iv FOREWORD 



The conclusions of the environmental team prompted AEC to develop a research 

 program wliich would develop the information that was not available and which would be 

 as comprehensive as possible for future assessments on the impacts of transuranic 

 radionuclides from all stages in the nuclear fuel cycle. The program was designed to take 

 advantage of the high-quality research that was already under way at the Health and 

 Safety Laboratory, the Nevada Test Site, Lawrence Livermore Laboratory, Pacific 

 Northwest Laboratory, the University of California at Los Angeles, Woods Hole 

 Ocean ographic Institute, and the University of Washington and to complement this 

 research with research projects in other geographies and climates. Research activities were 

 selected to cover all aspects of environmental transport from soil processes to ecosystem 

 cycling. The objectives of the research program were to understand the cycling behavior 

 of the transuranium elements in our environment and to determine to what degree these 

 elements would be transported to us through food chains and aerial pathways. A further 

 objective was to develop a satisfactory description of the degree to which the 

 transuranium elements persist in the environment as a first step in assessing the potential 

 hazard of these species on a historical and geological time scale. 



To achieve the broad objectives of this program, we must answer many questions. If 

 the transport of the transuranium elements is to be described, we must know to what 

 degree these elements can be mobilized in the soils and aquatic sediments where they 

 reside. A compendium of concentration ratios for plant uptake into food crops on various 

 agricultural soils must be assembled. The transport through aquatic and terrestrial food 

 chains must be quantified and appraised for the potential for human ingestion. Changes in 

 the availability of transuranic elements due to resuspension from soils also must be better 

 understood. Although the thrust of this work is on environmental transport, all the 

 research scientists are alert for unusual concentration processes that might lead to 

 radiological effects within environmental systems. 



The areas of research just mentioned are of immediate concern, but beyond these 

 near-term considerations are those related to the possible long-term persistence of the 

 transuranic elements in available form on the scale of hundreds and thousands of years. 

 Such considerations are very difficult to address adequately with contemporary research. 

 However, two approaches are under way which may provide reasonable first approxima- 

 tions to the prediction of long-term behavior. One is the theoretical approach to studying 

 the chemical and physical processes in soil of these radionuclides with the objective of 

 developing good thermodynamic data. We need information on the equilibrium 

 concentrations of the various oxidation states in different environments, on complexation 

 processes, and on diffusion coefficients for various species. We can then apply this type of 

 information to predictive modeling. An empirical approach would be to study the 

 distribution and environmental behavior of naturally occurring elements that have 

 properties analogous to those of the transuranium elements. For instance, the availability 

 for plant uptake of the rare earth neodymium, which has been subjected to weathering 

 for thousands of years, may provide a basis for predicting the uptake of americium after 

 long periods of time because americium and neodymium have quite similar chemical and 

 physical properties. Other rare earths, uranium, and thorium are also candidates as 

 analogs for some of the transuranic elements in environmental studies. 



The general areas of this program are outlined in Fig. 1. Research has now been 

 conducted for periods of time ranging from 2 yr for new work to 6 yr for work that 

 preceded this comprehensive program. Some of the results have been published in 



