Designing, planning, and managing resilient cities: A conceptual framework

The Fukushima Daiichi Accident consists of a Report by the IAEA Director General and five technical volumes. It is the result of an extensive international collaborative effort involving five working groups with about 180 experts from 42 Member States with and without nuclear power programmes and several international bodies. It provides a description of the accident and its causes, evolution and consequences, based on the evaluation of data and information from a large number of sources available at the time of writing. The set contains six printed parts and five supplementary CD-ROMs.

The Fukushima Daiichi Accident

Nuclear power and associated activities are never far from scrutiny, the apparent advantages of the technology are juxtaposed by the risk of incidents perceived as being catastrophic. If a major nuclear incident was to occur, an important aspect of the response management to any radionuclide release would be the need to rapidly establish the spatial distributions and quantities of these released radionuclides, their type in addition to their corresponding activity. The data received from surveys would directly inform evacuation plans, on-site incident management strategies as well as protecting both workforce and public from harm. The disaster at the Fukushima Daiichi Nuclear Power Plant in 2011 is perhaps the best example of the requirement for real time data collection to inform crucial decisions. Previous reviews of the event have observed that because the static on-site radiation detector network was destroyed by the 15 m high tsunami following the magnitude 9.0 Great Tōhoku earthquake, it was not possible to immediately determine the radionuclide activity in the area and the danger presented to the responding workforce. Such preceding works have retrospectively highlighted the usefulness of unmanned aerial systems in providing real-time data within nuclear and non-nuclear settings. The establishment of an arbitrary 20 km exclusion zone surrounding the Fukushima Daiichi plant, with the displacement of over 150,000 people, has been viewed by many as an over-reaction – with many not having been required to be evacuated. This review examines and evaluates the previous as well as current work on aerial radiation monitoring and the future improvement that might be delivered by a combined three-dimensional 3D radiation mapping platform. Combining detailed 3D topographical mapping with radiation surveying has powerful implications for the way that radiological contamination across a site might be measured and displayed in the future, both following radiological release events and in routine site monitoring.

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Airborne radiation mapping: overview and application of current and future aerial systems

In this report, we have reviewed the basic features of the accident processes and radioactivity releases that occurred in the Chernobyl accident (1986) and in the Fukushima-1 accident (2011). The Chernobyl accident was a power-surge accident that was caused by a failure of control of a fission chain reaction, which instantaneously destroyed the reactor and building, whereas the Fukushima-1 accident was a loss-of-coolant accident in which the reactor cores of three units were melted by decay heat after losing the electricity supply. Although the quantity of radioactive noble gases released from Fukushima-1 exceeded the amount released from Chernobyl, the size of land area severely contaminated by (137)Cesium ((137)Cs) was 10 times smaller around Fukushima-1 compared with around Chernobyl. The differences in the accident process are reflected in the composition of the discharged radioactivity as well as in the composition of the ground contamination. Volatile radionuclides (such as (132)Te-(132)I, (131)I, (134)Cs and (137)Cs) contributed to the gamma-ray exposure from the ground contamination around Fukishima-1, whereas a greater variety of radionuclides contributed significantly around Chernobyl. When radioactivity deposition occurred, the radiation exposure rate near Chernobyl is estimated to have been 770 μGy h(-1) per initial (137)Cs deposition of 1000 kBq m(-2), whereas it was 100 μGy h(-1) around Fukushima-1. Estimates of the cumulative exposure for 30 years are 970 and 570 mGy per initial deposition of 1000 kBq m(-2) for Chernobyl and Fukusima-1, respectively. Of these exposures, 49 and 98% were contributed by radiocesiums ((134)Cs + (137)Cs) around Chernobyl and Fukushima-1, respectively.

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Comparison of the accident process, radioactivity release and ground contamination between Chernobyl and Fukushima-1

This study demonstrates how naturalistic decision-making (NDM) can be usefully applied to study ‘decision inertia’ – Namely the cognitive process associated with failures to execute action when a decision-maker struggles to choose between equally perceived aversive outcomes. Data assessed the response and recovery from a sudden impact disaster during a 2-day immersive simulated emergency response. Fourteen agencies (including police, fire, ambulance, and military) and 194 participants were involved in the exercise. By assessing the frequency, type, audience, and content of communications, and by reference to five subject matter experts’ slow time analyses of critical turning points during the incident, three barriers were identified as reducing multiagency information sharing and the macrocognitive understanding of the incident. When the decision problem was non-time-bounded, involved multiple agencies, and identification of superordinate goals was lacking, the communication between agencies decreased and agencies focused on within-agency information sharing. These barriers distracted teams from timely and efficient discussions on decisions and action execution with seeking redundant information, which resulted in decision inertia. Our study illustrates how naturalistic environments are conducive to examining relatively understudied concepts of decision inertia, failures to act, and shared situational macrocognition in situations involving large distributed teams.

Practitioner points
Researchers can use NDM to explore the cognitive processing associated with failures to act/decision inertia.
Complexities in the decision-making environment of a multiteam system (e.g., non-time-bounded choice, large team size, and lack of strategic goals) are associated with decision-making failures.
Barriers cause decision inertia as teams focus on redundant intra-agency information seeking rather than cooperative interagency communications.
Strategic direction is especially important for shifting multiteam system communication towards interagency discussions on action execution.

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M. Karir

Papers

The official report of the Fukushima Nuclear Accident Independent Investigation Commission : executive summary