M. Ciotti - Academia.edu (original) (raw)

Papers by M. Ciotti

Progress in Nuclear Energy

Thermal oils are nowadays widely used as heat transfer fluids or cooling media in industrial and ... more Thermal oils are nowadays widely used as heat transfer fluids or cooling media in industrial and energy production plants. Currently, very few data are available about their thermal stability in function of the operating temperatures, which is a crucial parameter to estimate oil structural changes and their possible effects the maximum fluids lifetime. The present work is concerned with ageing tests on a commercially used thermal oil at temperatures higher than the nominal working ones, including a full post-test characterization. At this aim, a dedicated experimental setup was designed and constructed to study the degradation kinetics, and to qualitatively and quantitatively analyze the released gases. As a result, the kinetic parameters were estimated, along with the related changes in the oil thermos-physical properties.

Problems of Atomic Science and Technology, Ser. Thermonuclear Fusion

The full development of a multi-disks uranium target is described, including neutron production a... more The full development of a multi-disks uranium target is described, including neutron production analysis, power deposition distributions, thermo-mechanical simulations and cooling schemes. A detailed material choice and a geometrical optimization were carried on in order to maximize the neutron production. (authors)

17th IEEE/NPSS Symposium Fusion Engineering (Cat. No.97CH36131), 1998

The paper presents a general overview of the Frascati Tokamak Upgrade (FTU) machine operation in ... more The paper presents a general overview of the Frascati Tokamak Upgrade (FTU) machine operation in the last two years. About 3500 pulses were performed (mostly in D2) with a toroidal field between 2.5 and 8 Tesla and a plasma current between 0.35-1.3 MA, according to the experimental programmes. An availability analysis of the FTU plant was performed, which pointed out

AIP Conference Proceedings, 2012

The so called Hybrid (Fusion-Fission) Reactors seem to be a realistic alternative to the drawback... more The so called Hybrid (Fusion-Fission) Reactors seem to be a realistic alternative to the drawbacks of both a pure Fusion and/or a pure Fission reactor; this alternative could also guarantee a "substantial" destruction of the transuranic nuclear waste or production of nuclear combustible. So far, several different hypothesis have been proposed for this type of reactor, all of them based on very advanced and hypothetic fusion scenarios. In the present paper we propose two possible compact (R = 2.5-2.9 m; a = 0.73-0.8 m) high toroidal field (BT = 8.5-7.0 T; Ip = 8-6.8 MA) Tokamaks (based or not on superconductors) to perform a robust and "economic" experiment, propaedeutic to the definitive design of the reactor, where the problems connected with the integration of a Tokamak device with a Fission device can be tested on a realistic base. On both solutions the total fusion power will be of the order of 100 MW and the14 MeV neutron density power of the order of 0.5-1 MW/m2.

Volume 3: Next Generation Reactors and Advanced Reactors; Nuclear Safety and Security, 2014

ABSTRACT The electricity production systems, especially those based on nuclear fission, are incre... more ABSTRACT The electricity production systems, especially those based on nuclear fission, are increasingly facing more tight constraints and are subjected to more deep analyses based on the three aspects of economical sustainability, environmental sustainability and social sustainability. Nuclear Reactors future development has been outlined in the framework of the GIF (Generation IV International Forum), where the Lead Fast Reactor (LFR) is placed among the most promising innovative solutions. Many aspects of LFR offer a huge improvement from different points of view. The non pressurization of the system and the absence of sources of hazardous chemical potential energy enhances consistently its safety aspects, improving the perception of inherent safety of the Generation IV (G4) reactors in the public opinion. At the moment, due to the abundance of the new fossil resources, the competitiveness of Nuclear Power Plants is severely challenged, this aspect representing the most difficult to manage, besides the public acceptability. Moreover, for G4 reactors, an additional “cost premium” associated with the innovative technological concept has to be taken into account. Conversely, looking at the mid-term future, the real economical comparison has to be performed considering as competing sources, according to the IPCC recommendations and constraints enacted by the European Community, only CO2 free sources. In this context, economical competitiveness could be regained depending on the “cost premium” to be added to fossil fuels to become CO2 free, through the improvement of the carbon separation and storage techniques. The intrinsic lead properties (e.g.: low absorption cross section) permit to easily design LFR flexible cores, optimized with respect to a number of possible goals, as a long-lived core with minimal reactivity swing intended for battery concepts, or what is called an “adiabatic” core. where the entire Pu and MA inventory in the spent fuel can be indefinitely reused in a closed fuel cycle. The latter option allows to limit the waste throughput to the fission products only (along with the – unavoidable – losses from fuel reprocessing), and to benefit of natural resources minimization. These are both specific Generation IV goals envisioned to reach nuclear energy sustainability. An overall fuel cycle balance in a scenario with a step by step introduction of LFR reactors fleet grown in a specific geographical area, is in details analyzed in [1] and presented in this conference.

