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Using Ocean Modeling to Track the Movement of Nuclear Contamination: NWS Responds to the Fukushima Daiichi Disaster

Using Ocean Modeling to Track the Movement of Nuclear Contamination: NWS Responds to the Fukushima Daiichi Disaster

By Emily Senesac (emily.senesac@noaa.gov)

Editor’s Note: This story is the second of two installments.

On March 12, 2011, the day after the Fukushima Daiichi nuclear disaster occurred, NOAA and the NWS began moving swiftly to determine how to help. However, it quickly became clear that this was a disaster unlike any other -- no protocol for tracking the movement of oceanic contamination existed, the incident had occurred in the territorial waters of a foreign country, and there wasn’t much time to waste. Evacuations for those living near the site were progressively ordered, and by the evening of March 12, those within 20 km of the plant had been ordered to evacuate. 

According to Hendrik Tolman, now Senior Advisor for Advanced Modeling Systems who at that time was chief of the NWS Marine Modeling and Analysis Branch, lots of different factors came together successfully and simultaneously, each one instrumental to solving this colossal problem at “just the right time.”  

Thanks to a staff member who was familiar with tracking particles on the ocean model, Tolman and his team* were able to brief senior NOAA executives on the movement of the radioactive particles within a week of the disaster, explaining how they were “growing and moving.” The team, in close collaboration with NOAA’s National Ocean Service (NOS) and Air Resources Laboratory, proposed a three-step approach to provide actionable information on ocean contamination to decision makers:
1) Follow particles in the ocean from Fukushima to determine which ocean areas would be at risk (within a week). 
2) Assign contamination levels to these particles to provide an initial estimate for contamination levels (within a month). 
3) Provide high-quality three-dimensional ocean models (with NOS) to track the contamination (after six months), and combine into a single operational NWS model. This approach formed the core of a first-ever formal Concept of Operations (CONOPS) for dealing with nuclear contamination of the ocean.

The U.S. government immediately formed an Interagency Working Group (IWG) to deal with the Fukushima Disaster, led by then NOAA Deputy Administrator Dr. Larry Robinson. Due to the unique capabilities developed by the team, and due to sensitivities of dealing with territorial waters of a foreign nation, Tolman (as a civilian government employee) was designated as the ocean contamination lead in the IWG. As part of this effort, and in close collaboration with the Environmental Protection Agency (EPA), this effort resulted in the first-ever published guidelines for acceptable radioactive contamination of ocean water. Once stage three of the CONOPS plan was put in place, Tolman was invited by the International Atomic Energy Agency (IAEA) to develop their first ever standards and plans for dealing with radioactive ocean contaminations from events like the Fukushima disaster. With this plan in place, the NWS was able to contribute to recovery efforts, provide information to decision makers, and keep the public aware of potential dangers. 

While most operational projects end eventually, not very many begin with the end in mind. However, the model used by Tolman’s team had what he referred to as a “limited shelf life”, meaning that it would only run for as long as was necessary. 

“One of the hardest things in operations is to stop something,” Tolman explains. “So, when we did this very high-level, scientifically-accurate model for seeing how the radioactive Cesium  would move through the North Pacific, we actually knew going in that we would stop that product. This was the only time I’m aware of...that we put a model in operations with a limited shelf life.”  

So, why did Tolman approach the response this way? Simply put, Tolman and his team knew exactly when the model was going to become useless, thanks to contamination data collected from the North Pacific after the nuclear bomb testing of the 1950s and 60s. 

“We knew that, once the contamination in the model fell below the levels from the 1960s, we had to stop it.” 

In the face of possible nuclear contamination on a global scale, Tolman’s team had to decide how to release the information they were receiving from the model without fueling international panic. Tolman used the aftermath of Deepwater Horizon as a reference point, specifically the roles that social science and the media played in spreading unfounded and exaggerated information based on released data. 

One example Tolman provided involved a similar ocean model used to track contamination from Deepwater Horizon, and the data showed that one single particle ended up in the Gulf Stream and drifted to the coast of Ireland. “The next thing you have is some kind of news article that contamination is going to destroy the beach industry in Ireland,” Tolman remarks. So, the team decided to spend a little more time thinking about messaging, and came up with a (for scientists) very unique way to approach the situation: a “stoplight” presentation where each color of the stoplight indicated a different level of contamination. “We were way ahead of the curve in doing that.”

All together, Tolman’s ocean model ran for about three years. In that time, Tolman served as the White House Investigative Lead for the disaster response, flew to Vienna to work with the IAEA, and traveled to Japan to meet and work with the Japanese Government and the Tokyo Electric Power Company (TEPCO), the organization that owned the Fukushima Daiichi power plant. 

In collaborating with agencies, companies, and government bodies around the world, Tolman and the NWS were able to do something that doesn’t happen often: provide assistance on a global level. Whether foreign or domestic, the mission of the National Weather Service is to protect lives and property from weather-related events, and the ability to respond to the Fukushima Daiichi nuclear disaster was a step in the right direction. 

* In addition to Tolman, the NWS team consisted of Zulema Garaffo, Hae-Cheol Kim, Todd Spindler, Ilya Rivin, and Avichal Mehra.

Additional Reading: 

  • Fukushima Daiichi Accident https://www.world-nuclear.org/information-library/safety-and-security/safety-of-plants/fukushima-accident.aspx
  • Garaffo et al., “Modeling of 137Cs as a Tracer in a Regional Model for the Western Pacific, after the Fukushima–Daiichi Nuclear Power Plant Accident of March 2011” Weather and Forecasting, April 2016, p. 553-579. https://journals.ametsoc.org/doi/full/10.1175/WAF-D-13-00101.1