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 29, 2011
All times listed below are Japan Standard Time (JST) unless otherwise noted.
- Radiation Levels
- On April 29, TEPCO announced the result of the analysis of water samples from the spent fuel pool at Unit 4 of Fukushima Daiichi Nuclear Power Plant taken on April 28. The concentration of radioactive nuclides were as follows:
Nuclides (half-life) | Concentration (Unit : Bq/cm3) | ||
Sampled on April 28 | (Reference) Sampled on April 12 | (Reference) Sampled on March 4 | |
I-131 (8 days) | 2.7 x 101 | 2.2 x 102 | Under the Detection Limit |
Cs-134 (2 years) | 4.9 x 101 | 8.8 x 101 | Under the Detection Limit |
Cs-137 (30 years) | 5.5 x 101 | 9.3 x 101 | 1.3 x 10-1 |
- 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 | |
4/28 6:59AM (a) | 4/28 6:54AM (b) | 4/28 2:00PM (c) | |||||
I-131 (8 days) | 1.2 x 102 | 1.4 x 101 | 1.1 x 10-2 | 4.0 x 10-2 | 3,000 | 350 | 0.28 |
Cs-134 (2 years) | 2.1 x 101 | 3.8 x 100 | 8.0 x 10-2 | 6.0 x 10-2 | 350 | 63 | 1.3 |
Cs-137 (30 years) | 2.1 x 101 | 4.0 x 100 | 7.6 x 10-2 | 9.0 x 10-2 | 230 | 44 | 0.84 |
- At 9:00PM on April 29, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 48 micro Sv/hour.
- At 9:00PM on April 29, radiation level at west gate (approximately 3,609 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 21.4 micro Sv/hour.
- Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 4:00PM on April 29 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) | 0.410 | -0.020 | -0.060 | - | 0.007 | 0.013 |
4/29 11:00AM | 4/29 11:00AM | 4/29 11:00AM | - | 4/29 1:00PM | 4/29 1:00PM | |
pressure inside the primary containment vessel (absolute pressure, MPaabs) | 0.105 | 0.075 | 0.1033 | - | - | - |
4/29 11:00AM | 4/29 11:00AM | 4/29 11:00AM | - | - | - | |
water level inside the reactor core (meter) *1 | -1.7 | -1.5 | -1.85 | - | +1.901 | +1.965 |
4/29 11:00AM | 4/29 11:00AM | 4/29 11:00AM | - | 4/29 1:00PM | 4/29 1:00PM | |
temperature of the reactor vessel measured at the water supply nozzle (degrees Fahrenheit) | 238.5 | 246.6 | 177.1 | - | - | - |
4/29 |
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