Zusammenfassung Die Wege für eine sichere Entsorgung hochradioaktiver Abfälle sind vielfältig und bleiben eine zentrale politisch-gesellschaftliche Herausforderung. Umweltverträglichkeit, Gesundheitsschutz und sozialer Frieden sind nur einige Aspekte, denen eine zukunftsgerichtete Endlagerung gerecht werden muss. Vor diesem Hintergrund ist es eine zentrale Aufgabe, zieladäquate Zukunftspfade der nuklearen Entsorgung hochradioaktiver Abfälle zu identifizieren, zu analysieren und zu bewerten – dies steht im Mittelpunkt dieses Beitrags. Ziel ist zum einen eine vergleichende Betrachtung der identifizierten Pfade hinsichtlich ihrer Priorisierung und Charakteristika. Zum anderen werden aus den Pfaden übergeordnete Strategien zum Umgang mit Ungewissheiten abgeleitet. Insgesamt wurden sieben Zukunftspfade identifiziert und hinsichtlich ihrer Plausibilität und Umsetzungswahrscheinlichkeit eingeordnet. Die einzelnen Pfade werden im Beitrag zunächst dargestellt mit einem besonderen Augenmerk auf drei Pfaden, die als sehr wahrscheinlich eingestuft wurden. Darauf folgt eine vergleichende Pfadbetrachtung aus dem Blickwinkel von Gewissheiten und Ungewissheiten als Kernthema des Beitrags. Daraus werden drei übergreifende Strategien der Ungewissheitsbewältigung bei Entsorgungspfaden hochradioaktiver Abfälle herausgearbeitet.

Interventional cardiology is characterized by high radiation exposure for both the patient and the operator. Adequate shielding and monitoring of the operator are fundamental to comply with radiation protection principles. In a previous work, the effect on the dose of the dosemeter position on the chest was studied. In this paper, the investigation has been completed, employing an anthropomorphic thorax phantom, equipped with arms. Although there are differences between the Monte Carlo simulations and the measurements, similar trends are observed, showing that the reduction in dose, due to the arms, is between 20 and 60%, compared with the situation without arms. For that reason, considering a dosemeter placed on the chest, the upper position, which is the least affected by the arms, should be preferred while the extreme lateral position, near the armpit, should be avoided.

This study investigated the feasibility of combining high-resolution gamma-ray spectroscopy with the simulation capabilities of the Nucleonica Nuclear Science Portal with the aim to determine the properties of Cf sources. In this contribution, we present the results for a 20-month-old and a 49-year-old Cf source. In particular, the question arises whether the neutron emission rate can be determined using gamma-ray spectroscopy.

The spontaneous fission and neutron emission properties of Californium sources serve as a unique tool to analyze and validate the quality of detection of fission products. State-of-the-art methods for determining the age of a young Cf source were re-examined and modified. Further improvement included the determination of the single Cf isotopes within the Cf source and the neutron emission rate of the source. The analysis was performed by comparing the simulated gamma-ray spectra of the Nucleonica suite with measured data of a young Cf source employing an HPGe detector. In addition, with the evaluation of the 133.5 keV peak (mainly due to the beta-decay Ce-144/Pr-144) in relation to a peak at 497.1 keV (mainly due to the beta-decay Ru-103/Rh-103) or 724.3 keV (multiplet, dominated by Ru-105/Rh-105 and Ce-145/Pr-145), the age-determination method of the investigated Cf source could be considerably improved to a confined age of 20 +/- 3 months. By means of decay simulations, some deficiencies of current techniques in determining the isotope abundances were introduced. In particular, the quantities of Cf-252 and Cf-249 were analyzed extensively. Consequently, the source's neutron emission rate matched well the emission rate from the source's certification. The difficulties of defining the abundance of additional Cf isotopes within the source, albeit with lesser importance, are also illustrated.

EURADOS (European Radiation Dosimetry Group) Working Group 12 (WG12) SG1 activities are aimed at occupational radiation protection and individual monitoring in X-ray and nuclear medicine practices. In recent years, many studies have been carried out in these fields, especially for interventional radiology and cardiology workplaces (IC/IR). The complexity of the exposure conditions of the medical staff during interventional practices makes the radiation protection and monitoring of the exposed workers a challenging task. The scope of the present work is to review some of the main results obtained within WG12 activities about scattered field characterization and personal dosimetry that could be very useful in increasing the quality of radiation protection of the personnel, safety, and awareness of radiation risk. Two papers on Monte Carlo modelling of interventional theater and three papers on active personal dosimeters (APDs) for personnel monitoring were considered in the review. More specifically, Monte Carlo simulation was used as the main tool to characterize the levels of exposure of the medical staff, allowing to determine how beam energy and direction can have an impact on the doses received by the operators. Indeed, the simulations provided information about the exposure of the operator’s head, and the study concluded with the determination of an eye-lens protection factor when protection goggles and a ceiling shielding are used. Moreover, the review included the results of studies on active personal dosimeters, their use in IC/IR workplaces, and how they respond to calibration fields, with X-ray standard and pulsed beams. It was shown that APDs are insensitive to backscatter radiation, but some of them could not respond correctly to the very intense pulsed fields (as those next to the patient in interventional practices). The measurements during interventional procedures showed the potential capability of the employment of APDs in hospitals.

