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KEK | HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

March 17, 17:00, 2011

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

KEK, in conjunction with National Institute for Environmental Study (NIES) have conducted the measurement to assess the airborne nuclide and air radiation level in Tsukuba area between 15 and 16 March as shown in the chart below.

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
The environment radiation level during the measurement period: Between 0.1 and 0.3 microsievelts per hour (μSv/h)
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 and no other nuclide has been found on the filter.

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

Measurement period:15 March, 2011 14:39?17:34
Air collected:105 cubic meter

Nuclide	Iodine131	Tellurium132^※
Quartz filter	2.1×10^-5	2.0×10^-5
Activated carbon filter	8.7×10^-6	4.1×10^-8
Sum	3.0×10^-5	2.0×10^-5

Chart 2 Result of second measurement: Detected nuclide and its concentration (Bq/cm³)

Measurement period：15 March, 2011 17：48?16 March,2011 8:48
Air collected：540 cubic meter

Nuclide	Iodine131	Tellurium132^※
Quartz filter	1.5×10^-5	4.9×10^-6
Activated carbon filter	5.8×10^-6	5.8×10^-9
Sum	2.1×10^-5	4.9×10^-6

* Iodine-132 is a daughter nuclide of the Tellurium 132, and included in this measurement.

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