Determination of the solubility and size distribution of radioactive aerosols in the uranium processing plant at NRCN.

Inhalation is the main route of internal exposure to radioactive aerosols in the nuclear industry. To assess the radiation dose from the intake of these aerosols, it is necessary to know their physical (aerodynamic diameter distribution) and chemical (dissolution rate in extracellular lung fluid) characteristics. Air samples were taken from the uranium processing plant at the Nuclear Research Center, Negev.

Normalisation of spot urine samples to 24-h collection for assessment of exposure to uranium.

For dose assessment of workers at Nuclear Research Center Negev exposed to natural uranium, spot urine samples are analysed and the results are normalised to 24-h urine excretion based on 'standard' man urine volume of 1.6 l d(-1). In the present work, the urine volume, uranium level and creatinine concentration were determined in two or three 24-h urine collections from 133 male workers (319 samples) and 33 female workers (88 samples).

An improved method for Organic Bound Tritium (OBT) determination in urine samples.

The Organic Bound Tritium (OBT) amount in the body may induce changes in the evaluation of the internal exposure to tritium, due to its different retention time relative to HTO. OBT measurements for urine are not performed routinely, mainly because of the lengthy work needed in preparation of the samples, when using the standard oxygen combustion method. A simpler and more rapid method based on liquid scintillation counting (LSC) was employed, and an evaluation was performed to check its suitability for urine samples.

MDA improvement technique for lung counter measurements of uranium workers.

A practical and simple method was employed to improve the minimum detectable activity (MDA) for lung counting measurements by summing several accumulated spectra. The method was checked for natural uranium, which produces peaks due to photon energies of 63.3, 92.

Determination of parameters relevant to alpha spectrometry when employing source coating.

The recoil fragments from an alpha-emitting source may cause significant detector contamination. The simplest method to avoid the problem is to use a source coating. The influence of Mylar film coatings of different thickness on the resolution, efficiency and minimum detection level of an alpha spectrometry system was investigated.