The Handling ALPS Treated Water | Tokyo Electric Power Company Holdings, Incorporated

When discharging ALPS treated water*1 into the sea, we shall assess/measure the impacts*2 on people and the environment based upon safety standards stipulated by domestic legisltaions, international law and international practices, and confirm the safety of such discharges while also ensuring the safety of the public, the surrounding environment, as well as agricultural, forestry and fishery products.

*1 Water that has been purified with multi-nuclide removal equipment until the concentration of radioactive materials, with the exception of tritium, falls well below regulatory standards for safety.
*2 Including the potential impact on the sea environment

Discharge Process of ALPS Treated Water, etc. into the Sea

When discharging ALPS treated water into the sea, the water shall be subjected to repurification (secondary treatment) until the concentrations of radioactive materials, other than tritium, meet national standards, after which the treated water will be diluted with seawater to the point where it fully satisfies regulatory standards for tritium.

❶ Repurification

Treated water is re-purified until the concentrations of radioactive substances, with the exception of tritium, fulfill* regulatory standards for discharge just as they are.
❷ Treated Water Analysis

Third-party analysis will be used to confirm that the sum of the ratios to regulatory concentrations of radioactive substances, with the exception of tritium, is less than 1, and also to check tritium concentrations.

Discharge Process of ALPS Treated Water, etc. in to the Sea

❸ Dilution with seawater

Treated water will be diluted with seawater so that the concentrations of tritium fall well below regulatory standards
❹ Sea Area Monitoring

The monitoring of seawater and sea areas used for marine products shall be strengthened, and measurement results continuously disclosed.
Sea Area Monitoring (Plan)
Click here for analysis results for the surrounding area

Discharge Standards

The concentration of tritium in water to be discharged shall be assessed based on the concentration of tritium prior to discharge and the amount of water used for dilution, and shall be below 1500 Bq/L.
This concentration falls well below Japanese government safety regulations (regulatory concentration limit) of 60,000 Bq/L, as well as the World Health Organization's (WHO) drinking water quality guidelines (10,000 Bq/L). Annual discharge volume for the time being shall not exceed 22 trillion Bq, which was the discharge management goal for the Fukushima Daiichi Nuclear Power Station before the accident.
Annual tritium discharge volume shall be reviewed as necessary in conjunction with decommissioning progress.

※The government’s regulatory standard for the water containing tritium discharged into the environment (60,000 Bq/L) is set from a concentration that would result in an annual exposure of 1 mSv if approximately 2L of water from the discharge outlet of a nuclear facility were drunk at that concentration every day.
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Repurification (Secondary Treatment)

Multi-nuclide removal equipment can reduce the concentration of 62 types of radioactive substances (radionuclides) contained in contaminated water to levels that satisfy government regulations for discharge into the environment.
There is, however, treated water that does not satisfy standards for discharge into the environment (the sum of the ratios to regulatory concentrations is more than one). This treated water* shall be subjected to repurification (secondary treatment) until the sum of the ratios to regulatory concentrations of nuclides other than tritium, fall below 1, after which the water will be diluted so that the concentrations of tritium fall well below discharge standards prior to discharge.

Amount of water in storage broken down by the sum of the ratios to regulatory concentrations for treated water* (estimate) (as of September 30, 2021).

* Treated water that has 10 to 100, or more than 100, times the regulatory concentration of radioactive substances was generated at a time when we experienced equipment malfunctions, or when the priority was to treat as much contaminated water as possible. Percentages have been rounded, so the some of these percentages may not equal 100.
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Facilities to Secure Safety

We shall prioritize safety while taking thorough actions to minimize any adverse impact on reputation.

❶ Measurement/confirmation facility

The concentrations of radionuclides in ALPS treated water (A total of 69 nuclides, including 30 nuclides to be measured/assessed, tritium, and 38 nuclides that are not included in the nuclides to be measured/assessed among the nuclides targeted for removal by ALPS) shall be measured prior to dilution and discharge (including measurement by third-parties) to confirm that the water has been purified so that the concentrations of these radionuclides, with the exception of tritium, fall below regulatory standards for discharge into the environment.
*A total of 69 nuclides, including 29 nuclides to be measured/assessed, tritium, and 39 nuclides that are not included in the nuclides to be measured/assessed among the nuclides targeted for removal by ALPS (Until July 2024).
❷ Diluting facility

