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IAEA Concludes Long Term Operational Safety Review of Slovenia’s Krško Nuclear Power Plant

Krško , Slovenia

An International Atomic Energy Agency (IAEA) team of experts has completed a review of long term operational safety at the Krško Nuclear Power Plant (NPP) in Slovenia.

The Pre-SALTO (Safety Aspects of Long Term Operation) review mission was requested by the plant’s operator, Nuklearna Elektrarna Krško (NEK). SALTO teams review the safe long term operation of NPPs based on IAEA safety standards.

Construction on the Krško NPP began in 1975 and it was first connected to the grid in 1981. It is Slovenia’s only nuclear reactor and co-owned by neighbouring Croatia.  Located in eastern Slovenia, Krško is equipped with one pressurized-water reactor and has a net electrical output of 696 MW(e). The operator plans to extend Krško’s operations until 2043. Pre-SALTO missions take place in advance of a plant entering the Long Term Operation (LTO) period. Krško will enter the LTO period in 2023.

During the 4-14 October mission, the SALTO team reviewed the plant’s preparedness, organization and programmes for safe LTO.

The review team found staff at the plant to be professional, open and receptive to suggestions for improvement.

“We observed that the operator is implementing preparations for safe LTO in a timely manner,” said team leader and IAEA Nuclear Safety Officer Martin Marchena. “A number of ageing management and LTO activities already meet IAEA safety standards. The SALTO team encourages the plant to address the review findings and progress with the implementation of all remaining activities for safe LTO.”

“We appreciate the IAEA's support to our plant in ageing management and preparation for safe LTO,” said Stane Rožman, President of the Krško Management Board. “The results of this mission will help us to improve our activities for safe LTO and to further align them with IAEA safety standards.”

The ten person team - comprising experts from Belgium, Hungary, Pakistan, Spain, Switzerland, the United Kingdom and three IAEA staff members - identified good practices and good performances that will be shared with the nuclear industry globally, including:

  • The plant has a well-structured and comprehensive programme of proactive and reactive activities for the ageing management of the safety related cables.
  • The plant has set up an efficient intranet portal which offers all staff access to relevant management applications, programmes, documents, procedures, data and records. 
  • The plant’s Steam Generator Ageing Management Programme demonstrates a strong commitment to excellence and several activities under this programme exceed international safety standards.

The team also provided recommendations to further enhance the preparations for LTO safety:

  • The plant should ensure detailed planning for the management of the third periodic safety review to begin in 2022 in support of LTO preparation.
  • The plant should complete the ageing management reviews of structures, systems and components.
  • The plant should implement effective knowledge management in support of LTO.

The plant management expressed a determination to address the areas identified for improvement.

The team provided a draft report to the plant management and to the Slovenian Nuclear Safety Administration (SNSA), the country’s nuclear regulatory authority, at the end of the mission. The plant management and SNSA will have an opportunity to make factual comments on the draft. A final report will be submitted to the plant management, SNSA and the Slovenian Government within three months.


General information about SALTO missions can be found on the IAEA website. A SALTO peer review is a comprehensive safety review addressing strategy and key elements for the safe LTO of nuclear power plants. They complement OSART missions, which are designed as a review of programmes and activities essential to operational safety. Neither SALTO nor OSART reviews are regulatory inspections, nor are they design reviews or substitutes for an exhaustive assessment of a plant's overall safety status.

LTO of nuclear power plants is defined as operation beyond an established time frame determined by the license term, the original plant design, relevant standards, or national regulations. As stated in IAEA safety standards, to maintain a plant’s fitness for service, consideration should be given to life limiting processes and features of systems, structures, and components, as well as to reasonably practicable safety upgrades to enhance the safety of the plant to a level approaching that of modern plants.

The IAEA Safety Standards provide a robust framework of fundamental principles, requirements, and guidance to ensure safety. They reflect an international consensus and serve as a global reference for protecting people and the environment from the harmful effects of ionizing radiation.

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