NEA Primary Coolant Loop Test Facility (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, was also be covered. A further topic addressed 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 were also considered in the test programme. Further investigation addressed boron precipitation processes in the core following large break loss of coolant accidents.

The program included eight integral experiments at the PKL test facility covering the following topics.

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

** The tests on fast cooldown transients were 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 held from 15 to 19 October 2012 at the OECD Conference Centre attracted 65 participants from 14 countries and 2 international organisations. 45 presentations were given covering the general overview of PKL and ROSA programs, the analyses of the Counterpart Test in PKL & ROSA/LSTF facilities, the results and analyses related to PKL-2 / ROCOM tests, the results and analyses related to other PKL and ROSA tests, Analytical studies on Core Exit Temperature (CET) behaviour and general analyses related to PKL-2 and ROSA-2 tests including application to reactor case. The conclusion of this workshop prepared by the Session Chair together with the final summary integration report of these two projects will be issued as public CSNI report in 2013.

A 3.5 years follow-up project PKL Phase 3 had started 1 April 2012.


Belgium, Czech Republic, Finland, France, Germany, Hungary, Japan, 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 updated: 21 October 2013