Impact radiologique liés au transport de matières radioactives par route en Espagne / Radiological impact associated with the transport by road of radioactive material in Spain

Questions relating to the transport of radioactive materials are very much an issue of current interest due to the increasing mobility of the materials involved in the nuclear fuel cycle, commitment to the environment, the safety and protection of persons and the corresponding regulatory legal framework. The radiological impact associated with this type of transport was assessed by means of a new data-processing tool that may be of use and serve as complementary documentation to that included in transport regulations. Thus, by determining the level of radiation at a distance of one metre from the transport vehicle and by selecting a route, the associated impacts will be obtained, such as the affected populations, the dose received by the most highly exposed individual, the overall radiological impact, the doses received by the population along the route and the possible detriment to their health. The most important conclusion is that the emissions of ionising radiation from the transport of radioactive material by road in Spain are not significant as regards the generation of adverse effects on human health, and that their radiological impact may be considered negligible.

¿Impact from road transport of radioactive wastes in Spain?

Transports of radioactive wastes in Spain are becoming issues of renewed interest, due to the increased mobility of these materials which can be expected after the building and operation of the planned central repository for this country in a near future. Such types of residues will be mainly of the medium and high activity classes and have raised concerns on the safety of the operations, the radiological protection of the individuals, the compliance with the legal regulations and their environmental consequences of all kind. In this study, relevant information for the assessment of radiological risk of road transport were taken into account, as the sources and destination of the radioactive transports, the amount of traveling to be done, the preferred routes and populations affected, the characterization of the residues and containers, their corresponding testing, etc. These data were supplied by different organizations fully related with these activities, like the nuclear power stations, the companies in charge of radioactive transports, the enterprises for inspection and control of the activities, etc., as well as the government institutions which are responsible for the selection and location of the storage facility and other decisions on the nuclear policies of the country. Thus, we have developed a program for computing the data in such a form that by entering the radiation levels at one meter of the transport loads and by choosing a particular displacement, the computer application is capable to calculate the corresponding radiological effects, like the global estimated impact, its relevance to the population in general or on those people living and driving near the main road routes, the doses received by the most exposed individuals (e.g. the workers for loading or driving the vehicle), or the probability of detrimental on the human health. The results of this work could be of help for a better understanding and management of these activities and their related impacts; at the same time that the generated reports of the computer application are considered of particular interest as innovative and complementary information to the current legal documentation, which is basically required for transporting radioactive wastes in the country, according with the international safety rules (like IAEA and ADR).Though main studies are still in progress, as the definite location for the Spanish storage facility has not been decided yet, preliminary results with the existing transports of residues of medium activity indicate that the radiological impact is very low in conventional operations. Nevertheless, the management of these transports is complex and laborious, making it convenient to progress further in the analysis and quantification of this kind of events, which constitutes one of the main objectives of the present study for the radioactive road mobility in Spain.

Atmospheric modelling of tritium forms transport: review of capabilities and R&D needs for the assessment of fusion facilities environmental impact

One of the key scrutiny issues of new coming energy era would be the environmental impact of fusion facilities managing one kg of tritium. The potential change of committed dose regulatory limits together with the implementation of nuclear design principles (As Low as Reasonably achievable - ALARA -, Defense in Depth -D-i-D-) for fusion facilities could strongly impact on the cost of deployment of coming fusion technology. Accurate modeling of environmental tritium transport forms (HT, HTO) for the assessment of fusion facility dosimetric impact in Accidental case appears as of major interest. This paper considers different short-term releases of tritium forms (HT and HTO) to the atmosphere from a potential fusion reactor located in the Mediterranean Basin. This work models in detail the dispersion of tritium forms and dosimetric impact of selected environmental patterns both inland and in-sea using real topography and forecast meteorological data-fields (ECMWF/FLEXPART). We explore specific values of this ratio in different levels and we examine the influence of meteorological conditions in the HTO behavior for 24 hours. For this purpose we have used a tool which consists on a coupled Lagrangian ECMWF/FLEXPART model useful to follow real time releases of tritium at 10, 30 and 60 meters together with hourly observations of wind (and in some cases precipitations) to provide a short-range approximation of tritium cloud behavior. We have assessed inhalation doses. And also HTO/HT ratios in a representative set of cases during winter 2010 and spring 2011 for the 3 air levels.

Analysis of a Spanish energy scenario with Generation IV nuclear reactors

The advantages of fast-spectrum reactors consist not only of an efficient use of fuel through the breeding of fissile material and the use of natural or depleted uranium, but also of the potential reduction of the amount of actinides such as americium and neptunium contained in the irradiated fuel. The first aspect means a guaranteed future nuclear fuel supply. The second fact is key for high-level radioactive waste management, because these elements are the main responsible for the radioactivity of the irradiated fuel in the long term. The present study aims to analyze the hypothetical deployment of a Gen-IV Sodium Fast Reactor (SFR) fleet in Spain. A nuclear fleet of fast reactors would enable a fuel cycle strategy different than the open cycle, currently adopted by most of the countries with nuclear power. A transition from the current Gen-II to Gen-IV fleet is envisaged through an intermediate deployment of Gen-III reactors. Fuel reprocessing from the Gen-II and Gen-III Light Water Reactors (LWR) has been considered. In the so-called advanced fuel cycle, the reprocessed fuel used to produce energy will breed new fissile fuel and transmute minor actinides at the same time. A reference case scenario has been postulated and further sensitivity studies have been performed to analyze the impact of the different parameters on the required reactor fleet. The potential capability of Spain to supply the required fleet for the reference scenario using national resources has been verified. Finally, some consequences on irradiated final fuel inventory are assessed. Calculations are performed with the Monte Carlo transport-coupled depletion code SERPENT together with post-processing tools.

