The “Stuttgart Declaration” by 20 engineering scientists, in which they demand the continued operation of nuclear power plants in Germany, caused a great deal of political turmoil. In an interview with FOCUS Online, institute director André D. Thess, one of the initiators, explains not only how we will get through the winter this year, but also the fundamental weaknesses of German energy policy.

FOCUS Online: Mr. Thess, are the three still running German reactors, which are currently the subject of the political dispute, still safe?

André Thess: The reactors are technically mature pressurized water reactors of the KONVOI type, formerly developed by Siemens KWU. They are subject to so-called periodic safety reviews (PSÜ). The fact that they are regularly in the top ten of international annual electricity production speaks for the quality of these systems.

What makes them so safe from an engineering point of view?

Thess: They are safe because they have: (1) negative feedbacks that dampen the chain reaction as reactor temperatures rise, (2) four-train emergency cooling systems, (3) bunkered emergency feed buildings with additional water and diesel supplies, and diesel generators , (4) double-walled containment and emergency system as protection against earthquakes, aircraft crashes and flood events, (5) additional devices for protection against hydrogen explosions, so-called passive recombiners, (6) protection of the containment against overpressure by so-called filtered pressure relief systems.

professor dr André Thess (born 1964) is Director of the Institute for Technical Thermodynamics at the German Aerospace Center (DLR) and Professor of Energy Storage at the University of Stuttgart. His research focuses on thermal energy storage and electromagnetic process and high-temperature measurement technology. In teaching, Professor Thess advocates mathematical accuracy and comprehensibility in the use of the concept of entropy with his book “The Entropy Principle – Thermodynamics for the Dissatisfied”.

Who actually checks the safety of the nuclear power plants?

Thess: The TÜV organizations are responsible for testing the safety of nuclear facilities in Germany. TÜV Süd, for example, has no safety concerns about Isar 2.

In terms of medium- and long-term energy security, would it be enough to extend the service life of three reactors?

Thess: According to the Intergovernmental Panel on Climate Change (IPCC), a CO2-neutral energy supply can consist of solar energy, wind energy, nuclear energy and fossil energy sources with CO2 separation (CCS). In my opinion, a mix of technologies is necessary for the environmentally friendly, reliable and inexpensive energy supply in Germany. In my opinion, it would be surprising if the historical random number “three reactors” came out.

When it comes to European solidarity, shouldn’t every country first use the energy sources it has before Spain, for example, is supposed to save gas for Germany?

Thess: In a market economy, officials don’t decide where companies source gas, iron ore, smartphones or bananas for their customers. This regulates the interplay of supply and demand. In this respect, the use of domestic or foreign energy sources has nothing to do with solidarity, but with functioning markets and trade relations.

How do you feel about the possibility of extracting German gas, be it at sea or on land through fracking?

Thess: Germany’s current energy policy is inconsistent: we are phasing out nuclear energy but importing nuclear power. We do not want fracking, but plan to import natural gas from this technology. In my opinion, this contradiction can be eliminated by using nuclear energy alongside sun and wind on the one hand, and using fracking in Germany as a bridging technology on the other.

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You and your colleagues who signed the Stuttgart Declaration are critical of the energy transition. What are your biggest concerns?

Thess: Everyone who signed the Stuttgart Declaration considers the reduction of global CO2 emissions to be an important task. We firmly reject the accusation that we are opponents of the energy transition. We criticize the current German energy policy for the lack of openness to technology in the form of the exit from climate-neutral and resource-efficient nuclear energy and the ban on CCS. Second, a majority of us criticize the low climate-economic efficiency of measures such as the EEG and subsidies for electric cars. Third, we regard the discussion about small-scale measures such as the ban on domestic flights or the introduction of meat-free canteens as counterproductive for the acceptance of climate protection.

Do we need – even from a technical point of view – something like a revision of the energy transition?

Thess: In my opinion, we need an energy policy that is open to technology and a market economy that promotes individual responsibility and entrepreneurial freedom. That would be a revision of previous policies, both technically and economically.