New Burnup Calculation System for Fusion-Fission Hybrid System
International Nuclear Information System (INIS)
Investigation of nuclear waste incineration has positively been carried out worldwide from the standpoint of environmental issues. Some candidates such as ADS, FBR are under discussion for possible incineration technology. Fusion reactor is one of such technologies, because it supplies a neutron-rich and volumetric irradiation field, and in addition the energy is higher than nuclear reactor. However, it is still hard to realize fusion reactor right now, as well known. An idea of combination of fusion and fission concepts, so-called fusion-fission hybrid system, was thus proposed for the nuclear waste incineration. Even for a relatively lower plasma condition, neutrons can be well multiplied by fission in the nuclear fuel, tritium is thus bred so as to attain its self-sufficiency, enough energy multiplication is then expected and moreover nuclear waste incineration is possible. In the present study, to realize it as soon as possible with the presently proven technology, i.e., using ITER model with the achieved plasma condition of JT60 in JAEA, Japan, a new calculation system for fusion-fission hybrid reactor including transport by MCNP and burnup by ORIGEN has been developed for the precise prediction of the neutronics performance. The author's group already has such a calculation system developed by them. But it had a problem that the cross section libraries in ORIGEN did not have a cross section library, which is suitable specifically for fusion-fission hybrid reactors. So far, those for FBR were approximately used instead in the analysis. In the present study, exact derivation of the collapsed cross section for ORIGEN has been investigated, which means it is directly evaluated from calculated track length by MCNP and point-wise nuclear data in the evaluated nuclear data file like JENDL-3.3. The system realizes several-cycle calculation one time, each of which consists of MCNP criticality calculation, MCNP fixed source calculation with a 3-dimensional precise
Fusion--fission neutronics calculations for the laser solenoid
International Nuclear Information System (INIS)
Neutron transport calculations are presented for several laser solenoid blanket configurations containing fast-fission lattices of uranium and thorium. The presence of a small-bore pulsed magnet and a small first-wall radius results in unique neutronics characteristics relative to other fusion concepts. Parametric calculations were completed to determine the effects of increasing the pulsed magnet thickness and of varying other key blanket parameters. Attractive fissile breeding rates could be achieved for blankets with a wide range of energy multiplication under the constraints of a tritium breeding ratio of about unity and a pulsed magnet thickness of about 3 cm
International Nuclear Information System (INIS)
A set of computer programs is developed for the calculation of laser-driven fission-fusion microexplosions. Both nuclear and thermohydrodynamic processes are considered, as well as their coupling effects, without taking into account the laser interaction so far, but simulating it by a boundary pressure pulse that can be varied parametrically. Three different systems (BERTA, NORMA-CLARA, NORMA-LIBERTAS) have been developed upon different approaches. BERTA is an integrated code which takes into account both nuclear and hydrodynamic processes in a coupled but simplified way. NORMA calculates in detail the thermo-hydrodynamic evolution under given boundary pressure conditions and nuclear energy generation. CLARA is a discrete-ordinates time-dependent neutron transport code which works directly coupled with NORMA. LIBERTAS is a Monte Carlo time-dependent neutron transport code, also coupled to NORMA, which can be of interest for analysis of anomalous or stochastic situations. (orig.)
International Nuclear Information System (INIS)
Hybrid fusion-fission reactor has advantages of production of nuclear fuel and transmutation of long-life nuclear waste and having inherent safety, at the same time, demand is significantly reduced compare to the pure fusion reactor. Breeding blanket is the key part of the fusion-fission reactor and in the past, the uranium-plutonium blanket concept was widely investigated. Considering the problem of uranium-plutonium cycle and abundant in thorium in our country, in this work,a thorium-based breeding and MA (minor actinides) transmutation blanket concept was proposed and the preliminary neutronics calculation was discussed. One-dimensional transport and burnup calculation code BISONC and Monte-Carlo transport code MCNP were used to calculate the key parameters, such as tritium breeding ratio, production of 233U mass and power density,and so on. The fuel of 233U enrichment can be 3.65%. It is the foundation for optimization of the blanket. (authors)
Neutronics of Laser Fission-Fusion Systems
International Nuclear Information System (INIS)
Neutronics of Fission-Fusion microsystems inertially confined by Lasers are analysed by transport calculation, both stationary (DTF, TIHOC) and time dependent (TDA, TIHEX), discussing the results obtained for the basic parameters of the fission process (multiplication factor, neutron generation time and Rossi-∞). (Author) 14 refs
Burnup calculations of light water-cooled pressure tube blanket for a fusion-fission hybrid reactor
Energy Technology Data Exchange (ETDEWEB)
Zu, Tiejun, E-mail: tiejun@mail.xjtu.edu.cn; Wu, Hongchun; Zheng, Youqi; Cao, Liangzhi
2014-06-15
Highlights: • Detailed burnup calculations are performed on pressurized water cooled blankets with pressure tube assemblies. • The blanket is fueled with simple fuel, namely spent nuclear fuel discharged from light water reactors or natural uranium oxide. • The refueling strategies are proposed, and the uranium resource utilization rate can reach 5–6%. - Abstract: A fusion-fission hybrid reactor (FFHR) with pressure tube blanket has recently been proposed based on an ITER-type tokamak fusion neutron source and the well-developed pressurized water cooling technologies. In this paper, detailed burnup calculations are carried out on an updated blanket. Two different blankets respectively fueled with the spent nuclear fuel (SNF) discharged from light water reactors (LWRs) or natural uranium oxide is investigated. In the first case, a three-batch out-to-in refueling strategy is designed. In the second case, some SNF assemblies are loaded into the blanket to help achieve tritium self-sufficiency. And a three-batch in-to-out refueling strategies is adopted to realize direct use of natural uranium oxide fuel in the blanket. The results show that only about 80 tonnes of SNF or natural uranium are needed every 1500 EFPD (Equivalent Full Power Day) with a 3000 MWth output and tritium self-sufficiency (TBR > 1.15), while the required maximum fusion powers are lower than 500 MW for both the two cases. Based on the proposed refueling strategies, the uranium utilization rate can reach about 4.0%.
Burnup calculations of light water-cooled pressure tube blanket for a fusion-fission hybrid reactor
International Nuclear Information System (INIS)
Highlights: • Detailed burnup calculations are performed on pressurized water cooled blankets with pressure tube assemblies. • The blanket is fueled with simple fuel, namely spent nuclear fuel discharged from light water reactors or natural uranium oxide. • The refueling strategies are proposed, and the uranium resource utilization rate can reach 5–6%. - Abstract: A fusion-fission hybrid reactor (FFHR) with pressure tube blanket has recently been proposed based on an ITER-type tokamak fusion neutron source and the well-developed pressurized water cooling technologies. In this paper, detailed burnup calculations are carried out on an updated blanket. Two different blankets respectively fueled with the spent nuclear fuel (SNF) discharged from light water reactors (LWRs) or natural uranium oxide is investigated. In the first case, a three-batch out-to-in refueling strategy is designed. In the second case, some SNF assemblies are loaded into the blanket to help achieve tritium self-sufficiency. And a three-batch in-to-out refueling strategies is adopted to realize direct use of natural uranium oxide fuel in the blanket. The results show that only about 80 tonnes of SNF or natural uranium are needed every 1500 EFPD (Equivalent Full Power Day) with a 3000 MWth output and tritium self-sufficiency (TBR > 1.15), while the required maximum fusion powers are lower than 500 MW for both the two cases. Based on the proposed refueling strategies, the uranium utilization rate can reach about 4.0%
International Nuclear Information System (INIS)
The results of experiments carried out at GSI Darmstadt, LBNL Berkeley and RIKEN Tokyo on the synthesis of superheavy nuclei of Z = 104–113 in cold fusion reactions have been analyzed within the fusion-by-diffusion (FBD) model by using the fission barriers, ground-state masses, shell effects and deformations calculated with the Warsaw macroscopic–microscopic model. An empirical parametrization of the injection-point distance has been established for this new theoretical input to the FBD model that enables one to reproduce existing data with reasonable accuracy and predict synthesis cross sections and optimum bombarding energies in as yet unexplored cold fusion reactions. (paper)
International Nuclear Information System (INIS)
In this manual we describe the use of the FORIG computer code to solve isotope-generation and depletion problems in fusion and fission reactors. FORIG runs on a Cray-1 computer and accepts more extensive activation cross sections than ORIGEN2 from which it was adapted. This report is an updated and a combined version of the previous ORIGEN2 and FORIG manuals. 7 refs., 15 figs., 13 tabs
Revitalizing Fusion via Fission Fusion
Manheimer, Wallace
2001-10-01
Existing tokamaks could generate significant nuclear fuel. TFTR, operating steady state with DT might generate enough fuel for a 300 MW nuclear reactor. The immediate goals of the magnetic fusion program would necessarily shift from a study of advanced plasma regimes in larger sized devices, to mostly known plasmas regimes, but at steady state or high duty cycle operation in DT plasmas. The science and engineering of breeding blankets would be equally important. Follow on projects could possibly produce nuclear fuel in large quantity at low price. Although today there is strong opposition to nuclear power in the United States, in a 21st century world of 10 billion people, all of whom will demand a middle class life style, nuclear energy will be important. Concern over greenhouse gases will also drive the world toward nuclear power. There are studies indicating that the world will need 10 TW of carbon free energy by 2050. It is difficult to see how this can be achieved without the breeding of nuclear fuel. By using the thorium cycle, proliferation risks are minimized. [1], [2]. 1 W. Manheimer, Fusion Technology, 36, 1, 1999, 2.W. Manheimer, Physics and Society, v 29, #3, p5, July, 2000
Fission fusion hybrids- recent progress
Kotschenreuther, M.; Valanju, P.; Mahajan, S.; Covele, B.
2012-03-01
Fission-fusion hybrids enjoy unique advantages for addressing long standing societal acceptability issues of nuclear fission power, and can do this at a much lower level of technical development than a competitive fusion power plant- so it could be a nearer term application. For waste incineration, hybrids can burn intransigent transuranic residues (with the long lived biohazard) from light water reactors (LWRs) with far fewer hybrid reactors than a comparable system within the realm of fission alone. For fuel production, hybrids can produce fuel for ˜4 times as many LWRs with NO fuel reprocessing. For both waste incineration or fuel production, the most severe kind of nuclear accident- runaway criticality- can be excluded, unlike either fast reactors or typical accelerator based reactors. The proliferation risks for hybrid fuel production are, we strongly believe, far less than any other fuel production method, including today's gas centrifuges. US Thorium reserves could supply the entire US electricity supply for centuries. The centerpiece of the fuel cycle is a high power density Compact Fusion Neutron Source (major+minor radius ˜ 2.5-3.5 m), which is made feasible by the super-X divertor.
International Nuclear Information System (INIS)
Full text of publication follows: In order to meet the requirement of fusion reactor developing and nuclear waste treatment, a concept of fission-fusion neutron source has been proposed with LiD cylinder in heavy water region of China Advanced Research Reactor (CARR) by slow neutrons to transfer to fusion neutron. The principal is the reaction of 6Li(n,α) to produce energetic tritium ion with 2.739 MeV in LiD by slow neutron, which will be bombarding the deuteron of LiD to induce fusion reaction to produce 14 MeV neutron. The fusion reaction rate will increase with the accumulation of tritium in LiD by the reaction between tritium and deuteron recoils produced by 14 MeV neutrons. When the concentration of tritium in LiD reaches O.5 x 1022 T/cm3 and the fraction of fusion reaction induced by deuteron recoils with tritium approaches to 1, the 14 MeV neutron flux will be doubled and redoubled increasing to approach saturation in which the produced tritium at time t is exhausted by fusion reaction to keep the constant of tritium concentration in LiD. At this case the 14 MeV neutron production rate is too high, it has to decrease the slow neutron flux with decreasing CARR reactor power progressively when the fusion neutron flux approaches to presetting value, for example 3.5 x 1014 n/cm2 sec and will approach to saturation at the low level of neutron flux. This paper describes the principle of fission-fusion neutron source, including the production rate of fusion neutron, the accumulation rate and concentration of tritium, the fusion reaction rate induced by deuteron recoils with tritium, the 14 MeV neutron flux of inner surface of LiD cylinder in the heavy water region of CARR reactor without neutron depression and the influence factors. To consider the neutron depression an assembly of LiD rods in 20 x 20 cm with a centre hole in CARR reactor must be designed to optimize the fusion neutron flux in centre hole. (author)
Nuclear data for structural materials of fission and fusion reactors
International Nuclear Information System (INIS)
The document presents the status of nuclear reaction theory concerning optical model development, level density models and pre-equilibrium and direct processes used in calculation of neutron nuclear data for structural materials of fission and fusion reactors. 6 refs
Mechanisms of Mitochondrial Fission and Fusion
van der Bliek, Alexander M.; Shen, Qinfang; Kawajiri, Sumihiro
2013-01-01
Mitochondria continually change shape through the combined actions of fission, fusion, and movement along cytoskeletal tracks. The lengths of mitochondria and the degree to which they form closed networks are determined by the balance between fission and fusion rates. These rates are influenced by metabolic and pathogenic conditions inside mitochondria and by their cellular environment. Fission and fusion are important for growth, for mitochondrial redistribution, and for maintenance of a hea...
Fusion-fission dynamics in superheavy mass region
International Nuclear Information System (INIS)
In heavy nucleus collision experiments, the fusion-fission cross section is derived from counting mass-symmetric fission events. However, a discrepancy exists between the experimental and theoretical estimations of the fusion cross section. We attempt to clarify the origin of the discrepancy and remove it by performing a dynamical calculation. The trajectory calculation has been performed in three-dimensional coordinate space with the Langevin equation. (author)
Fusion materials irradiations at MaRIE'S fission fusion facility
International Nuclear Information System (INIS)
Los Alamos National Laboratory's proposed signature facility, MaRIE, will provide scientists and engineers with new capabilities for modeling, synthesizing, examining, and testing materials of the future that will enhance the USA's energy security and national security. In the area of fusion power, the development of new structural alloys with better tolerance to the harsh radiation environments expected in fusion reactors will lead to improved safety and lower operating costs. The Fission and Fusion Materials Facility (F3), one of three pillars of the proposed MaRIE facility, will offer researchers unprecedented access to a neutron radiation environment so that the effects of radiation damage on materials can be measured in situ, during irradiation. The calculated radiation damage conditions within the F3 match, in many respects, that of a fusion reactor first wall, making it well suited for testing fusion materials. Here we report in particular on two important characteristics of the radiation environment with relevancy to radiation damage: the primary knock-on atom spectrum and the impact of the pulse structure of the proton beam on temporal characteristics of the atomic displacement rate. With respect to both of these, analyses show that F3 has conditions that are consistent with those of a steady-state fusion reactor first wall.
Fusion materials irradiations at MaRIE's fission fusion facility
International Nuclear Information System (INIS)
Los Alamos National Laboratory's proposed signature facility, MaRIE, will provide scientists and engineers with new capabilities for modeling, synthesizing, examining, and testing materials of the future that will enhance the USA's energy security and national security. In the area of fusion power, the development of new structural alloys with better tolerance to the harsh radiation environments expected in fusion reactors will lead to improved safety and lower operating costs. The Fission and Fusion Materials Facility (F3), one of three pillars of the proposed MaRIE facility, will offer researchers unprecedented access to a neutron radiation environment so that the effects of radiation damage on materials can be measured in-situ, during irradiation. The calculated radiation damage conditions within the F3 match, in many respects, that of a fusion reactor first wall, making it well suited for testing fusion materials. Here we report in particular on two important characteristics of the radiation environment with relevancy to radiation damage: the primary knock-on atom spectrum and the impact of the pulse structure of the proton beam on temporal characteristics of the atomic displacement rate. With respect to both of these, analyses show the F3 has conditions that are consistent with those of a steady-state fusion reactor first wall.
Comparison of activation in fission and fusion spectrum neutron beams
International Nuclear Information System (INIS)
The materials used in the construction of fusion reactors have to satisfy a number of criterions, one of the important being low activation due to neutron irradiation. Experimental analysis of the activation of candidate materials for the first wall is performed with the irradiation of samples in various neutron fields, frequently in the field of a fission reactor. In the present work a calculation is performed to compare the expected activation of candidate materials intended to be used for the first wall in fusion reactors with the activation of a sample of the same material in a fission reactor beam. The FISPACT code is used for activation calculations. An investigation, to what extent the results of activation in a fission spectrum neutron beam, where most neutrons have energies of less than 2 MeV, mimic the real situation in a fusion reactor with the peak neutron energy around 14 MeV, is performed. (author)
Heavy ion fusion and fission reactions
International Nuclear Information System (INIS)
Various methods of probing the partial wave distribution are reviewed and new results using fission fragment angular distributions are discussed. Evidence that existing models of fusion reactions near-barrier and sub-barrier energies underestimate the mean-square spin values are presented. The dynamics of fusion reactions at higher energies are also discussed. The controversy over the interpretation of fission fragment and angular distributions are reviewed. Both statistical scission models and dynamical models with incomplete K mixing are discussed. New developments related to the effective moment of inertia of the saddlepoint shape are presented
Role of shell structure in the fusion-fission processes
International Nuclear Information System (INIS)
A comparison of the theoretical and experimental excitation functions of evaporation residues allows one the reveal an effect of the entrance channel and shell structure of reacting nuclei on the fusion-fission mechanism in heavy ion collisions at the near barrier energies. The same aim is purposed by study of dependence of the evaporation residues cross section on the isotope number of projectile or target. It is shown that competition between quasi-fission process and complete fusion may be drastic in case of collision of two massive nuclei and increases by increasing of the projectile energy even in collisions of the intermediate mass nuclei. The excitation functions for evaporation residues produced in the reaction leading to same compound nucleus were analyzed in the framework of the combined model based on the dinuclear system concept and advanced statistical model. It is shown that the competition of complete fusion with quasi fission process is strongly related to peculiarities of the entrance channel, i. e. to the intrinsic fusion barrier and the quasi fission barrier. The results of calculations are in good agreement with the experimental data on synthesis new superheavy elements is discussed. The effect of multi nucleons transfer and surface vibration of nuclei on the dynamics of capture and fusion process is considered. It is demonstrated that the peculiarities of the potential energy surface of interaction of two nuclei determine the spin distribution of compound nuclei and yield of fusion-fission reaction fragments. It is calculated as a function of their atomic and charge number, deformation parameters and binding energies. The decisive role of shell structure of initial nuclei and reaction products is shown by comparison of the calculated results with the experimental data
Opimization of fusion-driven fissioning systems
International Nuclear Information System (INIS)
Potential advantages of hybrid or fusion/fission systems can be exploited in different ways. With selection of the 238U--239Pu fuel cycle, we show that the system has greatest value as a power producer. Numerical examples of relative revenue from power production vs. 239Pu production are discussed, and possible plant characteristics described. The analysis tends to show that the hybrid may be more economically attractive than pure fusion systems
Fission--fusion systems: classification and critique
International Nuclear Information System (INIS)
A useful classification scheme for hybrid systems is described and some common features that the scheme makes apparent are pointed out. The early history of fusion-fission systems is reviewed. Some designs are described along with advantages and disadvantages of each. The extension to low and moderate Q devices is noted. (U.S.)
Parametric analyses of fusion-fission systems
International Nuclear Information System (INIS)
After a short review of the nuclear reactions relevant to fusion-fission systems the various types of blankets and characteristic model cases are presented. The fusion-fission system is modelled by its energy flow diagram. The system components and the system as a whole are characterized by 'component parameters' and 'system parameters' all of which are energy ratios. A cost estimate is given for the net energy delivered by the system, and a collection of formulas for the various energies flowing in the system in terms of the thermal energy delivered by the fusion part is presented. For sensitivity analysis four reference cases are defined which combine two plasma confinement schemes (mirror and tokamak) with two fissile fuel cycles (thorium-uranium and uranium-plutonium). The sensitivity of the critical plasma energy multiplication, of the circulating energy fraction, and of the energy cost with respect to changes of the component parameters is analysed. For the mirror case only superconducting magnets are considered, whereas two tokimak cases take into account both superconducting and normal-conducting coils. A section presenting relations between the plasma energy multiplication and the confinement parameter n tausub(E) of driven tokamak plasmas is added for reference. The conclusions summarize the results which could be obtained within the framework of energy balances, cost estimates and their parametric sensitivities. This is supplemented by listing those issues which lie beyond this scope but have to be taken into account when assessments of fusion-fission systems are made. (orig.)
Improved Calculation of Thermal Fission Energy
Ma, X. B.; Zhong, W. L.; Wang, L. Z.; Y. X. Chen; Cao, J
2012-01-01
Thermal fission energy is one of the basic parameters needed in the calculation of antineutrino flux for reactor neutrino experiments. It is useful to improve the precision of the thermal fission energy calculation for current and future reactor neutrino experiments, which are aimed at more precise determination of neutrino oscillation parameters. In this article, we give new values for thermal fission energies of some common thermal reactor fuel isotopes, with improvements on three aspects. ...
Laser solenoid fusion--fission design
International Nuclear Information System (INIS)
The dependence of breeding performance on system engineering parameters is examined for laser solenoid fusion-fission reactors. Reactor performance is found to be relatively insensitive to most of the engineering parameters, and compact designs can be built based on reasonable technologies. Point designs are described for the prototype series of reactors (mid-term technologies) and for second generation systems (advanced technologies). It is concluded that the laser solenoid has a good probability of timely application to fuel breeding needs
Research on stellarator-mirror fission-fusion hybrid
Moiseenko, V. E.; Kotenko, V. G.; Chernitskiy, S. V.; Nemov, V. V.; Ågren, O.; Noack, K.; Kalyuzhnyi, V. N.; Hagnestål, A.; Källne, J.; Voitsenya, V. S.; Garkusha, I. E.
2014-09-01
The development of a stellarator-mirror fission-fusion hybrid concept is reviewed. The hybrid comprises of a fusion neutron source and a powerful sub-critical fast fission reactor core. The aim is the transmutation of spent nuclear fuel and safe fission energy production. In its fusion part, neutrons are generated in deuterium-tritium (D-T) plasma, confined magnetically in a stellarator-type system with an embedded magnetic mirror. Based on kinetic calculations, the energy balance for such a system is analyzed. Neutron calculations have been performed with the MCNPX code, and the principal design of the reactor part is developed. Neutron outflux at different outer parts of the reactor is calculated. Numerical simulations have been performed on the structure of a magnetic field in a model of the stellarator-mirror device, and that is achieved by switching off one or two coils of toroidal field in the Uragan-2M torsatron. The calculations predict the existence of closed magnetic surfaces under certain conditions. The confinement of fast particles in such a magnetic trap is analyzed.
Fission thrust sail as booster for high Δv fusion based propulsion
Ceyssens, Frederik; Wouters, Kristof; Driesen, Maarten
2015-12-01
The fission thrust sail as booster for nuclear fusion-based rocket propulsion for future starships is introduced and studied. First order calculations are used together with Monte Carlo simulations to assess system performance. If a D-D fusion rocket such as e.g. considered in Project Icarus has relatively low efficiency (~30%) in converting fusion fuel to a directed exhaust, adding a fission sail is shown to be beneficial for the obtainable delta-v. In addition, this type of fission-fusion hybrid propulsion has the potential to improve acceleration and act as a micrometeorite shield.
Fission Thrust sail as booster for high {\\Delta}v fusion based propulsion
Ceyssens, Frederik; Driesen, Maarten
2014-01-01
The fission thrust sail as booster for nuclear fusion-based rocket propulsion for future starships is studied. Some required aspects of these systems such as neutron moderation and sail regeneration are discussed. First order calculations are used together with Monte Carlo simulations to assess system performance. When the fusion rocket has relatively low efficiency (~30%) in converting fusion fuel to a directed exhaust, adding a fission sail is shown to be beneficial for obtainable delta-v. Also, this type of fission-fusion hybrid interstellar propulsion has the potential to improve acceleration. Other advantages are discussed as well.
Fission Thrust sail as booster for high {\\Delta}v fusion based propulsion
Ceyssens, Frederik; Wouters, Kristof; Driesen, Maarten
2014-01-01
The fission thrust sail as booster for nuclear fusion-based rocket propulsion for future starships is studied. Some required aspects of these systems such as neutron moderation and sail regeneration are discussed. First order calculations are used together with Monte Carlo simulations to assess system performance. When the fusion rocket has relatively low efficiency (~30%) in converting fusion fuel to a directed exhaust, adding a fission sail is shown to be beneficial for obtainable delta-v. ...
Fusion-Fission hybrid reactors and nonproliferation
International Nuclear Information System (INIS)
New options for the development of the nuclear energy economy which might become available by a successful development of fusion-breeders or fusion-fission hybrid power reactors, identified and their nonproliferative attributes are discussed. The more promising proliferation-resistance ettributes identified include: (1) Justification for a significant delay in the initiation of fuel processing, (2) Denaturing the plutonium with 238Pu before its use in power reactors of any kind, and (3) Making practical the development of denatured uranium fuel cycles and, in particular, denaturing the uranium with 232U. Fuel resource utilization, time-table and economic considerations associated with the use of fusion-breeders are also discussed. It is concluded that hybrid reactors may enable developing a nuclear energy economy which is more proliferation resistant than possible otherwise, whileat the same time, assuring high utilization of t he uranium and thorium resources in an economically acceptable way. (author)
A Fusion-Fission Reactor Concept based on Viable Technologies
International Nuclear Information System (INIS)
Full text: The world needs a great deal of carbon free energy for civilization to continue. Nuclear power is attractive for helping cut carbon emissions and reducing imports of fossil fuel. It is commonly realized that it needs hard work before pure fusion energy could be commercially and economically utilized. Some countries are speeding up the development of their fission industry. In China, the government has decided to develop nuclear power with a mid-term target of ∼40 GWe in 2020. If only PWR is used to meet the huge nuclear capacity requirement, there may be a shortage of fissile uranium and an increase of long-lived nuclear wastes. Therefore, any activity to solve the problems has been welcome. A lot of research activities had been done to evaluate the possibility of the hybrid systems in the world, however, most of them were based on advanced fusion and fission technologies. In this contribution, three types of fusion-fission hybrid reactor concepts, i.e. the energy multiplier named FDS-EM, the fuel breeder named FDS-FB, waste transmuter named FDS-WT, have been proposed for the re-examination of feasibility, capability and safety and environmental potential of fission-fusion hybrid systems. Then based on the re-evaluation activity, a multi-functional fusion-fission reactor concept named FDS-MF simultaneously for nuclear waste transmutation, fissile fuel breeding and thermal energy production based on viable technologies i.e. available or limitedly extrapolated nuclear, processing and fusion technologies is proposed. The tokamak can be designed based on relatively easy-achieved plasma parameters extrapolated from the successful operation of the Experimental Advanced Superconducting Tokamak (EAST) in China and other tokamaks in the world, and the subcritical blanket can be designed based on the well-developed technology of PWR. The design and optimization of fusion plasma core parameters, fission blanket and fuel cycle have been presented. And the
Calculation code of the fission products activity
International Nuclear Information System (INIS)
The document describes the two codes for the calculation of the fission products activity. The ''Pepin le bref'' code gives the exact value of the beta and gamma activities of completely known fission products. The code ''Plus Pepin'' introduces the beta and gamma activities whose properties are partially known. (A.L.B.)
Fission cross section calculations for Pa isotopes
International Nuclear Information System (INIS)
Based on the recently measured cross-section values for the neutron-induced fission of 231Pa and our experience gained with other isotopes, new self consistent neutron cross section calculations for n+231Pa have been performed up to 30 MeV. The results are quite different to the existing evaluations, especially above the first chance fission threshold. (authors)
Tritium chemistry in fission and fusion reactors
International Nuclear Information System (INIS)
We are interested in the behaviour of tritium inside the solids where it is generated both in the case of fission nuclear reactor fuel elements, and in that of blankets of future fusion reactor. In the first case it is desirable to be able to predict whether tritium will be found in the hulls or in the uranium oxide, and under what chemical form, in order to take appropriate steps for it's removal in reprocessing plants. In fusion reactors breeding large amounts of tritium and burning it in the plasma should be accomplished in as short a cycle as possible in order to limit inventories that are associated with huge activities. Mastering the chemistry of every step is therefore essential. Amounts generated are not of the same order of magnitude in the two cases studied. Ternary fissions produce about 66 1013Bq (18 000 Ci) per year of tritium in a 1000 MWe fission generator, i.e., about 1.8 1010Bq (0.5 Ci) per day per ton of fuel
Fusion and fission of atomic clusters: recent advances
DEFF Research Database (Denmark)
Obolensky, Oleg I.; Solov'yov, Ilia; Solov'yov, Andrey V.;
2005-01-01
We review recent advances made by our group in finding optimized geometries of atomic clusters as well as in description of fission of charged small metal clusters. We base our approach to these problems on analysis of multidimensional potential energy surface. For the fusion process we have...... developed an effective scheme of adding new atoms to stable cluster geometries of larger clusters in an efficient way. We apply this algorithm to finding geometries of metal and noble gas clusters. For the fission process the analysis of the potential energy landscape calculated on the ab initio level...... of theory allowed us to obtain very detailed information on energetics and pathways of the different fission channels for the Na^2+_10 clusters....
Utilization of fission reactors for fusion engineering testing
Energy Technology Data Exchange (ETDEWEB)
Deis, G.A.; Miller, L.G.
1985-02-08
Fission reactors can be used to conduct some of the fusion nuclear engineering tests identified in the FINESSE study. To further define the advantages and disadvantages of fission testing, the technical and programmatic constraints on this type of testing are discussed here. This paper presents and discusses eight key issues affecting fission utilization. Quantitative comparisons with projected fusion operation are made to determine the technical assets and limitations of fission testing. Capabilities of existing fission reactors are summarized and compared with technical needs. Conclusions are then presented on the areas where fission testing can be most useful.
Fusion-fission energy systems evaluation
International Nuclear Information System (INIS)
This report serves as the basis for comparing the fusion-fission (hybrid) energy system concept with other advanced technology fissile fuel breeding concepts evaluated in the Nonproliferation Alternative Systems Assessment Program (NASAP). As such, much of the information and data provided herein is in a form that meets the NASAP data requirements. Since the hybrid concept has not been studied as extensively as many of the other fission concepts being examined in NASAP, the provided data and information are sparse relative to these more developed concepts. Nevertheless, this report is intended to provide a perspective on hybrids and to summarize the findings of the rather limited analyses made to date on this concept
Fusion-fission energy systems evaluation
Energy Technology Data Exchange (ETDEWEB)
Teofilo, V.L.; Aase, D.T.; Bickford, W.E.
1980-01-01
This report serves as the basis for comparing the fusion-fission (hybrid) energy system concept with other advanced technology fissile fuel breeding concepts evaluated in the Nonproliferation Alternative Systems Assessment Program (NASAP). As such, much of the information and data provided herein is in a form that meets the NASAP data requirements. Since the hybrid concept has not been studied as extensively as many of the other fission concepts being examined in NASAP, the provided data and information are sparse relative to these more developed concepts. Nevertheless, this report is intended to provide a perspective on hybrids and to summarize the findings of the rather limited analyses made to date on this concept.
Calculated medium energy fission cross sections
International Nuclear Information System (INIS)
An analysis has been made of medium-energy nucleon induced fission of 238U and 237Np using detailed models of fission, based upon the Bohr-Wheeler formalism. Two principal motivations were associated with these calculations. The first was determination of barrier parameters for proton-rich uranium and neptunium isotopes normally not accessible in lower energy reactions. The second was examination of the consistency between (p,f) experimental data versus new (n,f) data that has recently become available. Additionally, preliminary investigations were also made concerning the effect of fission dynamics on calculated fission cross sections at higher energies where neutron emission times may be significantly less than those associated with fission
A revised calculational model for fission
International Nuclear Information System (INIS)
A semi-empirical parametrization has been developed to calculate the fission contribution to evaporative de-excitation of nuclei with a very wide range of charge, mass and excitation-energy and also the nuclear states of the scission products. The calculational model reproduces measured values (cross-sections, mass distributions, etc.) for a wide range of fissioning systems: Nuclei from Ta to Cf, interactions involving nucleons up to medium energy and light ions. (author)
A revised calculational model for fission
Energy Technology Data Exchange (ETDEWEB)
Atchison, F.
