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0 pointstrhway5mo ago0 comments

My experience so far has been that when people say "full stop", it usually makes a lot of sense to fact-check further what they said. In this case the notice says his hair is 300 counts per minute after decontamination. The typical background is under 100.

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iterance5mo ago

Your fact checking was not successful: there is no typical background expressed in counts. Background count rates vary globally by significant amounts, but importantly, they vary by device. Some devices may get a measly 10-20 counts per minute in a background, next to another device that could get 500. It also matters what kind of radiation the device is configured to detect.

At any rate 300 is widely recognizable as not an alarming value for a typical contamination detector in a typical configuration, but the report is likely slightly deficient because it does not specify how the measurement was taken. However, even if we accept 100 as the background CPM value, 300 on 100 does not represent significant contamination in a typical environment (but does imply some occurred).

trhwayOP5mo ago

>but importantly, they vary by device.

Of course it varies for "civilian" devices from EBay.

They put that count into NRC report. It means that it has pretty specific calibrated meaning for that regulated environment.

>However, even if we accept 100 as the background CPM value, 300 on 100 does not represent significant contamination in a typical environment (but does imply some occurred).

report mentions 300 clearly as something above normal, whatever normal is there. And that is after decontamination. Clearly the source of contamination - the pool - is much higher than 300.

lazide5mo ago

CPM has no calibrated amount by itself.

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