One of the objectives of ITER is to demonstrate fusion technology in an integrated system by performing testing of nuclear components, in particular to test design concepts of tritium breeding blanket relevant to a DEMO reactor. In the current ITER design three large equatorial ports have been allocated for blanket module testing.

Typical testing conditions foreseen now include a surface heat flux of 0.1 MW/m2, a neutron wall load of 0.78 MW/m2, pulse length of 400 s with a duty cycle of 25%. After the first 10 years of operation one may expect to reach a total neutron fluence at the surface of test blanket modules ~ 0.12 Mwy/m2. In the second 10 years of operation very long pulses and accumulation of neutron fluence ~ 0.3 MWy/m2 may be expected.

Test modules must not compromise ITER safety and reliability. Water-cooled modules must have their own pressure suppression system. The mass of liquid lithium is strictly limited to avoid a hydrogen explosion.

Breeding blanket testing in ITER is extremely important for DEMO breeding blanket development. The best effort has to be undertaken to coordinate the Parties' activities in this area and to achieve the best use of space and time available for blanket testing in ITER.