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Safety: Extreme risks - A better protection of nuclear installations. An ultimate-emergency Diesel - Expertises reported during their design. Major accident - Efficiency of the ultimate cooling. Tricastin power plant - After expertise, the dyke is strengthened. Research - Innovative materials. Crisis and post-accident - The definition of new zonings. The protection of the population - Which advances in ten years? Environmental contamination - Models in progress. 2011-2021: the actions of the IRSN
[en] This file addresses various aspects and measures regarding the safety of nuclear plants and installations which have notably been developed and implemented after the return on experience of the Fukushima accident. It addresses the improvement of the protection of nuclear installations, notably with the concept of 'hard core' and its associated elements (ultimate emergency Diesel, local crisis centre, ultimate water source), and focuses on the ultimate emergency Diesel by evoking expertise reports of assessment of its design. It addresses the efficiency of the ultimate cooling with the study of the heat evacuation system (the efficiency is being studied and recommendations for additional actions have been stated by the IRSN), and the improvement of the invert strength. The case of the Tricastin nuclear plant is addressed with the strengthening of the dyke which has been decided after the expertise which followed the Fukushima accident. An article proposes an overview of research activities on innovative materials to limit radioactive releases (the Mire project), or to recover fuel debris in order to prepare dismantling in Japan (the Preades project). Organisational aspects are also addressed for the crisis and post-accidental management with notably the definition of new zoning areas, the optimization of models, the organization of closer and quicker measurements, the definition of specific intervention plans, means to be deployed for the mapping of a contaminated territory. An article proposes an overview of advances in population protection during the last ten years (preventive iodine ingestion, health control, radiation protection measures). The issue of environmental contamination is finally addressed: advanced models based on researches on long term effects through the study of the transfer of radionuclides into ecosystems, the model uncertainty assessment. The last article proposes an overview of actions undertaken by the IRSN in Japan since 2011
[en] The alert came just before sunrise in Vienna on 11 March 2011. The on-call emergency response manager reviewed the seismic report that opened on his laptop screen. Within minutes, staff trained in specialized response roles were called into the IAEA’s Incident and Emergency Centre (IEC). He had initiated the IEC’s ‘full response’ for the Fukushima Daiichi nuclear accident, based on the results of an assessment that followed pre-established procedures. ‘Full response’ means that over 200 staff members trained in regular exercises operate in 12-hour shifts, 24 hours per day, gathering information from emergency contact points in the ‘Accident State’ — in this case, Japan — and other Member States, dispatching IAEA assistance when requested, informing the international community, while updating the media and public and coordinating the international response.
[en] Less than an hour. That’s the time it took the earthquake-triggered tsunami of 2011 to reach Japan’s eastern shoreline. Soon after, the first tsunami hit the Fukushima Daiichi nuclear power plant, leading to an accident that forced tens of thousands of people to evacuate. Since then, the Government of Japan and the authorities of Fukushima Prefecture have made significant efforts to make much of the evacuated areas inhabitable again. A decade after the accident, what does life look like in the affected areas of Fukushima Prefecture? The IAEA has provided technical expertise, equipment, expert missions and guidance on recovery operations — based on international examples and the IAEA safety standards. It has been supporting Japanese authorities and scientists in three technical areas: radiation monitoring, remediation and the management of waste from decontamination activities.
[en] Why is leadership vital in nuclear safety? Leadership is needed to initiate appropriate safety actions, motivate staff to ensure safety procedures are followed 24/7, and provide guidance on implementing safety measures. Learning about the importance of leaders in safety is part of the IAEA International School of Nuclear and Radiological Leadership for Safety, launched in 2016. Cultivating a safety culture among staff, so that they can understand the importance of safety and the measures required to sustain it, is key in the nuclear industry. Establishing a strong safety culture is one the most fundamental management principles when using nuclear technology. It aims to strengthen the implementation of a systemic approach to safety, that is, the interaction between humans, technology and organizations within the national nuclear infrastructure. The importance of safety culture is one of the key lessons learned from the Fukushima Daiichi nuclear accident.