Personnel involved in interventional practices are likely to be exposed to higher radiation doses than other workers in the medical field. Personnel monitoring and radiation protection measures play a crucial role in keeping these doses below the limits. EURADOS (European Radiation Dosimetry Group) Working Group 12 performed a series of investigations showing how the complexity of the scattered field reaching the operators can influence the doses to the operators. The present work was aimed at determining the possible effects on the registered doses of the scattered field and the actual position of a dosemeter on apron. This study has been performed through Monte Carlo simulations and it was validated through measurements. It does not claim to identify the 'best' position for the dosemeter, but to assess the variability of its response, showing how a variability of the order of +/- 30% to 40 should be taken into account.

Deep geological disposal with provisions for retrieval is one of the most promising strategies for the definite management of high-level nuclear waste. However, retrieval of disposed waste might require certain extensive work of personnel near the waste package that might also enhance the level of radiation exposure. Hence, a precise estimation of the personal dose with consideration of realistic body postures is highly desired for optimization of individual working scenarios. In this study, the near field of a generic geological disposal facility was modeled with a horizontal emplacement drift in saline host rock. Inside the drift, a shielded disposal cask loaded with spent nuclear fuel was placed on the ground. A whole-body stylized phantom with moveable limbs was applied to represent a reference worker. Several relevant realistic body postures that might be encountered in a disposal facility were investigated. The corresponding radiation exposure was calculated and compared with a general-purpose Monte Carlo code. (C) 2021 Elsevier Ltd. All rights reserved.

We investigated different concrete samples with respect to their gamma-radiation transmission properties of Cs-137. From results of gamma-spectroscopic measurements, respective half-value layers are presented for ordinary, hematite, and barite concrete. The outcomes are compared to literature values. In addition, CT scans were performed and analyzed to reveal structural impacts on shielding properties. Finally, Monte-Carlo simulations were performed to examine the reliability of theoretical predictions. As a result, precise specification of the concrete composition is essential to simulate shielding designs of new facilities, as accurate theoretical predictions are necessary to avoid excessive costs due to oversizing or rework.

In order to address the recent concerns over a possible increasing in brain tumour mortality among interventional radiologists and cardiologist, this work evaluated the exposure conditions of the operator's brain during interventional procedures using Monte Carlo simulations with anthropomorphic phantoms. The absorbed doses in several predefined segments of the operator's brain were estimated in a typical interventional radiology irradiation scenario. The doses were normalized to the KAP values simulated for ten X-ray beam qualities and four projections (PA, RAO 25°, LAO 25° and CRA 25°). For the interventional radiology scenario, because of the position of the operator, no difference was found in the exposure between the left and right regions of the brain for the first operator. However, for the second operator standing at a farer distance from the tube, the exposure of the left part of the brain is up to two times higher than that of the right part. The results are in agreement with dose measurements reported in the literature. The conversion factors, obtained as the absorbed dose per KAP, can be used to obtain a first estimate of the exposure of the brain of the operators during interventional procedures.

Interventional radiology and cardiology are widespread employed techniques for diagnosis and treatment of several pathologies because they avoid the majority of the side-effects associated with surgical treatments, but are known to increase the radiation exposure to patient and operators. In recent years many studies treated the exposure of the operators performing cardiological procedures. The aim of this work is to study the exposure condition of the medical staff in some selected interventional radiology procedures. The Monte Carlo simulations have been employed with anthropomorphic mathematical phantoms reproducing the irradiation scenario of the medical staff with two operators and the patient. A personal dosemeter, put on apron, was modelled for comparison with measurements performed in hospitals, done with electronic dosemeters, in a reduced number of interventional radiology practices. Within the limits associated to the use of numerical anthropomorphic models to mimic a complex interventional procedure, the personal dose equivalent, H p (10), was evaluated and normalised to the simulated Kerma-Area Product, KAP, value, indeed the effective dose has been calculated. The H p (10)/KAPvalue of the first operator is about 10 μSv/Gy.cm2, when ceiling shielding is not used. This value is calculated on the trunk and it varies of +/-30% moving the dosemeter to the waist or to the neck. The effective dose, normalised to the KAP value, varies between 0.03 and 0.4 μSv/Gy.cm2. Considering all the unavoidable approximation of this kind of investigations, the comparisons with hospital measurement and literature data showed a good agreement allowing to use of the present results for dosimetric characterisation of interventional radiology procedures.

