1. A mm3 Fiber-Coupled Scintillator for In-Core Thermal Neutron Detection in CROCUS.
- Author
-
Vitullo, Fanny, Lamirand, Vincent, Mosset, Jean-Baptiste, Frajtag, Pavel, Pakari, Oskari, Perret, Gregory, and Pautz, Andreas
- Subjects
- *
MONTE Carlo method , *THERMAL neutrons , *NEUTRON counters , *NEUTRON flux , *OPTICAL fibers , *CONTROL elements (Nuclear reactors) , *FISSION counters , *SCINTILLATORS , *DETECTORS - Abstract
This article presents the development, full-characterization, and in-core testing of a miniature neutron detector for the investigation of highly localized in-core neutronics effects in the zero-power reactor CROCUS, operated at the École Polytechnique fédérale de Lausanne (EPFL), Switzerland. A ZnS: 6LiF screen, mixing inorganic scintillator and neutron converter, with a surface of 1 mm2 and a thickness of 0.2 mm, was coupled with a silicon photomultiplier (SiPM) via a 10-m optical fiber. Analog readout electronics were adopted in this prototype version to process the SiPM output signal. A first campaign was carried out to assess the detection system capabilities in terms of neutron detection and counting in mixed neutron-gamma radiation fields. The miniature detector was thoroughly characterized with a Pu-Be source installed in the CARROUSEL facility and was subsequently tested inside a control rod guide tube of the CROCUS reactor in different reactor conditions, i.e., at shutdown, startup, and critical. The detector shows a linear response with a reactor power increase up to 6.5 W (i.e., around 108 cm−2 ⋅ s−1 total neutron flux) and excellent neutron counting capabilities, when compared to other localized detection systems available in CROCUS, such as the miniature fission chambers and single-crystal vapor deposited (sCVD) diamond detectors. In addition, the exposure of the miniature detector to a 60Co source with an activity of ~250 GBq, combined with the computation of the gamma flux in CROCUS with the Serpent 2 Monte Carlo code, confirmed the gamma insensitivity of the system in a mixed neutron-gamma field. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF