REP15371 - Laserfiche WebLink

Home Browse Search

ROCKY ]FLATS SOIL PLUTONIUM'"'240 SURVEYS FROM 1970 TO 1991 ' Higher resolution sampling and point data with accurate location coordinates sufficient to draw contours could highlight the area of concern more accurately. Probabilistic models and contours to definitively predict concentrations as a function of distance and direction to isolate the boundaries of those areas, respectively, are possible with the proper data. The sampling plan design that obtained the results in this report was not developed for such a level of analysis. The spati;tl distribution evident in the graphical and GIS analysis are sufficient to cleazly show that plutonium79z"0 data is not randomly distributed around Rocky Flats. The spatial distribution of plutonium is dependent on distance, direction, wind speed, wind direction, particle sizes, etc. and is tied directly to one or more past events. These events include winds either at the time of excavation and covering of the 903 Pad, 1967-1969 and or winds after the ' 903 Pad was initially capped. Given the decrease in plutonium concentrations in an eastern direction, plutonium139+2°0 correlated to particulate sizes may be a strong indicator and mechanism to base plutonium79240 concentrations as a function of distance and direction from the 903 Pad. This could be a basis to explain the reduction in plutonium79zd0 with distance from the 903 Pad. If the plutonium79+2"0 distribution was primarily caused by one source, then such a relationship would be easier to identify. The CDH data, though not quantified, strongly indicates that the 9~)3 Pad is the primary source of plutonium contamination. A mathematical relationship tied to distance would need to consider particle sizes and associated plutoniutri79370 concentrations. Part of the model would be an expression of the mechanistic process that resulted in the release of plutonium23'210. Wind speed and wind direction would be additional variables to perform sensitivity analysis to isolate conditions that occurred during the release from the 903 Pad. The CDH Health Studies on Rocky Flats are developing this portion of the model. The other part of the model would be an explanation of plutonium concentrations now press:nt in the soils. Contours would be drawn from this model and compared to the observation. Statistical analysis would be used to compare the accuracy of the observations to model results. The later part of the model is the subject of DOE RFURI work under the Interagency Agreement IAG with DOE, CDH and EPA. (USDOEa; USDOEb) l 1 23