According to the Board of Audit's investigation of the decontamination performed after the accident at TEPCO's Fukushima Daiichi nuclear power plant, when measuring how the radiation level changed before and after the work, the interval was 8 months or more on average. I found out that it was placed.
The Board of Audit has requested the Ministry of the Environment to measure promptly so that the effect of decontamination can be confirmed.
Decontamination was carried out in eight prefectures to remove radioactive materials released in the accident at TEPCO's Fukushima Daiichi nuclear power plant, and some of Fukushima prefectures are still in business.
When the Board of Audit investigated the status of decontamination at the request of the Diet, there was a large difference in the interval between radiation measurement before the start and after the end of the work in order to confirm the effect of decontamination. Was occurring.
As a result of summarizing the situation of about 560,000 places where the measurement was performed, ▼ less than 180 days was 43%, ▼ 180 days or more and less than 1 year was 35%, and ▼ 1 year or more was 22%.
The average was 245 days, which exceeded eight months, and in some cases nearly three and a half years had passed, and the Ministry of the Environment explained that it was measured after decontamination of a certain range was completed. ..
Radiation levels usually decrease over time due to natural attenuation and the effects of rain.
The Board of Audit has requested the Ministry of the Environment to measure promptly at future sites with as constant an interval as possible so that these effects can be eliminated as much as possible and the effect of decontamination can be confirmed.
In addition, at 12,894 locations, which is 2% of the total, the radiation dose did not decrease after the work, and the Board of Audit said that the decontamination effect could not be confirmed at these locations.
The Ministry of the Environment said, "We have already reviewed the measurement intervals. There are some places where the radiation dose does not decrease even after decontamination due to individual circumstances such as terrain. We will continue to strive for proper work." ..
Also pointed out the disposal and storage status of waste generated by decontamination
The Board of Audit also pointed out the status of final disposal and storage of soil and waste generated by decontamination.
The Ministry of the Environment is aiming to reduce the amount of final disposal by reusing soil produced by decontamination whose concentration of radioactive substances is below a certain level in public works projects nationwide.
However, the current Ministry of the Environment estimates do not take into account the soil produced by decontamination in the "Specified Reconstruction and Rehabilitation Base Area," which aims to lift evacuation orders by the spring of next year. We requested that we estimate the amount of soil generated and the concentration of radioactive substances and proceed with efforts toward final disposal.
In addition, the Ministry of the Environment manages temporary decontamination sites and contaminated waste storage sites, totaling about 550 locations, and it has not been confirmed whether they are included in the tsunami inundation area. After confirming, the Board of Audit requested that measures be taken to prevent the outflow.