IMPROVED TECHNIQUES FOR OBTAINING FRACTURE RESISTANCE CURVES FROM SUB-SIZE SPECIMENS-

THIS PROGRAM WILL DEVELOP METHODS TO OVERCOME THE LIMITATIONS OF CLASSICAL ELASTIC-PLASTIC FRACTURE MECHANICS ON SPECIMEN SIZE WHEN DEVELOPING RESISTANCE CURVES. THE OBJECTIVE OF THE PROJECT IS ASSESSING THE INTEGRITY OF REACTOR PRESSURE VESSELS (RPVS) BY MAKING MAXIMUM MEANINGFUL USE OF THE INFORMATION OBTAINED FROM SMALL SPECIMENS, WHICH ARE OFTEN THE ONLY AVAILABLE SOURCE, WITHOUT AN UNNECESSARY REDUCTION IN THE PRE- DICTED MATERIAL TOUGHNESS OR TEARING RESISTANCE. IN PHASE I, THE QUESTION OF WHETHER OR NOT A CORRECT SUBSIZE DESIGN EXISTS WILL BE ADDRESSED, AND PARAMETERS FOR SUBSIZE SPECIMEN DESIGN WILL BE PRESCRIBED AS A FUNCTION OF SPECIMEN DIMENSIONS, FLOW STRESS, AND OTHER FACTORS. ALSO, EXTRAPOLATION TECHNIQUES FOR EXTENDING THE DATA TO LARGER VALUES OF J AND A A, WILL BE DEVISED. PHASE II OF THE PROJECT WOULD INVOLVE THE ACTUAL DESIGN, TESTING, AND VERIFICATION OF AN IMPROVED SUBSIZE SPECI- MEN FOR USE IN RPV SURVEILLANCE, ALONG WITH APPROPRIATE DATA ANALYSIS METHODS.