Italy is a country where a long tradition of studies both in the fission and fusion field is cons... more Italy is a country where a long tradition of studies both in the fission and fusion field is consolidated; nevertheless a strong public opinion concerned with the destination of the Spent Nuclear Fuel hinders the development of nuclear power. The possibility to a severe reduction of the NSF mass generated from a fleet of nuclear reactors employing an hypothetical fusionfission hybrid reactor has been investigated in the Italian framework. The possibility to produce nuclear fuel for the fission nuclear reactors with the hybrid reactor was analyzed too.

Smart Materials and Structures, 2007

Fiber optics with a photo-imprinted Bragg grating have been studied for potential use as temperat... more Fiber optics with a photo-imprinted Bragg grating have been studied for potential use as temperature sensors in cryogenic applications. Sensors were coupled with different metallic materials to improve the measurement sensitivity in the very low temperature region, i.e. 4.2-30 K. Various coatings were deposited on the external fiber surface, and full characterization of the tested sensors is given in the paper.

Plasma Physics and Controlled Fusion, 1997

Physica C: Superconductivity, 2003

ABSTRACT As a first approach, a wire with a single Nb3Al filament has been manufactured to study ... more ABSTRACT As a first approach, a wire with a single Nb3Al filament has been manufactured to study the rapid heating and quenching parameters. A reel-to-reel continuous rapid quenching apparatus has been designed and fabricated which will be able to produce some hundred meters of wire. The heating temperature is monitored by an infra-red two colours detector. Structural characterization of Nb3Al wires has been investigated by means of X-ray diffraction. Due to the absence of stabilizing Cu, superconducting transport properties were estimated by Bean formula as a function of a background magnetic field up to 10 T, while hysteresis losses were measured by vibrating sample magnetometer facility.

Nuclear Fusion, 1997

Over the last few years, a great deal of effort has been devoted to solving the problem of power ... more Over the last few years, a great deal of effort has been devoted to solving the problem of power and particle handling in divertors, which has been recognized as a critical issue for the operation of a magnetic fusion reactor. In particular, the choice of materials for plasma facing components has been examined with a view to developing heat and erosion resistant materials for divertor target plates. A large database on the behaviour of low-2 (carbon or beryllium) materials in tokamaks is available, while for high-2 materials there is little experience in the present generation of magnetic fusion devices. Frascati Tokamak Upgrade (FTU), a high field compact tokamak, has devoted part of its experimental campaign to studying the plasma characteristics when its limiter material is changed from the usual Inconel (nickel) to molybdenum and tungsten. Siliconization of the machine has also allowed the comparison of plasma performance when a relatively low-2 (silicon) ion is the dominant impurity. In this article, results are reported concerning the plasma operation, the differences in plasma characteristics and radiation losses, the impurity generation mechanisms and the relative impurity concentrations in the core plasma. A simulation of the experimental results, made with a self-consistent edge-core coupled model is presented, in order to provide evidence of the main physics mechanisms responsible for the observed behaviour.

Journal of Nuclear Materials, 1995

We present the first results of the program for the characterization of the thermal flux on the F... more We present the first results of the program for the characterization of the thermal flux on the FTU poloidal iimiter during disruptions. Data on power fluxes are obtained by using an infrared detector and a set of thermocouples. Two peaks in the limiter thermal load, corresponding to the thermal (up to 500 MW/m 2) and magnetic quenches, are well resolved by the infrared detector allowing the time correlation with other fast diagnostic measurements. The dependence on the main plasma parameters of the intensity and time evolution of the thermal flux to the limiter is discussed.

