Analysis of fuel assemblies inclination due to upper core support plate deflection for reactivity evaluation

Yoshimura, Kazuo; Doda, Norihiro; Igawa, Kenichi*; Uwaba, Tomoyuki; Tanaka, Masaaki; Nemoto, Toshiyuki*

Transactions of the 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 8 Pages, 2024/03

To investigate possibility of the insertion of the reactivity by the deflection of the upper core support plate, structural mechanics analyses of the domain consisting of the fuel assemblies and core support plates and evaluation of the reactivity due to the inclination of the fuel assemblies in EBR-II were carried out. As a result, it was indicated that the upper core support plate deflected downward larger at the low flowrate condition than that at the high flowrate condition and positive reactivity was inserted due to the inclination of the fuel assemblies at the low flowrate condition.

The deformation analysis of JOYO core support-plate for the fast reactor safety characteristic research

; ; ; *

PNC TN9410 96-269, 24 Pages, 1996/09

PNC-TN9410-96-269.pdf:0.94MB

As the factor which affects the reactivity coefficient, there is a thing by the change of the flow characteristic of the core internal structure by the mechanical deformation. This displacement of core support-plate in the JOYO reactor vessel was analyzed by using "FINAS" (Finite Element Nonlinear Structural Analysis System). This displacement is a result of the coolant loading difference between the shutdown and full operational primary flow rates. The displacement of core support-plate in the JOYO reactor vessel was analyzed by using "FINAS" (Finite Element Nonlinear Structural Analysis System). This displacement is a result of the coolant loading difference between the shutdown and full operational primary flow rates. At first, the deformation of the core support was required according to the two-dimensional axisymmetric model. These displacements were used as input in the three-dimensional models of excluding the support rib. As a result, the displacement of the upper core support-plate would be about +0.39mm in the center and the maximum would be about +0.43mm in the fifth row. Because of the displacement of the support-plate was suppressed by the support rib. The whole core support structure was displaced in the upward direction. And, core support-plate of the upper and lower was spread largest about 0.03mm in the tenth row by the high-pressure plenum coolant loading.