The main objective of the three projects of the BA agreement is to provide additional information on the areas of ItER physics and technology needed for DEMO, the next step in fusion energy research. The activities provided for in the BA Agreement must be carried out within a period compatible with the construction phase of ITER and the Agreement shall remain in force for a period of ten years and shall remain in force thereafter, unless it is denounced by either Party. In this way, the three projects of the broader approach constitute a well-integrated approach to support the ongoing merger programme, focused on ITER, and prepare the technical planning and construction of DEMO. The need for a neutron source for research on fusion materials was recognized as early as the 70s. The current state of the five technological challenges, perceived in the past as the most critical, is discussed. These will include: 1) the feasibility of IFMIF accelerators, 2) the long-term stability of the lithium flux under IFMIF nominal conditions, 3) the potential instabilities in the lithium screen induced by the dutron beam of 2 × 5 MW, 4) the uniformity of temperature in the samples during irradiation and 5) the validity of the data provided with small samples. Other ideas for testing melting materials have been considered, but they may be technologically unfeasible if fixed objectives are taken into account, or would require a reliable interpretation of the results of a Li (d,xn) installation. In addition, we now know beyond a reasonable doubt that the cost of IFMIF, estimated consistently for decades, is marginal compared to the cost of a fusion reactor. The less ambitious power of the DEMO reactors envisaged is correlated with a lower need for flows of new fusion neurons; thus, the IFMF with its two accelerators might not be necessary, as a single accelerator, as proposed by the European DONES or the Japanese A-SNSF, would meet the current needs > 10 dpa/fpy.
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