The effect of soluble boron and gadolinium distribution on neutronic parameters of small modular reactor assembly

Publication date: Available online 25 January 2020Source: Radiation Physics and ChemistryAuthor(s): S.S. Mustafa, E.A. AminAbstractEarly commercial PWR first cores started up without using burnable absorbers. This results in short first core cycle lengths, positive moderator temperature coefficients and high relative power peaking. Burnable absorbers are introduced to address these first core limitations. In the present work, the first part studies the effect of boron (as burnable poisons) concentration on a number of the small modular reactor assembly neutronic parameters. Among these parameters are the infinite multiplication factor, the depletion of U-235, the production of fissile plutonium isotopes (Pu-239+Pu-241), the total neutron flux, prompt neutron lifetime and effective fraction of delayed neutrons versus burnup. The effect of combination between soluble boron in moderator and gadolinium oxide mixed with uranium oxide is also investigated. For accomplishing this, MCNPX is used for modeling three small modular reactor assemblies. The first one is boron free model of enrichment 5% U-235. The other two assemblies use the same enrichment with soluble boron content 1000 and 2000 ppm respectively. The final conclusions of this part showed that the addition of soluble boron with moderator has a significant effect on the variation of K-inf versus burnup at the beginning and the end of cycle. Furthermore, the addition of soluble boron has an effect on the depletion of U-23...

Source: Radiation Physics and Chemistry - January 26, 2020 Category: Physics Source Type: research