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Following an accident, a strategic plan for maintaining long term stable conditions and for the decommissioning of accident damaged facilities is essential for on-site recovery. The plan needs to be flexible and readily adaptable to changing conditions and new information. |
Preparations for the decommissioning of a facility damaged in an accident would first involve stabilization to ensure that structures, systems and components are in place to reliably maintain stable conditions for the long term until their functions are no longer needed. Post-accident preparations for decommissioning take decades. Arrangements are necessary to maintain the necessary expertise and workforce throughout this entire period. Decision making on interim decommissioning stages and on the final conditions of the site and the damaged reactors needs to include a dialogue with stakeholders. Decision making on decommissioning depends on the conditions of the damaged reactors, fuel and debris, which cannot be determined in the period immediately following an accident. Factors to be considered in decision making include: dose levels for workers in decommissioning; the volumes and types of waste generated; and the efforts necessary for waste treatment. In the early stage of cleanup activities, it is unrealistic to predict the final conditions of the plant site, but expectations and plans for the land need to be considered in the decision making process. |
| Reference Document:
Director General’s Report on the Fukushima Daiichi Accident |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/Pub1710-ReportByTheDG-Web.pdf#page=175 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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Retrieving damaged fuel and characterizing and removing fuel debris require solutions that are specific to the accident, and special methods and tools may need to be developed. |
A reactor accident involving damage to nuclear fuel results in particular conditions in the reactor that are unique to the accident. The removal and management of damaged fuel elements and of debris from melted fuel are complex tasks. The debris needs to be characterized, removed, packaged and placed in storage until disposal is implemented, under difficult conditions, associated largely with high radiation levels. |
| Reference Document:
Director General’s Report on the Fukushima Daiichi Accident |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/Pub1710-ReportByTheDG-Web.pdf#page=175 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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National strategies and measures for post-accident recovery need to include the development of a generic strategy for managing contaminated liquid and solid material and radioactive waste, supported by generic safety assessments for discharge, storage and disposal. |
A waste management strategy is needed for the implementation of pre-disposal management (e.g. handling, treatment, conditioning and storage) of accident-generated contaminated material and radioactive waste. It also needs to identify appropriate routes for the disposal of materials. Waste management strategies may involve the use of existing processing, storage and disposal facilities, such as incinerators or leachate controlled landfills. However, other approaches may be necessary, depending on the volumes and characteristics of the waste involved. The development of such strategies could be supported by the development of a generic safety case. Strategies for the post-accident management of large volumes of contaminated water are also necessary, including consideration of its controlled discharge to the environment. Although there is international guidance for discharges during the normal operation of nuclear facilities, further guidance on its application in post-accident situations is needed. |
| Reference Document:
Director General’s Report on the Fukushima Daiichi Accident |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/Pub1710-ReportByTheDG-Web.pdf#page=176 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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It is necessary to recognize the socioeconomic consequences of any nuclear accident and of the subsequent protective actions, and to develop revitalization and reconstruction projects that address issues such as reconstruction of infrastructure, community revitalization and compensation. |
Nuclear accidents and the protective and remedial actions introduced in both the emergency phase and the post-accident recovery phase, with the objective of reducing doses, have far-reaching consequences on the way of life of the affected population. Engagement of stakeholders at various stages of remediation and recovery is essential. |
| Reference Document:
Director General’s Report on the Fukushima Daiichi Accident |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/Pub1710-ReportByTheDG-Web.pdf#page=176 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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Support by stakeholders is essential for all aspects of post-accident recovery. In particular, engagement of the affected population in the decision making processes is necessary for the success, acceptability and effectiveness of the recovery and for the revitalization of communities. An effective recovery programme requires the trust and the involvement of the affected population. Confidence in the implementation of recovery measures has to be built through processes of dialogue, the provision of consistent, clear and timely information, and support to the affected population. |
Governments need to provide a realistic description of a recovery programme to the public that is consistent, clear and timely. A variety of information channels, including social media, need to be used to reach all interested groups. Perceptions of radiation risks and answers to questions about ‘safe’ radiation levels have many dimensions, including scientific, societal and ethical. These answers need to be clearly communicated to relevant communities through educational programmes — ideally before an accident has occurred. It is important that the affected population receive support for local recovery efforts. Support for self-help actions related to remediation and for rebuilding businesses can increase involvement in the recovery programme, and build the trust of the affected population. |
| Reference Document:
Director General’s Report on the Fukushima Daiichi Accident |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/Pub1710-ReportByTheDG-Web.pdf#page=176 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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The safety of nuclear installations, in general, and the site related aspects, in particular, needs to be reassessed during their operational life in response to new knowledge, new hazards, new regulations and new practices, as part of periodic safety reviews. In this regard, the role of national and/or international independent peer reviews needs to be emphasized as an important tool to assess and enhance safety. |
