FY2024 Sea Area Monitoring Results
(concentrations of tritium in seawater)
Tritium concentrations obtained sea area monitoring within a 3km of the power station are well below our operational index (discharge suspension level: 700Bq/L).
[Click here for details of operational indices]
| Results of quick tritium measurement* | ||
|---|---|---|
| Round | Within a 3km of the power station | Within a 10km square in front of the power station |
| 1st | Max. 29 Bq/liter | Below the detection limit |
*Measurement performed with a detection limit of approx. 10Bq/liter in order to obtain the results quickly.
Comparison of concentration of tritium in seawater
*1: This standard has been stipulated based on the calculation that if a person were to drink approximately 2L of the water coming out of the discharge outlet of a nuclear facility every day for one year, his/her exposure would be 1mSv.
*2: Source: Environmental Radioactivity and Radiation in Japan (Period: April 2019 to March 2022)
FY 2024 Discharge History
（as of May. 7, 2024）
Annual accumulated ALPS treated water discharge volume
00,000㎥
Total accumulated ALPS treated water
discharge volume since the commencement
of discharge in August 2023:
00,000,000
Annual accumulated tritium discharge volume
Approx.0trillion Bq
Total accumulated tritium discharge volume
since the commencement of discharge
in August 2023:
Approx.00trillion Bq
Annual discharge limit of tritium:
22 trillion Bq
Discharge history for each discharge
| Analysis results of ALPS treated water prior to dilution | ALPS treated water discharge history | ||||||
|---|---|---|---|---|---|---|---|
| Round | Analysis date at the measurement/ confirmation facility |
Tritium concentration |
The sum of the ratios of the concentration of each radionucide to the regulatory concentration, excluding tritium |
Discharge period | Tritium concentrations after dilution* | Amount of ALPS treated water | Amount of tritium |
| 1st | Apr. 17, 2024 |
19×104 Bq/liter |
0.31
<
Regulatory standards
1 |
Apr. 19, 2024 ~ May. 7, 2024 |
Max. 266 Bq/liter | 7,851㎥ | Approx. 1.5 trillion Bq |
| 1st | Jun. 22, 2023 |
14×104 Bq/liter |
0.28
<
Regulatory standards
1 |
Aug. 24, 2023 ~ Sep. 11, 2023 |
Max. 220 Bq/liter | 7,788㎥ | Approx. 1.1 trillion Bq |
| 2nd | Sep. 21, 2023 |
14×104 Bq/liter |
0.25
<
Regulatory standards
1 |
Oct. 5, 2023 ~ Oct. 23, 2023 |
Max. 189 Bq/liter | 7,810㎥ | Approx. 1.1 trillion Bq |
| 3rd | Oct. 19, 2023 |
13×104 Bq/liter |
0.25
<
Regulatory standards
1 |
Nov. 2, 2023 ~ Nov. 20, 2023 |
Max. 200 Bq/liter | 7,753㎥ | Approx. 1.0 trillion Bq |
| 4th | Feb. 26, 2024 |
17×104 Bq/liter |
0.34
<
Regulatory standards
1 |
Feb. 28, 2024 ~ Mar. 17, 2024 |
Max. 230 Bq/liter | 7,794㎥ | Approx. 1.3 trillion Bq |
| num | mm. dd 20yy |
n万 Bq/liter |
0.55
<
Regulatory standards
1 |
mm. 2, 2023 ~ mm. 2, 2023 |
Max. n Bq/liter | 0㎥ | Approx. 0 trillion Bq |
* Tritium concentrations in the water sampled at seawater pipe (including “uncertainty,” the accuracy of analysis)
FY2024 Discharge Plan
| Round | Discharge period | Amount of ALPS treated water |
Tritium concentration*1 | Amount of tritium |
|---|---|---|---|---|
| 1st | Apr.～May. 2024 | Approx. 7,800㎥ | 18～20×104 Bq/liter*2 | 1.5 trillion Bq |
| 2nd | May.～Jun. 2024 | Approx. 7,800㎥ | 17～19×104 Bq/liter*2 | 1.4 trillion Bq |
| 3rd | Jun.～Jul. 2024 | Approx. 7,800㎥ | 16～18×104 Bq/liter*2 | 1.3 trillion Bq |
| 4th | Jul.～Aug. 2024 | Approx. 7,800㎥ | 16～31×104 Bq/liter*2 | 1.7 trillion Bq |
| 5th | Aug.～Sep. 2024 | Approx. 7,800㎥ | 30～35×104 Bq/liter*2 | 2.4 trillion Bq |
| 6th | Sep.～Oct. 2024 | Approx. 7,800㎥ | 34～35×104 Bq/liter*2 | 2.7 trillion Bq |
| 7th | Feb.～Mar. 2025 | Approx. 7,800㎥ | 34～40×104 Bq/liter*2 | 3.0 trillion Bq |
*1 Tritium concentrations will be less than 1,500Bq/liter by dilution more than 700 times with seawater
*2 Average value of the tank group that was assessed taking into account the radioactive decay until April 1, 2024