Journal of Nuclear Materials, 2008

IEEE Transactions on Appiled Superconductivity, 2005

The evaluation of electrical coupling parameters in multistrand cables is a fundamental prerequis... more The evaluation of electrical coupling parameters in multistrand cables is a fundamental prerequisite for the calculation of current distribution and ac-losses in superconducting cables. The theoretical evaluation of these parameters requires a detailed description of the cable geometry. A code for the geometric description of generic multistrand multistage cables and for the calculation of the strand self- and mutual inductance

International Journal of Modern Physics B, 2000

A complete characterisation of an Oxford Instruments Vibrating Sample Magnetometer (VSM) has been... more A complete characterisation of an Oxford Instruments Vibrating Sample Magnetometer (VSM) has been made in order to check the limits and the reproducibility of the system as well as the measurement accuracy. Several measurement cycles have then been carried out to check the extent of the difference between the actual sample temperature and the sensor reading, and the weight of this difference on the magnetization data as a function of the temperature. Moreover an unexpected lowering of a reference signal has been observed at low temperatures, most probably due to shielding currents in the structure; this effect influences the sample signals, and has to be taken into account during data analysis. Being the magnetization a relative measurement, a great attention must be paid to the calibration procedure. Calibrations with 99.999% pure Nickel and Palladium, which have magnetization signals two order of magnitude apart, give comparable calibration constants. We observed that in order to ...

Fusion Engineering and Design, 2009

In the IFMIF (International Fusion Material Irradiation Facility) facility a rapid temperature in... more In the IFMIF (International Fusion Material Irradiation Facility) facility a rapid temperature increase in the flowing Lithium during its transit under the proton beam is expected. Enhanced erosion, caused by pitting phenomena, or flow instabilities may arise from the sudden heating. A side experiment, to develop experience on these potential problems, to be carried on during the EVEDA (Engineering Validation Engineering Design Activities) phase is strongly needed in view of the IFMIF facility realization. In the paper an analysis of a possible simplified experiment performed on liquid flowing lithium target heated by an electron beam source is discussed, mainly concerning dimensioning, scaling effects, detailed calculations of the electron heating deposition scenarios and experiment significance.

Problems of Atomic Science and Technology, Ser. Thermonuclear Fusion

Fusion-fission hybrid systems (FFH) represent a coupling between a fusion device and a subcritica... more 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 potentialities of a FFH based on a tokamak device characterized by high magnetic field (B > 9 T) and high-density plasma (n > 1014 cm–3) have been evaluated. During the years high magnetic field compact tokamaks have been designed, built and operated. Thanks to their characteristics, such as compactness, high field and high density plasma, these devices can produce intense neutron fluxes, and therefore are good candidates to be incorporated in FFH while operating in a sub-ignited regime. An additional advantage is that their design is based on relatively simple existing technology. In this work, a coupling between a tokamak (operating in DD-mode) and a subcritical molten salt fission blanket has been proposed. Molten salt reactor could be adapted for this purpose and could help the hybrid system to increase its energy balance. A model with a molten salt fission blanket (keff = 0.92, P = 95 MW) instead of the lithium one, has been considered and studied in terms of neutronic evaluations. Presented preliminary numerical calculations based on a neutron Monte-Carlo code confirm the potentialities of the system.

Rapporto Tecnico Accordo di Programma ENEA-MSE: tema di ricerca "Nuovo nucleare da fissione" Reat... more Rapporto Tecnico Accordo di Programma ENEA-MSE: tema di ricerca "Nuovo nucleare da fissione" Reattori nucleari ad acqua Schermaggio IRIS Metodi deterministici per la neutronica This work is the extension to a full reactor geometry of a former activity limited to shielding calculation up to the reactor vessel for the IRIS (International Reactor Innovative and Secure) project The IRIS is a advanced medium size Light Water Reactor (LWR), being developed through an international partnership for a near term deployment to offer a simple nuclear plant with outstanding safety, attractive economics and enhanced proliferation resistance characteristics. It provides a viable bridge to Generation IV reactors and has excellent capability to satisfy in the near/mid-term timeframe the International Global Nuclear Energy Partnership (GNEP-I) requirements for small-scale reactors. The present document extends the Shielding activity carried out during the year 2009 at ENEA by means of the TORT (Three-dimensional discrete ordinates neutron/photon) ver. 3,2 deterministic code, The initial objectives of the analysis were the evaluation of the fast neutron fluence above 1 MeV (and DpA) on Pressure Vessel and a raw estimation of activation in the "first" concrete, Finally a full geometrical description has been performed in order to evaluate doses in the control room during normal operation. Note Copia n.

