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[en] The IRIS (International Reactor Innovative and Secure) reactor design is being developed by an international consortium of 21 organizations from ten countries, including three members from Brazil and one from Mexico. This reflects the interest that Latin America has for a project which addresses the energy needs of the region. Presented here are some of the most recent developments in the IRIS project. The project's highest priority is the current pre-application licensing with the US NRC, which has required an investigation of the major accident sequences and a preliminary probabilistic risk assessment (PRA). The results of the accident analyses confirmed the outstanding inherent safety of the IRIS configuration and the PRA analyses indicated a core damage frequency due to internal events of the order of 2E-8. This not only highlights the enhanced safety characteristic of IRIS which should enhance its public acceptance, but it has also prompted IRIS to consider the possibility of being licensed without the need for off-site emergency response planning which would have a very positive economic implication. The modular IRIS, with each module rated at ∼ 335 MWe, is of course an ideal size for developing countries as it allows to easily introduce a moderate amount of power on limited electric grids. IRIS can be deployed in single modules in regions only requiring a few hundred MWs or in multiple modules deployed successively at time intervals in large urban areas requiring a larger amount of power increasing with time. IRIS is designed to operate ''hands-off'' as much as possible, with a small crew, having in mind deployment in areas with limited infrastructure. Thus IRIS has a 48-months maintenance interval, long refueling cycles in excess of three years, and is designed to increase as much as possible operational reliability. For example, the project has recently adopted internal control rod drive mechanisms to eliminate vessel head penetrations and the possibility of corrosion cracking as in Davis-Besse and other plants. Latin America, as many other regions on the earth, needs water as much as electricity. IRIS has developed a water desalination co-generation design which can employ a variety of processes as dictated by local and economic conditions. Applications to the arid Brazilian Nord-Este and Mexican Nord-Oeste are being considered

[en] Globally, karst aquifers are one of the most significant sources of drinking water. Although characterized by variable regimes, karst groundwater has excellent natural quality. The main prerequisite for successful utilization and management of karst groundwater is the proper evaluation and characterization of a karst hydrogeological system. It is very important to define the hydrogeological parameters of a system, its boundaries, and the amount of groundwater that could be sustainably used. Delineation of the catchment area is one of the most complicated tasks in karst aquifer characterization, but it is necessary when it comes to the definition of sanitary protection zones. Due to high seasonal fluctuation of groundwater tables, it is very common in a highly karstified area to discover reorientation of the groundwater flow and the changes of the basin’s boundaries. The catchment area of a karst aquifer usually consists of an autogenic and an allogenic part of the recharge area, where the former is consistently very difficult to identify. This article discusses a case of inverse definition of karst spring catchment boundaries based on water budget and systematic measurements of spring discharge and precipitation. The studied area covers the karst spring Vučkovo vrelo, located in the vicinity of the city of Sjenica in SW Serbia. The catchment area at the karstic Pešter Plateau consists of Triassic limestone and dolomites (autogenic recharge), which are in some areas partly covered by Jurassic ophiolites and Miocene sediments. The karst spring discharge rate has been monitored since 2016, while precipitation data has been collected since 1950s. On average, at this spring, the karst aquifer annually drains a total water amount of 7.9 x 106 m3, while the sum of the annual rainfall in an average hydrological year for the concerned period is 850 l/m2. Some water budget components are approximated by necessity, or values have been used by analogy. Such is the case with effective infiltration (Ief), which is estimated to be 55% of the rainfall on average. This value resulted from calculated evapotranspiration of 35%, based on Turc’s equation, with an estimated runoff of 10%. At the Vučkovo vrelo spring, this approach resulted in the catchment size of approximately 15 km2, which, in the field has been found to indeed correspond to the suggested the sanitary zone no. 3 (the zone of observation according to the national legislation). Considering that karst spring is of ascending type, with a very stable discharge in the course of a hydrologic year, it is assumed that boundaries of its catchment area are not changing considerably throughout the year. Nevertheless, continuous monitoring of karst spring discharge and precipitation would provide a basis for more precise delineation of the catchment area as an iterative process.

