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KEK | HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION
May 13, 17:00, 2011
Measurement result of airborne nuclide and air radiation level in Tsukuba area: eighth 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 21 April and 9 May, are shown in the chart below. Please refer to the previous reports for the measurement results before 21 April.
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 . Each measurement took two days for the sampling.
- 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:
During the measurement period between 1 and 3 May, large amount of sand was blown in strong wind, but the level of radiation was observed low. From 3 to 5 May, the level of radiation showed slight increase due to the rainfall during this period. The nuclides Cs-137 and Cs-134 deposited on the ground appeared not to be stir up by wind. The radiation level of the period from 7 to 9 May was the lowest ever since KEK started monitoring.
Chart1 Results from 25th to 29th measurements: Detected nuclide and its concentration (Bq/cm3)
| 26th | 27th | 28th | 29th | |
| Measurement period | 21 April 13:45 - 23 April 11:28 | 23 April 11:37 - 25 April 11:05 | 25 April 11:13 - 27 April 11:13 | 27 April 11:45 - 29 April 10:51 |
| Air collected | 1,647 m3 | 1,708 m3 | 1,728 m3 | 1,660 m3 |
| Nuclide | CONC (Bq/cm3) | CONC (Bq/cm3) | CONC (Bq/cm3) | CONC (Bq/cm3) |
| Iodine131 | 3.2×10-8 | 5.5×10-9 | 2.3×10-9 | 8.3×10-10 |
| Tellurium132 | no detection | no detection | no detection | no detection |
| Caesium134 | 3.6×10-8 | 3.6×10-9 | 9.5×10-10 | 8.8×10-10 |
| Caesium136 | 6.6×10-10 | no detection | no detection | no detection |
| Caesium137 | 3.4×10-8 | 3.4×10-9 | 7.0×10-10 | 7.8×10-10 |
| Tellurium129m | no detection | no detection | no detection | no detection |
Chart2 Results from 30th to 33rd measurements: Detected nuclide and its concentration (Bq/cm3)
| 30th | 31th | 32th | 33th | |
| Measurement period | 29 April 10:58 - 1 May 10:58 | 1 May 11:03 - 3 May 11:03 | 3 May 11:43 - 5 May 11:41 | 5 May 11:48 - 7 May 11:48 |
| Air collected | 1,728 m3 | 1,728 m3 | 1,726 m3 | 1,728 m3 |
| Nuclide | CONC (Bq/cm3) | CONC (Bq/cm3) | CONC (Bq/cm3) | CONC (Bq/cm3) |
| Iodine131 | 1.7×10-9 | 8.6×10-10 | 1.2×10-8 | 4.7×10-9 |
| Tellurium132 | no detection | no detection | no detection | no detection |
| Caesium134 | 2.1×10-9 | 8.4×10-10 | 2.6×10-8 | 6.5×10-9 |
| Caesium136 | no detection | no detection | 2.9×10-10 | no detection |
| Caesium137 | 2.1×10-9 | 7.7×10-10 | 2.6×10-8 | 6.3×10-9 |
| Tellurium129m | no detection | no detection | no detection | no detection |
Chart3 Result of 34th measurement: Detected nuclide and its concentration (Bq/cm3)
| 34th | |
| Measurement period | 7 May 12:39 - 9 May 11:43 |
| Air collected | 1,694 m3 |
| Nuclide | CONC (Bq/cm3) |
| Iodine131 | 4.1×10-10 |
| Tellurium132 | no detection |
| Caesium134 | no detection |
| Caesium136 | no detection |
| Caesium137 | no detection |
| Tellurium129m | no detection |
Concentration of the airborne nuclide since 28 March (Bq/cm3)
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