Rapporto Tecnico Accordo di Programma ENEA-MSE: tema di ricerca "Nuovo nucleare da fissione" Reat... more Rapporto Tecnico Accordo di Programma ENEA-MSE: tema di ricerca "Nuovo nucleare da fissione" Reattori nucleari ad acqua Schermaggio IRIS Metodi deterministici per la neutronica This work is the extension to a full reactor geometry of a former activity limited to shielding calculation up to the reactor vessel for the IRIS (International Reactor Innovative and Secure) project The IRIS is a advanced medium size Light Water Reactor (LWR), being developed through an international partnership for a near term deployment to offer a simple nuclear plant with outstanding safety, attractive economics and enhanced proliferation resistance characteristics. It provides a viable bridge to Generation IV reactors and has excellent capability to satisfy in the near/mid-term timeframe the International Global Nuclear Energy Partnership (GNEP-I) requirements for small-scale reactors. The present document extends the Shielding activity carried out during the year 2009 at ENEA by means of the TORT (Three-dimensional discrete ordinates neutron/photon) ver. 3,2 deterministic code, The initial objectives of the analysis were the evaluation of the fast neutron fluence above 1 MeV (and DpA) on Pressure Vessel and a raw estimation of activation in the "first" concrete, Finally a full geometrical description has been performed in order to evaluate doses in the control room during normal operation. Note Copia n.

Fusion Technology 1994, 1995

A simple 3D algorithm is used to minimise heat load variation on a plasma facing component for a ... more A simple 3D algorithm is used to minimise heat load variation on a plasma facing component for a given e-folding length of the power flowing in the scrape-off layer of a tokamak machine. Heat load peaking factors not larger than 2 are obtained for the geometry of the FTU machine. Problems arising when shadowing between different components is considered are discussed.

Progress in Nuclear Energy

Thermal oils are nowadays widely used as heat transfer fluids or cooling media in industrial and ... more Thermal oils are nowadays widely used as heat transfer fluids or cooling media in industrial and energy production plants. Currently, very few data are available about their thermal stability in function of the operating temperatures, which is a crucial parameter to estimate oil structural changes and their possible effects the maximum fluids lifetime. The present work is concerned with ageing tests on a commercially used thermal oil at temperatures higher than the nominal working ones, including a full post-test characterization. At this aim, a dedicated experimental setup was designed and constructed to study the degradation kinetics, and to qualitatively and quantitatively analyze the released gases. As a result, the kinetic parameters were estimated, along with the related changes in the oil thermos-physical properties.

Problems of Atomic Science and Technology, Ser. Thermonuclear Fusion

The full development of a multi-disks uranium target is described, including neutron production a... more The full development of a multi-disks uranium target is described, including neutron production analysis, power deposition distributions, thermo-mechanical simulations and cooling schemes. A detailed material choice and a geometrical optimization were carried on in order to maximize the neutron production. (authors)

17th IEEE/NPSS Symposium Fusion Engineering (Cat. No.97CH36131), 1998

The paper presents a general overview of the Frascati Tokamak Upgrade (FTU) machine operation in ... more The paper presents a general overview of the Frascati Tokamak Upgrade (FTU) machine operation in the last two years. About 3500 pulses were performed (mostly in D2) with a toroidal field between 2.5 and 8 Tesla and a plasma current between 0.35-1.3 MA, according to the experimental programmes. An availability analysis of the FTU plant was performed, which pointed out

AIP Conference Proceedings, 2012

The so called Hybrid (Fusion-Fission) Reactors seem to be a realistic alternative to the drawback... more The so called Hybrid (Fusion-Fission) Reactors seem to be a realistic alternative to the drawbacks of both a pure Fusion and/or a pure Fission reactor; this alternative could also guarantee a "substantial" destruction of the transuranic nuclear waste or production of nuclear combustible. So far, several different hypothesis have been proposed for this type of reactor, all of them based on very advanced and hypothetic fusion scenarios. In the present paper we propose two possible compact (R = 2.5-2.9 m; a = 0.73-0.8 m) high toroidal field (BT = 8.5-7.0 T; Ip = 8-6.8 MA) Tokamaks (based or not on superconductors) to perform a robust and "economic" experiment, propaedeutic to the definitive design of the reactor, where the problems connected with the integration of a Tokamak device with a Fission device can be tested on a realistic base. On both solutions the total fusion power will be of the order of 100 MW and the14 MeV neutron density power of the order of 0.5-1 MW/m2.

