The Japanese government is conducting selective evacuations of areas outside the 20 km evacuation zone and has upgraded the accident to a 7 on the INES scale.

Thoughts on those two events, along with your daily information sheet from our friends at FEPC after the jump.

Evacuations: The Japanese government is ordering a partial evacuation of communities outside the the 20 km evacuation zone.  The limited evacuations are interesting.  I suspect the Japanese government is quickly discovering that widening the evacuation zone, although desirable, is impractical given the very large numbers of people involved.

(From the comfort of Vienna and Washington, it is easy to suggest giant evacuation zones, since these officials do not have to deal with hundreds of thousands of displaced persons.) The Japanese government faces a miserable choice on evacuations.  The distance is reported as a radius, but of course the area increases as a square (pie are square, after all).

I prepared a rough approximation of how quickly increases in evacuation radius displace larger numbers of people.  Now, I just made some very crude assumptions — I simply divided the area by 2 to account for the fact that the region is coastal and used the population density of Fukshima Prefecture.  I also ignored the smaller evacuation around Fukushima Daini.  Still, the results are probably, on average, within 20 percent of the real ones — press reports for the 20 km evacuation, for example, claimed that about 110,000 people were evacuated from around Fukushima Daiichi.  I estimated 100,000, which isn’t bad for sitting around in my pajamas.

Radius (km) Area (km2) Population (est)
3 14 2,000
9 127 20,000
20 628 97,000
30 1,413 220,000
40 2,512 390,000
50 3,925 600,000
60 5,652 870,000
70 7,693 1,200,000
80 10,048 1,500,000

(Did I mention this is a half-assed back-of-the-envelope calculation?)

I think it looks pretty obvious why the Japanese government is trying to avoid another large increase in the evacuation zone.

INES Scale: Earlier I said I people were ranking the disaster at Fukushima as a 6 on the INES scale, before spending a little time discovering how baffling the ranking system really is.  (Well, baffling to me at least.) It now looks like the Japanese government is going by the total amount of radiation released (in iodine-equivalent becquerels). And has decided this is a 7.  Ladies and Gentlemen, please congratulate your silver medalists in the nuclear meltathalon: The Tokyo Electric Power Company.

Someone competent (ie “not  me”) should put together a chart with an apples-to-apples comparison of releases from Chernoby, Fukushima, Kyshtym, Windscale and Three Mile Island. Calling All Things Nuclear!

Here is my initial sense of the scale (in million terabecquerels), but please someone else actually do it!  7 Chernobyl 5.2; 7 Fukushima 0.37-0.63; 6 Kyshtym .040; 5 Windscale .007; 5 Three Mile Island –. A nice chart would really be helpful, although I am not sure release is the right measure.

And now, your daily information sheet from our friends at FEPC:

 

Update to Information Sheet Regarding the Tohoku Earthquake

The Federation of Electric Power Companies of Japan (FEPC) Washington DC Office

As of 2:00PM (EST), April 12, 2011

  • Radiation Levels

o      The concentration of radioactive nuclides from the seawater sampled at the screen device (installed to remove waste before the intake of seawater) of Unit 2 and sampled near the seawater discharge point (south side) of Fukushima Daiichi Nuclear Station were as follows:

 

Nuclides 

(half-life)

Concentration (Unit : Bq/cm3) Ratio
Sampled at the screen of Unit 2 at 7:17AM on April 11  (a) Sampled at south side discharge point at 2:00PM on April 11  (b) Maximum Permissible Water Concentration (c) a / c b / c
I-131 

(8 days)

1.4 x 102 9.5 x 10-1 4.0 x 10-2 3,500 24
Cs-134 

(2 years)

1.2 x 102 1.3 x 100 6.0 x 10-2 2,000 22
Cs-137 

(30 years)

1.2 x 102 1.3 x 100 9.0 x 10-2 1,300 14

 

o      At 4:00PM (JST) on April 12, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 76 micro Sv/hour.

o      At 4:00PM on April 12, radiation level at west gate (approximately 3,609 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 40.9 micro Sv/hour.

o      Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 10:00AM on April 12 are shown in the attached PDF file. English version is available at:    http://www.mext.go.jp/english/radioactivity_level/detail/1304082.htm

o      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.

