Every degree counts

Measuring the Danube water temperature at the Paks NPP site

The Paks nuclear power plant in Hungary needs cooling water from the Danube for the four operating and two future reactors.
In the past few years, as Hungary was facing several extreme weather occurrences. In 2018, as the temperature raised, the Hungarian NGO Energiaklub submitted a freedom of information request to the Hungarian National Atomic Agency to find out how the increased temperature influences the daily operation of Paks NPP. Since the authority did not provide the information, Energiaklub travelled to Paks to measure the temperature of Danube.
The results of measurements upstream from the nuclear plant showed the water temperature to be 25-26°C. Downstream, however, the temperature rose to above 30°C at several points. For Paks, the cut-off is set at 30°C.
Shortly after Energiaklub published the findings and a video, the company running the nuclear plant sent its official water temperature data. On the day Energiaklub has measured over 30°C, the official thermometer measured 28.42°C. The nuclear plant registered the highest water temperature, 29.88°C, at the beginning of August. This is only 0.12°C lower than the temperature at which the NPP must be stopped in order to protect life in the river. The Danube is a very important ecosystem for Europe and has to be preserved all along its course.
This event did not only reveal differences in the temperature measurement results that need to be investigated, but also highlighted another important weakness of the system - the question of transparency.
Therefore, in this project, we want to establish an independent quality control on the Danube water temperature monitoring during the next one or two years.

Laufzeit: 2021.
Foto von Donau/Fotograf Mihaly Koles


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  • WUA, David Reinberger