Şahin, SümerŞahin,S.Acir,A.Şahin,H.M.Department of Mechanical Engineering2024-07-052024-07-05201090932-390210.3139/124.1100972-s2.0-77957726039https://doi.org/10.3139/124.110097https://hdl.handle.net/20.500.14411/3643Criticality and burn up behavior of the Fixed Bed Nuclear Reactor (FBNR) are investigated for the mixed fuel 233UO2/ThO2 as an alternative to low enriched 235UO2 fuel. CERMET fuel with a zirconium matrix and cladding has been used throughout the study. The main results of the study can be summarized as follows: Reactor criticality is already achieved by ∼2% 233UO2 with the mixed 233UO2/ThO2 fuel. At higher 233U fractions, reactor criticality rises rapidly and exceeds keff > 1.5 already by 9% 233UO2. With 100% 233UO 2, start up criticality can reach keff = 2.0975. Time dependent reactor criticality keff and fuel burn up have been investigated for two different mixed fuel 233UO2/ThO 2 compositions, namely: 4 % 233UO2 + 96 % ThO2 for a reactor power of 40 MWel (120 MWth) and 9 % thUO2 + 91 % ThO2 for a reactor power of 70 MWel (210 MWth). Sufficient reactor criticality (keff > 1.06) for continuous operation without fuel change can be sustained during ∼5 and 12 years with 4 % and 9 % 233UO 2 fractions in the mixed fuel, leading to burn ups of ∼36000 and > 105000 MWD/t, respectively. Thorium based fuel produces no prolific uranium. Plutonium production remains negligible. © Carl Hanser Verlag, München.eninfo:eu-repo/semantics/closedAccess[No Keyword Available]ArticleQ4755243247