Novel neutron activation detector for fusion

Authors:   Stamatelatos I., Savva M., Vasilopoulou T., Triantou K., Mergia K., Messoloras S., Packer L., Nobs C., Ghani Z., Batistoni P., Pillon M., Loreti S.
Journal: Modern Neutron Detection. Proceedings of a Technical Meeting
https://www-pub.iaea.org/MTCD/Publications/PDF/TE-1935_web.pdf
Abstract: For future fusion plants, such as DEMO, there is a great need for detectors capable of accurately monitoring neutrons under the harsh conditions imposed by the fusion environment. In particular, it is required to utilize detectors that are capable of accurately measuring neutron fluence under high and variable neutron count rates, high gamma background, high temperature, and high and variable magnetic fields encountered during the measurement. A novel neutron activation detector providing a robust approach for accurate neutron fluence measurements under the harsh environment conditions encountered in a fusion plant is developed. The detector comprises a composite low activation matrix compound capsule containing a defined concentration of added metallic elements (targets). The key novelty is provided by the robust matrix which is enabling measurements to be performed under the extreme conditions encountered in a fusion plant, while the capsule itself does not interfere with the gamma spectrum of the active metallic elements. The capsule is fabricated by graphite or Ceramic Matrix Composite (CMC) enabling the detector not to interfere with the strong magnetic fields and to withstand high temperatures encountered in a fusion plant. The neutron fluence and energy spectrum is evaluated by analysis of the gamma lines produced by the activation reactions in the metallic elements. In this work, the progress in the development of the Novel Neutron Detector for Fusion (VERDI) with respect to the selection of the active elements and the matrix material is discussed. Moreover, the results of a test experiment performed at the ENEA Frascati Neutron Generator to demonstrate the feasibility of using a VERDI detector for measuring neutrons in a reference fusion relevant field are also presented.