Quantification of applied dose in irradiated citrus fruits by DNA Comet Assay together with image analysis.

The experiments were conducted for quantification of applied dose for quarantine control in irradiated citrus fruits. Citrus fruits exposed to doses of 0.1 to 1.5 kGy and analyzed by DNA Comet Assay. Observed comets were evaluated by image analysis. The tail length, tail moment and tail DNA% of comets were used for the interpretation of comets. Irradiated citrus fruits showed the separated tails from the head of the comet by increasing applied doses from 0.1 to 1.5 kGy. The mean tail length and mean tail moment% levels of irradiated citrus fruits at all doses are significantly different (p < 0.01) from control even for the lowest dose at 0.1 kGy. Thus, DNA Comet Assay may be a practical quarantine control method for irradiated citrus fruits since it has been possible to estimate the applied low doses as small as 0.1 kGy when it is combined with image analysis.

Evaluation of uncertainty components associated with alpha-particle spectrometric measurements of uranium isotopes in water.

Qualifications of uncertainties associated with the measurement of specific activity concentration of uranium radioisotope ((238)U) in water samples by alpha-particle spectrometry are presented. Possible sources of uncertainty are identified and quantified in the activity concentration measurements of (238)U isotope; the major source being the statistical counting uncertainty as expected. The combined relative standard uncertainty [Formula: see text] of the measurement was calculated as 1.4Bq kg(-1) (7.9%) for the investigated NPL sample. The accuracy and precision of recommended procedure were checked analysing six spiked water samples supplied from IAEA-proficiency test exercises. The results were evaluated in terms of relative bias, z-score, u-score, trueness and precision. These results show that the activity values and their uncertainties are in good agreement with recommended values.

Evaluation of the uncertainty budget for 226Ra analysis in water samples.

An alpha spectrometric method for the rapid determination of 226Ra isotope in water samples is presented. The method is based on the co-precipitation of (Ba)(Ra)SO4 for source preparation. The parameters contributing to the uncertainty budget are investigated. Geometry factor (solid angle / 4pi) was used instead of 226Ra standard disc for the determination of detector efficiency. The analytical method has been successfully applied to the determination of 226Ra for water samples in proficiency tests organized by International Atomic Energy Agency (IAEA) and National Physical Laboratory (NPL). The proposed method also showed high reproducibility.