 

  • Plant Parameters
Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6
pressure inside the reactor core (gauge pressure, MPa) 0.416 -0.023 -0.017 - 0.006 0.01
4/12 

6:00AM

4/12 

6:00AM

4/12 

12:00PM

- 4/12 

1:00PM

4/12 

1:00PM

pressure inside the primary containment vessel (absolute pressure, MPaabs) 0.195 0.09 0.1048 - - -
4/12 

6:00AM

4/12 

6:00AM

4/12 

12:00PM

- - -
water level inside the reactor core (meter) *1 -1.65 -1.5 -1.85 - +1.752 +2.368
4/12 

6:00AM

4/12 

6:00AM

4/12 

12:00PM

- 4/12 

1:00PM

4/12 

1:00PM

temperature of the reactor vessel measured at the water supply nozzle (degrees Fahrenheit) 421.2 

*2

330.4 221.7 

*2

- - -
4/12 

6:00AM

4/12 

6:00AM

4/12 

6:00AM

- - -
temperature of the spent fuel pool (degrees Fahrenheit) - 114.8 - - 96.4 89.6
- 4/12 

6:00AM

- - 4/12 

1:00PM

4/12 

1:00PM

the temperature directly above the spent fuel pool by thermography measurement (degrees Fahrenheit) 78.8 - 138.2 98.6 - -
4/12 

7:50AM

- 4/12 

7:50AM

4/12 

7:50AM

- -
temperature directly above the primary containment vessel by thermography measurement (degrees Fahrenheit) 62.6 - 69.8 - - -
4/12 

7:50AM

- 4/12 

7:50AM

- - -
temperature directly above the second containment building  by thermography measurement (degrees Fahrenheit) - 82.4 - - - -
- 4/12 

7:50AM

- - - -
Amount of water in total shot/injected to the spent fuel storage pool (tons) 90 359 – 374 5,203 1,621 - -
as of 4/12 

5:00PM

as of 4/12 

5:00PM

as of 4/12 

5:00PM

as of 4/12 

5:00PM

- -

*1: Minus figure means that water level is below the top of the fuel rods.

*2: This figure is under investigation.

 

  • Fukushima Daiichi Unit 1 reactor

o      As of 7:00PM on April 12, injection of nitrogen gas into the primary containment vessel to prevent an explosion by accumulated hydrogen gas continues.

o      As of 7:00PM on April 12, the injection of freshwater into the reactor core continues.

  • Fukushima Daiichi Unit 2 reactor

o      As of 7:00PM on April 12, the injection of freshwater into the reactor core continues.

  • Fukushima Daiichi Unit 3 reactor

o      At 4:26PM on April 12, TEPCO began to shoot freshwater aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete, until 5:16PM.

o      As of 7:00PM on April 12, the injection of freshwater into the reactor core continues.

  • Fukushima Daiichi Unit 4 reactor

o      At 12:00PM on April 12, TEPCO began to take water samples from the spent fuel pool in order to analyze radioactive nuclides to judge the condition of spent fuel assemblies stored in the pool, until 1:04PM.

  • Fukushima Daiichi Common Spent Fuel Pool

o      At 6:40AM on April 12, the temperature of the spent fuel pool: 89.6 degrees Fahrenheit.

  • Others

o      At 6:38AM on April 12, a fire was detected at the sampling building of Unit 1-4 (for sampling and researching the seawater) located at the ocean-side discharge canal.

o      At 9:12AM on April 12, a local fire department confirmed that the fire has been extinguished.

 

<INES Rating>

  • On April 12, Japanese Safety Authority (NISA: Nuclear and Industrial Safety Agency) announced that the Rating of the International Nuclear and Radiological Event Scale (INES) on the events in Fukushima Daiichi has been raised to Level 7.

o      On March 18, NISA assessed the events in Fukushima Daiichi at the INES Level 5, considering information obtained before March 18.

o      Based on the analysis of the status of reactors by the Japan Nuclear Energy Safety Organization (JNES), NISA estimated the total amount of discharged radioactive materials from the reactors of Fukushima Daiichi to the air. This estimation resulted in the value corresponding to Level 7 of INES rating*, as listed in the following table.

* The value representing radiation impact, which is converted to the amount equivalent to I-131, exceeds several tens of thousands of tera-becquerel (of the order of magnitude as 1016 Bq).

o      Although Level 7 is the highest level of INES rating, it is estimated that the amount of discharged radioactive materials to the environment at present is approximately 10 percent of the amount by the Chernobyl accident of 1986.

