It's not yet time for the period of reflection and introspection on the Fukushima Daiichi crisis, but we're getting there. Even the U.S. says the worst seems to be over. The IAEA and World Nuclear News have both released new updates on the situation (the IAEA report being particularly comprehensive this time, unlike some of their earlier sparse prose). Steve Darden at Seeker Blog has done an excellent job at extracting the key snippets of information, and so I reproduce his efforts below:Offsite grid power has been brought to the Daiichi site, and is in the process of connection to each reactors equipment.
Restoration of GridHere’s an excerpt on radiation measurements:
Progress has been achieved in restoring external power to the nuclear power plant, although it remains uncertain when full power will be available to all reactors. Off-site electrical power has been connected to an auxiliary transformer and distribution panels at Unit 2. Work continues toward energizing specific equipment within Unit 2.
Radiation levels near Fukushima Daiichi and beyond have elevated since the reactor damage began. However, dose rates in Tokyo and other areas outside the 30-kilometre zone remain below levels which would require any protective action. In other words they are not dangerous to human health.At the MIT Nuclear Science and Engineering site, the 20 March status update is encouraging. Included in the report was a note on the actual tsunami heights at the reactor sites:
The Fukushima power plants were required by regulators to withstand a certain height of tsunami. At the Daiichi plant the design basis was 5.7 metres and at Daini this was 5.2 metres.
Tepco has now released tentative assessments of the scale of the tsunami putting it at over 10 metres at Daiichi and over 12 metres at Dainii.
In the associated WNN report, is the following IAEA graph of unit 5, 6 fuel pond temperatures.At units 1 and 2, external power has been restored. Tokyo Electric Power Company (Tepco) said it would restore functions in the central control room shared by the units so that accurate readings could again be taken from the reactor system. Next, workers will check the condition of the water supply systems to the reactor and the used fuel pond. With luck these will be able to go back into operation as they had been immediately after the earthquake on 11 March.
External power for units 3 and 4 should be in place ‘in a few days’ time’, said Tepco.
(…) Despite contradictory comments by the US Nuclear Regulatory Commission to US politicians and media, most observers in nuclear industry and regulation consider the measures taken by Japanese authorities to be prudent and appropriate.
Some other points, from NHK news reports:・TEPCO planned an operation to release air containing radioactive nuclidesinside the containment vessel at unit-3, give a situation of pressure increaseinside the containment in this morning . However, TEPCO decided not to releaseit since the pressure becomes stable later.
・Ministry of Defense performed activity of measuring surface temperature ateach of unit 1,2,3 and 4 from the sky using Helicopter to evaluate the effect ofthe operation of filling the pool with water from the ground today and yesterday.Ministry of Defense expressed the opinion that surface temperature of each unitseems to be 100 degree Celsius or below.
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