Please find the updated information sheet below and attached that summarizes the events from Update-39 at 10:00AM on 5/4.
For your reference, JAIF (Japan Atomic Industrial Forum) has been posting the translation of news reports on their website.
Please direct any questions regarding this document to me, Ishida@denjiren.com or Samuel Lederer, Researcher of FEPC at lederer@denjiren.com.
Update to Information Sheet Regarding the Tohoku Earthquake
The Federation of Electric Power Companies of Japan (FEPC) Washington DC Office
As of 11:40PM (EST), May 5, 2011
All times listed below are Japan Standard Time (JST) unless otherwise noted.
- TEPCO’s Plan to Flood Primary Containment Vessel of Unit 1 Reactor
- On May 5, TEPCO submitted a report to the Nuclear and Industry Safety Agency (NISA) regarding the evaluation of effectiveness and safety of TEPCO’s plan to flood the primary containment vessel of the Unit 1 reactor of Fukushima Daiichi Nuclear Power Station to the level at which the fuel in the reactor can be fully submerged in order to stably cool down the reactor.
- The report notes that this flooding will provide a margin of time in case the temperature of the spent fuel starts to increase in the event of a contingency situation such as a disruption of injecting water. It is expected that the leakage of radioactive materials from the primary containment vessel will be decreased by flooding the primary containment vessel and covering the exposed portion of the spent fuel.
- TEPCO evaluated the feasibility and safety of flooding the primary containment vessel with regard to potential changes in vessel pressure, seismic capacity, and water leakage. TEPCO confirmed that there will be no problematic issues.
- The full version of the report is available at:
- 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 | 5/4 10:53AM | 5/4 10:59AM | 5/4 11:03AM | 5/4 11:14AM | 5/4 10:43AM | 5/4 10:36AM |
Nuclides (half-life) | Concentration (Unit : Bq/cm3) | |||||
I-131 (8 days) | 1.5 x 101 | 1.5 x 102 | 1.1 x 101 | 2.2 x 10-2 | 1.5 x 10-2 | 6.0 x 10-2 |
Cs-134 (2 years) | 2.1 x 101 | 1.6 x 101 | 1.7 x 100 | 9.0 x 10-2 | Not Detectable | 6.5 x 10-2 |
Cs-137 (30 years) | 2.4 x 101 | 1.8 x 101 | 1.8 x 100 | 9.2 x 10-2 | 2.7 x 10-2 | 6.6 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 | |
5/4 6:45AM (a) | 5/4 6:42AM (b) | 5/4 1:40PM (c) | |||||
I-131 (8 days) | 3.3 x 101 | 4.9 x 100 | 1.7 x 10-2 | 4.0 x 10-2 | 830 | 120 | 0.43 |
Cs-134 (2 years) | 4.2 x 100 | 3.3 x 100 | 7.8 x 10-2 | 6.0 x 10-2 | 70 | 55 | 1.3 |
Cs-137 (30 years) | 4.2 x 100 | 3.4 x 100 | 8.5 x 10-2 | 9.0 x 10-2 | 47 | 38 | 0.94 |
- At 2:00PM on May 5, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 46 micro Sv/hour.
- At 2:00PM on May 5, radiation level at west gate (approximately 3,609 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 18.9 micro Sv/hour.
- Measurement results of environmental radioactivity level around Fukushima Nuclear Power Station announced at 7:00PM on May 5 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) | 0.460 | -0.023 | -0.074 | - | 0.006 | 0.016 |
5/5 11:00AM | 5/5 11:00AM | 5/5 11:00AM | - | 5/5 12:00PM | 5/5 12:00PM | |
pressure inside the primary containment vessel (absolute pressure, MPaabs) | 0.130 | 0.065 | 0.1038 | - | - | - |
5/5 11:00AM | 5/5 11:00AM | 5/5 11:00AM | - | - | - | |
water level inside the reactor core (meter) *1 | -1.65 | -1.5 | -2.05 | - | +2.078 | +2.258 |
5/5 11:00AM | 5/5 11:00AM | 5/5 11:00AM | - | 5/5 12:00PM | 5/5 12:00PM | |
temperature of the reactor vessel measured at the water supply nozzle (degrees Fahrenheit) | 274.5 | 242.2 | 313.9 | - | - | - |
5/5 11:00AM | 5/5 11:00AM | 5/5 11:00AM | - | - | - | |
temperature of the spent fuel pool (degrees Fahrenheit) | - | 120.2 | - | - | 104.5 | 94.1 |
- | 5/5 11:00AM | - | - | 5/5 12:00PM | 5/5 12:00PM | |
Amount of water in total shot/injected to the spent fuel storage pool (tons) | 90 | 642 - 657 | 5,390.5 | 3,306.2 | - |
[Message clipped] View entire message
No comments:
Post a Comment