On 9 February 2015, a Diplomatic Conference of the Convention on Nuclear Safety (CNS) was held in Vienna. The decision to convene the Diplomatic Conference was taken in April 2014 at the Sixth Review Meeting of the Contracting Parties to the Convention on Nuclear Safety in response to a proposal by Switzerland to amend the Convention in light of the lessons learned from Fukushima.


The main outcome of the Diplomatic Conference was the adoption of the Vienna Declaration on Nuclear Safety by the Contracting Parties to the Convention on Nuclear Safety. The Declaration includes a political commitment by the Contracting Parties:

  • New nuclear power plants are to be designed and constructed with the objective of preventing accidents. In the event of an accident, no long-term external protective measures should become necessary.
  • Existing nuclear power plants should as far as possible be brought into line with the technical criteria and standards applicable to new nuclear power plants.

The Vienna Declaration requires Contracting Parties to report at the various review meetings on the implementation of the technical criteria and standards in their national regulations.

Although it was not possible to reach consensus on the inclusion of regulations in the Convention text itself, the international community’s adoption of the Vienna Declaration was a further milestone in improving nuclear power plant safety in the wake of the Fukushima reactor disaster. The Vienna Declaration supports dynamic development of safety standards in the direction already taken by Germany. If the Declaration’s objectives are to be met, upgrading of nuclear power plants may now become necessary in numerous countries. Whether and to what extent this is actually carried out, however, is a matter for each country to decide for itself.

Global validity

The united front presented by the member states of the European Union at the Conference made possible the Vienna Declaration’s incorporation of the safety objectives already adopted for the European Union in Council Directive 2009/71/Euratom establishing a Community framework for the nuclear safety of nuclear installations, as amended by Council Directive 2014/87/Euratom, thereby securing their global validity in the context of the Convention on Nuclear Safety.