Adecuación del código SPARC90 para la simulación de la captura de aerosoles por rotura en el generador de vapor

Ponencia acerca de la mejora del cálculo del factor de descontaminación, que cuantifica el valor del cociente entre el flujo másico de entrada y salida de aerosoles durante la fase de expansión del chorro gaseoso que desplaza al líquido de un lecho de agua. Los mecanismos de captura de SPARC90 se han revisado, proponiéndose mejoras que se han introducido en el propio código con el objeto de obtener mejoras significativas en las predicciones. ARTIST2Escrivá Castells, FA.; Muñoz-Cobo González, JL.; Berna Escriche, C.; Herranz, L. (2011). Adecuación del código SPARC90 para la simulación de la captura de aerosoles por rotura en el generador de vapor. Sociedad Nuclear Española. http://hdl.handle.net/10251/71477

Desarrollo de Nuevas Correlaciones para Flujo Anular

El presente trabajo explora la extensa literatura existente y propone nuevas correlaciones para el estudio del flujo anular. El interés de este trabajo se centra, por una parte, en la recopilación de la dispersa y abundante información existente y, por otra parte, en el desarrollo de nuevas correlaciones para la determinación de las principales magnitudes que caracterizan al flujo anular a partir de datos experimentales encontrados en la literatura abiertaBerna Escriche, C.; Escrivá Castells, FA.; Muñoz-Cobo González, JL.; Herranz, L. (2013). Desarrollo de Nuevas Correlaciones para Flujo Anular. Sociedad Nuclear Española. http://hdl.handle.net/10251/71612

Influence of chronic ocular hypertension on emmetropia: Refractive, structural and functional study in two rat models

Chronic ocular hypertension (OHT) influences on refraction in youth and causes glaucoma in adulthood. However, the origin of the responsible mechanism is unclear. This study analyzes the effect of mild-moderate chronic OHT on refraction and neuroretina (structure and function) in young-adult Long-Evans rats using optical coherence tomography and electroretinography over 24 weeks. Data from 260 eyes were retrospectively analyzed in two cohorts: an ocular normotension (ONT) cohort (20 mmHg), in which OHT was induced either by sclerosing the episcleral veins (ES group) or by injecting microspheres into the anterior chamber. A trend toward emmetropia was found in both cohorts over time, though it was more pronounced in the OHT cohort (p < 0.001), especially in the ES group (p = 0.001) and males. IOP and refraction were negatively correlated at week 24 (p = 0.010). The OHT cohort showed early thickening in outer retinal sectors (p < 0.050) and the retinal nerve fiber layer, which later thinned. Electroretinography demonstrated early supranormal amplitudes and faster latencies that later declined. Chronic OHT accelerates emmetropia in Long–Evans rat eyes towards slowly progressive myopia, with an initial increase in structure and function that reversed over time. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Chronic glaucoma using biodegradable microspheres to induce intraocular pressure elevation. Six-month follow-up

Background: To compare two prolonged animal models of glaucoma over 24 weeks of follow-up. A novel pre-trabecular model of chronic glaucoma was achieved by injection of biodegradable poly lactic-co-glycolic acid (PLGA) microspheres (10–20 µm) (Ms20/10) into the ocular anterior chamber to progressively increase ocular hypertension (OHT). Methods: Rat right eyes were injected to induce OHT: 50% received a suspension of Ms20/10 in the anterior chamber at 0, 2, 4, 8, 12, 16 and 20 weeks, and the other 50% received a sclerosing episcleral vein injection biweekly (EPIm). Ophthalmological clinical signs, intraocular pressure (IOP), neuroretinal functionality measured by electroretinography (ERG), and structural analysis of the retina, retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) protocols using optical coherence tomography (OCT) and histological exams were performed. Results: Both models showed progressive neuroretinal degeneration (p < 0.05), and contralateral eye affectation. The Ms20/10 model showed a more progressive increase in IOP and better preservation of ocular surface. Although no statistical differences were found between models, the EPIm showed a tendency to produce thicker retinal and thinner GCL thicknesses, slower latency and smaller amplitude as measured using ERG, and more aggressive disturbances in retinal histology. In both models, while the GCL showed the greatest percentage loss of thickness, the RNFL showed the greatest and earliest rate of thickness loss. Conclusions: The intracameral model with biodegradable microspheres resulted more like the conditions observed in humans. It was obtained by a less-aggressive mechanism, which allows for adequate study of the pathology over longer periods. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

