Passive Autocatalytic Recombiners Periodic Testing Issue

During the refueling outage (RFO) 2013 at NPP Krško, electric hydrogen recombiners, a system for control during severe accidents and design basis accidents, were replaced by passive autocatalytic recombiners (PARs). next RFOs in 2015, 2016 2018, periodic tests of PAR cartridges performed. The testing NIS-PARs shall prove that catalytic reaction starts up as specified. According to licenced procedure, each six obtained tested NIS test device (TD). Randomly selected did not pass room temperature (RT). Cartridges do have be regenerated according NEK followed again TD demonstrate success regeneration. effort full regeneration all is necessary conservative. Due significant unexpected workload outages, need enhanced procedure with higher catalyst priority. concept this based on conclusion PARs installed Krško functional under accident conditions operational cycles (OL27, OL28 OL29) even though RT (testing but well below temperatures was successful). Revision methodology direction requires development new TD. New will allow cartridge measurements defined elevated (range 40 - 70 deg C). It vacuum oven type or upgraded current device. In both examples it provide least two same time, independently, however whole tested. Test gas remains 3 vol. % air. For detailed plant specific investigation material behavior, increased developed. Additionally, different batch behavior