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as of July 20, 2023
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ALPS treated water, etc.
ALPS treated waterApprox. 30%
Water to be re-purifiedApprox. 70%
Sr removed water
Approximately
1.37 million m³
1,333,254m³
8,359m³
98%
At the Fukushima Daiichi Nuclear Power Station, the radioactive substances in contaminated water are removed using a multi-nuclide removal equipment (ALPS) etc., and the resulting
ALPS treated water, etc. and Sr removed water is stored in tanks on site.
1046* storage tanks are being used for ALPS treated water, etc., including 30 tanks for measurement and confirmation. There are 24* storage tanks for Sr removed water. 12 storage tanks are being used for fresh water treated with RO facility and 1 tank is being used for concentrated seawater.
* 1 Sr removed water tank will be used as the ALPS treated water tank. The number indicates the number of tank which is used as the ALPS treated water tank.
A L P S t r e a t e d w a t e r
W a t e r t o b e - p u r i f i e d
(As of March 31, 2023)
*Only completely filled tanks (including repurposed tanks) were used to calculate the amount, so this amount may differ from the entire amount of stored water.
Amount of ALPS treated water and water to be re-purified broken down by the sum of the ratios to regulatory concentrations limits (estimate)
Repurposed tanks (Water to be re-purified)
79,000m³
Currently, ALPS treated water, etc. is being stored in tanks after most of the radionuclides have been removed, with the exception of tritium. Multi-nuclide removal equipment is capable of removing radioactive substances (excluding tritium) to the point where the concentrations of these substances are lower than the regulatory concentrations limits set for discharge into the environment, which are part of national regulatory standards pertaining to contaminated water. However, due to equipment malfunctions at the beginning of the facility operation and different operational objectives at the time , the current amount of treated water being stored broken down by the sum of the ratios to regulatory concentrations is as shown in the above diagram.
More detail at the radioactive concentrations of each storage tank area
More detail at ALPS treated water, etc. data from the ALPS outlet
The Japanese government’s standard for storing ALPS treated water, etc. at the Fukushima Daiichi Nuclear Power Station stipulates that the “effective dose at site borders of 1mSv/year or less,” Since FY2013 we have been purifying contaminated water with multi-nuclide removal equipment (ALPS) and as of the end of FY2015 had achieved our goal of reducing the effective dose rate at site borders to below 1mSv/year. After achieving this goal, ALPS continued to be operated with the intention of reducing risks at the power station.
How is contaminated water generated?
The site border dose rate during 2013, when highly radioactive contaminated water from which only cesium had been removed was being stored in tanks on site, was 9.76mSv/year, thereby greatly exceeding the “effective dose at site borders of 1mSv/year or less,” which was the standard stipulated by the government.
The multi-nuclide removal equipment (ALPS) was put into operation in 2013 and equipment operation rate was increased to purify contaminated water and quickly reach the objective of reducing effective dose rates at site borders to below 1 mSv/year.
As a result of purifying contaminated water with the ALPS, the effective dose rates at site borders was reduced to below 1 mSv/year by the end of FY2015. However, due to nonconformances with the ALPS equipment, cases that regulatory concentration limits were exceeded were confirmed,
The multi-nuclide removal equipment (ALPS) enabled much progress to be made with contaminated water treatment thereby causing the amount of treated water to exceed the storage capacity of constructed tanks and we started to run out of tanks to store treated water.
In addition to accelerating the construction of tanks to store the treated water, the purification capacity of ALPS was leveraged and equipment operated while keeping in mind the regulatory concentration limits for each type of radionuclide.
As a result of leveraging ALPS purification capacity, in comparison to FY2013~FY2015, the percentage of cases where the regulatory concentration limits were exceeded decreased.
Water being stored in bolt-tightened flanged tanks, which pose a high risk of leaking, will be treated as quickly as possible.
All water stored in flanged tanks shall be treated with the multi-nuclide removal equipment (ALPS) by the end of FY2018 while maintaining effective dose rates at site borders at below 1 mSv/year and increasing the operation rate of ALPS in an effort to reduce risk.
The operation rate of ALPS was increased while keep in mind the objective of reducing risks associated with water stored in flanged tanks. As a result, while the treatment of all the Sr removed water (water that had yet to be treated with ALPS) stored in flanged tanks was completed in November 2018, the percentage of cases where the regulatory concentration limits were exceeded increased compared to FY2016.
Additionally, transfer of all ALPS-treated water stored in flanged tanks to welded tanks was completed in March, 2019.