1998-09-01
A semi-empirical parametrization has been developed to calculate the fission contribution to evaporative de-excitation of nuclei with a very wide range of charge, mass and excitation-energy and also the nuclear states of the scission products. The calculational model reproduces measured values (cross-sections, mass distributions, etc.) for a wide range of fissioning systems: Nuclei from Ta to Cf, interactions involving nucleons up to medium energy and light ions. (author)
Excitation Functions of Fusion and Fission for 32S+170Er at Energies Near and Below Coulomb Barrier
Institute of Scientific and Technical Information of China (English)
BAO; Peng-fei; LIN; Cheng-jian; YANG; Feng; JIA; Hui-ming; XU; Xin-xing; YANG; Lei; SUN; Li-jie; MA; Nan-ru; ZHANG; Huan-qiao; LIU; Zu-hua
2013-01-01
Excitation functions of fusion evaporation residue(ER)and fission for 32S+170Er system at near barrier energy region were measured,respectively.With the comparison to the calculations of coupledchannels effects,it is accessible to investigate the impacts on the fusion and fission processes of target deformation and the dependence on the entrance-channel.The experiment was performed at Beijing HI-13 Tandem Accelerator.Fission and fusion evaporation
A Fission-Fusion Origin for Life
Norris, V.; Raine, D. J.
1998-10-01
To develop a comprehensive `cells-first' approach to the origin of life, we propose that protocells form spontaneously and that the fission and fusion of these protocells drives the dynamics of their evolution. The fitness criterion for this evolution is taken to be the the stability (conservation) of domains in the protocellular membrane as determined by non-covalent molecular associations between the amphiphiles of the membrane and a subset of the macromolecules in the protocell. In the presence of a source of free energy the macromolecular content of the protocell (co-)evolves as the result of (domain-dependent) membrane-catalysed polymerisation of the prebiotic constituents delivered to the protocell by fusion. The metabolism of the cell therefore (co-)evolves on a rugged fitness landscape. We indicate how domain evolution with the same fitness criterion can potentially give rise to coding. Membrane domains may therefore provide the link between protocells and the RNA/DNA-world.
Analytic description of the fusion and fission processes through compact quasi-molecular shapes
International Nuclear Information System (INIS)
Recent studies have shown that the characteristics of the entrance and exit channels through compact quasi-molecular shapes are compatible with the experimental data on fusion, fission and cluster radioactivity when the deformation energy is determined within a generalized liquid drop model. Analytic expressions allowing to calculate rapidly the main characteristics of this deformation path through necked shapes with quasi-spherical ends are presented now; namely formulas for the fusion and fission barrier heights, the fusion barrier radius, the symmetric fission barriers and the proximity energy. (author)
Characterization of the fusion-fission process in light nuclear systems
International Nuclear Information System (INIS)
Fusion cross sections measurements of highly damped processes and elastic scattering were performed for the 16,17,18 O + 10,11 B and 19 F + 9 Be, in the incident energy interval 22 ≤ ELAB ≤ 64 MeV. Evidences are presented that highly damped binary processes observed in these systems are originated from a fusion-fission process rather than a dinuclear ''orbiting'' mechanism. The relative importance of the fusion-fission process in these very light systems is demonstrated both by the experimental results, which indicate a statistically balanced compound nucleus fission process occurrence, and theoretical calculations. (L.C.J.A.)
Autocatalytic fission-fusion microexplosions for nuclear pulse propulsion
Winterberg, F.
2000-12-01
Autocatalytic fission-fusion microexplosions, mutually amplifying fission and fusion reactions, are proposed for propulsion. Autocatalytic fission-fusion microexplosions can be realized by imploding a shell of uranium 235 (or plutonium) onto a magnetized deuterium-tritium (DT) plasma. After having reached a high temperature, the DT plasma releases fusion neutrons making fission reactions in the fissile shell increasing the implosion velocity which in turn increases the fusion reaction rate until full ignition of the DT plasma. To implode the fissile shell a small amount of high explosive and to magnetize the DT plasma a small auxiliary electric discharge are required. In comparison to nuclear bomb pulse propulsion, the energy released per pulse is much smaller and the efficiency higher. And in comparison to laser- or particle-beam-ignited fusion microexplosions, there is no need for a massive fusion ignition driver.
Trajectory Calculations in Light-Particle Fission
International Nuclear Information System (INIS)
Trajectory calculations based on a three-point-charge model were carried out for fission accompanied by 1H, 2H, 3H, 4He, 6He, 3He emission. The calculations were carried out with the intent of obtaining for each of these modes of fission the initial conditions which best fit the experimental results. The results indicate that both the initial distances between the fission fragments at scission and the initial kinetic energies of the particles tend to decrease as the mass of the light particle increases. In addition it was found that the experimental results could be better fitted by assuming that the particles are emitted off the axis connecting both fission fragments rather than on this axis. (author)
Genetically Controlled Fusion, Exocytosis and Fission of Artificial Vesicles
DEFF Research Database (Denmark)
Bönzli, Eva; Hadorn, Maik; De Lucrezia, Davide; Girke Jørgensen, Mikkel; Hotz, Peter Eggenberger; Hanczyc, Martin; Yomo, Tetsuya
special class of viral proteins, termed fusogenic peptides, were added to the external medium. In the present work, we intend to develop genetically controlled fusion, fission and exocytosis of vesicles by the synthesis of peptides within vesicles. First, we enclosed synthesized peptides in vesicles to...... induce in a next step fusion of adjacent vesicles, fission and exocytosis of nested vesicles. Second, we will replace the peptides by an enclosed cell-free expression system to internally synthesize fusion peptides. To control the gene expression, different mechanisms are available, e.g. addition of...... fusion, fission and exocytosis....
Fusion – fission dynamics: fragment mass distribution studies
Bhattacharya S; Chaudhuri A.; Ghosh T. K.; Banerjee K; Bhattacharya C.; Kundu S.; Mukherjee G; Rana T. K.; Roy P; Pandey R; Bhattacharya P
2015-01-01
Using the major accelerator facilities available in India, detailed experimental studies have been made to understand the mechanism of quasi-fission and role of nuclear shell effect in heavy nuclei. Fission fragment mass distribution has been used as the probe to explore the role of entrance channel effects on fusion-fission and quasifission dynamics. Fission fragment mass distribution has also been demonstrated to be useful to identify the phenomenon of ‘washing out’ of nuclear shell effect ...
Derivation of Energy Generated by Nuclear Fission-Fusion Reaction
Kayano, Hideo; Teshigawara, Makoto; Konashi, Kenji; Yamamoto, Takuya
1994-01-01
In the solids which contain fissionable elements and deuterium, it is expected that the energy generated by nuclear fission contributes to the promotion of the D-D nuclear fusion in the solids. When nuclear fission occurs by neutrons in the solid, the fissionable elements divide into two fission product nuclei having the energy of 100MeV, respectively. It is expected that the hige energy fission products promote rapidly nuclear fision reaction by knocking out the D atoms in the solids and by ...
Fusion-fission dynamics and synthesis of the superheavy elements
International Nuclear Information System (INIS)
Experiments of fusion-fission reactions clarify that the life time of nuclear fission is much longer than that expected from Bohr-Wheeler formula from the measurements of multiplicities of neutrons, gamma rays etc. emitted prior scission, and thereby appear to require a dynamical treatment of the process. Following the pioneering work by Kramers with the dissipation- fluctuation dynamics, the fissioning degree of freedom is described with the viewpoint of Brownian motion under incessant interactions with the heat bath particles, i.e., with nucleons in thermal equilibrium, in the present case. In the dynamical description the fission width is no more constant in time, but has a transient feature, as well as the reduction factor, the so-called Kramers factor. Both result in a longer life time, consistent with anomalous multiplicities measured. In the fusion process, Coulomb barriers play a crucial role in lighter heavy ion systems, but in very heavy systems it is known that there exists a hindrance in fusion. That is, the Coulomb barrier is not enough for determination of fusion probability, but an extra-energy above the barrier height is required for the system to fuse. This is understood by the properties of the Liquid Drop Model. After overcoming the Coulomb barrier, the ions touch with each other. But the united system, i.e., the pear-shaped configuration is located outside of the conditional saddle point or of the ridgeline. Therefore, in order to form the spherical compound nucleus, the system has to overcome one more barrier. Naturally, in such a situation, the kinetic energy carried in by the incident projectile has been more or less dissipated, i.e., the composite system is heated up. Thus, the shape evolution toward the spherical shape or toward the re-separation can be considered as a Brownian motion with the heat bath inside. The present author et al. have proposed the two-step model for fusion of massive heavy-ion systems where the fusion probability is
Structural materials for fission & fusion energy
Directory of Open Access Journals (Sweden)
Steven J. Zinkle
2009-11-01
Full Text Available Structural materials represent the key for containment of nuclear fuel and fission products as well as reliable and thermodynamically efficient production of electrical energy from nuclear reactors. Similarly, high-performance structural materials will be critical for the future success of proposed fusion energy reactors, which will subject the structures to unprecedented fluxes of high-energy neutrons along with intense thermomechanical stresses. Advanced materials can enable improved reactor performance via increased safety margins and design flexibility, in particular by providing increased strength, thermal creep resistance and superior corrosion and neutron radiation damage resistance. In many cases, a key strategy for designing high-performance radiation-resistant materials is based on the introduction of a high, uniform density of nanoscale particles that simultaneously provide good high temperature strength and neutron radiation damage resistance.
Fusion and fission of fluid amphiphilic bilayers.
Gotter, Martin; Strey, Reinhard; Olsson, Ulf; Wennerström, Håkan
2005-01-01
The system water-oil (n-decane)-nonionic surfactant (C12E5) forms bilayer phases in a large concentration region, but, for a given oil-to-surfactant ratio, only in a narrow temperature range. In addition to the anisotropic lamellar phase (Lalpha) there is also, at slightly higher temperature, a sponge or L3-phase where the bilayers build up an isotropic structure extending macroscopically in three dimensions. In this phase the bilayer mid-surface has a mean curvature close to zero and a negative Euler characteristic. In this paper we study how the bilayers in the lamellar and the sponge phase respond dynamically to sudden temperature changes. The monolayer spontaneous curvature depends sensitively on temperature and a change of temperature thus provides a driving force for a change in bilayer topology. The equilibration therefore involves kinetic steps of fusion/fission of bilayers. Such dynamic processes have previously been monitored by temperature jump experiments using light scattering in the sponge phase. These experiments revealed an extraordinarily strong dependence of the relaxation time on the bilayer volume fraction phi. At phi magnetic resonance (2H-NMR) appear feasible. We here report on the first experiments concerned with the dynamics of the macroscopic phase transition sponge-lamellae by 2H-NMR. We find that the sponge-to-lamellae transition occurs through a nucleation process followed by domain growth involving bilayer fission at domain boundaries. In contrast, the lamellae-to-sponge transformation apparently occurs through a succession of uncorrelated bilayer fusion events. PMID:15715316
Microscopic Calculations of 240Pu Fission
Energy Technology Data Exchange (ETDEWEB)
Younes, W; Gogny, D
2007-09-11
Hartree-Fock-Bogoliubov calculations have been performed with the Gogny finite-range effective interaction for {sup 240}Pu out to scission, using a new code developed at LLNL. A first set of calculations was performed with constrained quadrupole moment along the path of most probable fission, assuming axial symmetry but allowing for the spontaneous breaking of reflection symmetry of the nucleus. At a quadrupole moment of 345 b, the nucleus was found to spontaneously scission into two fragments. A second set of calculations, with all nuclear moments up to hexadecapole constrained, was performed to approach the scission configuration in a controlled manner. Calculated energies, moments, and representative plots of the total nuclear density are shown. The present calculations serve as a proof-of-principle, a blueprint, and starting-point solutions for a planned series of more comprehensive calculations to map out a large set of scission configurations, and the associated fission-fragment properties.
Static aspects of the fission and fusion of liquid 3He drops
International Nuclear Information System (INIS)
Using an effective 3He-3He interaction, the fission and fusion of 3He drops have been investigated from a static point of view. The calculations show that a fission barrier develops for these neutral systems, and that their saddle configurations are rather elongate. The transition from oblate to prolate shapes as a function of the angular momentum L, as well as critical values for fission and fusion are discussed for some selected cases. A kind of proximity potential can be extracted from the drop-drop interaction potentials. (author) 33 refs.; 9 figs
Effects of nuclear orientation on fusion and fission in the reaction using 238U target nucleus
Directory of Open Access Journals (Sweden)
Hirose K.
2010-03-01
Full Text Available Fission fragment mass distributions in the reaction of 30Si+238U were measured around the Coulomb barrier. At the above-barrier energies, the mass distribution showed a Gaussian shape. At the subbarrier energies, triple-humped distribution was observed, which consists of symmetric fission and asymmetric fission peaked at AL/AH ≈ 90/178. The asymmetric fission should be attributed to quasifission from the results of the measured evaporation residue (ER cross-sections for 30Si+238U. The cross-section for 263Sg at the abovebarrier energy agree with the statistical model calculation which assumes that the measured fission cross-section originates from fusion-fission, whereas the one for 264 Sg measured at the sub-barrier energy is smaller than the calculation, which suggests the presence of quasifission.
Pulsed Fission-Fusion (PuFF) Propulsion System Project
National Aeronautics and Space Administration — Fission-ignited fusion systems have been operational – in weapon form – since the 1950’s. Leveraging insights gained from the weapons physics...
Unified description of fission in fusion and spallation reactions
Mancusi, Davide; Charity, R. J.; Cugnon, Joseph
2010-01-01
We present a statistical-model description of fission, in the framework of compound-nucleus decay, which is found to simultaneously reproduce data from both heavy-ion-induced fusion reactions and proton-induced spallation reactions at around 1 GeV. For the spallation reactions, the initial compound-nucleus population is predicted by the Li\\`{e}ge Intranuclear Cascade Model. We are able to reproduce experimental fission probabilities and fission-fragment mass distributions in both reactions ty...
Calculations of fission rates for r-process nucleosynthesis
Panov, I. V.; Kolbe, E.; Pfeiffer, B.; Rauscher, T.; Kratz, K.-L.; Thielemann, F. -K.
2004-01-01
Fission plays an important role in the r-process which is responsible not only for the yields of transuranium isotopes, but may have a strong influence on the formation of the majority of heavy nuclei due to fission recycling. We present calculations of beta-delayed and neutron-induced fission rates, taking into account different fission barriers predictions and mass formulae. It is shown that an increase of fission barriers results naturally in a reduction of fission rates, but that neverthe...
Dynamics of morphological changes for mitochondrial fission and fusion
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Mitochondria experience continuous fusion and fission in a living cell, but their dynamics remains poorly quantified. Here a theoretical model was developed, upon a simplified population balance equation (PBE), to predict the morphological changes induced by mitochondrial fission and fusion. Assuming that both fission and fusion events are statistically independent, the survival probability of mitochondria staying in the fission or fusion state was formulated as an exponentially-decayed function with time, which depended on the time-dependent distribution of the mitochondrial volume and the fission and fusion rates. Parametric analysis was done for two typical volume distributions. One was Gamma distribution and the other was Gaussian distribution, derived from the measurements of volume distribution for individual mitochondria in a living cell and purified mitochondria in vitro. The predictions indicated that the survival probability strongly depended on morphological changes of individual mitochondria and was inversely correlated to the fission and fusion rates. This work provided a new insight into quantifying the mitochondrial dynamics via monitoring the evolution of the mitochondrial volume.
Probing fusion-fission dynamics in Bi203
Mukul, Ish; Nath, S.; Golda, K. S.; Jhingan, A.; Gehlot, J.; Prasad, E.; Kalkal, Sunil; Naik, M. B.; Banerjee, Tathagata; Varughese, T.; Sugathan, P.; Madhavan, N.; Pal, Santanu
2015-11-01
Background: Complete fusion between two massive nuclei after capture inside the potential barrier is inhibited by competing fission-like processes. The target-projectile composite system may reseparate after capture without proceeding towards formation of the compound nucleus (CN), which is equilibrated in all degrees of freedom. The nature of these non-CN fission (NCNF) processes and factors that affect them are not completely known yet. Purpose: The nuclear mass regions from where NCNF processes begin to manifest themselves are not clearly demarcated. This work aims to study the onset of NCNF, if any, in the mass region ˜200 . Methods: Fission fragment (FF) mass and angular distribution (MAD) and pre-scission and post-scission neutron multiplicities were measured for the reaction +W184F19 at a laboratory energy (Elab) range of 84-125 MeV. The measurements were carried out using two multiwire proportional counters (MWPC) to detect the FFs in coincidence and four neutron detectors to measure neutron time of flight (TOF). Statistical model (SM) calculation was performed. Results: No significant mass-angle correlation was observed in the MAD plots. Extracted mass ratio distributions were single-peaked and of Gaussian shape. Measured pre-scission neutron multiplicity values indicated dissipative nature of CN decay for this reaction. Conclusions: No clear signatures of NCNF were observed in the studied reaction, indicating that the target-projectile composite system predominantly proceeds towards formation of the CN after capture.
Perspective on the fusion-fission energy concept
International Nuclear Information System (INIS)
A concept which has potential for near-term application in the electric power sector of our energy economy is combining fusion and fission technology. The fusion-fission system, called a hybrid, is distinguished from its pure fusion counterpart by incorporation of fertile materials (uranium or thorium) in the blanket region of a fusion machine. The neutrons produced by the fusion process can be used to generate energy through fission events in the blanket or produce fuel for fission reactors through capture events in the fertile material. The performance requirements of the fusion component of hybrids is perceived as being less stringent than those for pure fusion electric power plants. The performance requirements for the fission component of hybrids is perceived as having been demonstrated or could be demonstrated with a modest investment of research and development funds. This paper presents our insights and observations of this concept in the context of why and where it might fit into the picture of meeting our future energy needs. A bibliography of hybrid research is given
Neutron emission as a probe of fusion-fission and quasi-fission dynamics
International Nuclear Information System (INIS)
Pre- and post scission neutron yeilds have been measured as a function of projectile mass, compound nucleus fissility, and fission mass-split and total kinetic energy (TKE) for 27 fusion-fission and quasi-fission reactions induced by beams of 16,18O, 40Ar and 64Ni. A new method of interpretation of experimental pre-scission neutron multiplicities ν-pre and mean kinetic energies εν allows the extraction of fission time scales with much less uncertainty than previously, all fusion-fission results being consistent with a dynamical time scale of (35±15) x 10-21s for symmetric fission. All reactions show that ν-pre falls quite rapidly with increasing mass-asymmetry; evidence is presented that for fusion-fission reactions this is partly due to a reduction of the dynamical fission time scale with mass-asymmetry. For quasi-fission, the data indicate that the pre-scission multiplicity and mean neutron kinetic energy are very sensitive to the final mass-asymmetry, but that the time scale is virtually independent of mass-asymmetry. It is concluded that for fusion-fission there is no dependence of ν-pre on TKE, whilst for 64Ni-induced quasi-fission reactions, a strong increase of ν-pre with decreasing TKE is observed, probably largely caused by neutron emission during the acceleration time of the fission fragments in these fast reactions. Interpretation of post-scission multiplicities in terms of fragment excitation energies leads to deduced time scales consistent with those determined from the pre-scission data. 54 refs., 17 tabs., 25 figs
Model of competition between complete fusion and quasi-fission in reactions with massive nuclei
International Nuclear Information System (INIS)
A model is proposed for the calculation of the competition between complete fusion and quasi-fission in a massive symmetric dinuclear system (DNS). The model is based on the DNS-approach to the analysis of complete nuclear fusion. The model has been to calculate the cross-sections of evaporation residues in the 100Mo+100Mo and 110Pd+110Pd reactions. ((orig.))
Model for fission-product calculations
International Nuclear Information System (INIS)
Many fission-product cross sections remain unmeasurable thus considerable reliance must be placed upon calculational interpolation and extrapolation from the few available measured cross sections. The vehicle, particularly for the lighter fission products, is the conventional optical-statistical model. The applied goals generally are: capture cross sections to 7 to 10% accuracies and inelastic-scattering cross sections to 25 to 50%. Comparisons of recent evaluations and experimental results indicate that these goals too often are far from being met, particularly in the area of inelastic scattering, and some of the evaluated fission-product cross sections are simply physically unreasonable. It is difficult to avoid the conclusion that the models employed in many of the evaluations are inappropriate and/or inappropriately used. In order to alleviate the above unfortunate situations, a regional optical-statistical (OM) model was sought with the goal of quantitative prediction of the cross sections of the lighter-mass (Z = 30-51) fission products. The first step toward that goal was the establishment of a reliable experimental data base consisting of energy-averaged neutron total and differential-scattering cross sections. The second step was the deduction of a regional model from the experimental data. It was assumed that a spherical OM is appropriate: a reasonable and practical assumption. The resulting OM then was verified against the measured data base. Finally, the physical character of the regional model is examined
Fusion – fission dynamics: fragment mass distribution studies
Directory of Open Access Journals (Sweden)
Bhattacharya S.
2015-01-01
Full Text Available Using the major accelerator facilities available in India, detailed experimental studies have been made to understand the mechanism of quasi-fission and role of nuclear shell effect in heavy nuclei. Fission fragment mass distribution has been used as the probe to explore the role of entrance channel effects on fusion-fission and quasifission dynamics. Fission fragment mass distribution has also been demonstrated to be useful to identify the phenomenon of ‘washing out’ of nuclear shell effect with excitation energy.
Fission-suppressed hybrid reactor: the fusion breeder
International Nuclear Information System (INIS)
Results of a conceptual design study of a 233U-producing fusion breeder are presented. The majority of the study was devoted to conceptual design and evaluation of a fission-suppressed blanket and to fuel cycle issues such as fuel reprocessing, fuel handling, and fuel management. Studies in the areas of fusion engineering, reactor safety, and economics were also performed
Fission-suppressed hybrid reactor: the fusion breeder
Energy Technology Data Exchange (ETDEWEB)
Moir, R.W.; Lee, J.D.; Coops, M.S.
1982-12-01
Results of a conceptual design study of a /sup 233/U-producing fusion breeder are presented. The majority of the study was devoted to conceptual design and evaluation of a fission-suppressed blanket and to fuel cycle issues such as fuel reprocessing, fuel handling, and fuel management. Studies in the areas of fusion engineering, reactor safety, and economics were also performed.
Fusion materials irradiations at MaRIE's fission fusion facility
Energy Technology Data Exchange (ETDEWEB)
Pitcher, Eric J [Los Alamos National Laboratory
2010-10-06
Los Alamos National Laboratory's proposed signature facility, MaRIE, will provide scientists and engineers with new capabilities for modeling, synthesizing, examining, and testing materials of the future that will enhance the USA's energy security and national security. In the area of fusion power, the development of new structural alloys with better tolerance to the harsh radiation environments expected in fusion reactors will lead to improved safety and lower operating costs. The Fission and Fusion Materials Facility (F{sup 3}), one of three pillars of the proposed MaRIE facility, will offer researchers unprecedented access to a neutron radiation environment so that the effects of radiation damage on materials can be measured in-situ, during irradiation. The calculated radiation damage conditions within the F{sup 3} match, in many respects, that of a fusion reactor first wall, making it well suited for testing fusion materials. Here we report in particular on two important characteristics of the radiation environment with relevancy to radiation damage: the primary knock-on atom spectrum and the impact of the pulse structure of the proton beam on temporal characteristics of the atomic displacement rate. With respect to both of these, analyses show the F{sup 3} has conditions that are consistent with those of a steady-state fusion reactor first wall.
Study on Fission Blanket Fuel Cycling of a Fusion-Fission Hybrid Energy Generation System
International Nuclear Information System (INIS)
Full text: Direct application of ITER-scale tokamak as a neutron driver in a subcritical fusion-fission hybrid reactor to generate electric power is of great potential in predictable future. This paper reports a primary study on neutronic and fuel cycle behaviors of a fission blanket for a new type of fusion-driven system (FDS), namely a subcritical fusion-fission hybrid reactor for electric power generation aiming at energy generation fueled with natural or depleted uranium. Using COUPLE2 developed at INET of Tsinghua University by coupling the MCNP code with the ORIGEN code to study the neutronic behavior and the refueling scheme, this paper focuses on refueling scheme of the fissionable fuel while keeping some important parameters such as tritium breeding ratio (TBR) and energy gain. Different fission fuels, coolants and their volumetric ratios arranged in the fission blanket satisfy the requirements for power generation. The results show that soft neutron spectrum with optimized fuel to moderator ratio can yield an energy amplifying factor of M> 20 while maintaining the TBR > 1.1 and the CR > 1 (the conversion ratio of fissile materials) in a reasonably long refueling cycle. Using an in-site fuel recycle plant, it will be an attractive way to realize the goal of burning 238U with such a new type of fusion-fission hybrid reactor system to generate electric power. (author)
Energy Technology Data Exchange (ETDEWEB)
Kramer, Kevin James [Univ. of California, Berkeley, CA (United States)
2010-04-08
This study investigates the neutronics design aspects of a hybrid fusion-fission energy system called the Laser Fusion-Fission Hybrid (LFFH). A LFFH combines current Laser Inertial Confinement fusion technology with that of advanced fission reactor technology to produce a system that eliminates many of the negative aspects of pure fusion or pure fission systems. When examining the LFFH energy mission, a significant portion of the United States and world energy production could be supplied by LFFH plants. The LFFH engine described utilizes a central fusion chamber surrounded by multiple layers of multiplying and moderating media. These layers, or blankets, include coolant plenums, a beryllium (Be) multiplier layer, a fertile fission blanket and a graphite-pebble reflector. Each layer is separated by perforated oxide dispersion strengthened (ODS) ferritic steel walls. The central fusion chamber is surrounded by an ODS ferritic steel first wall. The first wall is coated with 250-500 μm of tungsten to mitigate x-ray damage. The first wall is cooled by Li_{17}Pb_{83 } eutectic, chosen for its neutron multiplication and good heat transfer properties. The Li_{17}Pb_{83} flows in a jacket around the first wall to an extraction plenum. The main coolant injection plenum is immediately behind the Li_{17}Pb_{83}, separated from the Li_{17}Pb_{83} by a solid ODS wall. This main system coolant is the molten salt flibe (2LiF-BeF_{2}), chosen for beneficial neutronics and heat transfer properties. The use of flibe enables both fusion fuel production (tritium) and neutron moderation and multiplication for the fission blanket. A Be pebble (1 cm diameter) multiplier layer surrounds the coolant injection plenum and the coolant flows radially through perforated walls across the bed. Outside the Be layer, a fission fuel layer comprised of depleted uranium contained in Tristructural-isotropic (TRISO) fuel particles
Energy Technology Data Exchange (ETDEWEB)
Kramer, K
2010-04-08
This study investigates the neutronics design aspects of a hybrid fusion-fission energy system called the Laser Fusion-Fission Hybrid (LFFH). A LFFH combines current Laser Inertial Confinement fusion technology with that of advanced fission reactor technology to produce a system that eliminates many of the negative aspects of pure fusion or pure fission systems. When examining the LFFH energy mission, a significant portion of the United States and world energy production could be supplied by LFFH plants. The LFFH engine described utilizes a central fusion chamber surrounded by multiple layers of multiplying and moderating media. These layers, or blankets, include coolant plenums, a beryllium (Be) multiplier layer, a fertile fission blanket and a graphite-pebble reflector. Each layer is separated by perforated oxide dispersion strengthened (ODS) ferritic steel walls. The central fusion chamber is surrounded by an ODS ferritic steel first wall. The first wall is coated with 250-500 {micro}m of tungsten to mitigate x-ray damage. The first wall is cooled by Li{sub 17}Pb{sub 83} eutectic, chosen for its neutron multiplication and good heat transfer properties. The {sub 17}Pb{sub 83} flows in a jacket around the first wall to an extraction plenum. The main coolant injection plenum is immediately behind the Li{sub 17}Pb{sub 83}, separated from the Li{sub 17}Pb{sub 83} by a solid ODS wall. This main system coolant is the molten salt flibe (2LiF-BeF{sub 2}), chosen for beneficial neutronics and heat transfer properties. The use of flibe enables both fusion fuel production (tritium) and neutron moderation and multiplication for the fission blanket. A Be pebble (1 cm diameter) multiplier layer surrounds the coolant injection plenum and the coolant flows radially through perforated walls across the bed. Outside the Be layer, a fission fuel layer comprised of depleted uranium contained in Tristructural-isotropic (TRISO) fuel particles having a packing fraction of 20% in 2 cm
Calculations of fission rates for r-process nucleosynthesis
Panov, I V; Pfeiffer, B; Rauscher, T; Kratz, K L; Thielemann, F K
2005-01-01
Fission plays an important role in the r-process which is responsible not only for the yields of transuranium isotopes, but may have a strong influence on the formation of the majority of heavy nuclei due to fission recycling. We present calculations of beta-delayed and neutron-induced fission rates, taking into account different fission barriers predictions and mass formulae. It is shown that an increase of fission barriers results naturally in a reduction of fission rates, but that nevertheless fission leads to the termination of the r-process. Furthermore, it is discussed that the probability of triple fission could be high for $A>260$ and have an effect on the formation of the abundances of heavy nuclei. Fission after beta-delayed neutron emission is discussed as well as different aspects of the influence of fission upon r-process calculations.
International Nuclear Information System (INIS)
To check the data of carbon material reflecting neutrons, the distribution of 238U fission reaction rates induced by D-T fusion neutrons reflected by carbon material was measured by using the small depleted uranium fission chamber and the capturing detector. For comparison, 238U fission rates without carbon material was measured too. The combined standard uncertainty of 238U fission reaction rate is 5.1%-6.4%. The measured results are consistent with the calculated ones with MCNP/4A code and ENDF/B-IV library data in the range of the error
Regulatory aspects of fusion power-lessons from fission plants
Natalizio, A.; Sood, S. K.; Brunnader, H.
1993-06-01
Experience from fission reactors has shown the regulatory process for licensing a nuclear facility to be legalistic, lengthy, unpredictable, and costly. This experience also indicates that much of the regulatory debate is focused on safety margins, that is, the smaller the safety margins the bigger the regulatory debate and the greater the amount of proof required to satisfy the regulator. Such experience suggests that caution and prudence guide the development of a regulatory regime for fusion reactors. Fusion has intrinsic safety and environmental advantages over fission, which should alleviate significantly, or even eliminate, the regulatory problems associated with fission. The absence of a criticality concern and the absence of fission products preclude a Chernobyl type accident from occurring in a fusion reactor. Although in a fusion reactor there are large inventories of radioactive products that can be mobilized, the total quantity is orders of magnitude smaller than in fission power reactors. The bulk of the radioactivity in a fusion reactor is either activation products in steel structures, or tritium fuel supplies safely stored in the form of a metal tritide in storage beds. The quantity of tritium that can be mobilized under accident conditions is much less than ten million curies. This compares very favorably with a fission product inventory greater than ten billion curies in a fission power reactor. Furthermore, in a fission reactor, all of the reactivity is contained in a steel vessel that is pressurized to about 150 atmospheres, whereas in a fusion reactor, the inventory of radioactive material is dispersed in different areas of the plant, such that it is improbable that a single event could give rise to the release of the entire inventory to the environment. These intrinsic features give fusion a significant safety and environmental advantage over fission. With such significant intrinsic safety advantages there is no a priori need to make fusion
Kramer, Kevin James
2010-01-01
This study investigates the neutronics design aspects of a hybrid fusion-fission energy system called the Laser Fusion-Fission Hybrid (LFFH). A LFFH combines current Laser Inertial Confinement fusion technology with that of advanced fission reactor technology to produce a system that eliminates many of the negative aspects of pure fusion or pure fission systems. When examining the LFFH energy mission, a significant portion of the United States and world energy production could be supplied by ...
