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Containment Measures begin to stabilize reactors and prevent further release of radioactive materials. -Helicopters are used to dump seawater into unit 3 spent fuel pool for the first time.
- Emergency crews begin spraying seawater into unit 3 spent fuel pool using specialized firefighting and riot control water cannons.
- Adding cool water to units 1, 2, 3 and 4 becomes the highest priority. -
Crews switch from spraying sea water to fresh water with boric acid injection.
-Boron and seawater used as emergency supply to suppress fission chain reactions in the fuel elements
-Boric acid acts as water soluble neutron absorber to control nuclear reactions.
-Fresh water is better for cooling and containment, due to less minerals that could erode the fuel elements -
Dose Levels > 1000 mSv/h detected in pit where supply cables are stored near the intake for Reactor 2
-A crack measuring 20 cm is found on the side of this pit where water is flowing out.
- Efforts begin to seal pit and minimize further leakage into the environment. -
TEPCO Releases a detailed plan of action into 3 groups that required immediate action.
- Cooling of Reactors and Spent Fuel Pools
- Mitigation/Containment of Radioactive Materials
- Monitoring/ Decontamination of Surrounding Areas -
Workers begin installation of massive steel structures known as cover buildings. With primary focus on reactors 3 & 4.
-Covers built over the damaged reactor buildings
-Helps contain radiation
-Reduces release of radioactive materials -
TEPCO determines that reactors have reached a state of cold shutdown.
-Japanese Prime Minister makes official announcement that all reactors are in state of cold shutdown
-All Units now maintained at 70 degrees Celsius
-Dose rates along periphery of site measured at ≤ 1mSv/yr. -
Tepco installed approx. 1,500 tubes filled with brine,100 feet deep, in a 1-mile perimeter around four of the plant’s reactors.
-Brine then chilled to below freezing.
-Purpose was to freeze the surrounding soil, forming a barrier around the reactor facilities.
-Government-commissioned panel gave a mixed assessment of the ice wall.
-Stating it was partially effective, but more steps were needed to prevent groundwater seepage. -
TEPCO says the site will reach the limit of its storage capacity of 1.37 million tonnes in the first half of 2024.
-Government panel recommends the contaminated water’s-controlled release into the sea.
-China, as well as South Korea, call the move “extremely irresponsible”.
-Local fishermen also voice strong opposition to the plan. -
Removal of all 566 fuel rod assemblies was completed in February 2021.
- Process took several years to complete
-Installation of fuel handling equipment and other preparations were completed February 2018.
-Removal of fuel started in April 2019. -
TEPCO announces the release of the contaminated water has begun.
-Japan says the water is treated to remove most radioactive elements except tritium.
- TEPCO dilutes water to reduce tritium to about one-seventh of the guidance level set by the World Health Organization for drinking water quality.
-Nuclear authorities, have said the plan will have a negligible impact on humans and the environment.
-Sushi Anyone??