The Japan Nuclear Safety Commission (NSC) has been criticized for not releasing its airborne plume forecasts as the Fukushima incident unfolded. At first the agency claimed that its computers were down and so it was not able to generate forecasts. Then it released a forecast that was created during the time it said its system was down. It has since released one more forecast. Meanwhile, the Japan Meteorological Agency (JMA) was running its own plume forecasts that it was supplying to the IAEA. The JMA also came under scrutiny for not releasing its plume maps. These events are covered in this prior post. Missing is a continuous sequence of forecasts of plume trajectories that the public can view to understand the basis for the Japanese government’s decisions.
Starting tomorrow and going forward, the NSC (which runs the SPEEDI plume prediction model) is planning to release plume forecasts using a low-level release (1 becquerel of radioactive iodine an hour) as the source term. [Update: on the Japanese language NSC site, the plume forecasts going back to March 11 have also been posted.]
Explaining the decision to begin releasing plume forecasts: “Goshi Hosono, a special adviser to Prime Minister Naoto Kan, apologized to the public Monday for the lack of information. Speaking at the first-ever news conference by the government’s Fukushima accident task force, where he is the administrative chief, he blamed poor interagency coordination.”
In related developments, the retrospective assessment of the radiation released into the atmosphere continues: “Data released by the government [Cabinet Office’s Nuclear Safety Commission on Saturday] indicates radioactive material was leaking into the atmosphere from the Fukushima No. 1 nuclear power plant in early April in greater quantities than previously estimated.” [ a >6-fold increase over their earlier estimates (154 terabecquerels/day vs. 24 terabecquerels/day)] As the story just cited indicates, an additional ~10,000 terabecquerels is expected to be released into the atmosphere over the next 3 months as the reactors get stabilized. This release alone would qualify as a level 6+ (out of 7) on the nuclear crisis scale.
Thankfully the risk of a catastrophic release is receding. The continuing low-level radiation emissions should remain relatively local – i.e., within the prescribed evacuation zone. As of last week (Friday), the 12 mile evacuation zone has begun to be officially enforced.