Developing the Pulsed Fission-Fusion (PuFF) Engine
Adams, Robert B.; Cassibry, Jason; Bradley, David; Fabisinski, Leo; Statham, Geoffrey
2014-01-01
In September 2013 the NASA Innovative Advanced Concept (NIAC) organization awarded a phase I contract to the PuFF team. Our phase 1 proposal researched a pulsed fission-fusion propulsion system that compressed a target of deuterium (D) and tritium (T) as a mixture in a column, surrounded concentrically by Uranium. The target is surrounded by liquid lithium. A high power current would flow down the liquid lithium and the resulting Lorentz force would compress the column by roughly a factor of 10. The compressed column would reach criticality and a combination of fission and fusion reactions would occur. Our Phase I results, summarized herein, review our estimates of engine and vehicle performance, our work to date to model the fission-fusion reaction, and our initial efforts in experimental analysis.
Competition between fusion-fission and quasifission processes in the 32S+184W reaction
International Nuclear Information System (INIS)
The angular distributions of fission fragments for the 32S+184W reaction at center-of-mass energies of 118.8, 123.1, 127.3, 131.5, 135.8, 141.1, and 144.4 MeV are measured. The experimental fission excitation function is obtained. The anisotropy (Aexp) is found by extrapolating each fission fragment angular distribution. The measured fission cross sections of the 32S+182,184W reaction are decomposed into fusion-fission, quasifission, and fast-fission contributions by the dinuclear system model (DNS). The angular momentum distributions of the dinuclear system and compound nucleus calculated by the DNS model are used to reproduce the experimental capture and fusion excitation functions for both reactions and quantities K02, 2>, and Aexp, which characterize angular distributions of the fission products at the considered range of beam energy. The total evaporation residue excitation function for the 32S+184W reaction calculated in the framework of the advanced statistical model is close to the available experimental data only up to about Ec.m.≅160 MeV. The underestimation of the experimental data at high excitation energies Ec.m.>160 MeV is explained by the fact that the statistical model cannot reproduce the cross section of evaporation residues formed by the nonequilibrium mechanism, that is, without formation of the compound nucleus in the statistical equilibrium state.
Preliminary design of core plasma parameters for the fusion-fission hybrid reactor based on GDT
International Nuclear Information System (INIS)
Based on the recent experiment progress of Gas Dynamic Trap (GDT), a core plasma physics conceptual design for driving fission blanket was proposed. The 0-D physical model was built and the core plasma parameters with 50 MW fusion power were preliminarily designed. The reliability of the physical model and design was demonstrated by comparison between the calculation and the experiment results. (authors)
Hemi-fused structure mediates and controls fusion and fission in live cells.
Zhao, Wei-Dong; Hamid, Edaeni; Shin, Wonchul; Wen, Peter J; Krystofiak, Evan S; Villarreal, Seth A; Chiang, Hsueh-Cheng; Kachar, Bechara; Wu, Ling-Gang
2016-06-23
Membrane fusion and fission are vital for eukaryotic life. For three decades, it has been proposed that fusion is mediated by fusion between the proximal leaflets of two bilayers (hemi-fusion) to produce a hemi-fused structure, followed by fusion between the distal leaflets, whereas fission is via hemi-fission, which also produces a hemi-fused structure, followed by full fission. This hypothesis remained unsupported owing to the lack of observation of hemi-fusion or hemi-fission in live cells. A competing fusion hypothesis involving protein-lined pore formation has also been proposed. Here we report the observation of a hemi-fused Ω-shaped structure in live neuroendocrine chromaffin cells and pancreatic β-cells, visualized using confocal and super-resolution stimulated emission depletion microscopy. This structure is generated from fusion pore opening or closure (fission) at the plasma membrane. Unexpectedly, the transition to full fusion or fission is determined by competition between fusion and calcium/dynamin-dependent fission mechanisms, and is notably slow (seconds to tens of seconds) in a substantial fraction of the events. These results provide key missing evidence in support of the hemi-fusion and hemi-fission hypothesis in live cells, and reveal the hemi-fused intermediate as a key structure controlling fusion and fission, as fusion and fission mechanisms compete to determine the transition to fusion or fission. PMID:27309816
Dynamics in heavy ion fusion and fission
International Nuclear Information System (INIS)
Dynamical aspects of heavy ion fussion and fission, mainly the aspect of damping which is meant as the dissipation of kinetic energy and the aspect of the effective mass of the fission motion, are discussed. Two categories of evidence of damping effects are given. One relates to the damping of the fission motion for the ground state shape and for the isomeric more elongated shape. The other relates to the damping of the fission motion from the last barrier to the scission point. The dependence of the effective mass associated with the fission motion on the deormation of nucleus is shown. As the elongation of the nucleus increases the effective mass of the fission motion varies strongly from being about forty times greater than the reduced mass in the beta-vibrational state of the ground state shape to being equal to the reduced mass in the moment of scission. Damping effects are expected to be propartional to the difference between the effective mass and the reduced mass. It is concluded that the damping in fussion reactions is relatively weak for lighter products and quite strong for superheavy products like 236U or 252Cf. (S.B.)
Basics of Fusion-Fission Research Facility (FFRF) as a Fusion Neutron Source
International Nuclear Information System (INIS)
FFRF, standing for the Fusion-Fission Research Facility represents an option for the next step project of ASIPP (Hefei, China) aiming to a first fusion-fission multifunctional device (1). FFRF strongly relies on new, Lithium Wall Fusion plasma regimes, the development of which has already started in the US and China. With R/a=4/1m/m, Ipl=5 MA, Btor=4-6 T, PDT=50- 100 MW, Pfission=80-4000MW, 1 m thick blanket, FFRF has a unique fusion mission of a stationary fusion neutron source. Its pioneering mission of merging fusion and fission consists in accumulation of design, experimental, and operational data for future hybrid applications.
Fission-Fusion Neutron Source Progress Report July 31, 2009
Energy Technology Data Exchange (ETDEWEB)
Chapline, G; Daffin, F; Clarke, R
2010-02-19
In this report the authors describe progress in evaluating the feasibility of a novel concept for producing intense pulses of 14 MeV neutrons using the DT fusion reaction. In this new scheme the heating of the DT is accomplished using fission fragments rather than ion beams as in conventional magnet fusion schemes or lasers in ICF schemes. This has the great advantage that there is no need for any large auxiliary power source. The scheme does require large magnetic fields, but generating these fields, e.g. with superconducting magnets, requires only a modest power source. As a source of fission fragments they propose using a dusty reactor concept introduced some time ago by one of us (RC). The version of the dusty reactor that they propose using for our neutron source would operate as a thermal neutron reactor and use highly enriched uranium in the form of micron sized pellets of UC. Our scheme for using the fission fragments to produce intense pulses of 14 MeV neutrons is based on the fission fragment rocket idea. In the fission fragment rocket scheme it was contemplated that the fission fragments produced in a low density reactor core would then be guided out of the reactor by large magnetic fields. A simple version of this idea would be to use the fission fragments escaping from one side of a tandem magnet mirror to heat DT gas confined in the adjacent magnetic trap.
Reaction rates in blanket assemblies of a fusion-fission hybrid reactor
International Nuclear Information System (INIS)
To validate neutronics calculation for the blanket design of fusion-fission hybrid reactor, experiments for measuring reaction rates inside two simulating assemblies are performed. Two benchmark assemblies were developed for the neutronics experiments. A D-T fusion neutron source is placed at the center of the setup. One of them consists of three layers of depleted uranium shells and two layers of polyethylene shells, and these shells are arranged alternatively. The 238U capture reaction rates are measured using depleted uranium foils and an HPGe gamma spectrometer. The fission reaction rates are measured using a fission chamber coated with depleted uranium. The other assembly consists of depleted uranium and LiH shells. The tritium production rates are measured using the lithium glass scintillation detector which is placed in the LiH region of the assembly. The measured reaction rates are compared with the calculated ones predicted using MCNP code, and C/E values are obtained. (authors)
1D Burnup Calculation of Fusion-Fission Hybrid Energy Reactor%聚变-裂变混合能源堆一维计算模型燃耗分析
Institute of Scientific and Technical Information of China (English)
李茂生; 师学明; 伊炜伟
2012-01-01
Fusion-fission hybrid energy reactor is driven by Tokamak fusion source for energy production. Its subcritical zone uses the natural uranium as fuel and water as coolant. The neutron multiplication constant keff, energy multiplication factor M and tritium breeding ratio TBR of the ID hybrid energy reactor model were calculated by transport burnup code MCORGS. The neutron spectrum and nuclear density changing as a function of time show the characteristics of the hybrid energy reactors, which differs from the hybrid reactor for breed nuclear fuel and for spent fuel transmutation. The definition and results may be a reference to the other conceptual analysis.%聚变-裂变混合能源堆包括聚变中子源和以天然铀为燃料、水为冷却剂的次临界包层,主要目标是生产电力.利用输运燃耗耦合程序系统MCORGS计算了混合能源堆一维模型的燃耗,给出了中子有效增殖因数keff、能量放大倍数M、氚增殖比TBR等物理量随时间的变化.通过分析能谱和重要核素随燃耗时间的变化,说明混合能源堆与核燃料增殖、核废料嬗变混合堆的不同特点.本文给出的结果可作为混合堆中子输运、燃耗分析程序校验的参考数据,为混合堆概念研究提供了基础数据.
Mitochondrial Fusion, Fission and Autophagy as a Quality Control Axis: The Bioenergetic View
Twig, Gilad; Hyde, Brigham; Shirihai, Orian S.
2008-01-01
The mitochondrial life cycle consists of frequent fusion and fission events. Ample experimental and clinical data demonstrate that inhibition of either fusion or fission result in deterioration of mitochondrial bioenergetics. While fusion may benefit mitochondrial function by allowing the spreading of metabolites, protein and DNA throughout the network, the functional benefit of fission is not as intuitive. Remarkably, studies that track individual mitochondria through fusion and fission foun...
Nuclear structure in cold rearrangement processes in fission and fusion
International Nuclear Information System (INIS)
In fission and fusion of heavy nuclei large numbers of nucleons are rearranged at a scale of excitation energy very small compared to the binding energy of the nuclei. The energies involved are less than 40 MeV at nuclear temperatures below 1.5 MeV. The shapes of the configurations in the rearrangement of a binary system into a monosystem in fusion, or vice versa in fission, change their elongations by as much as 8 fm, the radius of the monosystem. The dynamics of the reactions macroscopically described by a potential energy surface, inertia parameters, dissipation, and a collision energy is strongly modified by the nuclear structure of the participating nuclei. Experiments showing nuclear structure effects in fusion and fission of the heaviest nuclei are reviewed. The reaction kinematics and the multitude of isotopes involved are investigated by detector techniques and by recoil spectrometers. The advancement of the latter allows to find very small reaction branches in the range of 10-5 to 10-10. The experiments reveal nuclear structure effects in all stages of the rearrangement processes. These are discussed pointing to analogies in fusion and fission on the microscopic scale, notwithstanding that both processes macroscopically are irreversible. Heavy clusters, as 132Sn, 208Pb, nuclei with closed shell configurations N=82,126, Z=50,82 survive in large parts of the nuclear rearrangement. They determine the asymmetry in the mass distribution of low energy fission, and they allow to synthesise superheavy elements, until now up to element 112. Experiments on the cold rearrangement in fission and fusion are presented. Here, in the range of excitation energies below 12 MeV the phenomena are observed most convincingly. (orig.)
Nuclear structure in cold rearrangement processes in fission and fusion
Energy Technology Data Exchange (ETDEWEB)
Armbruster, P.
1998-11-01
In fission and fusion of heavy nuclei large numbers of nucleons are rearranged at a scale of excitation energy very small compared to the binding energy of the nuclei. The energies involved are less than 40 MeV at nuclear temperatures below 1.5 MeV. The shapes of the configurations in the rearrangement of a binary system into a monosystem in fusion, or vice versa in fission, change their elongations by as much as 8 fm, the radius of the monosystem. The dynamics of the reactions macroscopically described by a potential energy surface, inertia parameters, dissipation, and a collision energy is strongly modified by the nuclear structure of the participating nuclei. Experiments showing nuclear structure effects in fusion and fission of the heaviest nuclei are reviewed. The reaction kinematics and the multitude of isotopes involved are investigated by detector techniques and by recoil spectrometers. The advancement of the latter allows to find very small reaction branches in the range of 10{sup -5} to 10{sup -10}. The experiments reveal nuclear structure effects in all stages of the rearrangement processes. These are discussed pointing to analogies in fusion and fission on the microscopic scale, notwithstanding that both processes macroscopically are irreversible. Heavy clusters, as 132Sn, 208Pb, nuclei with closed shell configurations N=82,126, Z=50,82 survive in large parts of the nuclear rearrangement. They determine the asymmetry in the mass distribution of low energy fission, and they allow to synthesise superheavy elements, until now up to element 112. Experiments on the cold rearrangement in fission and fusion are presented. Here, in the range of excitation energies below 12 MeV the phenomena are observed most convincingly. (orig.)
Transmutation of fission product 93 Zr by fusion neutron source
International Nuclear Information System (INIS)
The problem of 93 Zr accumulation and its transmutation is addressed. It is shown that neutron flux required for 93 Zr transmutation is unachievable in fission reactor. Therefore transmutation of 93 Zr in the fusion based facility is proposed. It is demonstrated that current ITER fusion reactor project can be sufficiently served as a transmuter to resolve the problem of 93 Zr accumulation within the time period of several decades
Feasibility study of a fission-suppressed tokamak fusion breeder
Energy Technology Data Exchange (ETDEWEB)
Moir, R.W.; Lee, J.D.; Neef, W.S.; Berwald, D.H.; Garner, J.K.; Whitley, R.H.; Ghoniem, N.; Wong, C.P.C.; Maya, I.; Schultz, K.R.
1984-12-01
The preliminary conceptual design of a tokamak fissile fuel producer is described. The blanket technology is based on the fission suppressed breeding concept where neutron multiplication occurs in a bed of 2 cm diameter beryllium pebbles which are cooled by helium at 50 atmospheres pressure. Uranium-233 is bred in thorium metal fuel elements which are in the form of snap rings attached to each beryllium pebble. Tritium is bred in lithium bearing material contained in tubes immersed in the pebble bed and is recovered by a purge flow of helium. The neutron wall load is 3 MW/m/sup 2/ and the blanket material is ferritic steel. The net fissile breeding ratio is 0.54 +- 30% per fusion reaction. This results in the production of 4900 kg of /sup 233/U per year from 3000 MW of fusion power. This quantity of fuel will provide makeup fuel for about 12 LWRs of equal thermal power or about 18 1 GW/sub e/ LWRs. The calculated cost of the produced uranium-233 is between $23/g and $53/g or equivalent to $10/kg to $90/kg of U/sub 3/O/sub 8/ depending on government financing or utility financing assumptions. Additional topics discussed in the report include the tokamak operating mode (both steady state and long pulse considered), the design and breeding implications of using a poloidal divertor for impurity control, reactor safety, the choice of a tritium breeder, and fuel management.
Feasibility study of a fission-suppressed tokamak fusion breeder
International Nuclear Information System (INIS)
The preliminary conceptual design of a tokamak fissile fuel producer is described. The blanket technology is based on the fission suppressed breeding concept where neutron multiplication occurs in a bed of 2 cm diameter beryllium pebbles which are cooled by helium at 50 atmospheres pressure. Uranium-233 is bred in thorium metal fuel elements which are in the form of snap rings attached to each beryllium pebble. Tritium is bred in lithium bearing material contained in tubes immersed in the pebble bed and is recovered by a purge flow of helium. The neutron wall load is 3 MW/m2 and the blanket material is ferritic steel. The net fissile breeding ratio is 0.54 +- 30% per fusion reaction. This results in the production of 4900 kg of 233U per year from 3000 MW of fusion power. This quantity of fuel will provide makeup fuel for about 12 LWRs of equal thermal power or about 18 1 GW/sub e/ LWRs. The calculated cost of the produced uranium-233 is between $23/g and $53/g or equivalent to $10/kg to $90/kg of U3O8 depending on government financing or utility financing assumptions. Additional topics discussed in the report include the tokamak operating mode (both steady state and long pulse considered), the design and breeding implications of using a poloidal divertor for impurity control, reactor safety, the choice of a tritium breeder, and fuel management
Fission-reactor experiments for fusion-materials research
International Nuclear Information System (INIS)
The US Fusion Materials Program makes extensive use of fission reactors to study the effects of simulated fusion environments on materials and to develop improved alloys for fusion reactor service. The fast reactor, EBR-II, and the mixed spectrum reactors, HFIR and ORR, are all used in the fusion program. The HFIR and ORR produce helium from transmutations of nickel in a two-step thermal neutron absorption reaction beginning with 58Ni, and the fast neutrons in these reactors produce atomic displacements. The simultaneous effects of these phenomena produce damage similar to the very high energy neutrons of a fusion reactor. This paper describes irradiation capsules for mechanical property specimens used in the HFIR and the ORR. A neutron spectral tailoring experiment to achieve the fusion reactor He:dpa ratio will be discussed
Products of fission, fusion and deep inelastic reactions
International Nuclear Information System (INIS)
Factors which influence the yields in heavy ion reactions such as fusion, fission fragment production and deep inelastic reactions are considered in the context of the design of spectroscopic experiments. Factors examined include the suitability of a reaction for a particular application, the expected yield of the required nucleus, and parameters responsible for uncertainties in predicted yields. (U.K.)
Tunneling process in heavy-ion fusion and fission
Energy Technology Data Exchange (ETDEWEB)
Iwamoto, Akira [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kondratyev, V.; Bonasera, A.
1998-10-01
We present a model towards the many-body description of sub-barrier fusion and spontaneous fission based on the semiclassical Vlasov equation and the Feynman path integral method. We define suitable collective variables from the Vlasov solution and use the imaginary time technique for the dynamics below the Coulomb barrier. (author)
Brief review of the fusion--fission hybrid reactor
International Nuclear Information System (INIS)
Much of the conceptual framework of present day fusion-fission hybrid reactors is found in the original work of the early 1950's. Present day motivations for development are quite different. The role of the hybrid reactor is discussed as well as the current activities in the development program
Fission Product Decay Heat Calculations for Neutron Fission of 232Th
Son, P. N.; Hai, N. X.
2016-06-01
Precise information on the decay heat from fission products following times after a fission reaction is necessary for safety designs and operations of nuclear-power reactors, fuel storage, transport flasks, and for spent fuel management and processing. In this study, the timing distributions of fission products' concentrations and their integrated decay heat as function of time following a fast neutron fission reaction of 232Th were exactly calculated by the numerical method with using the DHP code.
Fission-Fusion Neutron Source Progress Report Sept 30, 2009
Energy Technology Data Exchange (ETDEWEB)
Chapline, G F; Daffin, F; Clark, R
2010-02-19
In this report the authors describe the progress made in FY09 in evaluating the feasibility of a new concept for using the DT fusion reaction to produce intense pulses of 14 MeV neutrons. In this new scheme the heating of the DT is accomplished using fission fragments rather than ion beams as in conventional magnet confinement fusion schemes or lasers in inertial confinement schemes. As a source of fission fragments they propose using a dust reactor concept introduced some time ago by one of us (RC). An attractive feature of this approach is that there is no need for a large auxiliary power source to heat the DT plasma to the point where self-sustaining fusion become possible. Their scheme does require pulsed magnetic fields, but generating these fields requires only a modest power source. The dust reactor that they propose using for their neutron source would use micron-sized UC pellets suspended in a vacuum as the reactor fuel. Surrounding the fuel with a moderator such as heavy water (D{sub 2}O) would allow the reactor to operate as a thermal reactor and require only modest amounts of HEU. The scheme for using fission fragments to generate intense pulses of 14 MeV neutrons is based on the fission fragment rocket idea. In the fission fragment rocket scheme it was contemplated that the fission fragments produced in a low density reactor core could be guided out of the reactor by large magnetic fields used to form a 'rocket exhaust'. Their adaptation of this idea for the purposes of making a neutron source involves using the fission fragments escaping from one side of a tandem magnet mirror to heat DT gas confined in the adjacent magnetic trap.
Fission-Fusion Neutron Source Progress Report Sept 30, 2009
International Nuclear Information System (INIS)
In this report the authors describe the progress made in FY09 in evaluating the feasibility of a new concept for using the DT fusion reaction to produce intense pulses of 14 MeV neutrons. In this new scheme the heating of the DT is accomplished using fission fragments rather than ion beams as in conventional magnet confinement fusion schemes or lasers in inertial confinement schemes. As a source of fission fragments they propose using a dust reactor concept introduced some time ago by one of us (RC). An attractive feature of this approach is that there is no need for a large auxiliary power source to heat the DT plasma to the point where self-sustaining fusion become possible. Their scheme does require pulsed magnetic fields, but generating these fields requires only a modest power source. The dust reactor that they propose using for their neutron source would use micron-sized UC pellets suspended in a vacuum as the reactor fuel. Surrounding the fuel with a moderator such as heavy water (D2O) would allow the reactor to operate as a thermal reactor and require only modest amounts of HEU. The scheme for using fission fragments to generate intense pulses of 14 MeV neutrons is based on the fission fragment rocket idea. In the fission fragment rocket scheme it was contemplated that the fission fragments produced in a low density reactor core could be guided out of the reactor by large magnetic fields used to form a 'rocket exhaust'. Their adaptation of this idea for the purposes of making a neutron source involves using the fission fragments escaping from one side of a tandem magnet mirror to heat DT gas confined in the adjacent magnetic trap.
International Nuclear Information System (INIS)
This report summarizes findings of the fusion-fission studies conducted for the Electric Power Research Institute by Battelle, Pacific Northwest Laboratories. This particular study focused on the evaluation of fissile material producing hybrids. Technical results of the evaluation of actinide burning are presented in a companion volume, Part B
International Nuclear Information System (INIS)
Highlights: • Fission yield data and uncertainty comparison between major nuclear data libraries. • Fission yield covariance generation through Bayesian technique. • Study of the effect of fission yield correlations on decay heat calculations. • Covariance information contribute to reduce fission pulse decay heat uncertainty. - Abstract: Fission product yields are fundamental parameters in burnup/activation calculations and the impact of their uncertainties was widely studied in the past. Evaluations of these uncertainties were released, still without covariance data. Therefore, the nuclear community expressed the need of full fission yield covariance matrices to be able to produce inventory calculation results that take into account the complete uncertainty data. State-of-the-art fission yield data and methodologies for fission yield covariance generation were researched in this work. Covariance matrices were generated and compared to the original data stored in the library. Then, we focused on the effect of fission yield covariance information on fission pulse decay heat results for thermal fission of 235U. Calculations were carried out using different libraries and codes (ACAB and ALEPH-2) after introducing the new covariance values. Results were compared with those obtained with the uncertainty data currently provided by the libraries. The uncertainty quantification was performed first with Monte Carlo sampling and then compared with linear perturbation. Indeed, correlations between fission yields strongly affect the uncertainty of decay heat. Eventually, a sensitivity analysis of fission product yields to fission pulse decay heat was performed in order to provide a full set of the most sensitive nuclides for such a calculation
Fusion-fission hybrid studies in the United States of America
International Nuclear Information System (INIS)
Systems and conceptual design studies have been carried out on the following three hybrid types: (1) The fission-suppressed hybrid, which maximizes fissile material produced (Pu or 233U) per unit of total nuclear power by suppressing the fission process and multiplying neutrons by (n,2n) reactions in materials like beryllium. (2) The fast-fission hybrid, which maximizes fissile material produced per unit of fusion power by maximizing fission of 238U (Pu is produced) in which twice the fissile atoms per unit of fusion power (but only a third per unit of nuclear power) are made. (3) The power hybrid, which amplifies power in the blanket for power production but does not produce fuel to sell. A series of studies led to a reference design of a fission-suppressed breeder that used liquid-lithium cooling of beryllium balls with thorium snap rings. Another series of studies considered a fission-suppressed, helium-cooled, molten-salt breeder design. Safety improvements for use in fast-fission designs were also identified. Low-burnup metal balls, which can be drained out of the blanket to passively cooled holding tanks, would be used in several of the above design concepts. Blanket designs not requiring reprocessing, called direct enrichment, were also studied. Breeding blanket designs for tokamak and tandem-mirror configurations were based on liquid-lithium, water, and helium cooling. Solid (U, Th, LiA102, Li2O) and liquid breeders (Li, LiF+ThF4) were considered. Studies indicate that as the predicted cost of the fission-suppressed fusion plant drops from twice a light-water reactor's (LWR) cost, the calculated breakeven price of uranium from the fusion breeder drops from $100/pound. A fusion plant costing 1.5 times an LWR is calculated to produce fuel at an equivalent price of $70/pound. An overall conclusion is that the deployment of fusion technology can cap the price of uranium. 18 refs, 12 figs, 4 tabs
Neutron dosimetry for radiation damage in fission and fusion reactors
International Nuclear Information System (INIS)
The properties of materials subjected to the intense neutron radiation fields characteristic of fission power reactors or proposed fusion energy devices is a field of extensive current research. These investigations seek important information relevant to the safety and economics of nuclear energy. In high-level radiation environments, neutron metrology is accomplished predominantly with passive techniques which require detailed knowledge about many nuclear reactions. The quality of neutron dosimetry has increased noticeably during the past decade owing to the availability of new data and evaluations for both integral and differential cross sections, better quantitative understanding of radioactive decay processes, improvements in radiation detection technology, and the development of reliable spectrum unfolding procedures. However, there are problems caused by the persistence of serious integral-differential discrepancies for several important reactions. There is a need to further develop the data base for exothermic and low-threshold reactions needed in thermal and fast-fission dosimetry, and for high-threshold reactions needed in fusion-energy dosimetry. The unsatisfied data requirements for fission reactor dosimetry appear to be relatively modest and well defined, while the needs for fusion are extensive and less well defined because of the immature state of fusion technology. These various data requirements are examined with the goal of providing suggestions for continued dosimetry-related nuclear data research
Fusion-Fission Burner for Transuranic Actinides
Choi, Chan
2013-10-01
The 14-MeV DT fusion neutron spectrum from mirror confinement fusion can provide a unique capability to transmute the transuranic isotopes from light water reactors (LWR). The transuranic (TRU) actinides, high-level radioactive wastes, from spent LWR fuel pose serious worldwide problem with long-term decay heat and radiotoxicity. However, ``transmuted'' TRU actinides can not only reduce the inventory of the TRU in the spent fuel repository but also generate additional energy. Typical commercial LWR fuel assemblies for BWR (boiling water reactor) and PWR (pressurized water reactor) measure its assembly lengths with 4.470 m and 4.059 m, respectively, while its corresponding fuel rod lengths are 4.064 m and 3.851 m. Mirror-based fusion reactor has inherently simple geometry for transmutation blanket with steady-state reactor operation. Recent development of gas-dynamic mirror configuration has additional attractive feature with reduced size in central plasma chamber, thus providing a unique capability for incorporating the spent fuel assemblies into transmutation blanket designs. The system parameters for the gas-dynamic mirror-based hybrid burner will be discussed.
Systems study of tokamak fusion--fission reactors
Energy Technology Data Exchange (ETDEWEB)
Tenney, F.H.; Bathke, C.G.; Price, W.G. Jr.; Bohlke, W.H.; Mills, R.G.; Johnson, E.F.; Todd, A.M.M.; Buchanan, C.H.; Gralnick, S.L.
1978-11-01
This publication reports the results of a two to three year effort at a systematic analysis of a wide variety of tokamak-driven fissioning blanket reactors, i.e., fusion--fission hybrids. It addresses the quantitative problems of determining the economically most desirable mix of the two products: electric power and fissionable fuel and shows how the price of electric power can be minimized when subject to a variety of constraints. An attempt has been made to avoid restricting assumptions, and the result is an optimizing algorithm that operates in a six-dimensional parameter space. Comparisons are made on sets of as many as 100,000 distinct machine models, and the principal results of the study have been derived from the examination of several hundred thousand possible reactor configurations.
Systems study of tokamak fusion--fission reactors
International Nuclear Information System (INIS)
This publication reports the results of a two to three year effort at a systematic analysis of a wide variety of tokamak-driven fissioning blanket reactors, i.e., fusion--fission hybrids. It addresses the quantitative problems of determining the economically most desirable mix of the two products: electric power and fissionable fuel and shows how the price of electric power can be minimized when subject to a variety of constraints. An attempt has been made to avoid restricting assumptions, and the result is an optimizing algorithm that operates in a six-dimensional parameter space. Comparisons are made on sets of as many as 100,000 distinct machine models, and the principal results of the study have been derived from the examination of several hundred thousand possible reactor configurations
Ceramic materials for fission and fusion nuclear reactors
International Nuclear Information System (INIS)
A general survey on the ceramics for nuclear applications is presented. For the fission nuclear reactor, the ceramics materials are almost totally used as fuel e.g. (U,Pu)O2; other types of ceramics, e.g. Uranium-Plutonium carbide and nitride, have been investigated as potential nuclear fuels. The (U,Pu)N compound is to be the fuel for the space nuclear power reactor in the U.S.A. For the fusion nuclear reactor, the ceramics should be the fundamental materials for many components: first wall, breeder, RF heating systems, insulant and shielding parts, etc. In recent years many countries are involved on the research and development of ceramic compounds with the principal purpose of being used in the fusion powerplant (year 2010-2020 ?). An effort has been even made to verify if it is possible to use more ceramic components in the fission nuclear plant (probably differntly disigned) to improve the safety level
Influence of differences in the proton and neutron distributions on nuclear fusion and fission
International Nuclear Information System (INIS)
This thesis work is centred on some essential ingredients of a theoretical description of the reaction dynamics of the nuclear fusion and fission process, such as the interaction potential between projectile and target nuclei for fusion and the deformation energy landscape in a multidimensional space for the fission process. We have in particular evaluated the importance of the difference between the neutron and proton density distributions on these 2 processes. The fusion potential between the two interacting nuclei is obtained through the nucleon densities, determined in a self-consistent way through semiclassical density variational calculations for a given effective nucleon-nucleon effective interaction of the Skyrme type. These fusion barriers can then be used in a Langevin formalism to evaluation fusion cross sections. For the fission process it turns out to be essential to allow for the large variety of shapes which appear between the nuclear ground state and the the scission configuration. We show that a shape parametrisation taking into account elongation, as well as possible neck formation, left-right asymmetry and non-axiality allows a precise description of this phenomena in the framework of the macroscopic-microscopic approach. We are thus able to enrich the expression of the liquid-drop type energy through a term which describes the variation of the nuclear energy due to a deformation difference between the proton and neutron distribution. The resulting reduction of the fission barriers is only of the order of one MeV but this can easily cause a change in the fission cross-section by an order of magnitude and thus plays a capital role for the stability of super-heavy of exotic nuclei. (author)
Role of mitochondrial lipids in guiding fission and fusion
Frohman, Michael A.
2014-01-01
Clinically-important links have been established between mitochondrial function and cardiac physiology and disease in the context of signaling mechanisms, energy production, and muscle cell development. The proteins and processes that drive mitochondrial fusion and fission are now known to have emergent functions in intracellular calcium homeostasis, apoptosis, vascular smooth muscle cell proliferation, myofibril organization, and Notch-driven cell differentiation, all key issues in cardiac d...
