Funny how some samples can be detected at 17 CPM but then others say <50 (none detected, but 50 is the minimum we can detect today. Hmmm maybe the reading is 48)
Keep in mind, this is Tokyo, pretty far away from the nuclear plant meltdowns.
http://www.gesui.metro.tokyo.jp/oshi/infn0757e.htm
Keep in Mind the Half Lives
I-131 8 Days Beta Decay, mutation and death of cells even several mm away
10% Gamma, so can be seen with Gamma Camera
Cesium-134 2.065 Years Beta Decay, and 1.6MeV Gamma
Cesium-137 30 Years Strong Gamma
You just got to love the nuclear industry--
"The isotope I-131 is still occasionally used for purely diagnostic (i.e., imaging) work, due to its low expense compared to other iodine radioisotopes"
http://en.wikipedia.org/wiki/Iodine_131
The other important thing to know about I-131 is that the small and moderate exposures are what causes the cancers, and it is very effective at that. The large exposures just flat out kill the nearby cells, which in a sick way is "better" because then the cells are just dead, and they do not become cancerous.
Protection--Potassium Iodide (use during a known risk). 7000 times the amount needed for daily nutrition. Also from the Wikipedia article.
The most common method of treatment is to give potassium iodide to those at risk. The dosage for adults is 130 mg potassium iodide per day, given in one dose, or divided into portions of 65 mg twice a day. This is equivalent to 100 mg of iodide, and is about 7000 times bigger than the nutritional dose of iodide, which is 0.015 mg per day (150 micrograms per day). See potassium iodide for more information on prevention of radioiodine absorption by the thyroid during nuclear accident, or for nuclear medical reasons. The FDA-approved dosing of potassium iodide for this purpose are as follows: infants less than 1 month old, 16 mg; children 1 month to 3 years, 32 mg; children 3 years to 18 years, 65 mg; adults 130 mg.[18] However, some sources recommend alternative dosing regimens.[19]
First, the units of the report are Bq/kg not counts per minute (CPM)
ReplyDeleteSecond, when using a germanium detector your minimum detectable level is a function of the size of your sample and the amount of time you spend counting photons.
You can cut your minimum detectable amount in half by counting photons for four times as long.
You can cut your minimum detectable amount in half by doubling the size of your sample.
You don't always get to have as large a sample as you would like and there are only 24 hours in each day so you have to make a choice about testing many samples for a short period or one sample for a long period.