The ITER Test Blanket Working Group (TBWG) was re-established in September 2003 and convened for the third time at EFDA Garching (Germany) from 7 to 9 July 2004. Four members of the ITER International Team and up to three members from each of the ITER Participants (China, EU, Japan, Russian Federation, South Korea, USA) contribute to the group. The main mission of the TBWG is to develop the Design Description Document for the Test Blanket Modules (TBMs) proposed by the participants, to promote collaborations in R&D and sharing of common TBM features and to define a coordinated TBM test schedule for the first 10 years of ITER operation.

Three horizontal ports of the ITER machine are reserved for the installation of DEMOrelevant TBMs capable of achieving sufficiently high tritium breeding ratios and thermal efficiencies for electricity production. The six ITER Participant Teams are proposing different types of breeding blanket concepts for the TBMs such as He-cooled or water-cooled ceramic/ Be, He-cooled or dual cooled LiPb, self cooled Li concepts, etc. ITER will supply unique testing conditions for the TBMs under fusion-relevant conditions, although, due to the low neutron fluence, long-term irradiation damage in the materials cannot be addressed. It will be a big challenge to install the different types of TBMs in ITER in an integrated and harmonised way due to the limited available space in the ports and in the building. All the proposed TBMs have to pass stringent qualifications and acceptance tests before installation in order not to jeopardise the operation of ITER.