Study on failure evaluation of reactor pressure vessel lower head due to sever accidents, 2-1; Evaluation of material deformation under multiaxial stress condition

Nemoto, Yoshiyuki  ; Kato, Hitoshi; Kaji, Yoshiyuki  ; Nagase, Fumihisa 

Using finite element method (FEM) analysis, JAEA studies on failure of reactor pressure vessel lower head due to the sever accidents in Fukushima. Multi-axial stress condition should be taken account in evaluation of material deformation in complicated structure, e.g., joint parts of lower head and control rod guide tube, however material property data obtained by former uniaxial material testing is applied in the FEM analysis. In this study, internal pressure creep test and its FEM modeling analysis were conducted to evaluate applicability of uniaxial data for analysis of creep behavior under multi-axial stress condition.