Reproduction of shielding concrete activation measurements by simulations.

With the increasing number of decommissioning projects, radioactive waste estimation of biological shielding concretes is becoming more and more important. Simulation tools supporting this activity, like MCNP and Cinder are already available; however, publicly available neutron spectra in shielding concretes are limited. The aim of the study was to present and evaluate possible model arrangements for accurate neutron transport to deeper points of shielding concretes from the reactor pressure vessel. Representation of reality, neutron behavior and activity generation of seven long-lived radioisotopes (54Mn, 60Co, 65Zn, 133Ba, 134Cs, 152Eu and 154Eu) were assessed in each arrangement. After evaluating several model geometries, a conical shape neutron reflecting surface was shown to be the most suitable one to reproduce neutron fields in deeper layers of shielding concretes from a monodirectional initial neutron source.

DOSE ASSESSMENT WITH DIFFERENT METHODS AFTER EXPOSURE TO 14C-LABELLED COMPOUNDS.

An accidental intake of 14C-labelled compound has been followed by long-term monitoring of urine samples. First, the intake and the committed effective dose have been calculated by a generally recommended method and as the value exceeded the investigation level, special dose estimation was performed. Recommendations from ICRP Publications were used for analyses but the measurement data did not fit these models, so the recommended parameter values were deemed incorrect for this compound and this exposure situation. With the measurement data, it was possible to set up a case-specific model based on the actual excretion functions. Afterwards, the committed effective dose was obtained from integrating the total number of decays in the body over 50 y. This case shows that 14C-labelled organic compounds could be very unique when they get incorporated into the body and the absorption and deposition parameters should be used with special care when estimating the dose.

Effects of the uncertainty contributions on the methods used for measurement uncertainty evaluation.

Adequate measurement uncertainty evaluation is crucial for supporting basic measurement purposes. However, the most prevalent approach, the uncertainty propagation, may not be validly applicable under certain conditions which require the use of less restricted alternative method (MCM-based propagation of distributions). We demonstrate the effects of major conditions, e.g. non-linear measurement model, non-Gaussian input quantities, on the reliability of uncertainty evaluation methods, highlighting the importance of the less frequently examined impact of uncertainty component contributions to the standard uncertainty of measurand.

Evaluation of Hungarian monitoring results and source localization of the 106Ru release in the fall of 2017.

Anthropogenic 106Ru has been detected in the environment from late September to early October 2017 by several European environmental radiological monitoring networks. The paper presents the comprehensive evaluation of Hungarian monitoring results related to the occurrence of 106Ru in various environmental compartments (airborne particulates, deposition, plants, and terrestrial indicators), which was implemented to determine the temporal and spatial variation of the contaminant on a national scale and also to verify the findings based on the data arising from environmental monitoring at a local scale in Budapest. Difficulties in direct comparison of the diverse reported data were also considered; results arising from varied sampling periods were corrected with account taken of the relation between the sampling duration and 4-day-long plume residence (estimation based on the daily monitoring of air and backward trajectory analysis). Integrated analysis of air and deposition measurements and meteorological data was also performed; the deposition processes were investigated by establishing the correlations of activity concentrations measured in the atmosphere and in the deposition samples. In order to study the temporal distribution and spatial localization of the 106Ru contamination and to interpret the measurements at ground level, backward trajectory analysis was performed with HYSPLIT model. The backward trajectory simulations suggested that the release had probably occurred during the last week of September 2017 from the geographical area between Volga and the Urals. In addition, assessment of the doses due to the 106Ru release was implemented considering external exposure from cloudshine and groundshine and internal exposure via inhalation.

Methods, results and dose consequences of 106Ru detection in the environment in Budapest, Hungary.

From late September to early October of 2017, the majority of European networks involved in environmental radiological monitoring - including the environmental monitoring system of the KFKI Campus in Budapest - detected 106Ru isotope of artificial origin in the atmosphere. The reported values higher than the minimum detectable activity (MDA) concentrations were in the range of 0.8 µBq/m3 - 145 mBq/m3. Based on the results of environmental measurements and the available meteorological data, assessments were made to analyze concentration levels of 106Ru activity and to help understand the behavior of radioruthenium in various environmental media. Evaluation of the daily variation of activity levels indicated a maximum of 4 day-long residence time of 106Ru contamination presence in ground level air in Budapest. An average 106Ru activity concentration of 25.6 ±â€¯1.4 mBq/m3 have been observed for the estimated residence time of 106Ru in the air. Deposition of 106Ru was dominantly influenced by rainfall, the major contributor wet deposition which led to an average of 11.3 ±â€¯1.3 Bq/m2 deposition on the ground surface prior to plume passage.

The role of analogues in radioecology.

If no data are available for a specific radionuclide its analogue could be used in radioecological models. They might be used not only in the frame of screening modelling. Relevant processes and features have to be known, such as time scales of these processes, physical, chemical and biological properties of the environment and relevant media. An analogue could only be proven to be valid by comparing its behaviour in the conditions of interest, while confidence in the validity of an analogue will increase as the quality of the justification increases, there will always be some residual uncertainty. Several main types of analogy can be used when measured or recommended values are not available: the same parameter obtained for another isotope of the same element; the same parameter obtained for another element; a different parameter obtained for the same element. There are several cases, when analogues might be applied as indicators of the determining processes in the radioecological studies.