10 terabequerels = 10,000,000,000,000 becquerels.
The system also calculated the amount of radioactive cesium to be 1 terabecquerels/hour each for cesium-134 and cesium 137. And the Japanese government is still sitting on the data.
WSPEEDI simulation system can predict the dispersion of radioactive materials in the hemisphere, in 3D.
From what Jiji Tsushin reports, the WSPEEDI simulation was done on March 15 upon request from the Ministry of Education and Science. For whatever reason, the Ministry decided to not announce it (for that matter, not let anyone know about it, till April 3, 2012).
On the very next day, on March 16, the Ministry announced that SPEEDI and WSPEEDI would now be the responsibilities of the Nuclear Safety Commission, and instructed the Japan Atomic Energy Agency to send the data to the Commission, who either sat on it or didn't even know they were now in charge of SPEEDI/WSPEEDI.
There is another interesting bit of information in the Jiji article below. The simulation was ordered by the Ministry of Education, and one of the parameters was that radioactive materials were released at about 9PM on March 14, 2011. That's about the time (9:18PM to be exact) when 2 safety relief valves were opened in Reactor 2, probably releasing a large amount of radioactive materials through a breach in the Suppression Chamber, according to the research paper by Fumiya Tanabe of Sociotechnical Systems Safety Research Institute.
If that's the case, the government must have known that the Reactor 2 Suppression Chamber had already failed, and opening the safety relief valves would release a large amount of radioactive materials from the breach. So they ordered the WSPEEDI simulation specifying the time of the release at 9PM on March 14.
Jiji Tsushin (4/3/2012):
WSPEEDI Simulation last March: 10 terabecquerels[/hour] of radioactive iodine in Chiba, data not disclosed yet
On March 15 last year after the Fukushima I Nuclear Power Plant accident started, the WSPEEDI simulation of the dispersion of radioactive materials predicted the very high density for radioactive iodine in Chiba City in Chiba, at 10 terabequerels per hour. However, there was no effective communication between the Ministry of Education and Science and the Nuclear Safety Commission, and the data has still not been disclosed.
According to the Ministry of Education and the Nuclear Safety Commission, the WSPEEDI system is capable of simulating the dispersion of radioactive materials emitted on a hemispheric scale. The Japan Atomic Energy Agency (JAEA) operates the system, and it was conducting the calculations upon request from the Ministry of Education in March last year.
According to the calculations, as the result of radioactive materials released from Fukushima I Nuclear Power Plant at about 9PM on March 14, 2011 and dispersed, Chiba City would have 10 terabequerels/hour radioactive iodine (I-131) between 6AM and 7AM, and 1 terabequerel/hour of cesium-134 and 1 terabequerel/hour of cesium-137.
The Ministry of Education then decided that the Nuclear Safety Commission should be in charge of evaluating this data, and instructed JAEA to send the data to the Nuclear Safety Commission on the next day, March 16. JAEA sent the data as email attachments to the Nuclear Safety Commission, but the Commission didn't see the data as important, and didn't do anything. The Ministry of Education, who had received the data, did not contact the Commission and tell them the data should be made public.
I think the Ministry of Education got scared, seeing the data.
They didn't want to be the one to handle such "hot" data. So they passed it on to the Nuclear Safety Commission under Dr. Haruki Madarame, who was apparently so overwhelmed by the nuclear disaster and missing sleep that he doesn't even remember what he was doing or saying in the first 1 week of the accident.
What a luck that Japan had, having these people in the government.