دراسة أثر التعديلات التصميمية في بنية حزمة الوقود على خصائص التدفق النتروني لقلب المفاعل VVER-1000

Abstract EN

In this work the designed and manufacturing development of TVSA+ fuel assemblies and their effect on the VVER-1OOO operating parameters were calculated and compared with TVS assemblies, the results show that the replacement of the Steel as construction elements of FA strength skeleton by zirconium alloy, can improve the neutron balance in the fuel lattice and decrease the fuel enrichment needed to attach the criticality level and reactivity demands, (saving its multiplying properties) and, thus, reduce the cost of fuel.

the other result shows that by compensation a part of excess reactivity using the Gd2O3 "as integrated burnable absorbers mixed with fuel" allowed to increase fuel enrichment which in turn help to increase the reactor period and to decrease boron acid concentration in the moderator which enhanced moderator temperature coefficient The specially designed structure of TVSA+ assembly, so-called stiffness angle, in each of the 6 corners of the fuel assembly was modeled and there accesses of neutron flux were evaluated, the result show that the present of these stiffness angles help to improve the neutron balance in the void between assemblies The main core neutronics parameters have been calculated and presented using VVERHGMLC simulator for all suggested cases which showed that TVSA+ assembly can burn in the reactor core with higher safety margins, and doesn't excess any operating limit during the whole reactor cycle.

Furthermore the TVSA+ might allow to achieve long fuel cycle batch, a nearly flat neutron flux, and a high fuel burn up.

KEY WORD: VVER-1000 nuclear reactor, TVSA+ assembly, Advanced fuel cycle, Gd2O3 integrated burnable absorbers