Results of Local Measurements of Ambient Radiation Levels at Municipal Elementary and Junior High Schools (Updated October 19, 2020)

The measurement results up to now are stable and below the Ministry of the Environment's standard value (0.23 microsieverts per hour). Therefore, based on the policy for measuring ambient radiation levels in the city, measurements of ambient radiation levels at municipal Elementary and Junior High Schools have been suspended since fiscal year 2017.
In addition, measurements of rainwater drains at Shiroyama Elementary School and Inagi Dai 5 Junior High School were conducted once a year (in August). However, starting from the fiscal year 2021, we will suspend measurements of ambient radiation levels in the city due to reasons such as stable values within the standard range and the fact that the radiation monitoring post in Shinjuku, which was established before the Great East Japan Earthquake, has shown values that have decreased to pre-earthquake levels. However, if any concerns arise, we will immediately resume measurements.

Measurement Results (Conducted in Fiscal Year 2016)

Inagi Dai 1 Elementary School (Measurement Date: February 14, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Rainwater Drain (East Side of School Building)	0.071
Drainage ditch (East side of the school building)	0.063
Downspout (West side of the pool)	0.069
Sandpit (North side of the pool)	0.037
Leaf Collection (North Side of the School Building)	0.056

Inagi Dai 2 Elementary School (Measurement Date: February 13, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Downspout (West side of the school building)	0.136
Leaf Collection (South Side of Gymnasium)	0.045
Sandpit (North side of the school building)	0.031
Rainwater Drain (East Side of School Building)	0.052
Gutter (East side of the school building)	0.069

Inagi Dai 3 Elementary School (Measurement Date: February 13, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Sewage Manhole (South Side of School Building)	0.054
Drainage ditch (East side of the pool)	0.065
Sandpit (East side of the gymnasium)	0.037
Downspout (East side of the gymnasium)	0.067
Leaf Collection (East Side of Gymnasium)	0.056

Inagi Dai 4 Elementary School (Measurement Date: February 15, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Rainwater Drain (South Side of School Building)	0.054
Others (Main Gate)	0.043
Gutter (West side of the pool)	0.059
Sandpit (North side of the pool)	0.053
Downspout (North side of the school building)	0.094

Inagi Dai 6 Elementary School (Measurement Date: February 13, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Sandpit (East side of the schoolyard)	0.043
Gutter (West side of the pool)	0.058
Downspout (South side of the school building)	0.063
Rainwater Drain (South Side of School Building)	0.062
Leaf Collection (North Side of Gymnasium)	0.073

Inagi Dai 7 Elementary School (Measurement Date: February 14, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Rainwater Drain (East Side of Gymnasium)	0.060
Leaf Collection (East Side of the School Building)	0.046
Downspout (East side of the disaster prevention warehouse)	0.060
Others (Rice Field on the East Side of the School Building)	0.036
Sandpit (West side of the school building)	0.044
Gutter (North side of the schoolyard)	0.055

Koyodai Elementary School (Measurement Date: February 13, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Downspout (West side of the pool)	0.087
Sandpit (South side of the schoolyard)	0.040
Leaf Collection (West Side of the Schoolyard)	0.069
Drainage ditch (south side of the school building)	0.047
Rainwater Drain (West Side of School Building)	0.051

Shiroyama Elementary School (Measurement Date: February 15, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Downspout (North side of the school building)	0.094
Others (Pond)	0.086
Drainage ditch (south side of the school building)	0.074
Leaf Collection (Field South of the School Building)	0.086
Sandpit (South side of the schoolyard)	0.045
Rainwater Drain (West Side of the Schoolyard)	0.056

Nagamine Elementary School (Measurement Date: February 16, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Leaf Collection (South Side of the Schoolyard)	0.039
Drainage ditch (south side of the gymnasium)	0.055
Rainwater Drain (East Side of Pool)	0.069
Downspout (South side of the school building)	0.081
Sandbox (East side of the school building)	0.044

Wakabadai Elementary School (Measurement Date: February 14, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Sandpit (West side of the schoolyard)	0.037
Gutter (West side of the schoolyard)	0.046
Leaf Collection (West Side of the School Building)	0.095
Downspout (East side of the school building)	0.085
Rainwater Drain (East Side of Pool)	0.049
Others (South Side Planting)	0.058

