Neutron and Gamma Spectrometry in the Research Reactor LR-0

The complex measurement system for the full-scale VVER models (mock-ups), created in the research reactor LR-0, is discussed. Fast neutron (energy from 0.5 to 10 MeV) and gamma spectra are measured in several representative points of the mock-ups by the two-parameter spectrometer with the cylindrical stilbene scintillation detectors. Measurements in the thermal and epithermal neutron region are carried out with the activation method using a broad set of activation monitors and with the 3 He(n,p) counter. Activation measurements with threshold fast neutron detectors enlarge also the proton-recoil spectra measurements, such activation measurements are carried out especially in cases, when a spectrometer cannot be put in the necessary position. The core fission rate distribution is obtained by means of gamma-scanning of the fuel pins. The low noise precise power (flux density) monitoring system, independent of the operation control system, was developed in the LR-0 reactor for mock-up experiments.