The requirement for a reassessment process of site related aspects needs to be included in the regulatory framework, and the responsible organization needs to implement the plant safety improvements in a timely manner based on the results of this process. This needs to cover, in a systematic and comprehensive manner, all natural and human induced hazards which may create or exert potential effects on nuclear installation safety, as well as the impact on the environment. The reassessment process needs to be performed in accordance with periodic safety reviews and international safety standards and recognized engineering practice. In this regard, international peer review missions are key elements for assessing and enhancing safety with another layer of effective actions which may contribute to cope with the lack of timely actions or responses by the responsible organizations and/or the regulatory bodies. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=60 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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National and international standards to cope with external events in siting, site evaluation and design aspects need to be periodically updated and revised in accordance with scientific and technical developments, recognized engineering practices as well as using information from experience of recently occurred extreme natural external events. |
The experience and data obtained during the 11 March 2011 earthquake and tsunami in Japan will be useful in the revision of national regulations in the effort: (i) to bring them in line with modern criteria and methodologies; and (ii) to be able to cope better with the involved uncertainties in the assessment of these extreme natural hazards. Regulatory documents need to ensure that databases take into account pre-historical and historical events commensurate with the low annual frequency of occurrence of the extreme natural phenomena in line with the relevant IAEA safety standards. It has been demonstrated that one reason for the underestimation of the 11 March 2011 tsunami was that only Japanese historical data were taken into account in the evaluations as well as in the use of methodologies applied on the basis of an incorrect consensus approach. Since: (i) the magnitudes of all historical earthquakes were smaller than 9; (ii) the historical earthquake magnitudes and/or intensities were not increased as conservatively done in international deterministic practice; and (iii) none were located in the offshore region facing Fukushima, the earthquake and subsequent tsunami hazards were underestimated. Evaluations using standard practice underestimated the tsunami height that might occur, as happened in March 2011. At the same time, some experts and institutions using alternative approaches based on the source model proposed by HERP determined tsunami flood levels comparable to the 2011 ones in the Fukushima area. These discrepancies between different expert opinions need to be properly treated, since all of them might contribute to reducing the uncertainties that exist in assessing extreme natural events. Therefore, the use of mainly national historical data is not sufficient to characterize the risk of extreme natural hazards, as highlighted by IAEA safety standards since 2003. The prediction of extreme natural hazards often remains difficult and controversial. Natural hazards assessment, as well as reassessments, should be performed in a conservative way and be updated according to new knowledge, as soon as available. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=60 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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Assumptions of complex scenarios need to be made and adequate conservative estimations need to be applied at the site evaluation, design and different operational stages in relation to the potential occurrence of extreme external events of very low frequency but with high safety consequences. When operating nuclear installations are faced with revised estimates that exceed previous predictions, it is important to take interim corrective actions in a timely manner by the responsible organization and the regulatory authority. |
The consideration of uncertainties involved in the knowledge and determination of the loads on SSCs during the operational life of the installation requires the assumption of complex scenarios in a comprehensive manner from the beginning of the process. Correspondingly, an appropriate regulatory framework has to be in force and in line with the identified needs to be able to request, control, regulate and provide guidance on the acceptable level of risk and the performance criteria that the installation has to comply with to safely cope with assumptions of extreme external events during the operational life of the plant. In the case of the Fukushima Daiichi NPP, it has been demonstrated that interim corrective measures were not taken in a timely manner. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=61 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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The assessment of natural hazards needs to be sufficiently conservative. Particularly in relation to the assessment of tsunami hazards, there is a need to use highly conservative assumptions for estimating the tsunami heights (maximum and minimum), runup and other site associated phenomena. They should be based on pre-historical and historical specific data commensurate with the low annual frequency of their occurrence and, if such specific data are not fully available, using appropriate global analogues. |
The consideration of mainly historical data in the establishment of the design basis is not sufficient to characterize the risks of extreme natural hazards. Even when comprehensive data are available, due to the relatively short observation periods, large uncertainties remain in the prediction of natural hazards. Regarding the need to apply a more conservative approach for tsunami hazards than those used for other external natural hazards, the main reasons are as follows: • Large aleatory and epistemic uncertainties in parameters involved in tsunami hazard calculations, particularly in the characterization of the tsunamigenic sources; • Significant variations in inundation levels at different parts of the site considering the specific and detailed plant layout and the elevations of different plant sectors; • Difficulties in incorporating effective tsunami protection measures for operating plants after an increase in tsunami height estimation resulting from periodic reassessments; • Inability of SSCs at nuclear plants to cope with increased flood heights with respect to the design levels, with possible flood related cliff edge effects seriously affecting the safety of the nuclear installation. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=61 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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Regarding uncertainties in tsunami hazard calculations, special attention needs to be paid to the aleatory and epistemic uncertainties associated with the maximum magnitude earthquake related to tsunamigenic sources such as major subduction zones. |