Measurement of tritium production rate distribution for a fusion-fission hybrid conceptual reactor
International Nuclear Information System (INIS)
A fusion-fission hybrid conceptual reactor is established. It consists of a DT neutron source and a spherical shell of depleted uranium and hydrogen lithium. The tritium production rate (TPR) distribution in the conceptual reactor was measured by DT neutrons using two sets of lithium glass detectors with different thicknesses in the hole in the vertical direction with respect to the D+ beam of the Cockcroft-Walton neutron generator in direct current mode. The measured TPR distribution is compared with the calculated results obtained by the three-dimensional Monte Carlo code MCNP5 and the ENDF/B-Ⅵ data file. The discrepancy between the measured and calculated values can be attributed to the neutron data library of the hydrogen lithium lack S(α, β) thermal scattering model, so we show that a special database of low-energy and thermal neutrons should be established in the physics design of fusion-fission hybrid reactors. (authors)
Measurement of tritium production rate distribution for a fusion-fission hybrid conceptual reactor
Institute of Scientific and Technical Information of China (English)
WANG Xin-Hua; GUO Hai-Ping; MOU Yun-Feng; ZHENG Pu; LIU Rong; YANG Xiao-Fei; YANG Jian
2013-01-01
A fusion-fission hybrid conceptual reactor is established.It consists of a DT neutron source and a spherical shell of depleted uranium and hydrogen lithium.The tritium production rate (TPR) distribution in the conceptual reactor was measured by DT neutrons using two sets of lithium glass detectors with different thicknesses in the hole in the vertical direction with respect to the D+ beam of the Cockcroft-Walton neutron generator in direct current mode.The measured TPR distribution is compared with the calculated results obtained by the threedimensional Monte Carlo code MCNP5 and the ENDF/B-Ⅵ data file.The discrepancy between the measured and calculated values can be attributed to the neutron data library of the hydrogen lithium lack S(α,β) thermal scattering model,so we show that a special database of low-energy and thermal neutrons should be established in the physics design of fusion-fission hybrid reactors.
Some Calculations for Cold Fusion Superheavy Elements
X. H. Zhong; Li, L.; Ning, P. Z.
2004-01-01
The Q value and optimal exciting energy of the hypothetical superheavy nuclei in cold fusion reaction are calculated with relativistic mean field model and semiemperical shell model mass equation(SSME) and the validity of the two models is tested. The fusion barriers are also calculated with two different models and reasonable results are obtained. The calculations can give useful references for the experiments in the superheavy nuclei synthesized in cold fusion reactions.
Radioactive waste transmutation in a fission-fusion hybrid system
International Nuclear Information System (INIS)
A fission-fusion hybrid reactor is proposed for recycling and transmutation of highly radioactive waste. Two fusion systems were evaluated. A Tokamak, based on magnetic confinement, and another based on inertial confinement. These systems have been modified and designed to place a transmutation layer loaded with transuranic elements from spent fuel of nuclear power plants. The transmutation layer is the first presented in specific literature to be used with fuel reprocessed by the method UREX + and further spiked with depleted uranium or thorium to reduce the amount of fissile material in order to keep a subcritical system. The evaluations were carried out by varying geometric parameters such as the thickness of transmutation layer and the radius of the fuel rod. Depending on the case this variations increase the efficiency to reduce the transuranic contained in the fuel. The results show the possibility of reducing the transuranic for each model and transmutation efficiency compared to the initial amount of recycled fuel for each fusion reactor. Furthermore, a comparison of both hybrid fusion-fission systems is performed in order to find the best system to reduce transuranics efficiently. (author)
Role of mitochondrial lipids in guiding fission and fusion.
Frohman, Michael A
2015-03-01
Clinically important links have been established between mitochondrial function and cardiac physiology and disease in the context of signaling mechanisms, energy production, and muscle cell development. The proteins and processes that drive mitochondrial fusion and fission are now known to have emergent functions in intracellular calcium homeostasis, apoptosis, vascular smooth muscle cell proliferation, myofibril organization, and Notch-driven cell differentiation, all key issues in cardiac disease. Moreover, decreasing fission may confer protection against ischemic heart disease, particularly in the setting of obesity, diabetes, and heart failure. The importance of lipids in controlling mitochondrial fission and fusion is increasingly becoming appreciated. Roles for the bulk and signaling lipids cardiolipin, phosphatidylethanolamine, phosphatidic acid, diacylglycerol, and lysophosphatidic acid and the enzymes that synthesize or metabolize them in the control of mitochondrial shape and function are reviewed here. A number of diseases have been linked to loss-of-function alleles for a subset of the enzymes, emphasizing the importance of the lipid environment in this context. PMID:25471483
Pink1 regulates mitochondrial dynamics through interaction with the fission/fusion machinery
Yang, Yufeng; Ouyang, Yingshi; Yang, Lichuan; Beal, M. Flint; McQuibban, Angus; Vogel, Hannes; Lu, Bingwei
2008-01-01
Mitochondria form dynamic tubular networks that undergo frequent morphological changes through fission and fusion, the imbalance of which can affect cell survival in general and impact synaptic transmission and plasticity in neurons in particular. Some core components of the mitochondrial fission/fusion machinery, including the dynamin-like GTPases Drp1, Mitofusin, Opa1, and the Drp1-interacting protein Fis1, have been identified. How the fission and fusion processes are regulated under norma...
Dynamical approach to fusion-fission process in superheavy mass region
Directory of Open Access Journals (Sweden)
Aritomo Y.
2012-10-01
Full Text Available In order to describe heavy-ion fusion reactions around the Coulomb barrier with an actinide target nucleus, we propose a model which combines the coupled-channels approach and a fluctuation-dissipation model for dynamical calculations. This model takes into account couplings to the collective states of the interacting nuclei in the penetration of the Coulomb barrier and the subsequent dynamical evolution of a nuclear shape from the contact configuration. In the fluctuation-dissipation model with a Langevin equation, the effect of nuclear orientation at the initial impact on the prolately deformed target nucleus is considered. Fusion-fission, quasifission and deep quasifission are separated as different Langevin trajectories on the potential energy surface. Using this model, we analyze the experimental data for the mass distribution of fission fragments (MDFF in the reaction of 36S+238U at several incident energies around the Coulomb barrier.
Theory of competition between fusion and quasi-fission in a heavy fusing system
Díaz-Torres, A
2006-01-01
A theory of the competition between fusion and quasi-fission in a heavy fusing system is proposed, which is based on a master equation and the two-center shell model. Fusion and quasi-fission arise from a diffusion process in an ensemble of nuclear shapes evolving towards the thermal equilibrium. The master equation describes the diffusion of the nuclear shapes due to quantum and thermal fluctuations. Other crucial physical effects like dissipation, ground-state shell effects, diabatic effects and rotational effects are also incorporated into the theory. The fusing system moves in a dynamical (time-dependent) collective potential energy surface which is initially diabatic and gradually becomes adiabatic. The microscopic ingredients of the theory are obtained with a realistic two-center shell model based on Woods-Saxon potentials. Numerical calculations for several reactions leading to $^{256}$No are discussed. Among other important conclusions, the results indicate that (i) the diabatic effects play a very im...
Improved calculation of the prompt fission neutron spectrum from the spontaneous fission of 252Cf
International Nuclear Information System (INIS)
An improved calculation is presented for the prompt fission neutron spectrum N(E) from the spontaneous fission of 252Cf. In this calculation the fission-spectrum model of Madland and Nix is used, but with several improvements leading to a physically more accurate representation of the spectrum. Specifically, the contributions to N(E) from the entire fission-fragment mass and charge distributions will be calculated instead of calculating on the basis of a seven-point approximation to the peaks of these distributions as has been done in the past. Therefore, values of the energy release in fission, fission-fragment kinetic energy, nuclear level density, and compound nucleus cross section for the inverse process will be considered on a point-by-point basis over the fragment yield distributions instead of considering averages of these quantities over the peaks of the distributions. Particular attention will be given to the energy-dependent compound nucleus cross sections and to the nuclear level density model. Other refinements to the calculation of N(E) will also be discussed. Results will be presented and compared with earlier calculations of the spectrum and with recent experimental measurements of the spectrum. 9 figs
Fusion--fission hybrid reactors based on the laser solenoid
International Nuclear Information System (INIS)
Fusion-fission reactors, based on the laser solenoid concept, can be much smaller in scale than their pure fusion counterparts, with moderate first-wall loading and rapid breeding capabilities (1 to 3 tonnes/yr), and can be designed successfully on the basis of classical plasma transport properties and free-streaming end-loss. Preliminary design information is presented for such systems, including the first wall, pulse coil, blanket, superconductors, laser optics, and power supplies, accounting for the desired reactor performance and other physics and engineering constraints. Self-consistent point designs for first and second generation reactors are discussed which illustrate the reactor size, performance, component parameters, and the level of technological development required
Calculation of fission reactions within the MM-RNR model
International Nuclear Information System (INIS)
In the past fission-fragment properties and cross-sections for 235,238U(n, f), 237Np(n, f), 239Pu(n, f) and 252Cf(SF) have been investigated. The interpretation of the experimental data in the frame of the multi-modal random neck-rupture (MM-RNR) model has been incorporated into the most recent evaluation exercise on neutron-induced fission cross-section and prompt-neutron emission data in the actinide region of the chart of nuclides. The three most dominant fission modes were considered, the two asymmetric standard I (S1) and standard II (S2) modes and the symmetric superlong (SL) mode, namely. Except for 252Cf, de-convoluted modal fission cross-sections as well as prompt neutron multiplicity and spectra have been calculated in the energy range from 0.01 MeV to 5.5 MeV in excellent agreement with experimental data. In addition, the obtained fission-mode branching ratios allow the calculation of fission-fragment yield and energy distributions where no experimental data exist. Most recently the first ever-direct measurement of the neutron-induced fission cross-section of 233Pa has been performed at IRMM. The subsequent evaluation suggests a radical revision of today's evaluated data files. (author)
Kramer, Kevin James
This study investigates the neutronics design aspects of a hybrid fusion-fission energy system called the Laser Fusion-Fission Hybrid (LFFH). A LFFH combines current Laser Inertial Confinement fusion technology with that of advanced fission reactor technology to produce a system that eliminates many of the negative aspects of pure fusion or pure fission systems. When examining the LFFH energy mission, a significant portion of the United States and world energy production could be supplied by LFFH plants. The LFFH engine described utilizes a central fusion chamber surrounded by multiple layers of multiplying and moderating media. These layers, or blankets, include coolant plenums, a beryllium (Be) multiplier layer, a fertile fission blanket and a graphite-pebble reflector. Each layer is separated by perforated oxide dispersion strengthened (ODS) ferritic steel walls. The central fusion chamber is surrounded by an ODS ferritic steel first wall. The first wall is coated with 250-500 mum of tungsten to mitigate x-ray damage. The first wall is cooled by Li17Pb83 eutectic, chosen for its neutron multiplication and good heat transfer properties. The Li17Pb 83 flows in a jacket around the first wall to an extraction plenum. The main coolant injection plenum is immediately behind the Li17Pb83, separated from the Li17Pb83 by a solid ODS wall. This main system coolant is the molten salt flibe (2LiF-BeF2), chosen for beneficial neutronics and heat transfer properties. The use of flibe enables both fusion fuel production (tritium) and neutron moderation and multiplication for the fission blanket. A Be pebble (1 cm diameter) multiplier layer surrounds the coolant injection plenum and the coolant flows radially through perforated walls across the bed. Outside the Be layer, a fission fuel layer comprised of depleted uranium contained in Tristructural-isotropic (TRISO) fuel particles having a packing fraction of 20% in 2 cm diameter fuel pebbles. The fission blanket is cooled by
Cluster fusion-fission dynamics in the Singapore stock exchange
Teh, Boon Kin; Cheong, Siew Ann
2015-10-01
In this paper, we investigate how the cross-correlations between stocks in the Singapore stock exchange (SGX) evolve over 2008 and 2009 within overlapping one-month time windows. In particular, we examine how these cross-correlations change before, during, and after the Sep-Oct 2008 Lehman Brothers Crisis. To do this, we extend the complete-linkage hierarchical clustering algorithm, to obtain robust clusters of stocks with stronger intracluster correlations, and weaker intercluster correlations. After we identify the robust clusters in all time windows, we visualize how these change in the form of a fusion-fission diagram. Such a diagram depicts graphically how the cluster sizes evolve, the exchange of stocks between clusters, as well as how strongly the clusters mix. From the fusion-fission diagram, we see a giant cluster growing and disintegrating in the SGX, up till the Lehman Brothers Crisis in September 2008 and the market crashes of October 2008. After the Lehman Brothers Crisis, clusters in the SGX remain small for few months before giant clusters emerge once again. In the aftermath of the crisis, we also find strong mixing of component stocks between clusters. As a result, the correlation between initially strongly-correlated pairs of stocks decay exponentially with average life time of about a month. These observations impact strongly how portfolios and trading strategies should be formulated.
Calculation of fission fragment angular anisotropy in heavy-ion induced fission
International Nuclear Information System (INIS)
Fission fragment angular anisotropies from 16O + 232Th, 12C + 236U, 11B + 237Np, 14N + 232Th, 11B + 235U and 12C + 232Th systems were calculated by means of the standard saddle point statistical model (SSPSM). The results were obtained with and without neutron emission correction in the reactions, and comparisons were made with the corresponding experimental data. The normal and anomalous behaviors of fission fragment anisotropies are extensively discussed. (author)
The Impact of Fission on R-Process Calculations
Eichler, M.; Arcones, A.; Käppeli, R.; Korobkin, O.; Liebendörfer, M.; Martinez-Pinedo, G.; Panov, I. V.; Rauscher, T.; Rosswog, S.; Thielemann, F.-K.; Winteler, C.
2016-01-01
We have performed r-process calculations in neutron star mergers (NSM) and jets of magnetohydrodynamically driven (MHD) supernovae. In these very neutron-rich environments the fission model of heavy nuclei has an impact on the shape of the final abundance distribution and the second r-process peak in particular. We have studied the effect of different fission fragment mass distribution models in calculations of low-Ye ejecta, ranging from a simple parametrization to extensive statistical treatments (ABLA07). The r-process path ends when it reaches an area in the nuclear chart where fission dominates over further neutron captures. The position of this point is determined by the fission barriers and the neutron separation energies of the nuclei involved. As these values both depend on the choice of the nuclear mass model, so does the r-process path. Here we present calculations using the FRDM (Finite Range Droplet Model) and the ETFSI (Extended Thomas Fermi with Strutinsky Integral) mass model with the related TF and ETFSI fission barrier predictions. Utilizing sophisticated fission fragment distribution leads to a highly improved abundance distribution.
Coil Design and Related Studies for the Fusion-Fission Reactor Concept SFLM Hybrid
Hagnestål, Anders
2012-01-01
A fusion-fission (hybrid) reactor is a combination of a fusion device and a subcritical fission reactor, where the fusion device acts as a neutron source and the power is mainly produced in the fission core. Hybrid reactors may be suitable for transmutation of transuranic isotopes in the spent nuclear fuel, due to the safety margin on criticality imposed by the subcritical fission core. The SFLM Hybrid project is a theoretical project that aims to point out the possibilities with steady-state...
Fission life-time calculation using a complex absorbing potential
Directory of Open Access Journals (Sweden)
Scamps Guillaume
2016-01-01
Full Text Available A comparison between the semi-classical approximation and the full quantum calculation with a complex absorbing potential is made with a model of the fission of 258Fm. The potential barrier is obtained with the constrained Skyrme HF+BCS theory. The life-time obtained by the two calculations agree with each other the difference being only by 25%.
Fission life-time calculation using a complex absorbing potential
Scamps, Guillaume
2015-01-01
A comparison between the semi-classical approximation and the full quantum calculation with a complex absorbing potential is made with a model of the fission of 258Fm. The potential barrier is obtained with the constrained Skyrme HF+BCS theory. The life-time obtained by the two calculations agree with each other the difference being only by 25%.
International Nuclear Information System (INIS)
It is now well known that many reactions giving measurable fusion cross-sections also show a fission of the compound system formed, similar to the low energy fission of the known fissioning nuclei. Recently, both the fusion excitation functions and the mass equilibration in the fragmentation of the composite system were measured for a large number of systems with 94208Pb on different targets of 26Mg, 48Ca, 50Ti, 52Cr, 58Fe and 64Ni. From a theoretical point of view, it is relevant to ask the question: how do the colliding nuclei fuse and then why does the compound system formed fission instead of going to the ground state to give a stable system. In this Letter, we attempt to show that the fusion of asymmetric colliding nuclei is due to the overcoming of the interaction barriers in adiabatic potentials and the fission of the compound system should perhaps occur as a sudden process, like the one in the spontaneous fission phenomenon. We have made our calculations for the compound systems with 102<=Z<=110 and for the asymmetric target-projectile combinations of the experiments of Ref. 1, using the fragmentation theory whose basis is the asymmetric two-centre shell model
International Nuclear Information System (INIS)
We are studying the use of a Laser Inertial-confinement Fusion Engine (LIFE) to drive a hybrid fusion-fission system that can generate electrical power and/or burn nuclear waste. The system uses the neutrons from laser driven ICF to produce tritium and to drive nuclear reactions in a subcritical fission blanket. The fusion neutron source obviates the need for a self-sustaining chain reaction in the fission blanket. Either fissile or fertile could be used as fission fuel, thus eliminating the need for isotopic enrichment. The 'driven' system potentially allows very high levels of burnup to be reached, extracting a large fraction of the available energy in the fission fuel without the need for reprocessing. In this note, we discuss the radionuclide inventory of a depleted uranium (DU) fuel burned to greater than 95% FIMA (Fissions per Initial heavy Metal Atom), the implications for thermal management of the resulting waste, and the implications of this waste for meeting the dose standards for releases from a geological repository for high-level waste. The fission waste discussed here would be that produced by a LIFE hybrid with a 500-MW fusion source. The fusion neutrons are multiplied and moderated by a sequence of concentric shells of materials before encountering the fission fuel, and fission in this region is largely due to thermal neutrons. The fission blanket consists of 40 metric tons (MT) of DU, assumed to be in the form of TRISO-like UOC fuel particles embedded in 2-cm-diameter graphite pebbles. (It is recognized that TRISO-based fuel may not reach the high burnup of the fertile fuel considered here, and other fuel options are being investigated. We postulate the existence of a fuel that can reach >95% FIMA so that the waste disposal implications of high burnup can be assessed.) The engine and plant design considered here would receive one load of fission fuel and produce ∼2 GWt of power (fusion + fission) over its 50- to 70-year lifetime. Neutron and
1978 source book for fusion--fission hybrid systems. Executive summary
International Nuclear Information System (INIS)
The 1978 Source Book for Fusion--Fission Hybrid Systems was prepared by United Engineers and Constructors Inc. for the U.S. Department of Energy and the Electric Power Research Institute. It reviews the current status of fusion--fission hybrid reactors, and presents the prevailing views of members of the fusion community on the RD and D timetable required for the development and commercialization of fusion--fission hybrids. The results presented are based on a review of related references as well as interviews with recognized experts in the field. Contributors from the academic and industrial communities are listed
Control of a laser inertial confinement fusion-fission power plant
Energy Technology Data Exchange (ETDEWEB)
Moses, Edward I.; Latkowski, Jeffery F.; Kramer, Kevin J.
2015-10-27
A laser inertial-confinement fusion-fission energy power plant is described. The fusion-fission hybrid system uses inertial confinement fusion to produce neutrons from a fusion reaction of deuterium and tritium. The fusion neutrons drive a sub-critical blanket of fissile or fertile fuel. A coolant circulated through the fuel extracts heat from the fuel that is used to generate electricity. The inertial confinement fusion reaction can be implemented using central hot spot or fast ignition fusion, and direct or indirect drive. The fusion neutrons result in ultra-deep burn-up of the fuel in the fission blanket, thus enabling the burning of nuclear waste. Fuels include depleted uranium, natural uranium, enriched uranium, spent nuclear fuel, thorium, and weapons grade plutonium. LIFE engines can meet worldwide electricity needs in a safe and sustainable manner, while drastically shrinking the highly undesirable stockpiles of depleted uranium, spent nuclear fuel and excess weapons materials.
An analysis of tritium and fissile fuel exchange in fusion-fission systems
International Nuclear Information System (INIS)
A model is developed to describe the tritium and fissile fuel flow in a fusion-fission system which consists of a fusion (hybrid) reactor, tritium production (fission) reactors, and (fission) power reactors. The fusion reactor provides all of the fissile fuel for the tritium production and power reactors. Tritium production reactors assure that the system is self sufficient in tritium even if the fusion reactor is not self sufficient. Studies were performed to determine the changes in the cost of electricity from the system as the tritium breeding responsibility varies between the fusion reactor and the tritium production reactors. Allowance for system growth was accomplished with the use of a compound doubling time parameter. Results indicate that the cost of electricity from certain fusion-fission systems may be comparable to that from other advanced systems expected in the same era
International Nuclear Information System (INIS)
The nuclear performance of a fusion-fission hybrid reactor having a molten salt composed of Na-Th-F-Be as the blanket fertile material and operating with a catalyzed DD plasma is compared to a similar system utilizing a Li-Th-F-Be salt and operating with a DT plasma. The production of fissile fuel via the 232Th-233U fuel cycle was considered on the basis of its potential nonproliferation aspects. The calculations were performed using one-dimensional discrete ordinates methods to compare neutron balances, fuel producion rates, energy deposition rates, and the radiation damage in the reactor structure
Impact of fusion-fission hybrids on world nuclear future
International Nuclear Information System (INIS)
An investigation has been conducted to examine the impact of fusion-fission hybrids on world nuclear future. The primary objectives of this investigation have been: (1) to determine whether hybrids can allow us to meet the projected nuclear component of the world energy demand within current estimates of uranium resources without fast breeders, and (2) to identify the preferred hybrid concept from a resource standpoint. The results indicate that hybrids have the potential to lower the world uranium demand to values well below the resource base. However, the time window for hybrid introduction is quite near and narrow (2000-2020). If historical market penetration rates are assumed, the demand will not be met within the resource base unless hybrids are coupled to the breeders. The results also indicate that from a resource standpoint hybrids which breed their own tritium and have a low blanket energy multiplication are preferable. (orig.)
Nuclear viscosity and heavy-ion fusion-fission reactions
International Nuclear Information System (INIS)
Recently measured properties of the pre-scission particle emission from heavy-ion fusion-fission reactions of systems with A ∼ 200 were analysed using the latest version of the statistical model code JOANNE. Simultaneous fits to the multiplicities of pre-scission neutrons, protons and alpha-particles and their mean kinetic energies can be obtained when the deformation dependence of both the particle transmission coefficients and particle binding energies are taken into account. The emission of protons and alpha-particles is found to be suppressed relative to the neutron emission with increasing nuclear deformation. If the Fermi-gas level density parameter α is assumed to be independent of deformation then the experimental pre-scission particle data are consistent with α = A/(8.8± 0.5) MeV-1, a total fission dynamical time scale of 18 ± 5X10-21 s with a pre-saddle time of 5 ± 2x10-21 s and a saddle-to-scission transition time of 13 ±4x10-21 s. These time scales, along with the widths of isoscalar giant quadrupole and octupole resonances and the kinetic energy of fission fragments from systems with A ∼ 200, are consistent with the surface-plus-window dissipation model with the full one-body wall formula scaling factor ks ∼ 0.3 for compact configurations and ks ∼ 0.6 for highly deformed nuclear shapes. 25 refs., 1 tab., 10 figs
Temperature transients of a fusion-fission ITER pebble bed reactor in loss of coolant accident
International Nuclear Information System (INIS)
In this preliminary scoping study, post-accident temperature transients of several fusion-fission designs utilizing ITER-FEAT-like parameters and fission pebble bed fuel technology are examined using a 1-D cylindrical MATLAB heat transfer code along with conventional fission decay heat approximations. Scenarios studied include systems with no additional passive safety features to systems with melting reflectors designed to increase emissivity after reaching a specified temperature. Results show that for a total fission power of ∼1400-2800 MW, two of the realistic variants investigated are passively safe. The crucial time, defined as the time when either any structural part of the fusion-fission tokamak reaches melting point, or when the pebble fuel reaches 1873 K, ranges from 5.7 to 76 h for the unsafe configurations. Additionally, it is illustrated that, fundamentally, the LOCA characteristics of pure fission pebble beds and fusion-fission pebble beds are different. Namely, the former depends on the pebble fuel's large thermal capacity, along with external radiation and natural convective cooling, while the latter depends significantly more on the tokamak's sizeable total internal heat capacity. This difference originates from the fusion-fission reactor's conflicting goal of having to minimize heat transfer to the magnets during normal operation. These results are discussed in the context of overall fusion-fission reactor design and safety
International Nuclear Information System (INIS)
An EPRI Ad Hoc Panel met in Asilomar, California for a three day general discussion of topics of particular interest to utility representatives. The three main topics considered were: (1) the possibility of advanced fuel fusion reactors, (2) fusion-fission hybrid breeders, and (3) small fusion power reactors. The report describes the ideas that evolved on these three topics. An example of a ''neutron less'' fusion reactor using the p-11B fuel cycle is described along with the critical questions that need to be addressed. The importance to the utility industry of using fusion neutrons to breed fission fuel for LWRs is outlined and directions for future EPRI research on fusion-fission systems are recommended. The desirability of small fusion power reactors to enable the early commercialization of fusion and for satisfying users' needs is discussed. Areas for possible EPRI research to help achieve this goal are presented
Mini-fission fusion explosive devices (mini-nukes) for nuclear pulse propulsion
Winterberg, F.
2005-11-01
Nuclear pulse propulsion demands low-yield nuclear explosive devices. Because the critical mass of a fission explosive is rather large, this leads to extravagant fission devices with a very low fuel burn-up. For non-fission ignited pure fusion microexplosions the problem is the large ignition apparatus (laser, particle beam, etc.). Fission ignited large fusion explosive devices are for obvious reasons even less desirable. A third category (mini-nukes) are devices where the critical mass of the fission explosive is substantially reduced by its coupling to a DT fusion reaction, with the DT fusion neutrons increasing the fission rate. Whereas in pure fission devices a reduction of the critical mass is achieved by the implosive compression of the fissile core with a chemical high explosive, in the third category the implosion must at the same time heat the DT surrounding the fissile core to a temperature of ⩾107K, at which enough fusion neutrons are generated to increase the fission rate which in turn further increases the temperature and fusion neutron production rate. As has been shown by the author many years ago, such mini-nukes lead to astonishingly small critical masses. In their application to nuclear pulse propulsion the combustion products from the chemical high explosive are further heated by the neutrons and are becoming part of the propellant.
Calculation of vapor pressure of fission product fluorides and oxyfluorides
International Nuclear Information System (INIS)
The equilibrium diagrams of the condensed phases - solid and liquid - and vapor phase are collected for the principal fluorides and oxyfluorides of fission product elements (atomic number from 30 to 66). These diagrams are used more particularly in fuel reprocessing by fluoride volatility process. Calculations and curves (vapor pressure in function of temperature) are processed using a computer program given in this report
Calculation of fusion product angular correlation coefficients for fusion plasmas
International Nuclear Information System (INIS)
The angular correlation coefficients for fusion products are calculated in the cases of Maxwellian and beam-target plasmas. Measurement of these coefficients as a localized ion temperature or fast-ion diagnostic is discussed. 8 refs., 7 figs., 1 tab
On the proliferation issues of a fusion fission fuel factory using a molten salt
International Nuclear Information System (INIS)
The fusion fission fuel factory (FFFF) is a hybrid fusion fission reactor using a neutron source, which is in this case taken similar to the source of the Power Plant Conceptual Study - Water Cooled Lithium Lead (PPCS-A) design, for fissile material production instead of tritium self-sufficiency. As breeding blanket the first wall of the ITER design is attached to a molten salt zone, in which ThF4 and UF4 solute salts are transported by a LiF-BeF2 solvent salt. For this blanket design, the fissile material is assessed in quantity and quality for both the Th-U and the U-Pu fuel cycle. The transport of the initial D-T fusion neutrons and the reaction rates in this breeding blanket are simulated with the Monte Carlo code MCNP4c2. The isotopic evolution of the actinides is calculated with the burn-up code ORIGEN-S. For the Th-U cycle the bred material output remains below 10 g/h with a 232U impurity level of 30 ppm, while for the U-Pu cycle supergrade material is produced at a rate up to 100 g/h.
Nuclear energy and fusion-fission hybrid reactor for pure energy production
International Nuclear Information System (INIS)
The next two decades are very critical for nuclear energy development. The commercial fast reactor may be in use around 2035; it is also possible that magnetically confined fusion, laser fusion and z-pinch fusion will be demonstrated at that time. A fusion demonstration reactor can be a pure fusion or a fusion-fission hybrid. The latter can lower the fusion power and mitigate the radiation damage of high energy neutrons to materials. On the other hand, the supply of deuterium and tritium as fuel for fusion can only last a few hundred years. We describe here a hybrid for pure energy use which can make full use of uranium and is proliferation resistant, as no separation of uranium and plutonium is needed in post-processing. The union of fission, fusion, and a pure energy hybrid can contribute to the large scale use of nuclear energy in the near future, and supply mankind for more than a thousand years. (authors)
Some safety studies for conceptual fusion--fission hybrid reactors. Final report
International Nuclear Information System (INIS)
The objective of this study was to make a preliminary examination of some potential safety questions for conceptual fusion-fission hybrid reactors. The study and subsequent analysis was largely based upon reference to one design, a conceptual mirror fusion-fission reactor, operating on the deuterium-tritium plasma fusion fuel cycle and the uranium-plutonium fission fuel cycle. The blanket is a fast-spectrum, uranium carbide, helium cooled, subcritical reactor, optimized for the production of fissile fuel. An attempt was made to generalize the results wherever possible
Radiological Dose Calculations for Fusion Facilities
Energy Technology Data Exchange (ETDEWEB)
Michael L. Abbott; Lee C. Cadwallader; David A. Petti
2003-04-01
This report summarizes the results and rationale for radiological dose calculations for the maximally exposed individual during fusion accident conditions. Early doses per unit activity (Sieverts per TeraBecquerel) are given for 535 magnetic fusion isotopes of interest for several release scenarios. These data can be used for accident assessment calculations to determine if the accident consequences exceed Nuclear Regulatory Commission and Department of Energy evaluation guides. A generalized yearly dose estimate for routine releases, based on 1 Terabecquerel unit releases per radionuclide, has also been performed using averaged site parameters and assumed populations. These routine release data are useful for assessing designs against US Environmental Protection Agency yearly release limits.
Fusion-fission probabilities, cross sections and structure notes of super-heavy nuclei
Kowal, Michał; Jachimowicz, Piotr; Skalski, Janusz; Siwek-Wilczyńska, Krystyna; Wilczyński, Janusz
2016-01-01
Fusion - fission probabilities in the synthesis of heaviest elements are discussed in the context of the latest experimental reports. Cross sections for superheavy nuclei are evaluated using "Fusion by Diffusion" (FBD) model. Predictive power of this approach is shown for experimentally known Lv, Og isotopes and predictions given for Z=119,120. Ground state and saddle point properties as: masses, shell corrections, pairing energies and deformations necessary for cross section estimations are calculated systematically within the multidimensional microscopic - macroscopic method based on the deformed Woods-Saxon single particle potential. In the frame of FBD approach predictions for production of elements heavier than Z = 118 are not too optimistic. For this reason, and because of high instability of superheavy nuclei, we comment on some structure effects, connected with the K-isomerism phenomenon which could lead to a significant increase in the stability of these systems.
