SESAR Thermal-Hydraulics (SETH) Project
Joint project

Scheme of the PKL facility, Framatome GmbH.


The SESAR Thermal-hydraulics (SETH) Project began in 2001 and consisted of thermal-hydraulic experiments in support of accident management, which were carried out at facilities identified by the Committee on the Safety of Nuclear Installations (CSNI) as those requiring international collaboration to sponsor their continued operation. (Note: SESAR is the acronym for the CSNI Senior Expert Group on Safety Research.)

SETH phases

First phase (2001-2006)

The first phase of the project covered two aspects of accident management:

  • countermeasures for two types of pressurised water reactor (PWR) accidents carried out at Framatome's Primär Kreislauf (PKL) facility in Erlangen, Germany
  • gas flow distributions relevant to in-reactor containments (with focus on simulated hydrogen distribution) carried out at the PSI PANDA facility near Zurich, Switzerland.

Second phase (2007-2010)

The second phase (SETH-2) started in 2007 with the aim of resolving key computational issues for the simulation of thermal-hydraulic conditions in reactor containments. SETH-2 made use of the Paul Scherrer Institute's (PSI) passive decay heat removal and depressurisation test (Passive Nachwaermeabfuhr und DruckAbbau Testanlage (PANDA)) facility and the Commissariat à l’énergie atomique's (CEA) Mitigation and Stratification (MISTRA) facility.

The aim of the project was to generate high quality experimental data to be used for improving the modelling and validation of computational fluid dynamics (CFD) and lumped parameter (LP) computer codes designed to predict post-accident containment thermal-hydraulic conditions. The unique and complementary instrumentation used in the PANDA and MISTRA facilities and the different size and configuration of the two installations have contributed to address a variety of measured parameters, configurations and scale, thus enhancing the value of the data for code applications. Relevant containment phenomena and separate effects were studied in the programme, including the effects of jets, natural convection, the effect of containment coolers, the effect of sprays etc. The experimental data obtained not only support CFD and LP code validation for current operating reactors but also simulate conditions specific to advanced reactor designs.

The PANDA test series included:

  • low momentum vertical fluid release test series (ST1)
  • low momentum horizontal fluid release test series (ST2)
  • containment spray test series (ST3)
  • containment cooler test series (ST4)
  • recombiner test series (ST5)
  • rupture disk test series (ST6)

The MISTRA test series included:

  • establishment of initial gas stratification series (INITIALS)
  • natural circulation induced by wall condensation series (NATHCO)
  • steam jet impingement on walls series (IMPING)
  • low momentum air or steam injection series (LOWMA & LOWMS)
  • spray effect on stratification series (SPRAY)

The scaling effects between the two facilities was studied in comparing LOWMA3, LOWMA4 and ST1-7 tests results

The tests were run between October 2007 and November 2010. A concluding seminar was held from 13-14 September 2011 at NEA headquarters.

Project data

SETH/PKL data package, SETH/PANDA data package and SETH-2 data package are available upon request to OECD NEA members. 

External publication

Interaction of a light gas stratified layer with an air jet coming from below: large scale experiment and scaling issues – E. Studer, J. Brinster, I. Tkatschenko, G. Mignot, D. Paladino, M. Andreani – XCFD4NRS-3 (3rd Workshop on Experiments and Computer Fluid Dynamics for Nuclear Research and Safety), 14-16 September 2010, Washington, DC, USA, doi:

  • First phase: Belgium, Czechia, Finland, France, Germany, Hungary, Italy, Japan, Korea, Spain, Sweden, Switzerland, Turkey, United Kingdom and United States.
  • Second phase: Czechia, Finland, France, Germany, Japan, Korea, Sweden, Switzerland and Slovenia.
Project period
  • First phase: 2001-2006
  • Second phase: 2007-2010
  • First phase: USD 4.7 million
  • Second phase: USD 3.2 million