In general, the assessments of the magnitude of historical tsunamigenic earthquakes contain large uncertainties because they are inferred from damage caused on land, sometimes at a distance of more than 100 km, as well as on tsunamis that also heavily depend on bathymetry and coastal topography. For these reasons, a higher degree of conservatism may be necessary in the estimation of maximum magnitudes for tsunamigenic seismic sources at the time of the original design in order to avoid onerous physical upgrades later on during the design, construction or operational stages, or when such hazards are reassessed. While the prevailing view among Japanese scientists before the earthquake of 11 March 2011 was that an M 9 earthquake could not be generated by the Japan Trench, as it has been for this Pacific tectonic plate in the past (in Chile and Alaska), it is important that diverse expert opinions from recognized scientific or academic institutions (both nationally and internationally) be considered to account for the epistemic uncertainties for assessing natural hazards. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=61 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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There is a need to use a systemic approach in dealing with the design and layout of SSCs for effective protection against flooding hazards. |
The dry site concept is considered to be a crucial element for coping successfully with flooding hazards, and it has to be formulated from the beginning of the NPP project. It needs to be periodically reassessed and maintained, and, if conditions for a dry site change, adequate protective measures need to be taken in a timely manner. The selection of the main plant grade level during the first stages of the NPP project is a critical aspect which needs to receive careful consideration due to its importance for the dry site concept. Leaktightness and water resistance also have to be ensured through a comprehensive evaluation of all potential waterways, although this measure can only be used as a redundancy, i.e. in conjunction with a dry site or an effective site protection measure. Thus, the main plant grade level has to be determined with sufficiently large safety margins to avoid flooding hazards due to cliff edge effects. On the other hand, for those plant design aspects which may be seriously affected by external flooding but for which major uncertainties or insufficient knowledge exist, larger conservatisms have to be applied with respect to other site related aspects and external events for which those issues are better controlled. The same is true for those aspects with more difficulties and complexities in executing effective upgrades, or with higher consequences in case of failure that may affect the defence in depth concept. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=62 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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There is a need to act effectively and promptly in implementing upgrading measures to maintain the defence in depth concept of an installation and to ensure the performance of safety functions when an original dry site becomes a wet site during its operational life as result of a reassessment of the flooding hazards at the site (i.e. having a potential for higher flood levels than the main plant grade level). |
Attention has to be paid to the fact that the upgrading measures to protect an operational installation that is now located on a wet site, and the closing of all possible waterways, may be practically more difficult to implement for an existing facility than for a new site, where such measures would form part of its original design and construction. In the case of indications of evidence of greater hazards than those originally predicted in the design bases, the responsible organizations have to react effectively and promptly, and ensure safety through the implementation of interim measures while final confirmation of such evidence is obtained. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=62 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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Complex scenarios involving consequential or independent occurrences of multiple external hazards affecting multiple units located on a site and, possibly, multiple NPPs at different sites in the same region need to be considered in accident scenarios and actions to be taken. |
Due to the nature of the Fukushima Daiichi accident, the lessons learned will cover a very wide area, which involves a wide variety of findings. Traditional engineering thinking for verifying the adequacy of a design involves characterizing limit states and comparing the effects of the loads on the installation (the demand) with the strength (the capacity) of the installation. However, the greatest uncertainties in this process are with the definition of the acting loads, i.e. with the demand imposed on the installation. For this reason, design loads are defined to cover credible, possible and likely situations. In this sense, the design loads need to cover the potential of the occurrence of extreme events in the future. They have to be properly and conservatively estimated by the designer. The designer, in the final design process, may or may not derive the proper design basis criteria with due account taken of complex scenarios of either extreme or severe natural hazards and with enough conservatism to comply with the defence in depth concept and to ensure adequate safety margins. The potential for complex scenarios involving multiple external hazards that affect multiple units at the same site and at the regional scale, and possibly multiple sites in the region, needs to be comprehensively considered in the accident scenarios and measures to be taken. If such scenarios cannot be screened out, provisions need to be made for plant layout, site protection measures, design of shared and non-shared SSCs, accident management and off-site emergency preparedness and response in order to protect the plants from natural disasters in an environment where serious disruptions of normal life and infrastructure may occur affecting communications, transportation and utilities (water, electricity, gas, sewage), and logistics, human resources and supplies. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=62 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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Clear procedures establishing measures to be taken before, during and after a tsunami, in particular, and for any external event, in general, adopted for design bases need to be prepared, implemented and exercised during the operation of the nuclear installation. |