Neutronics analysis of water-cooled energy production blanket for a fusion-fission hybrid reactor
International Nuclear Information System (INIS)
Neutronics calculations were performed to analyse the parameters of blanket energy multiplication factor (M) and tritium breeding ratio (TBR) in a fusion-fission hybrid reactor for energy production named FDS (Fusion-Driven hybrid System)-EM (Energy Multiplier) blanket. The most significant and main goal of the FDS-EM blanket is to achieve the energy gain of about 1 GWe with self-sustaining tritium, i.e. the M factor is expected to be ∼90. Four different fission materials were taken into account to evaluate M in subcritical blanket: (i) depleted uranium, (ii) natural uranium, (iii) enriched uranium, and (iv) Nuclear Waste (transuranic from 33 000 MWD/MTU PWR (Pressurized Water Reactor) and depleted uranium) oxide. These calculations and analyses were performed using nuclear data library HENDL (Hybrid Evaluated Nuclear Data Library) and a home-developed code VisualBUS. The results showed that the performance of the blanket loaded with Nuclear Waste was most attractive and it could be promising to effectively obtain tritium self-sufficiency and a high-energy multiplication.
Energy Technology Data Exchange (ETDEWEB)
Dobrowolski, A
2006-04-15
This thesis work is centred on some essential ingredients of a theoretical description of the reaction dynamics of the nuclear fusion and fission process, such as the interaction potential between projectile and target nuclei for fusion and the deformation energy landscape in a multidimensional space for the fission process. We have in particular evaluated the importance of the difference between the neutron and proton density distributions on these 2 processes. The fusion potential between the two interacting nuclei is obtained through the nucleon densities, determined in a self-consistent way through semiclassical density variational calculations for a given effective nucleon-nucleon effective interaction of the Skyrme type. These fusion barriers can then be used in a Langevin formalism to evaluation fusion cross sections. For the fission process it turns out to be essential to allow for the large variety of shapes which appear between the nuclear ground state and the the scission configuration. We show that a shape parametrisation taking into account elongation, as well as possible neck formation, left-right asymmetry and non-axiality allows a precise description of this phenomena in the framework of the macroscopic-microscopic approach. We are thus able to enrich the expression of the liquid-drop type energy through a term which describes the variation of the nuclear energy due to a deformation difference between the proton and neutron distribution. The resulting reduction of the fission barriers is only of the order of one MeV but this can easily cause a change in the fission cross-section by an order of magnitude and thus plays a capital role for the stability of super-heavy of exotic nuclei. (author)
International Nuclear Information System (INIS)
These proceedings of a specialists' meeting on neutron activation cross sections for fission and fusion energy applications are divided into 4 sessions bearing on: - data needs: 4 conferences - experimental work: 11 conferences - theoretical work: 4 conferences - evaluation work: 5 conferences
Frequent fusion and fission of plant mitochondria with unequal nucleoid distribution
Arimura, Shin-ichi; Yamamoto, Junko; Aida, Gen Paul; Nakazono, Mikio; Tsutsumi, Nobuhiro
2004-01-01
The balance between mitochondrial fusion and fission influences the reticular shape of mitochondria in yeasts. Little is known about whether mitochondria fusion occurs in plants. Plant mitochondria are usually more numerous and more grain-shaped than animal mitochondria. blast searches of the nuclear and mitochondrial genome sequences of Arabidopsis thaliana did not find any obvious homologue of mitochondrial fusion genes found in animals and yeasts. To determine whether mitochondrial fusion ...
Uncertainties in fission-product decay-heat calculations
Energy Technology Data Exchange (ETDEWEB)
Oyamatsu, K.; Ohta, H.; Miyazono, T.; Tasaka, K. [Nagoya Univ. (Japan)
1997-03-01
The present precision of the aggregate decay heat calculations is studied quantitatively for 50 fissioning systems. In this evaluation, nuclear data and their uncertainty data are taken from ENDF/B-VI nuclear data library and those which are not available in this library are supplemented by a theoretical consideration. An approximate method is proposed to simplify the evaluation of the uncertainties in the aggregate decay heat calculations so that we can point out easily nuclei which cause large uncertainties in the calculated decay heat values. In this paper, we attempt to clarify the justification of the approximation which was not very clear at the early stage of the study. We find that the aggregate decay heat uncertainties for minor actinides such as Am and Cm isotopes are 3-5 times as large as those for {sup 235}U and {sup 239}Pu. The recommended values by Atomic Energy Society of Japan (AESJ) were given for 3 major fissioning systems, {sup 235}U(t), {sup 239}Pu(t) and {sup 238}U(f). The present results are consistent with the AESJ values for these systems although the two evaluations used different nuclear data libraries and approximations. Therefore, the present results can also be considered to supplement the uncertainty values for the remaining 17 fissioning systems in JNDC2, which were not treated in the AESJ evaluation. Furthermore, we attempt to list nuclear data which cause large uncertainties in decay heat calculations for the future revision of decay and yield data libraries. (author)
A Feasibility Study on a Clean Power Fusion Fission Hybrid Reactor
International Nuclear Information System (INIS)
Full text: In this paper, a design concept of fusion-fission hybrid reactor for the purpose of high level radioactive waste transmutation was investigated. A concept of fusion based trans-uranium isotope (TRU) burner reactor (FTBR) was based on a low power tokamak (150 MW max) and annular ring shaped TRU core with metallic fuel (TRU 60 w/o, Zr 40 w/o) and adjacent fission product (FP) zone. Composition data for TRU and FP are assumed to be the same with those in spent fuel from 1,000 MWe PWR with 10 years decay cooling. Calculation for blanket part were performed using MCNP-X 2.6. Irradiation (burn) cycle was chosen to be 1,100 days (3 years). The power level of TRU core was set to be 2,000 MW and keff at BOC was calculated as 0.97979 and at EOC 0.85049. Calculated TBR value was 1.49 representing a self-sufficiency of fusion fuel. TRU burning was analyzed by calculating TRU mass burned per full power year (MTRU/fpy), support ratio (SR) and percentage of TRU mass burned per year (%TRU/fpy). Same parameters were also used to analyze the FP transmutation. To account for the FP produced in TRU core the net MFP/fpy and net %FP/fpy was also calculated. For toxicity analysis of long lived TRU and FP the percentage reduction of long lived inhalation toxicity (LLIhT) and long lived ingestion toxicity (LLIgT) were also calculated. MTRU/fpy was 747.11 kg with 14.25 MT of initial TRU mass loading, %TRU/fpy was 5.24% and SR was 2.24. FP mass produced in TRU core per fpy was 162.25 kg. LLIhT and LLIgT of TRU's were reduced by 9% and 6% respectively over the burn cycle. FP depletion calculations were performed for two different thicknesses of FP zone 30 cm and 50 cm to evaluate the FP loading effect on FP transmutation performance. TRU transmutation performance of FTBR was also compared with Subcritical Advance Burner Reactor (SABR) design. The comparison showed good TRU transmutation performance of FTBR with a small scaled fusion facility but it still can be improved by
A model for fission-product calculations, 1
International Nuclear Information System (INIS)
Many fission-product cross sections remain unmeasurable thus considerable reliance must be placed upon calculational interpolation and exstrapolation from the few available measured cross sections. The vehicle, particularly for the lighter fission products, is the conventional the optical-statistical model. The applied goals generally are: capture cross sections to 7 - 10 % accuracies and inelastic-scattering cross sections to 25 - 50 %. Comparisons of recent evaluations and experimental results indicate that these goals have too often are far from met, particularly in the area of inelastic scattering, and some of the evaluated fission-product cross sections are simply physically unreasonable. An example of these discrepancies is shown in a figure. The evaluated inelastic-scattering cross sections of palladium are nearly a 100 % discrepant with observation and the isotopes are prominent fission products with large inelastic-scattering cross sections at relatively low energies. It is difficult to avoid the conclusion that the models employed in many of the evaluations are inappropriate and/or inappropriately used. (author)
Fission-fusion and the evolution of hominin social systems.
Grove, Matt; Pearce, Eiluned; Dunbar, R I M
2012-02-01
The course of hominin evolution has involved successive migrations towards higher absolute latitudes over the past three million years. Poorer habitat quality further from the equator has led to the necessity for groups occupying higher latitudes to live at lower population densities. Coupled with a trend towards increasing group size over this time period, this tendency towards expansion has led to exponential increases in the area requirements of hominin groups, and a concomitant need to adjust foraging patterns. The current analyses suggest that the development of increasingly complex, multi-level fission-fusion social systems could have freed hominins of the foraging constraints imposed by large group sizes and low population densities. Analyses of the fossil record suggest latitudinally-driven differences in area requirements of the australopithecines from East and South Africa, and African and Asian Homo erectus. In contrast, chronologically-driven differences appear between H. erectus as a whole and Homo heidelbergensis, and between H. heidelbergensis and the Neanderthals. These results are discussed in relation to studies of the foraging patterns of primates and hunter-gatherers. PMID:22197359
Confidence building in and through fission and fusion activities
International Nuclear Information System (INIS)
The peaceful uses of atomic energy are most suitable for achieving worldwide confidence building for the following reasons. (1) In spite of the need for peaceful uses of nuclear energy, the world is facing difficulties in the public perception and acceptance of nuclear works and facilities. (2) The above difficulties are due to many factors, such as the two sides of nuclear energy peaceful and military, the possibility of a large-scale reactor accident, the lack of understanding about radiation and radioactivity, and finally, emotion and egoism. Some of these factors are unique to nuclear-energy, but in other cases of public reactions, there are many facets similar to the above factors. (3) The public concern about safety is at its highest, broadest and severest point ever, coincident with the highest life expectancy in history. Over-precaution and over-protection about certain things may sometimes spoil one's health. Nuclear energy is most definitely suffering from such a trend. As a result, a severe nuclear accident in any country results in severe damage worldwide no manner in what form the real physical effects reach other countries. (4) The huge science and technology efforts required for fission and fusion activities cannot be fully achieved by one country. Explanations of some of the above factors are given. 2 refs
Neutron cross section calculations for fission-product nuclei
International Nuclear Information System (INIS)
To satisfy nuclear data requirements for fission-product nuclei, Hauser-Feshbach statistical calculations with preequilibrium corrections for neutron-induced reactions on isotopes of Se, Kr, Sr, Zr, Mo, Sn, Xe, and Ba between 0.001 and 20 MeV. Spherical neutron optical parameters were determined by simultaneous fits to resonance data and total cross sections. Isospin coefficients appearing in the optical potentials were determined through analysis of the behavior of s- and p-wave strengths as a function of mass for a given Z. Gamma-ray strength functions, determined through fits to stable-isotope capture data, were used in the calculation of capture cross sections and gamma-ray competition to particle emission. The resulting (n,γ), (n,n'), (n,2n), and (n,3n) cross sections, the secondary neutron emission spectra, and angular distributions calculated for 19 fission products will be averaged to provide a resulting ENDF-type fission-product neutronics file. 11 references
Study on fusion-fission hybrid reactor for transmutation of nuclear waste
International Nuclear Information System (INIS)
A conceptual design of fusion-fission hybrid reactor (FFHR) has been studied for transmutation. The FFHR is magnetic confinement fusion reactor with a blanket containing minor actinides (MAs) from nuclear waste reprocessed from three years cooled spent PWR fuels of 33 GWD/t with initial uranium enrichment of 3.3%. The same plasma conditions as ITER were referred for blanket design. The blanket system consists of MA pebbles coated with Ti nitride, cooling water, structure (F82H) and tritium breeding materials (Li2TiO3). A criticality (keff), Tritium Breeding Ratio (TBR) and energy multiplication (Q value) in the blanket were investigated by the Monte Carlo N-particle transport code MCNP-4C with the nuclear data library JENDL 3.3 after understanding heat calculations. The Q value of 105, fission power 1200 MWt and TBR of 1.8 were obtained at the both conditions of keff value of 0.95 and permissible temperatures in MA, F82H structure, Li2TiO3 and coolant. (author)
On the feasibility of a fusion-fission hybrid reactor driven by dense magnetized plasmas
International Nuclear Information System (INIS)
The feasibility of a fusion-fission hybrid reactor driven by dense magnetized plasmas was analyzed from the point of view of the technical requirements for the fusion and fission components of the reactor. In the conceptual design, a 200 MW hybrid fusion-fission reactor is considered to be used as a heat source for district heating. The fission heat-generating blanket is based on the CANDU reactor technology, while the fusion fast neutrons are provided by a high-density pinch plasma. As far as the fission components of the reactor are concerned, the hybrid reactor turns out to be entirely feasible based on existing technologies. On the other hand extensive development will be needed to meet the requirements for the fusion component of the reactor. The basic conditions for a dense magnetized plasma fusion device to be used for the proposed hybrid concept are not concerned only with the attainment of high neutron yield per pulse (at least 5 x 10 18), but also with a relatively high repetition rate (in the range 1-10 Hz). An important feature of the proposed design is its inherent safety feature: no active component are necessary within the reactor containment area, all the hybrid system control being ensured by the fusion component of the reactor. (authors)
International Nuclear Information System (INIS)
The fusion cross sections and fragment angular distributions for the complete fusion-fission reactions of 11B+238U, 237Np, 12C+237Np, 16O+232Th, 238U, and 19F+23Th at near- and sub-barrier energies have been measured by the fragment folding angle technique. It is revealed that the anomalous anisotropies of fission fragments in latter three systems are existence. Based on the experimental observations and Dressing and Randrup's theory, a new version model of preequilibrium fission is put forward to explain the anomaly. (author)
International Nuclear Information System (INIS)
A parametric study that evaluated the economic performance of breeder/client systems is described. The linkage of the breeders to the clients was modelled using the stockpile approach to determine the system doubling time. Since the actual capital costs of the breeders are uncertain, a precise prediction of the cost of a breeder was not attempted. Instead, the breakeven capital cost of a breeder relative to the capital cost of a client reactor was established by equating the cost of electricity from the breeder/client system to the cost of a system consisting of clients alone. Specific results are presented for two breeder/client systems. The first consisted of an LMFBR with LWR clients. The second consisted of a DT fusion reactor (with a 238U fission suppressed blanket) with LWR clients. The economics of each system was studied as a function of the cost of fissile fuel from a conventional source. Generally, the LMFBR/LWR system achieved relatively small breakeven capital cost ratios; the maximum ratio computed was 2.2 (achieved at approximately triple current conventional fissile material cost). The DTFR/LWR system attained a maximum breakeven capital cost ratio of 4.5 (achieved at the highest plasma quality (ignited device) and triple conventional fissile cost)
The MCEF code for nuclear evaporation and fission calculations
International Nuclear Information System (INIS)
We present an object oriented algorithm, written in the Java programming language, which performs a Monte Carlo calculation of the evaporation-fission process taking place inside an excited nucleus. We show that this nuclear physics problem is very suited for the object oriented programming by constructing two simple objects: one that handles all nuclear properties and another that takes care of the nuclear reaction. The MCEF code was used to calculate important results for nuclear reactions, and here we show examples of possible uses for this code. (author)
Clement, J. D.
1973-01-01
Different types of nuclear fission reactors and fissionable materials are compared. Special emphasis is placed upon the environmental impact of such reactors. Graphs and charts comparing reactor facilities in the U. S. are presented.
The present computational methods for fusion and fusion-fission hybrid nucleonics studies at EIR
International Nuclear Information System (INIS)
The preparation of adequate nuclear data libraries based on the NJOY cross section system is described with respect to the fusion and fusion-fission blanket studies. Three main computational schemes to prepare the cross section data sets are available at EIR at the present moment. The first method is based on the 'bondarenko' or 'background cross section' interpolation scheme for resonance shielding which is adequate for fast reactors as well as for fusion applications. The energy groupwise cross sections are processed for many background cross sections, stored into a MATXS file and then interpolated with the TRANSX-CTR module, which generates suitable formats for most transport codes. The second model is more sophisticated since the correct resonance spectrum is computed from the slowing down equations. This method allows one to consider properly the resonance overlap in the case of single resonance material as well as for mixtures related to a given geometry. The new NJOY editing module MICROR is used to produce cross section library tapes for the resonance-cell code MICROX-2. MICROX-2 then performs the geometry dependent pointwise self-shielding of resonance cross sections and delivers suitable collapsed cross sections. (Auth.)
Fission-suppressed fusion breeder on the thorium cycle and nonproliferation
Moir, R. W.
2012-06-01
Fusion reactors could be designed to breed fissile material while suppressing fissioning thereby enhancing safety. The produced fuel could be used to startup and makeup fuel for fission reactors. Each fusion reaction can produce typically 0.6 fissile atoms and release about 1.6 times the 14 MeV neutron's energy in the blanket in the fission-suppressed design. This production rate is 2660 kg/1000 MW of fusion power for a year. The revenues would be doubled from such a plant by selling fuel at a price of 60/g and electricity at 0.05/kWh for Q=Pfusion/Pinput=4. Fusion reactors could be designed to destroy fission wastes by transmutation and fissioning but this is not a natural use of fusion whereas it is a designed use of fission reactors. Fusion could supply makeup fuel to fission reactors that were dedicated to fissioning wastes with some of their neutrons. The design for safety and heat removal and other items is already accomplished with fission reactors. Whereas fusion reactors have geometry that compromises safety with a complex and thin wall separating the fusion zone from the blanket zone where wastes could be destroyed. Nonproliferation can be enhanced by mixing 233U with 238U. Also nonproliferation is enhanced in typical fission-suppressed designs by generating up to 0.05 232U atoms for each 233U atom produced from thorium, about twice the IAEA standards of "reduced protection" or "self protection." With 2.4% 232U, high explosive material is predicted to degrade owing to ionizing radiation after a little over 1/2 year and the heat rate is 77 W just after separation and climbs to over 600 W ten years later. The fissile material can be used to fuel most any fission reactor but is especially appropriate for molten salt reactors (MSR) also called liquid fluoride thorium reactors (LFTR) because of the molten fuel does not need hands on fabrication and handling.
Progress on the conceptual design of a mirror hybrid fusion--fission reactor
International Nuclear Information System (INIS)
A conceptual design study was made of a fusion-fission reactor for the purpose of producing fissile material and electricity. The fusion component is a D-T plasma confined by a pair of magnetic mirror coils in a Yin-Yang configuration and is sustained by neutral beam injection. The neutrons from the fusion plasma drive the fission assembly which is composed of natural uranium carbide fuel rods clad with stainless steel and helium cooled. It was shown conceptually how the reactor might be built using essentially present-day technology and how the uranium-bearing blanket modules can be routinely changed to allow separation of the bred fissile fuel
Allowance for the tunnel effect in the entrance channel of fusion-fission reactions
Litnevsky, V. L.; Kosenko, G. I.; Ivanyuk, F. A.
2016-05-01
A two-stage model is developed in order to describe fusion-fission reactions. The process in the course of which colliding ions approach each other is simulated at the first stage, the deformations and relative orientations of the ions being taken into account. The first stage of the calculation is completed as soon as colliding nuclei touch each other. A continuous nuclear system (monosystem) is formed at this instant. The emerging distributions of the angular momenta of this system and of its potential and internal energies at the point of touching are used as input data that are necessary for triggering the second stage of the calculation. The evolution of collective coordinates that describe the shape of the monosystem is calculated at the second stage. The description of this evolution is terminated either at the instant of its fission or upon the release of a major part of its excess energy via particle and photon emission. In the latter case, the probability for the fission of the monosystem or a further decrease in its excitation energy becomes extremely small. The ion-collision process and the evolution of the monosystem formed after primary nuclei come into contact are simulated on the basis of stochastic Langevin equations. The quantities appearing in them (which include the potential energy and inertial and friction parameters) are determined with allowance for the shell structure of nuclei. The tunneling of colliding nuclei through the Coulomb barrier is taken into account, and the effect of this phenomenon on model predictions is studied.
Dynamical calculations of nuclear fission and heavy-ion reactions
International Nuclear Information System (INIS)
With the goal of determining the magnitude and mechanism of nuclear dissipation from comparisons of predictions with experimental data, we describe recent calculations in a unified macroscopic-microscopic approach to large-amplitude collective nuclear motion such as occurs in fission and heavy-ion reactions. We describe the time dependence of the distribution function in phase space of collective coordinates and momenta by a generalized Fokker-Planck equation. The nuclear potential energy of deformation is calculated as the sum of repulsive Coulomb and centrifugal energies and an attractive Yukawa-plus-exponential potential, the inertia tensor is calculated for a superposition of rigid-body rotation and incompressible, nearly irrotational flow by use of the Werner-Wheeler method, and the dissipation ensor that describes the conversion of collective energy into single-particle excitation energy is calculated for two prototype mechanisms that represent opposite extremes of large and small dissipation. We solve the generalized Hamilton equations of motion for the first moments of the distribution function to obtain the mean translational fission-fragment kinetic energy and mass of a third fragment that sometimes forms between the two end fragments, as well as dynamical thresholds, capture cross sections, and ternary events in heavy-ion reactions. 33 references
Deceleration of fusion-fission cycles improves mitochondrial quality control during aging.
Directory of Open Access Journals (Sweden)
Marc Thilo Figge
Full Text Available Mitochondrial dynamics and mitophagy play a key role in ensuring mitochondrial quality control. Impairment thereof was proposed to be causative to neurodegenerative diseases, diabetes, and cancer. Accumulation of mitochondrial dysfunction was further linked to aging. Here we applied a probabilistic modeling approach integrating our current knowledge on mitochondrial biology allowing us to simulate mitochondrial function and quality control during aging in silico. We demonstrate that cycles of fusion and fission and mitophagy indeed are essential for ensuring a high average quality of mitochondria, even under conditions in which random molecular damage is present. Prompted by earlier observations that mitochondrial fission itself can cause a partial drop in mitochondrial membrane potential, we tested the consequences of mitochondrial dynamics being harmful on its own. Next to directly impairing mitochondrial function, pre-existing molecular damage may be propagated and enhanced across the mitochondrial population by content mixing. In this situation, such an infection-like phenomenon impairs mitochondrial quality control progressively. However, when imposing an age-dependent deceleration of cycles of fusion and fission, we observe a delay in the loss of average quality of mitochondria. This provides a rational why fusion and fission rates are reduced during aging and why loss of a mitochondrial fission factor can extend life span in fungi. We propose the 'mitochondrial infectious damage adaptation' (MIDA model according to which a deceleration of fusion-fission cycles reflects a systemic adaptation increasing life span.
Feasibility of recycling thorium in a fusion-fission hybrid/PWR symbiotic system
Energy Technology Data Exchange (ETDEWEB)
Josephs, J. M.
1980-12-31
A study was made of the economic impact of high levels of radioactivity in the thorium fuel cycle. The sources of this radioactivity and means of calculating the radioactive levels at various stages in the fuel cycle are discussed and estimates of expected levels are given. The feasibility of various methods of recycling thorium is discussed. These methods include direct recycle, recycle after storage for 14 years to allow radioactivity to decrease, shortening irradiation times to limit radioactivity build up, and the use of the window in time immediately after reprocessing where radioactivity levels are diminished. An economic comparison is made for the first two methods together with the throwaway option where thorium is not recycled using a mass energy flow model developed for a CTHR (Commercial Tokamak Hybrid Reactor), a fusion-fission hybrid reactor which serves as fuel producer for several PWR reactors.
Feasibility of recycling thorium in a fusion-fission hybrid/PWR symbiotic system
International Nuclear Information System (INIS)
A study was made of the economic impact of high levels of radioactivity in the thorium fuel cycle. The sources of this radioactivity and means of calculating the radioactive levels at various stages in the fuel cycle are discussed and estimates of expected levels are given. The feasibility of various methods of recycling thorium is discussed. These methods include direct recycle, recycle after storage for 14 years to allow radioactivity to decrease, shortening irradiation times to limit radioactivity build up, and the use of the window in time immediately after reprocessing where radioactivity levels are diminished. An economic comparison is made for the first two methods together with the throwaway option where thorium is not recycled using a mass energy flow model developed for a CTHR (Commercial Tokamak Hybrid Reactor), a fusion-fission hybrid reactor which serves as fuel producer for several PWR reactors
Study of near-stability nuclei populated as fission fragments in heavy-ion fusion reactions
International Nuclear Information System (INIS)
Examples are presented to illustrate the power of prompt γ-ray spectroscopy of fission fragments from compound nuclei with A ∼ 200 formed in fusion-evaporation reactions in experiments using the Gammasphere Ge-detector array. Complementary methods, such as Coulomb excitation and deep-inelastic processes, are also discussed. In other cases (n, xnγ) reactions on stable isotopes have been used to establish neutron excitation functions for γ-rays using a pulsed 'white'-neutron source, coupled to a high-energy-resolution germanium-detector array. The excitation functions can unambiguously assign γ-rays to a specific reaction product. Results from all these methods bridge the gaps in the systematics of high-spin states between the neutron-deficient and neutron-rich nuclei. Results near shell closures should motivate new shell model calculations.
Benchmark calculations for fusion blanket development
International Nuclear Information System (INIS)
Benchmark problems representing the leading fusion blanket concepts are presented. Benchmark calculations for self-cooled Li17Pb83 and helium-cooled blankets were performed. Multigroup data libraries generated from ENDF/B-IV and V files using the NJOY and AMPX processing codes with different weighting functions were used. The sensitivity of the tritium breeding ratio to group structure and weighting spectrum increases as the thickness and Li enrichment decrease with up to 20% discrepancies for thin natural Li17Pb83 blankets. (author)
Nuclear irradiation parameters of beryllium under fusion, fission and IFMIF irradiation conditions
International Nuclear Information System (INIS)
A computational analysis is presented of the nuclear irradiation parameters for Beryllium under irradiation in typical neutron environments of fission and fusion reactors, and of the presently designed intense fusion neutron source IFMIF. The analysis shows that dpa and Tritium production rates at fusion relevant levels can be achieved with existing high flux fission reactors while the achievable Helium production is too low. The resulting He-Tritium and He/dpa ratios do not meet typical fusion irradiation conditions. Irradiation simulations in the medium flux test modules of the IFMIF neutron source facility were shown to be more suitable to match fusion typical irradiation conditions. To achieve sufficiently high production rates it is suggested to remove the creep-fatigue testing machine together with the W spectra shifter plate and move the tritium release module upstream towards the high flux test module. (author)
A 39 neutron group self-shielded cross section library for the Lotus fusion-fission test facility
International Nuclear Information System (INIS)
A 39 neutron group cross section library for fusion fission blanket calculations and especially for the analysis of the LOTUS experiment has been processed using the NJOY system. The library has been generated mostly using the ENDF/B-IV basic files at 296 K. All cross sections were self-shielded using the Bondarenko method. 5 background cross sections, namely 1010, 104, 102, 10 and 1 barns respectively were considered. The tabulated dilution dependent cross sections have been interpolated with the code TRANSX-CTR which is adequate for fusion applications. The fission spectrum of the fissionable material thorium has been collapsed from the fission matrices using the Bondarenko weighting scheme. The correct geometry of the LOTUS blanket and the cell specifications were correctly considered in the interpolation scheme. Some reaction cross sections for dosimetry applications have been included into the library. These base on the more recent ENDF/B-V evaluation. Transport and response edit cross sections have been coupled in the usual way to form P0 - P3 card image tables. Furthermore they have been converted into a binary file suitable to our RSYST computational system. Moreover the cross section card image tables have been reformatted and fitted into a BXSLIB binary library for the LANL-ONEDANT transport module. (Auth.)
International Nuclear Information System (INIS)
Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from a LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with each other or a target block in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., 137Cs, 90Sr, 129I, 99Tc, etc. The 14-MeV fusion neutrons released during the pellet burn cause transmutation reactions (e.g., (n,2n), (n,α), (n,γ), etc.) that convert the long-lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product. The transmutation parametric studies conclude that the design of the hypervelocity projectiles should emphasize the achievement of high densities in the transmutation regions (greater than the DT fusion fuel density), as well as the DT ignition and burn criterion (rho R = 1.0 to 3.0) requirements. These studies also indicate that masses on the order of 1.0 g at densities of rho greater than or equal to 500.0 g/cm3 are required for a practical fusion-based fission product transmutation system
Model Calculation of Fission Product Yields Data using GEF Code
International Nuclear Information System (INIS)
Fission yields data are classified with spontaneous fission data and neutron induced fission data. The fission product yields data at several energy points for the limited actinides are included in nuclear data libraries such as ENDF/B, JEFF and JENDL because production of those is based mainly on experimental results and it is very difficult to conduct experiments for all actinides and continuous energies. Therefore, in order to obtain fission yields data without experimental data, a theoretical fission model should be introduced to produce the yields data. GEneral Fission model (GEF) is developed to predict the properties for fissioning systems that have not been measured and that are not accessible to experiment. In this study, the fission yields data generated from GEF code are compared with the measured data and the recently available nuclear data libraries. The GEF code is very powerful tool to generate fission yields without measurements. Also, it can produce the distribution of fission product yields for continuous neutron energy while measured data are given only at several energies. The fission yields data of 235U have been tentatively generated with GEF code in this work. Comparing GEF results with measurements and recently released evaluated fission yields data, it is confirmed that GEF code can successfully predict the fission yields data. With its sophisticated model, GEF code is playing a significant role in nuclear industry
Analysis of primary damage in silicon carbide under fusion and fission neutron spectra
Guo, Daxi; Zang, Hang; Zhang, Peng; Xi, Jianqi; Li, Tao; Ma, Li; He, Chaohui
2014-12-01
Irradiation parameters on primary damage states of SiC are evaluated and compared for the first wall of ITER under deuterium-deuterium (DD) and deuterium-tritium (DT) operation, the high temperature gas-cooled reactor (HTGR) and high flux isotope reactor (HFIR). With the same neutron fluence, the studied fusion spectra produce more damage and much higher gas production than the fission spectra. Due to comparable gas production and similar weighted primary recoil spectra, HFIR is considered suitable to simulate the neutron irradiation in an HTGR. In contrast to the significant differences between the weighted primary recoil spectra of the fission and the fusion spectra, the weighted secondary recoil spectra of HFIR and HTGR match those of DD and DT, indicating that displacement cascades by the fission and the fusion irradiation are similar when the damage distribution among damaged regions by secondary recoils is taken into account.
Analysis of primary damage in silicon carbide under fusion and fission neutron spectra
Energy Technology Data Exchange (ETDEWEB)
Guo, Daxi; Zang, Hang; Zhang, Peng; Xi, Jianqi; Li, Tao; Ma, Li; He, Chaohui, E-mail: hechaohui@mail.xjtu.edu.cn
2014-12-15
Irradiation parameters on primary damage states of SiC are evaluated and compared for the first wall of ITER under deuterium–deuterium (DD) and deuterium–tritium (DT) operation, the high temperature gas-cooled reactor (HTGR) and high flux isotope reactor (HFIR). With the same neutron fluence, the studied fusion spectra produce more damage and much higher gas production than the fission spectra. Due to comparable gas production and similar weighted primary recoil spectra, HFIR is considered suitable to simulate the neutron irradiation in an HTGR. In contrast to the significant differences between the weighted primary recoil spectra of the fission and the fusion spectra, the weighted secondary recoil spectra of HFIR and HTGR match those of DD and DT, indicating that displacement cascades by the fission and the fusion irradiation are similar when the damage distribution among damaged regions by secondary recoils is taken into account.
