COMPARISON OF THERMAL HYDRAULIC ANALYSIS METHODS (CODES) FOR THE UNIVERSITY OF FLORIDA TRAINING REACTOR (UFTR)

摘要

Research reactors, such as those sited at universities and national laboratories around the world, operate in a significantly different regime than do light water reactors for power production. Research reactors typically operate at or near atmospheric pressure, compared to the 70+ atmospheres of pressure in power reactors. Further, boiling (including sub-cooled boiling) is generally avoided in the research reactor field, in stark contrast to LWRs, particularly BWRs. As a consequence, research reactors often operate with wider safety margins, allowing for more flexibility in their siting and use as training and educational tools. One drawback of these large safety margins is the reduced impetus for modern code development. The thermal hydraulics of power reactors is often analyzed using modern tools such as RELAP5/MOD3.3 and TRACE V5.0 (NRC), RELAP5-3D (INL), and RELAP7 (in development). Meanwhile, research reactors are often analyzed with older tools such as PLTEMP (ANL, 1980) and PARET(INL, 1969). The University of Florida Training Reactor (UFTR) is a 100 kW Argonaut- type research reactor going through its 20-year NRC relicensing process. Supporting a comprehensive reworking of the safety analysis, a detailed review of the thermal hydraulic hydraulic analysis has been performed evaluating the best methodologies for modeling in this reactor. Comparisons are made between code results from research reactor specific codes (PLTEMP and PARET) and results from modern, validated, power reactor codes (RELAP) and validated against operational data from the UFTR. A recommendations for preferred codes for research reactors with similar flow regimes is made.