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A.1. Design safety assessment of operating facilities against extreme hazards

The IAEA from June 2013 to December 2016 conducted a project to develop an internationally harmonised methodology for evaluating safety of NPPs against extreme hazards. The project resulted in the publication of an IAEA Technical Document (TECDOC 1834) titled Assessment of Vulnerabilities of Operating Nuclear Power Plants to Extreme External Events.

The 2011 accident at the Fukushima Daiichi nuclear power plant in Japan demonstrated the need to consider scenarios in which external hazards exceed a nuclear installation’s design basis events. Knowledge of plant behaviour during extreme event scenarios contributes  to plant safety as it enables  vulnerabilities to be identified and the introduction of measures to limit the progression of potential accidents. In November 2011, the IAEA released a methodology for the assessment of vulnerabilities of existing nuclear power plants to extreme natural hazards, as part of its work under the Action Plan on Nuclear Safety.

To meet Member States’ needs, the IAEA in June 2013 began revising the methodology enable it to cover a wider range of external hazards and to introduce enhancements.

The Technical Document includes guidance to a team that performs an independent review of the vulnerability assessment and a self-assessment questionnaire to support the application of methodology.

Two consultancy meetings and one Technical Meeting were held as part of the project. External experts contributed with independent reviews and providing comments during the meetings.


The project included the following activities:

  • Revision of the 2011 methodology document for systematic assessment of the impact of site specific external events on the NPPs and the evaluation of their safety margin in response to the imposed hazard;
  •  Preparation of guidelines for peer reviews;
  • Effective project management, technical expertise and implementation

Beneficiary Country: All Member States

The project was conducted by the IAEA with supplementary funding from the European Union.

Project Events

1st Consultancy Meeting

A Consultancy Meeting to discuss the draft TECDOC on "Assessment of Vulnerabilities of Operating Nuclear Power Plants to Extreme External Events under Project A1 was held in Vienna 28-30 January 2015.

2nd Consultancy Meeting

A consultancy meeting to discuss the complete draft TECDOC on "Assessment of Vulnerabilities of Operating Nuclear Power Plants to Extreme External Events" under Project A1 was held in Vienna 9-10 June 2015.

Technical Meeting

An IAEA Technical Meeting to present and review the complete draft Tec Doc developed under A1 was held in Vienna 23–27 November 2015.

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