Search results for " impianti nucleari"

Turbulent Fluid Flow in Closed- and Free-Surface Unbaffled Tanks Stirred by Radial Impellers

1996

Thermo-mechanical analysis of irradiation swelling and design optimization of the IFMIF target assembly with bayonet backplate

2017

Abstract The availability of a high flux neutron source for testing candidate materials under irradiation conditions, which will be typically encountered in future fusion power reactors (ITER, DEMO, FPR), is a fundamental step towards the development of fusion energy. To this purpose, the International Fusion Materials Irradiation Facility (IFMIF) represents the reference option to provide the fusion community with a DEMO-relevant neutron source capable of irradiating samples at a damage rate of up to 20 dpa/fpy (in steel) in a volume of 0.5 l. In the framework of the engineering design activities of IFMIF, ENEA is committed in the design of the lithium target assembly (TA) with removable (…

Qualità dell’aria: il Fuzzy Environmental Analogy Index Model (FEAIM) per valutare l’idoneità delle stazioni ai fini modellistici

2020

Tutte le attività volte a studiare le cause primarie e gli effetti dell’inquinamento atmosferico richiedono l’impiego di una rete di monitoraggio della qualità dell’aria ottimizzata per la valutazione dell’esposizione dei bersagli recettori agli effetti degli inquinanti aerodispersi. Nell’ambito di una collaborazione tra ARPA Sicilia e il Dipartimento di Ingegneria dell’Università di Palermo, sono state condotte ricerche per sviluppare una metodologia innovativa utile per ottimizzare l’assetto delle reti di monitoraggio della qualità dell’aria su scala regionale. L’approccio metodologico si fonda su un nuovo indice, chiamato indice di analogia ambientale del territorio (FEAI), basato sulla …

Fuzzy fault tree analysis in modern γ-ray industrial irradiator: Use of fuzzy version of HEART and CREAM techniques for human error evaluation

2008

As well known, the lack of accurate quantitative human reliability data is a serious limitation and source of uncertainty in risk assessment. Therefore, in the last years, many Authors suggested that the use of the fuzzy sets theory can fill up this gap, performing as useful tool when dealing with qualitative or vague information. In such a framework, the present paper refers to the obtained results by using Fuzzy Fault Tree analyses of accidental scenarios which entail the potential exposure of operators working in γ-ray irradiation industrial plant. For these analyses the HEART methodology, a first generation HRA (Human Reliability Analysis) method, has been employed to evaluate the proba…

Bartlett formalism generating functions and Z-transforms in fluctuation and noise theory

1983

Abstract “La theorie des fonctions generatrices s'adapte elle meme et avec la plus grande generalite aux questions des probabilite les plus difficiles.” (Laplace, 1812) “An important part of probability theory consists of the derivation of the probability distribution of the sum of n random variables, each of which obeys a given probability law, and the development of asymptotic forms of these distributions valid for increasing n. Probability generating functions owe their dominant position to the simplification they permit to both problems. Their employment to obtain the successive moments of a probability distribution and to solve the difference equations of probability theory is ancillar…

Statistical physics: Some basic principles of fluctuation and noise theory

1983

Abstract Models have traditionally played a significant role in statistical mechanics. In view of the complexity of the system which statistical mechanics attempt to describe, this is not at all surprising. The study of simplified models has frequently revealed the underlying mathematical structure of many physical questions and in so doing the study of models has contributed directly to a clarification of several paradoxes which beset statistical mechanics. In this paper some of the models which appear to be useful for the discussion of non-equilibrium phenomena are examined in some detail. As usual these models are extremely simplified versions of the actual situations. It is, finally, as…

A Monte Carlo study on the possible lay-out influence in the HCLL-TBM nuclear response

2008

A constitutive model for the thermo-mechanical behaviour of fusion-relevant pebble beds and its application to the simulation of HELICA mock-up exper…

2007

Abstract Within the framework of the R&D activities promoted by EFDA on the Helium-Cooled Pebble Bed Test Blanket Module to be irradiated in ITER, attention has been focused on the modelling of the thermo-mechanical behaviour of both beryllium and lithiated ceramic pebble beds that are envisaged to be used respectively as neutron multiplier and tritium breeder. This behaviour depends, mainly, on the reactor-relevant conditions, the pebble sizes and the breeder cell geometries and a general constitutive model has not yet been validated, especially for fusion-relevant applications. ENEA-Brasimone and the Department of Nuclear Engineering (DIN) of the University of Palermo have performed inten…

Risk assessment of component failure modes and human errors using a new FMECA approach: application in the safety analysis of HDR brachytherapy

2014

Failure mode, effects and criticality analysis (FMECA) is a safety technique extensively used in many different industrial fields to identify and prevent potential failures. In the application of traditional FMECA, the risk priority number (RPN) is determined to rank the failure modes; however, the method has been criticised for having several weaknesses. Moreover, it is unable to adequately deal with human errors or negligence. In this paper, a new versatile fuzzy rule-based assessment model is proposed to evaluate the RPN index to rank both component failure and human error. The proposed methodology is applied to potential radiological over-exposure of patients during high-dose-rate brach…

Safety study of an LNG regasification plant using an FMECA and HAZOP integrated methodology

2015

Abstract A safety analysis was performed to determine possible accidental events in the storage system used in the liquefied natural gas regasification plant using the integrated application of failure modes, effects and criticality analysis (FMECA) and hazard and operability analysis (HAZOP) methodologies. The goal of the FMECA technique is the estimation of component failure modes and their major effects, whereas HAZOP is a structured and systematic technique that provides an identification of the hazards and the operability problems using logical sequences of cause-deviation-consequence of process parameters. The proposed FMECA and HAZOP integrated analysis (FHIA) has been designed as a …