J. Solymosi

Determination of radioactive bulk and surface concentration by beta-detection: I. Quantitative analysis

The activity concentration of bulk and surface samples contaminated with β-emitting radioisotopes is difficult to measure without the “a priori” knowledge of the nature of the non-gamma emitting components. Beta-emitters cannot be identified from any measured spectral distribution. The counting efficiency of the measuring system changes significantly with β-energy so it cannot be assumed to have a single value obtained with a standard source with known energy. Application of an energy selective β-detector is introduced for determining bulk and surface activity concentration. Samples of “infinitely thick” or “infinitelythin” nature are to be prepared. The distribution of β-energy deposited in the detector is registered as counts in 8 or 16 energy intervals. No information is needed on the qualitative composition of the sample. Normalised integral distributions (intensity ratios) are derived from the count rates of the intervals. These distributions are then compared to calibrated intensity ratios obtained with suitable standard sources. An average (effective) counting efficiency is generated from this comparison by a special algorithm. Activity concentration of an unknown sample is then obtained using this average efficiency. Calibration and sensitivity data are presented for different types of bulk and surface samples.

Dosimetric measurement of the disintegration rate of fission products

Investigations on the disintegration rate of fission products of238U and239Pu are presented. The intensity of the β- and γ-radiation of fission products were measured continuously in an interval of 1–1300 hours following the fission, offering the possibility for determining the general and specific characteristics of the individual fission products. A universal measuring procedure was elaborated for the rapid in situ determination of the dosimetric features of fission products, which is suitable for the accurate evaluation and prediction of external absorbed dose even in case of fission products of various origin and unknown composition.

Application of radioisotope-excited X-ray fluorescence to the determination of trace elements in blood

A radioisotope-excited energy-dispersive X-ray fluorescence system has been constructed and used for the analysis of blood samples for trace elements. The possibility of determination of trace elements in blood by X-ray fluorescence based on comparison with standard reference materials has been outlined and the applicability of the method demonstrated by the analysis of blood samples. The method enables fast, non-destructive direct analyses to be carried out without lengthy sample pretreatment on a routine basis.

Automated separation process for radioanalytical purposes at nuclear power plants

Chemical separation processes have been developed to remove the matrix components and thus to determine fission products, especially radioiodine nuclides, in the primary coolant of WWER-type nuclear reactors. Special procedures have been elaborated to enrich long-lived nuclides in waste waters to be released and to separate and enrich caesium isotopes in the environment. All processes are based mainly on ion-exchange separations using amorphous zirconium phosphate. Automated equipment was constructed to meet the demands of the plant personnel for serial analysis.