The spent nuclear fuel storage facility at the Krško nuclear power plant in Slovenia has just been commissioned with the placement of the first Holtec HI-STORM FW cask in the facility.
The dry storage building is one hundred and sixty feet by two hundred and thirty feet by sixty-six feet. It has a reinforced concrete base that is six feet thick. The plant is operated by Nuklearna Elektrarna Krško (NEK). They explained that the base and “the perimeter walls, provide protection against flooding and enable the anchoring of storage containers”. Equipment has been installed that allows monitoring by the International Atomic Energy Agency.
Each HI-STORM cask will hold thirty-seven spent fuel assemblies. A thick concrete shell provides full physical and radiological protection against extreme weather, earthquakes or an airplane crash. The containers have been designed to “enable the transport of the fuel elements in the future as part of a permanent solution”. In the first spent nuclear fuel loading project, sixteen HI-STORM FW casks holding a total of five hundred and ninety-two spent fuel assemblies will be placed in dry storage by late 2023.
Holtec was awarded a contract by NEK in February 2017. The contract included the design and construction of a dry storage building, replacement of the fuel handling building crane trolly, and supply of equipment and services.
Holtec stated that to ensure a large margin of structural safety, a seismically restrained version of the HI-STORM FW system was utilized for the Krško project. The seismic restraint system uses a robust steel structure embedded within the thick concrete foundation platform of the storage building. The HI-STORM FW casks are certified to withstand a severe earthquake that produces foundation pad accelerations two times greater than the Earth’s gravity. Holtec said that “The custom-engineered domed lid of the HI-STORM FW, unique to this project, is a Holtec innovation developed to engineer an impact-capable design.”
Rick Springman is the Holtec Senior Vice President of International Projects. He said, “Our success is a testament to the teamwork and ingenuity of the trans-national project team that executed the project. Commissioning of this facility was indispensable to support Krško's continued generation of 24/7 clean nuclear power, which is critical to Slovenia's clean energy aspirations”.
The seven hundred megawatt Krško plant is a Westinghouse pressurized water reactor. It was the first western nuclear power plant constructed in eastern Europe. Construction of the Krško plant began in 1975 and it was connected to the Slovenian grid in 1981. It began commercial operation in 1983.
In January of this year, the Slovenia's Ministry of the Environment approved Krško's operations for a further 20 years. The approval followed the completion of an environmental impact assessment. The assessment included input from neighboring countries Croatia, Austria, Italy and Hungary, plus Germany.
NEK said, “With the introduction of dry storage, we will fulfill all the conditions and implement the decisions of the administrative bodies to extend the operation of the nuclear power plant and provide customers with electricity at a reasonable price for another two decades.”