Guglielmo Lomonaco

University of Genoa | UNIGE · Dipartimento di Ingegneria Meccanica, Energetica, Gestionale e dei Trasporti (DIME)

Fusion-fission hybrid reactors are concepts of subcritical reactors based on the coupling of fusion and fission devices. In this case, the fusion reactor would work as an external neutron supplier for the fission core of the machine. Such systems could, in principle, operate as multipurpose machines, such as energy generators, breeders and waste bu...

The studies on the development of fusion-fission hybrid reactors (FFHR) have gained consensus in recent years as an intermediate step before fusion energy. This work proposes a possible approach to FFHRs based on the coupling of a Reversed Field Pinch fusion machine and a Molten Salt Subcritical fission test bed. The proposed test bed is characteri...

New nuclear technologies are currently being study to face High Level Waste treatment and disposal issues. Generally, GEN-IV fission Fast Reactors (FR) are considered the waste-burners of the future. In fact, a fast flux turns out to be the best choice for actinides irradiation in critical reactors because of favorable cross section conditions. Dif...

https://youtu.be/uvcRy8cW2_E?si=3sj1XTAran1YRDLn

To ensure the applicability of accident-tolerant fuels, their behaviors under various accidental conditions must be assessed. While the dependences of the behavior of single physical parameters can be investigated in single-or separate-effect experiments, and more complex phenomena can be investigated using integral-effect tests, the behavior of an...

From the late 1950s to date, nuclear thermal propulsion has the purpose of making possible missions impossible to accomplish with chemical propulsion. The use of hydrogen as a propellant and a fuel resistant to very high temperatures guarantees exceptional propulsive performance. Since the NERVA project, a propulsion system with such capabilities h...

FFHR, RFP FFHR, reversed field pinch, RFP, Fusion-Fission Hybrid Reactor

The aim of this work is to present a new analytical model to evaluate jointly the mechanical integrity and the fitness-for-service of nuclear reactor pressure-vessels steels. This new methodology integrates a robust and regulated irradiation embrittlement prediction model such as the ASTM E-900 with the ASME Fitness-for-Service code used widely in...

Nuove tecnologie, sviluppate anche grazie a UniGe, possono rendere il nucleare un alleato della transizione energetica.

The cataloguing and revision of reactor pressure vessels (RPV) manufacturing and in-service inspection codes and their standardized material specifications-as a technical heritage-are essential for understanding the historical evolution of criteria and for enabling the comparison of the various national regulations, integrating the most relevant re...

Fusion-fission hybrid systems (FFH) represent a coupling between a fusion device and a subcritical fission reactor driven by neutrons produced by fusion reactions. This kind of systems, in principle, can be useful for different purposes, for example, as energy amplifier or as nuclear waste burner. In this work, the preliminary characteristics and p...

Studies are in progress in order to revisit the status and the potentiality of the Reversed Field Pinch (RFP) as a fusion core in FFHR, taking into account: (i) the recent progress in RFP physics brought by the results of RFX-mod (R = 2, a = 0.46, Ip = 2MA), mainly about MHD modes control, (ii) the expected performance improvements resulting from t...

Hydrogen production is a topical issue in an energy scenario where decarbonization is a priority, especially with reference to the transport sector that has a great weight on global emissions. Starting from this consideration, GIF (Generation-IV International Forum) investigated the possibility to produce hydrogen by nuclear energy. The "classic" s...

The topic of Nuclear Safety Culture touches several different aspects with contributions from the main organizations involved in nuclear projects and belonging to vendors, utility and regulators. Two nuclear safety directives issued by the European Commission emphasize the fundamental principle of national responsibility for nuclear safety and are...

The unique design features of the molten salt fast reactor (MSFR) should enable higher coolant temperatures than in conventional water reactors, with a significant improvement in the achievable thermodynamic performance. The use of a molten salt as both fuel and coolant, however, poses several advanced heat transfer challenges, such as the design o...

uclear engineering requires computationally efficient methods to simulate different components and systems of plants. The Lattice Boltzmann Method (LBM), a numerical method with a mesoscopic approach to Computational Fluid Dynamic (CFD) derived from the Boltzmann equation and the Maxwell–Boltzmann distribution, can be an adequate option. The purpos...

Fuel burnup analysis requires a high computational cost for full core calculations, due to the amount of the information processed for the total reaction rates in many burnup regions. Indeed, they reach the order of millions or more by a subdivision into radial and axial regions in a pin-by-pin description. In addition, if multi-physics approaches...