Dilute adequately using seawater of more than 100 times so that the tritium concentration after seawater dilution is less than 1,500 Bq/L※ and the annual discharge of tritium is below 22 trillion Bq.
- ・The tritium concentration after dilution by seawater will be monitored in Real Time by the flow rate of the ALPS treated water and the seawater to be diluted, and confirmed that the diluted water will be less than 1,500 Bq/L in both ratios.
- ・ALPS treated water after seawater dilution shall be sampled every day during discharge, and its tritium concentration to be confirmed well below 1,500 Bq/L, and the information will be made public promptly.
- ・For the time being, discharge shall be initiate after directly confirming the status of mixture and dilution utilizing the discharge vertical shaft prior to discharge into the sea.
※It is 1/40 of regulatory concentration limit (60,000 Bq/L), as well as approxiamtely 1/7 of the World Health Organization's (WHO) drinking water quality guidelines (10,000 Bq/L).
❸ Discharge Facility

In order to avoid impact of radioactive material in the harbor, seawater will be intake from outside the harbor.
ALPS treated water will be discharged via the discharge tunnel (approx.1km) to prevent discharged water from recirculating into the seawater taken in.
❹ Measures in the event of abnormality

In the event that the seawater pump to dilute water to be discharged shuts down, the emergency isolation valves shall be closed promptly and the discharge stopped.
Discharge shall also be stopped if abnormal values are confirmed in the sea area monitoring.
- ・Emergency isolation valves are installed at two locations for redundancy. One of these is installed inside the seawall to protect against tsunamis.

Tank Safety

The following initiatives are underway to prevent water from leaking from tanks used to store ALPS treated water.

Replacing assembled tanks with welded tanks.

Immediately following the accident, speed was of the essence and assembled (flanged tanks) tanks were used to store contaminated water. These tanks will be gradually disassembled and replaced with welded tanks for which the risk of leaks is lower. Some assembled tanks that will be left standing will be waterproofed (flange waterproofing) as part of measures to prevent leaks.

Doubled weirs and weir cover installation

Doubled weirs have been constructed around the tank area in order to prevent leaks of water outside the system. Furthermore, by installing gutters and weir covers, we can prevent the influx of rainwater into the weirs thereby ensuring that they work as designed.

Seismic-resistance

If a large force (horizontal, vertical) is applied to the tanks as a result of intense seismic motion, the structure is designed to absorb that force (that's why the foundations are not fixed). As a result, pipes that connect the tanks must have a certain degree of flexibility to move along with them.
Furthermore, when retention tanks become full, connection valves installed on both sides of connecting pipes are closed.

Tsunami countermeasures

Tanks are located on high ground more than 30m above sea level. And, more seawalls are being built.

Transfer pipe leak prevention measures

High-density polyethylene pipes that have excellent shock and weather resistance, and are often used for sewage and gas pipes, have been installed for transfering treated water.
Pipe connections have also been waterproofed.

Regular patrols

Regular patrols are conducted to confirm that there are no abnormalities in the field

The changes of additional tank installation

Before the earthquake

November, 2009
Immediately after the earthquake

May, 2011
The changes of additional tank installation

Installation of flanged tanks from March 2011 to March 2013
The changes of additional tank installation

Installation of welded tanks from April 2013 to December 2014
The changes of additional tank installation

Replacement of flanged tanks to welded tanks from January 2015 to December 2020

Contaminated Water Treatment History

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?

FY2013~FY2015
- Issues Addressed
  
  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.
- Treatment Plan
  
  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.
- Achievements
  
  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,
  
  Percentage of cases where regulatory concentration limits were exceeded based on the number of samples and broken down for each radionuclide.
  
  Total amount treated by existing ALPS, additionally installed ALPS, high-performance ALPS
FY2016
- Issues Addressed
  
  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.
- Treatment Plan
  
  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.
- Achievements
  
  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.
  
  Percentage of cases where regulatory concentration limits were exceeded based on the number of samples and broken down for each radionuclide.
  
  Total amount treated by existing ALPS, additionally installed ALPS, high-performance ALPS
FY2017~
- Issues Addressed
  
  Water being stored in bolt-tightened flanged tanks, which pose a high risk of leaking, will be treated as quickly as possible.
- Treatment Plan
  
  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.
- Achievements
  
  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.
  
  Percentage of cases where regulatory concentration limits were exceeded based on the number of samples and broken down for each radionuclide.
  
  Total amount treated by existing ALPS, additionally installed ALPS, high-performance ALPS
How ALPS treated water, etc. is to be handled going forward
- How ALPS treated water, etc. is to be handled going forward
  
  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