[en] HANARO has been actively utilized since attaining first criticality in 1995. In 2009, the cold neutron source was installed inside the reflector tank. The main utilization fields of HANARO are neutron beam applications, nuclear fuel and material test, radioisotope production, neutron activation analysis and neutron transmutation doping. After the Fukushima accident, HANARO had been requested to evaluate the seismic margin for the reactor’s main components, and the seismic margin assessment led to the reinforcement of HANARO’s wall. In December 2017, HANARO started operating after overcoming many issues for about a 3 year-shutdown. For the period of long-term shutdown, the circumstances surrounding HANARO, such as research reactor regulation and new research reactor construction project, has been drastically changed. To meet the expectations of HANARO to produce world-class science and to respond to the rapidly changing environment, a strategic plan for HANARO was prepared, and 4 missions were re-established. They are 1) advancement of neutron science and technology, 2) not only meeting but also creating the needs of the industry, 3) contributions to the national society issues, and 4) safe and stable operation of the facility. To achieve the missions, all members involved in the HANARO shared their same perception that the stable operation of HANARO is the most important. HANARO is trying hard to give the confidence for its sustainability and excellence through the various activities. (author)
[en] Full text: After the accident of Fukushima Dai-ichi Nuclear Power Station occurred, reconstruction as well as reaffirmation of nuclear safety systems have been conducted in the world. Before the accident, severe accident management (SAM) had not been prepared enough in Japan. It was obvious that the luck of consciousness of SAM caused the accident. Thereafter, raising the level of SAM was top priority task and a lot of programs on SAM strengthening were introduced into every nuclear facility in Japan. As catching up in the SAM level of advanced countries having nuclear power plants in the world, the importance of comprehensive safety measure has been reconfirmed from the viewpoints of plant life cycle management, e.g. safe long term operation as well as accident management, e.g. defense depth. It is difficult to raise the comprehensive safety level immediately, a roadmap especially focusing on the safety research issues of Light-Water Reactor (LWR) has been developed by a lot of stakeholders, that is experts of government, academia and industry in the committee of Atomic Energy Society of Japan; AESJ since 2014. The roadmap covers seven categories, such as “1) Risk Management”, “2) Design”, “3) Operation and Maintenance”, “4) Accident Management”, “5) Decommissioning”, “6) Nuclear Security” and “7) Innovation Technique”. Every category issue is considered with safety measures as well as human resource developments. In order to avoid dropping off issues which belong to multiple categories, cross cutting issues are deeply focused. For example, utilization of the latest knowledge about safety operation and decommissioning for next generation plant designs should be covered in the roadmap as a cross cutting issue. That is one of the important viewpoints of “Plant Life Cycle Management”. This presentation explains the outline of the comprehensive LWR safety research roadmap covering technical as well as social issues developed in Japan. (author)
[en] This white paper aims at proposing answers to some questions regarding the situation in Fukushima and the consequences of the accident, notably the situation regarding dismantling, the remaining radioactive substances, lessons learned, and other issues. Thus, a first article presents the radio-ecology discipline and describes how this technique allowed the control and reduction of radionuclide transfers in Fukushima (interview of an IRSN expert). A second article addresses the transport of radioactive substances, more particularly in France where nearly hundred significant events are noticed every year. Classification (in terms of hazard) and regulation (technical requirements and others related to radioactive products and to their transport) aspects are overviewed. The third article addresses the evolution of the dismantling of the Fukushima Daiichi nuclear plant (interview of an IRSN expert). The last article discusses the action plan implemented by France to improve the safety of its nuclear installations, with the installation of back-up Diesel units, the installation of ultimate water sources to cool reactors, and the construction of local crisis centres able to withstand extreme aggressions. Five articles are also proposed. They address the French challenge of management of nuclear wastes, the development of small nuclear reactors everywhere in the world, the necessary adaptation of nuclear plants to extreme air temperatures, the safety of French nuclear installations which is globally good but still to be improved, and the causes and consequences of the Fukushima accident.
[en] On 11 March 2011, the Great Japanese Earthquake shook the Asian seabed so powerfully that it moved the main island of Japan two and a half metres to the east. As the ensuing tsunami swept across the mainland, it breached Japan’s coastal defences including the perimeter of the Fukushima Daiichi’s Nuclear Power Plant, causing the release of radionuclides. Even so, scientists have found no evidence that this radiation caused health-related effects. The accident prompted a concerted and coordinated response by the international community, which has led to a significant improvement in the safety and safety culture in the nuclear sector. Three months after the accident, the IAEA hosted a Ministerial Conference on Nuclear Safety and the IAEA Action Plan on Nuclear Safety was endorsed in September 2011. Nuclear engineers worldwide poured over their reactors analysing and upgrading equipment. They shared their knowledge and findings and four years later, the IAEA published its comprehensive report on the accident. It is important to recognize the progress made in nuclear safety in Japan and worldwide in the past decade. Nuclear is safer than it has ever been. Nonetheless, we cannot be complacent. I continue to emphasize the need to remain vigilant and put safety first. The 7.3-magnitude earthquake that hit Fukushima in 2021 is a reminder of the need to keep our safety focus. The stakes are even higher today, because we need nuclear power to expand if we are to avoid the worst consequences of climate change.
[en] The Fukushima Daiichi nuclear accident reinforced the importance of having adequate national and international safety standards and guidelines in place so that nuclear power and technology remain safe and continue to provide reliable low carbon energy globally. By recognizing the lessons learned from the 2011 accident, the IAEA has been revising its global safety standards to ensure that Member States continue to receive up-to-date guidance of high quality.
[en] Katsushika Ward, located in northeastern Tokyo, had the highest deposition in Tokyo of artificial radionuclides after the Fukushima Daiichi Nuclear Power Plant accident. A car-borne survey for measuring absorbed dose rate in air was carried out in the ward in each of the years 2015-2020. The average dose rates measured in 2015-2018 decreased every year but percentage reductions were smaller after 2018 due to the decrease in 134Cs amount; this radionuclide decays with a half-life of 2.065 years. Its ecological half-life was estimated to be 1.6 y and that value was shorter than the physical decay life (3.2 y). (author)