| The reactor pressure vessel(RPV)is a vital part of a reactor and works under high temperature,high pressure and neutron radiation during the almost whole life span.It is significant to study the structural integrity of a RPV under pressurized thermal shock(PTS)which may cause great damage to RPV.As RPV is casted and huge,it is strict and will cost much material and fund in producing technology.Because fracture exists in each RPV without exception,it is crucial to study whether the RPV can maintain normal function with fracture under possible conditions.Recently,constraint effect is usually used in fracture researches.As a result,K-T method,J-Q method and J-A2 method have been proposed for fracture researches and are used frequently.Also a number of standards and engineering methods have been published by different organizations and institutions for structural integrity assessment and economic benefit.This paper is to use J-A2 two parameters method to analyze the fracture behavior of RPV.A series of finite element models based on fact will be used in fracture and constraint analyses.Following is the main work:(1)Clad effect to RPV in different conditions are studied.Clad effect can be ignored in normal condition.It will cause higher J in small loss of coolant accident if clad is considered.However,considering clad effect result in lower J in medium loss of coolant accident.(2)Various axial load in wall have been considered to analyze the distinction between single axial load and biaxial load.Only A2 value near the surface point of the crack increasing with the axial load.(3)R6 method are used in structural integrity assessment for RPV in normal condition.Constraint effect is also considered when assessing and causes a safer assess result.(4)When assessing the structural integrity of RPV in medium loss of coolant accident,master curve method is applied.More safety margin is presented in the result when constraint effect is considered. |
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