We are thoroughly implementing measures to handle the ALPS treated water, etc. stored in tanks based on the "Basic Policy on the Handling of ALPS Treated Water at the TEPCO HD Fukushima Daiichi Nuclear Power Station" that was decided on by the government on April 13, 2021.
When discharging ALPS treated water into the sea, we shall abide by all legal safety regulations, etc., and also relevant international law and customs. In addition, we should confirm that the water being discharged is safe through radiation impact assessments* for people and the environment, and ensure that the public, surrounding environment, and agricultural, forestry and fishery products, are safe.
If ALPS treated water, etc. is to be discharged into the environment during the course of handling this water, it will be purified with multi-nuclide removal equipment until the concentrations of radioactive substances, excluding tritium, fulfill government safety regulations (sum of the ratios to regulatory concentrations is less than 1).
When discharging the water, it will be mixed with taken seawater and fully diluted. No more than 22 trillion Bq of tritium water shall be discharged annually, which was the discharge management objectives for the Fukushima Daiichi Nuclear Power Station prior to the accident, but this target may be revised as needed in conjunction with decommissioning progress.
* Including the potential impact on the sea environment
One of the systems used to purify contaminated water that has been generated at the Fukushima Daiichi Nuclear Power Station. With the exception of tritium, this equipment can remove most of the radionuclides present in contaminated water.
Click here for details
Contaminated water from the Fukushima Daiichi Nuclear Power Station that has been purified and is being stored in tanks at the power station site. There are two types of treated water. “Sr removed water” is water from which cesium (Cs) and strontium (Sr) have been removed, and “ALPS treated water, etc.” is Sr removed water from which most radionuclides, except for tritium, have been removed.
Click here for details
ALPS treated water, etc. is now stored in welded tanks, which have larger storage capacity and are less likely to leak.
Double dikes constructed around tanks prevent water from flowing beyond a certain point in the event of a leak.
Tank area are patrolled and water levels continuously monitored in order to be able to quickly respond to leak risks.
We considered using other types of tanks such as “large-capacity tanks,” “underground tanks,” and “Floating shore tank,” but ultimately decided to store the ALPS treated water, etc. in welded tanks.
Water treated with multi-nuclide removal equipment (ALPS) so that the concentrations of radioactive materials other than tritium sufficiently satisfy regulatory standards for safety (sum of ratios of legally required concentrations, excluding tritium, is less than 1) shall be referred to as, “ALPS treated water.”
Water that has been purified with multi-nuclide removal equipment (ALPS), but for which the concentrations of radioactive materials do not meet regulatory standards for safety (sum of ratios of legally required concentrations, excluding tritium, is 1 or higher) shall be referred to as, "Treated water to be re-purified."
The term “ALPS treated water, etc.” shall be used when referring collectively to both types of water.
Water from which most radionuclides, with the exception of tritium, have been removed using the multi-nuclide removal equipment (ALPS), which is equipment used for purifying contaminated water generated at the Fukushima Daiichi Nuclear Power Station.
Click here for more details on the ALPS
The Japanese government has two regulatory standards for contaminated water:
1.Standards for water that is to be stored in tanks(effective dose rate at site borders)
2.Standards for discharging water into the environment(regulatory concentrations)
Click here for more details on Treatment History
National laws and regulations※ that stipulate the radioactive concentration limits for each radionuclide if radioactive substances from the Fukushima Daiichi Nuclear Power Station are to be discharged into the environment.
※Public Notification of Requirements for the Safety of the TEPCO Fukushima Daiichi Nuclear Power Station and the Protection of Specific Nuclear Fuel Material
Japanese laws and regulations stipulate the radioactive concentration limits for each radionuclide (regulatory concentration limits) if radioactive substances are to be discharged into the environment. Since the regulatory concentration limits differ for each radionuclide, when discharging multiple radioactive substances, the ratios to regulatory concentrations are calculated for each radionuclide and the total is referred to as the "sum of the ratios to regulatory concentrations”
※Public notice of Requirements for the Safety of the TEPCO Fukushima Daiichi Nuclear Power Station and the Protection of Specific Nuclear Fuel Material
The Nuclear Regulation Authority requires that additional doses (additional doses newly given off by the power station facility that exclude naturally occurring radiation) posed on site borders from rubble and contaminated water stored at the power station site must be under 1mSv/year. This “effective dose at site borders” is used as a safety management standard when storing ALPS treated water, etc. in tanks on site.
※These images are for illustrative purposes only.
