FY2023 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. 10 Bq/liter | Below the detection limit |
| 2nd | Max. 22 Bq/liter | Below the detection limit |
| 3rd | Max. 11 Bq/liter | Below the detection limit |
| 4th | Max. 16 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 2023 Discharge History
（as of Mar. 17, 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 | 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. 254 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)
FY 2023 Discharge Plan
ALPS treated water is discharged starting from which stored in the measurement/confirmation facility.
| Round | Discharge period | Amount of ALPS treated water |
Tritium concentration*1 | Amount of tritium |
|---|---|---|---|---|
| 1st | Aug. 2023 | Approx. 7,800㎥ | 14×104 Bq/liter | Approx.1.1 trillion Bq |
| 2nd | Oct. 2023 | Approx. 7,800㎥ | 14×104 Bq/liter | Approx.1.1 trillion Bq |
| 3rd | Nov. 2023 | Approx. 7,800㎥ | 13×104 Bq/liter | Approx.1.0 trillion Bq |
| 4th | Feb. 2024 | Approx. 7,800㎥ | 17×104~21×104 Bq/liter | Approx.1.4 trillion Bq*2 |
*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 July 1, 2023