Overview of the Spanish Fuel Cycle: Technical Tours Organized by Spanish young Generation in Nuclear.

Spanish Young Generation in Nuclear (Jóvenes Nucleares, JJNN) is a non-profrt organization that depends on the Spanish Nuclear Society (Sociedad Nuclear Española, SNE).Since one of rts main goals is to spread the knowledge about nuclear power,severa! technical tours to facilities wrth an importan!role in the nuclear fuel cycle have been organized for the purpose ofleaming about the different stages of the Spanish tuel cycle. Spanish Young Generation in Nuclear had the opportunity to visit ENUSA Fuel Assembly Factory in Juzbado (Salamanca, Spain), Where it could be understood the front-end cycle which involves the uranium supply and storage, design and manufacturing of fuel bundles for European nuclear power plants. Alterwards, due to the tour of Almaraz NPP (PWR) and Santa María de Garoña NPP (BWR), rt could be comprehended how to obtain energy from this fuel in two different types of reactors.Furthermore,in these two plants, the facilities related to the back-end cycle could be toured. lt was possible to watch the Spent FuelPools, where the fuel bundles are stored under water until their activity is reduced enough to transport them to an Individual Temporary Storage Facility orto the Centralized Temporary Storage. Finally, a technical tour to ENSA Heavy Components Factory (ENSA) was accomplished, Where it could be experienced at first hand how different Nuclear Steam Supply System (NSSS) components and other nuclear elements, such as racks or shipping and storage casks for spent nuclear fuel, are manulactured. All these perlonned technical tours were a complete success thanks to a generous care and know-how of the wor1

Modelización y validación experimental del transporte de tritio en metal líquido y otros materiales para reactores de fusión nuclear magnética e inercial

La presente tesis se centra en el estudio de los fenómenos de transporte de los isótopos de hidrógeno, y más concretamente del tritio, en materiales de interés para los reactores de fusión nuclear. Los futuros reactores de fusión nuclear necesitarán una Planta de Tritio, con una envoltura regeneradora (breeding blanket) y unos sistemas auxiliares claves para su diseño. Por lo tanto su desarrollo y cualificación son cruciales para demostrar que los reactores de fusión son una opción viable como futura fuente de energía. Se han resaltado los diferentes retos de la difusión y retención de estas especies ligeras para cada sistema de la Planta de Tritio, y se han identificado las necesidades experimentales y paramétricas para abordar las simulaciones de difusión, como factores de transporte como la difusividad, absorción/desorción, solubilidad y atrapamiento. Se han estudiado los fenómenos de transporte y parámetros del T en el metal líquido LiPb, componente del breeding blanket tanto para una planta de fusión magnética como inercial. Para ello se han utilizado dos experimentos con características diversas, uno de ellos se ha llevado a cabo en un reactor de alto flujo, y por lo tanto, en condiciones de irradiación, y el otro sin irradiación. Los métodos de simulación numérica aplicados se han adaptado a los experimentos para las mediciones y para estudiar el régimen de transporte. En el estudio de estos experimentos se ha obtenido un valor para algunos de los parámetros claves en el transporte y gestión del tritio en el reactor. Finalmente se realiza un cálculo de la acumulación y difusión de tritio en una primera pared de tungsteno para un reactor de fusión inercial. En concreto para el proyecto de fusión por láser europeo, HiPER (para sus fases 4a y 4b). Se ha estudiado: la implantación de los isótopos de H y He en la pared de W tras una reacción de fusión por iluminación directa con un láser de 48MJ; el efecto en el transporte de T de los picos de temperatura en el W debido a la frecuencia de los eventos de fusión; el régimen de transporte en la primera pared. Se han identificado la naturaleza de las trampas más importantes para el T y se ha propuesto un modelo avanzado para la difusión con trampas. ABSTRACT The present thesis focuses into study the transport phenomenons of hydrogen isotopes, more specifically tritium, in materials of interest for nuclear fusion reactors. The future nuclear reactors will be provided of a Tritium Plant, with its breeding blanket and its auxiliary systems, all of them essential components for the plant. Therefore a reliable development and coalification are key issues to prove the viability of the nuclear fusion reactors as an energy source. The currently challenges for the diffusion and accumulation of these light species for each system of the TP has been studied. Experimental and theoretical needs have been identified and analyzed, specially from the viewpoint of the parameters. To achieve reliable simulations of tritium transport, parameters as diffusivity, absorption/desorption, solubility and trapping must be reliables. Transport phenomenon and parameters of T in liquid metal have been studied. Lead lithium is a key component of the breeding blanket, either in magnetic or inertial fusion confinement. Having this aim in mind, two experiments with different characteristics have been used; one of them has been realized in a high flux reactor, and hence, under irradiation conditions. The other one has been realized without radiation. The mathematical methods for the simulation have been adapted to the experiments, for the measures and also to study the transport behavior. A value for some key parameters for tritium management has been obtained in these studies. Finally, tritium accumulation and diffusion in a W first wall of an inertial nuclear fusion reactor has been assessed. A diffusion model of the implanted H, D, T and He species for the two initial phases of the proposed European laser fusion Project HiPER (namely, phase 4a and phase 4b) has been implemented using Tritium Migration Analysis Program, TMAP7. The effect of the prompt and working temperatures and the operational pulsing modes on the diffusion are studied. The nature of tritium traps in W and their performance has been analyzed and discussed.