Extending the lifetime of Belgian nuclear power plants to 20 years can save €200 million. Per year.
The 10-year lifetime extension of Doel 4 and Tihange 3 comes with a strike price of ~€90/MWh. That’s significantly higher than many expected — and even higher than what you’d get if you simply inflation-adjusted the €42/MWh reference price used for the previous Tihange 1 extension (which would result in ~55 €/MWh).
It turns out that the main reason for this surprisingly high price is not only the investment and operational cost, but also the production losses during the lifetime-extension (LTO) works during the first three years.
Why the LCOE is so high for the 10 year extension
According to the European Commission’s consultation file (OJ C 2024/4921), during the first three years of the 10 year LTO-period, both reactors will be offline for 24 weeks for the LTO works, plus 6 weeks for scheduled non-LTO outages. On top of this, a 10% unplanned unavailability is assumed.
If we assume:
Investment cost: €900 million per unit (midpoint Engie’s communication)
Return (IRR): 7%
Cost structure: based on inflation-adjusted CREG data for fixed and variable OPEX to 2025 euros (936 M€ of fixed opex for four units and 11.35 €/MWh of operational costs, in 2022 euros - see page 5 of CREG decision 2555)
Expected generation: as published in the EC’s consultation file: 3.435 GWh for the first 3 years and 7.17 GWh for the next 7 years
then a simple discounted cash-flow (DCF) model yields a levelised cost of electricity (LCOE) of ≈ €85/MWh for the 10-year extension.
That number aligns well with the announced strike price of €90/MWh and helps explain why it’s so high.
What happens if the lifetime doubles from 10 to 20 years
If, instead of 10 years, the same investment costs and the unavailability due to the LTO-works are spread over 20 years, the picture changes completely.
The LCOE drops to roughly €70/MWh, a reduction of ~€15/MWh (on the condition there are no major investment needed after 10 years).
That translates to annual savings of more than €200 million:
14.2 TWh × €15/MWh = ~€213 million per year
And this doesn’t even account for the added energy supply that decreases electricity prices and grid-stability benefits of keeping 2 GW of low-carbon baseload online longer.
Small operational optimisation, big impact
If the scheduled 6-week non-LTO outage could coincide with the LTO works, increasing generation during the first 3 years, the cost efficiency improves further:
10-year LTO: LCOE decreases from €85 → < €79/MWh
20-year LTO: LCOE decreases from €70 → ≈ €67/MWh
That alone would save another €45-85 million annually.
The total impact of a lifetime extension of 20 years instead of 10 years combined with the overlap of the planned 6 weeks unavailability and the 24 weeks unavailability for LTO is then 18 €/MWh, which results in a saving of €250 million annually
This also shows that extending the lifetime of existing nuclear power plants is the only technology we know of that can meet the energy trilemma: deliver reliable, climate-neutral and affordable energy.
A note of caution
All LCOE values are based on public data from CREG and Engie.
It’s quite possible that the actual costs are significantly lower — Engie has every incentive to present the highest possible cost base when negotiating with the government.