France's EDF is using the latest data from operational reactors and ongoing dismantling work to standardize processes and optimize multi-site decommissioning, Frederic Magloire, Chief Technical Officer of EDF’s Chooz A project, said.

EDF's 58 French nuclear power reactors are situated on 19 sites and they provide around three quarters of the country's power. A new “energy transition” law plans to reduce the share of nuclear power to around 50% of generation by 2025.

State-controlled EDF has been carrying out a fleet-wide standardization project which will provide annual updates of decommissioning cost estimates and benchmarks, to highlight opportunities for multiple-site synergies, Magloire said at Nuclear Energy Insider's Nuclear Decommissioning Conference Europe on May 31.

In one example, a steam generator replacement program across the operational nuclear fleet has provided EDF with "technical" and "financial" data that will help to optimize decommissioning tasks, Magloire said. The steam generator replacement program saw productivity gains of up to 40% between the first of kind implementation and the fleet-wide series roll-out, he said.

"We think these kind of large operations are very close to [Reactor Pressure Vessel] dismantling, because you use the same tools, you use very [similar] techniques- there is very little difference from one site to another," Magloire said.

EDF has the advantage of being engineer-architect for its nuclear plants, allowing it to access expertise from the design, construction, operation and decommissioning phase of the reactors.

Earlier this year, the company merged its waste and decommissioning activities into a single Decommissioning and Waste Management business division which reports directly to the EDF executive committee, allowing for swifter decision-making.

Equipment gains

France's nuclear power plant fleet consists of pressurized water reactors (PWRs) of capacities 900 MW, 1.3 GW and 1.5 GW, commissioned in different "generations" from 1967 onwards.

The decommissioning of the first-generation 305 MW Chooz A plant, shut down in 1991, represents the first PWR dismantling to take place in France. EDF is continuing to gather valuable data from the decommissioning work at the Chooz site in the north-east of the country and it will use this knowledge to optimize the upcoming decommissioning of second generation reactors and leverage synergies for the wider fleet strategy.

The French government's plan to reduce the share of nuclear power is to start with the closure of two 900 MW second-generation reactors at the Fessenheim nuclear power complex by around 2018.

EDF expects gains from the standardization of equipment across multiple sites as it starts to flesh out its decommissioning strategy in the coming years, Magloire told conference attendees.

The operator is currently installing new equipment at Chooz A for reactor pressure vessel dismantling, including sawing equipment for internal vessel work which was tested in Sweden in 2015, Magloire said.

"That's an example of how we prepare...we are very confident because we saw that it is very robust...and very efficient and very easy to maintain and to replace," he said.

Faster progress

The Chooz A plant started operations in 1967 and was stopped in 1991, before EDF shifted in 2001 to a strategy of immediate decommissioning upon closure. French regulations delayed EDF from performing some of the major decommissioning work until a new decree was implemented in 2007. EDF plans to carry out vessel dismantling work at Chooz A until around 2020 and plans cleaning up operations at the site from 2020, some 30 years after the plant was shut down.

In comparison, EDF aims to complete the decommissioning of the second generation Fessenheim reactors in "around five years," Magloire said.

EDF has been able to prepare for the immediate decommissioning of the Fessenheim plant and, unlike the first-generation Chooz A plant, staff currently employed at the Fessenheim plant will be able to transfer operational expertise directly into the closure phase, he said.

"They know the power plant, it's very important to have the knowledge of the power plant... Many things are written [down] but you have lots of things which are not written," he said.

The decommissioning of Chooz A has highlighted the importance of integrating the two constraints of waste and transport into decommissioning projects, Magloire noted.

The project has also shown how operators must monitor the period between end of generation and start of dismantling, including the radiological and physical inventory, support functions and rinsing of main circuits, he said.

Nuclear Energy Insider