IAEA Confirms Fukushima Water Discharge Meets Safety Standards in New Reports

The International Atomic Energy Agency (IAEA) has released three new analytical reports confirming that the ongoing discharge of ALPS-treated water from Japan’s Fukushima Daiichi Nuclear Power Station (FDNPS) continues to meet international safety standards. The reports validate that the process poses a negligible radiological impact on both people and the environment, reaffirming the conclusions of the Agency’s Comprehensive Report issued in July 2023.

Independent Verification Strengthens Transparency

The latest findings are part of the IAEA’s Additional Measures initiative, a framework designed to ensure independent verification of the safety and transparency of Japan’s water discharge process. The initiative enables third-party laboratories from around the world to analyse samples of treated water, seawater, and marine life collected near the discharge point.

The three newly released reports cover missions conducted in February and April 2025, during which international experts carried out on-site sampling under IAEA supervision. Laboratories from China, France, the Republic of Korea, the Russian Federation, and Switzerland, along with the IAEA’s own laboratories and Japanese national labs, participated in the independent analysis.

Director General Rafael Mariano Grossi emphasized that the inclusion of multiple countries in the verification process underscores the Agency’s commitment to transparency and scientific integrity.

“The consistency of results across all laboratories demonstrates the robustness and credibility of the IAEA’s safety review and monitoring framework,” Grossi said. “These Additional Measures ensure that the discharge process remains under rigorous international scrutiny.”

A Multi-Layered Global Analysis

The new reports evaluate data from several key stages of the discharge process, including:

1. Source Monitoring (February 2025): Sampling of ALPS-treated water before dilution with seawater to assess radioactive content.

2. Marine Environmental Monitoring (February 2025): Collection of seawater and fish samples near the FDNPS discharge outlet.

3. Discharge Monitoring (April 2025): Analysis of ALPS-treated water after dilution, prior to release into the Pacific Ocean.

Each report contains results from all participating laboratories, alongside an IAEA meta-analysis assessing data consistency, accuracy, and comparability. The results showed no meaningful deviations between national and international laboratory findings.

This scientific alignment reaffirms earlier IAEA conclusions that the controlled release of ALPS-treated water — which began in August 2023 under the supervision of the Tokyo Electric Power Company Holdings (TEPCO) — poses no measurable threat to human health or marine ecosystems when conducted as planned.

The Role of ALMERA in Global Oversight

All laboratories involved in the analyses are part of the IAEA’s Analytical Laboratories for the Measurement of Environmental Radioactivity (ALMERA) network. Established to provide independent verification during environmental radiation events, the network includes over 200 institutions worldwide with demonstrated analytical precision and technical capacity.

The ALMERA framework ensures standardized testing methodologies, allowing comparable results across international laboratories and reinforcing confidence in the data’s reliability.

Building Global Confidence Through Cooperation

The Additional Measures initiative, launched after the start of the water discharge, represents a significant expansion of international participation in monitoring activities. It was introduced in response to concerns from neighboring countries and the global community regarding the potential environmental impacts of Japan’s decision to release treated water into the sea.

The programme includes joint sampling missions, cross-laboratory comparisons, and public disclosure of findings, ensuring that each phase of the discharge — from treatment to release — remains open to international review.

The IAEA’s ongoing involvement serves as an independent assurance mechanism to verify compliance with safety standards established by the IAEA Safety Fundamentals and other international conventions.

Scientific Consensus on Radiological Safety

According to the reports, concentrations of tritium — the primary radionuclide remaining after ALPS treatment — are well below the safety limits set by both international and Japanese regulatory frameworks. Tritium, a low-energy beta emitter, is considered the least biologically hazardous of radioactive isotopes and is routinely released from nuclear facilities around the world under controlled conditions.

The IAEA reiterated that continuous environmental and marine monitoring will continue throughout the multi-decade discharge process, ensuring transparency and accountability. The Agency will publish ongoing updates as further data are verified and analysed.

Ensuring Public Trust and Environmental Protection

The publication of these latest reports marks the fourth set of Additional Measures assessments released since the first in June 2025, which covered marine sampling conducted in October 2024. Collectively, the reports have reinforced confidence that Japan’s handling of the ALPS-treated water aligns with best practices for environmental protection and radiation safety.

The IAEA has pledged to maintain its on-site presence at the Fukushima Daiichi site and to continue independent verification of future discharges.

“Transparency and scientific evidence are the cornerstones of public trust,” said Grossi. “The IAEA’s multi-country approach ensures that this process remains fully accountable to the global community.”

Looking Ahead

With these reports, the IAEA has now completed four independent verification missions since the start of the discharge. Future Additional Measures missions are planned to continue periodic monitoring of water quality, marine life, and radiation levels in and around the discharge area.

All reports are available on the IAEA’s official website and are open to review by Member States, scientific institutions, and the public — a reflection of the Agency’s enduring commitment to openness, evidence-based analysis, and environmental safety.