In-Pile Qualification of the Fast-Neutron-Detection-System

Damien Fourmentel, Jean-François Villard, Christophe Destouches, Benoit Geslot, Ludo Vermeeren, Marc Schyns

    Research outputpeer-review


    In order to improve measurement techniques for neutron flux assessment, a unique system for online measurement of fast neutron flux has been developed and recently qualified in-pile by the French Alternative Energies and Atomic Energy Commission (CEA) in cooperation with the Belgian Nuclear Research Centre (SCK•ECEN). The Fast-Neutron-Detection-System (FNDS) has been designed to monitor accurately high-energy neutrons flux (E > 1 MeV) in typical Material Testing Reactor conditions, where overall neutron flux level can be as high as 1015 and is generally dominated by thermal neutrons. Moreover, the neutron flux is coupled with a high gamma flux of typically a few 1015 γ.cm-2.s-1, which can be highly disturbing for the online measurement of neutron fluxes. The patented FNDS system is based on two detectors, including a miniature fission chamber with a special fissile material presenting an energy threshold near 1 MeV, which can be 242Pu for MTR conditions. Fission chambers are operated in Campbelling mode for an efficient gamma rejection. FNDS also includes a specific software that processes measurements to compensate online the fissile material depletion and to adjust the sensitivity of the detectors, in order to produce a precise evaluation of both thermal and fast neutron flux even after long term irradiation. FNDS has been validated through a two-step experimental program. A first set of tests was performed at BR2 reactor operated by SCK•CEN in Belgium. Then a second test was recently completed at ISIS reactor operated by CEA in France. FNDS proved its ability to measure online the fast neutron flux with an overall accuracy better than 5%.
    Original languageEnglish
    Title of host publicationEPJ Web of Conferences
    Subtitle of host publication5th International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications - ANIMMA 2017
    Number of pages3
    StatePublished - 10 Jan 2018
    Event2017 - ANIMMA - Advancements in Nuclear Instrumentation Measurement Methods and their Applications: International Conference on Advancements in Nuclear Instrumentation, Measurement Methods and their Applications - Palais des Congrès, Liège
    Duration: 19 Jun 201723 Jun 2017

    Publication series

    NameEPJ Web of Conferences
    PublisherEDP Sciences
    ISSN (Print)2100-014X


    Conference2017 - ANIMMA - Advancements in Nuclear Instrumentation Measurement Methods and their Applications
    Internet address

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