SPEEDI definitely out

October 9, 2014

SPEEDI radiation forecasting dropped by NRA as primary alert system

http://ajw.asahi.com/article/0311disaster/fukushima/AJ201410090062

By TOSHIO KAWADA/ Staff Writer

Japan's nuclear watchdog has decided to scrap a warning system to alert residents to evacuate in an emergency because it didn't function properly when there was a nuclear disaster.

The Nuclear Regulation Authority made the decision Oct. 8 after local governments across the country called on the body to explain how data offered by the SPEEDI radioactive fallout-forecasting system should be utilized.

The municipalities are responsible for compiling evacuation plans for residents in their areas.

The System for Prediction of Environmental Emergency Dose Information was designed to determine when local residents should be evacuated in the event of serious accidents at nuclear plants and other such facilities.

But a paucity of information in the immediate aftermath of the Fukushima No. 1 nuclear power plant disaster in 2011, such as the state of its reactors, hampered the ability of SPEEDI to forecast the spread of radioactive materials from the site.

As a result, the system was not used in making the evacuation decision as the Fukushima nuclear crisis unfolded, drawing nationwide criticism.

The NRA revised its nuclear emergency preparedness and response guidelines in February 2013.

The modified guidelines state that when a severe accident occurs, residents living within a five-kilometer radius of the disaster should evacuate immediately. Those living within 30 kilometers are urged to remain indoors and later decide whether to flee based on radiation levels measured by nearby monitoring posts.

The revised guidelines downgraded the importance of the data provided by SPEEDI, now calling it just “reference information.”

Still, even after the revision, the NRA did not clarify how SPEEDI data should be used in developing evacuation plans, which resulted in some local governments continuing to incorporate it into their evacuation strategies on the assumption that its predictions are still reliable.

The NRA said in its new SPEEDI operation manual released Oct. 8 that it will clarify how to best integrate the system’s forecasting abilities in nuclear disaster management, though it would still not be used as the primary indicator on deciding when to evacuate.

The nuclear watchdog is, for example, expected to recommend that SPEEDI be utilized to estimate exposure to radioactive iodine and other materials after a nuclear accident.