A comparison of different detection techniques for 137Cs measurements of cattle in vivo.

Agricultural lands with farm animals (e.g. cattle) can be significantly affected by radioactive contamination following nuclear or radiation accidents. In order to optimise the techniques for measuring 137Cs in contaminated cattle, selected radiation detectors have been tested and calibrated using volumetric radiation sources. In addition, a mathematical phantom of a cow was created within Monte Carlo simulations. The main aim of the research was to propose a method for making rapid measurements of 137Cs in cattle in vivo/in situ and to select the most suitable measurement set-up. Measurements of contaminated cattle in vivo were carried out in Belarus with one selected detector, and were then compared with measurements of meat in a laboratory and with measurements of a control group of cows. The proposed measurement method was also tested on measurements of 137Cs in wild boars in Czechia with higher levels of the 137Cs activity.

Ingestion intakes of 137Cs by the Czech population: Comparison of different approaches.

Ingestion intakes of 137Cs of the Czech population were calculated in two different ways - either from the measured activity of 137Cs in components of food in combination with statistical data about consumption rates or from retention of 137Cs in the human body obtained by whole body counting or calculated from daily urinary excretion of 137Cs. Data from the time period since 1986 to 2015 are used. The daily ingestion intake was about 25 Bq d-1 in 1986 and is around 0.1 Bq d-1 at present. Both approaches of ingestion intake calculation have their advantages and disadvantages. Ingestion intake calculated from 137Cs body content was assumed to be the most accurate as it requires fewer assumptions than the calculation from food consumption. However, calculation of 137Cs intake from food consumption is an important tool for prediction doses after the release of radionuclides into environment. The best agreement exceeding the intakes from urine measurement 5 times at maximum was achieved when intakes calculated from food also included products from the natural environment. Without this, the ingestion intake could be under-predicted seriously up to 6 times, especially in the longer time after the release of 137Cs into environment. Ingestion intakes up to 11 Bq d-1 in a group of people with significant consumption of game meat containing elevated activity of 137Cs activity were included as a special case. Various groups of foodstuffs had varying effects on the total committed effective dose from 137Cs. Dose estimates for the Czech population from 137Cs ingestion intake achieved 80 µSv in 1986 and not more than 2 µSv currently and were similar to those incurred by the population of neighbouring countries.

Fractionation of (137)Cs and Pu in natural peatland.

High Cs-137 concentrations in plants growing on peatland inspired us to investigate the quantity of its bioavailable fraction in natural peat. Our investigation aims to: a) estimate the quantity of bioavailable Cs-137 and Pu present in peat, b) verify the similarity of Cs-137 and K-40 behaviours, and c) perform a quantification of Cs-137 and Pu transfer from peat to plants. We analysed the vertical distribution of Cs-137 and Pu isotopes in the peat and their concentrations in plants growing on these places. Bioavailability of radionuclides was investigated by sequential extraction. Sequential analyses revealed that it was the upper layer which contained the majority of Cs-137 in an available form while deeper layers retained Cs-137 in immobile fractions. We can conclude that 18% of all Cs-137 in the peat is still bioavailable. Despite of the low quantity of bioavailable fraction of Cs-137 its transfer factor reached extremely high values. In the case of Pu, 64% of its total amount was associated with fulvic/humic acids which resulted in the high transfer factor from peat to plants. 27 years after the Chernobyl nuclear accident, the significant part of radionuclides deposited in peatland is still bioavailable.