Japan’s Tokyo Electric Power Company (TEPCO), the Fukushima Daiichi Nuclear Power Station (FDNPS) operator, today informed the International Atomic Energy Agency (IAEA) that water containing radioactive materials was found to have leaked from a caesium absorption tower at the plant. The estimated 1,5 cubic metres (m3) of water was assessed to have leaked from a valve left open during cleaning work at the absorption tower.
(The estimated cubic metres figure was amended on 4 April 2024 following confirmation from TEPCO to the IAEA that 1,5 m3 is assessed to have leaked, not 5,5 m3 as noted on 7 February)
The leaked water was from the system filtering water as part of the ongoing decommissioning activities at the site. The event is not related to the discharge of the Advanced Liquid Processing System (ALPS) treated water.
TEPCO has confirmed that there was no significant fluctuation in radiation measurements recorded at the site. The event does not pose any risk to the public and there is no environmental impact off-site.
The IAEA was informed that at around 8:53 AM today a contractor at the FDNPS noted that water had leaked from a caesium absorption tower within the High Temperature Incinerator Building, a facility used to remove caesium and strontium from contaminated water collected at the site. Water being used to flush the valves in preparation for valve inspection leaked through an open valve. Workers at the site closed the valve at 9:10 AM and the water stopped leaking at 9:16 AM.
TEPCO conducted an assessment and confirmed to the IAEA that the leaked water is a mix of contaminated water from the absorption system and filtered water used for cleaning. TEPCO calculated that the leakage totalled around 5,5 m3 of water containing an estimated 0,022 Terabecquerel (TBq) of radioactive substances.
TEPCO assessed that the water may have resulted in minor contamination to the soil surrounding the absorption tower and has taken precautionary measures. It has restricted access to the area and has collected soil for analysis.
Japan’s Nuclear Regulatory Authority has been informed and inspectors at the plant are conducting an on-site investigation.
The IAEA remains in contact with authorities in Japan.