Past leakage from cooling coils and rainwater intrusion are the two most likely sources. The cooling coils have been isolated, and BNL is evaluating methods to prevent rainwater from getting into the duct. The following chart shows the radionuclides of concern in the air duct. The air duct is made of concrete with a stainless-steel liner. The water level in the duct is approximately 25 feet below ground.
Radiation measurements are at normal background levels above ground, at the surface.
These data have been previously reported to regulators. To investigate possible leakage from the air duct into groundwater, BNL will be doing additional groundwater monitoring in the immediate area of the reactor complex. Because cesium and strontium tend to bind to soil, their movement in groundwater is slow. Strontium moves in groundwater less than 25 feet a year, and cesium travels less than one foot a year. For that reason, if the air duct has leaked, contamination is expected to be localized near the reactor.