Advances in Transient Thermal-hydraulics in Water Cooled Nuclear Reactors: Main outcomes of the OECD/NEA Specialist meeting

Nuclear reactor thermal-hydraulics (NTH) has developed over the past 60 years as an important discipline for nuclear reactor design, safety analysis and operational support. Despite the achievements in the field, certain issues remain. In order to summarize the current status of thermal-hydraulics and to formulate recommendations to the OECD/NEA Committee on the Safety of Nuclear Installations (CSNI) for activities in the area, the Working Group on Analysis and Management of Accidents (WGAMA) organized a specialists’ meeting on transient thermal-hydraulics in water cooled nuclear reactors on 22-23 March 2022. The key goal of the Specialists Meeting in Nuclear Thermal Hydraulics (SM-TH) is to summarize the status in NTH and to identify the key R&D needs for the Nuclear TH community. This paper describes the key needs identified by the SM-TH for the nuclear for the NTH community related to:  Preserving the competences, expertise and database derived from research investments.  Keeping alive and possibly strengthening the current CFD activities within the NTH area.  Identifying the current issues and limitation in phenomena and simulating them to establish the bases for an innovative NTH, including the attempt to overcome of above-mentioned issues and limitations.  Address other fluids than water and advanced reactors, i.e. not within the scope of the present specialist meeting. Other TH fields might benefit from the water cooled nuclear reactor experience.