In the framework of MYRRHA Project, a pool-type experimental and material testing irradiation facility operated with Lead Bismuth Eutectic (LBE) coolant and able to operate in both sub-critical and critical mode is designed to be built in Mol, Belgium, in SCK•CEN domain. SCK•CEN entered the pre-licensing phase for the MYRRHA reactor. A complete saf...

We studied a flexible ADS-based irradiation facility with fast neutrons inside the core and slow neutrons in the composite reflector containing light materials. The fast reactor core has been designed using MCNP-6 code with a mixed reflector formed by three concentric cylindrical layers (lead+graphite+lead) in order to have different neutrons spect...

Zirconium based alloys are commonly used as material for fuel claddings in the light water reactors. Claddings act as first metallic barriers against loss of fission products during the nuclear power plant operation, intermittent storage or final dry storage. The integrity of claddings is always critical issue during reactor operation and during st...

Accelerator Driven Systems (ADS) seem to be a good solution for safe nuclear waste transmutation. One of the most important challenges for this kind of machine is the target design, particularly for what concerning the target cooling system. In order to optimize this component a CFD-based approach has been chosen. After the definition of a referenc...

The design of compact heat exchangers and their mass flow distributors is still based on empirical approaches and both numerical analyses and experimentations are needed for designing the best geometries useful to reduce the mass flow rate non uniformities in parallel channels. As known, this is indeed a cause of reduction in both thermal and fluid...

Aim of this work is the preliminary thermal-fluid-dynamic assessment of a subcritical system to perform integral measurements on transmutation processes, designed in the frame of EU CHANDA project: in particular, a low power Accelerator Driven System (ADS) may represent an attractive intermediate step to fill the gap between existing and future fac...

This paper aims to compare three Monte Carlo (MC) burnup based codes, i.e. MCNP6, Monteburns and Serpent on a future prototype reactor, named ALLEGRO, based on Gas cooled Fast Reactor (GFR) technology. GFR reactors are one of the proposed Generation-IV fast reactors; ALLEGRO facility is scheduled to be built in Europe as a GFR demonstrator, so its...

In this work, we report studies on a fast low power accelerator driven system model as a possible experimental facility, focusing on its capabilities in terms of measurement of relevant integral nuclear quantities. In particular, we performed Monte Carlo simulations of minor actinides and fission products irradiation and estimated the fission rate...

Although Lead-cooled Fast Reactor (LFR) is not a new concept, it continues to be an example of innovation in the nuclear field. Recently, there has been strong interest in liquid lead (Pb) or liquid lead-bismuth eutectic (LBE) both critical and subcritical systems in a relevant number of Countries, including studies performed in the frame of GENERA...

The present paper reports a numerical investigation of a forced convection water flow within a two-dimensional ribbed channel. A uniform heat flux is applied on the external walls. The flow regime is turbulent and Reynolds numbers are in the range 10·10^3÷100·10^3. Square and chamfered rib shapes with different arrangements are analyzed in terms of...

The fusion-fission hybrid reactor is a promising technology that is likely to assume more and more importance in the global energy scenario in the coming years. Although this kind of nuclear system dates back to the earliest times of the fusion projects (when it was recognized that using fusion neutrons to “support” nuclear fission fuel cycle could...

The neutron multiplication factor k-eff is a key quantity to characterize subcritical neutron multiplying devices and for understanting their physical behaviour, being related to the fundamental eigenvalue of Boltzmann transport equation. Both the maximum available power - and all quantities related to it, like, e.g. the effectiveness in burning nu...

In this work we report initial studies on a low power Accelerator-Driven System as a possible experimental facility for the measurement of relevant integral nuclear quantities. In particular, we performed Monte Carlo simulations of minor actinides and fission products irradiation and estimated the fission rate within fission chambers in the reactor...

Heavy Liquid Metals (HLM) are objects of interest in the nuclear research sector because of their optimal thermal and neutronic properties; the development and the validation of models allowing to predict their behaviour are fundamental for the future development of the Generation IV energy systems. An experimental facility named SESAME-stand, is p...

In the context of GEN-IV heavy liquid metal-cooled reactors safety studies, the flow blockage in a fuel sub-assembly is considered one of the main issues to be addressed and one of the most important accidents for Lead Fast Reactors (LFR). In order to model the temperature and velocity field inside a wrapped fuel assembly under unblocked and blocke...

