Results of measurement at municipal nursery schools (Kohoku Ward)

This is due to the confirmation of "micro spots" around rainwater basins in road gutters in Kohoku Ward

Measurement results of radiation dose at municipal nursery schools in Kohoku Ward

Radiation doses at higher levels in the vicinity of road gutters in Kohoku Ward were confirmed, and radiation doses were urgently measured at locations where there could be a "microspots" (where higher radiation doses were measured) atKohoku Ward, which are considered to be susceptible to radiation.

(1)　Date of measurement

From 9:30 am on Sunday, September 18, 2011

(2)　Number of facilities to be implemented and number of measurement locations

95 municipal nursery schools in Kohoku Ward (10 to 22 each garden)

(3)　Measurement location

Among the places where children may approach the facility, places that are likely to become "micro spots" are categorized, and measurement locations are selected. In addition, we measure the nursery room and the center of the garden to refer to the evaluation of the measured values.

(1)　The lower part of the vertical gutter (rain gutter) (excluding those directly connected to sewage) and its surroundings
(2)　Gutter and its surroundings (in the gutter where the upper part is open, the gutter cover gap)
(3)　Rainwater basins and sewage basins, surrounding areas
(4)　Dead leaves accumulation area (places that fall naturally under trees and hedges, places that have been collected by cleaning, places that have been naturally gathered due to wind and rain, etc.)
(5)　Home garden
(6)　Surface of turf, moss
(7)　Places that slide down from slides (playground equipment, evacuation)
(8)　Rooftop and terrace where people can enter and exit (a place where rainwater, dust, etc. accumulate)
(9)　Sandbox
(10)　Pool
(11)　Outdoor hand-washing area
(12)　The center of the garden
(13)　Nursery room (1 room on the 1st floor)

(4)　Measurement equipment

NaI (TI) scintillation detector TCS-172B (manufactured by Hitachi Aloka Medical)

(5)　Measurement contents

Space γ (gamma) dose of 1cm, 5cm, and 50cm on the surface before and after cleaning.

(6)　Measurement results

Measurements were performed mainly in places where children could approach and were likely to become "micro spots", but all were lower than 0.59 μSv / h, which is a measure for remeasurement.

In addition, values exceeding 0.59 μSv / h are measured at places where sand was deposited on a rooftop where people do not enter on a daily basis (one place).

List of measurement results (PDF: 73KB)

Regardless of the results of the measurement, in order to grasp the effects of cleaning at municipal nursery schools that take care of infants who are susceptible to radiation as soon as possible and to understand the effects of cleaning, `` micro spots '' on the premises We carried out cleaning where there could be.

Accumulations such as soil, stone, dead leaves, moss, and dust were removed at the relevant location. In addition, the removed items are sealed in double plastic bags, covered with blue sheets, etc. to prevent scattering, and temporarily stored in a place where children do not approach.