Half way - a review of post Fukushima actions in Europe

Fourteen European countries with operating nuclear reactors, and two others, participated in collaborative 'stress tests' starting in 2011; this began with operator reports, which were reviewed by national regulators, who wrote their own reports that were peer-reviewed, a process produced even more reports about a year ago. Later, there were visits. Since then, the industry has been in the follow-up stage, in which actions that have been promised are actually being carried out.

The organisation in charge, the European Nuclear Safety Regulators Group (ENSREG), published an action plan in August 2012 that laid out the next steps: countries' action plans to be published by the end of 2012, and peer-reviewed in a 22-26 April 2013 meeting. The results of this meeting are expected to be published this month at the second ENSREG conference on nuclear safety in Europe in Brussels (11-12 June). As of press date in early May, there is little information about what happened at that meeting except a short note from ENSREG's Helmut Klonk, chairperson of ENSREG Working Group on Nuclear Safety. He reported that 79 people took part, that participating countries and their regulators are committed to the process, and that emergent themes included the importance of the periodic safety review process and maintaining containment integrity under severe accident conditions.

ENSREG's August 2012 action plan also said that part of the awkward issue of international emergency response, mutual assistance amongst regulatory bodies during an accident in a member state, would be taken up by the Western European Nuclear Regulators Association (WENRA). It also recommended that the European Commission identify issues involved at a European level in implementing off-site emergency preparedness; it noted that the EC has commissioned a study to review off-site preparedness arrangements in EU member states.

In autumn 2012, a handful of units were singled out for a fact-finding follow-up site visit to prepare for the national action plans and subsequent peer review meeting. They include visits to Temelín (Czech Rep), Gundremmingen (Germany), Trillo (Spain), Chooz, Cattenom and Fessenheim (France), Ringhals (Sweden) and Sizewell B (GB).

A Greenpeace report published in April 2013 ('Critical Review of the National Action Plans (NAcP) of the EU Stress Tests on Nuclear Power Plants') criticised individual sites' post-Fukushima plans. It was not systematic but selected 13 of the 145 European nuclear power plants (the reasons for doing so were not made clear). They include all of the plants selected for the fact-finding trip except Trillo, Chooz and Sizewell B, as well as eight others. Most of the study's results are plant-specific, and so hard to generalise. But in its conclusion, it said that utilities' responses to stress test analyses fell into three general types: quick actions with no guarantee of the sufficiency of measures (for example, Wylfa of UK), comprehensive evaluations of hazards that will take more than a decade (for example, Cattenom of France), and actions that avoid major hardware improvements (Temelín of Czech Republic). Naturally it objects to all three, and argues that permanent shutdown should be considered, and is the only safe option in several cases. The report also criticises the reliance of mobile equipment for safety, calling it 'the new magic solution for severe deficiencies'. It says that the new equipment, although relatively inexpensive and easy to plan for, is worthless without training, and its efficacy relies on 'perfect intervention.' Furthermore, the report opposes backfitting because it is principally used in older plants, which are exposed to unspecified ageing-related effects. Finally, it opposes comprehensive plant modifications, since they would be used as a bargaining tool by utilities in exchange for operating licence extensions.

Above is a summary of the national action plans that were for the most part published in December 2012. With more than 1100 actions compiled, there were too many to list individually, so a statistical approach has been taken. The country-by-country boxes show the split of actions by type, and actions' average deadlines. For simplicity's sake, completed actions have been omitted, as have actions for national organisations and international cooperation. Although Switzerland participated fully in this process, it has been omitted from these tables because its national action plan was not initially published in English (see separate summary).

Although the format of the reports were similar, the detail of reported actions was surprisingly diverse. France, Europe's the largest nuclear country by far, had one of the shortest lists of actions. The longest was Belgium, with only seven operational reactors, but that like fellow long-reporters Germany and UK itemised actions by unit (not all did). We have taken this reporting variation into account in the way we compile summary statistics. Above we also list countries' deadlines for carrying out post-Fukushima studies and actions, expressed in months since Fukushima (this month is the 27th since then). This data should be treated with caution; some country reports' deadlines refer to completion of studies, others' deadlines were for completion of actions.

In general, actions such as acquiring mobile devices (diesel generators and pumps; fire trucks, and so on) and installing connections for pumps, have been completed or are in advanced stages in most countries. Hydrogen recombiners have been installed in some European countries, but are still several years off in others. The installation of filtered containment vents also appears to be a more long-term action, with studies still ongoing in many countries (UK, Spain, and elsewhere). Romania is one country that has a plan and schedule for installation of FCVs.

Like Ukraine, Switzerland participated every stage of the European stress test process, despite not being a member of the European Union. Unlike Ukraine, it drew up the results of its country peer review in a separate document, a Fukushima Action Plan. An English-language version of this document was published too late (mid-May) to include in our summary. Still, some general conclusions can be drawn. First, its regulator aims to have all post-Fukushima actions completed by 2017. Among tasks to be carried out include installation of spent fuel pool instrumentation, installation of a seal system at Beznau to prevent the migration of hydrogen around the plant. Also planned is the implementation of a diversified heat sink for Muehleberg; it currently relies only on the Aare river. A system to be implemented by 2017 will use a protected well fed by the Saane River for cooling.

