La France nucleaire/Nuclear France: PROVENCE-ALPES-COTE D'AZUR (ENGLISH)

Nuclear France: materials and sites

By Mary Byrd Davis

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PROVENCE-ALPES-COTE-D’AZUR

CENTRE DE CADARACHE (CEA-CADARACHE)

RESEARCH ON FUSION

In a fusion reaction the nuclei of two light elements fuse to form a nucleus that is heavier than either. The fusion of nuclei of deuterium and/or tritium, isotopes of hydrogen, forms helium while releasing neutrons and energy. This is the most feasible fusion reaction [CEAIter 05]. Fusion occurs spontaneously in the sun and the stars. On earth one kind of fusion, inertial confinement fusion, is used in nuclear weapons development; another, magnetic confinement fusion, is a potential source of electricity. (These forms of fusion are controlled. Uncontrolled fusion takes place in boosted nuclear and thermonuclear weapons.) In the sun and stars gravitational pressure makes possible fusion at about 10 million degrees Celsius. On earth, where pressure is less, the temperature has to be more than 1000 million degrees Celsius.

In a tokamak, fusion occurs in an electrically charged gas called a plasma. Plasmas are created by breaking down atoms of the light elements involved into electrons and atomic nuclei. For fusion to occur, the nuclei must be forced together at high temperature. The plasma is held in place by magnetic fields.

TORE SUPRA--in operation

Type: tokamak

Operator: CEA in association with Euratom

Period of operation: 1988-

Nuclear material: deuterium

Comments: the first tokamak with super-conductor magnets

With a plasma volume of 30 m3 and a large plasma radius of 2.40 m, Tore Supra is the world's largest superconducting tokamak. Its superconducting toroidal magnets generate a permanent toroidal magnetic field. In 2003 Tore Supra succeeded in creating a plasma with an energy of 1000 MJ for more than six minutes [CEA 29.vi.05].

ITER (INTERNATIONAL THERMONUCLEAR EXPERIMENTAL REACTOR)--under construction

Purpose: demonstrate the scientific and technical feasibility of fusion as a source of energy

Type: tokamak

Location: 181 ha site adjacent to CEN Cadarache and within a 1600 ha forest

Operator: ITER Organization

Period of operation: ?

Nuclear materials: tritium, deuterium, lithium

Nominal capacity: goal of 500 MW

The European Union, China, India, Japan, Russia, South Korea, and the United States are partners in Iter (International Thermonuclear Experimental Reactor), a tokamak that will be bigger and more advanced technologically than Tore Supra and Jet (a Euratom project, located in England). The main site of Iter will be at Cadarache, the partners decided in June 2005. Japan had fought long and hard to host the reactor and received major concessions in return for conceding this point, including 20% of the staff positions and the position of director..

Construction of ITER, which will be composed of the key installation the Tokamak Hall and seventeen support buildings [Rosanvallon 07], was originally estimated to require ten years. Approximately half of the 181-ha site has been cleared of trees to allow construction. A 400 m by 1000 m platform, totaling some 42 hectares was completed in April 2009.

Components are being made at facilities in member states. The parts will be shipped to Fos-sur-Mer, where they will be unloaded. They will then be taken by barge across the Etang de Berre, and carried by truck to the ITER site. As the crow flies, Fos is only 50 km from ITER, but the route taken will be indirect and the components will travel 106 km across land. A single component may be as much as 45 m long, 9 m high, 7 m wide, and several hundred t in weight. Therefore, in the words of the Conseil général des Bouches-du-Rhône, "It will be necessary to reinforce, widen, destroy, or build other bridges." The itinerary uses existing roads for the most part, but many of these needed to be widened [Rosanvallon 07]. By early 2010, 90% of the itinerary had been completed.

Iter will operate for an estimated twenty years. In the tokemak's early years, hydrogen and deuterium plasmas will be studied. Then scientists will use a combination of deuterium and tritium to try to meet two goals: producing 500 MW, while only drawing on 50 MW, for more than six minutes; and showing that fusion reactions in plasma can be made to continue for more than sixteen consecutive minutes [CEA 29.vi.05].

Potentially tokemaks can produce their own tritium from lithium while in operation. For Iter the tritium will have to be introduced from outside. However, an aim of the research is to work out a methodology for tritium production within a tokemak. The intention is to surround the plasma with a blanket of lithium that absorbs energy from the neutrons that bombard it and breeds tritium fuel. There are plans to irradiate samples of materials for the surrounding blanket, but not to test actual blankets. According to Steve Cowley of the U.K., without tests of the blanket, the date when fusion can create useful energy cannot be calculated [Cowley 09].

In November 2009 the Iter Council agreed on the need to revise the schedule for Iter. A revised schedule is expected to be released by the end of February 2010.

As of early 2010, the total cost of constructing and operating Iter was estimated to be $10 billion euros [http://www.iter.org]. The cost is to be shared amount members.

Estimated Waste

--A total of 1600-3800 t of housekeeping and process wastes from the twenty years of operation, of which 20% will be "very weakly" radioactive, 75% will have low or intermediate radioactivity, and 5% long-lived, intermediate-level radioactivity;

--About 750 t of components that have been replaced. They will have long-lived intermediate radioactivity;

--About 30,000 t of waste from the decomissioning (60% will be "very weakly" radioactive, 30% will have short-lived or intermediate-level radioactivity, and 10% long-lived intermediate-level radioactivity [Rosanvallon et al. 07].