µRANIA-V: an innovative solution for neutron detection in homeland security

Detection of neutrons is becoming of the utmost importance, especially in the studies of radioactive waste and in homeland security applications. The crisis of 3He availability has required the development of innovative techniques. One solution is to develop light gas detectors for neutron counting to be used as portals for ports and airports. The neutron is converted on the Boron-coated cathode, releasing a charged particle, whose passage can be identified by the gas detector. While several technologies have been deployed in the past, the project μRANIA-V (μRwell Advanced Neutron Identification Apparatus) aims to detect thermal neutrons by means of the μRwell technology, an innovative gas detector. The goal is to produce tiles to operate as portals in homeland security or for radioactive waste management. The technological transfer towards the industry has started, thus the production can be cost-effective also owing to a construction process relatively easier compared to similar apparatus. By reading directly the signals from the amplification stage, the neutrons can be counted with simplified electronics further reducing the total cost. In this paper, the project will be described, with details on the μRwell technology and on the neutron counting, on the test beam performed, and on the future plans.

Developing and testing a miniature fiber-coupled scintillator for in-core neutron counting in CROCUS

An advanced neutron detection system for highly localized measurements in nuclear reactor cores was developed and tested in the Laboratory for Reactor Physics and System Behaviour (LRS) at the École polytechnique fédérale de Lausanne (EPFL), Switzerland, in close collaboration with the Detector group of the Laboratory for Particle Physics (LTP) at the Paul Scherrer Institute (PSI), Switzerland. The miniature-size detector is based on the coupling of a ZnS:6LiF scintillator/converter screen of 1 mm2 and 0.2 mm thickness with a 10-m optical fiber, the latter being connected to a silicon photomultiplier (SiPM). In this development version, the output signal is processed via analog read-out electronics. The present work documents the characterization of a detection system prototype in the mixedradiation fields o f t he C ARROUSEL f acility a nd i ts t esting in the CROCUS zero-power reactor operated at LRS. The fibercoupled scintillator shows a linear response with the reactor power increase up to 6.5 W (i.e. around 108 cm-2s-1 total neutron flux), with a s ubsequent l oss o f l inearity d ue t o e lectronic dead time of the analog system. Nevertheless, the detector shows excellent neutron counting capabilities whether compared to other localized detection systems available at LRS, e.g. miniature fission chambers and an sCVD diamond detector.