This is the conclusion reached by experts commissioned by the Austrian Environmental Protection Agency after analysing data from a geological research comissioned by MVM Paks II Zrt. in preparation for the expansion of the Paks NPP.

Dr. Kurt Decker, a geologist at the University of Vienna, told Átlátszó that they found significant differences between the geological site report and the resulting site safety report, that the tectonic fault line running under the site should be considered active and capable, and that there is a realistic chance of a devastating earthquake at Paks. Interview.

Atlatszo: What is a tectonic fault line, and why is it important if there is one under the Paks NPP or not?

Dr. Kurt Decker: There are two reasons why tectonic fault lines or geological fault lines are important for such installations, the first one is it could be a so called active fault line that moves episodically, and by moving episodically such fault line would create earthquakes. And an earthquake, the ground shaking of an earthquake would be a threat or hazard that applies to the plant.

The other issue is that if the earthquake is strong enough, it has the possibility to break te surface. So the ground surface which is now pretty flat and buildings, and roads, and whatever are on the surface would be broken by the movement of the fault.

There are examples of active faults around the world, where such movements make steps into previously flat landscape up to a meter height, or shear the surface, and this would destroy all man-made structures that are situated on the top of this fault line.

What kind of research is need to be done to explore the possible presence of such a fault line in vicinity of nuclear power plants?

There is a whole series of geological and geophysical investigations that needs to be done to exclude the presence of such fault lines – it is not very easy to exclude them because such strong earthquakes are rare.

If we dont have records in our history that such earthquakes occured, this is not because there are no such earthquakes possible in an area, this is rather because our history looks back for a couple of hundred years, so we have written records for – I dont know how Hungary is, but in Austria prior to the year 1200 AD we dont find any records about earthquakes in a written way.

Typically these very strong earthquakes occur once in thousand years, two thousand years, so we are simply lucky in the last hundred years in Austria not to see something like that, and you in Hungary probably as well.

You reviewed the geological research that was done in Paks before the expansion of the nuclear power plant. What did you find out?

We looked at the research results which were provided by the Hungarian geological and seizmological and geophysical scientific community.

This is summarized in a very thick volume called the Geological Site Report which has couple of thousand pages.

By looking at that we learned that there were thorough investigations around the site to identify these fault lines with geophysical methods, with geological methods, and there is convincing evidence in these documents that the existing Paks NPP and the future Paks2 NPP site is sitting on an active fault line: this is also one of the conclusions of this document, the Dunaszentgyörgy-Harta fault zone.

This is a fault zone which is about 1 kilometer wide, and extends below the existing power plant, and into the site where Paks2 should be constructed.

When this became public in 2017 that this fault line runs right below the power plant, the scientists who conducted the research claimed that while there is indeed a fault line it is not „capable”. What is a capable fault line and why do they think this fault line is not capable?

A capable fault is capable to disrupt the surface. In addition to the earthquake shaking you have a step or shearing of the earth surface, this is referred to as a capable fault.

As we have read the geological report they dont exclude the capable fault, and there is a part of the report where they show an excavation, a digging of a 80 meter long trench, excavated the youngest sediments of the Danube, which has an age of 19-20 thousand years, and they clearly documented faults that reach up into these very young sediments.

They provide evidence with pictures, with profiles, with geological descriptions that these are actually faults that ruptured the surface 19-20 thousand years ago. So I think that the Hungarian scientists were aware of this.

When I interviewed the scientists who were conducting and supervising this research, they still said that this is not a capable fault, it has no capability to disrupt the surface. Does it?

It was able to move the ground 19-20 thousand years ago, and it is very difficult to assume that there is a geological switch and the fault now is turned off, and it would never move the surface again.

How come then that they classified this site suitable for a nuclear power plant?

As far as we learned from the Hungarian legislation and regulations for nuclear safety, it is necessary that the possibility of a permanent ground displacement, what is a capable fault, needs to be excluded by scientific evidence for the site.

This is a requirement to the site to be considered as a site for a nuclear installation. There are two points in our report: first of all, we say, that okay, there were thorough and deep reaching geological and geophysical investigations, but detailed data about the 1 kilometer wide fault zone is only available from the trench which was 80 meters long.

So there was no adequate investigation of the youngest sediments at the place where the power plant itself should be constructed – the trench was next to the existing power plant.

So we say based on the information we have at the moment that the investigations cannot reliably exclude the existence of a capable fault at the site of Paks II. – which is a Hungarian legal requirement for deciding on the power plant.

The second point is, on the contrary, that data from the trench that is documented in the geological site report, our understanding proves the existence of a capable fault at least in this trench.

Is this data correctly represented in the Site Safety Report derrived from the Geological Site Report?

The Geological Site Report has an enormous number of authors from the geological and geophysical scientific community, as I said it can be weighted in kilos, and it has been condensed into a Site Safety Report by MVM Paks II., which has something like 300 pages.

This Site Safety Report has then been provided to the nuclear authority of Hungary to apply for the site license. As far as we could compare these documents, as non-native speakers so we had to rely on translations, we found very remarkable differences between these documents.

We found that a whole volume of the geological report which was delivered to the future licensee was omitted from the documentation that went to the nuclear authority.

This volume contains paleoseismological evidence of ground breaking faults, surface breaking faults further north from the plant. This does not appear at all in the safety report that MVM Paks II. delivered.

We found diagrams like the map of the fault zone at the site, or below the site, which difer from one report to the other report.

Do you think the Site Safety Report downplayed the probability of a geological incident compared to the Geological Site Report?

This i cannot claim, but we have pointed out very clearly the differences we found. And all these differences are directed to give the impression of less hazard at the site.

This needs to be clarified in discussion with the Hungarian colleagues, and particularly in discussion with the Hungarian nuclear regulator authority. Because so far we do not know if the site license is exclusively based on the safety report delivered by MVM Paks II., or if the nuclear regulatory body also considered the geological report.

Do they talk to you?

This is not my job, I am just a geologist doing the technical stuff, but there is a bilateral agreement between the Republic of Austria and Hungary to discuss matters of nuclear safety on bilateral level regularly, every year, and as far as I know the Austrian body which is responsible for this dialogue submitted a request to Hungary, that this needs to be discussed in a technical discussion with the Hungarian regulator.

Is this a purely legal matter, or do you think there is a real chance of a devastating earthquake at Paks?

As a geologist I think there is a real hazard of an earthquake at Paks. This would be my geological reply. When we read through the geological report, we found evidence for 20-30 severe earthquakes which are all documented to have occured in the near region around Paks in the last 30 thousand years.

This is a very high earthquake density, speaking in terms of geology. There is no reason to assume that this earthquake activity stopped from than to now.

Written by Tamás Bodoky, video by Bence Bodoky. The Hungarian transcript of this interview is available here.

MTI Photo: Tamás Sóki