NEA Primary Coolant Loop Test Facility (PKL-4) Project

The PKL-4 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 under two-phase flow, boron dilution and precipitation and on cool-down procedures.

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 Erlangen, 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), the PKL‑2 Project (2008‑2011), and the PKL‑3 Project (2012‑2016) which included tests run in the PMK facility in Budapest, Hungary and in the PACTEL facility in Lappeenranta, Finland.

Also in the current programme, in addition to tests to be run in the PKL facility, additional tests will be run in the PMK facility in Budapest, Hungary and in the PACTEL facility in Lappeenranta, Finland.
The PKL Phase 4 project started on 1 July 2016 and will end on 30 June 2020. It will focus on parametric studies on thermal-hydraulic procedures for model development and validation of thermal-hydraulic system codes, and on experimental verification of cool-down procedures and operation modes for different incidents and accidents.

The first category addresses test subjects related to current safety issues that either suffer from the lack of a dedicated database for analysis and validation of computer codes or from uncertainties in the safety evaluation stemming from open issues or questions. The extension to already existing databases related to these subjects is the foremost goal of this first category experiments.

The second category of tests mostly contains transient tests either on test subjects already investigated in the former OECD/PKL-projects as answers to questions that could not yet finally be completed or on subjects which represent current topics from the international debate on PWR safety.  Complementary tests in PMK and PWR PACTEL are also considered in the test programme.

Finally, two test subjects remain open to be decided by the programme partners following the results of preceding experiments (either confirmatory test or test addressing specific participants' request).


Belgium, Czech Republic, Finland, China, France, Germany, Hungary, Japan, Korea, Russia, Spain, Sweden, Switzerland and the United States.

Safety organisations, research laboratories and industry from the 14 countries are supporting the PKL project. On the German side, the project is supported by the Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) and by AREVA NP.

Project Period

July 2016 to June 2020


EUR 4.78 million

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Last updated: 16 October 2017