Impact of the moderation ratio over the performance of different BWR fuel assemblies

Fuel Assembly Reference Information for SNF Radiation Source Term Calculations

“…The BWR fuel assemblies analyzed in the Framatome ANP 32-5045751-00 report do not contain part-length rods. Partial length fuel rods and inner channels are used in current BWR fuel assemblies to achieve a more homogeneous burnup distribution in the fuel [63]. Therefore, the axial burnup profiles of BWR fuel assemblies with partial length fuel rods are expected to be flatter than the axial burnup profiles of fuel assemblies with full length fuel rods.…”

“…Cobalt-60 is produced almost entirely by thermal and epithermal caption reactions in 59 Co [72]. Other production modes, such as 60 Ni(n,p) 60 Co, 63 Cu(n,) 60 Co, and 58 Fe(n,) 59 Fe − → 59 Co, are insignificant based on low cross-section values and/or low parent nuclide concentrations [72,73]. Improved WE fuel assembly designs that use low Co stainless steel have been produced [19]; however, the permissible concentration levels of the Co impurity in hardware materials were not found in open literature.…”

Analysis of Void Reactivity Coefficient for 3D BWR Assembly Model

“…Thereby, BWR core physics is more complex than physics of other reactors, because the coolant enters the core in a single phase and rapidly develops different two-phase flow regimes with very strong axial dependence. It is worth mentioning that reactor core physics has become even more complicated in recent years, because modern/innovative fuel assemblies have new sophisticated features, such as newly designed inner bypass regions and part-length rods, introducing larger uncertainties in relation to axial void distributions and their impact on integral reactor physical parameters [2][3][4].…”

Uncertainty and Sensitivity Analysis of Void Reactivity Feedback for 3D BWR Assembly Model

“…The U-Gd rods have a density of 9.867 g/cm 3 ; meanwhile MOX fuel rods have a density of 9.921 g/cm 3 . The fuel temperature was set at 627 ∘ C. The density of the Zircaloy cladding and water channel was 6.55 g/cm 3 .…”

“…In addition, a void fraction profile may change during a fuel assembly lifetime in reactor core due to other factors, such as fuel burnup, control blade position, type of neighbouring fuel assemblies, and assembly position within the core. It is worth mentioning that reactor core physics has become even more complicated in recent years, because modern fuel assemblies have new sophisticated features, such as newly designed inner bypass regions and part length rods, introducing larger uncertainties in relation to axial void distributions and their impact on integral reactor physical parameters [1][2][3].…”