>>13962586>>13962666checkem
According to this dataheet (
https://ehs.missouri.edu/sites/ehs/files/pdf/isotopedata/sr-90.pdf), you would need more than a centimeter of plastic to shield from it, so I think a good portion of the radiation can escape to his unfortunate rectum.
>>13962584>>13962617The radiation strongly irradiates the organs near the source, it would probably cause necrosis, but even a very short exposure would lead to severe burn-like damage of his ass, and a seriously increased chance of developing cancer (granted he survives). If he leaves it up for longer, I think he pretty much destroys the lower half of his gastrointestinal tract.
The dosage received by Litvinenko is estimated to be between 20Gy to 100Gy.
Also, I learned these long ago, so I'm not 100% sure.