Commissioning of the New Irradiation Device for Neutron Transmutation Doping

Abstract

The LVR-15 reactor is a 10 MW tank type multi-purpose research reactor. The reactor is utilized for production of a wide scale of isotopes with the main focus on generators, testing of materials and chemical regimes of coolant in irradiation rigs and experimental loops (in-pile and out of pile), beam experiments and neutron transmutation doping. The current capacity for neutron transmutation doping was one irradiation facility dedicated to maximum 3 inch ingots. Recently, this capacity was increased by a new irradiation device. Although, the current market demand for neutron transmutation doping is for ingots with diameters up to 6 inch, occasionally even 10 inch, the new device was designed for smaller ingots. The main reason for having a 4 inch diameter maximum for this new device was the limited space in the reactor core. For commissioning purposes of the irradiation channel and for repetitive verification of irradiation parameters special dummy ingots were developed. These dummies can be equipped with three sets of activation detectors, so that the neutron fluence across the ingot can be determined. Within the commissioning, two sets of measurements using the dummy ingots were performed. The primary purpose of these measurements was to verify axial positioning of the irradiation device. The first measurement revealed some issues with accurate positioning of the irradiation device. After these issues were fixed, a new set of measurements using dummy ingots was performed. As a result of these measurements, an estimation of optimal irradiation position was refined. For this refined position a set of silicon ingots was irradiated. From the irradiation results of these ingots, a calibration of the online monitoring system could be done. The successful irradiation of this set of silicon ingots was the last test of the device commissioning; the positioning of the irradiation device and its performance was verified.