As construction nears for the International Thermonuclear Experimental Reactor (Iter), another contract for the supply of components has been signed and production of wire for the fusion reactor's toroidal field magnets has begun.
|A cutaway of the Iter fusion reactor (Image: Iter Organization)
Russia's Kurchatov Institute has signed a contract with the Iter Organization for the supply of ports and diverting systems fusion reactor. Vacuum vessel ports are used for installation of diagnostic and heating equipment, vacuum pumping and access to the vessel during operation. The vacuum vessel will have a total of 44 ports: 18 upper ports, 17 equatorial ports, and 9 lower ports.
The vacuum vessel of Iter is a steel container inside the cryostat that houses the fusion reaction and acts as a first safety containment barrier. It will be twice as large and sixteen times as heavy as any previous tokamak, with an internal diameter of six metres. It will measure a little over 19 metres across by 11 metres high, and weigh in excess of 5000 tons.
Diverting systems directly contact with plasma and protect Iter systems. They will be water-cooled structures, made of copper alloy and steel, coated with tungsten.
Extremely powerful superconducting magnets will be used to maintain the fusion plasma equilibrium and shape inside Iter and South Korea's Kiswire Advanced Technology (KAT) has started production of 28 tonnes of niobium-tin (Nb3Sn) wire for Iter's toroidal field magnets.
The company has already produced 800 kg of wire using in-stock raw materials and is now in the process of carrying out acceptance tests as required by the procurement arrangement.
Korea is responsible for manufacturing 20% of the cable-in-conduit conductors for Iter's toroidal field coils. This represents a total of 20 kilometres of superconducting cable made out of 90 tonnes of Nb3Sn stands.
In October 2008, the Iter Organization signed the first of three procurement arrangements for main components for the tokamak's poloidal field (PF) conductors with China's domestic agency for nuclear fusion.
The manufacturing of the PF coils is being divided between China, Russia and Europe, with China contributing 67%, some 45.4 km of cable. Russia will produce 19.7% (10.7 km) with Europe providing the remaining 13.3% (8.6 km). The PF coils are one of four main subsystems making up Iter's superconducting magnet system. The PF coil system itself consists of six independent coils, made of two types of twisted, multifilament nickel-plated niobium-titanium based composite strands. A prototype coil for the PF system performed to design specification in recent tests hailed as a technological milestone for the project.
Seven parties - China, India, Japan, Russia, South Korea and the European Union - are cooperating to build Iter, a 500 MWt tokamak, at Cadarache. The partners agreed in mid 2005 to site Iter at Cadarache. The deal involved major concessions to Japan, which had put forward Rokkasho as a preferred site. The EU and France will contribute half of the €12.8 billion ($18.7 billion) total cost, with the other partners - Japan, China, South Korea, USA and Russia - putting in 10% each.
Site preparation at Cadarache in began in January 2007 and construction is due to begin later in 2009, with operation around 2018. As part of the reactor's phased commissioning, it will initially be tested using hydrogen. Experiments using tritium and deuterium as fuel will begin in 2026.