Spallation – Neutrons Beyond Nuclear Fission

Despite research carried out around the world since the 1950s, no industrial application of fusion to energy production has yet succeeded, apart from nuclear weapons with the H-bomb, since this application does not aims at containing and controlling the reaction produced. There are, however, some other less mediated uses, such as neutron generators. The fusion of light nuclei releases enormous amounts of energy from the attraction between the nucleons due to the strong interaction (nuclear binding energy). Fusion it is with nuclear fission one of the two main types of nuclear reactions applied. The mass of the new atom obtained by the fusion is less than the sum of the masses of the two light atoms. In the process of fusion, part of the mass is transformed into energy in its simplest form: heat. This loss is explained by the Einstein known formula E=mc2. Unlike nuclear fission, the fusion products themselves (mainly helium 4) are not radioactive, but when the reaction is used to emit fast neutrons, they can transform the nuclei that capture them into isotopes that some of them can be radioactive. In order to be able to start and to be maintained with the success the nuclear fusion reactions, it is first necessary to know all this reactions very well. This means that it is necessary to know both the main reactions that may take place in a nuclear reactor and their sense and effects. The main aim is to choose and coupling the most convenient reactions, forcing by technical means for their production in the reactor. Taking into account that there are a multitude of possible variants, it is necessary to consider in advance the solutions that we consider them optimal. The paper takes into account both variants of nuclear fusion, and cold and hot. For each variant will be mentioned the minimum necessary specifications.

Download Full-text

Delayed nuclear fission

Physics of Particles and Nuclei ◽

10.1134/1.953123 ◽

1999 ◽

Vol 30 (6) ◽

pp. 666 ◽

Cited By ~ 9

Author(s):

V. I. Kuznetsov

Keyword(s):

Nuclear Fission

Download Full-text

The Age of Innocence

10.1093/oso/9780198827870.001.0001 ◽

2018 ◽

Cited By ~ 4

Author(s):

Roger H. Stuewer

Keyword(s):

Nuclear Physics ◽

Nuclear Reactions ◽

Alpha Decay ◽

Nuclear Fission ◽

Theoretical Physics ◽

Lise Meitner ◽

Artificial Radioactivity ◽

The Great Depression ◽

Nuclear Disintegration ◽

Quantum Mechanical Theory

Nuclear physics emerged as the dominant field in experimental and theoretical physics between 1919 and 1939, the two decades between the First and Second World Wars. Milestones were Ernest Rutherford’s discovery of artificial nuclear disintegration (1919), George Gamow’s and Ronald Gurney and Edward Condon’s simultaneous quantum-mechanical theory of alpha decay (1928), Harold Urey’s discovery of deuterium (the deuteron), James Chadwick’s discovery of the neutron, Carl Anderson’s discovery of the positron, John Cockcroft and Ernest Walton’s invention of their eponymous linear accelerator, and Ernest Lawrence’s invention of the cyclotron (1931–2), Frédéric and Irène Joliot-Curie’s discovery and confirmation of artificial radioactivity (1934), Enrico Fermi’s theory of beta decay based on Wolfgang Pauli’s neutrino hypothesis and Fermi’s discovery of the efficacy of slow neutrons in nuclear reactions (1934), Niels Bohr’s theory of the compound nucleus and Gregory Breit and Eugene Wigner’s theory of nucleus+neutron resonances (1936), and Lise Meitner and Otto Robert Frisch’s interpretation of nuclear fission, based on Gamow’s liquid-drop model of the nucleus (1938), which Frisch confirmed experimentally (1939). These achievements reflected the idiosyncratic personalities of the physicists who made them; they were shaped by the physical and intellectual environments of the countries and institutions in which they worked; and they were buffeted by the profound social and political upheavals after the Great War: the punitive postwar treaties, the runaway inflation in Germany and Austria, the Great Depression, and the greatest intellectual migration in history, which encompassed some of the most gifted experimental and theoretical nuclear physicists in the world.

