Every degree counts

Measuring the Danube water temperature at the Paks NPP site

The Paks nuclear power plant (NPP) in Hungary needs cooling water from the Danube for the four operating and two future reactors.
In the past few years Hungary was facing several extreme weather occurrences. In the heat wave of 2018, 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 , MVM, the company running the NPP, published 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.
The aim of the project "Every degree counts project" is to establish an independent quality control of the Danube water temperature monitoring in Paks starting in 2022. The first phase of the project summarizes the results on background research of legal aspects, measurement methods and provides comparisons with other countries as well. As a conclusion it can be stated that not only a standardization of methods for temperature measurements for nuclear power plants using cooling water from nearby rivers is missing but there is also an issue with transparency as the results of the temperature measurements and the method of the measurements vary in the studied countries. This confirms the need for independent scientists and NGOs to put a strong focus on transparency of data to allow independent control.