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KEK | HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION
March 28, 17:00, 2011
Measurement result of airborne nuclide and air radiation level in Tsukuba area: third 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 17 and 23 March, are shown in the chart below. Please refer to the third report for the measurement results before 17 March.
KEK will have another measurement hereafter, and will report the result accordingly.
Measurement condition:
- Measurement point: In the premise of NIES (16-2 Onogawa, Tsukuba-City, Ibaraki)
- Air sampling instrument: High-volume air sampler, with the capability of filling 600 litters of air per minutes.
- Filter used: Double filter with the quartz filter and activated carbon filter
- Filter analysis instrument: KEK’s High Resolution Ge detector
Measurement result:
Iodine-131 (half-life of 8.02 days), Tellurium-132 (half-life of 3.204 days), and Iodine-132, the daughter nuclide of Tellurium-132 (half-life of 2.295 hours) have detected.
Samples collected after the afternoon of 16 March, shows much lower value at concentrations one hundred times lower.
From 20 March to 22 March, there were increased concentrations of airborne nuclides, but on 23 March, they decreased.
Chart1 Result of fifth measurement: Detected nuclide and its concentration (Bq/cm3)
Measurement period:17 March, 2011 10:07-18 March,2011 10:07
Air collected:864 cubic meter
| Nuclide | CONC.(Bq/cm3) |
| Iodine131 | 3.2×10-7 |
| Tellurium132 | 3.8×10-9 |
| Caesium134 | 2.4×10-9 |
| Caesium136 | 3.5×10-10 |
| Caesium137 | 2.1×10-9 |
| Tellurium129m | no detection |
| Iodine133 | 3.8×10-9 |
| Technetium99m*1 | no detection |
Chart2 Result of sixth measurement: Detected nuclide and its concentration (Bq/cm3)
Measurement period:18 March, 2011 10：16-20 March,2011 9:55
Air collected:1715 cubic meter
| Nuclide | CONC.(Bq/cm3) |
| Iodine131 | 4.9×10-7 |
| Tellurium132 | 1.2×10-9 |
| Caesium134 | 1.1×10-9 |
| Caesium136 | no detection |
| Caesium137 | 1.1×10-9 |
| Tellurium129m | no detection |
| Iodine133 | 1.2×10-9 |
| Technetium99m*1 | no detection |
Chart3 Result of seventh measurement: Detected nuclide and its concentration (Bq/cm3)
Measurement period:20 March, 2011 10：00-22 March,2011 9:54
Air collected:1724 cubic meter
| Nuclide | CONC.(Bq/cm3) |
| Iodine131 | 2.3×10-5 |
| Tellurium132 | 4.6×10-6 |
| Caesium134 | 7.3×10-6 |
| Caesium136 | 8.7×10-7 |
| Caesium137 | 7.0×10-6 |
| Tellurium129m | 3.2×10-6 |
| Iodine133 | 7.2×10-9 |
| Technetium99m*1 | 4.6×10-7 |
Chart4 Result of eightth measurement: Detected nuclide and its concentration (Bq/cm3)
Measurement period:22 March, 2011 10：00-23 March,2011 11:10
Air collected:906 cubic meter
| Nuclide | CONC.(Bq/cm3) |
| Iodine131 | 9.6×10-6 |
| Tellurium132 | 5.7×10-7 |
| Caesium134 | 1.2×10-7 |
| Caesium136 | 1.1×10-8 |
| Caesium137 | 1.2×10-7 |
| Tellurium129m | 4.9×10-7 |
| Iodine133 | no detection |
| Technetium99m*1 | 5.3×10-8 |
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