To store and dispose spent nuclear fuel, shielding casks are employed to reduce the emitted radiation. To evaluate the exposure of employees handling such casks, Monte Carlo radiation transport codes can be employed. Nevertheless, to assess the reliability of these codes and nuclear data, experimental checks are required. In this study, a neutron generator (NG) producing neutrons of 2.5 MeV was employed to simulate neutrons produced in spent nuclear fuel. Different configurations of shielding layers of steel and polyethylene were positioned between the target of the NG and a NE-213 detector. The results of the measurements of neutron and γ radiation and the corresponding simulations with the code MCNP6 are presented. Details of the experimental set-up as well as neutron and photon flux spectra are provided as reference points for such NG investigations with shielding structures.

EURADOS (European Radiation Dosimetry Group) Working Group 12 (dosimetry in medical imaging) established a subtask devoted to the dosimetry of the medical staff employed in interventional radiology practices. As it is widely known, such practices are characterized by high doses, with respect the other medical procedures, both for the patient and the radiologist. For interventional cardiology there are several publications concerning medical staff dosimetry, on the contrary, for interventional radiology, data are more limited. For that reason WG-12 decided to study the irradiation scenario, employing simplified anthropomorphic models (MIRD type) with Monte Carlo simulations, reconstructing some specific interventional radiology practices (PTC and TIPS). In these procedures, where the X-ray C-arm is mainly fixed in PA projection and the beam directed to the patient abdomen, the radiologist is next to the patient right side, in correspondence to the liver region. The usage of the ceiling shielding is not very frequent, due to the difficulties in positioning it between the radiation source (the X-ray and the patient as the scattering source) and the operator. The aim of the simulations program is: to evaluate the dose received by the radiologist, in a region simulating the presence of the dosemeter fixed on the lead apron at the breast level ; to estimate the corresponding effective dose ; to make a sensitivity analysis on different parameters affecting the calculated results (as the reciprocal position between the two operators, the beam quality and the X-ray field dimension). Indeed a particular attention is devoted to the eye lens dosimetry, that has become a “critical issue” for personnel dosimetry, after ICRP has reconsidered the radiation sensitivity of the lens of the eye. In the present work the general scheme, the assumptions and the followed methodology are presented with some very preliminary results of the simulations and the measurements.

Disposal in deep geological formations with arrangements for monitoring and retrieval has been considered as one of the most promising management concepts of heat-generating, high-level nuclear waste. Typical design of a deep geological repository requires a shielding cask containing the waste, which is in turn located underground in an emplacement drift of a host rock formation. Various rock types, such as rock salt, clay stone and granite, are possible candidates as host rock for a deep geological repository. The massive host rock formation around the emplacement drift is the most important barrier against radionuclide release into the biosphere. However, the host rock layers have also influence on the radiation field in the emplacement drift, which should be taken into account when assessing occupational exposure in the repository. In the current study, impact of two different materials, i.e. rock salt and concrete (building material of the supporting liner for a drift in clay stone or granite), on radiation field around a nuclear waste package disposed in an emplacement drift was investigated with Monte Carlo method. The high-level nuclear waste was simulated with a Cf-252 neutron source. Both neutron and gamma dose rates and spectra around the waste package were calculated. It was found out that neutrons dominate the radiation field in the drift and the dose rates in the drift are enhanced due to backscattered radiation by the surrounding material layers. Furthermore, due to different material compositions of rock salt and concrete, the resulted neutron spectra have also different characteristics. In general, concrete moderates neutrons better than rock salt, which leads to a lower dose rates in the emplacement drift.

Albedo neutron dosemeter is the German official personal neutron dosemeter in mixed radiation fields where neutrons contribute to personal dose. In deep geological repositories for high-level nuclear waste, where neutrons can dominate the radiation field, it is of interest to investigate the performance of albedo neutron dosemeter in such facilities. In this study, the deep geological repository is represented by a shielding cask loaded with spent nuclear fuel placed inside a rock salt emplacement drift. Due to the backscattering of neutrons in the drift, issues concerning calibration of the dosemeter arise. Field-specific calibration of the albedo neutron dosemeter was hence performed with Monte Carlo simulations. In order to assess the applicability of the albedo neutron dosemeter in a deep geological repository over a long time scale, spent nuclear fuel with different ages of 50, 100 and 500 years were investigated. It was found out, that the neutron radiation field in a deep geological repository can be assigned to the application area 'N1' of the albedo neutron dosemeter, which is typical in reactors and accelerators with heavy shielding.