Station blackouts could be very serious in Russian nuclear power plants, according to the translated executive summary of the Russian Federation's internal 'stress test' evaluation of nuclear power plants (from 2011): "At Russia's operating NPPs heat removal from the reactor cores (as well as spent fuel pools) cannot be carried out for an unlimited period of time in conditions of a full loss of the plant's in-house power. The latter is understood as a failure of power supply from the normal operation power sources, in particular, from the mains with overlapping failure of backup power sources, that is, diesel generators. As a result, by March 2012, 66 mobile diesel gensets (half of which were 2 MW), 35 mobile pumps and 80 engine-driven pumps had been supplied to Russia's 10 nuclear power plant sites. Post-Fukushima seismic and flooding reviews appeared to have found little of concern: VVER-1000s have a seismic margin; floods aren't a risk for most plants, but where they could be, the risk will be mitigated with mobile systems. Most of the country's short-term actions comprised those equipment orders, plus reviews of emergency procedures, increased beyond-design basis emergency drills, and the sourcing of standby service water sources.

Medium-term actions were to be carried out in the 2012-4 time period. VVERs will get pressure relief valves, and all NPPs will get hydrogen explosion prevention systems (PARs). An analysis of the failure of hydro dams near Balakovo and Novovoronezh will be carried out. A TETRA-based wireless radio system will be rolled out to all NPPs and the Rosatom crisis centre after being commissioned at Kalinin; construction of a spent fuel dismantling and storage facility is underway at Kursk and Smolensk, and was commissioned at Leningrad.

Long-term measures will not be completed until 2021. Emergency procedures and manuals are being rewritten; level 2 PSAs will be performed to develop severe accident management strategies. Other projects include design changes to plants under construction, both in terms of post-Fukushima stress tests (Beloyarsk 4 revision decisions approved; Novovoronezh 2, Leningrad 2 and Baltic revision being implemented, Rostov 3&4 under development), and in improving resistance to external effects (changes to mitigation of BDBA consequences approved for Rostov 3&4, Novovoronezh 2 and Leningrad 2). Also included is improving seismic stability of spent fuel pools.

Russian nuclear safety regulations are also changing to reflect post-Fukushima adaptations. An emergency power system needs to be included in a nuclear power plant to ensure safety when offsite power is lost. Plants need to install special engineered features to keep major safety functions operational in case of blackout, or loss of ultimate heat sink. Under certain (unspecified) accident conditions, containment can be vented for its own protection. Equipment will need to be installed to make sure that systems are monitored even in beyond-design basis events.

Also, Russia is setting up a regional crisis centre modelled after the Rosatom crisis centre for countries with VVER-type reactors (Russia, Czech Republic, Finland, Hungary, Slovakia, Ukraine, China), and improving worker medical/psychological screening.

WENRA's conclusions from the TEPCO Fukushima accident

A March 2013 study, 'Safety of new NPP designs', by the Reactor Harmonization Working Group of the Western European Nuclear Regulators Association, aimed to take common positions on selected key safety issues for the design of new nuclear power plants. It was based on earlier work on safety in operating and new nuclear power plants. Since a major part of the work was carried out before Fukushima Daiichi, a chapter deals with Fukushima-related safety issues. It said:

"A severe accident involving several units took place in Japan at Fukushima Daiichi nuclear power plant in March 2011. Even though in-depth analysis of this accident has not yet been completed, some items could be highlighted. The immediate cause of the accident was an earthquake followed by a tsunami coupled with inadequate provisions for tsunamis in the original design. Opportunities to improve protection against a tsunami were not adequately taken, which could have been possible for example as part of the PSR process...

"Safety culture and organisational factors, including decision making capabilities, contributed to the inadequate protection of the plants and to the difficulties in accident management...As a consequence of the tsunami, essential safety functions were lost at the plant, leading to core damage in three units and subsequently to considerable radioactive releases...

"The Fukushima Daiichi accident demonstrates the importance of properly implementing the defence-in-depth principle to ensure safety, getting the design basis for external hazards right, providing adequate protection against external hazards and the need to ensuring strong PSR process together with independent regulatory body to drive it. The accident also confirmed the need to have comprehensive safety analysis using both deterministic and probabilistic methods in a complementary manner to provide as full coverage of all safety factors as possible. In the safety assessment specific considerations are needed for multi-unit sites and to address long-term aspects...

"An important lesson from the accident was the importance of a control room and emergency response centre adequately protected against external hazards. Another key lesson was the need to attend to cooling and integrity of spent fuel pools as well as for the reactors. Siting has design implications, in particular in terms of securing sufficient diverse electrical and cooling supplies...

"In general, one has to bear in mind that the specific nature of individual events and challenges can never be completely taken into account in design and operation of a nuclear power plant (or indeed any other industrial facility)".