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April 25, 17:00, 2011

Measurement result of airborne nuclide and air radiation level in Tsukuba area: seventh report

KEK, in conjunction with National Institute for Environmental Study (NIES) have been conducting the measurement to assess the airborne nuclide and air radiation level in Tsukuba area since 15 March. In this report, the results of measurements, conducted between 11 April and 21 April, are shown in the chart below. Please refer to the previous reports for the measurement results before 11 April.

KEK will have another measurement hereafter, and will report the result accordingly.

Measurement condition:

  1. Measurement point: In the premise of NIES (16-2 Onogawa, Tsukuba-City, Ibaraki)
  2. Air sampling instrument: High-volume air sampler, with the capability of filling 600 litters of air per minutes . Each measurement took two days for the sampling.
  3. Filter used: Collected by a quartz fiber filter and doubly stacked activated carbon filters 

Filter analysis instrument: KEK’s High Resolution Ge detector

Measurement result:

Te-132 was detected in the sample taken during the period of 9-11 April, and was not detected after 11 April. There were some precipitation during 17-19 April, and the measured concentration increase slightly from the revious period.

Chart1 Result of 21th measurement: Detected nuclide and its concentration (Bq/cm3)

Measurement period: 11 April, 2011 10:54 - 13 April, 2011 10:45
Air collected:1723 cubic meter

graph
NuclideCONC (Bq/cm3)
Iodine1311.9×10-8
Tellurium132no detection
Caesium1349.2×10-9
Caesium136no detection
Caesium1378.5×10-9
Tellurium129mno detection
Iodine133no detection
Technetium99mno detection

Chart2 Result of 22th measurement: Detected nuclide and its concentration (Bq/cm3)

Measurement period: 13 April, 2011 10:53 - 15 April, 2011 10:53
Air collected:1728 cubic meter

graph
NuclideCONC (Bq/cm3)
Iodine1312.8×10-8
Tellurium132no detection
Caesium1346.8×10-9
Caesium136no detection
Caesium1375.8×10-9
Tellurium129mno detection
Iodine133no detection
Technetium99mno detection

Chart3 Result of 23th measurement: Detected nuclide and its concentration (Bq/cm3)

Measurement period: 15 April, 2011 11:25 - 17 April, 2011 11:05
Air collected:1715 cubic meter

graph
NuclideCONC (Bq/cm3)
Iodine1316.1×10-9
Tellurium132no detection
Caesium1341.1×10-9
Caesium136no detection
Caesium1371.1×10-9
Tellurium129mno detection
Iodine133no detection
Technetium99mno detection

Chart4 Result of 24th measurement: Detected nuclide and its concentration (Bq/cm3)

Measurement period: 17 April, 2011 11:11 - 19 April, 2011 11:11
Air collected:1728 cubic meter

graph
NuclideCONC (Bq/cm3)
Iodine1311.9×10-7
Tellurium132no detection
Caesium1341.3×10-7
Caesium1362.4×10-9
Caesium1371.2×10-7
Tellurium129m2.3×10-8
Iodine133no detection
Technetium99mno detection

Chart5 Result of 25th measurement: Detected nuclide and its concentration (Bq/cm3)

Measurement period: 19 April, 2011 11:21 - 21 April, 2011 11:21
Air collected:1728 cubic meter

graph
NuclideCONC (Bq/cm3)
Iodine1313.6×10-8
Tellurium132no detection
Caesium1341.5×10-8
Caesium136no detection
Caesium1371.5×10-8
Tellurium129mno detection
Iodine133no detection
Technetium99mno detection

Concentration of the airborne nuclide since 28 March (Bq/cm3)

graph


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