share of capacity assigned to the co-contracting parties for the units in question. These contracts mainly concern the following power plants:
In these two transactions, the partners have shared with EDF the industrial risks in the development of the fleet and assume the risks linked to the current operation of the power plants. On the other hand, they have no operational role.
Nuclear power is a means of generation whose variable cost, mainly fuel-related costs, is low since it represents less than 30% of operating costs (1). The main competitive levers of the nuclear fleet in its operating phase are thus the amount of generated energy and the optimisation of fixed operating and maintenance costs. The levers relating to the fuel cycle are described in section 1.4.1.1.2.3.
EDF must reconcile the challenges linked to the strong variations in seasonal consumption in France, due to its strong temperature sensitivity, and the availability of maintenance resources together with an efficient use of reactor fuel. Therefore, EDF has adopted 12 and 18 months generation cycles for its fleet, which break down as follows at end-2022:
| Series | Number of units | Generation cycle time |
|---|---|---|
| 900MW | 900MW Number of units28 |
900MW Generation cycle timeApprox. 12 months |
| 900MW | 900MW Number of units4 |
900MW Generation cycle time
|
| 1,300MW | 1,300MW Number of units20 |
1,300MW Generation cycle timeApprox. 18 months |
| 1,450MW (N4) | 1,450MW (N4) Number of units4 |
1,450MW (N4) Generation cycle time
|
At the end of these operating cycles, shutdown periods are programmed in order to replace a fraction of the fuel loaded in the core and perform maintenance work. Two types of planned outages are alternated at the end of each generation cycle:
Every ten years, the power plant is shut down for an average period of 180 days (3) in average to carry out a ten-year inspection (4). This length of time varies according to the works and maintenance programme, as well as the series concerned.
The programme for a ten-year inspection includes the following:
At the end of each ten-year inspection, the ASN has to agree to the restarting of the reactor and make any relevant technical recommendations.
Regulatory notice
The Autorité de sûreté nucléaire (ASN) is an independent administrative authority which contributes to the control of nuclear safety, radiation protection in France, and informing the public about these matters.
Its activity is organised around the following missions:
Nuclear generation resources, owing to their low variable cost are first used for base-load generation, immediately after run-of-river hydro-power and other unavoidable renewable energies, as well as the energy purchased under buying obligations from decentralised energy producers. Variations in energy consumption over one year (summer-winter, day-night) and the currently restricted fluidity of wholesale markets due to limited interconnections on the borders lead nuclear energy to be used also for mid-merit generation. High variations in seasonal consumption in France and its major variation during winter months require that planned nuclear fleet outages be concentrated between April and October.
Nuclear output stood at 279TWh in 2022, a decrease of 81.7TWh from 2021. This decrease is due mainly to the nuclear fleet being less available as a result of the phenomenon of stress corrosion. Following the discovery of this phenomenon in late 2021, several unscheduled outages and extensions of maintenance outages were required to understand it, define a treatment strategy, and commence repair works.
In respect of unit outages, generation losses due to extensions of unit outages for reasons other than CSC amounted to 5TWh less in 2022 than in the previous year.
Among the completed shutdowns, the following were on schedule or shorter than forecast: Chinon B4 (Partial Inspection, VP), Tricastin 2 (Simple Reload Shutdown, SRS), Cruas 1 (SRS), Nogent 1 (VP), Saint-Laurent B1 (SRS), Tricastin 4 (VP), Belleville 2 (VP) and Tricastin 1 (SRS). Of particular note is the performance at Tricastin 4 (32.8 days ahead of schedule), Nogent 1 (27.4 days ahead of schedule) and Chinon B4 (12.7 days ahead of schedule).
The Saint-Laurent B1 shutdown recorded the site’s best performance in 10 years; the Partial Inspection (VP) of Belleville 2 was the shortest in 6 years. Performance on these two sites illustrates the effects of the START 2025 plan currently being rolled out across the nuclear fleet. The plan focuses on improving performance of unit shutdowns and enables sites suffering from long-term difficulties to improve their performance.
(1) Operating costs are defined as follows: fuel costs (including downstream expenses in the fuel cycle), operating expenses (purchases and external services, employee expenses) and maintenance costs (expenses and investments). They do not include investments related to construction or decommissioning expenses.
(2) Standard durations represent optimised and realistic reference durations by outage types. They take into account the feedback from past.
(3) “Normal” duration excluding particular and/or extreme cases.
(4) Pursuant to Article 593-18 of the Environmental Code.
