Ephemeral Radioactive Tracers for Hydrostatic Balancing Fluids When Drilling Core Samples in Radioactive Waste Tanks

An objective is to add a tracer to the balancing fluid so that the quantity (if any) of balancing fluid leaking into the core sample can be determined. Stable tracers could cause confusion when subsequent samples are taken from the same tank. Therefore, radioactive tracers with short half-lives (2 to 5 weeks, since resampling could be done after a year) and a strong gamma (for ease of counting) are preferred. The small portion that is counted would be taken from a homogenized part of the sample and would come from either a linear section (if a distribution of the leak is desired) or from the entire sample (if only the quantity leaked is sought). The temporal behavior of the counting sample activity is derived, and a dimensionless plot for interpreting the results is given.