Influence of termal fluctuations in radiation damage cascade production and defect dynamics in tungsten

The detailed study of the deterioration suffered by the materials of the components of a nuclear facility, in particular those forming part of the reactor core, is a topic of great interest which importance derives in large technological and economic implications. Since changes in the atomic-structural properties of relevant components pose a risk to the smooth operation with clear consequences for security and life of the plant, controlling these factors is essential in any development of engineering design and implementation. In recent times, tungsten has been proposed as a structural material based on its good resistance to radiation, but still needs to be done an extensive study on the influence of temperature on the behavior of this material under radiation damage. This work aims to contribute in this regard. Molecular Dynamics (MD) simulations were carried out to determine the influence of temperature fluctuations on radiation damage production and evolution in Tungsten. We have particularly focused our study in the dynamics of defect creation, recombination, and diffusion properties. PKA energies were sampled in a range from 5 to 50 KeV. Three different temperature scenarios were analyzed, from very low temperatures (0-200K), up to high temperature conditions (300-500 K). We studied the creation of defects, vacancies and interstitials, recombination rates, diffusion properties, cluster formation, their size and evolution. Simulations were performed using Lammps and the Zhou EAM potential for

IFE Plant Technology Overview and contribution to HiPER proposal

HiPER is the European Project for Laser Fusion that has been able to join 26 institutions and signed under formal government agreement by 6 countries inside the ESFRI Program of the European Union (EU). The project is already extended by EU for two years more (until 2013) after its first preparatory phase from 2008. A large work has been developed in different areas to arrive to a design of repetitive operation of Laser Fusion Reactor, and decisions are envisioned in the next phase of Technology Development or Risk Reduction for Engineering or Power Plant facilities (or both). Chamber design has been very much completed for Engineering phase and starting of preliminary options for Reactor Power Plant have been established and review here

INCEFA-SCALE (INcreasing Safety in NPPs by Covering Gaps in Enviro Assessment-Focusing on Gaps between Laboratory Data and Component-SCALE)

RESUMEN: INCENFA-SCALE es un proyecto de cinco años financiado por el programa Horizonte 2020 de la Comisión Europea,sucesor del proyecto INCEFA-PLUS. El objetivo de este proyecto es mejorar la capacidad para pronosticar la vida útil de los componentes de centrales nucleares sometidos a fatiga asistida por el ambiente. EPRI está llevando a cabo una serie de ensayos de fatiga ambiental a escala de componente, que se espera que avancen significativamente en la disponibilidad de datos. Sin embargo, la capacidad de abordar la aplicabilidad de los datos de ensayos en laboratorio a componentes con geometría y cargas reales sigue estando restringida por el limitado número de datos. Este déficit de conocimiento es abordado por INCEFA-SCALE mediante: 1) la comprensión mecánica mediante un examen detallado de probetas ensayadas a fatiga y análisis de datos (INCEFA-PLUS, USNRC, EPRI, MHI y AdFaM); 2) ensayos centrados en aspectos particulares de las cargas cíclicas aplicadas a componentes. En paralelo, se llevará a cabo una campaña de ensayos para cubrir las necesidades detectadas. Finalmente, el proyecto proporcionará una guía para aplicar en componentes a escala real los datos obtenidos en laboratorio. Este artículo describe los antecedentes del proyecto y los avances realizados en el análisis de datos, comportamiento mecánico y necesidades de ensayo.ABSTRACT: INCENFA-SCALE is a five-year project funded by the EC Horizon2020 programme, successor of the INCEFA-PLUS project. INCEFA-SCALE started in October 2020. The objective of this project is to improve the ability of predicting the lifetime of NPPs components subjected to environmental assisted fatigue. EPRI is developing a series of component-scale environmental fatigue tests, which are expected to significantly advance data availability. However, the ability to address the applicability of laboratory test data to components with real geometry and loads remains restricted by the limited number of data. INCEFA-SCALE addressed this knowledge gap by: 1) developing a comprehensive mechanical understanding through detailed examination of fatigue-tested specimens and data analysis (INCEFA-PLUS, USNRC, EPRI, MHI and AdFaM); 2) conducting tests focused on particular aspects of cyclical loads applied to components. At the same time, a test campaign will be carried out to cover the detected needs. Finally, the project will provide a guidance for using the laboratory data in full-scale components. This article describes the background of the project and the advances made in data analysis, mechanical understanding and testing needs.Este proyecto ha recibido financiación del programa de investigación y formación de Euratom 2019-2020, bajo el acuerdo de subvención nº 945300. También se reconoce la significativa contribución de los miembros del proyecto INCEFA-SCALE

INCEFA-SCALE (Increasing Safety in NPPs by Covering Gaps in Environmental Fatigue Assessment - Focusing on Gaps Between Laboratory Data and Component-Scale)