Volume 3: Next Generation Reactors and Advanced Reactors; Nuclear Safety and Security, 2014

ABSTRACT The electricity production systems, especially those based on nuclear fission, are incre... more ABSTRACT The electricity production systems, especially those based on nuclear fission, are increasingly facing more tight constraints and are subjected to more deep analyses based on the three aspects of economical sustainability, environmental sustainability and social sustainability. Nuclear Reactors future development has been outlined in the framework of the GIF (Generation IV International Forum), where the Lead Fast Reactor (LFR) is placed among the most promising innovative solutions. Many aspects of LFR offer a huge improvement from different points of view. The non pressurization of the system and the absence of sources of hazardous chemical potential energy enhances consistently its safety aspects, improving the perception of inherent safety of the Generation IV (G4) reactors in the public opinion. At the moment, due to the abundance of the new fossil resources, the competitiveness of Nuclear Power Plants is severely challenged, this aspect representing the most difficult to manage, besides the public acceptability. Moreover, for G4 reactors, an additional “cost premium” associated with the innovative technological concept has to be taken into account. Conversely, looking at the mid-term future, the real economical comparison has to be performed considering as competing sources, according to the IPCC recommendations and constraints enacted by the European Community, only CO2 free sources. In this context, economical competitiveness could be regained depending on the “cost premium” to be added to fossil fuels to become CO2 free, through the improvement of the carbon separation and storage techniques. The intrinsic lead properties (e.g.: low absorption cross section) permit to easily design LFR flexible cores, optimized with respect to a number of possible goals, as a long-lived core with minimal reactivity swing intended for battery concepts, or what is called an “adiabatic” core. where the entire Pu and MA inventory in the spent fuel can be indefinitely reused in a closed fuel cycle. The latter option allows to limit the waste throughput to the fission products only (along with the – unavoidable – losses from fuel reprocessing), and to benefit of natural resources minimization. These are both specific Generation IV goals envisioned to reach nuclear energy sustainability. An overall fuel cycle balance in a scenario with a step by step introduction of LFR reactors fleet grown in a specific geographical area, is in details analyzed in [1] and presented in this conference.

Italy is a country where a long tradition of studies both in the fission and fusion field is cons... more Italy is a country where a long tradition of studies both in the fission and fusion field is consolidated; nevertheless a strong public opinion concerned with the destination of the Spent Nuclear Fuel hinders the development of nuclear power. The possibility to a severe reduction of the NSF mass generated from a fleet of nuclear reactors employing an hypothetical fusionfission hybrid reactor has been investigated in the Italian framework. The possibility to produce nuclear fuel for the fission nuclear reactors with the hybrid reactor was analyzed too.

Smart Materials and Structures, 2007

Fiber optics with a photo-imprinted Bragg grating have been studied for potential use as temperat... more Fiber optics with a photo-imprinted Bragg grating have been studied for potential use as temperature sensors in cryogenic applications. Sensors were coupled with different metallic materials to improve the measurement sensitivity in the very low temperature region, i.e. 4.2-30 K. Various coatings were deposited on the external fiber surface, and full characterization of the tested sensors is given in the paper.

Plasma Physics and Controlled Fusion, 1997

Physica C: Superconductivity, 2003

ABSTRACT As a first approach, a wire with a single Nb3Al filament has been manufactured to study ... more ABSTRACT As a first approach, a wire with a single Nb3Al filament has been manufactured to study the rapid heating and quenching parameters. A reel-to-reel continuous rapid quenching apparatus has been designed and fabricated which will be able to produce some hundred meters of wire. The heating temperature is monitored by an infra-red two colours detector. Structural characterization of Nb3Al wires has been investigated by means of X-ray diffraction. Due to the absence of stabilizing Cu, superconducting transport properties were estimated by Bean formula as a function of a background magnetic field up to 10 T, while hysteresis losses were measured by vibrating sample magnetometer facility.

