Session: FSI-01-01 Thermal Hydraulic Phenomena with Vessels, Piping and Components

Paper Number: 106539

106539 - Evaluation of Temperature Distribution Induced by Turbulent Penetration in the Re-Branched Line of Reactor Coolant Systems 

Piping failures due to thermal stratification and thermal fatigue have been widely reported in normally stagnant non-isolable reactor coolant system (RCS) branch lines. In United States, EPRI issued MRP-132, 146, and 146S which provide common industry approaches to thermal fatigue problems in RCS branch lines in response to U.S.NRC bulletin 88-08. Those documents present the screening out and threshold temperature criteria for the Non-isolable RCS branch lines which are directly connected to reactor coolant lines such as hot-leg and cold-leg. However, recently, several piping distortions and unexpected temperature distributions of the re-branched line connected to the down-horizontal RCS branch line such as the shutdown cooling line have been reported in Korea. Generally, temperature distribution at those lines are assumed by adopting the thermal decay rule which is well known as 10D-rule in the industry field. In this study, the effects of turbulent penetration on temperature distribution of the re-branched line connected to the down-horizontal RCS branch
line are evaluated based on the computational fluid dynamics (CFD) analysis results. The temperature distribution along the circumferential and longitudinal direction are compared to the real monitoring data and the initiation time and duration of thermal stratification are analyzed. It is a kind of preliminary study to figure out the necessity to develop the additional thermal fatigue evaluation criteria for the re-branched line with diameter less than or equal to
4-inch nominal pipe size.

<Keyword> Turbulent Penetration, Thermal Stratification, Non-isolable RCS Branch Line, Re-branched Line, Computation Fluid Dynamics

 

Presenting Author: Jae-Wook Yu Sungkyunkwan University

Presenting Author Biography: mechanical engineering major
graduate

Authors:

Jae-Wook Yu Sungkyunkwan University
Tae-Young Ryu Sungkyunkwan University
Young-Woo Phi Sungkyunkwan University
Doo-Ho Cho KINS
Sun-Hye Kim KINS
Moon-Ki Kim Sungkyunkwan University
Jae-Boong Choi Sungkyunkwan University