In the framework of MYRRHA Project, a pool-type experimental and material testing irradiation facility operated with Lead Bismuth Eutectic (LBE) coolant and able to operate in both sub-critical and critical mode is designed to be built in Mol, Belgium, in SCK•CEN domain. In addition to the material testing function, targets of the MYRRHA reactor ar...

Aim of this work is the preliminary thermal-fluid-dynamic assessment of a subcritical system to perform integral measurements on transmutation processes, designed in the frame of EU CHANDA project: in particular, a low power Accelerator Driven System (ADS) may represent an attractive intermediate step to fill the gap between existing and future fac...

The design of compact heat exchangers and their mass flow distributors is still based on empirical approaches and both experimentations and numerical analyses are needed for defining the best geometries able to reduce the mass flow rate non uniformities in parallel channels. This is a cause of reduction in both thermal and fluid-dynamic performance...

The use of passive safety systems are more and more diffused in many technological fields. Natural circulation is probably one of the main phenomenon applied in this kind of systems: indeed, as known, by means of gravity and buoyancy forces, the fluids can circulate without any external power sources. In this paper, a preliminary analysis (also by...

The CFD analysis of a Venturi nozzle operating in LBE (key component of the CIRCE facility, owned by ENEA) is presented in this paper. CIRCE is a facility developed to investigate in detail the fluid-dynamic behavior of ADS and/or LFR reactor plants. The initial CFD simulations have been developed hand in hand with the comparison with experimental...

The neutron multiplication factor k e f f is a key quantity to characterize subcritical neutron multiplying devices and for understanting their physical behaviour, being related to the fundamental eigenvalue of Boltzmann transport equation. Both the maximum available power-and all quantities related to it, like, e.g. the effectiveness in burning nu...

We report on the studies of an irradiation facility based on an accelerator-driven subcritical nuclear research reactor, which can simultaneously provide a fast flux in the core and a thermal flux in the reflector, that we will call a hybrid fast-slow ADS. The conceptual design presented here, inspired by [1], starts from a 432 kW (keff=0.967) ADS...

The MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) project, started at SCK·CEN since 1999, aims at the construction of a pool-type sub-critical Accelerator-Driven System (ADS) which could also operate as a critical reactor. The primary system, enclosed in the primary vessel, is filled with Lead Bismuth Eutectic (LBE) whic...

This paper shows some results obtained through simulating a VVER-1000 mock-up installed within the LR-0 research reactor in the Research Centre Řež (Czech Republic): the simulations have been performed by using the Serpent 2 and MCNP6 Monte Carlo codes. The mock-up is analysed in 6 different critical configurations, obtained with variation of coola...

The fusion-fission hybrid reactor is a promising technology that is likely to assume an increasingly important role in the global energy scene in the coming years. This kind of reactor can use both the nuclear fusion and fission processes to produce energy: neutrons from fusion reactions are used to sustain the fission of a sub-critical system. Thi...

Lead-cooled fast reactor (LFR) has both a long history and a penchant of innovation. With early work related to its use for submarine propulsion dating to the 1950s, Russian scientists pioneered the development of reactors cooled by heavy liquid metals (HLM). More recently, there has been substantial interest in both critical and subcritical reacto...

Nuclear safety, nuclear security and nuclear safeguards regimes have not historically developed at the same pace and surely have not reached the same level of maturity. Nevertheless, these aspects are of special relevance in the current global nuclear energy context when considering the numerous countries that have and will have the legitimate ambi...

In this presentation, a theoretical and computational analysis is presented of a multi-blade screw pump evolving liquid Lead as primary pump for the reference conceptual design of the Advanced Lead Fast Reactor European Demonstrator (ALFRED). The pump is analyzed at design operating conditions from the theoretical point of view to determine the op...

This paper reports the results of a comparison among JEFF and ENDF/B datasets when used by SERPENT and MONTEBURNS codes on a GFR-like configuration. Particularly, it shows a comparison between the two Monte Carlo based codes, each one adopting three different cross sections dataset, namely JEFF-3.1, JEFF-3.1.2 and ENDF/BVII.1. Calculations have bee...

The interpretation of kinetic experiments for source-driven systems is often based on the relationship between the prompt time response and the multiplicativity of the system. The presence of a reflector may modify the physical features of such response. For systems in which the neutron histories are dominated by the presence of the reflector, it b...

