OECD/NEA PKL-2 Project

The PKL-2 test programme is investigating safety issues relevant for current pressurised water reactor (PWR) plants as well as for new PWR design concepts and will focus on complex heat transfer mechanisms in the steam generators and boron precipitation processes under postulated accident situations.

These issues are being investigated by means of thermal-hydraulic experiments that will be conducted at the Primärkreislauf-Versuchsanlage (primary coolant loop test facility) PKL. This facility is owned and operated by AREVA NP and is situated in Erlengen, Germany.

AREVA NP have for a number of years conducted valuable experiments on reactor thermal-hydraulics in the PKL facility, including earlier experiments carried out in the framework of the SETH project (2001-2003) and of the PKL-1 Project (2004-2007).

The first category includes tests addressing the heat transfer mechanisms in the steam generators in the presence of nitrogen, steam and water, in both vertical and horizontal steam generators. Cooldown procedures in the case where steam generators have partly dried out on the secondary side, will also be covered. A further topic will address the heat transfer in the steam generators under reflux condenser conditions (e.g. fast secondary side depressurisation). Fast cooldown transients (with water filled reactor coolant system) such as main steam line break, completed by tests on mixing of hot and cold water in the RPV downcomer and the lower plenum are also considered in the test programme.

Further investigation will address boron precipitation processes in the core following large break loss of coolant accidents. Finally two tests remain open to be decided by the programme partners following the results of preceding experiments (either confirmatory test or test addressing specific participants' request).
The program proposal includes eight integral experiments at the PKL test facility covering the following topics.

  • G1:  Systematic investigation of the heat transfer mechanisms in the SGs in presence of nitrogen, steam and water (2 tests, performed in July and August 2008)*
  • G2:  Cool-down procedures with SGs isolated and emptied on the secondary side (1 test, 3 runs performed in December 2008)
  • G3:  Fast cool-down transients (main steam line break) (1 test, performed in July 2009)**
  • G4:  Accident situation under reflux condenser conditions for new PWR design concept (1 test with two runs, performed in December 2009)
  • G5:  Boron precipitation following large break loss of coolant accidents.
  • G6:  RCS cooldown with void formation in RPV upper head (1 test performed in April 2011)
  • G7:  Counterpart Test with ROSA / LSTF on small break LOCA with Accident Management procedures (1 test performed in July 2011)

* The tests on the heat transfer mechanisms in the SGs in the presence of nitrogen are complemented by tests in the PMK test facility in Hungary for horizontal steam generators.

** The tests on fast cooldown transients are completed by tests at the ROCOM test facility (in Germany) on mixing in the RPV downcomer and the lower plenum.

A concluding Workshop common with the concluding workshop of the ROSA2 project will be organised in October 2012.

It is proposed to have a 3.5 years follow-up project starting in spring 2012.

Participating countries

Belgium, Czech Republic, Finland, France, Germany, Hungary, Japan, Republic of Korea, the Netherlands, Spain, Sweden, Switzerland, the United Kingdom and the United States.

Safety organisations, research laboratories and industry from fourteen countries are supporting the PKL project. On the German side, the project is supported by the utilities (VGB Power Tech Service GmbH), by the Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) and by AREVA NP.

Project Period

April 2008 to September 2011


EUR 1 million per year, with German parties covering 50% of this cost.

Related links

Last reviewed: 14 October 2013