Relationship of Tritium in Milk and
Groundwater Around the Hanford Site

Ted M. Poston, Mona L. Wright*, and David J. Vanni

Pacific Northwest National Laboratory

Public concern about tritium in the environs around Hanford prompted the Site Environmental Surveillance Project to initiate monitoring of milk using electrolytic enrichment of water distilled from whole raw milk. Prior monitoring results using a direct liquid scintillation counting method was not sensitive enough to detect concentrations of tritium in milk (MDC of 300 pCi/L). Initial results in 1998, while low, suggested that concentrations at Sagemoor were twice the levels at Wahluke and three times the level at Sunnyside, a generally upwind reference site. The Sagemoor and Wahluke sampling areas are located in a generally downwind position relative to the Hanford site. The routine contract laboratory had matrix problems resulting in method high blanks for electrolytic enrichment tritium analysis. Samples were sent to the University of Rochester for tritium analysis by helium-3 in-growth. Concentrations of tritium in dairy milk are positively correlated with concentrations in groundwater used by the dairies. Present concentrations of dairy groundwater exceed background river concentrations and likely reflect historic accumulation from past irrigation practices and ground water recharge. Additional investigation is needed to better quantify influence of groundwater recharge and residence in the sampling areas.

* Presently with U.S. Army Corps of Engineers, Walla Walla, Washington