For well defined tsunamigenic (fault controlled) sources, a large earthquake will always precede the tsunami and, consequently, if the source is located near the site, the vibratory ground motion will provide a warning. If the source is located at a large distance from the site, warnings from international and national tsunami notification centres are available. For all types of tsunami that may occur at the site, notification from the national and/or international tsunami warning system needs to be transmitted to the control room for immediate operator actions. In addition, a clear procedure needs to be followed by plant management in preparing for a possible tsunami until the warning is lifted. It is also important to coordinate post-earthquake procedures with those of the tsunami response, as an imminent tsunami would likely affect the possible inspections related to post-earthquake actions. Moreover, as a consequence of a major natural disaster, a severe disruption to the plant may have occurred, and the plant state (with degraded systems and degraded physical conditions of the SSCs) may have lost robustness and may have degraded the defence in depth conditions with respect to the design condition level. The safety profile of the plant needs to be well understood (i.e. the SSCs required for fulfilling the fundamental safety functions) for different plant states (e.g. shutdown), to ensure consistent protection of the plant in case of the occurrence of consequential and/or independent natural events (e.g. aftershocks following the main extreme earthquake or other natural events, such as strong winds) which may be generated during an extended period when plant recovery and upgrading actions are being taken. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=63 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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Provisions need to be made for ensuring fundamental safety functions in case of loss of DID Level 3, including core cooling, spent fuel cooling and containment integrity. |
Robust equipment to manage DID Level 4 provides the operators with greater capability to prevent an accident from progressing. For example, operation of the containment vent valves manually from a nearby shielded location would allow for the depressurization of the containments to aid in heat removal. Similarly, opening the SRVs from a nearby shielded location would have depressurized the reactors and allowed water injection to remove heat from the cores. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=92 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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Personnel need to be trained to manage severe plant conditions (Level 4). This training needs to include consideration of the extreme environmental conditions which may prevail during a severe accident. |
Although the operators had severe accident operating procedures available, the equipment and training on its use proved to be ineffective. Moreover, the possibility of a multi-unit severe accident or of an accident which simultaneously impacted other nuclear stations or damaged the local infrastructure had not been considered. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=92 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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Defence in depth Level 4 provisions need to be independent from those of Level 3. They need to be sufficiently flexible and robust to make options for SAM available to the operators. |
Although it is not possible to provide mitigating equipment for all possible severe accidents, thought needs to be given to providing the operators with flexible and robust options that would allow them to respond to several plant situations. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=92 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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Interconnections between units need to be designed to prevent an accident from migrating from one unit to another. |
The interconnection between Units 3 and 4 caused the migration of hydrogen from Unit 3 to Unit 4, causing an explosion in the Unit 4 reactor building. This explosion further complicated the response to the event by causing resources to be diverted to address the situation. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=92 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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Critical instrumentation needs to be designed and maintained so that it continues to function during severe accidents. |
Equipment important for providing information about the plant status needs to be resistant to severe accident conditions. For example, with instrumentation available in Units 1–3, the operators would understand what was happening in the reactors and would be able to take action to further mitigate the consequences of the event. Similarly, operator awareness of the real condition of the SFP in Unit 4 would have enabled them to know that, in spite of the explosion, there was no immediate threat from the fuel in the SFP in Unit 4. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=92 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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Provision needs to be made for the removal of decay heat by alternative means (such as mobile equipment) should the permanently installed equipment not be operable. |
The operators were aided in their attempts to restore cooling to the reactors by the connections that had been installed based on the experience of the Niigata-Chuetsu-Oki earthquake that affected the Kashiwazaki-Kariwa NPP in 2007. This allowed them to use diesel driven fire pumps or mobile pumpers to inject water into the reactors to cool the cores. This equipment needs to be reliable and diverse and has to be inspected regularly and tested to ensure its operability under station blackout conditions. |
| Reference Document:
The Fukushima Daiichi Accident - Technical Volume 2 - Safety Assessment |
| Link to Reference Document:
<a href=http://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV2-Web.pdf#page=92 target='_blank' alt='Open site in new window'><img src='/FukushimaLessonsLearned/Images1/Thumbnails/external-link-xxl.gif' style='height:25px; width:25px;' /></a> |
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