And you are proposing that none of the Cesium 137 escaped into the ambient environment during the 19 year exposure period? That is statistically impossible. The source had ha mechanical shutter that allowed it to be directly exposed to the environment for almost 20 years, with no human to maintain it. Corrosion, spalling, and release of radioactive material though freeze-thaw cycles are all ways that bits of the source can become liberated.

Are you also proposing that this was the only experiment that released radionuclides into the environment at BNL? I certainly remember the furor of them getting caught pissing tritium into the groundwater. I am sure there are many, many things they did which were not detected.

https://www.gao.gov/products/rced-98-26

It is well know and well documented that the defense industry has taken a cavalier approach to public nuclear safety from it’s very inception. And make no mistake, BNL exists primarily as a national defense asset.