Weibull statistical models of KIc/ KIa fracture toughness databases for pressure vessel steels with an application to pressurized thermal shock assessments of nuclear reactor pressure vessels

Abstract

This paper presents new statistical representations of recently extended fracture toughness K Ic and K Ia databases for pressure vessel steels. These models were developed by the Heavy Section Steel Technology program at Oak Ridge National Laboratory in support of the current effort by the U.S. Nuclear Regulatory Commission to update its regulatory guidance for pressurized-thermal-shock (PTS) transients in nuclear reactor pressure vessels. The Weibull distribution, with two of its parameters calculated by the Method of Moments point-estimation technique, forms the basis for the new statistical models. An application of the new K Ic/ K Ia models, as implemented in the favor probabilistic fracture mechanics computer program, is also presented for three PTS transients.