Air Monitoring at UNLV


for Radionuclides Released from the Fukushima Accident

Preliminary Results


As a training exercise for students in our programs and to provide information to the general public, the UNLV Health Physics department has set up a high-volume air sampler on the roof of the Bigelow Health Sciences building in an attempt to measure radionuclides released from the Fukushima Daiichi accident in Japan:

Sampling
Period
Air Volume
Sampled
(L)
I-131
Activity
(pCi/L)
Fraction of
NRC Release
Limit
(%)
Cs-137
Activity
(pCi/L)
Fraction of
NRC Release
Limit
(%)
NAD = No activity detected
* Denotes a measurement with only an air filter without a charcoal cartridge
3/15 15:11 –
3/15 21:00
34235 NAD NAD
3/15 21:07 –
3/16 9:05
71188 NAD NAD
3/16 9:07 –
3/17 9:00
139772 1.7E-05* 0.0085 NAD
3/17 9:04 –
3/17 15:08
36925 1.2E-04* 0.058 NAD
3/17 15:22 –
3/18 15:18
122527 5.6E-04 0.28 1.5E-05 0.0075
3/18 15:19 –
3/19 15:20
125472 1.4E-03 0.71 7.1E-05 0.036
3/19 15:26 –
3/20 15:26
123744 9.3E-04 0.47 2.6E-05 0.013
3/20 15:30 –
3/21 15:27
112446 9.3E-04 0.47 2.0E-05 0.0098
3/21 15:34 –
3/22 15:38
123461 5.6E-04 0.28 NAD
3/22 15:41 –
3/23 15:38
121054 3.9E-04 0.20 NAD
3/23 16:13 –
3/24 16:04
94182 9.1E-04 0.46 3.9E-05 0.019
3/24 16:07 –
3/25 16:04
104461 1.2E-03 0.57 1.27E-04 0.064
3/25 16:06 –
3/26 16:11
109161 4.2E-04 0.21 1.64E-05 0.0082
3/26 16:16 –
3/27 16:34
107349 2.4E-04 0.12 NAD
3/27 16:38 –
3/28 18:38
111313 1.8E-04 0.088 NAD
3/28 18:42 –
3/29 07:30
56634 1.7E-04 0.085 NAD
3/29 18:52 –
3/30 18:48
106386 1.1E-04 0.054 NAD
3/30 18:50 –
3/31 18:43
106386 2.7E-05 0.013 NAD
3/31 18:50 –
4/1 19:12
106754 1.7E-05 0.0087 NAD
4/1 19:16 –
4/2 19:10
104829 1.4E-05 0.0070 NAD
4/2 19:15 –
4/3 19:42
111143 2.9E-05 0.014 NAD
4/3 19:46 –
4/5 9:04
173072 5.9E-05 0.029 NAD
4/5 9:09 –
4/6 9:03
110634 3.2E-05 0.016 NAD
4/6 9:07 –
4/7 9:26
110804 2.1E-05 0.010 NAD
4/7 9:30 –
4/7 12:09
12060 NAD NAD


The data presented here will be updated as samples are analyzed. Usually, we were collecting air over a 24 hour period using a particulate filter and a cartridge filled with activated charcoal. The samples were then removed for analysis by gamma spectroscopy and measured for 24 hours on a HPGE detector. Due to weather conditions and wind-induced damage to the air sampler the sampling was stopped on April 7, 2011

What do these numbers mean?

In the data table, we are presenting the measured concentration of these radionuclides in the air, in terms of picocuries (pCi) per liter of air sampled. For comparison, we are also showing the effluent limit proposed by the Nuclear Regulatory Commission (10CFR20). The effluent limit corresponds to an annual dose of 500 uSv, which is approximated 10% of the annual exposure due to background radiation. This means that IF you were to breathe air at the effluent limit for an entire year, your radiation exposure would be increased by approximately 10%, or about the radiation that would be received from a mammogram or by flying in a commercial airplane for 100 hours a year.

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