ITER International Thermonuclear Experimental Reactor

To harness this source of energy on our Earth is very laborious!

The idea to use the fusion of hydrogen into helium as an energy source originated first in the 1950s. At around the same time, scientists from the United States and the USSR developed concepts to capture a plasma of deuterium and tritium in a magnetic field. The particles are confined in closed orbits by using combined toroidal and a poloidal fields. At temperatures of 150 million Kelvin - ten times hotter than inside of the Sun - helium is produced by nuclear fusion. This energy is set free and could drive a steam turbine to generate electric power. The unstable tritium fuel will be created directly in the fusion reactor from lithium.1

Calculations show that the deuterium in a bathtub full of water and the lithium from a laptop battery are sufficient to gain enough energy to provide a family with enough power for 50 years.  The technical implementation is extremely challenging and we must find out if it is actually possible with ITER to produce ten times more energy than is needed to heat the plasma.

The production of the ITER plasma vessel (weight ~ 5000 t) is divided into 9 sectors, 7 of which are to be manufactured in Europe by the AMW Consortium (consisting of Ansaldo Nucleare, Mangiarotti and Walter Tosto). AMW has decided to produce the sectors by using pro-beam electron-beam welding.

Each sector specification consists of:

  • A double-walled structure made of 60 mm thick 316LN(IG)
  • Dimensions 11x7m
  • Weight: ~ 450t
  • Tolerance at the sides of the sector < 5mm
  • The vacuum vessel is a complete construction, which is designed for a water cooling system under a pressure of 24 bars

The electron beam fully demonstrates its advantages in the project and convinces with the following properties:

  • extremely high concentration of energy at the focus point of the electron beam and a very high associated power density (100 to 1000 times higher than conventional welding)
  • welding in vacuum produces exceptional purity of the welded joint and minimises weld defects
  • high reproducibility of the seam quality results from automated welding in vacuum with the welding parameters readily and easily electrically adjustable
  • very high welding speeds allow the high power density of the electron beam to be utilised
  • high welding speeds yield high productivity with a relatively low energy consumption
  • due to the high power density of the electron beam, relatively little total energy is introduced into the component, which is then almost distortion-free so that finished machined components can be welded on
  • is possible to weld different materials together