Reference toughness curve

With the reference toughness curve approach, the RT m index first came into use as the reference nil-ductility temperature which is determined in accordance with the ASME Code, Section III, Subsection NB-2331. The reference toughness Km curve and the Ki curve for static crack initiation later came into use as part of Section XI where the Km curve was called the crack arrest Xia curve. Thus, the RTndt reference temperature index has become the key material parameter in determining the allowable (P-T) limits for plant operation and for evaluating RPV integrity as the result of extreme transients such as PTS. Note that several years ago, the concept of a different, directly measured fracture toughness Master Curve approach was accepted in the ASME Code based on the index parameter RTjq. This development is covered in detail in Chapter 10. 

The indexing temperature for the reference toughness curves is termed the adjusted reference temperature (ART). ART is the irradiated RTndt plus a margin to account for uncertainties and to provide regulatory... 

With the establishment of the Km curve as the lower bound reference toughness for pressure RPV steels, the RT m for all RPV materials was... 

SI method Methodology Reference flaw Safety factor(s) Fracture toughness curve Comments... 

Reference fracture toughness curve and safety factors... 

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