Self-Powered Detectors for ITER Test Blanket Modules

Various types of nuclear detection instruments will be installed in the Test Blanket Modules (TBM) of ITER, the fusion reactor under construction at St. Paul lez Durance in France. In this work, experimental tests and computational modelling are undertaken to check the possibility of using Self Powered Detectors (SPD) for the measurement of Neutron and/or Gamma flux in European ITER TBMs. Such detectors are commonly used in fission reactors for neutron monitoring due to their compactness and high-reliability. Commercial Self Powered Neutron detectors (SPND) are tailored to the application in thermal fission reactors and are thus, sensitive to low energy neutrons. New materials are selected for the TBM application to replace the central emitter and make it responsive to fast neutrons up to the energy of D-T neutrons. A test detector with a flexible design was prepared in-house and used for experiments with 14-MeV neutrons at the Technical University of Dresden. Multiple factors like different sources of noise, parasitic reactions of high energy neutrons and gammas etc. were found to affect the small current (10-13 to 10-11 Ampere) output of the considered beryllium-emitter based SPND. ... mehrAn alternative measurement method using plastic scintillator based counting was utilized to compare the electron emission rates from different material foils, which can be used to make emitter-collector combinations. Furthermore, a multi-step Monte Carlo particle transport method for the estimation of the sensitivity of these detectors to the relevant neutron and gamma spectra is used to check the appropriate combinations of materials and their size