International Atomic Energy Agency (IAEA) director-general Rafael Mariano Grossi on Tuesday gave the assurance that the agency would provide a continuing, objective, independent and impartial safety review during the discharging of treated water, currently stored at the Fukushima Daiichi nuclear power plant (NPP), into the sea. The assurance followed the announcement, also on Tuesday, by the Japanese government that it had asked Tokyo Electric Power Company (Tepco) to proceed promptly with its preparations to start discharging the water, in accordance with the plan approved by Japan’s Nuclear Regulation Authority.

The Fukushima Daiichi NPP, owned and operated by Tepco, was wrecked by the tsunami triggered by the massive Tōhoku earthquake in March 2011. The earthquake knocked out the primary cooling systems for the NPP, and the tsunami disabled the backup cooling systems for three of the NPP’s reactors, causing them, despite being in shutdown mode, to overheat and suffer meltdowns. The reactors had to be cooled by pumping water into them, which contaminated the water, which was then collected and stored in a rapidly-constructed tank farm at the NPP.

The Japanese plan involves releasing water that has gone through an Advanced Liquid Processing System, which removes almost all the radioactivity in the water, except for tritium. The treated water will be diluted before release, to bring its tritium levels down to below regulatory standards.

This plan was subjected to a two-year safety review by the IAEA. The agency concluded that it was consistent with the applicable international safety standards and that its radiological impact on people and the environment would be negligible.

Assuming favourable weather and sea conditions, the discharge of the treated water will start on August 24 (Thursday).

Japan and the IAEA have already agreed that the agency will have a continuing presence at the Fukushima NPP site. To this end, the IAEA opened an office at the Fukushima Daiichi NPP last month.

“IAEA staff are working there so that they can continue to monitor and assess these activities on site to ensure that they continue to be consistent with the safety standards, including on the day of the start of the discharge and after,” explained Grossi in his statement. “The IAEA will also publish available data for use by the global community, including the provision of real-time and near real-time monitoring data.”