NEA Primary Coolant Loop Test Facility (PKL-3) 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), the PKL-1 Project (2004-2007) and the PKL-2 Project (2008-2011)

In addition to tests to be run in the PKL facility, additional tests will be run in the PMK facility in Budapest, Hungary, in the PACTEl facility in Lappeeranta, Finland and in the ROCOM facility in Rosendorf, Germany

The follow-up project PKL Phase 3 has started April 1st, 2012. The PKL phase 3 tests will investigate safety issues relevant for current PWR plants as well as for new PWR design concepts by means of transient tests under postulated accident scenarios and systematic parameter studies on thermal hydraulic phenomena.

The first category includes tests addressing current safety issues related to beyond design basis accident transients with significant core heat-up, i.e. station blackout scenarios or loss of coolant accidents in connection with failure of safety systems. Without any adequate accident management (AM) procedures the postulated courses of events would lead to a severe accident scenario with core damage. In the tests the efficiency of very late initiated AM-measures shall be demonstrated and thereby the safety margins shall be explored. Both scenarios will be connected with an assessment of the performance of the Core Exit Temperature (CET) which is used as criterion for the initiation of AM-measures involving emergency operating procedures and/or severe accident management measures.

Also with respect to current safety issues, events in cold shut down state i.e. failure of residual heat removal (RHRS) will also be covered by the proposed PKL-3 test programme. Findings from the former PKL and PKL-2 projects on thermal hydraulic phenomena (e.g. pressure evolution following failure of RHRS, boron dilution) will now be compared to transients test conducted with open RCS.

The second category of tests addresses some test subjects already investigated in the former PKL projects and that could not yet finally be completed. Parameter variations from tests conducted in the PKL-2 programme are implemented in the PKL-3 program, either to provide an extension to already existing data bases on cool down procedures under asymmetric natural circulation or to determine the sensitivity of boron precipitation in the core following LB-LOCA to specific parameters. Complementary tests in ROCOM, PMK and PWR PACTEL are also considered in the test programme.

Two meetings were held in 2015 and in November, the final tests were completed. A counterpart test was performed to compare with a test conducted in the ROSA facility in Japan, and a further counterpart test is being considered by the ATLAS project to reproduce a PKL-3 test.

With all tests completed, the operating agent, Areva, is progressing to the analysis of the results and the production of the final report targeted for completion in July 2016. The project participants and the operating agent have completed discussions on a follow-on project based on known gaps of knowledge which they hope will start around mid-2016. There will be a benchmark workshop with two PKL-3 benchmarks outcomes in collaboration with an ATLAS project benchmark activity in Pisa on 13-16 April 2016.

Participating countries

Belgium, Czech Republic, Finland, France, Germany, Hungary, Italy, Japan, Republic of Korea, Spain, Sweden, Switzerland, United Kingdom, and 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 2012 to April 2016


EUR 3.9 million

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Neil Blundell:

Last reviewed: 2 February 2016