Neutron measurements at the TRIGA reactor Ljubljana for core inventory verification

Safeguards inspections are periodically made in nuclear facilities as a consequence to the Nonproliferation Treaty. The inspection methods are permanently being improved and should not cause serious interference with the reactor operation. Therefore, Core Inventory Verifier (CIVR) is being developed as an indirect quantitative method for verification of the core inventory and detection of the declared operation of research reactors. The CIVR method measures the kinetic behavior of the reactor as well as the neutron flux and its energy distribution at several points inside or outside the core. Measured data taken during inspection is compared with the set of reference data determined previously. The inspection result ''nothing has changed'' indicates that all declared nuclear material really exists in the core. TRIGA reactors are one of the target groups for the CIVR method. The TRIGA reactor Ljubljana was chosen as a reference facility. First results of test series at the TRIGA reactor Ljubljana will be presented in this paper.(author)