Fission gas monitoring for the AGR-5/6/7 experiment

•A fueled multiple-capsule experiment.•AGR-5/6/7 is the fourth and last experiment in the “AGR-experiment” series.•Data on fission product migration and retention in the next generation reactor.•Using short-lived gaseous fission product data for to determine transport volumes. The AGR-5/6/7 test is a fueled multiple-capsule experiment currently being irra- diated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL). AGR-5/6/7 is the fourth and last experiment in the “AGR-experiment” series which is being performed and funded by the United States Department of Energy (DOE) as part of the INL Advanced Reactor Technologies (ART) program. To derive isotopic release-to-birth ratio’s, the fission gas measured at the Fission Product Monitoring System (FPMS) must be corrected for decay during the transport from the constantly-irradiated fuel capsule to the FPMS measurement location. The decay time is dependent on the capsule effluent flow rate and transport volume. Capsule effluent flow rates are measured and recorded into the ATR Distributed Control System (DCS). Therefore, only the capsule specific transport volumes are needed for accurate transport decay corrections. This paper contains a summary of the AGR-5/6/7 experiment test train, details of the leadout flow experiment, the process of obtaining the short lived gaseous fission product data for use in determining the transport volumes and the AGR-5/6/7 transport volumes that will be used to calculate the capsule specific isotopic release activities and preliminary release-to-birth ratio’s for the AGR-5/6/7 experiment.