International Nuclear Information System (INIS)
Limitations of the fission fuel resources will presumably mandate the replacement of thermal fission reactors by fast fission reactors that operate on a self-sufficient closed fuel cycle. This replacement might take place within the next one hundred years, so the direct competitors of fusion reactors will be fission reactors of the latter rather than the former type. Also, fast fission reactors, in contrast to thermal fission reactors, have the potential for transmuting long-lived actinides into short-lived fission products. The associated reduction of the long-term activation of radioactive waste due to actinides makes the comparison of radioactive waste from fast fission reactors to that from fusion reactors more rewarding than the comparison of radioactive waste from thermal fission reactors to that from fusion reactors. Radioactive waste from an experimental and a commercial fast fission reactor and an experimental and a commercial fusion reactor has been characterized. The fast fission reactors chosen for this study were the Experimental Breeder Reactor 2 and the Integral Fast Reactor. The fusion reactors chosen for this study were the International Thermonuclear Experimental Reactor and a Reduced Activation Ferrite Helium Tokamak. The comparison of radioactive waste parameters shows that radioactive waste from the experimental fast fission reactor may be less hazardous than that from the experimental fusion reactor. Inclusion of the actinides would reverse this conclusion only in the long-term. Radioactive waste from the commercial fusion reactor may always be less hazardous than that from the commercial fast fission reactor, irrespective of the inclusion or exclusion of the actinides. The fusion waste would even be far less hazardous, if advanced structural materials, like silicon carbide or vanadium alloy, were employed
Fusion-Fission Research Facility (FFRF) as a Practical Step Toward Hybrid
International Nuclear Information System (INIS)
The project of ASIPP (with PPPL participation), called FFRF, (R/a=4/1 m/m, Ipl=5 MA, Btor=4-6 T, PDT=50-100 MW, Pfission=80-4000 MW, 1 m thick blanket) is outlined. FFRF stands for the Fusion-Fission Research Facility with a unique fusion mission and a pioneering mission of merging fusion and fission for accumulation of design, experimental, and operational data for future hybrid applications. The design of FFRF will use as much as possible the EAST and ITER design experience. On the other hand, FFRF strongly relies on new, Lithium Wall Fusion plasma regimes, the development of which has already started in the US and China.
Fusion-Fission Research Facility (FFRF) as a Practical Step Toward Hybrids
Energy Technology Data Exchange (ETDEWEB)
L. Zakharov, J. Li and Y. Wu
2010-11-18
The project of ASIPP (with PPPL participation), called FFRF, (R/a=4/1 m/m, Ipl=5 MA, Btor=4-6 T, PDT=50-100 MW, Pfission=80-4000 MW, 1 m thick blanket) is outlined. FFRF stands for the Fusion-Fission Research Facility with a unique fusion mission and a pioneering mission of merging fusion and fission for accumulation of design, experimental, and operational data for future hybrid applications. The design of FFRF will use as much as possible the EAST and ITER design experience. On the other hand, FFRF strongly relies on new, Lithium Wall Fusion plasma regimes, the development of which has already started in the US and China.
International Nuclear Information System (INIS)
An improved calculation is presented for the prompt fission neutron spectrum N(E) from the spontaneous fission of /sup 252/Cf. In this calculation the fission-spectrum model of Madland and Nix is used, but with several improvements leading to a physically more accurate representation of the spectrum. Specifically, the contributions to N(E) from the entire fission-fragment mass and charge distributions will be calculated instead of calculating on the basis of a seven- point approximation to the peaks of these distributions as has been done in the past. Therefore, values of the energy release in fission, fission-fragment kinetic energy, and compound nucleus cross section for the inverse process will be considered on a point-by-point basis over the fragment yield distributions instead of considering averages of these quantities over the peaks of the distributions. Preliminary results will be presented and compared with a measurement, an earlier calculation, and a recent evaluation of the spectrum. 14 refs., 4 figs
Isotopic fission fragment distributions as a deep probe to fusion-fission dynamics
Farget, F.; Caamano, M.; Delaune, O.; Tarasov, O.B.; Derkx, X.; Schmidt, K. -H.; Amthor, A.M.; Audouin, L.; Bacri, C.-O.; Barreau, G.; Bastin, B.; Bazin, D.; Blank, B.; Benlliure, J.; Caceres, L.
2012-01-01
During the fission process, the nucleus deforms and elongates up to the two fragments inception and their final separation at scission deformation. The evolution of the nucleus energy with deformation is determined by the macroscopic properties of the nucleus, and is also strongly influenced by the single-particle structure of the nucleus. The fission fragment distribution is a direct consequence of the deformation path the nucleus has encountered, and therefore is the most genuine experiment...
Fusion-fission probabilities, cross sections and structure notes of super-heavy nuclei
Kowal, Michał; Cap, Tomasz; Jachimowicz, Piotr; Skalski, Janusz; Siwek-Wilczyńska, Krystyna; Wilczyński, Janusz
2016-01-01
Fusion - fission probabilities in the synthesis of heaviest elements are discussed in the context of the latest experimental reports. Cross sections for superheavy nuclei are evaluated using "Fusion by Diffusion" (FBD) model. Predictive power of this approach is shown for experimentally known Lv, Og isotopes and predictions given for Z=119,120. Ground state and saddle point properties as: masses, shell corrections, pairing energies and deformations necessary for cross section estimations are ...
Description of the Fusion-Fission Reactions in the Framework of Dinuclear System Conception
Kalandarov, Sh. A.; Adamian, G. G.; Antonenko, N. V.; Wieleczko, J. P.
2016-05-01
Within the dinuclear system model fusion-fission reactions 78Kr+40Ca and 86Kr+48Ca is investigated. The charge distributions of the decay products are predicted at bombarding energy 10 MeV/nucleon. The competition is treated between complete fusion followed by the decay of compound nucleus and quasifission channels. The possible explanation of the odd-even staggering in the yield of the final reaction products at high excitation energies is discussed.
Description of the Fusion-Fission Reactions in the Framework of Dinuclear System Conception
Directory of Open Access Journals (Sweden)
Kalandarov Sh. A.
2016-01-01
Full Text Available Within the dinuclear system model fusion-fission reactions 78Kr+40Ca and 86Kr+48Ca is investigated. The charge distributions of the decay products are predicted at bombarding energy 10 MeV/nucleon. The competition is treated between complete fusion followed by the decay of compound nucleus and quasifission channels. The possible explanation of the odd-even staggering in the yield of the final reaction products at high excitation energies is discussed.
Molecular dynamics simulations of cluster fission and fusion processes
DEFF Research Database (Denmark)
Lyalin, Andrey G.; Obolensky, Oleg I.; Solov'yov, Ilia;
2004-01-01
groups of atoms from the parent cluster is largely independent of the isomer form of the parent cluster. The importance of rearrangement of the cluster structure during the fission process is elucidated. This rearrangement may include transition to another isomer state of the parent cluster before actual......Results of molecular dynamics simulations of fission reactions Na_10^2+ --> Na_7^+ +Na_3^+ and Na_18^2+ --> 2Na_9^+ are presented. The dependence of the fission barriers on the isomer structure of the parent cluster is analyzed. It is demonstrated that the energy necessary for removing homothetic...... separation of the daughter fragments begins and/or forming a "neck" between the separating fragments. A novel algorithm for modeling the cluster growth process is described. This approach is based on dynamic search for the most stable cluster isomers and allows one to find the optimized cluster geometries...
International Nuclear Information System (INIS)
A multigroup library HENDL2.1/SS (Hybrid Evaluated Nuclear Data Library/Self-Shielding) based on ENDF/B-VII.0 evaluate data has been generated using Bondarenko and flux calculator method for the correction of self-shielding effect of neutronics analyses. To validate the reliability of the multigroup library HENDL2.1/SS, transport calculations for fusion-fission hybrid system FDS-I were performed in this paper. It was verified that the calculations with the HENDL2.1/SS gave almost the same results with MCNP calculations and were better than calculations with the HENDL2.0/MG which is another multigroup library without self-shielding correction. The test results also showed that neglecting resonance self-shielding caused underestimation of the Keff, neutron fluxes and waste transmutation ratios in the multigroup calculations of FDS-I.
Energy Technology Data Exchange (ETDEWEB)
Zou Jun, E-mail: jzou@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230027 (China); He Zhaozhong; Zeng Qin; Qiu Yuefeng; Wang Minghuang [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230027 (China)
2010-12-15
A multigroup library HENDL2.1/SS (Hybrid Evaluated Nuclear Data Library/Self-Shielding) based on ENDF/B-VII.0 evaluate data has been generated using Bondarenko and flux calculator method for the correction of self-shielding effect of neutronics analyses. To validate the reliability of the multigroup library HENDL2.1/SS, transport calculations for fusion-fission hybrid system FDS-I were performed in this paper. It was verified that the calculations with the HENDL2.1/SS gave almost the same results with MCNP calculations and were better than calculations with the HENDL2.0/MG which is another multigroup library without self-shielding correction. The test results also showed that neglecting resonance self-shielding caused underestimation of the K{sub eff}, neutron fluxes and waste transmutation ratios in the multigroup calculations of FDS-I.
Prokhorova, E. V.; Bogachev, A. A.; Itkis, M. G.; Itkis, I. M.; Knyazheva, G. N.; Kondratiev, N. A.; Kozulin, E. M.; Krupa, L.; Oganessian, Yu. Ts.; Pokrovsky, I. V.; Pashkevich, V. V.; Rusanov, A. Ya.
2008-04-01
Mass-energy distributions (MEDs) and capture-fission cross sections have been measured in the reaction 48Ca + 208Pb → 256No at the energies E=206-242 MeV using a double-arm time-of-flight spectrometer CORSET. It has been observed that MED of the fragments consists of two parts, namely, the classical fusion-fission process corresponding to the symmetric fission of 256No and quasi-fission "shoulders" corresponding to the light fragment masses ˜60-90 u and complimentary heavy fragment masses. The quasi-fission "shoulders" have a higher total kinetic energy (TKE) as compared with that expected for the classical fission. A mathematical formalism was employed for the MEDs fragment decomposition into fusion-fission and quasi-fission components. In the fusion-fission process a high-energy Super-Short mode has been discovered for the masses M=130-135 u and the TKE of ≈233 MeV.
International Nuclear Information System (INIS)
Mass-energy distributions (MEDs) and capture-fission cross sections have been measured in the reaction 48Ca + 208Pb →256No at the energies Elab=206-242 MeV using a double-arm time-of-flight spectrometer CORSET. It has been observed that MED of the fragments consists of two parts, namely, the classical fusion-fission process corresponding to the symmetric fission of 256No and quasi-fission 'shoulders' corresponding to the light fragment masses ∼60-90 u and complimentary heavy fragment masses. The quasi-fission 'shoulders' have a higher total kinetic energy (TKE) as compared with that expected for the classical fission. A mathematical formalism was employed for the MEDs fragment decomposition into fusion-fission and quasi-fission components. In the fusion-fission process a high-energy Super-Short mode has been discovered for the masses MH=130-135 u and the TKE of ∼233 MeV
Fusability and fissionability in 86Kr induced reactions near and below the fusion barrier
International Nuclear Information System (INIS)
Evaporation-residue excitation functions for the reactions 86Kr + sup(70,76)Ge, sup(92,100)Mo, sup(99,102,104)Ru have been measured using activation methods and the velocity filter SHIP. The data span the region from well below the fusion barrier up to and beyond the energy where limitation by fission competition takes place. The data are shown to be compatible with the concept of complete fusion followed by the statistical decay of the equilibrated compound nucleus. Information on both the fusion probability at and below the fusion threshold and the fissionability of the compound nuclei formed is extracted. The model dependence of the extracted fission barriers is discussed in detail. In analogy to studies involving lighter projectiles, strong correlations between the low-energy nuclear-structure properties of the nuclei and the subbarrier fusion probability are found. A relative shift of the fusion barrier to higher energies, that increases with the number of valence neutrons in the target nuclei, is observed. (orig.)
Soliton Fission and Fusion in (2+1)-Dimensional Boiti-Leon-Pempinelli System
Institute of Scientific and Technical Information of China (English)
ZHENG Chun-Long; FANG Jian-Ping; CHEN Li-Qun
2005-01-01
By means of a special Painlevé-Backlund transformation and a multilinear variable separation approach,an exact solution with arbitrary functions of the (2+1)-dimensional Boiti-Leon-Pempinelli system (BLP) is derived.Based on the derived variable separation solution, we obtain some special soliton fission and fusion solutions for the higher dimensional BLP system.
Short-Term Forecasting of Taiwanese Earthquakes Using a Universal Model of Fusion-Fission Processes
S.A. Cheong; T.L. Tan; C.-C. Chen; W.-L. Chang; Z. Liu; L.Y. Chew; P.M.A. Sloot; N.F. Johnson
2014-01-01
Predicting how large an earthquake can be, where and when it will strike remains an elusive goal in spite of the ever-increasing volume of data collected by earth scientists. In this paper, we introduce a universal model of fusion-fission processes that can be used to predict earthquakes starting fr
Workshop summaries for the third US/USSR symposium on fusion-fission reactors
International Nuclear Information System (INIS)
Workshop summaries on topics related to the near-term development requirements for fusion-fission (hybrid) reactors are presented. The summary topics are as follows: (1) external factors, (2) plasma engineering, (3) ICF hybrid reactors, (4) blanket design, (5) materials and tritium, and (6) blanket engineering development requirements
Fission barriers of super-heavy nuclei produced in cold-fusion reactions
Energy Technology Data Exchange (ETDEWEB)
Peter, J. [LPC Caen, ENSICAEN, Caen cedex (France)
2004-11-01
Excitation functions of super-heavy evaporation residues formed in cold-fusion reactions were analyzed with the aim of getting information on the fission barrier height of these nuclei. The method uses the location of the maximum of 1n and 2n excitation functions. The results obtained on nuclei from Z=104 to 112 are compared to three theoretical predictions. (orig.)
Workshop summaries for the third US/USSR symposium on fusion-fission reactors
Energy Technology Data Exchange (ETDEWEB)
Jassby, D.L. (ed.)
1979-07-01
Workshop summaries on topics related to the near-term development requirements for fusion-fission (hybrid) reactors are presented. The summary topics are as follows: (1) external factors, (2) plasma engineering, (3) ICF hybrid reactors, (4) blanket design, (5) materials and tritium, and (6) blanket engineering development requirements. (MOW)
Fusion-fission-light ion correlation of mechanical property change in a TZM alloy
International Nuclear Information System (INIS)
In order to study the correlation of damage among fusion neutron-fission neutron-light ion irradiation at low fluence levels, mechanical properties and microstructures in a molybdenum alloy, stress-relieved TZM, were studied. Miniature tensile specimens and TEM disks were irradiated to fluences of 10-4-10-2 dpa by 14 MeV neutrons at RTNS-II, by fission neutrons at Kyoto University Reactor and by 16 MeV Dueterons at Tohoku University Cyclotron. Irradiation hardening was observed at all irradiation conditions. The ratio of the increase in yield stress at the fluence of 1x1022/m2 was 4:3:2 for 6 MeV deuterons, fusion neutron and fission neutron, respectively. The magnitude of irradiation hardening was not expressed by the same curve even in the dpa scale. Small defect clusters were observed uniformly in specimens irradiated with any particles. (orig.)
Microscopic Calculation of Fusion: Light to Heavy Systems
Umar, A S; Maruhn, J A; Keser, R
2013-01-01
The density-constrained time-dependent Hartree-Fock (DC-TDHF) theory is a fully microscopic approach for calculating heavy-ion interaction potentials and fusion cross sections below and above the fusion barrier. We discuss recent applications of DC-TDHF method to fusion of light and heavy neutron-rich systems.
Veselsky, M.
2003-01-01
The mechanism of fusion hindrance, an effect observed in the reactions of cold, warm and hot fusion leading to production of the superheavy elements, is investigated. A systematics of transfermium production cross sections is used to determine fusion probabilities. Mechanism of fusion hindrance is described as a competition of fusion and quasi-fission. Available evaporation residue cross sections in the superheavy region are reproduced satisfactorily. Analysis of the measured capture cross se...
FISPRO: a simplified computer program for general fission product formation and decay calculations
International Nuclear Information System (INIS)
This report describes a computer program that solves a general form of the fission product formation and decay equations over given time steps for arbitrary decay chains composed of up to three nuclides. All fission product data and operational history data are input through user-defined input files. The program is very useful in the calculation of fission product activities of specific nuclides for various reactor operational histories and accident consequence calculations
International Nuclear Information System (INIS)
Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from an LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with each other or a target block in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., 137Cs, 90Sr, 129I, 99Tc, etc. The 14-MeV fusion neutrons released during the pellet burn cause transmutation reactions (e.g., (n,2n), (n,α), (n,γ), etc.) that convert the long-lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product. The transmutation parametric studies conclude that the design of the hypervelocity projectiles should emphasize the achievement of high densities in the transmutation regions (greater than the DT fusion fuel density), as well as the DT ignition and burn criterion (rho R=1.0 to 3.0) requirements
Fusion and quasi-fission dynamics in nearly-symmetric reactions
Wang, Ning; Li, Zhuxia
2015-01-01
Some nearly-symmetric fusion reactions are systematically investigated with the improved quantum molecular dynamics (ImQMD) model. By introducing two-body inelastic scattering in the Fermi constraint procedure, the stability of an individual nucleus and the description of fusion cross sections at energies near the Coulomb barrier can be further improved. Simultaneously, the quasi-fission process in $^{154}$Sm+$^{160}$Gd is also investigated with the microscopic dynamics model for the first time. We find that at energies above the Bass barrier, the fusion probability is smaller than $10^{-5}$ for this reaction, and the nuclear contact-time is generally smaller than $1500$ fm/c. From the central collisions of Sm+Gd, the neutron-rich fragments such as $^{164,165}$Gd, $^{192}$W can be produced in the ImQMD simulations, which implies that the quasi-fission reaction could be an alternative way to synthesize new neutron-rich heavy nuclei.
Major features of a mirror fusion--fast fission hybrid reactor
International Nuclear Information System (INIS)
A conceptual design was made of a fusion-fission reactor. The fusion component is a D-T plasma confined by a pair of magnetic mirror coils in a Yin-Yang configuration and sustained by hot neutral beam injection. The neutrons from the fusion plasma drive the fission assembly which is composed of natural uranium carbide fuel rods clad with stainless steel and is cooled by helium. It was shown how the reactor can be built using essentially present day construction technology and how the uranium bearing blanket modules can be routinely changed to allow separation of the bred fissile fuel of which approximately 1200 kg of plutonium are produced each year along with the approximately 750 MW of electricity. (U.S.)
International Nuclear Information System (INIS)
This paper considers nuclear breeding systems (i.e., production of fissile fuel from fertile materials). The range of breeding technologies considered is deliberately wide. We include systems which breed by using internal neutron sources--a reactor-breeder, exemplified by the liquid metal fast breeder reactor (LMFBR)--and systems which breed by using external neutron sources--exemplified in this paper primarily by hybrid fusion-fission breeders
Dissipation strength of the tilting degree of freedom in fusion-fission reactions
Nadtochy, P. N.; Vanin, D. V.; Cheredov, A. V.; Fedorov, S. V.; Ryabov, E. G.; Adeev, G. D.
2016-05-01
The four-dimensional Langevin model was applied to calculate a wide set of experimental observables for compound nuclei, formed in heavy-ion fusion-fission reactions. A modified one-body mechanism for nuclear dissipation with a reduction coefficient ks of the contribution from a "wall" formula was used for shapes parameters. Different possibilities of deformation-dependent dissipation coefficient for the K coordinate (γK) were investigated. Presented results demonstrate that the influence of the ks and γK parameters on the calculated quantities can be selectively probed. It was found that it is possible to describe experimental data with the deformation-dependent γK coefficient. One of the possibility is to use large values of γK ≃ 0.2 (MeV zs)-1/2 for compact shapes featuring no neck and small values of γK ≃ 0.0077 (MeV zs)-1/2 for elongated shapes.
Directory of Open Access Journals (Sweden)
Kaplan Abdullah
2015-01-01
Full Text Available Implementation of projects of new generation nuclear power plants requires the solving of material science and technological issues in developing of reactor materials. Melts of heavy metals (Pb, Bi and Pb-Bi due to their nuclear and thermophysical properties, are the candidate coolants for fast reactors and accelerator-driven systems (ADS. In this study, α, γ, p, n and 3He induced fission cross section calculations for 209Bi target nucleus at high-energy regions for (α,f, (γ,f, (p,f, (n,f and (3He,f reactions have been investigated using different fission reaction models. Mamdouh Table, Sierk, Rotating Liquid Drop and Fission Path models of theoretical fission barriers of TALYS 1.6 code have been used for the fission cross section calculations. The calculated results have been compared with the experimental data taken from the EXFOR database. TALYS 1.6 Sierk model calculations exhibit generally good agreement with the experimental measurements for all reactions used in this study.
Liquid metal cooling issues for fusion and fission
International Nuclear Information System (INIS)
Liquid metal application to nuclear power plants was initiated in a design of fast reactors with using sodium or lead bismuth eutectic, and developed into a sodium fast breeder reactor and lead bismuth fast reactor. In the development stage, Na and NaK were carefully compared and the former was chosen. In the nuclear fusion application, liquid metals of Li or LiPb will be used as a coolant and tritium breeder. A nuclear reactor requires two materials of moderator and coolant. Water or sodium satisfies double duty, leading to the oligopoly situation by LWR or Na-FBR. The success of these reactors depends on the selection of coolant material that works as a moderator. On an analogy of this history, fusion power plant should be integrated to employ a coolant that works as tritium breeder, such as Li or LiPb. Technology progresses in the system design are introduced, which will have synergy effect for fusion
Liquid metal cooling issues for fusion and fission
Energy Technology Data Exchange (ETDEWEB)
Horiike, H. [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita City, Osaka 565-0871 (Japan)], E-mail: horiike@nucl.eng.osaka-u.ac.jp; Konishi, S. [Institute of Advanced Energy, Kyoto University, Gokasho, Uji City, Kyoto 611-0011 (Japan); Kondo, H.; Yamaguchi, A. [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita City, Osaka 565-0871 (Japan)
2008-12-15
Liquid metal application to nuclear power plants was initiated in a design of fast reactors with using sodium or lead bismuth eutectic, and developed into a sodium fast breeder reactor and lead bismuth fast reactor. In the development stage, Na and NaK were carefully compared and the former was chosen. In the nuclear fusion application, liquid metals of Li or LiPb will be used as a coolant and tritium breeder. A nuclear reactor requires two materials of moderator and coolant. Water or sodium satisfies double duty, leading to the oligopoly situation by LWR or Na-FBR. The success of these reactors depends on the selection of coolant material that works as a moderator. On an analogy of this history, fusion power plant should be integrated to employ a coolant that works as tritium breeder, such as Li or LiPb. Technology progresses in the system design are introduced, which will have synergy effect for fusion.
Magnetic mirror fusion-fission early history and applicability to other systems
International Nuclear Information System (INIS)
In the mid 1970s to mid 1980s the mirror program was stuck with a concept, the Standard Mirror that was Q ∼ 1 where Q=Pfusion/Pinjection. Heroic efforts were put into hybridizing thinking added energy and fuel sales would make a commercial product. At the same time the tokamak was thought to allow ignition and ultrahigh Q values of 20 or even higher. There was an effort to use neutral beams to drive the tokamak just like the mirror machines were driven in which case the Q value plunged to a few, however this was thought to be achievable decades earlier than the high Q versions. Meanwhile current drive and other features of the tokamak have seen the projected Q values come down to the range of 10. Meanwhile the mirror program got Q enhancement into high gear and various tandem mirrors projected Q values up towards 10 and with advanced features over 10 with axi-symmetric magnets (See R. F. Post papers), however the experimental program is all but non-existent. Meanwhile, the gas dynamic trap mirror system which is present day state-of-the-art can with low risk produce Q of ∼0.1 useful for a low risk, low cost neutron source for materials development useful for the development of materials for all fusion concepts (see Simonen white paper: 'A Physics-Based Strategy to Develop a Mirror Fusion-Fission Hybrid' and D.D. Ryutov, 'Axisymmetric MHD-stable mirror as a neutron source and a driver for a fusion-fission hybrid'). Many early hybrid designs with multi-disciplinary teams were carried out in great detail for the mirror system with its axi-symmetric blanket modules. It is recognized that most of these designs are adaptable to tokamak or inertial fusion geometry. When Q is low (1 to 2) economics gives a large economic penalty for high recirculating power. These early studies covered the three design types: Power production, fuel production and waste burning. All three had their place but power production fell away because every study showed fusion machines that were
High-flux fusion neutron source for transmutation of fission products
International Nuclear Information System (INIS)
Transmutation of long-lived fission products is often referred to as a crucial step toward harmonized Self-Consistent Nuclear Energy System. The feasibility of their incineration is determined by available neutron excess in the nuclear energy system as a whole and appropriate transmutation environment (neutron spectra and flux) in a dedicated transmuter. The present paper highlights the remarkable transmutation environment of Fusion Neutron Source with ITER-like plasma parameters in approaching the transmutation characteristics which are superior to that of fission and accelerator based transmuters. Quantitative example of zirconium and cesium transmutation is addressed. (author)
International Nuclear Information System (INIS)
An EPR fission plant is expected to operate from 2010 to 2070. In this time range a new generation of advanced fission reactors and several stages of fusion reactors from ITER to DEMO will emerge. Their viability in the competitive socio-economic environment and also their possible synergy benefits are discussed in this paper. The studied cases involve the Finnish EPR, Generation IV, and the EFDA Power Plant Conceptual Study Models A-D. The main focus is on economic and safety assessments. Some cross-cutting issues of technologies are discussed. Concerning the economic potential of both conceptual fusion power plants and those of Generation IV candidates, we have used the present Finnish EPR as a reference. Comparisons using various pricing methods are made for fusion and Generation IV: mass flow analyses together with engineering, construction and financial margins form one method and another one is based on simple scaling relations between components or structures with common technology level. In all these studies fusion competitiveness has to be improved in terms of plant availability and internal power recirculation. At present the best fission plants have a plant availability close to 95% and an internal power recirculation of the order of 3-4%. The operation and maintenance solutions of Model C and D show the right way for fusion. A remarkable rise of the fuel costs of present LWRs would first make the Generation IV breeder options and thereafter the fusion plants more competitive. The costs of safety related components, such as the containment and the equipment for severe accident mitigation (e.g. the core catcher in a LWR), should be accounted for and the extent to which the inherent fusion safety features could compensate such expenses should be analysed. For an overall assessment of the various nuclear options both internal and external costs are considered. (author)
H. Q. ZhangSchool of Physics, Peking University, Beijing, China; Zhang, C. L.; C. J. Lin; Liu, Z. H.; Yang, F.; Nasirov, A. K.; Mandaglio, G.; Manganaro, M.; Giardina, G.
2009-01-01
The angular distributions of fission fragments for the $^{32}$S+$^{184}$W reaction at center-of-mass energies of 118.8, 123.1, 127.3, 131.5, 135.8, 141.1 and 144.4 MeV were measured. The experimental fission excitation function is obtained. The fragment angular anisotropy ($\\mathcal{A}_{\\rm exp}$) is found by extrapolating the each fission angular distributions. The measured fission cross sections of the $^{32}$S+$^{182,184}$W reaction are decomposed into fusion-fission, qua...
The Criticality Calculation Of Fission Yield Of U-235 Solution And Its Radiation Dose
International Nuclear Information System (INIS)
The calculation assesment of fission yield of U-235 solution in the extraction and evaporation units has been performed for the prediction of that when the criticality accident occurs in the production of fuel element for the research reactor. The Grover Tuck and fission distribution probability methods are used in this case. The calculation result using the fission distribution probability methods show the fission of 2,7 x 1018 for the uranium concentration of 200 grams/litre and that of 2,5 x 1018 fissions for U of 40 grams/litre in the extraction unit. The calculation results from the evaporation unit revealed the fission of 3,1 x 1018 for 400 grams/litre uranium and 1,77 x 1018 fissions for 80 grams/litre uranium. Using the Grover Tuck calculation method give results that 8,267 x 1017 fissions and 2,878 x 1017 fissions respectively. Radiation dose of 200 gram/litre solution is about 1450,29 Rad for neutron and 4785,96 Rad for gamma ray
Preliminary calculations of medium-energy fission cross sections and spectra
International Nuclear Information System (INIS)
Nucleon-induced fission cross sections determined from a statistical preequilibrium model are used in conjunction with a new scission-point model of fission fragment mass, charge and excitation energy distributions to produce evaporation model calculations of particle and gamma spectra and multiplicities from fission. Comparisons are made to experiment for the 14.5-MeV neutron-induced fission of 238U. In addition, calculated particle and gamma spectra will be compared with the ENDF/B library for 2- and 5-MeV neutron-induced fission of 235U and 238U, respectively. Initial predictions for these same quantities for proton-induced fission reactions at energies up to 100 MeV will be presented and discussed. 6 refs., 3 figs
Fission yield calculation using toy model based on Monte Carlo simulation
Energy Technology Data Exchange (ETDEWEB)
Jubaidah, E-mail: jubaidah@student.itb.ac.id [Nuclear Physics and Biophysics Division, Department of Physics, Bandung Institute of Technology. Jl. Ganesa No. 10 Bandung – West Java, Indonesia 40132 (Indonesia); Physics Department, Faculty of Mathematics and Natural Science – State University of Medan. Jl. Willem Iskandar Pasar V Medan Estate – North Sumatera, Indonesia 20221 (Indonesia); Kurniadi, Rizal, E-mail: rijalk@fi.itb.ac.id [Nuclear Physics and Biophysics Division, Department of Physics, Bandung Institute of Technology. Jl. Ganesa No. 10 Bandung – West Java, Indonesia 40132 (Indonesia)
2015-09-30
Toy model is a new approximation in predicting fission yield distribution. Toy model assumes nucleus as an elastic toy consist of marbles. The number of marbles represents the number of nucleons, A. This toy nucleus is able to imitate the real nucleus properties. In this research, the toy nucleons are only influenced by central force. A heavy toy nucleus induced by a toy nucleon will be split into two fragments. These two fission fragments are called fission yield. In this research, energy entanglement is neglected. Fission process in toy model is illustrated by two Gaussian curves intersecting each other. There are five Gaussian parameters used in this research. They are scission point of the two curves (R{sub c}), mean of left curve (μ{sub L}) and mean of right curve (μ{sub R}), deviation of left curve (σ{sub L}) and deviation of right curve (σ{sub R}). The fission yields distribution is analyses based on Monte Carlo simulation. The result shows that variation in σ or µ can significanly move the average frequency of asymmetry fission yields. This also varies the range of fission yields distribution probability. In addition, variation in iteration coefficient only change the frequency of fission yields. Monte Carlo simulation for fission yield calculation using toy model successfully indicates the same tendency with experiment results, where average of light fission yield is in the range of 90fission yield is in about 135
Fission yield calculation using toy model based on Monte Carlo simulation
International Nuclear Information System (INIS)
Toy model is a new approximation in predicting fission yield distribution. Toy model assumes nucleus as an elastic toy consist of marbles. The number of marbles represents the number of nucleons, A. This toy nucleus is able to imitate the real nucleus properties. In this research, the toy nucleons are only influenced by central force. A heavy toy nucleus induced by a toy nucleon will be split into two fragments. These two fission fragments are called fission yield. In this research, energy entanglement is neglected. Fission process in toy model is illustrated by two Gaussian curves intersecting each other. There are five Gaussian parameters used in this research. They are scission point of the two curves (Rc), mean of left curve (μL) and mean of right curve (μR), deviation of left curve (σL) and deviation of right curve (σR). The fission yields distribution is analyses based on Monte Carlo simulation. The result shows that variation in σ or µ can significanly move the average frequency of asymmetry fission yields. This also varies the range of fission yields distribution probability. In addition, variation in iteration coefficient only change the frequency of fission yields. Monte Carlo simulation for fission yield calculation using toy model successfully indicates the same tendency with experiment results, where average of light fission yield is in the range of 90fission yield is in about 135
Economic implications of fusion-fission energy systems
International Nuclear Information System (INIS)
The principal conclusions that can be made based on the estimated costs reported in this paper are twofold. First, hybrid reactors operating symbiotically with conventional fission reactors are a potentially attractive supply alternative. Estimated hybrid energy system costs are slightly greater than estimated costs of the most attractive alternatives. However, given the technological, economic, and institutional uncertainties associated with future energy supply, differences of such magnitude are of little significance. Second, to be economically viable, hybrid reactors must be both fuel producers and electricity producers. A data point representing each hybrid reactor driver-blanket concept is plotted as a function of net electrical production efficiency and annual fuel production. The plots illustrate that the most economically viable reactor concepts are those that produce both fuel and electricity
A fusion-fission reactor driven by plasma-liner impact
International Nuclear Information System (INIS)
It is shown that the impact of a quasi-spherical plasma liner on a spherical solid liner can produce a highly luminous source of soft X-rays. This radiation can be used for the ablation of an inner spherical liner, which can be thus accelerated to speeds above 107 cm/sec. Such a liner should be able to compress a core of fissionable material, surrounded by a D-T mantle to fission - criticality. The burst of the fission energy then ignites the D-T mantle which produces a larger burst of fusion energy. The energy liberated in such a microexplosion is estimated to be of the order of 1 GJ. An apparatus based on a symmetrical plasma-focus geometry should be able to produce the plasma liner. A reactor combining these concepts is described. (orig.)
