Special problems in modeling the high flux isotope reactor with RELAP5.

摘要

A RELAP5 thermal-hydraulic model of the High Flux Isotope Reactor (HFIR) has been developed to perform calculations for the HFIR Final Safety Analysis Report (FSAR). Modeling problems specific to the HFIR exist because it is a liquid-solid system and experiences low (often subatmospheric) pressures during a loss-of-coolant accident (LOCA). The problem discussed include (1)adequately modeling depressurization of the system, (2) predicting the occurrence of internal choking of the primary coolant flow, and (3) modeling the effects of pump cavitation, which occurs for some LOCAs. An accurate model of the system stiffness has been developed and tested using the RELAP5 control systems capability and seems to be adequate for predicting the behavior of the primary coolant system during a LOCA. The problems with internal choking and pump cavitation have been addressed, but are not yet resolved. 11 refs., 7 figs.