Hirao Elementary School (Measurement Date: February 21, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Leaf Collection (South Side of the School Building)	0.061
Downspout (East side of the school building)	0.056
Gutter (North side of the schoolyard)	0.052
Rainwater Drain (North Side of the Schoolyard)	0.060
Sandpit (North side of the pool)	0.040

Minamiyama Elementary School (Measurement Date: February 21, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Sandbox (South side of the pool)	0.041
Others (West Corner of the Gymnasium)	0.073
Rainwater Drain (North Side of Gymnasium)	0.054
Downspout (North side of the school building)	0.091
Drainage ditch (East side of the gymnasium, center of the school building)	0.061
Leaf Collection (North Side of Main Gate)	0.034

Inagi Dai 1 Junior High School (Measurement Date: February 16, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Sandpit (South side of the schoolyard)	0.036
Leaf Collection (South Side of the Schoolyard)	0.059
Downspout (South side of the gymnasium)	0.182
Rainwater Drain (South Side of School Building)	0.054
Drainage ditch (south side of the school building)	0.152

Inagi Dai 2 Junior High School (Measurement Date: February 13, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Drainage ditch (in front of the main gate)	0.061
Sandpit (East side of the schoolyard)	0.037
Downspout (East side of the gymnasium)	0.071
Rainwater Drain (East Side of Gymnasium)	0.062
Leaf Collection (East Side of the Pool)	0.068

Inagi Dai 3 Junior High School (Measurement Date: February 21, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Rainwater Drain (South Side of Gymnasium)	0.048
Downspout (South side of the gymnasium)	0.084
Sandpit (West side of the school building)	0.062
Leaf Collection (West Side of the Schoolyard)	0.058
Drainage ditch (south side of the school building)	0.064

Inagi Dai 4 Junior High School (Measurement Date: February 15, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Leaf Collection (West Side of the Schoolyard)	0.067
Gutter (South side of the schoolyard)	0.076
Sandpit (East side of the schoolyard)	0.035
Rainwater Drain (West Side of Gymnasium)	0.088
Downspout (West side of the gymnasium)	0.127
Others (West Side Parking Lot)	0.094

Inagi Dai 5 Junior High School (Measurement Date: February 15, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Downspout (South side of the school building)	0.078
Others (Field)	0.076
Leaf Collection (North Side of the Schoolyard)	0.056
Gutter (West side of the schoolyard)	0.070
Rainwater Drain (East Side of Gymnasium)	0.071
Sandpit (South side of the schoolyard)	0.050

Inagi Dai 6 Junior High School (Measurement Date: February 14, Weather: Clear)

Measurement Location	Measurement Values (Unit: microsieverts per hour) 1 centimeter above ground
Rainwater Drain (South Side of the Schoolyard)	0.088
Leaf Collection (South Side of the Pool)	0.059
Sandpit (South side of the schoolyard)	0.039
Drainage ditch (north side of the school building)	0.082
Others (Flower bed on the south side of the school building)	0.087

Description

When converted annually, 0.23 microsieverts per hour amounts to 0.99864 millisieverts, which is below the standard value for radiation exposure for the general public during normal times (less than 1 millisievert per year, excluding natural background radiation) as recommended by the International Commission on Radiological Protection (ICRP). Therefore, this value is used as the city's judgment criterion.
According to the Ministry of the Environment's "Decontamination Guidelines," if the radiation level at a depth of 1 meter below the surface is below 0.23 microsieverts per hour, no further action is required. However, our city takes a more cautious approach and makes decisions based on measurement results taken at the closest location to the target area (1 centimeter below the surface).

• Local Radiation Measurement Results of Public Facilities in the City

Measurement Overview

Measurer

City Employee

Measuring Equipment

PA-1000

Measurement Method

Average of 5 repeated measurements every 60 seconds (PA-1000)

Past Measurement Results

• Public Elementary and Junior High Schools (PDF 215.4KB)

About Cleaning and Other Services

Shiroyama Elementary School

As a result of measurements taken at the rainwater drain on the schoolyard side, values exceeding 0.23 microsieverts per hour were recorded. Therefore, we conducted work to reduce radiation levels through cleaning. We removed the soil that had accumulated in the rainwater drain, placed the removed soil into sandbags, covered them with double plastic bags for sealing, and then dug a hole 50 centimeters deep outside the north side of the schoolyard's protective fence, filled it in, and covered it with soil.
The radiation levels in the rainwater drainage after cleaning were confirmed to be below the standard value, and the radiation levels outside the north side of the schoolyard's protective fence, where soil was buried, were also confirmed to be below the standard value (refer to "Past Measurement Results" for the figures).

