In-Core Neutron Measurement using SiC Detector for Fast Response

A SiC PIN diode detector (4H-SiC with 30 μm thick epitaxial I-layer) was developed and evaluated its performance under the harsh environment of the High Flux Advanced Neutron Application Reactor (HANARO) reactor core at Korea Atomic Energy Research Institute (KAERI). The detector was designed to be tolerable against thermal and radiation damages, by adopting Ti/Au electrode structure and crimped connection between the sensor and signal wire. Fabricated SiC detector was inserted into the HANARO irradiation hole (IP-4) to test core neutron detection performance at in-core environment. The radiation induced signal was obtained as reactor power increased up to 10 MWth. Maximum thermal and fast neutron fluxes were 9.4×10
¹²
and 2.5×10
⁹
n/cm
²
/s, respectively, and total neutron fluence irradiated on the detector was 4.7×10
¹⁶
n/cm
²
. Reverse bias of 60 V was applied to ensure maximum detector performance. The detector showed good linearity of response up to the tested fluence, with R
²
= 0.9997. The SiC detector's response speed was evaluated by comparison to that of a Rh self-powered neutron detector (SPND). The delay times of SiC detector signal and Rh SPND signal were determined by evaluating when the current increased to 90% of saturation current at each power step. Averaged SiC detector delay time = 12.8 s, approximately 11 times shorter that of the Rh SPND (140 s).