Uptake of hazardous radionuclides within layered chalcogenide for environmental protection.

Ensuring environmental protection in and around nuclear facilities is a matter of deep concern. Toward this, layered chalcogenide with CdI2 crystal structure has been prepared. Structural characterizations of layered chalcogenide suggest 'topotactic ionic substitution' as the dominant mechanism behind uptake of different cations within its lattice structure. An equilibration time of 45 min and volume to mass ratio of 30:1 are found to absorb (233)U, (239)Pu, (106)Ru, (85+89)Sr, (137)Cs and (241)Am radionuclides to the maximum extents.

Analysis of hydrological trend for radioactivity content in bore-hole water samples using wavelet based denoising.

A wavelet transform based denoising methodology has been applied to detect the presence of any discernable trend in (137)Cs and (90)Sr activity levels in bore-hole water samples collected four times a year over a period of eight years, from 2002 to 2009, in the vicinity of typical nuclear facilities inside the restricted access zones. The conventional non-parametric methods viz., Mann-Kendall and Spearman rho, along with linear regression when applied for detecting the linear trend in the time series data do not yield results conclusive for trend detection with a confidence of 95% for most of the samples. The stationary wavelet based hard thresholding data pruning method with Haar as the analyzing wavelet was applied to remove the noise present in the same data. Results indicate that confidence interval of the established trend has significantly improved after pre-processing to more than 98% compared to the conventional non-parametric methods when applied to direct measurements.

Uptake and distribution of natural radioactivity in wheat plants from soil.

The uptake of naturally occurring uranium, thorium, radium and potassium by wheat plant from two morphologically different soils of India was studied under natural field conditions. The soil to wheat grain transfer factors (TF) were calculated and observed to be in the range of 4.0 x 10(-4) to 2.1 x 10(-3) for 238U, 6.0 x 10(-3) to 2.4 x 10(-2) for 232Th, 9.0 x 10(-3) to 1.6 x 10(-2) for 226Ra and 0.14-3.1 for 40K. Observed ratios (OR) of radionuclides with respect to calcium have been calculated to explain nearly comparable TF values in spite of differences in soil concentration of the different fields. They also give an idea about the discrimination exhibited by the plant in uptake of essential and nonessential elements. The availability of calcium and potassium in soil for uptake affects the uranium, thorium and radium content of the plant. The other soil factors such as illite clays of alluvial soil which trap potassium in its crystal lattice and phosphates which form insoluble compounds with thorium are seen to reduce their availability to plants. A major percentage (54-75%) of total 238U, 232Th and 226Ra activity in the plant is concentrated in the roots and only about 1-2% was distributed in the grains, whereas about 57% of 40K activity accumulated in the shoots and 16% in the grains. The intake of radionuclides by consumption of wheat grains from the fields studied contributes a small fraction to the total annual ingestion dose received by man due to naturally existing radioactivity in the environment.