From Charpy to Present Impact Testing D. Franqois and A. Pineau (Eds.) 92002 Elsevier Science Ltd. and ESIS. All rights reserved 307 CORRELATING CHARPY AND J-FRACTURE TOUGHNESS PARAMETERS IN STRUCTURAL INTEGRITY ASSESSMENTS J.R. Tarpani i and D. Spinelli i t Engineering School of S~lo Carlos, SMM-EESC-USP 13566-590, Brazil,jrpan@,sc, usp.br ABSTRACT The Paris & Johnson's J~o criterion against ductile instability and the here proposed J-value for a 5 mm ductile crack growth (Jsm) have been correlated to the Charpy impact energy of pre-cracked side- grooved testpieces, for a wide range of fracture toughness of a nuclear grade steel. The correlation has been performed in terms of lower bounds, which have been applied to the structural integrity assessment of internally pressurized flawed vessels. The results have shown that both the Jso and J5mm criteria can be applied, through the Charpy impact testing, for periodic inspections and hydrotest evaluations of this class of structural components. KEY WORDS Charpy-fracture toughness correlation, J-R curve, RPV steel, Structural integrity, Tearing instability INTRODUCTION The J-integral is regularly applied in structural integrity assessment of nuclear fuel containment vessels, aiming to ensure safe operational conditions against fracture by ductile cracking mechanisms [1,2]. The most widely used J-criteria are the crack initiation value, Ji [3], and the Paris ~ Johnson's Js0 against ductile tearing instability [4]. Inasmuch as J-integral testing of irradiated materials is complex, costly, hazardous and time consuming, there has been a natural interest in establishing trusty correlation between elastoplastic J-integral criteria and those derived from simpler, cheaper, safer and faster test methodologies, as the Charpy impact testing [5,6]. In this work, Js0-values resulting from miniaturized compact tensile testpieces, C[T], were tentatively correlated to Charpy impact energies of pre-cracked side-grooved testpieces machined from a nuclear grade steel presenting a broad range of fracture resistance. The same was performed for the here-proposed Jsmmcriterion, i.e., J-value for a 5 mm ductile crack extension. Lower bound correlation results were then applied to the analytical structural integrity assessment of prototype and full-scale PWR vessels. MATERIAL AND TESTPIECES Miniaturized J-compact tensile specimens [7,8] were machined with a variety of plastic constraints from a thick forged plate (T/4 position, T-L orientation) of a nuclear grade steel (A508-3A, chemistry in rable 1), in the as-received and several thermally embrittled conditions. They were fatigue pre-