TEPCO Completes Second Round of Fukushima Treated Water Discharge
The Tokyo Electric Power Company Holdings (TEPCO) has concluded the second round of its 2024 fiscal year treated water release from the Fukushima No. 1 nuclear power plant into the Pacific Ocean. According to official TEPCO reports, the discharge involved approximately 7,900 tons of water containing residual tritium, processed through an undersea tunnel after dilution with seawater. Operations concluded on June 15, 2024, one day behind the original schedule due to technical alarms.
Why Did the Discharge Schedule Experience Delays?
The discharge process faced two temporary stoppages in June caused by automated safety systems. TEPCO reported that the first pause occurred on June 10 after an alarm signaled an abnormality in the water transfer process. Technicians identified a faulty tank outlet valve as the source of the issue. After replacing the component, the utility resumed the release the following day. A second alarm triggered on June 13, which International Atomic Energy Agency (IAEA) monitoring data suggests was linked to a drop in pump flow caused by a brief power fluctuation. Operations were restored shortly after the system stabilized.
How Is Water Safety Monitored?
Both TEPCO and the Japanese government conduct continuous sampling of seawater and local fishery products. According to the Ministry of Economy, Trade and Industry (METI), all tritium concentrations measured since the start of the discharge project in August 2023 remain significantly below the government’s safety standards. These standards align with international guidelines for nuclear facility operations, which dictate that tritium levels in discharge water must be diluted to less than 1,500 becquerels per liter before release.
What Is the Long-Term Decommissioning Plan?
The release of treated water is a central component of the multi-decade decommissioning process for the Fukushima No. 1 plant, which suffered a triple meltdown following the March 2011 earthquake and tsunami. TEPCO must clear space on the plant’s premises to accommodate the infrastructure required for removing melted fuel debris. For the current fiscal year, which began in April 2024, TEPCO has scheduled a total of 62,400 tons of treated water to be released in eight separate rounds. This strategy aims to manage the volume of water stored in the facility’s extensive tank farm while allowing work on the reactor buildings to proceed.
Key Facts About the Discharge
- Total Planned Release (Fiscal Year 2024): 62,400 tons.
- Discharge Method: Dilution with seawater via an undersea tunnel.
- Primary Contaminant: Tritium (an isotope of hydrogen that cannot be removed by the Advanced Liquid Processing System).
- Regulatory Oversight: Ongoing monitoring by the IAEA and the Japanese Nuclear Regulation Authority (NRA).
Comparison: Current Operations vs. 2023
The 2024 discharge rounds follow the inaugural phase that began in August 2023. While the initial release drew significant international scrutiny, particularly from neighboring countries regarding regional food safety, the subsequent rounds have transitioned into a routine operational phase for TEPCO. Data from the Fisheries Agency of Japan indicates that despite ongoing monitoring, the impact on domestic seafood trade remains within expected fluctuations, with no radioactive levels exceeding safety limits reported in the local catch.