INCEFA-SCALE is a five-year project supported by the European Commission HORIZON 2020 programme. INCEFA-SCALE kicked off in October 2020 and is the successor to the INCEFA-PLUS programme that ran from 2015 to 2020. The objective is to continue working towards advancing the ability to predict lifetimes of Nuclear Plant components when subjected to Environmentally Assisted Fatigue (EAF) loading Nuclear Plant operators have generally observed that the number of failure events attributable to EAF are fewer than predicted by current assessment methodologies. It is internationally recognised that a contributor to this discrepancy is the transferability of data from laboratory-scale tests to real nuclear components. This is the main knowledge gap addressed by INCEFA-SCALE. The project strategy will be (1) the development of mechanistic understanding developed through detailed examination of test specimens and data mining from large fatigue datasets, and (2) testing and analysis focussed on aspects and features of component-scale cyclic loading. The project has created tools to survey the fatigue data within JRC's database and feed screened data into analyses. In parallel, a testing programme has been specified and is underway. The testing programme is focussed on studying the effect of variable amplitude loading, environment, surface condition, and specimen geometry on the fatigue life of stainless-steel specimens. A materials characterisation work package is investigating the effect of the test conditions on fracture surfaces and combining that analysis with a range of materials properties and test data to contribute towards an improved mechanistic understanding of EAF. An analysis work package is actively working on scientific and engineering models to inform predictions of specimen life and develop approaches to account for the conditions studied in EAF assessments. Finally, the project will deliver guidance on the use of laboratory-scale data for component-scale applications. This paper will outline progress from the first two years of the project. Specific details relating to the testing, materials characterisation, and analysis work packages will be presented in additional papers and presentations during the INCEFA-SCALE session.</p

INCEFA-SCALE (Increasing Safety in NPPs by Covering Gaps in Environmental Fatigue Assessment - Focusing on Gaps Between Laboratory Data and Component-Scale)

INCEFA-SCALE is a five-year project supported by the European Commission HORIZON2020 programme. It is the successor to the INCEFA-PLUS programme that ran from 2015 to 2020. INCEFA-SCALE kicked off in September 2020. The objective is to continue work, advancing the ability to predict lifetimes of Nuclear Plant components when subjected to Environmental Assisted Fatigue loading (EAF). It has been generally observed by nuclear plant operators that there appears to be a disconnect between the perceived difficulty of providing an acceptable assessment result with the current EAF methodologies and the good service experience with regard to this specific degradation mechanism. It is internationally recognised that a possible contributor to this discrepancy is the transferability of laboratory-scale tests to real nuclear components. EPRI, in the USA, is leading a series of component-scale environmental fatigue tests that are expected to advance data availability significantly; however, the ability to address transferability of laboratory-scale tests to real component geometries and loadings will still be constrained by limited test data. This is the knowledge gap addressed by INCEFA-SCALE. The project strategy will be (1) the development of comprehensive mechanistic understanding developed through detailed examination of test specimens and MatDB datamining, and (2) testing focussed on particular aspects of component-scale cyclic loading.INCEFA-PLUS project, and from other external sources such as USNRC, EPRI, MHI and the AdFaM project). In parallel, the test programme needs have been agreed, and protocols agreed for managing data, testing, and material examinations consistently. Testing commenced after one year and will run for three years. Finally, the project will deliver guidance on the use of laboratory-scale data for component-scale applications. This paper will report the first year of the project and detail the preparations completed to ensure the project maximises the achievement of its objectives.</p

Hydrolysis of peptidoglycan is modulated by amidation of meso-diaminopimelic acid and Mg2+ in Bacillus subtilis

The ability of excess Mg2+ to compensate the absence of cell wall related genes in Bacillus subtilis has been known for a long time, but the mechanism has remained obscure. Here, we show that the rigidity of wild-type cells remains unaffected with excess Mg2+, but the proportion of amidated meso-diaminopimelic (mDAP) acid in their peptidoglycan (PG) is significantly reduced. We identify the amidotransferase AsnB as responsible for mDAP amidation and show that the gene encoding it is essential without added Mg2+. Growth without excess Mg2+ causes asnB mutant cells to deform and ultimately lyse. In cell regions with deformations, PG insertion is orderly and indistinguishable from the wild-type. However, PG degradation is unevenly distributed along the sidewalls. Furthermore, asnB mutant cells exhibit increased sensitivity to antibiotics targeting the cell wall. These results suggest that absence of amidated mDAP causes a lethal deregulation of PG hydrolysis that can be inhibited by increased levels of Mg2+. Consistently, we find that Mg2+ inhibits autolysis of wild-type cells. We suggest that Mg2+ helps to maintain the balance between PG synthesis and hydrolysis in cell wall mutants where this balance is perturbed in favor of increased degradation

Fusion reactions of Ni 58,64 + Sn 124

none22siMeasurements of fusion excitation functions of Ni58+Sn124 and Ni64+Sn124 are extended towards lower energy to cross sections of 1 μb and are compared to detailed coupled-channels calculations. The calculations clearly show the importance of including transfer reactions in a coupled-channels treatment for such heavy systems. This result is different from the conclusion made in a previous article which claimed that the influence of transfer on fusion is not important for fusion reactions of Ni+Sn. In the energy region studied in this experiment no indication of fusion hindrance has been observed, which is consistent with a systematic study of this behavior.noneJiang, C.L.; Stefanini, A.M.; Esbensen, H.; Rehm, K.E.; Almaraz-Calderon, S.; Avila, M.L.; Back, B.B.; Bourgin, D.; Corradi, L.; Courtin, S.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Haas, F.; Mazzocco, M.; Montanari, D.; Montagnoli, G.; Mijatovic, T.; Sagaidak, R.; Santiago-Gonzalez, D.; Scarlassara, F.; Strano, E.; Szilner, S.Jiang, C. L.; Stefanini, A. M.; Esbensen, H.; Rehm, K. E.; Almaraz Calderon, S.; Avila, M. L.; Back, B. B.; Bourgin, D.; Corradi, L.; Courtin, S.; Fioretto, E.; Galtarossa, F.; Goasduff, Alain; Haas, F.; Mazzocco, Marco; Montanari, Daniele; Montagnoli, Giovanna; Mijatovic, T.; Sagaidak, R.; Santiago Gonzalez, D.; Scarlassara, Fernando; Strano, Emanuele; Szilner, Suzan