Chen, Yong-Jing; Min, Jia; Liu, Ting-Jin; Shu, Neng-Chuan
2013-01-01
The prompt fission neutron spectra for neutron-induced fission of 233U for low energy neutrons (below 6 MeV) are calculated using the nuclear evaporation theory with a semi-empirical method, in which the partition of the total excitation energy between the fission fragments for the nth+233U fission reactions are determined with the available experimental and evaluation data. The calculated prompt fission neutron spectra agree well with the experimental data. The proportions of high- energy ou...
Systems Modeling For The Laser Fusion-Fission Energy (LIFE) Power Plant
Energy Technology Data Exchange (ETDEWEB)
Meier, W R; Abbott, R; Beach, R; Blink, J; Caird, J; Erlandson, A; Farmer, J; Halsey, W; Ladran, T; Latkowski, J; MacIntyre, A; Miles, R; Storm, E
2008-10-02
A systems model has been developed for the Laser Inertial Fusion-Fission Energy (LIFE) power plant. It combines cost-performance scaling models for the major subsystems of the plant including the laser, inertial fusion target factory, engine (i.e., the chamber including the fission and tritium breeding blankets), energy conversion systems and balance of plant. The LIFE plant model is being used to evaluate design trade-offs and to identify high-leverage R&D. At this point, we are focused more on doing self consistent design trades and optimization as opposed to trying to predict a cost of electricity with a high degree of certainty. Key results show the advantage of large scale (>1000 MWe) plants and the importance of minimizing the cost of diodes and balance of plant cost.
Durchfort, Nina; Verhoef, Shane; Vaughn, Michael B.; Shrestha, Rishna; Adam, Dieter; Kaplan, Jerry; Ward, Diane McVey
2011-01-01
Chediak-Higashi Syndrome is an autosomal recessive disorder that affects vesicle morphology. The Chs1/Lyst protein is a member of the BEACH family of proteins. The absence of Chs1/Lyst gives rise to enlarged lysosomes. Lysosome size is regulated by a balance between vesicle fusion and fission and can be reversibly altered by acidifying the cytoplasm using Acetate Ringer’s or by incubating with the drug vacuolin-1. We took advantage of these procedures to determine rates of lysosome fusion and...
12Cr-1Mo steel for fission and fusion applications
International Nuclear Information System (INIS)
A 12Cr-1Mo martensitic stainless steel has been selected as a candidate material for both Liquid Metal Fast Breeder duct applications and Tokamak Fusion Reactor first wall applications. As such, it represents the ferritic stainless steel alloy class for use as structural components in advanced energy systems. The bases for selecting 12Cr-1Mo for these applications are described and results are presented describing the irradiation resistance of this material following irradiation to high fluence in a fast reactor environment. Discussion is centered on anticipated temper embrittlement response in this class of materials
Ong, S. B.; Kalkhoran, S B; Cabrera-Fuentes, H A; Hausenloy, D.J.
2015-01-01
The past decade has witnessed a number of exciting developments in the field of mitochondrial dynamics – a phenomenon in which changes in mitochondrial shape and movement impact on cellular physiology and pathology. By undergoing fusion and fission, mitochondria are able to change their morphology between elongated interconnected networks and discrete fragmented structures, respectively. The cardiac mitochondria, in particular, have garnered much interest due to their unique spatial arrangeme...
Hall, A.; Burke, N; Dongworth, R.; Hausenloy, D.
2014-01-01
Mitochondria are no longer considered to be solely the static powerhouses of the cell. While they are undoubtedly essential to sustaining life and meeting the energy requirements of the cell through oxidative phosphorylation, they are now regarded as highly dynamic organelles with multiple funtions, playing key roles in cell survival and death. In this review, we discuss the emerging role of mitochondrial fusion and fission proteins, as novel therapeutic targets for treating a wide range of c...
System model for analysis of the mirror fusion-fission reactor
International Nuclear Information System (INIS)
This report describes a system model for the mirror fusion-fission reactor. In this model we include a reactor description as well as analyses of capital cost and blanket fuel management. In addition, we provide an economic analysis evaluating the cost of producing the two hybrid products, fissile fuel and electricity. We also furnish the results of a limited parametric analysis of the modeled reactor, illustrating the technological and economic implications of varying some important reactor design parameters
System model for analysis of the mirror fusion-fission reactor
Energy Technology Data Exchange (ETDEWEB)
Bender, D.J.; Carlson, G.A.
1977-10-12
This report describes a system model for the mirror fusion-fission reactor. In this model we include a reactor description as well as analyses of capital cost and blanket fuel management. In addition, we provide an economic analysis evaluating the cost of producing the two hybrid products, fissile fuel and electricity. We also furnish the results of a limited parametric analysis of the modeled reactor, illustrating the technological and economic implications of varying some important reactor design parameters.
Calculation of Prompt Fission Neutron Spectra for ~(235)U (n,f)
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
The prompt fission neutron spectra for neutron-induced fission of 235U at En<5 MeV are calculated using the nuclear evaporation theory with a semi-empirical model, in which the non-constant temperature and the constant temperature related to the Fermi gas model
Nuclear fusion and fission, and related technologies department: 2007 progress report
International Nuclear Information System (INIS)
ENEA continues to contribute to broadening plasma physics knowledge as well as to developing the relevant technologies in the framework of the EURATOM-ENEA Association for fusion. This report describes the 2007 research activities carried out by the ENEA Fusion Research Group of the Nuclear Fusion and Fission, and Related Technologies Department (FPN). Other ENEA research groups also contributed to the activities. The following fields were addressed: magnetically confined nuclear fusion (physics and technology), superconductivity and inertial fusion. Planning of the 2007 fusion activities took into account the different scenarios determined by the new organisation of the European programme based on the start of ITER construction. The establishment of the ITER International Organisation and the European Domestic Agency (Fusion for Energy) required a new organisational scheme. This has implied not only the implementation of a more project oriented structure but also the need to launch the constitution of a consortium agreement between the Associations in order to cope with the needs for the design and construction of the components of ITER that require specific know-how, e.g., diagnostics and test blanket module
Role of Fission Reactors and IFMIF in the Fusion Materials Programme
International Nuclear Information System (INIS)
In fusion power reactors, the plasma facing (first wall and divertor) and breeding blanket components will suffer irradiation by an intense flux of 14.1 MeV neutrons coming from the plasma. These fusion neutrons will produce nuclear transmutation reactions and atomic displacement cascades causing the presence of impurities and defects. Therefore, the chemical composition and the microstructure of the materials will change after irradiation, affecting its physical and mechanical properties. The study and evaluation of the changes in the material properties under irradiation is a top priority for the design of a fusion reactor. Key irradiation parameters include the accumulated damage, expressed in the number of displacements per atom or dpa, the damage rate in dpa/s, the rates of production of impurities (e.g. ppm(He)/dpa and ppm(H)/dpa ratios) and the temperature of the materials under irradiation. Unfortunately, at the moment, the existing sources of 14 MeV neutrons have very small intensity and do not allow us to get significant damage accumulation in a reasonable time. Therefore, it is necessary to simulate irradiation by fusion neutrons through the use of fission neutrons, high energy protons or heavy ions. Although the irradiation conditions provided by such particles are very different from those expected to occur in a fusion power reactor, especially in terms of damage rate and rates of production of impurities, relevant information can be obtained from present available fission reactors. In the paper a list with relevant experiments suitable for the fusion community is given, and the role of the future International Fusion Materials Irradiation Facility is discussed. (author)
Pion-Induced Fission of 209Bi and 119Sn:. Measurements, Calculations, Analyses and Comparison
Rana, Mukhtar Ahmed; Sher, Gul; Manzoor, Shahid; Shehzad, M. I.
Cross-sections for the π--induced fission of 209Bi and 119Sn have been measured using the most sensitive CR-39 solid-state nuclear track detector. In experiments, target-detector stacks were exposed to negative pions of energy 500, 672, 1068, and 1665 MeV at the Brookhaven National Laboratory, USA. An important aspect of the present paper is the comparison of pion-induced fission fragment spectra of above mentioned nuclei with the spontaneous fission fragment spectra of 252Cf. This comparison is made in terms of fission fragment track lengths in the CR-39 detectors. Measurement results are compared with calculations of Monte Carlo and statistical weight functions methods using the computer code CEM95. Agreement between measurements and calculations is fairly good for 209Bi target nuclei whereas it is indigent for the case of 119Sn. The possibilities of the trustworthy calculations, using the computer code CEM95, comparable with measurements of pion-induced fission in intermediate and heavy nuclei are explored by employing various systematics available in the code. Energy dependence of pion-induced fission in 119Sn and 209Bi is analyzed employing a newly defined parameter geometric-size-normalized fission cross-section (χfg). It is found that the collective nuclear excitations, which may lead to fission, become more probable for both 209Bi and 119Sn nuclei with increasing energy of negative pions from 500 to 1665 MeV.
International Nuclear Information System (INIS)
We have performed direct numerical calculations of the kinetics of relaxation in the system of surfactant spherical micelles under joint action of the molecular mechanism with capture and emission of individual surfactant molecules by molecular aggregates and the mechanism of fusion and fission of the aggregates. As a basis, we have taken the difference equations of aggregation and fragmentation in the form of the generalized kinetic Smoluchowski equations for aggregate concentrations. The calculations have been made with using the droplet model of molecular surfactant aggregates and two modified Smoluchowski models for the coefficients of aggregate-monomer and aggregate-aggregate fusions which take into account the effects of the aggregate size and presence of hydrophobic spots on the aggregate surface. A full set of relaxation times and corresponding relaxation modes for nonequilibrium aggregate distribution in the aggregation number has been found. The dependencies of these relaxation times and modes on the total concentration of surfactant in the solution and the special parameter controlling the probability of fusion in collisions of micelles with other micelles have been studied
Energy Technology Data Exchange (ETDEWEB)
Zakharov, Anatoly I.; Adzhemyan, Loran Ts.; Shchekin, Alexander K., E-mail: akshch@list.ru [Department of Statistical Physics, Faculty of Physics, St. Petersburg State University, Ulyanovskaya 1, Petrodvoretz, St. Petersburg 198504 (Russian Federation)
2015-09-28
We have performed direct numerical calculations of the kinetics of relaxation in the system of surfactant spherical micelles under joint action of the molecular mechanism with capture and emission of individual surfactant molecules by molecular aggregates and the mechanism of fusion and fission of the aggregates. As a basis, we have taken the difference equations of aggregation and fragmentation in the form of the generalized kinetic Smoluchowski equations for aggregate concentrations. The calculations have been made with using the droplet model of molecular surfactant aggregates and two modified Smoluchowski models for the coefficients of aggregate-monomer and aggregate-aggregate fusions which take into account the effects of the aggregate size and presence of hydrophobic spots on the aggregate surface. A full set of relaxation times and corresponding relaxation modes for nonequilibrium aggregate distribution in the aggregation number has been found. The dependencies of these relaxation times and modes on the total concentration of surfactant in the solution and the special parameter controlling the probability of fusion in collisions of micelles with other micelles have been studied.
Saita, Shotaro; Ishihara, Takaya; Maeda, Maki; Iemura, Shun-Ichiro; Natsume, Tohru; Mihara, Katsuyoshi; Ishihara, Naotada
2016-05-01
Mitochondrial morphology is dynamically regulated by fusion and fission. Several GTPase proteins control fusion and fission, and posttranslational modifications of these proteins are important for the regulation. However, it has not been clarified how the fusion and fission is balanced. Here, we report the molecular mechanism to regulate mitochondrial morphology in mammalian cells. Ablation of the mitochondrial fission, by repression of Drp1 or Mff, or by over-expression of MiD49 or MiD51, results in a reduction in the fusion GTPase mitofusins (Mfn1 and Mfn2) in outer membrane and long form of OPA1 (L-OPA1) in inner membrane. RNAi- or CRISPR-induced ablation of Drp1 in HeLa cells enhanced the degradation of Mfns via the ubiquitin-proteasome system (UPS). We further found that UPS-related protein BAT3/BAG6, here we identified as Mfn2-interacting protein, was implicated in the turnover of Mfns in the absence of mitochondrial fission. Ablation of the mitochondrial fission also enhanced the proteolytic cleavage of L-OPA1 to soluble S-OPA1, and the OPA1 processing was reversed by inhibition of the inner membrane protease OMA1 independent on the mitochondrial membrane potential. Our findings showed that the distinct degradation systems of the mitochondrial fusion proteins in different locations are enhanced in response to the mitochondrial morphology. PMID:26935475
Fusion and quasi-fission dynamics in nearly-symmetric reactions
Wang, Ning; Zhao, Kai; Li, ZhuXia
2015-11-01
Some nearly-symmetric fusion reactions are systematically investigated with the improved quantum molecular dynamics (ImQMD) model. By introducing two-body inelastic scattering in the Fermi constraint procedure, the stability of an individual nucleus and the description of fusion cross sections at energies near the Coulomb barrier can be further improved. Simultaneously, the quasifission process in 154Sm+160Gd is also investigated with the microscopic dynamics model for the first time. We find that at energies above the Bass barrier, the fusion probability is smaller than 10-5 for this reaction, and the nuclear contact time is generally smaller than 1500 fm/ c. From the central collisions of Sm+Gd, the neutron-rich fragments such as 164,165Gd, 192W can be produced in the ImQMD simulations, which implies that the quasi-fission reaction could be an alternative way to synthesize new neutron-rich heavy nuclei.
Block-free optical quantum Banyan network based on quantum state fusion and fission
International Nuclear Information System (INIS)
Optical switch fabric plays an important role in building multiple-user optical quantum communication networks. Owing to its self-routing property and low complexity, a banyan network is widely used for building switch fabric. While, there is no efficient way to remove internal blocking in a banyan network in a classical way, quantum state fusion, by which the two-dimensional internal quantum states of two photons could be combined into a four-dimensional internal state of a single photon, makes it possible to solve this problem. In this paper, we convert the output mode of quantum state fusion from spatial-polarization mode into time-polarization mode. By combining modified quantum state fusion and quantum state fission with quantum Fredkin gate, we propose a practical scheme to build an optical quantum switch unit which is block free. The scheme can be extended to building more complex units, four of which are shown in this paper. (general)
Comparative evaluation of solar, fission, fusion, and fossil energy resources, part 3
Clement, J. D.; Reupke, W. A.
1974-01-01
The role of nuclear fission reactors in becoming an important power source in the world is discussed. The supply of fissile nuclear fuel will be severely depleted by the year 2000. With breeder reactors the world supply of uranium could last thousands of years. However, breeder reactors have problems of a large radioactive inventory and an accident potential which could present an unacceptable hazard. Although breeder reactors afford a possible solution to the energy shortage, their ultimate role will depend on demonstrated safety and acceptable risks and environmental effects. Fusion power would also be a long range, essentially permanent, solution to the world's energy problem. Fusion appears to compare favorably with breeders in safety and environmental effects. Research comparing a controlled fusion reactor with the breeder reactor in solving our long range energy needs is discussed.
An investigation of fission models for high-energy radiation transport calculations
International Nuclear Information System (INIS)
An investigation of high-energy fission models for use in the HETC code has been made. The validation work has been directed checking the accuracy of the high-energy radiation transport computer code HETC to investigate the appropriate model for routine calculations, particularly for spallation neutron source applications. Model calculations are given in terms of neutron production, fission fragment energy release, and residual nuclei production for high-energy protons incident on thin uranium targets. The effect of the fission models on neutron production from thick uranium targets is also shown. (orig.)
Mass asymmetry of fusion and fission processes induced in heavy ion reaction
International Nuclear Information System (INIS)
Simple parametrisations of nuclear shapes able to describe the essential features of the fission and fusion processes were introduced. The Myers-Swiatecki (1967) liquid drop model and its generalisations: the Krape-Nix (1974) finite range of nuclear forces model and the Krappe-Nix-Sierk (1979) folded Yukawa-plus-exponential model, were extended for the nuclear systems with different charge densities. Some information concerning the interaction barrier (Esub(I)) the energy release (Q) and the fission barrier (Esub(b)) trends of variation with mass and charge asymmetry were obtained from the energy at infinite separation distance between ions (or fission fragments), at the touching point and at the fused spherical system. Good agreement with experimental data was obtained and an empirical relationship for the estimation of the interaction barriers was derived. The reaction parteners, for which it is important to take into account the charge density difference, were identified and the orders of magnitude of the errors on Esub(I), Q and Esub(b) made if this difference is ignored, were estimated. The nonaxiality of the nuclear shape at the first saddle point was demonstrated on a simple model allowing to decrease the computer running time by 3 orders of magnitude. The asymmetric spheroidal oscillator, introduced by the author, can be used to study the fission process. The fission theory was successfully applied to compute the Q-values and the life-times of the alpha decay. Good agreement (within +-0.8 orders of magnitude) of the theoretical half-lives with experimental ones, over a range of 24 orders of magnitude was obtained. This is a strong argument that the alpha decay could be considered a fission process with very high mass asymmetry and charge density asymmetry. (author)
Baden, Andrea L; Webster, Timothy H; Kamilar, Jason M
2016-02-01
Ruffed lemurs (genus Varecia) are often described as having a flexible social organization, such that both cohesive (low fission-fusion dynamics) and fluid (high fission-fusion dynamics) grouping patterns have been observed. In ruffed lemur communities with high fission-fusion dynamics, group members vary in their temporal and spatial dispersion throughout a communally defended territory. These patterns have been likened to those observed in several haplorrhine species that exhibit the most fluid types of fission-fusion social organization (e.g., Pan and Ateles). To substantiate and further refine these claims, we describe the fission-fusion dynamics of a black-and-white ruffed lemur (Varecia variegata) community at Mangevo, an undisturbed primary rainforest site in Ranomafana National Park, Madagascar. We collected instantaneous group scan samples from August 2007-December 2008 (4,044 observation hours) to study and characterize patterns of subgroup size, composition, cohesion, and social association. In 16 consecutive months, we never found all members of the community together. In fact, individuals spent nearly half of their time alone. Subgroups were small, cohesive, and typically of mixed-sex composition. Mixed-sex subgroups were significantly larger, less cohesive, and more common than either male-only or female-only subgroups. Subgroup dynamics were related to shifts in climate, phenology of preferred fruit species, and female reproductive state. On average, association indices were low. Males and females were equally gregarious; however, adult male-male associations were significantly weaker than any other association type. Results presented herein document striking differences in fission-fusion dynamics between black-and-white ruffed lemurs and haplorrhines, while also demonstrating many broad-scale similarities to haplorrhine taxa that possess the most fluid fission-fusion societies. PMID:26606154
Disentangling association patterns in fission-fusion societies using African buffalo as an example
Cross, P.C.; Lloyd-Smith, J. O.; Getz, W.M.
2005-01-01
A description of the social network of a population aids us in understanding dispersal, the spread of disease, and genetic structure in that population. Many animal populations can be classified as fission–fusion societies, whereby groups form and separate over time. Examples discussed in the literature include ungulates, primates and cetaceans (Lott and Minta, 1983, Whitehead et al., 1991, Henzi et al., 1997, Christal et al., 1998 and Chilvers and Corkeron, 2002). In this study, we use a heuristic simulation model to illustrate potential problems in applying traditional techniques of association analysis to fission–fusion societies and propose a new index of association: the fission decision index (FDI). We compare the conclusions resulting from traditional methods with those of the FDI using data from African buffalo, Syncerus caffer, in the Kruger National Park. The traditional approach suggested that the buffalo population was spatially and temporally structured into four different ‘herds’ with adult males only peripherally associated with mixed herds. Our FDI method indicated that association decisions of adult males appeared random, but those of other sex and age categories were nonrandom, particularly when we included the fission events associated with adult males. Furthermore, the amount of time that individuals spent together was only weakly correlated with their propensity to remain together during fission events. We conclude with a discussion of the applicability of the FDI to other studies.
International Nuclear Information System (INIS)
Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from an LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with each other or a target block in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., 137Cs or 90Sr. The 14-MeV fusion neutrons released during the pellet burn cause transmutation reactions (e.g., (n, 2n), (n, α), etc.) that convert the long lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product
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The method for calculation of energy dependence of fusion (in general case the sum of complete and incomplete fusion, quasi fission and deep inelastic collisions) and total peripheral reaction cross sections is developed on the basis of finite set of elastic scattering angular distributions analysis for given pair of nuclei. Predictive possibilities of the method are illustrated for the 16O+208Pb system, for which calculations are made in the laboratory energy interval Elab = 70 - 450 MeV
International Nuclear Information System (INIS)
The ''Workshop on Advanced Computational Materials Science: Application to Fusion and Generation IV Fission Reactors'' was convened to determine the degree to which an increased effort in modeling and simulation could help bridge the gap between the data that is needed to support the implementation of these advanced nuclear technologies and the data that can be obtained in available experimental facilities. The need to develop materials capable of performing in the severe operating environments expected in fusion and fission (Generation IV) reactors represents a significant challenge in materials science. There is a range of potential Gen-IV fission reactor design concepts and each concept has its own unique demands. Improved economic performance is a major goal of the Gen-IV designs. As a result, most designs call for significantly higher operating temperatures than the current generation of LWRs to obtain higher thermal efficiency. In many cases, the desired operating temperatures rule out the use of the structural alloys employed today. The very high operating temperature (up to 1000 C) associated with the NGNP is a prime example of an attractive new system that will require the development of new structural materials. Fusion power plants represent an even greater challenge to structural materials development and application. The operating temperatures, neutron exposure levels and thermo-mechanical stresses are comparable to or greater than those for proposed Gen-IV fission reactors. In addition, the transmutation products created in the structural materials by the high energy neutrons produced in the DT plasma can profoundly influence the microstructural evolution and mechanical behavior of these materials. Although the workshop addressed issues relevant to both Gen-IV and fusion reactor materials, much of the discussion focused on fusion; the same focus is reflected in this report. Most of the physical models and computational methods presented during the
An economics method for symbiotic fusion-fission electricity generation systems
International Nuclear Information System (INIS)
A self-consistent analytical methodology for evaluating the economic incentives for symbiotic electricity generation systems that consist of fusion breeder reactors and supported fission converter reactors is developed. This methodology employs a discounted cash flow analysis of breeder and converter direct operating costs and indirect capital costs, as well as a novel treatment of fissile inventory charges. Three figures of merit are emphasized: the levelized cost of electricity generated by the symbiotic system; the levelized cost of fuel exchanged by the breeder and converter reactors in the system; and the equivalent cost of fuel to produce the same levelized electricity cost in a alternatively fueled converter reactor. A fission converter operating on the current once-through fuel cycle is a special case of the above. The method is equally applicable to symbiotic systems that utilize spallation accelerator breeder reactors
Fusion-Fission of $^{16}O+^{197}Au$ at Sub-Barrier Energies
Back, B B; Janssens, R V F; Henderson, D J; Shumard, B R; Lister, C J; Peterson, D; Rehm, K E; Tanihata, I; Tang, X; Wang, X; Zhu, S
2006-01-01
The recent discovery of heavy-ion fusion hindrance at far sub-barrier energies has focused much attention on both experimental and theoretical studies of this phenomenon. Most of the experimental evidence comes from medium-heavy systems such as Ni+Ni to Zr+Zr, for which the compound system decays primarily by charged-particle evaporation. In order to study heavier systems, it is, however, necessary to measure also the fraction of the decay that goes into fission fragments. In the present work we have, therefore, measured the fission cross section of 16O+197Au down to unprecedented far sub-barrier energies using a large position sensitive PPAC placed at backward angles. The preliminary cross sections will be discussed and compared to earlier studies at near-barrier energies. No conclusive evidence for sub-barrier hindrance was found, probably because the measurements were not extended to sufficiently low energies.
International Nuclear Information System (INIS)
Neutronics calculations were performed to analysis the parameters of blanket energy multiplication factor (M) and tritium breeding ratio (TBR) in a fusion-fission hybrid reactor for energy production named FDS-EM (Energy Multiplier) blanket. The most significant and main goal of the water-cooled FDS-EM blanket is to achieve the energy gain of about 1 GW with self-sustaining tritium, which can operate for as long as possible without fuel unloading and reloading. The preliminarily designed neutronics parameters for FDS-EM were presented, which show that the blanket loaded with the Nuclear Waste (transuranic from 33 000 MWD/MTU PWR and depleted uranium) for energy multiplication (M≅90) with tritium self-sufficiency can operate for at least 10 years without fuel unloading and reloading. (authors)
Investigation of tritium and 233U breeding in a fission-fusion hybrid reactor fuelling with ThO2
International Nuclear Information System (INIS)
In the world, thorium reserves are three times more than natural Uranium reserves. It is planned in the near future that nuclear reactors will use thorium as a fuel. Thorium is not a fissile isotope because it doesn't make fission with thermal neutrons so it could be converted to 233U isotope which has very high quality fission cross-section with thermal neutrons. 233U isotope can be used in present LWRs as an enrichment fuel. In the fusion reactors, tritium is the most important fossil fuel. Because tritium is not natural isotope, it has to be produced in the reactor. The purpose of this work is to investigate the tritium and 233U breeding in a fission-fusion hybrid reactor fuelling with ThO2 for Δt=10 days during a reactor operation period in five years. The neutronic analysis is performed on an experimental hybrid blanket geometry. In the center of the hybrid blanket, there is a line neutron source in a cylindrical cavity, which simulates the fusion plasma chamber where high energy neutrons (14.1 MeV) are produced. The conventional fusion reaction delivers the external neutron source for blankets following, 2D + 3T →? 4He (3.5 MeV) + n (14.1 MeV). (1) The fuel zone made up of natural-ThO2 fuel and it is cooled with different coolants. In this work, five different moderator materials, which are Li2BeF4, LiF-NaF-BeF2, Li20Sn80, natural Lithium and Li17Pb83, are used as coolants. The radial reflector, called tritium breeding zones, is made of different Lithium compounds and graphite in sandwich structure. In the work, eight different Lithium compounds were used as tritium breeders in the tritium breeding zones, which are Li3N, Li2O, Li2O2, Li2TiO3, Li4SiO3, Li2ZrO3, LiBr and LiH. Neutron transport calculations are conducted in spherical geometry with the help of SCALE4.4A SYSTEM by solving the Boltzmann transport equation with code CSAS and XSDRNPM, under consideration of unresolved and resolved resonances, in S8-P3 approximation with Gaussian quadratures using
Calculating fusion neutron energy spectra from arbitrary reactant distributions
Eriksson, J.; Conroy, S.; Andersson Sundén, E.; Hellesen, C.
2016-02-01
The Directional Relativistic Spectrum Simulator (DRESS) code can perform Monte-Carlo calculations of reaction product spectra from arbitrary reactant distributions, using fully relativistic kinematics. The code is set up to calculate energy spectra from neutrons and alpha particles produced in the D(d, n)3He and T(d, n)4He fusion reactions, but any two-body reaction can be simulated by including the corresponding cross section. The code has been thoroughly tested. The kinematics calculations have been benchmarked against the kinematics module of the ROOT Data Analysis Framework. Calculated neutron energy spectra have been validated against tabulated fusion reactivities and against an exact analytical expression for the thermonuclear fusion neutron spectrum, with good agreement. The DRESS code will be used as the core of a detailed synthetic diagnostic framework for neutron measurements at the JET and MAST tokamaks.
Fission product inventory calculation by a CASMO/ORIGEN coupling program
International Nuclear Information System (INIS)
A CASMO/ORIGEN coupling utility program was developed to predict the composition of all the fission products in spent PWR fuels. The coupling program reads the CASMO output file, modifies the ORIGEN cross section library and reconstructs the ORIGEN input file at each depletion step. In ORIGEN, the burnup equation is solved for actinides and fission products based on the fission reaction rates and depletion flux of CASMO. A sample calculation has been performed using a 14 x 14 PWR fuel assembly and the results are given in this paper
Fission product inventory calculation by a CASMO/ORIGEN coupling program
Energy Technology Data Exchange (ETDEWEB)
Kim, Do Heon; Kim, Jong Kyung [Hanyang University, Seoul (Korea, Republic of); Choi, Hang Bok; Roh, Gyu Hong; Jung, In Ha [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)
1997-12-31
A CASMO/ORIGEN coupling utility program was developed to predict the composition of all the fission products in spent PWR fuels. The coupling program reads the CASMO output file, modifies the ORIGEN cross section library and reconstructs the ORIGEN input file at each depletion step. In ORIGEN, the burnup equation is solved for actinides and fission products based on the fission reaction rates and depletion flux of CASMO. A sample calculation has been performed using a 14 x 14 PWR fuel assembly and the results are given in this paper. 3 refs., 1 fig., 1 tab. (Author)
Calculation of prompt fission neutron spectra for 235U(n,f)
Institute of Scientific and Technical Information of China (English)
CHEN Yong-Jing; JIA Min; TAO Xi; QIAN Jing; LIU Ting-Jin; SHU Neng-Chuan
2012-01-01
The prompt fission neutron spectra for the neutron-induced fission of 235U at En ＜ 5 MeV are calculated using nuclear evaporation theory with a semi-empirical model,in which the nonconstant and constant temperatures related to the Fermi gas model are taken into account. The calculated prompt fission neutron spectra reproduce the experimental data well.For the n(thermal)+235U reaction,the average nuclear temperature of the fission fragment,and the probability distribution of the nuclear temperature,are discussed and compared with the Los Alamos model.The energy carried away by γ rays emitted from each fragment is also obtained and the results are in good agreement with the existing experimental data.