Global water shortage is one of the rising problems that, nowadays and worldwide, Countries and governments have to face. People from many countries have to deal with scarcity of water supply and aquifer pollution that could jeopardize their health and agriculture. Desalination process could be one of the most promising method to hinder such phenom...

This review article is an overview on some recent developments of Generation IV (GEN-IV) gas cooled nuclear reactor performing in the frame of innovative symbiotic fuel cycle mainly by our research group. In fact such reactors, in addition to energy generation, can also improve nuclear fuel exploitation and decrease nuclear waste radiotoxicity main...

Within European Partitioning & Transmutation research programs, infrastructures specifically dedicated to the study of fundamental reactor physics and engineering parameters of future fast-neutron-based reactors are very important, being some of these features not available in present zero-power prototypes. This presentation will illustrate the con...

Among the strategies which carry on the main aim of minimizing MA (Minor Actinides) inventories, transmutation is one of the most. In fact, FR (Fast Reactors), in addition to energy generation, can also decrease nuclear waste radiotoxicity mainly by transmutation processes. The implementation of this strategy might be helped by some typical feature...

Heavy-liquid metals, such as lead and lead–bismuth eutectic, are promising candidates as coolant for advanced GEN-IV fast reactors as well as for Accelerator-Driven Systems. The advancing knowledge of the thermal-hydraulic behavior of these fluids leads to explore new geometries and new concepts aimed at optimizing the key components of a GEN-IV re...

A technologically feasible transition towards a realistic and sustainable hydrogen economy (i.e. on large scale and without carbon dioxide emissions) could be made through the use of nuclear energy. In fact, nowadays hydrogen production methods without the employment of fossil fuel represent only a low share of the total production; but the use on...

Since the ’90s interest has grown in the characterization of sub-critical systems. Because they should not have control/shutdown devices, it is necessary to prevent by design neutron flux divergence in all conditions. Most of the available theoretical models on neutron kinetic behavior in multiplying systems are tailored on the description of criti...

This paper reports the results of a comparison among JEFF and ENDF/B datasets when used by SERPENT and MONTEBURNS codes on a GFR-like configuration. Particularly, it shows a comparison between the two Monte Carlo based codes, each one adopting three different cross sections dataset, namely JEFF-3.1, JEFF-3.1.2 and ENDF/BVII.1. Calculations have bee...

The currently dominant open fuel cycles have resulted in the gradual accumulation of (relatively) large quantities of highly radioactive or fertile materials in the form of depleted uranium, plutonium, minor actinides (MA) and long-lived fission products (LLFP). For low-activity wastes a heavily shielded surface repository is required. Spent fuel c...

Within European Partitioning & Transmutation research programs, infrastructures specifically dedicated to the study of fundamental reactor physics and engineering parameters of future fast-neutron-based reactors are very important, being some of these features not available in present zero-power prototypes. This presentation will illustrate the con...

Transmutation is one of the most promising strategies to minimize Minor Actinides inventories. Particularly, during NPPs operation, Am and Cm isotopes are generated by capture and transmutation processes from U and Pu. High neutron flux (typical of fast reactors) and high neutron capture cross-section can help to implement such strategy. Fast React...

This chapter looks at Generation IV nuclear reactors, such as the very high-temperature reactor (VHTR), the supercritical water reactor (SCWR), the molten salt reactor (MSR), the sodium-cooled fast reactor (SFR), the lead-cooled fast reactor (LFR) and the gas-cooled fast reactor (GFR). Reactor designs and fuel cycles are also described.

The corrosion issues in HTR are probably less critical compared to the analogues in other nuclear reactors. Nevertheless it is important to take them into account adequately. In this chapter we consider the following items: a) Structural metallic material corrosion in high temperature conditions b) Graphite corrosion (mainly oxidation) behaviour in...

Aim of the present work: get an overview about the challenges, implications, boundary conditions, assumptions and correlated consequences of different scenarios suggested or envisaged for the deployment of nuclear energy on a global or regional basis.

The double-heterogeneity characterising pebble-bed high temperature reactors (HTRs) makes Monte Carlo based calculation tools the most suitable for detailed core analyses. These codes can be successfully used to predict the isotopic evolution during irradiation of the fuel of this kind of cores. At the moment, there are many computational systems b...