On 11 March 2011, Japan was struck by a severe earthquake. This earthquake and the tsunami which followed caused serious damage to several Japanese nuclear power plants, in particular the Fukushima Daiichi plant. On the same day, a crisis unit was set up by the German Environment Ministry; this unit continued to exist, expanding as necessary, for more than four weeks. Its primary aims were to keep the German public informed about events in Japan and their impact, to prevent the importation of potentially contaminated foodstuffs and products and to ensure that German citizens in Japan at that time were protected from any radiological effects arising from the accident. This also involved dispatching representatives of the Federal Environment Ministry to the German embassy in Tokyo.
On 14 March 2011, in light of events in Japan, the federal government and the Minister-Presidents of the five Länder (German federal states) with nuclear power plant sites decided to review the safety of all German nuclear power plants. The independent Reactor Safety Commission (RSK), responsible for advising the Federal Environment Ministry on nuclear safety issues and staffed by a panel of renowned experts, was commissioned with the assignment and final evaluation of the safety review of all German nuclear power plants as a robustness test. In summary, the RSK observed in its first statement dated 16 May 2011 that German facilities appear to be better prepared than the Fukushima power plant with regard to electricity supply and protection against flooding. Further robustness tests revealed no uniform findings that could be related to either plant design or age. The RSK concluded its extensive deliberations on relevant insights from the Fukushima accident for German nuclear power plants with its recommendation of 26 and 27 September 2012.
Concurrent with the work of the RSK, the federal government convened the Ethics Commission for a Safe Energy Supply at the beginning of April 2011 with the aim of establishing a public consensus on future energy supply and discussing the risks of using nuclear energy. The Ethics Commission submitted its recommendations on 30 May 2011, concluding that although the risks associated with nuclear energy may not have changed owing to the events in Fukushima, the way these risks were perceived had. The possibility of an accident spiralling out of control is of crucial importance at the national level. The commission recommended limiting the use of nuclear energy for commercial electricity generation as far as possible and phasing-out nuclear energy within a decade. It also stated that a phase-out would be possible due to the existence of lower-risk alternatives.
On the basis of the findings of reviews, discussions and reports submitted by both the RSK and the Ethics Commission, the '13th Act amending the Atomic Energy Act’ was adopted by a large majority in the German Parliament on 30 June 2011 and entered into force on 6 August 2011. The operating licenses of the seven oldest nuclear power plants and the Krümmel nuclear power plant expired with the entry into force of the act. Owing to a prior decision of the federal government and the Minister-Presidents of the Länder with nuclear sites, these nuclear power plants had already been taken off the grid. The remaining blocks were subsequently shut down (2015 Grafenrheinfeld, 2017 Grundremmingen B, 2019 Philippsburg 2) or will be permanently shut down in a phased approach by the end of 2022 (2021 Grohnde, Gundremmingen C, Brokdorf, 2022 Isar 2, Emsland and Neckarwestheim 2).
At European level, the European Council of 24 and 25 March 2011 declared that "the safety of all EU nuclear plants should be reviewed, on the basis of a comprehensive and transparent risk and safety assessment (stress tests)". In Germany, in addition to the RSK's own safety reviews, the EU stress test was conducted during the second half of 2011. The test revealed that in terms of the three central aspects (external events, power and coolant failure, accident management measures) conservative and robust design requirements had been realised at the time of construction. There remained, however, room for ongoing improvements to power plant safety.
Based on the concepts drawn up by the operators of the German nuclear power plants, the RSK deliberated on the implementation of its recommendations in the plants and issued the RSK statement "Evaluation of the implementation of RSK recommendations in response to Fukushima" on 6 September 2017. The RSK concluded that robustness had improved compared to the RSK safety review of 2011 because of the measures that had been undertaken. The RSK determined that its recommendations had been largely implemented by the concept.
In response to the nuclear accident in the Japanese nuclear power plant Fukushima Daiichi, stress tests were carried out in all European member states with nuclear power plant sites as well as in Switzerland and Ukraine. The stress tests were followed by peer reviews within the framework of the European Nuclear Safety Regulations Group (ENSREG).
ENSREG subsequently adopted an action plan. In April 2013, the resulting national action plans were discussed for the first time among member states and it was recommended that the national supervisory authorities update the plans on a regular basis. The aim was for the participating states, while maintaining their national responsibility for nuclear safety, to agree on a widely harmonised level of risk reduction regarding extreme events in nuclear power plants. An updated action plan was published in 2017, which outlines the measures taken in Germany after the nuclear accident in Fukushima. It was drawn up by the Federal Environment Ministry, the nuclear supervisory authorities of the Länder, the Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) gGmbH and with the support of the operators of German nuclear power plants.
In addition to the safety review of German nuclear power plants, risk analyses were carried out for other nuclear facilities. The competent supervisory authorities of the Länder conducted the review of all research reactors with a continuous thermal load of over 50 kilowatts and forwarded the results to the RSK. The RSK prepared a statement entitled "Plant-specific safety review (RSK-SÜ) of German research reactors in the light of the events in Fukushima-1 (Japan)" dated 3 May 2012.
In summer 2011, the Nuclear Waste Management Commission (ESK), an additional advisory body to the Federal Environment Ministry comprising independent experts, was commissioned with developing evaluation approaches for stress tests for facilities in operation or under construction for the disposal of irradiated fuel elements and radioactive waste as well as for installations for uranium enrichment in Gronau and for fuel element manufacturing in Lingen. The ESK divided its statement into two parts on account of the large number and variety of facilities to be examined as well as the wide-ranging radioactive inventory to be accounted for in the stress test. The first part was published on 14 March 2013 and the second on 11 July 2013.
Following the analysis of the events in Fukushima, the Federal Environment Ministry implemented an additional important measure in June 2011. The Commission on Radiological Protection (SSK) was commissioned with a review of the statutory regulations governing off-site nuclear emergency response. The way the accident unfolded in Japan was very different from the accident in Chernobyl. That is why new experiences were gained in almost every field of emergency preparedness. The review of statutory regulations took into account the accident analysis conducted by the Japanese government and the International Atomic Energy Agency, the RSK safety review as well as the experiences and observations of the SSK emergency task force. In February 2015, the SSK published 76 recommendations on the further development of emergency response based on experience gained in Fukushima I (SSK recommendation for further development of emergency response due to the implementation of experiences made in Fukushima).