NHK TV program regarding Fukushima Daiichi Nuclear Power Station reported contents that are incorrect and could cause misunderstandings. We hereby provide facts below.
1. Changing location of the emergency diesel generators into the basement
The program reported that TEPCO had moved emergency diesel generators from the 1st floor in the turbine building to the 1st basement. However, the emergency generators have been located in the 1st basement since commencement of commercial operation started, and we have not change these locations.
2. Picture of the top of the primary containment vessel used for the proof of the influence of hydrogen explosion
In the program, a picture and narration of the top of the primary containment vessel were used to explain the influence of the hydrogen explosion of Unit 1. However, this picture was not the PCV of Unit 1 but of Unit 4, which was under refueling outage, and therefore the picture and narration is incorrect. That is to say, this top part of the PCV was what we had detached in order to replace core shroud and reactor internal components.
3. Claim on the PCV ventilation has no filtration
In the program, it was mentioned several times that there were no filters in the primary containment vessel ventilation line. However, boiling water reactors that we operate use "wetwell vent", which has scrubbing effect to mitigate emission of radioactive materials at the comparative level to the filters. That is to say, in principle, our venting procedure uses the water in the suppression chamber as filteration and we have prepared and added the necessary equipment and procedures for accident management measures. Although a document that reads "wetwell vent" was shown in the program, NHK ignored this.
In the United States, the above-mentioned "wetwell" ventilation is adopted for boiling water reactors.