On December 28 and 29, 2020, two earthquakes of magnitude 5.2 and 6.3, registered in the Sisak region of central Croatia, caused the automatic reactor shutdown of the Krško Nuclear Power Plant in Slovenia, 80 kilometers from the epicenter of the earthquake and soon more than 100 kilometers from the Italian border. On December 31, the nuclear power plant was restarted: no anomalies were reported and after the safety checks, the plant was declared under control.
The seismic risk is the main concern that has led environmental groups, activists and technicians from Friuli to ask the Italian government for an opinion against the Slovenian request to extend the operation of the nuclear power plant by twenty years from 2023 to 2043. So far, there have been no official responses from either the government or the Ecological Transitional Ministry.
In Italy, the Krško power plant has been under discussion for many years because it is one of the closest to the border with Italy, at a distance that in the event of an accident would require significant safety measures particularly shelters and iodine prophylaxis even in regions of northern Italy, as was recently the case of ISIN, the National Inspectorate for Nuclear Safety and Radiation Protection, prescribes updated national nuclear risk plan.
The Krško plant was built in just six years between 1975 and 1981 and started operations in 1983, almost forty years ago. It is managed by the NEK company Nuklearna elektrarna Krško, which is 50 percent owned by the Slovenian public energy company Gen Energija and the remaining 50 percent is owned by the Croatian public company Hrvatska elektroprivreda (HEP). With its only 700megawatt reactor, the Krško power plant covers just over a third of Slovenia’s and a fifth of Croatia’s electricity needs.
When it was built, the expected life cycle for the facility was 40 years, ending in 2023. In 2015, NEK asked the Slovenian government to extend the activity for another 20 years with a series of interventions to make the facility more modern and safer.
Approval has not yet been granted. The procedures necessary to achieve the expansion of the activity of the plant, and thereby prevent the imminent closure, also include a transboundary EIA, that is, an environmental impact assessment, in which, in addition to Slovenia, neighboring or neighboring states are also involved: Italy, Austria , Croatia, Bosnia, Hungary. On April 14, the consultation phase for municipalities, associations and anyone who would like to submit comments ended.
In addition to beginning the process of obtaining an extension to open until 2043, last year General Energija applied for and received approval from the Slovenian Ministry of Infrastructure to begin designing a new 1100megawatt nuclear reactor called JEK2. The aim is to produce almost 9,000 gigawatt hours per year. According to the ministry, the new reactor should have a service life of 60 years and be operated economically despite an estimated investment of 5 to 6 billion euros.
In recent weeks, Legambiente and some technicians, seismologists and geologists have submitted observations to the Ministry of Ecological Transition, asking the Italian government to take an official position in the crossborder EIA process against extending the life cycle of the plant. Legambiente has worked with Austrian and Slovenian environmental groups to conduct an indepth investigation into the condition of the power plant, which they define as “a now old and obsolete structure built in a seismic area, without a radioactive waste disposal facility”.
According to the seismologists consulted by Legambiente, the Krško nuclear power plant was built near three active faults, Orlica, Libna and Artiče, which in the worst case can generate earthquakes with a magnitude of up to 7.
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One of the Italian seismologists who has been most involved with the Krško facility is Livio Sirovich, who worked in the past for the National Institute of Oceanography and Experimental Geophysics in Trieste and was an adviser to the first Slovenian government that intended to open the facility conclude.
According to Sirovich, Krško is the one with the highest seismicity and seismic risk of all European nuclear power plants. “When the facility was designed, no probabilistic seismic risk studies were conducted,” Sirovich explained. “There wasn’t even a study on the 1917 earthquake.” Several studies estimate that in 1917 there was a magnitude 5.7 earthquake with an epicenter in Krško. It is estimated that in 1880 another earthquake with a magnitude of between 6.3 and 6.5 occurred 60 kilometers from Krško and caused severe damage in the Croatian capital Zagreb.
Sirovich also argues that in the event of an earthquake, the nuclear power plant could experience a “peak ground acceleration” (PGA) that is higher than that considered when the power plant was designed.
According to the seismologist, the power plant is designed for a maximum acceleration of 0.3 g (i.e. three times the acceleration due to gravity), load tests carried out in recent years on the recommendation of the European Union have between 0.8 and 0. 9 g gives the limit above which the structure could be damaged by the release of radioactive material: according to him, this threshold could be exceeded in highmagnitude earthquakes.
During the press conference organized by environmental groups to present the observations submitted to the Ministry of Ecological Transition, Reinhard Uhrig, an activist from Global 2000, an Austrian environmental protection association, said that the documents were submitted by the company that manages the plant Krško has very old data and mentions the Results of the last stress tests not.
“This reduced depiction conveys a beautified image of the more than 40yearold reactor,” says Uhrig. “At the same time, alternatives such as energy saving or renewable energies are presented as unsuitable and uncompetitive due to clearly unfavorable premises. Uptodate international studies on reactor aging and seismic risk must be carried out before a decision is made to extend the life cycle of Krško by another 20 years.
Another issue reported by the associations concerns the lack of a final disposal site for highintensity waste, which the facility has traditionally stored in a tank within a building within the facility.
Legambiente national president Stefano Ciafani has called on the Italian government to oppose the expansion of activities and the duplication of the Krško plant, a position that would be consistent with the mandates of the 1987 and 2011 referendums, which the industry have closed Italian nuclear power. According to Ciafani, nuclear energy is “a historically outdated technology that is being surpassed by more mature and competitive technologies” and above all unsafe due to the “risk of accidents, especially in the seismic area and with insufficient safety systems compared to the foreseeable performance earthquakes in this area”.
The only official position so far against the extension of the life cycle of the power plant was taken by the Regional Council of Friuli Venezia Giulia, which last year at the end of July approved a request to oppose a request presented by the Pact for Autonomy Group Regional Executive.
As Ciafani’s statements show, the position of environmental groups on the Krško power plant is shaped by the general opposition to nuclear power, which has been much discussed in recent weeks due to the energy crisis caused by the Russian invasion of Ukraine. As in the past, the debate is still very lively and strongly polarized between those who call for a rethinking of the opposition to nuclear power and those who instead consider power plants to be uneconomical and opposed to the energy transition.
In Slovenia, this contrast is less pronounced, thanks in particular to the energy guaranteed by the Krško power plant.
In 2021, presenting the project that the government plans to lead to the construction of the new reactor, Slovenian Infrastructure Minister Jernej Vrtovec stated that Slovenia’s energy needs will grow in the coming years and that the country will depend on renewable sources In any case, points out “that they are still insufficient, so we need additional and stable alternatives”. According to the ministry, Slovenia will be able to reach the zero emissions target by 2050 thanks to the energy guaranteed by the new reactor.
Concerns about the safety of the power plant also appear to be marginal in Slovenia. Plant engineers contacted by ANSA said the plant is “located in an area with an expected seismic intensity of eight on the EMS scale, but is designed and built to operate safely even in the event of earthquakes of much higher intensity.”
In October 2021, the plant underwent an inspection by OSART, the Operational Safety Review Team of the IAEA, the International Atomic Energy Agency. Between October 4th and 14th, ten technicians from Belgium, Hungary, Pakistan, Spain, Switzerland, the United Kingdom and three members of the IAEA examined the safety plans and the organization of the plant. OSART has certified that the operational management can be considered correct and complete, without critical problems and with adequate security measures.