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Summary of the extra news conference by Minister of Economy, Trade and Industry, Akira Amari (July 20) |
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Regardless of some effects observed in surrounding facilities, equipment and machinery, the nuclear reactor units, the most important part of the power station, automatically shut down safely as designed in the latest earthquake. |
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Release of some radioactive materials from the power station were subsequently observed, but it is confirmed today that the release from the main exhaust stack at Unit 7 has stopped.The amount of radiation released into the atmosphere thus far is ten millionth of the radiation dose people receive naturally in the course of normal life. |
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The radiation ,released to the sea, contained in contaminated water that leaked from Unit 6 is equivalent to the amount of radiation in nine liters of radon spa water and does not affect the surrounding environment. |
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Acceptance of an IAEA (International Atomic Energy Agency) investigation |
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The Governor of Niigata Prefecture has urged the government and the Minister of Economy, Trade and Industry to accept an IAEA investigation as soon as possible, saying that it is imperative to distribute accurate information to the world in order to swiftly wipe away the anxieties of local residents and the rest of the Japanese population.
The government has expressed its readiness to urgently launch specific talks on the matter with IAEA.
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Disclosure of affected locations in the power station to journalists |
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Tokyo Electric Power Company invited media reporters to view the affected sites on July 21. |
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No.1 Unit Diesel Oil Tank |
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No.3 Unit House Transformer |
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No.3 Unit Main Exhaust Duct |
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No.6 Unit Non-radioactive Storm Drain System |
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No.4 Filtrate Water Tank |
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Monitoring Post No.1 |
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Influence on nuclear fuel at the reactor core |
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At Units 2 to 7, which remain loaded with nuclear fuel, reactor water has been analyzed to confirm that there is no damage to the loaded fuel. |
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Current status of the release of radioactive materials |
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The release of radioactive materials has stopped in the two such cases identified.The amount of released radiation was negligible, and has been assessed as having no impact on the environment. The underlined sections indicate new information that has come to light since issuance of the second report.
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Unit 6 |
Unit 7 |
| Estimated causes and release routes |
Water in the spent fuel pool of unit 6 sloshed around. Some leaked into non radiation controlled area on the third floor and mezzanine, and was discharged to the sea via a discharge channel.
It is presumed that water spilled over from the spent fuel pool to the reactor building refueling floor (controlled area) subsequently dripped down to the uncontrolled area via cable and conduit of the refueling machine.
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In the operation process of automatic reactor shutdown, there was a delay in stopping the turbine’s ground exhauster.
Consequently, the residual iodine and other radioactive particulates in a condenser were drawn into the exhauster and released into the air via the exhaust stack.
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| Amount released into the environment |
Approx. 9×104 Bq (in the sea) |
Approx. 4×108 Bq (in the atmosphere) |
| Exposure dose |
Approx. 2×10-9 mSv |
Approx. 2×10-7 mSv |
| Substantially lower than 1 mSv, the legally-defined limit of radiation dose to the public per annum |
| Current status |
The release of radioactive materials has stopped |
The release of radioactive materials has stopped. The radiation readings from main exhaust stacks at Units 1 to 6 are below the limit of detection. |
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As of July 22, the power station has identified approximately 70 locations that suffered quake damage, and will continue with a detailed investigation.
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Above information will be updated as the further investigation by TEPCO will be carried forward.
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＜References＞ Tokyo Electric Power Company
Nuclear and Industrial Safety Agency
Nuclear Safety Commission of Japan
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