RICORS2040 : The need for collaborative research in chronic kidney disease

Chronic kidney disease (CKD) is a silent and poorly known killer. The current concept of CKD is relatively young and uptake by the public, physicians and health authorities is not widespread. Physicians still confuse CKD with chronic kidney insufficiency or failure. For the wider public and health authorities, CKD evokes kidney replacement therapy (KRT). In Spain, the prevalence of KRT is 0.13%. Thus health authorities may consider CKD a non-issue: very few persons eventually need KRT and, for those in whom kidneys fail, the problem is 'solved' by dialysis or kidney transplantation. However, KRT is the tip of the iceberg in the burden of CKD. The main burden of CKD is accelerated ageing and premature death. The cut-off points for kidney function and kidney damage indexes that define CKD also mark an increased risk for all-cause premature death. CKD is the most prevalent risk factor for lethal coronavirus disease 2019 (COVID-19) and the factor that most increases the risk of death in COVID-19, after old age. Men and women undergoing KRT still have an annual mortality that is 10- to 100-fold higher than similar-age peers, and life expectancy is shortened by ~40 years for young persons on dialysis and by 15 years for young persons with a functioning kidney graft. CKD is expected to become the fifth greatest global cause of death by 2040 and the second greatest cause of death in Spain before the end of the century, a time when one in four Spaniards will have CKD. However, by 2022, CKD will become the only top-15 global predicted cause of death that is not supported by a dedicated well-funded Centres for Biomedical Research (CIBER) network structure in Spain. Realizing the underestimation of the CKD burden of disease by health authorities, the Decade of the Kidney initiative for 2020-2030 was launched by the American Association of Kidney Patients and the European Kidney Health Alliance. Leading Spanish kidney researchers grouped in the kidney collaborative research network Red de Investigación Renal have now applied for the Redes de Investigación Cooperativa Orientadas a Resultados en Salud (RICORS) call for collaborative research in Spain with the support of the Spanish Society of Nephrology, Federación Nacional de Asociaciones para la Lucha Contra las Enfermedades del Riñón and ONT: RICORS2040 aims to prevent the dire predictions for the global 2040 burden of CKD from becoming true

In-containment source term: Key insights gained from a comparison between the PHEBUS-FP programme and the US-NRC NUREG-1465 revised source term

NUREG-1465 was a major change to the preceding figures defining in-containment source term. Since then, the most important research venture in the arena of severe accidents has been the PHEBUS-FP project. Experimental data and interpretations brought in along the course of the project have highlighted similarities and discrepancies with those insights given in the NUREG-1465. This paper sets comparisons between NUREG-1465 and PHEBUS-FP in three key aspects: the release of radionuclides into containment, the in-containment aerosol behaviour and, finally, iodine chemical behaviour in the containment. The experimental basis of discussions is the FPT0, FPT1, FPT2 and FPT3 series, although the latter cannot be openly addressed yet. Similarities have been found regarding qualitative gap and early in-vessel releases, quantitative net release of noble gases and iodine releases, dominance of sedimentation as natural removal mechanism for in-containment aerosols, etc. Nonetheless, PHEBUS-FP data have also drawn attention to major discrepancies with respect to NUREG-1465. Examples are cesium and tellurium releases and possible massive iodine release under specific conditions. But, in addition, PHEBUS-FP has brought new insights, such as potential formation of in-sump iodine precipitates or the need of revisiting NUREG-1465 element grouping. © 2009 Elsevier Ltd. All rights reserved

In-containment source term in accident conditions in sodium-cooled fast reactors Data needs and model capabilities

