The International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS) has been in place for more than 20 years, and so far in the countries of North-East Asia: PR China (including Taiwan), Japan and the Republic of Korea. The conference focuses primarily on thermo-hydraulics, that is, the flow of liquids and the transfer of heat and mass in nuclear power plants.

The presentations on this year's NUTHOS conference focused on the following areas:

- Thermo-hydraulics of the containment,

- advanced reactors,

- reactors with liquid metals,

- experimental thermo-hydraulics,

- computational fluid dynamics,

- severe accidents,

- two-phase flows and heat transfer,

- power plant management,

- Approaches on several scales and with different physics.

Participation at the conference was interesting mainly due to the mass participation of Chinese researchers and experts. China is currently the state in which the most of new nuclear power plants are being build and where research in the field of nuclear energy is the most intensive and covers a broad area.

My overall assessment of the content of the papers is that the prediction of phenomena in experimental installations and systems of nuclear power plants in which fluid flow, heat transfer and mass transfer is present, and which is based on numerical solving of the basic equations and additional constitutional relations is still not satisfactory, although this would be expected due to the development of computer technology. In particular, this target is remote for nuclear systems in the right power plants. For this reason, it is necessary to continue this type of research, which takes place at the JSI within the framework of European projects and programs and ARRS projects. In this regard, one should not rely solely on the further development of computer technology, but it is necessary to develop physical models based on the phenomenological understanding of the phenomena under consideration.

At the conference I presented the paper: "Experiment on light gas layer erosion and a small-scale MCTHBF containment experimental facility" by H.Gong, Y. Wang, Y. Zan, P.Li (all Nuclear Power Institute of China, China) I. Kljenak (IJS), E.Studer (CEA, France), A.Bentaib (IRSN, France) and N.Mechitoua (EdF, France).

On the last day of the conference, I attended a professional excursion to the Hayiang nuclear power plant, where are planed six units of nuclear reactors Westinghouse AP1000. The first unit is already connected to the grid, while the second unit is scheduled for the next year.

The NUTHOS-12 Conference (12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety), which took place from 14 to 18 October 2018 in Qingdaou (PR China), was attended by dr. Ivo Kljenak from the Reactor Engineering Division, IJS.