Determination of the Activity Inventory in the Structural Components of the Dalat Nuclear Research Reactor for Its Decommissioning Planning

This report presents the methods and calculated results of activity inventory in structural components Dalat Nuclear Research Reactor (DNRR). These include shielding concrete, reactor tank, its inside irradiated facilities; thermal thermalizing columns; horizontal channels. The MCNP5 code with a three-dimensional neutron transport model was used to calculate flux distribution, energy spectrum at different locations, activation cross sections long-lived radioactive nuclides activated major materials, including heavy reflection graphite, aluminum reactor. were ORIGEN2.1 point depletion neutron-induced materials time points by modeling irradiation history decay. Radioactivity key products such as 41Ca, 60Co, 55Fe, 63Ni, 152Eu modeled, volumes waste mainly ordinary estimated. Experimental specific activities some typical 152Eu, 63Ni samples showed good agreement results. As part national regulation requirements, obtained data have been develop decommissioning plan for operational DNRR, an estimation about 10 years before permanent shutdown.