International audienceSodium-cooled fast reactors (SFRs) are one out of the six technologies considered in the so-called Generation IV initiative. A full-scope safety analysis of this reactor type would need to have computation tools developed and properly validated. The present paper focuses on the review of currently available data and modeling capabilities for in-containment source term analysis in accident conditions. Generally speaking, it has been found that improvements to characterizing particles (i.e., density and shape) and particle-particle interaction processes are required. However, beyond any doubt, two of the strongest modeling needs for SFR accidents are aerosol generation which, in turn, means to properly model sodium vaporization, chemical reactions with the surrounding gas, nucleation of combustion products and primary particle agglomeration; and fission products partitioning. Current LWR integral codes, although not yet furnished with such models, look promising as a computational platform to be extended to the SFR domain. In any case, once they are adapted to anticipated SFR scenarios, extensive validation should be undertaken against a comprehensive and sound database. © 2011 Elsevier Ltd. All rights reserved

Recent advances in the source term area within the SARNET European severe accident research network

International audienceSource Term has been one of the main research areas addressed within the SARNET network during the 7th EC Framework Programme of EURATOM. The entire source term domain was split into three major areas oxidising impact on source term, iodine chemistry in the reactor coolant system and containment and data and code assessment. The present paper synthesises the main technical outcome stemming from the SARNET FWP7 project in the area of source term and includes an extensive list of references in which deeper insights on specific issues may be found. Besides, based on the analysis of the current state of the art, an outlook of future source term research is outlined, where major changes in research environment are discussed (i.e., the end of the Phébus FP project; the end of the SARNET projects; and the launch of HORIZON 2020). Most probably research projects will be streamlined towards release and transport under oxidising conditions, containment chemistry, existing and innovative filtered venting systems and others. These will be in addition to a number of projects that have been completed or are ongoing under different national and international frameworks, like VERDON, CHIP and EPICUR started under the International Source Term Programme (ISTP), the OECD/CSNI programmes BIP, BIP2, STEM, THAI and THAI2, and the French national programme MIRE. The experimental PASSAM project under the 7th EC Framework programme, focused on source term mitigation systems, is highlighted as a good example of a project addressing potential enhancement of safety systems based on already available knowledge. © 2015 Elsevier B.V. All rights reserved

Comparison of LWR and SFR in-containment source term: Similarities and differences

The fundamental differences between Light-Water Reactors (LWRs) and Sodium Fast Reactors (SFRs) (i.e., breeding ratio, neutron energy spectrum, power densities, coolant nature, reactor architecture and so on) entail major differences in safety aspects. In particular, the in-containment source terms in the event of a severe accident differ in major ways. Nevertheless, an in-depth analysis of similarities and differences based on the present available knowledge should allow assessment of the applicability of LWR safety-analysis tools to the SFR domain. This is the final goal of this paper. A thorough literature review indicates that the capabilities of present LWR safety-analysis codes to address in-containment SFR accident scenarios are uneven for different areas: while they appear acceptable for predicting aerosol evolution, they require significant expansion in other areas like aerosol generation and fission-product partitioning. Additionally, some areas in need of further experimental research are highlighted in this paper. © 2013 Elsevier B.V. All rights reserved

Modeling liquid-gas iodine mass transfer under evaporative conditions during severe accidents

During postulated severe accidents transfer of volatile iodine dissolved in containment water sumps to atmosphere can be fostered under pool evaporative conditions. Scarcity of representative data has resulted in semi-empirical models that relies on fitting parameters and still need of further validation. This paper presents a mechanistic model based on: the two-film model, the heat-mass transfer analogy and the surface renewal theory. Comparison to data from the SISYPHE program, performed at the French "Institut de Radioprotection et de Sûreté Nucléaire", has resulted in an accurate response, the error band being 9-25% for the aqueous steady state concentration. Likewise, the model performance has been compared to the model implemented in the ASTEC code. In addition to yield similar results, some advantages have been highlighted: the mechanistic nature, the estimates conservatism, and the thorough documentation of model grounds and assumptions. © 2009 Elsevier B.V. All rights reserved