Measuring the delayed neutrons multiplicity and kinetic parameters for the thermal induced fission of ²³⁵U, ²³⁹Pu and ²³³U

In the normal operation of nuclear reactors, kinetic behavior neutron population in core is driven by so-called delayed neutrons (DN). The DN yield per fission, their average lifetime and groups’ abundances are main physical parameters used to predict reactor its reactivity. overall uncertainty associated reactivity predictions, which linked directly safety margins, thus closely dependent on a few with DN. Depending data library, present significant discrepancies, even for major fissile isotopes such as 235 U or 239 Pu. this context, CEA has long been working improving data. 2018, launched ALDEN project (Average Lifetime DElayed Neutrons) framework collaboration between CEA/DES, CEA/DRF, CNRS/IN2P3 (LPSC, CENBG, LPC), ENSICAEN Caen University. This program aims at measuring kinetics derive yield, abundances. Two experimental campaigns focusing thermal fission were conducted 2018 2019. They demonstrated concept feasibility gave high quality estimations multiplicity (1.631 ± 0.014 %) (8.82 0.6 s) U. More recently March 2021, more ambitious irradiation campaign was Pu 233 paper details new setup, upgraded meet ILL requirements handling plutonium. analysis process presented, focus problem dead time correction. Finally, some preliminary decay curves showed discussed.