Use of neutron coincidence counters for the estimation of fissile content in irradiated material

Research outputpeer-review


Neutron coincidence counters based on 3He proportional counters have been widely used for the detection of fissile material in applications such as nuclear safeguards, security, and decommissioning. Recently, SCK•CEN purchased two used Canberra WM3400 neutron coincidence counters in the frame of the initial characterization process for the decommissioning of historical sodium loops. Several so-called In-Pile Sections (IPS) were irradiated in the BR2 reactor at SCK•CEN during 1970-1980’s to study the rupture of fast reactor fuel in accidental conditions. The section of the IPS containing the original fuel pins was already removed from the SCK•CEN site for further R&D activities, but the residual fissile material in the remaining part, containing the loop components, needs to be quantified in order to determine the strategy for segmentation, conditioning and transportation. This contribution focuses on the initial testing of the detectors to verify their correct operation. A Monte Carlo model of the detector was developed with the MCNPX-PoliMi code, and a comparison between experiments and simulation results have been conducted. Measurements with a 252Cf source were carried out and the point model equations were applied to calculate the detector efficiency and die-away time. The initial testing confirmed the operating conditions recommended by the manufacturer, although the Totals and Reals rates estimated with Monte Carlo simulations were approximately 6% and 18% larger than the measured values. In addition, a strong sensitivity to gamma-rays was observed in a series of experiments.
Original languageEnglish
Title of host publicationInternational Workshop on Numerical Modelling of NDA Instrumentation and Methods for Nuclear Safeguards
PublisherEuropean Safeguard Research and Development Association
Number of pages12
StatePublished - 16 May 2018
Event2018 - NDA: International Workshop on Numerical Modelling of NDA Instrumentation and Methods for Nuclear Safeguards - LUX Congress, Luxembourg
Duration: 16 May 201817 May 2018


Conference2018 - NDA
Abbreviated titleNM-NDA-IMNS18
Internet address

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