Application of the ANT assessment methodology for validating LOCUST 1.2 thermal-hydraulic code

Nuclear power plants play a critical role in providing clean and sustainable energy. Ensuring the safety of these plants is of utmost importance to the nuclear industry. In this regards, thermal-hydraulic computer codes are essential for the simulation and understanding of the behavior during both normal and accidental conditions. In this context, LOCUST 1.2 is a newly developed thermal-hydraulic code by China General Nuclear, which aims at simulating the steady-state and accidental behavior of HPR-1000, a Pressurized Water Reactor design. This paper presents the validation of LOCUST 1.2 using the Advanced Nuclear Technologies assessment methodology from the Universitat Polit & egrave;cnica de Catalunya . The validation focuses on a nodalization created for the Large Scale Test Facility from the Japan Atomic Emergency Agency. In particular, four tests from the OECD/NEA ROSA 1 and 2 projects were selected. The selected tests encompass scenarios such as Anticipated Transient Without Scram, Intermediate Break Loss-Of-Coolant Accident, Steam Generator Tube Rupture, and Main Steam Line Breaks. The ANT-UPC methodology provides a comprehensive phenomenological assessment combining qualitative and quantitative analyses with the help of Best Estimate Plus Uncertainty calculations. All four tests are divided in phenomena through a Phenomena Identification and Ranking Tables (PIRT) to then perform the assessment of each phenomena individually, finally yielding an assessment matrix. Due to length constraints, this article only presents the detailed description of four key phenomena. However, the full PIRT table together with the assessment for each phenomenon is provided. The overall findings indicate that LOCUST 1.2 demonstrates a good capability to accurately reproduce most of the phenomenology observed in all four tests.