STRATEGIES FOR INSERVICE INSPECTION OF COMPACT HEAT EXCHANGERS IN HIGH TEMPERATURE REACTORS

Abstract

The U.S. Department of Energy is sponsoring research to support the development of the compact heat exchanger (CHX) for use in high temperature advanced reactors. The project is being executed by an Integrated Research Project (IRP) and includes team members from the University of Wisconsin– Madison, University of Michigan, Georgia Institute of Technology, University of Idaho, North Carolina State University, Oregon State University, Electric Power Research Institute, MPR Associates, and heat exchanger manufacturers CompRex and Vacuum Process Engineering (References 1& 2). The objective of the research is to enable the use of compact heat exchanger designs in high temperature advanced reactor service in order to improve plant efficiency and economics. A necessary step for achieving this objective is to ensure that the ASME Boiler and Pressure Vessel Code, Section III (Reference 3) has rules for the construction of CHXs for nuclear service. However, construction rules alone are not sufficient to deploy a compact heat exchanger in an advanced reactor. ASME Section XI (Reference 4) Rules for the Inservice Inspection (ISI) of a heat exchanger in an operating nuclear reactor will be required as well. The failure mechanisms for compact heat exchanger are unique and are not well understood since they have limited operating experience. The IRP will develop an inservice inspection roadmap to guide IRP research that will enable an owner/operator of an advanced nuclear reactor to implement an appropriate inservice inspection program for a compact heat exchanger. Failure mechanisms and their associated probabilities are the key inputs to a successful inspection program. The inspection roadmap will make use of the soon to be published ASME Section XI, Division 2, Reliability and Integrity Management (RIM) methodology. RIM is a non-deterministic, technology neutral, approach to inservice inspection. A RIM based ISI program is developed by an owner considering the entire reactor technology safety case rather than on the specific component technology. Therefore, owners will need specific information regarding the performance, failure modes, reliability, and inspection options for compact heat exchangers in order to incorporate such a heat exchanger into the plant design. This paper outlines the IRP research as it relates to inputs needed by an owner for the eventual development of an ISI program that includes compact heat exchangers.