Comparison of various hours living fission products for absolute power density determination in VVER-1000 mock up in LR-0 reactor

Abstract Measuring power level of zero power reactor is a quite difficult task. Due to the absence of measurable cooling media heating, it is necessary to employ a different method. The gamma-ray spectroscopy of fission products induced within reactor operation is one of possible ways of power determination. The method is based on the proportionality between fission product buildup and released power. The 92 Sr fission product was previously preferred as nuclide for LR-0 power determination for short-time irradiation experiments. This work aims to find more appropriate candidates, because the 92 Sr, however suitable, has a short half-life, which limits the maximal measurable amount of fuel pins within a single irradiation batch. The comparison of various isotopes is realized for 92 Sr, 97 Zr, 135 I, 91 Sr, and 88 Kr. The comparison between calculated and experimentally determined (C/E-1 values) net peak areas is assessed for these fission products. Experimental results show that studied fission products, except 88 Kr, are in comparable agreement with 92 Sr results. Since 91 Sr has notably higher half-life than 92 Sr, 91 Sr seems to be more appropriate marker in experiments with a large number of measured fuel pins.