[en] The paper presents data about the ⁴⁰K activity level, i.e. the concentration of K, in different feeds that are used in the intensive poultry production. Also, radiation burden to which poultry is exposed by ⁴⁰K is estimated. The ⁴⁰K activity level to which broilers and laying hens are exposed during intensive husbandry depends on the kind of feed. Broilers receive least ⁴⁰K activity of they are fed on oats. The laying hens are two times more burdened by ⁴⁰K activity than broilers, regardless of the type of feed. In their lifetimes broilers take up ten times less ⁴⁰K than laying hens. These results rise the question whether ⁴⁰K has a radiobiological effect on the poultry organism, having in mind the level of activity of this radionuclide to which poultry is exposed. (Author)

[en] The paper describes the tasks and field of activity of veterinary specialists for radiation control of animals and animal production. The education process of veterinary specialists for the work on this field is also presented. Curriculums in the field of radiation hygiene of the animal production at veterinary faculties in our country comprise this matter as a separated one term subject. At undergraduate level teaching is accompanied by appropriate practical exercises. In this way a good basis for postgraduate improvement of students through master degrees of specialization is provided. An important role in the education of veterinary specialists in the field of radiation protection and radiation control of animal production play special seminars and courses for innovation and mastering of new working methods. Practical work and exercises in various field are so designed as to enable students to master completely the foreseen matter. Such a developed system for education of veterinary personnel furnished a personnel basis for development of radition hygienic monitoring system of animal products. (Author)

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[en] IRIS is an advanced pressurized water reactor of integral configuration. This integral configuration with its relatively large reactor vessel and thick downcomer (1.7 m) results in a significant reduction of radiation field and material activation. It thus enables setting up aggressive dose reduction objectives, but at the same time presents challenges for the shielding analysis which needs to be performed over a large spatial domain and include flux attenuation by many orders of magnitude. The Monte Carlo method enables accurately representing irregular geometry and potential streaming paths, but may require significant computational efforts to reduce statistical uncertainty within the acceptable range. Variance reduction methods do exist, but they are designed to provide results for individual detectors and in limited regions, whereas in the scoping phase of IRIS shielding analysis the results are sought throughout the whole containment. To facilitate such analysis, the SCALE MAVRIC was employed. Based on the recently developed FW-CADIS method, MAVRIC uses forward and adjoint deterministic transport theory calculations to generate effective biasing parameters for Monte Carlo simulations throughout the problem. Previous studies have confirmed the potential of this method for obtaining Monte Carlo solutions with acceptable statistics over large spatial domains. The objective of this work was to evaluate the capability of the FW-CADIS/MAVRIC to efficiently perform the required shielding analysis of IRIS. For that purpose, a representative model was prepared, retaining the main problem characteristics, i.e., a large spatial domain (over 10 m in each dimension) and significant attenuation (over 12 orders of magnitude), but geometrically rather simplified. The obtained preliminary results indicate that the FW-CADIS method implemented through the MAVRIC sequence in SCALE will enable determination of radiation field throughout the large spatial domain of the IRIS nuclear power plant within acceptable computational efforts.(author)

[en] An innovative method has been demonstrated for separating alpha-emitting isotopes for medical radiotherapy applications. The method relies on recoil-ion separation rather than on conventional wet chemistry techniques to separate medical isotopes from their precursor sources. The isotopes ²²⁵Ac and ²¹³Bi have been separated from electro-deposited sources of ²²⁹ThO₂. Separations of ²²⁵Ac were carried out by placing nickel recoil collector foils in firm contact with the ²²⁹ThO₂ sources. One-stage recoil-ion separations of ²²⁵Ac from ²²⁹Th have been performed as well as two-stage separations of ²¹³Bi from previously recoil separated ²²⁵Ac. In addition, a direct recoil separation of ²¹³Bi from ²²⁹Th has been demonstrated. The ²¹³Bi from the one-stage direct separation has a high isotopic purity, but contains small amounts of long-lived ²²⁵Ac alpha activity. The two-stage separations of ²¹³Bi produce high isotopic purity material (>99.9999%), but result in lower isotopic yields. Range-energy calculations have been carried out to determine the yields of recoil ions as a function of alpha-particle energy and ThO₂ thickness. The results of the calculations have been benchmarked with recoil separation measurements carried out using ThO₂ electro-deposits over a range of thickness. A computer code based on the generalized Bateman equations has been developed to allow calculations of the amounts of any isotope in the ²²⁹Th decay chain as a function of recoil separation exposure time and elapsed time after the separation. An excellent match has been obtained between the predictions of the Bateman calculations and the results of recoil separation measurements. The recoil separation method has proven to be a simple and effective way of separating medically useful isotopes such as ²¹³Bi. In addition, the method has been shown to produce no chemical or radioactive wastes, in contrast to radiochemical separation methods, which generate mixed (chemical and radioactive) waste