 

Assumed amount of the discharge from Fukushima Daiichi (Reference) 

Amount of the discharge from the Chernobyl Accident

Estimated by NISA Announced by Nuclear Safety Commission(*)
I-131 

(a)

1.3 x 1017 Bq 1.5 x 1017 Bq 1.8 x 1018 Bq
Cs-137 

 

6.1 x 1015 Bq 1.2 x 1016 Bq 8.5 x 1016 Bq
(Converted value to I-131) 

(b)

2.4 x 1017 Bq 4.8 x 1017 Bq 3.4 x 1018 Bq
(a) + (b) 3.7 x 1017 Bq 6.3 x 1017 Bq 5.2 x 1018 Bq

(Notes) The conversion of the values to be equivalent to radiation impact of I-131 regarding the NISA’s estimation and the Nuclear Safety Commission’s announcement were carried out by NISA in accordance with the INES User’s Manual.

<Effects of the aftershock which occurred at 2:07PM on April 12>

  • Fukushima Daiichi Nuclear Power Station

o      As of 3:30PM on April 12, pumping of freshwater into the reactor core for Unit 1, 2 and 3 continues.

o      As of 3:00PM on April 12, no significant changes have been detected at monitoring posts at the site.

  • Fukushima Daini Nuclear Power Station (Unit 1, 2, 3 & 4)

o      Plant operation was suspended at all units when the aftershock occurred.

o      As of 3:30PM on April 12, no significant changes have been detected at monitoring posts at the site and external power supply was maintained.

  • Onagawa Nuclear Power Station (Unit 1,2 & 3)

o      Plant operation was suspended at all units when the aftershock occurred.

o      As of 3:30PM on April 12, no significant changes have been detected at monitoring posts at the site and external power supply and cooling systems were maintained.

  • Tokai Daini Nuclear Power Station

o      Plant operation was suspended when the aftershock occurred.

o      As of 3:30PM on April 12, no significant changes have been detected at monitoring posts at the site and external power supply and cooling systems were maintained.

 

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)

 

Update to Information Sheet Regarding the Tohoku Earthquake

The Federation of Electric Power Companies of Japan (FEPC) Washington DC Office

As of 11:00AM (EST), April 11, 2011

  • Radiation Levels

o      The concentration of radioactive nuclides from the seawater sampled at the screen device (installed to remove waste before the intake of seawater) of Unit 2 and sampled near the seawater discharge point (south side) of Fukushima Daiichi Nuclear Station were as follows:

 

Nuclides 

(half-life)

Concentration (Unit : Bq/cm3) Ratio
Sampled at the screen of Unit 2 at 7:45AM on April 10  (a) Sampled at south side discharge point at 1:15PM on April 10  (b) Maximum Permissible Water Concentration (c) a / c b / c
I-131 

(8 days)

2.0 x 102 4.5 x 100 4.0 x 10-2 5,000 110
Cs-134 

(2 years)

1.6 x 102 3.6 x 100 6.0 x 10-2 2,700 60
Cs-137 

(30 years)

1.6 x 102 3.7 x 100 9.0 x 10-2 1,800 41

 

o      At 9:00AM (JST) on April 11, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 83 micro Sv/hour.

o      At 9:00AM on April 11, radiation level at west gate (approximately 3,609 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 45.2 micro Sv/hour.

o      Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 4:00PM on April 11 are shown in the attached PDF file. English version is available at:    http://www.mext.go.jp/english/radioactivity_level/detail/1304082.htm

o      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.

 

  • Plant Parameters
Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6
pressure inside the reactor core (gauge pressure, MPa) 0.416 -0.020 -0.017 - 0.006 0.018
4/11 

12:00PM

4/11 

12:00PM

4/11 

12:00PM

- 4/11 

1:00PM

4/11 

1:00PM

pressure inside the primary containment vessel (absolute pressure, MPaabs) 0.195 0.095 0.1043 - - -
4/11 

12:00PM

4/11 

12:00PM

4/11 

12:00PM

- - -
water level inside the reactor core (meter) *1 -1.6 -1.5 -1.9 - +1.909 +2.489
4/11 

12:00PM

4/11 

12:00PM

4/11 

12:00PM

- 4/11 

1:00PM

4/11 

1:00PM

temperature of the reactor vessel measured at the water supply nozzle (degrees Fahrenheit) 433.2 

*2

308.5 207.9 

*2

- - -
4/11 

6:00AM

4/11 

6:00AM

4/11 

6:00AM

- - -
temperature of the spent fuel pool (degrees Fahrenheit) - 159.8 - - 97.3 73.4
- 4/11 

12:00PM

- - 4/11 

1:00PM

4/11 

1:00PM

the temperature directly above the spent fuel pool by thermography measurement (degrees Fahrenheit) 60.8 - 132.8 89.6 - -
4/10 

