Re: [tlug] How much of radiations measured in Central Tokyo?

["Stephen J. Turnbull" <stephenjturnbull@example.com>]

On Tue, Mar 15, 2011 at 10:22 PM, Michael Bitker <mbitker@example.com> wrote:
> On Tue, Mar 15, 2011 at 10:12 PM, Stephen J. Turnbull <stephen@example.com>
> wrote:
>>
>> I'm not sure what cpm (counts per minute) means in terms of sieverts.
>> Probably very little, as what matters for sieverts is the amount of energy
>> delivered, not the number of events.
>
> The wakwak geiger counter is calibrated to 100 cpm = 1 microSv.

Well ... according to the manufacturer's data sheets, it's calibrated to
100cpm = 1 microgray (not sievert, although IIUC that difference doesn't
matter for the kinds of radiation (gamma and beta) that are probably
relevant here), assuming the radiation is gamma rays from cobalt60 or
something (presumably both beta and gamma rays) from cesium137, and
have enough radiation to generate 2.5 counts per *second*.  IOW, there's
a lot of assumptions, and even at the spike of 80/min, you're still well
outside of recommended operating range.

ISTR cesium137 being mentioned as one of the possible nuclides being
leaked, so that calibration *may* be correct for this application.  But I don't
know if it would be the same for, say, iodine, which is also mentioned as
one of the leaked elements.