Misure spettrometriche gamma di concentrazioni radionuclidiche in campioni ambientali e alimentari in situazioni di emergenza

Safety studies of a hydrogen refuelling station: Determination of the occurrence frequency of the accidental scenarios

At present, the hydrogen vehicles technology appears to have future Prospective for reduction in greenhouse gas emissions. Nevertheless, the development of such a technology requires appropriate infrastructures for production, Storage and refuelling stages in a refuelling station. This one presents safety challenges due to the hydrogen chemicophysical characteristics. So, to avoid hazards, it is necessary to implement safety practices that, if early adopted in the development of a fuelling station project, can allow very low impact, safety being incorporated in the project itself. However, a drawback is the not sufficient experience and the scarcity of the relevant data collection. To deepe…

Analysis of Protected Accidental Transients in the EFIT Reactor With the RELAP5 Thermal-Hydraulic Code

The European Facility for Industrial Transmutation (EFIT) is aimed at demonstrating the feasibility of transmutation process through the Accelerator Driven System (ADS) route on an industrial scale. The conceptual design of this reactor of about 400 MW thermal power is under development in the frame of the European EUROTRANS Integrated Project of the EURATOM Sixth Framework Program (FP6). EFIT is a pool-type reactor cooled by forced circulation of lead in the primary system where the heat is removed by steam generators installed inside the reactor vessel. The reactor power is sustained by a spallation neutron source supplied by a proton beam impinging on a lead target at the core centre. A …

Rewetting of a hot vertical surface by liquid sprays

Hot surfaces rewetting interests several technological fields. A very important application is in nuclear reactors technology, where it governs the cooling of overheated fuel elements during hypothesized loss of coolant accidents (LOCAs). This phenomenon is also important in many normal processes and accidental situations taking place in conventional processes. For example when the integrity of metallic containers, filled by toxic or dangerous substances, is endangered by a hypothetical fire. The rewetting consists in the re-establishment of coolant in contact with metallic surfaces become dried due to high temperature. To this end cold liquid is injected on these surfaces via sprays or other …

Prediction of the heat exchange in MEGAPIE facility by using RELAP5 code

RPN safety analysis to reduce the risk of malpractices in high dose rate brachytherapy

A new fuzzy rule-based assessment model is proposed to evaluate the risk priority number in the Failure Mode, Effects, and Criticality Analysis (FMECA) method to rank component failures and human errors from the medical staff, leading to potential radiological over-exposure of patients during high-dose-rate brachytherapy treatment. The obtained results are relevant for a range of causes that have a reasonable probability of producing significant adverse outcomes. Thus, recommendations are provided for procedures and safety devices to reduce the occurrence of radiological over-exposure accidents. This method can solve the problems in conventional FMECA applications and improve the safety and…

Preliminary T/H and Transient Analyses for EFIT Reactor design

Thermal-hydraulic analysis on the cooling system of the target in the SPES plant

RELAP5 Modification for CHEOPE Simulations

Investigation of RELAP Capability to Simulate the LBE Cooling System Thermal-Hydraulic

The paper subject regards the validation of the RELAP5/Mod3.2.2B, the best estimate code modified to deal with fluids of interest for the XADS (eXperimental Accelerator Driven System), a Lead Bismuth Eutettic alloy (LBE) cooled ADS design set up at Ansaldo Industry. The validation will be made exploiting the experimental program carried out on support of XADS design and MEGAPIE experiment, at the ENEA Research Centre of Brasimone (Italy), making use of CHEOPE and CIRCE facilities. The comparison between experimental results and post test calculations allows the check ofthe code capability in simulating the 1Dym fluid-dynamic of heavy metals. In particular, CHEOPE tests have provided data fa…

Studio della sicurezza di una stazione di rifornimento di idrogeno per autotrazione mediante l’uso integrato di tecniche di analisi di rischio

