Response and safety of agglomeration caused by cleaning of places that may become "micro spots" in nursery schools (June 4, 2019)

We have received many inquiries from nursery schools, ward offices and Child and Youth Bureau.

In Yokohama City, in elementary and junior high schools and nursery schools, accumulations such as soil, sand, dead leaves, etc. in places that may become so-called "micro spots" (*) such as under gutters and gutters were collected in September 2011. It was removed just in case.
We measure radiation dose about these and, about result is less than standard standard value of Yokohama-shi correspondence, and, about thing which we confirmed that it was safe, buried processing in each facility site.

This section describes the progress of the response so far and efforts to confirm safety.

※Micro-spots are radioactive materials released in the accident at the Fukushima Daiichi Nuclear Power Station fall with rain and immersed in earth and sand, repeated drying and deposition, resulting in a relatively high radioactivity concentration. Generally, it is said that under gutters and road gutters are likely to become microspots.

[Progress of response, etc.]
After the Fukushima Daiichi Nuclear Power Plant accident in March 2011, it was found that there were places in the city where dust was accumulated and the radiation dose was higher than that of the surrounding area. Was.

In response to this, even in nursery schools, etc., in September 2011, places where the radiation dose may be higher than the surrounding area, such as under gutters, ditches and gutters on the veranda, gutters on the veranda, rainwater basins and sewage basins. We removed accumulations such as soil, moss, dead leaves, etc. just in case, put them in a plastic bag, sealed, and temporarily stored in the park.

After that, based on the policy prepared by the City Radiation Control Department with reference to the national guidelines and the situation in other cities, 0.23 microsieverts per hour at a point of 50 cm above the ground and 0.59 per hour at a point of 1 cm above the ground We have set a guideline for dealing with 0.59 microsievert.

As a result of measuring the radiation dose of the accumulated materials stored at each facility from February to March 2012, most facilities measured results were less than the standard of response, and were originally excluded from removal. It was an accumulation that did not.

In addition, radiation doses were measured every month in principle at places where there was a possibility of micro spots at each facility from summer 2012 to March 2014, but it was below the standard value of the response .

After that, after September 2014, if the measurement results of the removed accumulated items are less than the standard for Motoichi, we carry out burial treatment to refill the facility premises in principle. At the time of burial, the spatial radiation dose after the burial of the buried site is also measured, and it is confirmed that it is below the guideline for response.

In addition, among nursery schools that exceeded the standard for measurements between February and March 2012, those facilities that exceeded the standard for re-measurement as of June 2016 were transferred to a storage in Hokubu Sludge Treatment Plant, Tsurumi Ward.
　June 2019 Child and Youth Bureau

~ Frequently Asked Questions ~

Q I saw reports that radiation contaminated soil is buried in nursery schools. Is it true?

A In Yokohama City, in response to the effects of radioactive materials associated with the accident at the Fukushima Daiichi Nuclear Power Station, in nursery schools, etc., accumulates such as soil, sand, dead leaves, etc. in places that may become microspots. I removed it.
We measure radiation dose about these and, about result is less than standard standard value of Yokohama-shi correspondence, and, about thing which we confirmed that it was safe, buried processing in each facility site.
In addition, about accumulation thing which radiation dose exceeds standard standard value of Motoichi correspondence, we move to another place (Hokubu Sludge Treatment Plant) and store.

Q Would you like to move buried soil from the nursery school?

A About accumulation that radiation dose exceeds standard standard value of Motoichi correspondence, we move to another place (Hokubu Sludge Treatment Plant) and store.
　The agglomeration buried in the facility premises collects the soil of places that may become micro spots in case, and as a result of the measurement, it is less than the standard value of the city's standard value and is safe There is no plan to move because it has been confirmed.

[Basic information on radiation]

●Ministry of the Environment's Information Site for the Treatment of Radioactive Substances
You can see basic information on radiation, such as "Differences in radioactive materials, radioactivity, and radiation" and "What is becquerel and sievert".

(Homepage of the Ministry of the Environment)
http://shiteihaiki.env.go.jp/radiological_contaminated_waste/basic_knowledge/how_different.html (external site)

●You can see the current air dose rates nationwide on the Nuclear Regulation Authority's radiation monitoring information portal site.

(Homepage of Nuclear Regulatory Commission)
https://radioactivity.nsr.go.jp/map/en/ (external site)