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IAEA Leads Operational Safety Mission to Kozloduy Nuclear Power Plant

Kozloduy, Bulgaria

An IAEA-led international team of nuclear safety experts noted a series of good practices and made recommendations to reinforce some safety measures during a review of safety practices at the Bulgaria's Kozloduy Nuclear Power Plant (NPP) that concluded today.

The Operational Safety Review Team (OSART) mission was undertaken at the Bulgarian Government's request. The in-depth review, which began 26 November 2012, focused on aspects essential to the safe operation of the NPP. The team was comprised of experts from Belgium, Canada, the Czech Republic, Finland, Germany, Hungary, Slovakia, Sweden, Ukraine, the United Kingdom and the IAEA.

The review covered the areas of management, organization and administration; training; operations; maintenance; technical support; operating experience; radiation protection; chemistry; and emergency planning and preparedness. The conclusions of the review are based on the IAEA's Safety Standards.

The OSART team identified good practices used at the Plant that will be shared by the IAEA with the nuclear industry world-wide. Examples include:

  • The Plant uses special procedures to reduce corrosion in the reactor's secondary cooling circuit;
  • The Plant has developed procedures for using additional redundant sources of electrical power supply that have been tested and validated during an emergency exercise; and
  • The Plant performs independent measurement of fuel assembly enrichment to verify that the fuel assemblies are manufactured in compliance with design specifications.

The team identified a number of proposals for improvements to operational safety at Kozloduy NPP. Examples include:

    • Written procedures for dose assessment from neutrons are not available at the Plant and neutron dose assessments are not performed for all relevant staff;
    • Severe accident management guidelines have not been created for situations that involve open reactor conditions or spent fuel ponds; and
    • Analyses of the cause of events are not always performed in a thorough and timely manner to prevent the recurrence of events related to human performance.

Plant management expressed a determination to address all the areas identified for improvement and requested the IAEA to schedule a follow-up mission in approximately 18 months.

The team handed over a draft of its recommendations, suggestions and good practices to the plant management in the form of "Technical Notes" for factual comments. The technical notes will be reviewed at IAEA headquarters, including any comments from Kozloduy NPP and the Bulgarian Nuclear Regulator. The final report will be submitted to the Bulgarian government within three months.

This was the 174th mission of the OSART programme, which began in 1982, and the third at Kozloduy.


An OSART mission is designed as a review of programmes and activities essential to operational safety. It is not a regulatory inspection, nor is it a design review or a substitute for an exhaustive assessment of the Plant's overall safety status. Experts participating in the IAEA's June 2010 International Conference on Operational Safety of Nuclear Power Plants (NPP) reviewed the experience of the OSART programme and concluded:

      • In OSART missions NPPs are assessed against IAEA Safety Standards which reflect the current international consensus on what constitutes a high level of safety; and
      • OSART recommendations and suggestions are of utmost importance for operational safety improvement of NPPs.

The IAEA Nuclear Safety Action Plan defines a programme of work to strengthen the nuclear safety framework worldwide in the light of the Fukushima Daiichi Nuclear Power Plant accident. The plan was unanimously endorsed by IAEA Member States during the Agency's 55th General Conference in September 2011. The Action Plan recommended: "Each Member State with Nuclear Power Pplants to voluntarily host at least one IAEA Operational Safety Review Team (OSART) mission during the coming three years, with the initial focus on older nuclear power plants. Thereafter, OSART missions to be voluntarily hosted on a regular basis."

General information about OSART missions can be found on the IAEA Website: OSART Missions.

Last update: 16 Feb 2018

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