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Thermal Hydraulics

Thermal hydraulics for fission reactors

In the field of thermal hydraulics, the R&D activity of the research team has been focused in technology transfer to the industry and administration. The Research Team has experience in:

  • Improvement of the safety of nuclear power plants using TH system computer codes (e.g. RELAP5, TRACE)
  • Support to operation and engineering
  • Assessment of uncertainties
  • Contribution to code maintenance and assessment by participating in international benchmarks
  • Knowledge transfer

ANT has a long cooperating experience (expanding for more than 20 years) with Ascó and Vandellòs II nuclear plants, giving support to operation and plant engineering by means of thermal-hydraulic (TH) analysis using TH codes distributed by the Consejo de Seguridad Nuclear, (CSN, Nuclear Safety Council, the Spanish regulatory body). In this sense ANT members have a large expertise in the use of codes like RELAP5 and TRACE.


More than 400 Nuclear Power Plants are currently operating in the world. The safe operation of such plants is an important issue and a concern for citizens. Science is contributing to it by developing a deep and reliable knowledge of plant behaviour under normal and abnormal conditions.

Simulating such behaviour is the main goal of the thermal hydraulic section of ANT. In order to predict and master this behaviour, an important know-how in thermal-hydraulics is required as well as other skills like neutronics, material performance, and controls.

Nuclear safety experiments constitute an essential part of thermal-hydraulic R&D. These experiments are performed in non-nuclear lower scale facilities designed to reproduce accidental scenarios. The facilities are rather expensive and so usually maintained through international efforts.

ANT participates in a number of OECD projects, in facilities located in Germany, Japan and Korea involving a large number of participants of several countries. The main interest of these experiments is that parameters that are relevant from the safety point of view can be measured and analysed later on, so that we can understand what happened and simulate it.

Simulating a full size power plant is a complex task that requires experienced users. A validation process is unavoidable.
At ANT, we have developed a novel methodology to scale up simulations of integral experiments up to the full plant size. In this way, we can predict the behaviour of nuclear reactors in hypothetical accidental scenarios with a high degree of confidence.

Group Leader: Francesc Reventós