This document represents an update to the original version of this report on the subject code and standards for high temperature gas reactor applications. In particular this report addresses the comments provided by INL and documented in TEV-1463 Rev. 0 (INL, 2012). In addition, this report includes updated information on codes and standards for high temperature gas cooled reactors (HTGRs) at the time of writing, as well as additional information on leak-before break (LBB) issues as applied to HTGRs, and foreign codes and standards.
Current interest expressed by industry in HTGR plants, particularly modular plants with power up to about 600 MW(e) per unit, has prompted NRC to task PNNL with assessing the currently available literature related to codes and standards applicable to HTGR plants, the operating history of past and present HTGR plants, and with evaluating the proposed designs of RPV and associated piping for future plants.