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Joined: Thu Oct 31, 2013 10:24 am
Posts: 70
So Harland or King Cobra or whomever can answer...

In relation to netc getting a direct feed from the EPA and then posting those feeds to netc maps, how does netc use CPM (counts per minute or clicks per minute) when the EPA measures gamma count rateS each hour? Is there or should there be some type of mathematical equation in order to convert EPA's hourly count to netc's CPM.

It seems to me that the CPM on netc are overly stated or exaggerated? If CPM averages on netc were truly over 100 CPM there should be alarms going off and quite a bit of concern for human health and safety.

Am I missing something? Anyone have a logical explanation for this in layman's terms?

"This data comes to the laboratory as a "gamma count rate," which shows how many gamma rays the monitor detects each hour."

Further info...

Data from each fixed RadNet monitor are transmitted to EPA’s National
Air and Radiation Environmental Laboratory hourly. These data include
the gamma radiation measured during that hour.
The data are screened
against pre-set values for each monitor to identify unusual readings,
particularly elevated radiation levels. In order to increase sensitivity
for screening the spectrum for small increases in gamma radiation, EPA
divides the gamma radiation measurement data into nine different gamma
energy ranges
that collectively cover the energy spectrum where
essentially all of the nuclides of concern will be detected by our

Fri Apr 25, 2014 12:17 pm
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Joined: Mon Jan 28, 2013 7:40 pm
Posts: 2887
Location: Illinois
ifferent geiger counter models return different CPM readings due to the sensitivity of the equipment. The same amout of radiation will give different CPM readings between this equipment. The EPA NETC station 5: are not geiger counters but rather sintilation counters that have an even higher sensitivity than even the best geiger counters.

100 CPM on the EPA NETC 5: stations is not an alarming level, in fact that is quite low for that equipment. We need to remember that the EPA gamma stations on NETC are only listing one of the channels, number 5.

Now to see 100 CPM on the GMC-xxx models would be an alarming concern but still I wouldn't consider high enough to evacuate my house.

South Beloit, Illinois - GMC200 Outside on HEPA air purifier, ground level, facing West.

Fri Apr 25, 2014 12:56 pm
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