TREEZZY2, a Fuzzy Logic Computer Code for Fault Tree and Event Tree Analyses

In conventional approach to reliability analysis using logical trees methodologies, uncertainties in system components or basic events failure probabilities are approached by assuming probability distribution functions. However, data are often insufficient for statistical estimation, and therefore it is required to resort to approximate estimations. Moreover, complicate calculations are needed to propagate uncertainties up to the final results. In our work, in order to take account of the uncertainties in system failure probabilities, the methodology based on fuzzy sets theory is used both in fault tree and event tree analyses. This paper just presents our work in this issue, which resulted…

Thermalhydraulic analyses of overpower transients in the EFIT reactor

FMECA Analyses of radiological over-exposure accident to patients in brachytherapy

This paper presents safety analyses of accidental events which can involve patient during High Dose Rate brachytherapy treatment in over-exposures. The study has been performed by using the well-known techniques FMECA modified by Fuzzy logic theory. Moreover, fuzzy HEART methodology was employed in order to evaluate human error probabilities for each treatment stage. The obtained results, aimed to obtain a list of the deviations with a reasonable probability to produce significant adverse outcomes, provided some recommendations for procedures and safety equipments to reduce the occurrence of radiological over-exposure accidents.

Decay Heat Removal and Transient Analysis in Accidental Conditions in the EFIT Reactor

The development of a conceptual design of an industrial-scale transmutation facility (EFIT) of several 100 MW thermal power based on accelerator-driven system (ADS) is addressed in the frame of the European EUROTRANS Integral Project. In normal operation, the core power of EFIT reactor is removed through steam generators by four secondary loops fed by water. A safety-related decay heat removal (DHR) system provided with four independent inherently safe loops is installed in the primary vessel to remove the decay heat by natural convection circulation under accidental conditions which are caused by a loss-of-heat sink (LOHS). In order to confirm the adequacy of the adopted solution for decay…

Analisi di sicurezza mediante l’uso di tecniche ad alberi di guasto FUZZY dell’impianto nucleare dimostrativo XADS

Education and Research in Nuclear Engineering and Radiological Protection at Nuclear Engineering Department of Palermo University

Thermal hydraulic analyses in the windowless target of an Accelerator Driven System

SAFETY ANALYSES OF POTENTIAL EXPOSURE IN MEDICAL IRRADIATION PLANTS BY FUZZY FAULT TREE

A Training Experience of Operators with the AGN-201 “Costanza” Research Reactor of Palermo University

The nuclear reactor AGN-201 named “Costanza”, installed at the Nuclear Engineering Section of the Department of Energy of the University of Palermo, is a “zero power” research reactor designed to be mainly used for education purposes as well as for research applications, such as activation analysis and irradiation tests, and last, but not the least, for radionuclide production to be used in nuclear medical applications. Due to its intrinsic safety and low margin of reactivity (less than 350 p.c.m.) so as to the absence of start-up and shut-down time limits, it represents a useful training tool for operators, too. This paper reports some of the activities carried out within the framework of …

Analisi di sicurezza nella procedura di protonterapia oculare applicata presso i Laboratori del Sud dell’INFN di Catania

A partire dal 2002, l’Azienda Ospedaliera Universitaria “Policlinico Vittorio Emanuele” di Catania ha effettuato il trattamento di circa 350 pazienti affetti da neoplasie oculari mediante fasci di protoni prodotti con il ciclotrone disponibile presso i Laboratori nazionali del Sud (LNS). Tale impianto viene utilizzato per attività di ricerca nell’ambito della fisica sperimentale, per cui è stato necessario modificare le caratteristiche del fascio, rendendolo idoneo alle applicazioni cliniche. Il lavoro di ricerca ha riguardato lo svolgimento della analisi del rischio volto ad individuare possibili fallimenti nelle procedure adottate per il trattamento del paziente sottoposto a cicli di prot…

Dry deposition models for radionuclides dispersed in air: a new approach for deposition velocity evaluation schema

