10 Years of Fukushima Part 5: Lessons Learned
The accident at the Fukushima Daiichi nuclear power plant caused the safety of nuclear power plants to be reviewed at national and international level and led to increased safety requirements worldwide.
Germany: "Stress test", Information Notice, and new regulations
German stress test. A few days already after the disaster at Fukushima, the Federal Ministry for the Environment commissioned the Reactor Safety Commission (RSK) to subject all German nuclear power plants to a safety review - also known as a "stress test". The aim of this review was to assess the robustness of the plants against impacts or events that go beyond the original design. Robustness in this context means the ability of a plant to remain in a safe condition even under such beyond-design conditions.
The operators of all German nuclear power plants had to present in a report what influence the listed scenarios had on the safety of their plants. The objective was to prove whether and to what extent the overriding protection goals – reactivity control, fuel cooling and limitation of the release of radioactive materials – could be met. The RSK evaluated the reports of the plant operators. The necessary inspections were organised by GRS on behalf of the RSK.
Information Notice. In the course of the stress tests, the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety commissioned GRS to prepare an Information Notice on the Fukushima accident. GRS always prepares such Information Notices when an event of safety significance occurs in a nuclear power plant in Germany or abroad. GRS investigates whether the event can be applied to other plants and, if necessary, derives appropriate recommendations.
National Action Plan. All European countries were required to draw up a National Action Plan after the accident at Fukushima. The Federal Ministry for the Environment published its national "Action Plan for the Implementation of Measures after the Reactor Accident at Fukushima" in December 2012. The plan had previously been coordinated with the nuclear authorities of all German Länder and the operators of the German nuclear power plants. In addition to the recommendations of the Reactor Safety Commission and the Information Notices of GRS, the action plan also took into account the results of the European stress tests and the recommendations of the International Atomic Energy Agency (IAEA).
National nuclear regulations. The findings from the analysis of the accident were also incorporated into the national nuclear regulations. As early as in 2012, various points were added to the Safety Requirements for Nuclear Power Plants, including the requirement for a diverse heat sink, increasing the capacity of the battery-supported DC power supply, more stringent requirements for accident monitoring systems, and extensive requirements for the control of natural and man-made hazards.
Europe: Stress test, EURATOM Directive and WENRA safety requirements
European stress test. In 2011, the then European Union Energy Commissioner Günther Öttinger ordered stress tests for all 143 nuclear power plants in Europe. The European Nuclear Safety Regulators Group (ENSREG) defined the scope of the tests. Similar to the national stress test of the Reactor Safety Commission, the countries had to present the safety of their nuclear power plants for various beyond-design-basis events. The results were published by the supervisory authorities of the Länder in the form of a report. The reports were subjected to a peer review by experts and specific recommendations were made. ENSREG published all essential recommendations and suggestions in its summary "Compilation of Recommendations and Suggestions from the Review of the European Stress Test".
WENRA Safety Reference Levels. In the same year, the Western European Nuclear Regulators Association (WENRA) – an independent network of European regulatory authorities – also revised its Safety Reference Levels for nuclear power plants on the basis of the new findings from Fukushima. Among other things, the requirement to consider natural hazards beyond the design limits was added. The requirements for preventive and mitigative measures and equipment for the control of beyond-design-basis accidents were also fundamentally revised.
International: IAEA Action Plan, CNS Special Conference, Vienna Declaration
Action Plan on Nuclear Safety. Internationally, too, the accident at Fukushima led to revisions of safety standards and a variety of follow-up measures for nuclear power plants. In 2011, the International Atomic Energy Agency (IAEA) drew up an action plan to improve the safety of nuclear power plants worldwide. The twelve overarching goals of the "IAEA Action Plan on Nuclear Safety" include e.g. the timely assessment of the protection of nuclear power plants against beyond-design-basis natural hazards, the improvement of emergency preparedness as well as ensuring independent and effective state supervision.
Vienna Declaration on Nuclear Safety. Almost four years after the events at Fukushima, the States Party to the Convention on Nuclear Safety adopted the Vienna Declaration on Nuclear Safety in 2015. By this joint declaration, the States Party commit to the following three principles of nuclear safety:
- New nuclear power plants must be planned and built in such a way that severe accidents are prevented. In the event of a severe accident with possible releases of radionuclides, there must be no long-term contamination outside the plant. Sufficient time must be available for protective measures of off-site emergency response.
- For existing nuclear power plants, safety must be regularly reviewed and improved.
- National regulatory frameworks should ensure these objectives and must take into account the Safety Standards of the IAEA and the Review Meetings of the Convention on Nuclear Safety (CNS).
Japan: New nuclear supervision and safety reviews
The Japanese government was initially occupied with investigating the sequence of events and the causes of the accident. Two government investigation commissions came to the conclusion that the catastrophe in its origin, course and severity was due to a large number of technical and organisational deficiencies. On the one hand, the Fukushima nuclear power plant was insufficiently resistant to beyond-design-basis events such as tsunamis. Secondly, there was a lack of appropriate accident management measures to stop any developing accidents or to limit their effects.
Find out more
>> Statement by the Reactor Safety Commission (RSK) (German only)
>> Information Notice of GRS (German only)