Aachen Public Conference (Pressure Vessel Cracking and Tihange 2)

Public Conference in Aachen, Germany on April 13 and April 14, 2018

Audience on Saturday. ©StädteRegion

The public conference on the safety of Belgian Nuclear Power Plants hosted by the StädteRegion Aachen and INRAG  in Aachen, Germany was a huge success.

The aim of the event is to inform the affected population and decision-makers in the federal, state and local authorities about the safety significance of cracks in the reactor pressure vessel of the Belgian nuclear power plant Tihange 2 and to intensify the discourse on further operation among the experts.

The event was separated into different parts: On Friday, we started with a press conference leading to broad media coverage. The afternoon session was dedicated to detailed technical lectures, while on Saturday laymen understandable general considerations on the topic of monitoring aging reactors were held. A detailed program for the whole event can be found here. We also prepared a little brochure to introduce INRAG to the audience.

During the public session on Saturday, more than 400 guests listened to our keynote speakers Simone Mohr (slides), Gergory Jaczko (slides), Rene Boonen (slides), Wolfgang Renneberg (slides), and Nikolaus Muellner (slides). For more information, please have a look at the homepage of the StädteRegion Aachen.

There is an INRAG Nuclear Risk Report, comprising an article by Wolfgang Renneberg and Ilse Tweer on the embrittlement of the reactor pressure vessel. It can be downloaded here.

Material and Links

Program (here)

INRAG Brochure (brochure)

Special issue of the INRAG Nuclear Risk Report (pdf)

Conference Proceedings (pdf)

Friday Session

Presentation Walter Bogaerts (slides, video)

Presentation Jan Peirs (slides, video)

Presentation Ilse Tweer (slides, video)

Presentation Dieter Majer (slides, video)

Saturday Session

Words of Welcome by StädteRegionsrat Helmut Etschenberg and Staatssekretär Dr. Thomas Griese (video)

Presentation Simone Mohr (slides, video)

Presentation Gregory Jaczko (slides, video)

Presentation Rene Boonen (slides, video)

Presentation Wolfgang Renneberg (slides, video)

Presentation Nikolaus Muellner (slides, video)

Doel & Tihange Follow-up

In 2012 thousands of defects were discovered in the reactor pressure vessel shells of the NPPs Doel-3 and Tihange-2, Belgium.

The reactor pressure vessel (RPV) is the is the central component of a nuclear reactor, – for safe operation of the nuclear power plant throughout service life RPV failure has to be excluded, because safety systems are not designed to cope with RPV failure

The independent interdisciplinary expertise network, INRAG, studied the documents on this issue[1][2], which have been published by the Belgian Regulatory Authority FANC[3]. Based on this study INRAG questions the opinion of the operator – which was accepted by the Regulatory Authority – that these defects were manufacture induced and that these defects did not grow during operation. These defects were not observed during acceptance testing after manufacture.

INRAG is not convinced that the reactor pressure vessel structural integrity assessment using an additional shift for the ductile-brittle transition temperature proposed by the operator[4] is conservative. Experimental testing using non-representative sample material as have been performed by the operator Electrabel cannot eliminate the sets of uncertainties concerning the actual material characteristics of the reactor pressure vessels[5].

INRAG recommended in a letter to FANC that these substantive issues be addressed during the regulatory process, which is now in a decisive stage, relating to the potential restart of these reactors.

Because these issues are potentially generalizable, INRAG strongly recommends inspection of all reactor pressure vessels worldwide for unexpected defects outside the weld regions prescribed in the standards for in service inspection. Therefore INRAG will bring their statement to the attention of the IAEA.

[1] FANC , Doel 3 and Tihange 2 reactor pressure vessels, Provisional evaluation report, January 30, 2013 http://fanc.fgov.be/GED/00000000/3300/3391.pdf

[2] FANC, Doel 3 Tihange reactor pressure vessels, Final evaluation report, May 2013, http://www.fanc.fgov.be/GED/00000000/3400/3429.pdf

[3] FANC: Federal Agency for Nuclear Control

[4] Electrabel, Safety case report: Doel 3 – Reactor Pressure Vessel Assessment, 05/12/2012 http://www.fanc.fgov.be/GED/00000000/3300/3390.pdf

[5] Ilse Tweer, Flawed Reactor Pressure Vessels in Belgian Nuclear Plants Doel-3 and Tihange-2. Some Comments on the FANC Provisional evaluation report (January 30, 2013). March 2013, Commissioned by the Greens/EFA Group in the European Parliament, Brussels, http://www.greens-efa.eu/fileadmin/dam/Documents/Studies/Flawed%20Reactor%20Pressure%20Vessels.pdf