Abstract
A calibration technology of the self-powered neutron detectors (SPNDs) using a large vertical irradiation hole of HANARO is developed. The 40 Rh-SPNDs are installed on the polycarbonate plastic support, and the gold wires with the same length as the effective length of the rhodium emitter of the SPND are also installed to measure the neutron flux on the SPND. They are irradiated at a low reactor power, and the SPND current is measured using the pico-ammeter. The external gamma-rays which affect the SPND current response are analyzed using the Monte Carlo simulation for various irradiation conditions in HANARO. It is confirmed that the effect of the external gamma-rays to the SPND current is dependent on the reactor characteristics, and that it is affected by materials around the detector. The current signals due to the external gamma-rays can be either positive or negative, in that the net flow of the current may be either in the same or the opposite direction as the neutron-induced current by the rhodium emitter. From the above procedure, the effective calibration methodology of multiple SPNDs using the large hole of HANARO is developed. It could be useful for the calibration experiment of the neutron detectors in the research reactors.
Highlights
SELF-Powered Neutron Detectors (SPNDs) have been widely used for monitoring the neutron flux in reactors as well as in irradiation facilities
Because the self-powered neutron detector (SPND) doesn’t need to use the external bias supply applied to the detector, it is used for a typical neutron detector in the nuclear power plants and for real-time neuron flux monitoring in the research reactors [2]
We described a method for calibrating sensitivity of multiple SPNDs installed at a large vertical hole of HANARO
Summary
SELF-Powered Neutron Detectors (SPNDs) have been widely used for monitoring the neutron flux in reactors as well as in irradiation facilities. Because the SPND doesn’t need to use the external bias supply applied to the detector, it is used for a typical neutron detector in the nuclear power plants and for real-time neuron flux monitoring in the research reactors [2]. For the neutron flux monitoring using the SPND, sensitivity that is an intrinsic characteristic of the detector is required. HANARO, a 30 MW research reactor in KAERI, is a good tool for a determination of the sensitivity of the SPND. In order to estimate the sensitivity of the SPND precisely, the reactor should be operated at low-power, and in this situation, influence of the external γ-rays is not insignificant.
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