Fukushima Nuclear Accident – Monday 21 March update

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 Grid

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.

Here’s an excerpt on radiation measurements:

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.

Some other interesting reads from the last day or two:

1. Dan Yurman from Idaho Samizdat reviews the last weeks’ events, and asks some pointed questions about NRC Head Jaczko’s sources of information:

What remains to be known is how much distrust and incomplete information played a role in what has turned out to look like a decision that didn’t have to be made in time for a congressional hearing. Yes, that’s hindsight, but these questions deserve answers and soon.

2. Rod Adams from Atomic Insights has a lot more details on the possibility (or lack thereof) of a zirconium fire in the spent fuel ponds. His bottom line:

Despite all previous word, a fire in any used fuel pool is a fantasy that will only occur in a simplified model. It is not a concern in the real world of water, metal and ceramics. (Note: I struggled with whether or not I should waffle and couch that statement with “in my opinion”, but decided against it. Please feel free to conduct experiments that would prove me wrong.)

3. Charles Barton from Nuclear Green looks at some lessons from Daiichi:

If the Dai-ichi crisis fails to teach us the importance of moving forward on the implementation of a more advanced and safer nuclear technology, it would be a tragedy.

In the coming weeks, I will also be dissecting this new lesson of history on BraveNewClimate. But I want to wait a little longer yet — at least until all those units are in cold shutdown and the spent fuel pools are lukewarm once again!

The the Japan Atomic Industrial Forum has provided their 19th reactor-by-reactor status update (10:00 March 21):

 

Finally, here is the latest FEPC status report:

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• Radiation Levels
  • At 07:00PM (JST) on March 20, radiation level outside main office building (approximately 1,640 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 2,623 micro Sv/hour.
  • Measurement results of ambient dose rate around Fukushima Nuclear Power Station announced at 4:00PM and 7:00PM on March 20 are shown in the attached two PDF files respectively.
  • For comparison, a human receives 2,400 micro Sv per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6,900 micro Sv per scan.
• Fukushima Daiichi Unit 1 reactor
  • At 3:00PM on March 20, pressure inside the reactor core: 0.187MPa.
  • At 3:00PM on March 20, water level inside the reactor core: 1.7 meters below the top of the fuel rods.
  • At 3:00PM on March 20, pressure inside the primary containment vessel: 0.17MPaabs.
  • As of 6:00PM on March 20, the injection of seawater continues into the reactor core.
  • As of 7:00PM on March 20, activities for recovering the external power supply are underway.
• Fukushima Daiichi Unit 2 reactor
  • At 3:00PM on March 20, pressure inside the reactor core: -0.016MPa.
  • At 3:00PM on March 20, water level inside the reactor core: 1.4 meters below the top of the fuel rods.
  • At 3:00PM on March 20, pressure inside the primary containment vessel: 0.125MPaabs.
  • At 3:05PM on March 20, injection of seawater into the spent fuel storage pool has begun, until 5:20PM (total about 40 tons)
  • As of 3:46PM on March 20, the distribution board began to receive the external power.
  • As of 6:00PM on March 20, the injection of seawater continues into the reactor core.
• Fukushima Daiichi Unit 3 reactor
  • At 4:00PM on March 20, pressure inside the reactor core: 0.119MPa.
  • At 4:00PM on March 20, water level inside the reactor core: 1.65 meters below the top of the fuel rods.
  • At 4:00PM on March 20, pressure inside the primary containment vessel: 0.290MPaabs.
  • As of 6:00PM on March 20, the injection of seawater continues into the reactor core.
  • As of 7:00PM on March 20, about 2,605 tons of water in total has been shot to the spent fuel storage pool.
  • As of 7:00PM on March 20, activities for recovering the external power supply are underway.
• Fukushima Daiichi Unit 4 reactor
  • At 8:20AM on March 20, 10 Self Defense Force vehicles began to shoot water aimed at the spent fuel pool, until 9:29AM.
  • As of 7:00PM on March 20, about 83 tons of water in total has been shot to the spent fuel storage pool.
  • As of 7:00PM on March 20, activities for recovering the external power supply are underway.
• Fukushima Daiichi Unit 5 reactor
  • At 2:30PM on March 20: cold shutdown
  • At 4:00PM on March 20, the temperature of the spent fuel pool was measured at   95.2 degrees Fahrenheit.
• Fukushima Daiichi Unit 6 reactor
  • At 10:14PM on March 19, ump for Residual Heat Removal (RHR) started up and cooling of spent fuel storage pool has started.
  • At 4:00PM on March 20, the temperature of the spent fuel pool was measured at   82.4 degrees Fahrenheit.
• Fukushima Daiichi Common Spent Fuel Pool
  • At 09:00AM on March 19, the temperature of the spent fuel pool was measured at 134.6 degrees Fahrenheit.

Our official sources are:

• Office of The Prime Minister of Japan
• Nuclear and Industrial Safety Agency (NISA)
• Tokyo Electric Power Company (TEPCO) Press Releases
• Ministry of Education, Culture, Sports, Science and Technology (MEXT)