In 1967 a board of inquiry initially laid out plans for two UNGG reactors with an output of 800 MWe each.

Due to falling petroleum prices and conflicts between EDF and CEA, the project was delayed, with a decision made between 1967 and 1969.

In 1969 after the departure of Charles de Gaulle, CEA gave up on the UNGG plans.

In 1973, a nearby hydroelectric plant of 63 MW was completed and the regional manager for EDF announces plans for PWRs at the same site to be finished by 1985.

On 17 June 1979, 5000 protesters walked on the future site and released balloons.