Nuclear Fusion, 1997

Over the last few years, a great deal of effort has been devoted to solving the problem of power ... more Over the last few years, a great deal of effort has been devoted to solving the problem of power and particle handling in divertors, which has been recognized as a critical issue for the operation of a magnetic fusion reactor. In particular, the choice of materials for plasma facing components has been examined with a view to developing heat and erosion resistant materials for divertor target plates. A large database on the behaviour of low-2 (carbon or beryllium) materials in tokamaks is available, while for high-2 materials there is little experience in the present generation of magnetic fusion devices. Frascati Tokamak Upgrade (FTU), a high field compact tokamak, has devoted part of its experimental campaign to studying the plasma characteristics when its limiter material is changed from the usual Inconel (nickel) to molybdenum and tungsten. Siliconization of the machine has also allowed the comparison of plasma performance when a relatively low-2 (silicon) ion is the dominant impurity. In this article, results are reported concerning the plasma operation, the differences in plasma characteristics and radiation losses, the impurity generation mechanisms and the relative impurity concentrations in the core plasma. A simulation of the experimental results, made with a self-consistent edge-core coupled model is presented, in order to provide evidence of the main physics mechanisms responsible for the observed behaviour.

Journal of Nuclear Materials, 1995

We present the first results of the program for the characterization of the thermal flux on the F... more We present the first results of the program for the characterization of the thermal flux on the FTU poloidal iimiter during disruptions. Data on power fluxes are obtained by using an infrared detector and a set of thermocouples. Two peaks in the limiter thermal load, corresponding to the thermal (up to 500 MW/m 2) and magnetic quenches, are well resolved by the infrared detector allowing the time correlation with other fast diagnostic measurements. The dependence on the main plasma parameters of the intensity and time evolution of the thermal flux to the limiter is discussed.

Journal of Nuclear Materials, 2008

IEEE Transactions on Appiled Superconductivity, 2005

The evaluation of electrical coupling parameters in multistrand cables is a fundamental prerequis... more The evaluation of electrical coupling parameters in multistrand cables is a fundamental prerequisite for the calculation of current distribution and ac-losses in superconducting cables. The theoretical evaluation of these parameters requires a detailed description of the cable geometry. A code for the geometric description of generic multistrand multistage cables and for the calculation of the strand self- and mutual inductance

International Journal of Modern Physics B, 2000

A complete characterisation of an Oxford Instruments Vibrating Sample Magnetometer (VSM) has been... more A complete characterisation of an Oxford Instruments Vibrating Sample Magnetometer (VSM) has been made in order to check the limits and the reproducibility of the system as well as the measurement accuracy. Several measurement cycles have then been carried out to check the extent of the difference between the actual sample temperature and the sensor reading, and the weight of this difference on the magnetization data as a function of the temperature. Moreover an unexpected lowering of a reference signal has been observed at low temperatures, most probably due to shielding currents in the structure; this effect influences the sample signals, and has to be taken into account during data analysis. Being the magnetization a relative measurement, a great attention must be paid to the calibration procedure. Calibrations with 99.999% pure Nickel and Palladium, which have magnetization signals two order of magnitude apart, give comparable calibration constants. We observed that in order to ...

Fusion Engineering and Design, 2009

In the IFMIF (International Fusion Material Irradiation Facility) facility a rapid temperature in... more In the IFMIF (International Fusion Material Irradiation Facility) facility a rapid temperature increase in the flowing Lithium during its transit under the proton beam is expected. Enhanced erosion, caused by pitting phenomena, or flow instabilities may arise from the sudden heating. A side experiment, to develop experience on these potential problems, to be carried on during the EVEDA (Engineering Validation Engineering Design Activities) phase is strongly needed in view of the IFMIF facility realization. In the paper an analysis of a possible simplified experiment performed on liquid flowing lithium target heated by an electron beam source is discussed, mainly concerning dimensioning, scaling effects, detailed calculations of the electron heating deposition scenarios and experiment significance.

