Update to Information Sheet Regarding the Tohoku Earthquake
The Federation of Electric Power Companies of Japan (FEPC) Washington DC Office
As of 10:30AM (EST), May 2, 2011
All times listed below are Japan Standard Time (JST) unless otherwise noted.
- Radiation Levels
- The concentration of radioactive nuclides from the groundwater sampled at sub-drain pits at Unit 1 to 6 of Fukushima Daiichi Nuclear Power Station were as follows:
| | Unit 1 | Unit 2 | Unit 3 | Unit 4 | Unit 5 | Unit 6 |
| Samples taken at | 4/29 9:55AM | 4/29 9:50AM | 4/29 9:41AM | 4/29 11:43AM | 4/29 10:10AM | 4/29 10:20AM |
| Nuclides (half-life) | Concentration (Unit : Bq/cm3) | |||||
| I-131 (8 days) | 8.0 x 101 | 3.1 x 102 | 3.8 x 101 | 3.2 x 10-2 | 2.0 x 10-2 | 7.9 x 10-2 |
| Cs-134 (2 years) | 6.2 x 101 | 3.4 x 101 | 5.8 x 100 | 1.2 x 10-1 | 9.8 x 10-3 | 7.3 x 10-2 |
| Cs-137 (30 years) | 7.3 x 101 | 3.8 x 101 | 6.3 x 100 | 1.3 x 10-1 | 1.4 x 10-2 | 7.8 x 10-2 |
- 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 inside the silt fence at the screen of Unit 2 | Sampled outside the silt fence at the screen of Unit 2 | Sampled at south side discharge point | Maximum Permissible Water Concentration (d) | a / d | b / d | c / d | |
| 5/1 6:57AM (a) | 5/1 6:53AM (b) | 5/1 2:00PM (c) | |||||
| I-131 (8 days) | 1.0 x 102 | 6.6 x 100 | 1.3 x 10-2 | 4.0 x 10-2 | 2,500 | 170 | 0.33 |
| Cs-134 (2 years) | 6.3 x 100 | 2.5 x 100 | 9.5 x 10-2 | 6.0 x 10-2 | 110 | 42 | 1.6 |
| Cs-137 (30 years) | 6.5 x 100 | 2.6 x 100 | 1.0 x 10-1 | 9.0 x 10-2 | 72 | 29 | 1.1 |
- At 2:00PM on May 2, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 47 micro Sv/hour.
- At 2:00PM on May 2, radiation level at west gate (approximately 3,609 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 20.1 micro Sv/hour.
- Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 4:00PM on May 2 are shown in the attached PDF file. English version is available at: http://www.mext.go.jp/
english/incident/1304082.htm - 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) | 0.448 | -0.020 | -0.064 | - | 0.003 | 0.018 |
| 5/2 11:00AM | 5/2 11:00AM | 5/2 11:00AM | - | 5/2 12:00PM | 5/2 12:00PM | |
| pressure inside the primary containment vessel (absolute pressure, MPaabs) | 0.135 | 0.070 | 0.1019 | - | - | - |
| 5/2 11:00AM | 5/2 11:00AM | 5/2 11:00AM | - | - | - | |
| water level inside the reactor core (meter) *1 | -1.65 | -1.5 | -1.85 | - | +1.729 | +2.398 |
| 5/2 11:00AM | 5/2 11:00AM | 5/2 11:00AM | - | 5/2 12:00PM | 5/2 12:00PM | |
| temperature of the reactor vessel measured at the water supply nozzle (degrees Fahrenheit) | 288.0 | 243.7 | 213.4 |
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