Propuesta para cuantificar la eficacia de requisitos tecnológicos de materiales estructurales destinados al sector nuclear
Propuesta para cuantificar la eficacia de requisitos tecnológicos de materiales estructurales destinados al sector nuclear Durante la concepción de cualquier proyecto industrial que contenga la construcción o fabricación de algún elemento que deba proporcionar una función estructural, es de suma importancia tras la selección de materiales a emplear, realizar una adecuada selección de la normativa que contiene los requisitos tecnológicos que deben cumplir, con el objeto de asegurar que son adecuados para la finalidad inicialmente prevista. La disertación desarrollada en este trabajo corresponde con una problemática de indudable actualidad, ya que recientemente, un informe oficial (FANC, 2012) ha indicado que las fisuras detectadas en la vasija del reactor de la Central Nuclear Belga de Doel III, pudieron deberse a errores cometidos en el proceso de fabricación, y que por tanto esto pudiera haber sido motivado por el empleo de ciertos requisitos tecnológicos de materiales descritos en sus correspondientes especificaciones. Aunque,…
Quantitative analysis of prediction models of hot cracking in industrial stainless steels using standardized requirements
Quantitative analysis of prediction models of hot cracking in industrial stainless steels using standardized requirements In this paper, a systematic analysis of different methods of δ-ferrite estimation is carried out based on the well-known relationship between δ-ferrite content and hot cracking in stainless steels. Additionally, the influence of certain chemical requirements on δ-ferrite stabilization and their relationship to hot cracking is evaluated by the application of a deterministic algorithm based on stringency levels. The results obtained from the application of the stringency level method and prediction diagrams permit the selection of the best option among materials according to their standardized specifications. In addition, the advantage of this integrated method is that we can evaluate particular elemental influences and assign relative weightings to create a database for materials selection… See all…
Prediction of the fatigue behaviour of cladding materials used in the manufacture of reactor pressure vessels
Prediction of the fatigue behaviour of cladding materials used in the manufacture of reactor pressure vessels In this work, an analysis of the fatigue requirements of cladding materials as described by ASME B&PV and KTA codes has been performed using a stringency level methodology. Thus, ASME B&PV curves show a maximum fatigue stress requirements greater than those required by the KTA standards for the same number of cycles; this is from a value of 10 up to 2 x 105 cycles. Applying the stringency level (SL) methodology, we have obtained a SL equal to 5 for ASME fatigue requirements and a SL equal to 4.6 for KTA fatigue requirements… See all…
Polymers Selection for Harsh Environments to Be Processed Using Additive Manufacturing Techniques
Polymers Selection for Harsh Environments to Be Processed Using Additive Manufacturing Techniques In this work, a methodology for selecting a combination of polymers and their associated additive manufacturing (AM) routes is presented. The binomial consisting of materials performance for the intended application and the most suitable AM process and its production strategy is solved by the application of a multicriteria approach along with a stringency level methodology. The case study has been the analysis of physical and radiation tolerance features of thermoplastic nature candidates for the additive manufacture of mechanical, electromechanical and electrical components for harsh environments in a nuclear power plant. The obtained results allow select an additive manufacturing route along with a production strategy based on large batches or small batches. Using a selective laser sintering (SLS) additive manufacturing route, PP+EPDM can be a good option to manufacture mechanical heavily stressed components, whereas PA can be a versatile…
Criterios técnicos de selección de materiales en la fabricación de recipientes especiales destinados a aplicaciones de alta exigencia
Criterios técnicos de selección de materiales en la fabricación de recipientes especiales destinados a aplicaciones de alta exigencia La selección de materiales es una compleja tarea que resulta ser imprescindible en la etapa de diseño de cualquier componente estructural. En relación a esta temática, este artículo presenta una revisión de los aspectos fundamentales involucrados en la selección de materiales para un caso concreto de aplicación de alta exigencia, como es la fabricación de recipientes especiales para el sector nuclear… See all…
Analysis of mechanical and thermal properties of elastomers for manufacturing of components in the nuclear industry
Analysis of mechanical and thermal properties of elastomers for manufacturing of components in the nuclear industry Many subcomponents of nuclear equipment are manufactured using polymers, where it could be highlighted the role of elastomers as sealants. The aim of this work is to analyze several mechanical and thermal properties of BUNA-N, Neoprene and Viton intended to nuclear power applications. Neoprene (polychloroprene) is the better option if the levels of irradiation are the highest postulated and it exhibits the most balanced performance between required properties, showing also the best mechanical behaviour. On the other hand, the analysis of activation energies provided by EPRI 1009748 exhibits that BUNA-N shows the greatest qualified lifetime… See all..
