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The L6 chondritic meteorite, HaH-346, fell in Libya. However, neither the exact date of the fall nor the exact size of the original meteoroid or asteroid is known. A specimen of the meteorite, weighing 488 g, was measured using ultra low-background gamma-ray spectrometry in the 225 m deep underground facility HADES. Activation products 22Na, 26Al, 60Co, 57Co, 54Mn and 44Ti were detected. The detection efficiency was determined by 3D scanning the meteorite and introducing this in the computer model of the detector and sample implemented in the MCNP6.2 Monte Carlo code. The activities of 22Na and 26Al support the hypothesis that the fall took place on 26 August 2018. Furthermore, the 60Co and 26Al activities indicate that the original radius of meteoroid was between 50 and 80 cm, which suggests the mass prior to atmospheric entry was between 2400 and 7300 kg.

National Centre for Nuclear Research, NCBJ is one of the biggest research institutes in Poland, in which scientists deal with basic research in the various fields of subatomic physics, development of nuclear technologies and practical applications of nuclear physics methods, including those for nuclear medicine and radiotherapy. NCBJ operates the only Polish nuclear research reactor MARIA, around which a Reactor Laboratory for Biomedical Research, RLBR has been built in the last 4 years. One of the main aims of the RLBR team is to adapt the H2 channel, one of the eight MARIA’s horizontal channels, to a specific irradiation facility delivering a high flux thermal/epithermal neutron beam. The beam derived from the channel will be a tool for biological, physical and material studies for Boron Neutron Capture Therapy, BNCT. While NCBJ is focused on building a neutron research facility, the Polish scientific community expressed its interest in BNCT development and implementation as an alternative therapy for cancer treatment. Through the working group meetings organized in the form of regular scientific workshops since 2015, it led to the establishment of a national scientific consortium dedicated to BNCT. Polish Consortium for Boron Neutron Capture Therapy agreement was initially signed by twelve institutions including scientific institutes, universities and oncological centres in October 2019. National Centre for Nuclear Research was appointed the leader of the consortium. A year later the consortium was enlarged by two more institutions.

A model of REM-2-type chamber was modeled with MCNPX code to study the dose-response to monoenergetic neutrons in wide energy range from thermal to 20 MeV for various compositions of gas in the chamber. The energy dependence of the total dose absorbed in the filling gas was compared with the energy dependence of ambient absorbed dose D*(10) and with experimental data. The results of the studies will be useful for designing new, improved generation of recombination chambers.

International audience; Following a nuclear incident, 131I monitoring is usually carried out by performing in vivo measurements of the retained activity in the thyroid. The measurement equipment needs to be calibrated in order to convert thyroid count rates into retained activity. This calibration relies on measurements or Monte Carlo computations using appropriate anthropomorphic model of the thyroid gland contaminated with a known activity of the radionuclide of interest. Several factors influence the calibration procedure, such as the geometry, the individual anatomical characteristics, and the presence of 131I in other organs and tissues of the body. In particular, given their age-dependent anatomical changes, appropriate values of detector efficiencies for children are necessary to reduce results uncertainties when children are involved. In this study, Monte Carlo simulations for several detectors and phantoms of different ages have been performed to investigate the variation of the detection efficiency with distance, age and thyroid volume. It was found that the counting efficiency varies linearly with the thyroid volume and inversely with the squared detector-phantom distance. Age-dependent correction factors to be applied to the adult calibration factor have been derived and can be used when calibration factors for children are not available. © 2019 Elsevier Ltd

Radiotherapy of pregnant cancer patients is not common, but when applied accurate assessment of the fetus dose is required, especially since the treatment planning systems are not able and do not allow accurate assessment of out-of-field doses. Proton therapy significantly reduces out-of-field doses, such as dose to the fetus, when compared to the photon radiotherapy techniques and as such could be promising for pregnant cancer patients. Within this study Monte Carlo calculations are performed on the three different computational phantoms representing pregnant women, all in second trimester of pregnancy. Simplified proton beam to the pregnant women brain was modelled, and the total dose equivalent (normalized per target dose) to the fetus was calculated. Between MCNPX and MCNP6.2 code versions we observed up to 6% difference. In this work 3 groups participated and the variation between the groups was 8% and 12% for MCNPX and MCNP6.2, respectively. Depending on the phantom used in the calculations the fetal dose was between 0.4 and 0.8 {\mu}Sv/Gy. Major contribution to the total dose came from the neutrons, with only 20% of the dose coming from photons, while other particles have negligible contributions. Results of the total dose equivalent differ by factor of two, when different phantoms were used, due to geometrical and anatomical characteristics of mother and fetus position., Comment: 18 pager, 3 figures, 6 tables plus 2 supplemental tables

An intercomparison exercise is described that examines Monte Carlo modelling of anthropomorphic voxel phantoms in an idealized ground-contamination photon exposure scenario. Thirteen participants calculated and submitted organ and effective dose rates for comparison against a set of verified reference solutions. The effective dose rates are shown to agree with the reference value to within reasonable statistical uncertainties in five of the cases, though in only one of those was similar agreement also demonstrated in the evaluation of all requested organ dose rates. Orders-of-magnitude differences in doses are seen for some of the other participants, both internally within their own dataset and also relative to the reference solutions. Following limited feedback and suggestions from the organizer, up to two sets of revised solutions were resubmitted by some of the participants; these generally exhibited improved agreement, though not always. The overall observations and conclusions from this intercomparison exercise are summarized and discussed., 19 pages, 7 figures, 3 tables

International audience; Following a severe nuclear reactor accident large amounts of radioactive iodine are released in the atmosphere. Health consequences estimation for the affected population is based on the dose assessment which can be derived from in vivo measurements. Since the uptake of radioactive iodine increases the thyroid cancer risk of children it is of particular interest to dispose of technical recommendations on thyroid monitoring, particularly for children.This paper summarizes recommendations that have been issued by a group of European radiation protection specialists during the CAThyMARA project. It covers technical aspects such as the choice of instruments, the calibration process, the measurement preparedness, the dose assessment and communication issues. This paper also discusses remaining gaps and serves as an introduction to other papers of this special issue.