Problems of Atomic Science and Technology, Ser. Thermonuclear Fusion

Fusion-fission hybrid systems (FFH) represent a coupling between a fusion device and a subcritica... more 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 potentialities of a FFH based on a tokamak device characterized by high magnetic field (B > 9 T) and high-density plasma (n > 1014 cm–3) have been evaluated. During the years high magnetic field compact tokamaks have been designed, built and operated. Thanks to their characteristics, such as compactness, high field and high density plasma, these devices can produce intense neutron fluxes, and therefore are good candidates to be incorporated in FFH while operating in a sub-ignited regime. An additional advantage is that their design is based on relatively simple existing technology. In this work, a coupling between a tokamak (operating in DD-mode) and a subcritical molten salt fission blanket has been proposed. Molten salt reactor could be adapted for this purpose and could help the hybrid system to increase its energy balance. A model with a molten salt fission blanket (keff = 0.92, P = 95 MW) instead of the lithium one, has been considered and studied in terms of neutronic evaluations. Presented preliminary numerical calculations based on a neutron Monte-Carlo code confirm the potentialities of the system.

Rapporto Tecnico Accordo di Programma ENEA-MSE: tema di ricerca "Nuovo nucleare da fissione" Reat... more Rapporto Tecnico Accordo di Programma ENEA-MSE: tema di ricerca "Nuovo nucleare da fissione" Reattori nucleari ad acqua Schermaggio IRIS Metodi deterministici per la neutronica This work is the extension to a full reactor geometry of a former activity limited to shielding calculation up to the reactor vessel for the IRIS (International Reactor Innovative and Secure) project The IRIS is a advanced medium size Light Water Reactor (LWR), being developed through an international partnership for a near term deployment to offer a simple nuclear plant with outstanding safety, attractive economics and enhanced proliferation resistance characteristics. It provides a viable bridge to Generation IV reactors and has excellent capability to satisfy in the near/mid-term timeframe the International Global Nuclear Energy Partnership (GNEP-I) requirements for small-scale reactors. The present document extends the Shielding activity carried out during the year 2009 at ENEA by means of the TORT (Three-dimensional discrete ordinates neutron/photon) ver. 3,2 deterministic code, The initial objectives of the analysis were the evaluation of the fast neutron fluence above 1 MeV (and DpA) on Pressure Vessel and a raw estimation of activation in the "first" concrete, Finally a full geometrical description has been performed in order to evaluate doses in the control room during normal operation. Note Copia n.

Rapporto Tecnico Accordo di Programma ENEA-MSE: tema di ricerca "Nuovo nucleare da fissione" Reat... more Rapporto Tecnico Accordo di Programma ENEA-MSE: tema di ricerca "Nuovo nucleare da fissione" Reattori nucleari ad acqua Schermaggio IRIS Metodi deterministici per la neutronica This work is the extension to a full reactor geometry of a former activity limited to shielding calculation up to the reactor vessel for the IRIS (International Reactor Innovative and Secure) project The IRIS is a advanced medium size Light Water Reactor (LWR), being developed through an international partnership for a near term deployment to offer a simple nuclear plant with outstanding safety, attractive economics and enhanced proliferation resistance characteristics. It provides a viable bridge to Generation IV reactors and has excellent capability to satisfy in the near/mid-term timeframe the International Global Nuclear Energy Partnership (GNEP-I) requirements for small-scale reactors. The present document extends the Shielding activity carried out during the year 2009 at ENEA by means of the TORT (Three-dimensional discrete ordinates neutron/photon) ver. 3,2 deterministic code, The initial objectives of the analysis were the evaluation of the fast neutron fluence above 1 MeV (and DpA) on Pressure Vessel and a raw estimation of activation in the "first" concrete, Finally a full geometrical description has been performed in order to evaluate doses in the control room during normal operation. Note Copia n.

Fusion Technology 1994, 1995

A simple 3D algorithm is used to minimise heat load variation on a plasma facing component for a ... more A simple 3D algorithm is used to minimise heat load variation on a plasma facing component for a given e-folding length of the power flowing in the scrape-off layer of a tokamak machine. Heat load peaking factors not larger than 2 are obtained for the geometry of the FTU machine. Problems arising when shadowing between different components is considered are discussed.