Nuclide inventory of FIR 1 TRIGA research reactor fuel

FiR 1, a TRIGA Mark II type research reactor, was operated in Finland for years 1962–2015 and will be decommissioned during the following few years. Data on the fuel nuclide inventories is needed to estimate fuel rod activities and dose rates for safe fuel removal, transportation and final disposal. This paper presents comparison calculations for FiR 1 reactor fuel nuclide activity inventory performed with VTT’s Monte Carlo based continuous energy reactor physics code Serpent 2 with internal burnup and depletion calculation routine, and with the point-depletion code ORIGEN-S using MCNP5 pre-calculated three-group neutron fluxes as spectrum weight factors. Results are presented at the time of final reactor shutdown and after a cooling period of nine months, which corresponds to the systematic dose rate measurements for all the fuel rods performed in 2016...