This work summarises the results of a comparison organized by EURADOS focused on the usage of the ICRP Reference Computational Phantoms. This activity aimed to provide training for the implementation of voxel phantoms in Monte Carlo radiation transport codes and the calculation of the dose equivalent in organs and the effective dose. This particular case describes a scenario of immersion in a 16N beta source distributed in the air of a room with concrete walls where the phantom is located. Seven participants took part in the comparison of results using GEANT4, TRIPOLI-4 and MCNP family codes, and there was detected a general problem when calculating the dose to skeletal tissue and the remainder tissue. After a process of feedback with the participants the errors were corrected and the final results reached an agreement of +/-5%., 18 pages, 4 figures, 2 tables

The aim of this work is to present the method for sequential plutonium and americium activity determination in air filters using chromatographic radionuclide separation and alpha spectrometry measurement. The developed method may be employed for the purposes of workplace monitoring and as an indicator of the need of introducing the individual monitoring as well as a useful complementation of individual monitoring. Basic parameters describing the developed method such as values of chemical recoveries and minimum detectable activities for plutonium and americium isotopes have been determined. Applied counting efficiency was obtained using Monte Carlo calculation method.

This paper presents the set of procedures developed in Radiation Protection Measurements Laboratory at National Centre for Nuclear Research for evaluation of shielding properties of high performance concrete. The purpose of such procedure is to characterize the material behaviour against gamma and neutron radiation. The range of the densities of the concrete specimens was from 2300 to 3900 kg/m3. The shielding properties against photons were evaluated using 137Cs and 60Co sources. The neutron radiation measurements have been performed by measuring the transmitted radiation from 239PuBe source. Scattered neutron radiation has been evaluated using the shadow cone technique. A set up of ionization chambers was used during all experiments. The gamma dose was measured using C-CO2 ionization chamber. The neutron dose was evaluated with recombination chamber of REM-2 type with appropriate recombination method applied. The method to distinguish gamma and neutron absorbed dose components in mixed radiation fields using twin detector method was presented. Also, recombination microdosimetric method was applied for the obtained results. Procedures to establish consecutive half value layers and tenth value layers (HVL and TVL) for gamma and neutron radiation were presented. Measured HVL and TVL values were linked with concrete density to highlight well known dependence. Also, influence of specific admixtures to concrete on neutron attenuation properties was studied. The results confirmed the feasibility of approach for the radiation shielding investigations.

The aim of this work was to create a numerical model of scintillation detector and to check whether such detector can be used for the measurements of internal contamination in emergency conditions. The purpose of the measurements would be only detection of possible contamination, without identification of radioactive isotopes, and hence without estimation of effective dose. However, in emergency conditions, it is sufficient for the rapid selection of a group of contaminated persons, who should be subjected to careful inspection in the laboratory conditions. The calculations were performed for three detector positions relatively to the phantom. The distribution of dose rate was also calculated, in order to find the best geometry for dose rate measurements around human body. Another problem under consideration was the possible influence of radioactive contamination in the environment on the registration of the gamma spectrum emitted from the whole body phantom. Performed calculations showed that there is a possibility to measure internal contamination outside laboratory, even in contaminated area.

An intercomparison on in-vivo monitoring for determination of 241Am in three skull phantoms was launched by EURADOS in 2011. The project focused on the measurement and estimation of 241Am activity in the human skull. Three human skull phantoms of different complexity were used. A Monte Carlo (MC) exercise with the voxel representations of the real phantoms was also launched in September 2012. The main goals of the project were to investigate the use of MC techniques for efficiency calibrations for body monitoring systems for a special calibration exercise and compare the approaches of participating laboratories. The full MC exercise consisted of three tasks with increasing difficulty, to test the extent of the skills of each participating laboratory. The first task in this intercomparison was to simulate a specified detector and a well defined semi-skull phantom. All parameters of the simulation, including photon yield, material property and geometry were fixed. This paper provides an overview of the participants’ results and analyses of the issues presented by this first task. The majority of the responses did not need any correction and the number of incorrect results was less than in a previous exercise of a similar kind. Overall knowledge in this research area utilising MC techniques appears to have improved and the repetition of the intercomparison exercise has positively affected the skills of the participating laboratories.

International audience; An intercomparison on in-vivo monitoring for determination of 241Am in three skull phantoms was launched by EURADOS in 2011. The project focused on the measurement and estimation of 241Am activity in the human skull. Three human skull phantoms of different complexity were used. A Monte Carlo (MC) exercise with the voxel representations of the real phantoms was also launched in September 2012. The main goals of the project were to investigate the use of MC techniques for efficiency calibrations for body monitoring systems for a special calibration exercise and compare the approaches of participating laboratories. The full MC exercise consisted of three tasks with increasing difficulty, to test the extent of the skills of each participating laboratory. The first task in this intercomparison was to simulate a specified detector and a well defined semi-skull phantom. All parameters of the simulation, including photon yield, material property and geometry were fixed. This paper provides an overview of the participants' results and analyses of the issues presented by this first task. The majority of the responses did not need any correction and the number of incorrect results was less than in a previous exercise of a similar kind. Overall knowledge in this research area utilising MC techniques appears to have improved and the repetition of the intercomparison exercise has positively affected the skills of the participating laboratories. © 2013 Elsevier Ltd.