Multidimensional prediction of the effect of flow blockage in SCTF S1-01 experiment using MARS-KS code

• Published in: Annals of nuclear energy 2021-03, Vol.152, p.108028, Article 108028
• Main Authors: Bang, Young Seok, Lee, Joosuk, Shin, Andong, Oh, Deog-Yeon
• Format: Article
• Language: English
• Subjects: Flow blockage; MARS-KS code; Multidimensional modeling; Reflood; SCTF experiment
• ISSN: 0306-4549; 1873-2100
• DOI: 10.1016/j.anucene.2020.108028

•SCTF reflood experiment with flow blockage can be predicted by the MULTID model.•Excessive water entrainment from the core in calculation affects accuracy.•Increase in PCT higher than 50 K is expected for the postulated 80% blockage case.•Adjustment of the interfacial drag at the core can improve the predictability. The present paper discusses the predictability of the MARS-KS code regarding multidimensional thermal-hydraulic behavior involving 60% blockage within the reactor core based on the experiment, S1-01 of SCTF. An input model simulating the reactor pressure vessel (PV) in a multidimensional manner and the author's flow blockage model are applied. Predictability of the MARS-KS code is assessed including the conservatism in PCT. The major difference is identified as entrainment of excessive water by steam generated from the core, accumulation of water in the upper plenum, and partial reintroduction of the water into the core by gravity, which are supported by the multidimensional distribution of void fraction and superficial velocity. The effect of blockage on flow in the PV and PCT is evaluated through calculation of hypothetical unblocked case and 80% blockage case. It is also investigated whether the prediction can be improved by adjusting the interfacial drag at the core.