Paris (Platts)--20Jan2011/600 am EST/1100 GMT

France's naval construction firm DCNS has agreed with Areva, EDF and the CEA R&D organization on a joint study of DCNS' concept for a submerged nuclear power plant unit that its promoters say could provide energy for millions of people in coastal locations worldwide.

The technical, economic and market feasibility study will be conducted over the next two years by 100-150 people from DCNS and the nuclear organizations, after which a decision could be made to build a prototype, DCNS Chairman and CEO Patrick Boissier said Wednesday.

The concept, called FlexBlue, involves a cylindrical vessel about 100 meters long and 15 meters in diameter that would encase a complete nuclear power plant with an electrical capacity of between 50 MW and 250 MW, Boissier said in an interview in his Paris office.

The cylinder with the power plant inside would be lowered to the seabed at a depth of 60 meters (196 feet) to 100 meters, at a site between five and 15 kilometers from the coast. Undersea cables would bring the electricity to customers on shore.

Boissier said that three-quarters of the world's population lives within 80 km of the sea.

Russian industry has already developed the design for a floating nuclear power plant which uses two 70-MW reactors derived from those used in Russian submarines and icebreakers; a prototype was launched last year. But Boissier said a submerged power plant, unlike a floating one, would not be vulnerable to earthquakes, tsunamis, or floods, and would be far less vulnerable to voluntary attack.

It would also have an "unlimited" source of coolant from the surrounding sea, he said, and the plant's "environmental footprint would be minimal."

Boissier said FlexBlue is designed to the highest modern safety standards, commensurate with those of so-called third-generation nuclear plants designed by Areva and its competitors.

The cylindrical vessel concept obviates the need for civil engineering -- which has proved challenging at Areva's and EDF's ongoing nuclear power plant construction projects in Finland and France -- and means the plant can be built in factory in a modular way with standardized components.

If a problem developed with the reactor, it could be brought to the surface and taken to DCNS' shipyard in Cherbourg for repair, Boissier said.

It could be refueled in the same way, and at end of life would be repatriated to the shipyards for decommissioning, which would resemble decommissioning of nuclear submarines, which DCNS has already done, he said.

Areva has already begun developing a small modular reactor, or SMR, of about 100 MW, based on the experience of its Technicatome unit in building reactor plants for submarines and France's nuclear-power aircraft carrier, the Charles De Gaulle. Such a reactor could be embarked in a FlexBlue power plant, Boissier said.

Boissier said the market for SMRs is estimated at about 200 units worldwide over the next 20 years. "Flexblue could take a significant share" of that market, he said, but declined to define what he meant by significant.

He said the study will determine how much a FlexBlue plant would cost and what would be the price of electricity it produced, but added "preliminary studies show that we should be compatible with the cost of renewable energies, and better than solar power."

DCNS' shareholders are the French state (74%), defense firm Thales (25%), and employees (1%).

--Ann MacLachlan, ann_maclachlan@platts.com

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