7:30AM

- 4/10 

7:30AM

4/10 

7:30AM

- -
temperature directly above the primary containment vessel by thermography measurement (degrees Fahrenheit) 66.2 - 73.4 - - -
4/10 

7:30AM

- 4/10 

7:30AM

- - -
temperature directly above the second containment building  by thermography measurement (degrees Fahrenheit) - 77 - - - -
- 4/10 

7:30AM

- - - -
Amount of water in total shot/injected to the spent fuel storage pool (tons) 90 359 – 374 5,203 1,621 - -
as of 4/11 

10:30AM

as of 4/11 

10:30AM

as of 4/11 

10:30AM

as of 4/11 

10:30AM

- -

*1: Minus figure means that water level is below the top of the fuel rods.

*2: This figure is under investigation.

 

  • Fukushima Daiichi Unit 1 reactor

o      As of 4:00PM on April 11, injection of nitrogen gas into the primary containment vessel to prevent an explosion by accumulated hydrogen gas continues.

o      As of 4:00PM on April 11, the injection of freshwater into the reactor core continues.

  • Fukushima Daiichi Unit 2 reactor

o      At 10:37AM on April 10, TEPCO began to inject freshwater into the spent fuel pool, until 12:38PM (approximately 60 tons in total).

o      As of 4:00PM on April 11, the injection of freshwater into the reactor core continues.

  • Fukushima Daiichi Unit 3 reactor

o      At 5:15PM on April 10, TEPCO began to shoot freshwater aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete, until 7:15PM (approximately 80 tons in total).

o      As of 4:00PM on April 11, the injection of freshwater into the reactor core continues.

  • Fukushima Daiichi Unit 4 reactor

o      At 5:07PM on April 9, TEPCO began to shoot freshwater aimed at the spent fuel pool, with a specialized vehicle normally used for pumping concrete, until 7:24PM (approximately 90 tons in total).

  • Fukushima Daiichi Common Spent Fuel Pool

o      At 6:30AM on April 11, the temperature of the spent fuel pool: 89.6 degrees Fahrenheit.

  • Others

o      At 12:14PM on April 8, discharge of approximately 950 tons of low level radioactive water which had accumulated at the sub-drain pits of Unit 5 has completed.

o      At 6:52PM on April 9, discharge of approximately 373 tons of low level radioactive water which had accumulated at the sub-drain pits of Unit 6 has completed.

o      At 9:00AM on April 10, the removal works of debris at the site began, with a remote controlled excavation machine, until 5:00PM.

o      At 8:45AM on April 11, TEPCO began to install a double layered silt fence of approximately 120m (=394 feet) near the south sea wall of Fukushima Daiichi Nuclear Power Station in order to contain the spread of discharged radioactive water, until 10:45AM.

 

<Influences of the aftershock occurred at 5:16PM on April 11>

  • Fukushima Daiichi Nuclear Power Station

o      At 5:40PM on April 11, Unit 1 and 2 lost the external power supply and pumping of freshwater into the reactor core was suspended.

o      At 5:56PM on April 11, the external power supply was recovered at Unit 1 and 2.

o      At 5:59PM on April 11, pumping of freshwater into the reactor core was suspended for Unit 3.

o      At 6:04PM on April 11, pumping of freshwater into the reactor core for Unit 1, 2 and 3 was resumed.

o      As of 6:00PM on April 11, no significant changes have been detected at monitoring posts at the site.

o      As of 6:05PM on April 11, no abnormality has been reported in the temperature, pressure, or water levels in the reactor cores.

  • Fukushima Daini Nuclear Power Station (Unit 1, 2, 3 & 4)

o      Plant operation was suspended at all units when the aftershock occurred.

o      As of 5:51PM on April 11, no significant changes have been detected at monitoring posts at the site and external power supply was maintained.

  • Onagawa Nuclear Power Station (Unit 1,2 & 3)

o      Plant operation was suspended at all units when the aftershock occurred.

o      As of 5:45PM on April 11, no significant changes have been detected at monitoring posts at the site and external power supply and cooling systems were maintained.

  • Higashidori Nuclear Power Station

o      Plant was under periodical maintenance when the aftershock occurred.

o      As of 6:54PM on April 11, external power supply and cooling systems were maintained.

  • Tokai Daini Nuclear Power Station

o      Plant operation was suspended when the aftershock occurred.

o      As of 5:30PM on April 11, external power supply and cooling systems were maintained.

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)