Inagi City Inagi Dai 5 Junior High School

1. As a result of measurements taken under the gymnasium's rain gutter, values exceeding 0.23 microsieverts per hour were recorded, prompting us to carry out radiation reduction work through cleaning. We removed the soil from the ditch located under the rain gutter, extending 1.5 meters before and after the gutter, placed the removed soil into sandbags, and then double-wrapped them in plastic bags for sealing. After that, we dug a 70-centimeter deep hole southwest of the gymnasium, buried the soil, and covered it up. The radiation levels under the rain gutter after cleaning were confirmed to be below the standard value, and the radiation levels in the area where the soil was buried southwest of the gymnasium were also confirmed to be below the standard value (refer to "Past Measurement Results" for the values).
2. As a result of measurements taken under the school building's rain gutter, values exceeding 0.23 microsieverts per hour were recorded, prompting us to carry out radiation reduction work through cleaning. We removed the soil from the ditch under the rain gutter, placed the removed soil into sandbags, covered them with double plastic bags for sealing, and then dug a 70-centimeter deep hole southwest of the gymnasium to bury the soil, followed by covering it with earth. Additionally, we cleaned the walls near the rain gutter, the asphalt under the rain gutter, and the inside of the rain gutter using a high-pressure washer. After cleaning, the radiation level under the rain gutter was confirmed to be below the standard value, and the radiation level in the area where the soil was buried southwest of the gymnasium was also confirmed to be below the standard value (refer to "Past Measurement Results" for the values).

Observation

Regular measurements are conducted at locations where cleaning and other activities have been carried out, and the progress is being monitored. The results of the progress monitoring measurements are as follows.

Measurement Date	Shiroyama Elementary School (Rainwater Drain)	Shiroyama Elementary School (Sandbag Burial Location)	Inagi Dai 5 Junior High School (Under the gymnasium rain gutter)	Inagi Dai 5 Junior High School (School Building Rain Gutter Downspout)	Inagi Dai 5 Junior High School (Sandbag Burial Location)
May 16, 2012	0.112	0.086	0.119	0.207	0.101
August 13 and 16, 2012	0.103	0.068	0.114	0.131	0.104
November 14, 2012	0.1	0.081	0.109	0.128	0.094
February 14, 2013	0.094	0.082	0.104	0.137	0.114
May 23, 2013	0.09	0.077	0.093	0.109	0.124
August 15, 2013	0.089	0.065	0.103	0.111	0.085
November 19, 2013	0.082	0.057	0.093	0.12	0.089
February 25 and 28, 2014	0.083	0.073	0.099	0.118	0.095
May 27, 2014	0.086	0.074	0.091	0.112	0.081
August 18, 2014	0.08	0.058	0.098	0.108	0.083
November 21, 2014	0.078	0.055	0.095	0.109	0.08
February 10, 2015	0.079	0.057	0.092	0.114	0.083
May 27, 2015	0.073	0.052	0.074	0.102	0.084
August 25, 2015	0.072	0.055	0.096	0.099	0.075
November 19, 2015	0.076	0.05	0.084	0.09	0.077
February 15 and 29, 2016	0.08	0.057	0.088	0.111	0.087
May 25, 2016	0.072	0.054	0.079	0.096	0.085
August 18, 2016	0.068	0.044	0.073	0.095	0.085
November 28, 2016	0.071	0.058	0.096	0.073	0.092
February 15, 2017	0.066	0.058	0.083	0.089	0.085
August 22, 2017	0.064	0.056	0.077	0.091	0.081
August 29, 2018	0.063	0.047	0.071	0.074	0.085
August 28, 2019	0.058	0.047	0.07	0.088	0.082
August 28, 2020	0.043	0.044	0.074	0.065	0.083

Measurement Overview

Measurer

City Employee

Measuring Equipment

PA-1000

Measurement Method

Average of 5 repeated measurements every 60 seconds (PA-1000)

Measurement Values

Unit: MicroSieverts per hour (1 centimeter above the ground)