Fundamental Understanding of Crack Growth in Structural Components of Generation IV Supercritical Light Water Reactors

Abstract

REPORT DOCUMENTATION PAGEForm Approved OMB NO. Public Reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comment regarding this burden estimates or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and This work contributes to the design of safe and economical Generation-IV Super-Critical Water Reactors (SCWRs) by providing a basis for selecting structural materials to ensure the functionality of in-vessel components during the entire service life. During the second year of the project, we completed electrochemical characterization of the oxide film properties and investigation of crack initiation and propagation for candidate structural materials steels under supercritical conditions. We ranked candidate alloys against their susceptibility to environmentally assisted degradation based on the in situ data measured with an SRI-designed controlled distance electrochemistry (CDE) arrangement. A correlation between measurable oxide film properties and susceptibility of austenitic steels to environmentally assisted degradation was observed experimentally. One of the major practical results of the present work is the experimentally proven ability of the economical CDE technique to supply in situ data for ranking candidate structural materials for Generation-IV SCWRs. A potential use of the CDE arrangement developed at SRI for building in situ sensors for monitoring water chemistry in the heat transport circuit of Generation-IV SCWRs was evaluated and proved to be feasible. Understanding basic phenomena. Kinetic parameters of the charge and mass transport processes in the metal/oxide film/supercritical water system are derived from in situ oxide film studies to understand and quantify the rate-controlling processes and, eventually, the fundamentals of the metal oxidation phenomenon at supercritical temperatures. Providing a basis for the development of new alloys. Integration of the in situexperimental information on oxide film resistance to charge and mass transport for alloys of various compositions, along with fracture surface analysis and current theoretical understanding of the relationship between properties of the oxide films and stability of materials, is expected to aid in material selection and the development process. It will do so by providing recommendations for chemical compositions of the alloys in regard to their expected locations in the reactor (or more specifically, in regard to local temperature and oxidizing conditions). 1 WORK PERFORMED AND PRELIMINARY RESULTSDuring this project, SRI completed the electrochemical characterization of the oxide film prop...