From NEI’s Japan earthquake launch page:
UPDATE AS OF 7:00 P.M. EDT, MARCH 24
Restoration of electric power at reactors 1, 2 and 4 at the Fukushima Daiichi nuclear power plant has led to the reconnection of important reactor instrumentation, the International Atomic Energy Agency said.
Cooling water continues to be injected into reactors 1, 2 and 3. Reactors 5 and 6 at Fukushima Daiichi remain safely shut down. Both reactors were undergoing maintenance at the time of the earthquake.
Radiation dose rates inside the containment vessels of reactors 1 and 2 have decreased slightly, IAEA said.
External power has been reconnected to the common used fuel storage pool at the plant and cooling started on March 24 at 5:05 AM EDT, according to Japan’s Nuclear and Industrial Safety Agency. About 60 percent of the used uranium fuel rods at Fukushima plant are stored at this facility.
Radiation monitoring continues
Air samples collected at on-site monitors at the Fukushima Daiichi plant March 19-23 show that only iodine-131 was found to be in excess of Japanese government limits. Radiation dose rates measured on site March 21-23 have decreased from 193 millirem to 21 millirem per hour. Radiation dose rates at the plant’s site boundary ranged from 1 millirem to 3 millirem per hour on Thursday.
At distances between 34 and 73 kilometers to the west of the Fukushima Daiichi nuclear power plant, the dose rate ranged from .06 millirem to .69 millirem per hour.
Considerable variation in the levels of reported iodine-131 and cesium-137 continues in 10 prefectures, IAEA said. Food, milk and drinking water sampling has been most thorough and extensive in the Fukushima and Ibaraki prefectures, IAEA said.
Seawater samples collected at several points 30 kilometers from the coastline near the Fukushima Daiichi nuclear power plant found measurable concentrations of iodine-131 and cesium-137, IAEA said. The iodine concentrations were at or above Japanese regulatory limits. The cesium levels were well below those limits.
For more information on iodine-131, see NEI’s fact sheet Health Impacts of Iodine-131.
Comments
Why would we care what the radiation level in the containment vessel is?
I think the containment vessel is a place where no one would be. Doesn't the reactor vessel vent to the containment vessel and the containment vessel vent to the suppression torus or optionally to the area under the roof (or the outside is the roof is gone)?
"At distances between 34 and 73 kilometers to the west of the Fukushima Daiichi nuclear power plant, the dose rate ranged from .06 millirem to .69 millirem per hour."
0.06 mr/hr. What is the normal background level and variation?
How can these help the public put it into perspective?
Please consider changing your base units, or at least including both side by side.
From searching news articles, it looks like the background radiation at Wako city next to Tokyo is 0.04 micro Sieverts/hr which works out to 0.004 mrem/hr. The average US background dose is 0.04 mrem/hr (310 mrem/8,760 hours in a year) so it looks Tokyo has quite a bit less background radiation than the US does.
As to why NEI is sticking with rem and picocuries, it's because the US hasn't adopted the SI system so that's why the NRC, EPA and industry use those numbers.
I recommend checking out our page on Japan's radiation. A lot of questions here about radiation can be found on that page.
There is radiation measuring equipment inside containments. Variations in containment radiation levels provide information that may be useful in evaluating reactor conditions. For the Japanese BWRs no one would be in the primary containment because it is filled with inert gas (nitrogen). The area under the roof is the secondary containment. Reporters generally do not know that there are two containments for each plant.
Also, I understand the premise behind not going to km from miles (it's too hard to change), but I would think that a fair percentage of those who rattle on and on and on about mrem could handle the shift to SI units. Probably not your decision.