Radiocesium (¹³⁷Cs) accumulation by fish within a legacy reactor cooling canal system on the Savannah River Site

The aquatic cooling canal system associated with a nuclear reactor built in the early 1950s received accidental releases of radiocesium (¹³⁷Cs) from the reactor between 1954 and 1964, resulting in the dispersion of ~8.2 × 10¹² Bq of ¹³⁷Cs into the associated canals and ponds. The primary purpose of this study was to document concentrations of ¹³⁷Cs in littoral zone fish currently occupying components of the cooling canal system, 3 canals and 2 impoundments, to determine how concentrations varied among these various components. Secondarily, we examined for potential influence of weirs within the canal system on concentrations in fish as well as the potential relationship between fish species and body size and on ¹³⁷Cs concentrations in fish. We collected samples of sediment, biofilm, and fish from each component of the R-Reactor cooling system and compared ¹³⁷Cs among sites and species in individual sites. Concentrations of ¹³⁷Cs in sediments, biofilms and mosquitofish varied significantly among sampling areas with higher concentrations in RCAN1, a canal segment that was the closest to the reactor and received reactor effluent for a longer period than other components. Comparisons among other components of the cooling system, and species comparisons relative to presumed trophic positions and fish length were not consistent. However, littoral zone fish in the cooling canal system continue to bioaccumulate ¹³⁷Cs >50 years after the original releases of contamination.