Selection of candidate materials for reactor pressure vessels: Application of irradiation embrittlement prediction models and a stringency level methodology
Selection of candidate materials for reactor pressure vessels: Application of irradiation embrittlement prediction models and a stringency level methodology The selection of materials for the reactor pressure vessel manufacturing is a complex process that involves great responsibility because small differences in chemical composition can adversely affect the manufacturing process and the in-service behavior of the material. Thus, it is recommendable to perform previous materials pre-selection stages based on the state-of-the-art knowledge, integrating research results with standardized requirements and using simplifier materials selection methodologies like the stringency level method. To address this issue, an evaluation of the influence of chemical composition on the shift of the ductile-to-brittle transition temperature has been performed using the most used and consolidated prediction models that are R.G. 1.99 Rev.2, NUREG/CR-6551, and ASTM E 900-02. A proposal of maximum limits for copper, nickel, and phosphorous to avoid irradiation embrittlement has been presented to carry out the…
Evolución con la temperatura de requisitos mecánicos de materiales empleados en la fabricación de equipos a presión para la industria nuclear
Evolución con la temperatura de requisitos mecánicos de materiales empleados en la fabricación de equipos a presión para la industria nuclear This article presents an analysis, with respect to temperature, of the evolution of requirements of mechanical behavior of materials used in the manufacture of special pressure vessels for the nuclear sector. It has been verified that the evolution described by the KTA and ASME B&PV codes for elastic limit requirements is similar to the adjustment obtained experimentally on specimens from surveillance capsules taken from North American nuclear power plants. Likewise, it has been concluded that the materials forged for use in the manufacture of the reactor vessel, whether they are specified by ASME B&PV or in the KTA standards, must have a mechanical resistance superior to that required for materials manufactured by processes of lamination. Also, the forged material specified by ASME B&PV has a higher resistance to thermal…
Quantitative evaluation of mechanical and thermal properties of candidate thermoplastics for additive manufacturing intended to mild environment nuclear applications
Quantitative evaluation of mechanical and thermal properties of candidate thermoplastics for additive manufacturing intended to mild environment nuclear applications Polymer powders for additive manufacturing (AM) must exhibit thermoplastic behavior so that they can be melted and re-melted to permit bonding of one layer to another. In this work, a methodology to select thermoplastics suitable for AM is described. As a case study, 21 thermoplastics intended to mechanical applications in nuclear power plants under mild environment (due to their moderated radiation resistance) are analysed using a stringency level methodology. The selected properties for the study have been the tensile strength (TS), elongation (EL), thermal expansion coefficient (α) and thermal conductivity (k)… See all…
Multicriteria materials selection for extreme operating conditions based on a multiobjective analysis of irradiation embrittlement and hot cracking prediction models
Multicriteria materials selection for extreme operating conditions based on a multiobjective analysis of irradiation embrittlement and hot cracking prediction models A methodology for evaluating different combinations of materials specifications for extreme environment applications is presented. This new approach addresses the materials selection problem using a multicriteria stringency level methodology that defines several thresholds obtained by analyzing different prediction models of irradiation embrittlement and hot cracking. To solve the conflicts among thresholds as provided by the different prediction models, a multiobjective approach is carried out. Materials for reactor pressure vessels have been considered as case study. It has been concluded that the best option to manufacture a pressure vessel for a pressurized water modern reactor is the selection of German manufacturing standards. Finally, a sensitivity analysis of the proposed methodology has been performed to evaluate the divergences between the single stringency level methodology and the new proposal including multicriteria decision making…