Download Full-text

Improvements to the macroscopic-microscopic approach of nuclear fission

Physical Review C ◽

10.1103/physrevc.103.034617 ◽

2021 ◽

Vol 103 (3) ◽

Author(s):

Marc Verriere ◽

Matthew Ryan Mumpower

Keyword(s):

Nuclear Fission ◽

Microscopic Approach

Download Full-text

Rapid imaging of special nuclear materials for nuclear nonproliferation and terrorism prevention

Science Advances ◽

10.1126/sciadv.abg3032 ◽

2021 ◽

Vol 7 (21) ◽

pp. eabg3032

Author(s):

Jana Petrović ◽

Alf Göök ◽

Bo Cederwall

Keyword(s):

Nuclear Physics ◽

Imaging Modality ◽

Three Dimensional ◽

Nuclear Fission ◽

Machine Learning Techniques ◽

Nuclear Materials ◽

Prototype System ◽

Fast Time ◽

Gamma Emission ◽

Special Nuclear Materials

We introduce a neutron-gamma emission tomography (NGET) technique for rapid detection, three-dimensional imaging, and characterization of special nuclear materials like weapons-grade plutonium and uranium. The technique is adapted from fundamental nuclear physics research and represents a previously unexplored approach to the detection and imaging of small quantities of these materials. The method is demonstrated on a radiation portal monitor prototype system based on fast organic scintillators, measuring the characteristic fast time and energy correlations between particles emitted in nuclear fission processes. The use of these correlations in real time in conjunction with modern machine learning techniques provides unprecedented imaging efficiency and high spatial resolution. This imaging modality addresses global security threats from terrorism and the proliferation of nuclear weapons. It also provides enhanced capabilities for addressing different nuclear accident scenarios and for environmental radiological surveying.

Download Full-text

The SPES3 Facility for Testing an Integral Layout SMR: BDBE Simulation Analysis

ASME 2011 Small Modular Reactors Symposium ◽

10.1115/smr2011-6614 ◽

2011 ◽

Author(s):

Roberta Ferri ◽

Andrea Achilli ◽

Cinzia Congiu ◽

Gustavo Cattadori ◽

Fosco Bianchi ◽

...

Keyword(s):

Simulation Analysis ◽

Nuclear Fission ◽

Sensitivity Analyses ◽

Medium Size ◽

Design Calculation ◽

Pressurized Water ◽

Pressure Equalization ◽

Plant Safety ◽

Design Basis ◽

Safety Features

The SPES3 facility is being built at the SIET laboratories, in the frame of an R&D program on Nuclear Fission, led by ENEA and funded by the Italian Ministry of Economic Development. The facility is based on the IRIS reactor design, an advanced medium size, integral layout, pressurized water reactor, based on the proven technology of PWR with an innovative configuration and safety features suitable to cope with Loss of Coolant Accidents through a dynamic coupling of the primary and containment systems. SPES3 is suitable to test the plant response to postulated Design and Beyond Design Basis Events, providing experimental data for code validation and plant safety analysis. It reproduces the primary, secondary and containment systems of the reactor with 1:100 volume scale, full elevation, prototypical fluid and thermal-hydraulic conditions. A design-calculation feedback process, based on the comparison between IRIS and SPES3 simulations, performed respectively by FER, with GOTHIC and RELAP5 coupled codes, and by SIET, with RELAP5 code, led to reduce the differences in the two plants behaviour, versus a 2-inch equivalent DVI line DEG break, considered the most challenging LOCA for the IRIS plant. Once available the final design of SPES3, further calculations were performed to investigate Beyond Design Basis Events, where the intervention of the Passive Containment Condenser is fundamental for the accident recovery. Sensitivity analyses showed the importance of the PCC actuation time, to limit the containment pressure, to reach an early pressure equalization between the primary and containment systems and to allow passive water transfer from the containment to the RPV, enhanced by the ADS Stage-II opening.

Download Full-text