KüFA safety testing of HTR fuel pebbles irradiated in the High Flux Reactor in Petten

This paper discusses and compares the releases obtained from KüFA-testing the pebbles HFR-K5/3 and HFR-EU1/3, which were both irradiated in the High Flux Reactor (HFR) in Petten. We present the time-dependent fractional release of the volatile fission product 137Cs as well as the fission gas 85Kr for both pebbles. For HFR-EU1/3 the isotopes 134Cs and 154Eu as well as the shorter-lived 110mAg have also been measured. A detailed description of the experimental setup and its accuracy is given. The data for the recently tested pebbles is discussed in the context of previous results.