Nuclear thermalhydraulics

Nuclear Engineering, Second Cycle
1. in 2. year
Hours per week – 2. semester:

Completed undergraduate (first) degree.
Positive result from colloquium (or written exam) is necessary to enter the oral exam.

Content (Syllabus outline)

TBasic equations of fluid mechanics, heat transfer and mass transfer. Fundamentals of thermodynamics of two-phase mixtures of water and steam.
Basic conservation equations of two-phase flow.

Two-phase flow: two-phase flow regimes. Emphasis on two-phase flows in nuclear engineering. Simple methods for analysis of two-phase flow in piping systems.

Models of two-phase flow: time and space averaged basic conservation equations for two-phase flow. Two-fluid models of two-phase flow. Heat transfer between wall and two-phase flow. Boiling in a vertical hot channel. Interphase exchange of matter and energy. Transition from single-phase to two-phase flow: boiling and cavitation in liquids, steam condensation.

Important phenomena in nuclear technology: instability of two-phase flow, critical flow, flow in steam generators, boiling crisis and critical heat flux.

Analysis of transient phenomena in piping systems.

Uncertainties of two-phase flow models.


Bird, Stewart, Lightfoot, Transport Phenomena, John Wiley & Sons, 1960.
Todreas, Kazimi, Nuclear systems. Volume I, Thermal hydraulic fundamentals, Hemisphere Publ. Comp., 1989,
Todreas, Kazimi, Nuclear systems. Volume II, Elements of thermal hydraulic design, Hemisphere Publ. Comp., 1990.
Landau, Lifshitz: "Fluid Mechanics" (Course of Theoretical Physics Vol.6) ,
Ishii, Hibiki, "Thermo-Fluid Dynamics of Two-Phase Flow", Springer, 2006.
Mills, Heat Transfer, Prentice Hall, 1999.

Objectives and competences

Objectives: Understanding and modelling of thermal-hydraulic processes in nuclear power plant systems. Familiarizing with transient phenomena in cooling systems of nuclear power plants.

Competences: Modelling and ability to solve problems; computer skills.

Intended learning outcomes

Knowledge and understanding:
Learn about phenomena in the fields of fluid mechanics, heat transfer and mass transfer, which are important for the operation of nuclear power plants. Emphasis on dynamics of two-phase flow, boiling, forced and natural convection, and transient phenomena in piping systems of nuclear power plants.

Ability to analyse basic thermal-hydraulic phenomena in nuclear power plants.

Ability to assess the quality of mathematical models of various phenomena in two-phase flow.

Transferable skills:
Familiarizing with basic conservation equations of fluid mechanics and heat transfer. Behaviour of two-phase flow of liquid water and steam in piping systems.

Learning and teaching methods

Lectures and exercises, homeworks. Some content will be given in the form of e-lessons, using web-based content for distance learning.


Final written exam
Oral exam
grading: 5 (fail), 6-10 (pass) (according to the Statute of UL)

Lecturer's references

Iztok Tiselj:
1. TISELJ, I, PETELIN, S. First and second order accurate schemes for two-fluid models. ASME - J. fluids eng., 1998, vol. 120 (2), str. 363-368.
2. TISELJ, Iztok, ČERNE, Gregor. Some comments on the behaviour of the RELAP5 numerical scheme at very small time steps. Nucl. sci. eng., 2000, vol. 134, str. 306-311.
Ivo Kljenak:
1. KLJENAK, I., BABIĆ, M., MAVKO, B., BAJSIĆ, I. Modeling of containment atmosphere mixing and stratification experiment using a CFD approach. Nuclear Engineering and Design, 2006, vol. 236, pp. 1682-1692
2. KLJENAK, I., MAVKO, B., Simulation of containment thermal-hydraulics in the Marviken Blowdown 16 experiment with ASTEC and CONTAIN codes. Nuclear engineering and design, 2011, vol. 241, pp. 1063-1070.
3. KLJENAK, I., DAPPER, M., DIENSTBIER, J., HERRANZ, L. E., KOCH, M.K., FONTANET, J. Thermal-hydraulic and aerosol containment phenomena modelling in ASTEC severe accident computer code. Nuclear Engineering and Design, 2010, vol. 240, pp. 656-667