Minnesota nuke spilled 400k gallons of water containing radioactive tritium
phys.org
phys.org
> "We are well above the 20,000 picocuries per liter EPA standard," Clark said. In water directly below the plant, the picocurie-per-liter count was in the millions.
Let's say 10,000,000Ci/liter = 1E7Ci/L. From https://www.unitconverters.net/radiation-activity/picocurie-... that is 4E-7TBq/L, From https://www.osti.gov/servlets/purl/5337327 the conversion rate for tritium is 23Sv/TBq, so we have 92E-7Sv/L = 9uSv/L.
How bad is to drink a litter (quarter of gallon) of this water? From https://xkcd.com/radiation/ that is 90 bananas, 2 dental x-ray or 1/4 of a flight from NY to LA. It's not negligible, but you are not ded. Try to avoid that anyway, my calculation may be wrong.
The 400k gallons are approximately 150k liters that have the radiation of 13 millions of bananas (like 1.5 million kg, 3.5 million pounds).
The "banana equivalent dose" is an error that refuses to die. Based on tables that estimate the effect of various radioactive isotopes acting for 50 years, people ignoring physiology decided that the average K40 in a banana will produce 0.078 microsievert of damage (rounded to 0.1 because it's close enough for jazz and comics).
The reality is that, due to homoeostasis, the excess potassium you ingest is eliminated the next time you piss, so there's no accumulation inside the organism. Those 50 years become something like 12 hours and the radiation exposure is more in the ballpark of 0.00000213 microsievert.
But that value is now too small to use it in science fanboyism, isn't it?
https://www.epa.gov/sites/default/files/2015-05/documents/52... - page 156. That's where these people took the effective dose equivalent for K^40 from, but those values are for 50 years of exposure.
"For radioisotopes of elements that are under tight homeostatic control by the human body, the inhalation or ingestion risk coefficients given in this document may not be appropriate for application to some exposure scenarios. For example, the ingestion risk coefficient for ^(40)K would not be appropriate for application to ingestion of ^(40)K in conjunction with an elevated intake of natural potassium. This is because the biokinetic model for potassium used in this document represents the relatively slow removal of potassium (biological half-time of 30 d) that is estimated to occur for typical intakes of potassium, whereas an elevated intake of potassium would result in excretion of a nearly equal mass of natural potassium, and hence of ^(40)K, over a short period." - ["Federal Guidance Report No. 13: Cancer Risk Coefficients for Environmental Exposure to Radionuclides"](https://www.epa.gov/sites/default/files/2015-05/documents/40...) - page 16
So, if you accept that the duration of exposure from eating a banana is 12 hours instead of 50 years, a dental x-ray is the equivalent of eating 2,347,417 bananas.