New Neutron Imaging Facility NIFFLER at Very Low Power Reactor VR-1.

The paper describes the construction of the neutron imaging facility at the very low-power research reactor VR-1. The training reactor VR-1 is operated by the Czech Technical University in Prague, Czech Republic. It is mainly used for the education of students in the field of nuclear engineering as well as for the training of professionals. Neutron imaging is the new field of VR-1 reactor utilisation currently under development. Extremely low reactor power at the level of 100 W brought many challenges that were necessary to overcome to build and commission a sustainable neutron radiography facility. The paper describes the reactor's neutron flux verification and the basic concept and design of the neutron imaging instrumentation. The first experimental results were mainly dedicated to testing the detection system for different radial beam port configurations, different L/D ratios, and different exposure times. Preliminary results of neutron radiography and tomography measurements at VR-1 clearly showed the potential of using neutron imaging in low-power reactors such as the VR-1 reactor.

Investigation of mammoth remains using the neutron activation analysis at the Training Reactor VR-1.

At the time when the importance of the interdisciplinary research increases, the nuclear analytical techniques supported by the small research reactors represent a useful tool for investigation of human society, culture, history etc. The historical, archaeological, and palaeontological samples and objects of cultural heritage can be easily studied using the radioanalytical methods such as the neutron activation analysis. This paper deals with the detailed investigation of fragments of mammoth remains from the Mid-Upper Palaeolithic site Pavlov VI by means of the instrumental neutron activation analysis at the Training Reactor VR-1 of the Czech Technical University in Prague. Six mammoth hard tissue samples (fragments of bones, tusk, and molar) from the Institute of Archaeology of the Czech Academy of Sciences were irradiated in the dry vertical irradiation channel with thermal neutron field (φ=2×109cm-2s-1) at maximum reactor power (80 W). The activated mammoth samples were analysed employing the nuclear γ-spectrometry and semiconductor HPGe detector, and the composition of the remains was determined (qualitative and quantitative analysis). The presence of Na, Cl, K, As, Fe, Sr, Mn, Br, I, Ba, and U was revealed in studied mammoth samples. Based on obtained production rates, the concentrations of Fe, Sr, Na, K, As, and U were determined. The results presented in this paper show clearly that the low-power Training Reactor VR-1 is excellent tool for the neutron activation analysis experiments within the interdisciplinary research and can provide experimental data important for archaeologists and palaeontologists.