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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: fourth 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 9th and 10th measurements, conducted between 23 and 25 March, are shown in the chart below. Please refer to the third report for the measurement results before 23 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:
9th measurement: Collected by a quartz fiber filter and doubly stacked activated carbon filters
10th measurement: Collected by a glass fiber fiber filter and doubly stacked activated carbon filters
- The performance to collect nuclide with the quartz filter and the glass fiber filter are considered to be in a same level.
- Filter analysis instrument: KEK’s High Resolution Ge detector
Measurement result:
Iodine-131 (half-life of 8.02 days) remains a major nuclide detected in the air. Increased level of the nuclide between 20 - 22 March, reported in the third report, has been decreased.
Chart1 Result of 9th measurement: Detected nuclide and its concentration (Bq/cm3)
Measurement period:23 March, 2011 11:20 - 24 March,2011 11:02
Air collected:853 cubic meter
| Nuclide | CONC (Bq/cm3) |
| Iodine131 | 1.9×10-6 |
| Tellurium132 | 9.7×10-9 |
| Caesium134 | 1.7×10-8 |
| Caesium136 | 2.1×10-9 |
| Caesium137 | 1.7×10-8 |
| Tellurium129m | no detection |
| Iodine133 | no detection |
| Technetium99m*2 | 4.5×10-9 |
Chart2 Result of 10th measurement: Detected nuclide and its concentration (Bq/cm3)
Measurement period:24 March, 2011 11:15 - 25 March,2011 10:43
Air collected:845 cubic meter
| Nuclide | CONC (Bq/cm3) |
| Iodine131 | 7.3×10-7 |
| Tellurium132 | 3.2×10-9 |
| Caesium134 | 5.0×10-9 |
| Caesium136 | no detection |
| Caesium137 | 5.2×10-9 |
| Tellurium129m | no detection |
| Iodine133 | no detection |
| Technetium99m | no detection |
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