Experiment investigation on pool boiling of the modelled spent fuel tube bundle under partial dry-out conditions. (November 2018)

• Record Type: Journal Article
• Authors: Lu, Daogang; Gao, Shang; Zhong, Yuhang; Wang, Han; Cao, Qiong; Xiong, Zhenqin
• Is Part Of: Annals of nuclear energy. Volume 121(2018)
• Page Start: 461
• Page End: 467
• Publication Date: 2018-11
• Subjects: Spent fuel pool -- Dry-out -- Two-phase flow -- Heat transfer coefficient -- Safety criterion; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2018.08.013
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: Experiment on pool boiling of a spent fuel bundle under dry-out condition. Different exposed percentage of the bundle was considered. Heat transfer coefficient of the bundle and two-phase flow pattern were studied. Rod temperature won't exceed 400 °C when the exposed percentage reached 45%. Abstract: Under normal conditions, the decay heat of the spent fuel can be removed by the forced-circulation cooling system of the spent fuel pool. In the case of a system failure, the water level in the pool will be gradually decreased owing to an evaporation of the water, and the spent fuel bundles may be exposed to air, i.e., a dry out. Since the Fukushima accident, researchers have been paying significant attention to the safety of the spent fuel under such dry-out conditions. To study the boiling behaviour of the spent fuel bundle under a partial dry-out condition, an experimental investigation has been carried out. A newly constructed 9 × 9 heated tube bundle with the same geometry as the prototype spent fuel assembly in an AP1000 was used as the test section. Two-phase flow patterns were recorded. The heat transfer coefficient of the rods in different locations was obtained. A temperature fluctuation was observed at the beginning of the dry-out process mainly owing to the reduced heat transfer effectiveness of the steam. Although the maximum wall temperature (about 570 °C) exceeded the safety criterion when 50% of the tube bundle at the top end was exposed to air, the bundle maintained its integrity.