In the framework of a National Research Program funded by the Italian Minister of Economic Development, the Department of Energy, Information Engineering and Mathematical Models (DEIM) of Palermo University and ENEA Research Centre of Bologna, Italy is performing several research activities to study physical models and mathematical approaches aimed at investigating dry deposition mechanisms of radioactive pollutants. On the basis of such studies, a new approach to evaluate the dry deposition velocity for particles is proposed. Comparisons with literature experimental data show that the proposed dry deposition scheme allows to capture the main phenomena involved in the dry deposition process…

Multiple failure accidental transients in the LBE-XADS

New Implementations in RELAP5 for Post-Test Analysis of the MEGAPIE Irradiation Phase

Fuzzy modelling of HEART methodology: application in safety analyses of accidental exposure in irradiation plants

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 irradiation industrial plants. For these analyses the HEART methodology, a first generation of the Human Reliability Analysis method, has been employed to evaluate the probability of human erroneous actions. This technique has been modified by us on the basis of fuzzy set concept to more directly take into account the uncertainties of the so called error-promoting factors, on which the method is grounded. The results allow also to provide some recommendations on procedures and safety equipments to reduce the radiological expo…

Modifying RELAP5 code to deal with helical coiled ducts

Rewetting by liquid spray of a hot metallic wall

Recent improvement of RELAP5 as numerical tool for interpretation of thermal-hydraulic experiments

Safety analysis in the LBE-Cooled XADS plant through an integrated use of HAZOP, FAULT TREE and thermalhydraulic transient analyses

A detailed description of possible accidental scenarios, with their frequency of occurrence and their consequences, taking into account both internal and external causes that might contribute to them, can be attained by using the most important risk analysis methodologies (HAZard and OPerability studies, HAZOP; Event Tree, ET; Fault Tree, FT; etc.). As it is known, the Fault Tree methodology is aimed at the evaluation of the frequency of an undesired accidental event (Top Event, TE), and is used to describe this one as a combination of primary events identified, for example, by a HAZOP analysis [1]. However, the classic HAZOP analysis, while allowing to perform an exhaustive study of the ex…

Dividing two-phase flow in branching conduits with large diameter horizontal main pipes and lateral branches

Thermalhydraulic analyses of overpower transients without proton beam trip in the XADS facility

Analisi di sicurezza di una stazione di rifornimento di idrogeno per autotrazione:uso delle tecniche FMEA e HAZOP

Piani di Sicurezza per il trasferimento di sorgenti di radiazioni gamma e neutroni ad alta attività

La movimentazione di sorgenti ad alta attività, sia che si tratti dell’acquisizione, trasporto e collocazione di nuove sorgenti in impianti di irraggiamento, o del trasferimento di sorgenti all’interno della stessa struttura, deve essere pianificata nei minimi dettagli con un piano di lavoro. Ciò è fondamentale per l’analisi di tipo radioprotezionistico ma anche dal punto di vista della valutazione dei rischi di altra natura, non ultima la movimentazione dei carichi. Tale analisi preventiva viene effettuata avvalendosi sinergicamente di un gruppo di esperti con diverse competenze e varie figure di responsabilità (Responsabile delle sorgenti, RSPP, Esperto Qualificato, Medico Autorizzato, …)…

RELAP5 simulations for CIRCE experiments

TREEZZY2, a Fuzzy Logic Computer Code for Fault Tree and Event Tree Analyses

In conventional approach to reliability analysis using logical trees methodologies, uncertainties in system components or basic events failure probabilities are approached by assuming probability distribution functions. However, data are often insufficient for statistical estimation, and therefore it is required to resort to approximate estimations. Moreover, complicate calculations are needed to propagate uncertainties up to the final results. In our work, in order to take account of the uncertainties in system failure probabilities, the methodology based on fuzzy sets theory is used both in fault tree and event tree analyses. This paper just presents our work in this issue, which resulted…

Risk analysis of the storage unit in a hydrogen refuelling station