Neutron measurement and diagnostic is of paramount importance in fusion machines like the ITER Tokamak. Indeed the measurement of neutron yield and spectrum as well as that of the tritium production play a key role in determining the plasma conditions where nuclear fusion reactions occur. Among the several neutron detectors needed in ITER those to be located in the Tritium Breeding Module (TBM) are the ones with the most demanding requests since inside TBM the temperature is at least 300 °C and the neutron field is very intense. One important issue to be addressed for these devices is the characterization of their detection performances under long lasting data acquisition at high temperature (T >200 °C). Following the first successful test up to 150 °C, we propose diamond with improved characteristics up to 250 °C under continuous irradiation for one week using the INES diffractometer.