SBIR-STTR Award

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 predicted 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 anda a, will be devised. Phase 11 of the project would involve the actual design, testing, and verification of an improved subsize specimen for use in RPV surveillance, along with appropriate data analysis methods.Anticipated Results/Potential Commercial Applications as described by the awardee:The objective is to be able to obtain fracture mechanics material property data that accurately characterize the toughness or tearing resistance of reactor pressure vessel materials. This will be done by overcoming the limitations of existing subsize fracture mechanics test specimens, by developing alternate specimen designs, by devising schemes for extrapolation of data to larger values of J and A, and by expanding the limits imposed on current specimen designs.

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.