Press Releases 2013

At around 9:35 AM on October 9, 2013, inside a temporary warehouse within Fukushima Daiichi Nuclear Power Station, during piping construction for the contaminated water treatment facility's desalination system (reverse osmosis membrane system) RO-3, water (to be treated by the desalination system) leaked from a joint of piping as a cooperative company worker mistakenly took off the joint, which was different from the one supposed to be taken off.

Later, we manually stopped the waste liquid supply pump upstream of the piping at around 9:55 AM, and closed a relevant valve near the piping at around 10:15 AM. Further, we reconnected the joint of the piping. At around 10:50 AM, we confirmed that the water leakage stopped as a result.

The leaked water spread all over the area surrounded by the dike inside the temporary warehouse, and did not flow out of the dike. Based on the analysis result on a sample taken on August 13, 2013 of water to be treated by the desalination system (a gross-beta value of 3.7×10⁷Bq/L), the amount of radioactivity of the leaked water in terms of gross beta apparently exceeded 1×10¹⁰Bq (a reference value below which the severity of leakage is minor). We therefore determined that the incident corresponds to "a case when nuclear fuel material (not in the form of gas) or the like has leaked within an area controlled by the company due to an unpredictable event such as a failure of a nuclear reactor facility for power generation" as per Article 18, item 12 of the regulations concerning the operational safety and the protection of specified nuclear fuel material at the TEPCO's Fukushima Daiichi NPS nuclear reactor facilities (hereinafter, "the Fukushima Daiichi regulations").
We later conducted analysis on the leaked water, which confirmed that the gross beta value of the water was 3.4×10⁷Bq/L.
Of 11 workers who were conducting the work and coping with the situation following the leakage, 6 workers were found to have radioactive material on their bodies but have no radioactive material on their faces. We confirmed that the contamination of all of the 6 workers was removed to allowable levels below the limit through decontamination.

On October 18, 2013, we submitted a report (a report of an accident or failure) concerning this trouble to the Nuclear Regulation Agency, as per Article 18, item 12 of the Fukushima Daiichi regulations.

Following this incident, we were to investigate the cause in detail, and take necessary actions. Further, we were to summarize and report the result of the investigation to the Nuclear Regulation Agency.

(Previously announced on October 9 and 18, 2013)

Concerning the leakage from RO-3, we would like to announce that we submitted today a report (a report of an accident or failure) as per Article 18, item 12 of the Fukushima Daiichi regulations to the Nuclear Regulation Agency.

< Attachment >
-Report on Failure or Like Trouble at Nuclear Reactor Facility for Power Generation (PDF 1.17MB)
(Document title: Leakage from Contaminated Water Treatment Facility's Desalination System (Reverse Osmosis Membrane System) RO-3 at Fukushima Daiichi Nuclear Power Station)
This report is available only in Japanese. We apologize for the inconvenience this may cause.

< Reference >
-Cause of and Measures against Leakage from Contaminated Water Treatment Facility's Desalination System (Reverse Osmosis Membrane System) RO-3 at Fukushima Daiichi Nuclear Power Station (PDF 228KB)