Plutonium and Americium Behavior 



in the Savannah River Marine Environment 



D. W. HAYES and J. H. HORTON 



77?^ 23 9,240^ ^^^j '^^^Am concentrations in the Savannah River are about the same as 

 those measured in other U. S. rivers (0.25 fCi/liter and 0.05 ± 0.05 fCi /liter, respectively). 

 j^'23 9, p^^ 1^^ ^^^ Savannah River originated from the watershed ^3 9,2 4 0^^^ inventory, 

 then the net annual removal from the watershed represents 0.005% per year. This 

 indicates that thousands of years will likely pass before all the plutonium is displaced to 

 the river. Tfie plutonium and americium concentrations (highest, -^50 fCi/g (dry 

 weight)/ in sediment cores from the tidal freshwater and near the mouth of the 

 Savannah River estuary were comparable and are not greatly different from those of 

 other locations in which the only source is nuclear fallout from nuclear weapons testing. 

 The transuranic activity in these sediments represents less than 10% of the gross alpha 

 activity from the natural radionuclides that are present. Current concentrations of 

 plutonium and americium in seafoods make only a very minor contribution to the overall 

 dose commitment to humans. 



Thirteen power reactors, two fuel fabrication plants, and a U. S. Department of Energy 

 nuclear production complex, the Savannali River Plant (SRP), are operating on rivers or 

 in coastal regions of tlie soutlieastern United States. Rivers and estuaries are a major 

 geographic feature of this region and can represent both transport paths and sinks for 

 transuranics. Studies are in progress to establish the distribution and transport properties 

 of transuranic elements in the rivers and estuaries of this region. Of particular interest is 

 tlie Savannali River and its estuary because located on the watershed are tlie Savannah 

 River Plant and tliree commercial power reactors. These facilities make tlie Savannali 

 River watershed one of the most intensively developed nuclear watersheds in the United 

 States. The SRP consists of three production reactors, two fuel separation plants, a fuel 

 fabrication facility, and a heavy water plant. The SRP has been in operation since 1952, 

 whereas die three power reactors located at the headwaters of the Savannali River have 

 operated for less than 10 yr. Included in this chapter are estimates of watershed loss rates 

 for plutonium, measurements of plutonium and americium concentrations in the water 

 and sediments of tlie Savannah River and its estuary, estimates of plutonium 

 concentrations in seafood, and dose-rate estimates for seafood ingestion. 



Savannah River Basin and Estuary 



The Savannali River basin has a surface area of 27,400 km^. It can be divided into three 

 physiographic provinces that transect the basin (Fig. 1). The Blue Ridge Mountains 

 include portions of North CaroUna, South Carohna, and Georgia and range in elevation 



602 