In the operational phase of a deep geological disposal facility for high-level nuclear waste, the radiation field in the vicinity of a waste cask is influenced by the backscattered radiation of the surrounding walls of the emplacement drift. For a comparison of disposal of spent nuclear fuel in various host rocks, it is of interest to investigate the influence of the surrounding materials on the radiation field and the personal radiation exposure. In this generic study individual dosimetry of personnel involved in emplacement of casks with spent nuclear fuel in drifts in rock salt and in a clay formation was modelled.

The combination of fluoroscopically guided interventional procedures with computed tomography (CTF) has become widespread around the world. The benefits of CTF include the ability to obtain a real-time visualization of the entire body, increased target accuracy and improved visualization of biopsy needles. Modern CTF units work with variable frame rates for image selection, and therefore the dose distributions for patients and staff can considerably vary, creating growing concern in terms of the occupational exposure of interventionists and the drawback of a higher exposure of the patient. A literature review of the latest CTF publications is summarized in this article. A wide range of CTF studies reveal different treatment methods used in clinical practice, and therefore the differences in the exposures between them; as well as in the radiation protection tools and dose monitoring. Further optimization of radiation protection methods, harmonization of exposure patterns as well as training and education of CTF staff on the basis of the information in the survey, are strongly recommended.

In deep geological repositories for high-level nuclear waste, radiation field around the disposed nuclear waste package is characterized by highly scattered radiations due to the surrounding host rock layers or cement liner. Calculation of the reference level of the occupational radiation exposure in such a facility is hence of interest, since geometrical conditions of the occupational exposure in the facility cannot be readily represented by the standard irradiation geometries considered by ICRP. In this study, a horizontal emplacement drift inside rock salt was modeled to represent a deep geological disposal facility. A nuclear waste package, simulated with a shielding cask loaded with spent nuclear fuel, was placed on the ground of the rock salt drift. A "reference worker" inside the drift was represented by the ICRP/ICRU reference adult voxel phantom. The reference level of the occupational radiation exposure was then calculated with a Monte Carlo code in terms of the effective dose based on the ICRP 2007 recommendation. In order to investigate the occupational exposure of a worker during different working scenarios in the drift, the effective dose was calculated with the voxel phantom placed at various distances and different body orientations with respect to the shielding cask. Furthermore, the effective dose obtained with voxel phantom was compared with that obtained with the fluence-to-effective-dose conversion coefficients for the standard irradiation geometries provided by ICRP. It was found out that (1) usage of the dose conversion coefficients for the isotropic (ISO) geometry, which is recommended by ICRP for highly scattered radiation fields, generally underestimates the effective dose in the rock salt emplacement drift; (2) depending on the orientation of the worker in the drift, the dose conversion coefficients for the anterior-to-posterior (AP) or the rotational (ROT) geometry should be used, in order to obtain an adequate estimation of the effective dose in the rock salt drift. (C) 2017 Elsevier Ltd. All rights reserved.

Studies have shown that there is high radiation exposure to medical staff during computed tomography fluoroscopy (CTF)-guided procedures. This study aims to investigate staff dose reduction techniques considering the CTF gantry positioning in the room and room dimensions in addition to the conventional use of thyroid collars, aprons and eye goggles. A Toshiba Aquilion One 640 slice CT scanner and CTF room were modelled using SimpleGeo. Standing and supine adult mesh phantoms were used to represent the staff and patient. The models were spatially put together on one platform using VOXEL2MCNP. Based on this, MCNPX input files were generated for the studies. CTF gantry and staff positions, and CTF room size were varied for different scenarios. Effective, eye lens and thyroid dose to staff were estimated for each scenario. Additional means of possible dose reduction with respect to positioning of the CTF device and room layout are discussed.

Difficult building conditions but also the impairment of the cityscape through overhead lines can lead to high cost and lack of acceptance from citizens and town planners. In these cases the use of a tram with an energy storage (ES) which enables for catenary free operation (CFO) could be the more cost-effective solution and could create the necessary acceptance. This article presents the operational concept of catenary free operation of a tram and the integration of a Lithium-Ion (Li-Ion) energy storage into the propulsion system of a BOMBARDIER* FLEXITY* 2 tram. The first application of this propulsion system was carried out for the newly built tram line of the Chinese metropolis of Nanjing. The trams are successfully in passenger operation since the youth Olympic Games in August 2014, running without catenaries on 90% of the line.