|May 21, 2013 |
Lessons from the Fukushima Nuclear Plant Crisis
The devastating March 2011 earthquake and tsunami in Japan was quickly followed by a crisis that threatened to dramatically increase the human toll and ruin the surrounding landscape for generations. The magnitude 9.03 earthquake was the most powerful known earthquake to ever hit Japan, triggering a powerful tsunami that damaged the Fukushima Daiichi nuclear power plant. The power plant’s cooling systems failed, leading to a series of equipment failures, nuclear meltdowns, and the release of radioactive materials. The event was classified as the maximum Level 7 on the International Nuclear Event Scale, making it the largest nuclear disaster since the infamous Chernobyl disaster in 1986. Years later, several hundred thousand people have been evacuated, a 20-km exclusion zone has been established, and the ramifications of the crisis continue to be analyzed.
Dr. Julie Pullen of the Department of Civil, Environmental and Ocean Engineering at Stevens Institute of Technology, is an expert in predicting chemical, biological, and radiological dispersion in coastal cities. Her work integrates ocean, atmosphere, and wave models for more accurate predictions.
As the Fukushima crisis unfolded, Dr. Pullen utilized her expertise and was involved in the initial atmospheric and oceanic modeling efforts to predict the effects of the radioactive emissions leaked into the atmosphere and ocean. Those findings have now been published by the Bulletin of the American Meteorological Society.
“The earthquake and tsunami began a chain of events that spiraled out of control. The nuclear meltdown at Fukushima emphasized the importance of accurate and reliable atmospheric and oceanic modeling,” says Dr. Michael Bruno, Dean of the Charles V. Schaefer, Jr. School of Engineering and Science. “Dr. Pullen’s analysis will help scientists, researchers, and decision-makers prepare for future emergencies.”
Dr. Pullen and her colleagues organized a special session at the annual George Mason University Conference on Atmospheric Transport and Dispersion in July 2011 to review the response to the crisis. Their conclusions include a summary of the major release events in the atmosphere and ocean during the crisis, review of the air-sea modeling tools used, analysis of the emergency response decisions, and insights and recommendations to improve prediction and response in future crises.
Spread of Radioactive Contaminants
During the catastrophe, radioactive contaminants escaped through explosions, fires, and a maneuver called “feed and bleed.” In this process, engineers pumped cold water to cool down the reactor. As the water touched the over-heating rods that make up the reactor, it boiled, releasing steam and increasing the pressure in the containment chamber. This pressure was released by venting the superheated gases, which distributed and deposited radioactive waste into the atmosphere. Additionally, the contaminated water used to cool the reactor was discharged directly into the ocean, releasing radioactive material along the coast.
In the initial days of the crisis, the focus of the forecasting community was on the events at the reactor site that could immediately endanger the surrounding population. As time went on, the focus shifted to defining the amount of radioactive material released and accumulating dosage predictions to help interpret airborne and ground-based monitoring and mapping. Weeks later, the contamination became measurable and contaminant prediction for the ocean rose significantly.
Based on the work of forecasters, the Japanese government progressively expanded evacuation orders. The evacuation radius increased from 3-km to 30-km over a matter of days. Over time, the Japanese government transitioned from circular evacuation zones to ones that took into account of contaminant deposition created by coastal circulation patterns.
Findings suggest a range of responses between over-reaction fueled by worst-case scenarios and inaction driven by uncertainty. The reactions of various agencies to the Fukushima incident provide examples of both extremes, such as overly large evacuation zones and delays in decision-making. In the first months after the accident, labs and agencies worked independently of each other, with little data-sharing. Decision-makers were unaware of modeling efforts that could have considerably informed their decisions. Participants concluded that these important communication linkages should be developed in advance of the next crisis to produce a more coordinated and effective emergency response.
In such a large nuclear power plant crisis, no single model could simultaneously account for important factors such as the transport, dispersion, and fate of radioactive material. The complex variations of the flow of the nearby bodies of water also made it particularly difficult to forecast the trajectory of contaminants into the ocean, requiring the development of improved models. According to Dr. Pullen, more accurate prediction requires a physical coupling of the oceanic and atmospheric models.
“There was a large consensus among those who participated that the primary deficiencies in the atmospheric and ocean models were related to the lack of good source-emission information, such as locations and elevations of sources, variations in mass release rates, and chemical and physical compositions,” says Dr. Pullen. “This lack of information about the source terms led to inconsistency and indecision among agencies and governments.”
A Leader in Ocean-Atmosphere Modeling
Dr. Pullen is Director of the Center for Secure and Resilient Maritime Commerce at Stevens Institute of Technology, where she uses high-resolution ocean-atmosphere modeling in order to understand and forecast the dynamics of coastal urban regions throughout the world. She pioneered the two-way integration of a high-resolution mesoscale atmosphere and ocean model for realistic applications in the coastal zone and published several award-winning research articles detailing the superior forecasts of both realms that resulted from coupling the models. Her work formed the foundation and motivation for the transition of a state-of-the-art, high-resolution, globally re-locatable integrated ocean, atmosphere, and wave model into operational use for diverse applications such as mission planning by the Navy SEALs. Dr. Pullen recently presented an updated analysis of the Fukushima crisis with new models and new data.
Learn more by visiting the Center for Secure and Resilient Maritime Commerce and Department of Civil, Environmental and Ocean Engineering, or visit Undergraduate Admissions or Graduate Admissions to apply.