EDF skirted around committing to the Hinkley Point C nuclear power plant in Somerset being finished by 2025.
When asked whether the nuclear power plant will be completed on time, De Rivaz said this is "the date we would like to be able to confirm” but cautioned it will only be set after the final investment decision has been made.
He'd added that the FID would be taken once a non-binding consultation with the French unions had taken place. The unions want Hinkley to be delayed by two to three years, amid concerns over its impact on EDF's balance sheet.
The consultation began on 2 May and will last at least 60 days, however he wouldn't give a definitive end date.
Energy minister, Andrea Leadsom, subsequently said that it wasn't for the UK government to dictate when the FID should be made.
French Economy Minister, Emmanuel Macron, had written to MPs ahead of the committee hearing saying that he had "every confidence" the FID can be made "rapidly" following the union consultation.
"Hinkley Point C is a project whose profitability outlook is positive for EDF, provided its construction costs are kept under control and its risks can be controlled," he said.
There's growing concern over whether the project, which is crucial to the government's energy policy, will go ahead at all. France's energy minister, Ségolène Royal, has questioned whether France should proceed with it, while EDF's chief financial officer Thomas Piquemal resigned due to funding concerns earlier this year.
De Rivaz previously said that the FID would be made "very soon" during his last appearance on 23 March, but it was later pushed back to at least September.
"There's a feeling that the can is being kicked down the road constantly by EDF. People have a right to know one way or the other," Angus Brendan MacNeil, chair of the energy and climate change committee, told City A.M ahead of today's grilling.