Identification of Two-Phase Flow Regimes in Unstable Natural Circulation Using TRACE and RELAP5
2012 (English)In: Proceedings of The 9th International Topical Meeting on Nuclear Thermal-Hydraulics, Operation and Safety (NUTHOS-9), 2012, N9P0062- p.Conference paper (Refereed)
The paper is concerned with validation of system thermal hydraulic (STH) codes TRACE, RELAP5 and identification of flow regimes against experimental data from low pressure CIRCUS-IV facility (Delft University of Technology, The Netherlands) on two-phase natural circulation flow instability. In previous work , RELAP5 was validated against the CIRCUS data. The study showed that RELAP5 can predict relatively well the instability in the system. Later, the instantaneous two-phase flow regime identified in simulations was compared with the flow pattern recorded by high-speed camera. It suggested that the flow regime was often misidentified by the code. In this paper, we focus on the effect of flow regime treatment on two-phase flow instability prediction. Both codes are implicitly using concept of flow regime map and correlations obtained for steady state flow conditions. RELAP5 and TRACE have quite different approaches to the treatment of two-phase flow regimes. While RELAP5 has more elaborate flow regime map, TRACE is using an interpolation between bubbly-slug and annular mist flow regimes to simulate all intermediate regimes. Analysis of the codes prediction results sheds new light on the importance of the flow regime in STH codes. We also provide discussion on sensitivity of the predicted unsteady flow to parameters of flow regime treatment.
Place, publisher, year, edition, pages
2012. N9P0062- p.
System code, two-phase instability, flow regime
Other Engineering and Technologies
IdentifiersURN: urn:nbn:se:kth:diva-165394OAI: oai:DiVA.org:kth-165394DiVA: diva2:808232
9th International Topical Meeting on Nuclear Thermal-Hydraulics, Operation and Safety (NUTHOS-9), Kaohsiung, Taiwan, September 9-13, 2012
QC 201505062015-04-272015-04-272015-05-06Bibliographically approved