Fusion: a true challenge for an enormous reward

Ongena, J.

doi:10.1051/epjconf/201818900015

Cited by 6 publications

(4 citation statements)

References 19 publications

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“…As an important aspect, nuclear fusion is potentially cleaner than fission as it does not produce long-living radioactive waste and its fuel cycle uses abundant materials (namely deuterium and lithium). In this perspective, fusion may produce electricity in an inherently safe and inexhaustible way, complying with the requirements for the environmental sustainability of the future energy policies [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

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Classical Thermodynamic Analysis of D-Based Nuclear Fusion Reactions: The Role of Entropy

Tosti

2023

Energies

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In this work, the feasibility of nuclear processes is studied via classical thermodynamics by assessing the change in entropy, a parameter that has so far been neglected in the analysis of these reactions. The contribution of the entropy to the reaction spontaneity plays a different role in the fission and fusion reactions. In particular, in fusion reactions the temperature acts as a very powerful amplifier of the entropic term (−T ΔS) that, at the temperature of tokamaks (millions Kelvin), may significantly reduce the thermodynamic spontaneity of these processes. A new approach is followed for assessing the feasibility of the D-based reactions of interest for the magnetically confined nuclear fusion through the investigation of the effect of the temperature on both kinetics and thermodynamics. The results confirm that the deuterium–tritium reaction is the most promising fusion reaction to be realized in tokamak devices. At the temperature of 1.5 × 108 K (≈13 keV), the DT reaction exhibits a large thermodynamic spontaneity (ΔG = 16.0 MeV) and its reactivity is of the order of 10−22 m3/s, a value capable of guaranteeing the tritium burning rate needed to operate the nuclear plants under tritium self-sufficiency conditions and with a net energy production. The other results show that at the tokamaks’ temperature the two branches of the DD reaction exhibit a modest spontaneity (ΔG around −2 MeV) coupled to very low reactivity values (10−24 m3/s). The temperature rise that could be aimed to increase the reactivity is however ineffective to improve the reaction feasibility since it would augment the entropic term as well, thus shifting the ΔG towards positive values. The D3He reaction is soundly spontaneous at the tokamaks’ temperature (ΔG values of −17.2 MeV) while its kinetics is close to that of the DD reactions, which are at least two orders of magnitude lower than that of the DT reaction.

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Section: Introductionmentioning

confidence: 99%

“…Values of the Maxwell-averaged reactivities "σ v" of D-based reactions calculated from literature[26,27]. "DT" is indicating the reaction(12), "DD -> p" the reaction(13), "DD -> n" the reaction(14) and "D3 He" the reaction(15).…”

mentioning

confidence: 99%

Classical Thermodynamic Analysis of D-Based Nuclear Fusion Reactions: The Role of Entropy

Tosti

2023

Energies

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“…The fusion project is very ambitious: it aims to produce electricity in a substantially CO2-free way, complying with the requirements for environmental sustainability of future energy policies, as well as being inexhaustible and inherently safe [2][3][4] . Despite its outstanding potential impact on the energy sector, nuclear fusion R&D programs have to face very tricky hurdles both in physics and technology [5][6][7][8] .…”

Section: Introductionmentioning

confidence: 99%

Spontaneity of nuclear fusion: a qualitative analysis via classical thermodynamics

Tosti¹

2021

Open Res Europe

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Background: So far the feasibility of nuclear reactions has been studied only through the evaluation of the reaction rate, which gives us information about the kinetics, while the thermodynamic analysis has been limited to evaluations of the change in enthalpy without any consideration of the change in entropy. Methods: This work examines the thermodynamics of nuclear fusion reactions through a simplified approach. The analysis introduces the thermodynamic study of fission and fusion reactions through their comparison with a chemical process. Results: The main result is that fission reactions are always spontaneous (ΔG < 0) since a lot of energy is released in the form of heat and the system moves spontaneously towards a more disordered state. In contrast, fusion reactions are spontaneous only when the enthalpic contribution of the change in Gibbs free energy overcomes the entropic contribution. This condition is verified when the temperature of the process is below a characteristic value T*, calculated as the ratio between the energy corresponding to the mass defect and the change of entropy of the fusion reaction. Conclusions: Due to the unavailability of data related to entropy changes in fusion reactions, only a qualitative thermodynamic analysis has been carried out. Through such analysis, the influence of the operating conditions over the spontaneity of fusion processes has been discussed. The final considerations emphasize the role of the thermodynamics analysis that should be implemented in the current studies that, so far, have been mainly based on the assessment of the reaction rate and exothermicity of fusion reactions.

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“…The fusion project is very ambitious: it aims to produce electricity in a substantially CO2-free way, complying with the requirements for environmental sustainability of future energy policies, as well as being inexhaustible and inherently safe 2 – 4 . Despite its outstanding potential impact on the energy sector, nuclear fusion R&D programs have to face very tricky hurdles both in physics and technology 5 – 8 .…”

Section: Introductionmentioning

confidence: 99%

Spontaneity of nuclear fusion: a qualitative analysis via classical thermodynamics

Tosti¹

2021

Open Res Europe

View full text Add to dashboard Cite

Background: So far the feasibility of nuclear reactions has been studied only through the evaluation of the reaction rate, which gives us information about the kinetics, while the thermodynamic analysis has been limited to evaluations of the change in enthalpy without any consideration of the change in entropy. Methods: This work examines the thermodynamics of nuclear fusion reactions through a simplified approach. The analysis introduces the thermodynamic study of fission and fusion reactions through their comparison with a chemical process. Results: The main result is that fission reactions are always spontaneous (ΔG < 0) since a lot of energy is released in the form of heat and the system moves spontaneously towards a more disordered state. In contrast, fusion reactions are spontaneous only when the enthalpic contribution of the change in Gibbs energy overcomes the entropic contribution. This condition is verified when the temperature of the process is below a characteristic value T*, calculated as the ratio between the energy corresponding to the mass defect and the change of entropy of the fusion reaction. Conclusions: Due to the unavailability of data related to entropy changes in fusion reactions, only a qualitative thermodynamic analysis has been carried out. Through such analysis, the influence of the operating conditions over the spontaneity of fusion processes has been discussed. The final considerations emphasize the role of the thermodynamics analysis that should be implemented in the current studies that, so far, have been mainly based on the assessment of the reaction rate and exothermicity of fusion reactions.

show abstract

Fusion: a true challenge for an enormous reward

Cited by 6 publications

References 19 publications

Classical Thermodynamic Analysis of D-Based Nuclear Fusion Reactions: The Role of Entropy

Classical Thermodynamic Analysis of D-Based Nuclear Fusion Reactions: The Role of Entropy

Spontaneity of nuclear fusion: a qualitative analysis via classical thermodynamics

Spontaneity of nuclear fusion: a qualitative analysis via classical thermodynamics

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