American Nuclear Society

Home / Publications / Journals / Nuclear Technology / Volume 175 / Number 3

Effects of Break Size on Direct Vessel Injection Line Break Accidents of the ATLAS

Ki Yong Choi, Hyun Sik Park, Seok Cho, Kyoung Ho Kang, Nam Hyun Choi, Won Pil Baek, Yeon Sik Kim

Nuclear Technology / Volume 175 / Number 3 / September 2011 / Pages 604-618

Technical Paper / NURETH-13 Special / Thermal Hydraulics /

The direct vessel injection (DVI)-adopted power plant APR1400 considers a DVI line break among the analyzed small-break loss-of-coolant accidents in safety analysis. The first-ever integral effects test database for various DVI line break sizes from 5% to 100% was established with the Korea Atomic Energy Research Institute's Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS) test facility. This database enhances our physical understanding of the major thermal-hydraulic behaviors of the APR1400 during DVI line break accidents, and it can also be used to examine the prediction capabilities and identify any deficiencies in the existing best-estimate safety analysis codes. Effects of the break size were experimentally investigated, and the best-estimated MARS code was assessed against the experimental database. On the whole, the prediction of the MARS code shows a good agreement with the measured data. However, the code predicted a higher core level than the data just before a loop seal clearing occurs, and it also produced a more rapid decrease in the downcomer water level than the data. These disagreements are the expected consequence of uncertainties in predicting countercurrent flow or condensation phenomena in a downcomer region. The present integral effects test data will be used to support the present conservative safety analysis methodology and to develop a new best-estimate safety analysis methodology on the DVI line break accidents of the APR1400.

Questions or comments about the site? Contact the ANS Webmaster.