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Analysis of CRDM Nozzle Break at the ATLAS Facility with 3D Components in MARS-KS and TRACE (NUREG/IA-0552)

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Publication Information

Manuscript Completed: December 2023
Date Published: June 2025

Prepared by:
Hyunjoon Jeong*, Taewan Kim*, Jae Soon Kim**, Dong Gu Kang**

*Department of Safety Engineering, Incheon National University (INU)
119 Academy-ro, Yeonsu-gu,
Incheon, 22012, Republic of Korea

**Korea Institute of Nuclear Safety (KINS)
62 Gwahak-ro, Yuseong-gu,
Daejeon 34142, Republic of Korea

A. Hsieh, NRC Project Manager

Division of Systems Analysis
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

Prepared as part of
The Agreement on Research Participation and Technical Exchange
Under the Thermal-Hydraulic Code Applications and Maintenance Program (CAMP)

Published by:
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

Availability Notice

Abstract

The Korea Atomic Energy Research Institute (KAERI) operates the Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS), a facility designed to simulate transient and design basis accidents based on the Advanced Power Reactor 1400 (APR1400). Recently, a loss of coolant accident (LOCA) test at the top of the reactor pressure vessel (RPV) was conducted at ATLAS. This aimed to investigate the impact of losing safety injections (LSI) and evaluate accident management (AM) actions during such an event. An analysis of the ATLAS Control Rod Drive Mechanism (CRDM) nozzle break experiment was conducted using the MARS-KS and TRACE codes alongside their respective 3D components. The primary objective of this study is to investigate thermal-hydraulic phenomena during a small break LOCA at the RPV upper head with LSI. Additionally, it aims to assess the predictability of system analysis codes post AM actions during the test. The results are compared and discussed not only against experimental data but also with the calculation results of the VESSEL component, a 3D aspect of TRACE.

Page Last Reviewed/Updated Monday, June 16, 2025