The method of assessing Q2 and Q3 break preclusion pipe stress

Break preclusion is a deterministic concept which ensures that a break in a pipe can be ruled out by preventive measures (requirements on design, materials, product forms, manufacturing, quality assurance, analysis of fatigue crack growth) and surveillance measures (requirements on transient and water chemistry monitoring, leakage detection, in-service inspection). Break Preclusion implies that piping integrity will be maintained throughout the lifetime of the plant. Surface disfigurement lead to Leakage which results from a localized total loss of wall thickness in a pressurized component, either due to a stable (sub-critical) wall crack, or a degradation mechanism, such as the loss of wall thickness due to erosion-corrosion. A leak results in the loss of containment capability for the pressurized component without occurrence of a break which means the loss of integrity of a pipe (circumferential rupture) as a result of an unstable circumferential crack in this component. When designing safety classified structures and mechanical, electrical and I and C components to withstand forces from postulated pipe leaks and breaks, the following effects are considered. The paper described it is necessary to analysis and validate the break preclusion pipe for that Q2 and Q3 are rationality and security in design process by the criterion. It has realized that high quality design, efficient manufacture and operation monitor prevent loss of containment. It was brought depth recovery into effect that the qualification of reducing break is consistent with the purpose that the pipe has a full containment during the unit life period. (authors)