Effect of volume ratio between uranium and water on fusion-fission hybrid for energy production
International Nuclear Information System (INIS)
The theoretic model of MCORGS code, which is used in this paper to evaluate the effect of the volume ratio between uranium and water (VR) on a fusion-fission hybrid for energy production, is introduced. It is showed that at natural uranium case, the VR of 2:1 is preferred, since it can reach a comprise between energy multiplication and tritium breeding ratio, and the neutronics performance of the system can maintain more than 100 years. At the case of spent fuel from PWR, there are more room for selection of VR. Both energy multiplication and tritium breeding ratio will improve, however the fissile material breeding capacity will degrade. (authors)
Preliminary design and analysis on nuclear fuel cycle for fission-fusion hybrid spent fuel burner
International Nuclear Information System (INIS)
A wet-processing-based fuel cycle and a dry-processing were designed for a fission-fusion hybrid spent fuel burner (FDS-SFB). Mass flow of SFB was preliminarily analyzed. The feasibility analysis of initial loaded fuel inventory, recycle fuel fabrication and spent fuel reprocessing were preliminarily evaluated. The results of mass flow of FDS-SFB demonstrated that the initial loaded fuel inventory, recycle fuel fabrication and spent fuel reprocessing of nuclear fuel cycle of FDS-SFB is preliminarily feasible. (authors)
Steady-state fusion fission reactor concepts based on stellarator-mirror and mirror machines
International Nuclear Information System (INIS)
Neutron sources and hybrid reactors offer a possibility for application of fusion in a not too distant future. Steady-state operation on a time scale of a year without interruption is essential for such applications. In response to this need, our studies are focused on concepts which are not limited by pulsed operation. Special attention is put on mirror machines and a stellarator-mirror concept with localized neutron production. Reactor safety, magnetic coils, power amplification by fission, plasma heating, a radial constant of motion which provides a bounded radial motion in the collision free approximation are some of the issues addressed
International Nuclear Information System (INIS)
Yield-weighted average cross sections of neutron radiative capture, (n,2n), and (n,3n) reactions over prompt fission products (FPs) from 235U and 239Pu are calculated. The prompt fission production yields are taken from the ENDF/B-VII.0 library. The FPs for each fissile material exist over a range of approximately 1000 neutron-rich nuclides. Several nuclear reaction codes are utilized for calculating the cross sections on each individual fission product - EMPIRE-2.19, TALYS-1.0, GNASH, and CoH. The influence of the FP isomers on the average cross sections is examined with TALYS. We investigate the dependence of the average cross sections on the number of FPs taken for averaging. It is shown that the average capture cross section is much more sensitive to the number of FPs included, compared with the (n,2n) and (n,3n) reactions. An intercomparison of the calculated cross sections with the different reaction codes is carried out. In the capture reaction, EMPIRE predicted lower cross section than TALYS and CoH owing to different default assumptions used in the γ-ray strength function modeling. Moreover, the pre-equilibrium models implemented in each code give different predictions for the neutron-emission reactions, although the differences are relatively small. We also discuss a difference between the macroscopic and microscopic calculation options in TALYS for the pre-equilibrium model, optical potential model, and γ-ray strength function. The predictive capability of the reaction codes for the capture reaction is examined by comparing their calculations with the ENDF data, which are based on measurements. Compared with the historic Foster and Arthur's evaluation, our new (n,2n) predictions are similar, although our capture predictions are almost an order of magnitude higher. Recommended cross sections for use in applications have been tabulated in ENDF-formatted files. (author)
Augmentation of ENDF/B fission product gamma-ray spectra by calculated spectra
International Nuclear Information System (INIS)
Gamma-ray spectral data of the ENDF/B-V fission product decay data file have been augmented by calculated spectra. The calculations were performed with a model using beta strength functions and cascade gamma-ray transitions. The calculated spectra were applied to individual fission product nuclides. Comparisons with several hundred measured aggregate gamma spectra after fission were performed to confirm the applicability of the calculated spectra. The augmentation was extended to a preliminary ENDF/B-VI file, and to beta spectra. Appendix C provides information on the total decay energies for individual products and some comparisons of measured and aggregate values based on the preliminary ENDF/B-VI files. 15 refs., 411 figs
235U fission product gamma spectra: a comparison between experiment and calculation
International Nuclear Information System (INIS)
Recent measurements of 235U fission product gamma spectra (ORNL), after reduction to a broad group structure, were compared with results of corresponding summation calculations which were made with the UKFPDD-1 fission product data base. In order to facilitate convenient integration of the summation results, weighted sums of decaying exponentials were accurately fitted to them using an iterative least-squares method described. The comparisons between experiment and calculation reveal significant deficiencies in data for short-lived nuclides which prevent the accurate calculation of short-term ( 5 MeV are also examined briefly and possible causes for them are discussed. (author)
Fission Dynamics of Compound Nuclei
Iwata, Yoritaka; Heinz, Sophia
2012-01-01
Collisions between $^{248}$Cm and $^{48}$Ca are systematically investigated by time-dependent density functional calculations with evaporation prescription. Depending on the incident energy and impact parameter, fusion, deep-inelastic and quasi-fission events are expected to appear. In this paper, possible fission dynamics of compound nuclei is presented.
Fission source convergence of Monte Carlo criticality calculations in weakly coupled fissile arrays
International Nuclear Information System (INIS)
Anomalous fission source convergence in a Monte Carlo criticality calculation for a weakly coupled array of two fissile material units are demonstrated. Introducing coupling coefficients among array units, it is quantitatively explained that this anomaly is caused by an insufficient restoring force to the true distribution and its large statistical uncertainty, especially, in a symmetric system. A new approach for estimating the fission source intensity ratio in an array is proposed by obtaining the eigenvector of a coupling coefficient matrix. This method also gives the uncertainty of the ratio as well as the ratio, which is available for evaluating the accuracy of the obtained ratio. The correlation between a calculated keff and the fission source intensity ratio is formulated. It is illustrated theoretically and empirically that there is no significant correlation in a symmetric two-unit array system. In general, care should be taken that a calculated keff may be biased by an incorrect fission source distribution, especially, in a slightly asymmetric system. A regionwise weight adjustment method is developed such that the fission source intensity ratio is forced to converge to a predetermined ratio. Using this method, a satisfactory convergence can be achieved. A larger number of neutrons per generation is recommended for a Monte Carlo criticality calculation of a weakly coupled array of units. (author)
Status and prospects of nuclear power from fusion and from fission
International Nuclear Information System (INIS)
Full text: The advantages of nuclear power from fusion are inexhaustible fuel resources, ecological attractiveness, inherent safety, significantly lower level of radioactive wastes, and absence of the materials which could be used for weapons. Since the 1950s the intensive work resulted in a unique scientific and technological database. In 1985 M. Gorbachev, F. Mitterand and R. Reagan suggested to create the first experimental fusion reactor on an international basis. In 1988 an international team comprising specialists of the USSR, USA, EC and Japan started activities on the design of a reactor, which was named ITER, with active support from the IAEA. An engineering design of the 500 MW reactor was completed in 2001. The negotiations concerning ITER construction have been started. Canada, Japan, France and Spain proposed options for site selection. Canada, China and the Republic of Korea have joined the countries that had pioneered the project. The ITER would have important socio-economical and political implications for the world community. The time for creating such a reactor is ripe. The nuclear power from fission is an advanced technology providing for 16% of electricity in the world. The IAEA project INPRO was started after the Russian Federation President Vladimir V. Putin stated his Initiative at the UN General Assembly in 2000. This project addresses the strategic issues of development of future nuclear energy for the world from nuclear fission. INPRO has made a conclusion that Nuclear Fuel Cycle (NFC) is a system-creating factor. Prospects of such power depend on the solution of NFC back-end problem. It is necessary to begin the formation of NFC international structures, as a major component of the world fission power system. The establishment of an international research centre on spent fuel treatment technology and on radioactive waste storage is a practical step in this direction. (author)
Global calculations of fission barriers and beta-decay properties of neutron-rich nuclei
Energy Technology Data Exchange (ETDEWEB)
Moller, P. (Peter); Sierk, A. J. (Arnold J.); Ichikawa, Takatoshi; Iwamoto, A. (Akira)
2004-01-01
Recently we have performed large-scale calculations of fission barriers in the actinide region based on five-dimensional deformation spaces with more than 3,000,000 deformation points for each potential-energy surface. We have determined new model constants. We have also extended our model to axially asymmetric shapes. We apply these techniques to the calculations of fission barriers of heavy nuclei from the line of beta stability to the r-process line. The aim is to study fission near the end of the r-process. We have also extended our model of {beta}-decay so that allowed Gamow-Teller transitions are treated in a quasi-particle random-phase approximation as earlier, but we now also consider first-forbidden transitions in the statistical gross theory. We discuss the properties of this enhanced model and present results of global calculations.
International Nuclear Information System (INIS)
Recently, direct measurements of fission cross-sections for 233Pa (n, f) reaction are available which stimulated the calculation of fission cross-sections for this reaction. For this calculation we have derived an analytical barrier formula based on microscopic-macroscopic description by fitting the actinide fission barrier data for the double humped barrier. Pairing effects have also been taken into account. The cross sections calculated for using the analytical barrier formula with the code EMPIRE 2.19 give better agreement with the available measurements. (author)
Calculated leaching of certain fission products from a cylinder of French glass
International Nuclear Information System (INIS)
The probable total leaching of the most important fission products and actinides have been tabulated for a cylinder of French HLW glass with approximately 9 percent fission products. The calculations cover the period between 30 and 10000 years after removal from the reactor. The cylinder is of the type planned for the introduction of the HLW into Swedish crystalline rocks. All the components are supposed to have the same leach rate. The calculations also include the probable thickness of eroded glass layer/year. (author)
The Sustainable Nuclear Future: Fission and Fusion E.M. Campbell Logos Technologies
Campbell, E. Michael
2010-02-01
Global industrialization, the concern over rising CO2 levels in the atmosphere and other negative environmental effects due to the burning of hydrocarbon fuels and the need to insulate the cost of energy from fuel price volatility have led to a renewed interest in nuclear power. Many of the plants under construction are similar to the existing light water reactors but incorporate modern engineering and enhanced safety features. These reactors, while mature, safe and reliable sources of electrical power have limited efficiency in converting fission power to useful work, require significant amounts of water, and must deal with the issues of nuclear waste (spent fuel), safety, and weapons proliferation. If nuclear power is to sustain its present share of the world's growing energy needs let alone displace carbon based fuels, more than 1000 reactors will be needed by mid century. For this to occur new reactors that are more efficient, versatile in their energy markets, require minimal or no water, produce less waste and more robust waste forms, are inherently safe and minimize proliferation concerns will be necessary. Graphite moderated, ceramic coated fuel, and He cooled designs are reactors that can satisfy these requirements. Along with other generation IV fast reactors that can further reduce the amounts of spent fuel and extend fuel resources, such a nuclear expansion is possible. Furthermore, facilities either in early operations or under construction should demonstrate the next step in fusion energy development in which energy gain is produced. This demonstration will catalyze fusion energy development and lead to the ultimate development of the next generation of nuclear reactors. In this presentation the role of advanced fission reactors and future fusion reactors in the expansion of nuclear power will be discussed including synergies with the existing worldwide nuclear fleet. )
Evaluation of fission product worth margins in PWR spent nuclear fuel burnup credit calculations
International Nuclear Information System (INIS)
Current criticality safety calculations for the transportation of irradiated LWR fuel make the very conservative assumption that the fuel is fresh. This results in a very substantial overprediction of the actual keff of the transportation casks; in certain cases, this decreases the amount of spent fuel which can be loaded in a cask, and increases the cost of transporting the spent fuel to the repository. Accounting for the change of reactivity due to fuel depletion is usually referred to as ''burnup credit.'' The US DOE is currently funding a program aimed at establishing an actinide only burnup credit methodology (in this case, the calculated reactivity takes into account the buildup or depletion of a limited number of actinides). This work is undergoing NRC review. While this methodology is being validated on a significant experimental basis, it implicitly relies on additional margins: in particular, the absorption of neutrons by certain actinides and by all fission products is not taken into account. This provides an important additional margin and helps guarantee that the methodology is conservative provided these neglected absorption are known with reasonable accuracy. This report establishes the accuracy of fission product absorption rate calculations: (1) the analysis of European fission product worth experiments demonstrates that fission product cross-sections available in the US provide very good predictions of fission product worth; (2) this is confirmed by a direct comparison of European and US cross section evaluations; (3) accuracy of Spent Nuclear Fuel (SNF) fission product content predictions is established in a recent ORNL report where several SNF isotopic assays are analyzed; and (4) these data are then combined to establish in a conservative manner the fraction of the predicted total fission product absorption which can be guaranteed based on available experimental data
Fusion-Fission like studies from medium heavy to light compound systems
International Nuclear Information System (INIS)
It has been shown that for systems as light as ACN = 47 up to systems just above the Businaro Gallone point in the mass region of 100 to 110 the probability for a system to deexcite by the fission channel, is not negligible. As predicted, the asymmetrical separation becomes dominant when the ACN mass is decreasing but the symmetrical mode remains measurable. The ambiguities in the measured outgoing fragment distributions arise from the competition with IMF emissions as well as dynamical fission processes which depend strongly on the studied system. Fully relaxed DIC has also be used to interpret the results. I tried to show that precise checks on the behavior of two neighbouring systems as well as search for entrance channel effect and/or energy dependence bring evidence enough that the deexcitation of the compound nucleus can account for the symmetric and asymmetric fission channels as well as IMF emissions. This is strongly supported by different recent calculations all done in this frame. These all conclusions indicate also that the RLDM fails in the data interpretation. The strength of the fission channel depends strongly on the possibilities a system has to deexcite. For very light systems especially the number of open channels available determines directly the flux repartition between direct or compound processes and therefore very large differences in the general behaviour of two neighbouring systems can be observed. 15 figs
International Nuclear Information System (INIS)
Full text: LANL has a long-standing interest in selected threshold reaction cross sections, such as many of those that are defined in existing Dosimetry Cross Section files. Therefore LANL expects to play an active role in the testing of selected evaluated dosimetry cross section files that will appear in the IAEA's next generation Dosimetry file, the International Reactor Dosimetry Fission and Fusion File, IRDFF. A preliminary version of this file is currently available, designated IRDFF, v1.02. LANL has processed this file to create dosimetry class (.y) ace files for the continuous energy MCNP Monte Carlo transport code. Dosimetry class files differ from the traditional continuous energy (.c) class files in that they are NOT suitable for use in transport calculations ? rather they are used exclusively for accumulating tally information. As such, .y class files are simpler than .c files and the associated NJOY processing is also simpler. A generic NJOY input deck is given. As the original IRDFF source files are already defined to be at 300 K, and since .y class files do not require linearization and a uniform energy grid, the NJOY job consists of an optional call to MODER to extract the specific material of interest. A second MODER call creates a duplicate input file which is followed by a call to ACER (with iopt=3) to create the .y class output. A pre-release version of NJOY2012 was used to process these files which have been shared with the IAEA. Subsequently we learned that when NJOY99.393 is used the natGd and 238U files required additional memory. An NJOY99 patch file to accomplish this additional memory allocation has been created and will be publicly released shortly. In past years, LANL has operated a number of simple (both geometrically and materially) critical assemblies, including Godiva (a bare HEU sphere), Jezebel (a bare, predominately 239Pu, sphere) and various 'Flattop' assemblies. The Flattop cores consist of one of HEU, 239Pu or 233U surrounded
International Nuclear Information System (INIS)
Selected reactor physics and isotope balance characteristics of a fusion hybrid supported D-3He satellite nuclear energy system are formulated and investigated. The system consists of two types of reactors: a parent D-fueled fusion device and a number of smaller reactors optimized for D-3He fusion. The parent hybrid station breeds the helium-3 for the satellites and also breeds fissile fuel for an existing fission reactor economy. Various hybrid operational regimes are examined in order to determine favorable reactor Q values and effective fusion and fission efficiencies. A number of analytical correlations between power output, plasma energetics, blanket neutronics, breeding capacity, and energy conversion cycles are established and evaluated. Numerical examples of performance parameters such as fission-tofusion power, overall conversion efficiency, and the ratio of satellite to parent fusion power are presented. The range of reactor efficiencies is elucidated as affected by the internal plasma power balances. As an upper bound based on optimistic injection and direct conversion efficiencies, we find the D-3He satellite system power output attaining at best 1/3 of the parent fusion power
International Nuclear Information System (INIS)
The Conference was devoted to the challenges in the development of new materials for advanced fission, fusion and hybrid reactors. The topics discussed include fuels and materials research under the high neutron fluence; post-irradiation examination; development of radiation resistant structural materials utilizing fission research reactors; core materials development for the advanced fuel cycle initiative; qualification of structural materials for fission and fusion reactor systems; application of charged particle accelerators for radiation resistance investigations of fission and fusion structural materials; microstructure evolution in structural materials under irradiation; ion beams and ion accelerators
Activation calculation and environmental safety analysis for fusion experimental breeder (FEB)
International Nuclear Information System (INIS)
An activation calculation code FDKR and decay chain data library AFDCDLIB are used to calculate the radioactivity, decay heat, dose rate and biological hazard potential (BHP) form activation products, actinides and fission products in a Fusion Experiment Breeder (FEB). The code and library are introduced briefly, and calculation results and decay curves of related hazards after one year operation with 150 MW fusion power are given. The total radioactivity inventory, decay heat and BHP are 5.74 x 1020 Bq, 8.34 MW and 4.08 x 108 km3 of air, respectively, at shutdown. Results obtained show that the first wall of FEB can meet the nuclear waste disposal criteria for the NRC 10 CFR61 Class C after a few weeks from shutdown. The inventory of important actinides for the fuel reprocessing, such as 232U and 237Np were also calculated. It was shown that their concentrations do not excess the limit value of environmental safety required. (9 refs., 4 figs., 9 tabs.)
International Nuclear Information System (INIS)
This paper summarizes the current state of the art in science and technology of the safety concept for future fusion power plants (FPPs) and examines the transferability of the current nuclear fission regulation to the concepts of future fusion power plants. At the moment there exist only conceptual designs of future fusion power plants. The most detailed concepts with regards to safety aspects were found in the European Power Plant Conceptual Study (PPCS). The plant concepts discussed in the PPCS are based on magnetic confinement of the plasma. The safety concept of fusion power plants, which has been developed during the last decades, is based on the safety concepts of installations with radioactive inventories, especially nuclear fission power plants. It applies the concept of defence in depth. However, there are specific differences between the implementations of the safety concepts due to the physical and technological characteristics of fusion and fission. It is analysed whether for fusion a safety concept is required comparable to the one of fission. For this the consequences of a purely hypothetical release of large amounts of the radioactive inventory of a fusion power plant and a fission power plant are compared. In such an event the evacuation criterion outside the plant is exceeded by several orders of magnitude for a fission power plant. For a fusion power plant the expected radiological consequences are of the order of the evacuation criterion. Therefore, a safety concept is also necessary for fusion to guarantee the confinement of the radioactive inventory. The comparison between the safety concepts for fusion and fission shows that the fundamental safety function ''confinement of the radioactive materials'' can be transferred directly in a methodical way. For a fusion power plant this fundamental safety function is based on both, physical barriers as well as on active retention functions. After the termination of the fusion
Energy Technology Data Exchange (ETDEWEB)
Raeder, Juergen; Weller, Arthur; Wolf, Robert [Max-Planck-Institut fuer Plasmaphysik (IPP), Garching (Germany); Jin, Xue Zhou; Boccaccini, Lorenzo V.; Stieglitz, Robert; Carloni, Dario [Karlsruher Institute fuer Technologie (KIT), Eggenstein-Leopoldshafen (Germany); Pistner, Christoph [Oeko-Institut e.V., Darmstadt (Germany); Herb, Joachim [Gesellschaft fuer Anlagen- und Reaktorsicherheit, Koeln (Germany)
2016-01-15
This paper summarizes the current state of the art in science and technology of the safety concept for future fusion power plants (FPPs) and examines the transferability of the current nuclear fission regulation to the concepts of future fusion power plants. At the moment there exist only conceptual designs of future fusion power plants. The most detailed concepts with regards to safety aspects were found in the European Power Plant Conceptual Study (PPCS). The plant concepts discussed in the PPCS are based on magnetic confinement of the plasma. The safety concept of fusion power plants, which has been developed during the last decades, is based on the safety concepts of installations with radioactive inventories, especially nuclear fission power plants. It applies the concept of defence in depth. However, there are specific differences between the implementations of the safety concepts due to the physical and technological characteristics of fusion and fission. It is analysed whether for fusion a safety concept is required comparable to the one of fission. For this the consequences of a purely hypothetical release of large amounts of the radioactive inventory of a fusion power plant and a fission power plant are compared. In such an event the evacuation criterion outside the plant is exceeded by several orders of magnitude for a fission power plant. For a fusion power plant the expected radiological consequences are of the order of the evacuation criterion. Therefore, a safety concept is also necessary for fusion to guarantee the confinement of the radioactive inventory. The comparison between the safety concepts for fusion and fission shows that the fundamental safety function ''confinement of the radioactive materials'' can be transferred directly in a methodical way. For a fusion power plant this fundamental safety function is based on both, physical barriers as well as on active retention functions. After the termination of the fusion
Analytical model for fusion first-wall temperature calculations
International Nuclear Information System (INIS)
A primarily analytical thermal analysis model is presented which allows for calculation of temperatures in fusion reactor first walls. The model utilizes input quantities based on plasma physics calculations and couples a two-and-one-half-dimensional geometric analysis with a one-dimensional heat conduction analysis in determining temperature profiles over the surface of and within materials used to confine the plasma and vacuum. Given materials-related temperature limitations, methods are also provided for calculating maximum allowable wall power loadings. The results are primarily applicable to the steady-state operation of magnetic confinement devices such as tokamaks. 31 refs, 50 figs., 8 tabs
Methodology for fission product release calculations during an ACR-1000 end-fitting failure event
International Nuclear Information System (INIS)
The ACR-1000® reactor enhances and retains the proven features of the CANDU® design such as the concept of the horizontal fuel channel core. At each end of a fuel channel, there is an end-fitting incorporating a feeder connection through which pressurized coolant enters and leaves the fuel channel, where 12 fuel bundles are inserted. The safety analysis cases include postulated end-fitting failure events to assess the fission product releases from all fuel bundles which would be ejected out of the channel and oxidized in the air-steam environment under decay power. This paper presents the methodology used in assessing the fuel behaviour and the fission product releases during a postulated end-fitting failure in an ACR-1000 reactor. After the end-fitting failure, the 12 fuel bundles are ejected out of the channel and drop onto the fuelling machine vault floor. The fuel bundles are likely heavily damaged by impact and would break into small clusters of elements or fragments. To calculate the fission product releases from an individual fragment, the transient fuel temperature is numerically solved by differential heat equations; the air oxidation model is chosen for the event accordingly; and the fission product inventory and releases are estimated by computer codes ORIGEN-S, CATHENA, ELESTRES and SOURCE-IST. Finally, the total fission product releases from all fragments into containment are calculated. This methodology has been developed for ACR-1000 safety analysis, which is also applicable to CANDU. With the new methodology, the transient releases from up to 150 fission products can be estimated as detail as in fragment. In this paper, a sample calculation is also provided to show the application of the methodology in ACR-1000 safety analysis for end-fitting failure. (author)
Han, Jie
2014-01-01
We investigate time-dependent probability for a Brownian particle passing over the barrier to stay at a metastable potential pocket against escaping over the barrier. This is related to whole fusion-fission dynamical process and can be called the reverse Kramers problem. By the passing probability over the saddle point of inverse harmonic potential multiplying the exponential decay factor of a particle in the metastable potential, we present an approximate expression for the modified passing probability over the barrier, in which the effect of reflection boundary of potential is taken into account. Our analytical result and Langevin Monte-Carlo simulation show that the probability passing and against escaping over the barrier is a non-monotonous function of time and its maximal value is less than the stationary result of passing probability over the saddle point of inverse harmonic potential.
Energy Technology Data Exchange (ETDEWEB)
Cheng, E.T.; Mathews, D.R.
1979-09-01
The fusion-fission hybrid blanket proposed for the Tandem Mirror Hybrid Reactor employs thorium metal as the fertile material. Based on the ENDF/B-IV nuclear data, the /sup 233/U and tritium production rate and blanket energy multiplication averaged over the blanket lifetime of about 9 MW-yr/m/sup 2/ are 0.76 and 1.12 per D-T neutron and 4.8, respectively. At the time of the blanket discharge, the /sup 233/U enrichment in the thorium metal is about 3%. The thorium cross sections given by the ENDF/B-IV and V were reviewed, and the important partial cross sections such as (n,2n), (n,3n), and (n,..gamma..) were found to be known to +-10 to 20% in the respective energy range of interest. A sensitivity study showed that the /sup 233/U and tritium production rate and blanket energy multiplication are relatively sensitive to the thorium capture and fission cross section uncertainties. In order to predict the above parameters within +-1%, the Th(n,..gamma..) and Th(n,..nu..f) cross sections must be measured within about +-2% in the energy range 3 to 3000 keV and 13.5 to 15 MeV, respectively.
International Nuclear Information System (INIS)
The fusion-fission hybrid blanket proposed for the Tandem Mirror Hybrid Reactor employs thorium metal as the fertile material. Based on the ENDF/B-IV nuclear data, the 233U and tritium production rate and blanket energy multiplication averaged over the blanket lifetime of about 9 MW-yr/m2 are 0.76 and 1.12 per D-T neutron and 4.8, respectively. At the time of the blanket discharge, the 233U enrichment in the thorium metal is about 3%. The thorium cross sections given by the ENDF/B-IV and V were reviewed, and the important partial cross sections such as (n,2n), (n,3n), and (n,γ) were found to be known to +-10 to 20% in the respective energy range of interest. A sensitivity study showed that the 233U and tritium production rate and blanket energy multiplication are relatively sensitive to the thorium capture and fission cross section uncertainties. In order to predict the above parameters within +-1%, the Th(n,γ) and Th(n,νf) cross sections must be measured within about +-2% in the energy range 3 to 3000 keV and 13.5 to 15 MeV, respectively
Mitochondrial fission and fusion in astrocytes: a new pathway towards senescence
Directory of Open Access Journals (Sweden)
Sonia Luz Albarracin
2015-02-01
Full Text Available Astrocytes are highly specialized cells that can maintain the integrity of the synapse, facilitate nutrition and trophic support to neurons, and regulate metabolic coupling between neurons and glia. However, astrocytes are involved in resolving different types of injuries and in aging processes in the brain. Senescence has also been reported in the brain, and senescence-associated loss of astrocyte function is linked to neuronal dysfunction in age-related neurodegenerative diseases such as Alzheimer’s disease and Parkinson's disease. For example, astrocyte senescence per se inhibits synapse maturation and affects synaptic transmission. In response to the cell’s bio-energetic state, mitochondria continuously undergo structural remodeling through fission and fusion processes. These tightly regulated events are believed to be involved in many cellular events such as apoptosis, senescence, and age-related diseases. Although, little is known about the age-related changes that occur in astrocytes and if these cells are able to generate a senescent phenotype mediated by mitochondria, in the present study we evaluated the involvement of mitochondrial remodeling in the senescence process of rat astrocytes in vitro. The results obtained showed that when comparing cells at population doubling two (PD2 with cells at population doubling ten (PD10 there is a significant increase in the activity of the senescence-associated β-galactosidase marker in PD10 cells. In addition, PD10 cells had increased mitochondrial volume, decreased superoxide production, and decreased mitochondrial membrane potential. Protein characterization evidenced changes in the balance between mitochondrial fission and fusion proteins. Collectively, our results demonstrated a senescent-astrocyte phenotype at PD10, which is associated with metabolic and mitochondrial phenotype changes.
Neutron and photon transport calculations in fusion system. 2
Energy Technology Data Exchange (ETDEWEB)
Sato, Satoshi [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment
1998-03-01
On the application of MCNP to the neutron and {gamma}-ray transport calculations for fusion reactor system, the wide range design calculation has been carried out in the engineering design activities for the international thermonuclear fusion experimental reactor (ITER) being developed jointly by Japan, USA, EU and Russia. As the objects of shielding calculation for fusion reactors, there are the assessment of dose equivalent rate for living body shielding and the assessment of the nuclear response for the soundness of in-core structures. In the case that the detailed analysis of complicated three-dimensional shapes is required, the assessment using MCNP has been carried out. Also when the nuclear response of peripheral equipment due to the gap streaming between blanket modules is evaluated with good accuracy, the calculation with MCNP has been carried out. The analyses of the shieldings for blanket modules and NBI port are explained, and the examples of the results of analyses are shown. In the blanket modules, there are penetrating holes and continuous gap. In the case of the NBI port, shielding plug cannot be installed. These facts necessitate the MCNP analysis with high accuracy. (K.I.)
Competition between fusion-fission and quasifission processes in the 30Si+182,184,186W systems
International Nuclear Information System (INIS)
The dynamics of fusion-fission processes in heavy-ion collisions has been extensively investigated, both theoretically and experimentally, in recent years. The time evolution of the composite system formed after interaction, and parameters on which the dynamics depends etc., are still not fully understood. Studies on dynamical processes in heavy ion collisions at the near-Coulomb-barrier energies have shown that complete fusion does not occur immediately in the case of massive nuclei collisions. Among various competing processes, quasifission (QF) is the dominant non-compound nuclear process. We, here report the di-nuclear system (DNS) model predictions of capture, fusion and quasi fission cross-sections for 30Si+182,184,186W systems in the centre-of-mass energy range 113 MeV to 163 MeV
Sonzogni, A. A.; McCutchan, E. A.; Johnson, T. D.; Dimitriou, P.
2016-04-01
Fission yields form an integral part of the prediction of antineutrino spectra generated by nuclear reactors, but little attention has been paid to the quality and reliability of the data used in current calculations. Following a critical review of the thermal and fast ENDF/B-VII.1 235U 235 fission yields, deficiencies are identified and improved yields are obtained, based on corrections of erroneous yields, consistency between decay and fission yield data, and updated isomeric ratios. These corrected yields are used to calculate antineutrino spectra using the summation method. An anomalous value for the thermal fission yield of 86Ge generates an excess of antineutrinos at 5-7 MeV, a feature which is no longer present when the corrected yields are used. Thermal spectra calculated with two distinct fission yield libraries (corrected ENDF/B and JEFF) differ by up to 6% in the 0-7 MeV energy window, allowing for a basic estimate of the uncertainty involved in the fission yield component of summation calculations. Finally, the fast neutron antineutrino spectrum is calculated, which at the moment can only be obtained with the summation method and may be relevant for short baseline reactor experiments using highly enriched uranium fuel.
Sonzogni, A A; McCutchan, E A; Johnson, T D; Dimitriou, P
2016-04-01
Fission yields form an integral part of the prediction of antineutrino spectra generated by nuclear reactors, but little attention has been paid to the quality and reliability of the data used in current calculations. Following a critical review of the thermal and fast ENDF/B-VII.1 ^{235}U fission yields, deficiencies are identified and improved yields are obtained, based on corrections of erroneous yields, consistency between decay and fission yield data, and updated isomeric ratios. These corrected yields are used to calculate antineutrino spectra using the summation method. An anomalous value for the thermal fission yield of ^{86}Ge generates an excess of antineutrinos at 5-7 MeV, a feature which is no longer present when the corrected yields are used. Thermal spectra calculated with two distinct fission yield libraries (corrected ENDF/B and JEFF) differ by up to 6% in the 0-7 MeV energy window, allowing for a basic estimate of the uncertainty involved in the fission yield component of summation calculations. Finally, the fast neutron antineutrino spectrum is calculated, which at the moment can only be obtained with the summation method and may be relevant for short baseline reactor experiments using highly enriched uranium fuel. PMID:27081973
Fission gas activities in the fuel-to-clad gap calculated with the code FUROM
International Nuclear Information System (INIS)
The fuel behaviour code FUROM (FUel ROd Model) has been in use and under improvement for several years at the Hungarian Academy of Sciences KFKI Atomic Energy Research Institute. Several new features are added to it each year. In the present paper an extended fission gas release model is introduced. This model is suitable for the calculation of the release of not only stable but also radioactive isotopes. Code calculations are compared to international results. (authors)
Measurement and calculation of the 233Pa fission cross-section for advanced fuel cycles
International Nuclear Information System (INIS)
The energy dependence of the neutron-induced fission cross-section of 233Pa has been measured directly for the first time from the fission threshold up to 8.5 MeV. This fission cross-section is a key ingredient in feasibility studies on fast reactors and accelerator driven systems based on the Th-U fuel cycle. The results are at strong variance with the existing evaluations. The new experimental data give lower cross-section values and resolve the question about the threshold energy. Additionally a new theoretical calculation of the reaction cross-section has been performed with the statistical model code STATIS, showing a very good agreement with the experimental data. (authors)
Siegel, Edward
2011-04-01
Numbers: primality/indivisibility/non-factorization versus compositeness/divisibility /factor-ization, often in tandem but not always, provocatively close analogy to nuclear-physics: (2 + 1)=(fusion)=3; (3+1)=(fission)=4[=2 x 2]; (4+1)=(fusion)=5; (5+1)=(fission)=6[=2 x 3]; (6 + 1)=(fusion)=7; (7+1)=(fission)=8[= 2 x 4 = 2 x 2 x 2]; (8 + 1) =(non: fission nor fusion)= 9[=3 x 3]; then ONLY composites' Islands of fusion-INstability: 8, 9, 10; then 14, 15, 16,... Could inter-digit Feshbach-resonances exist??? Applications to: quantum-information and computing non-Shore factorization, millennium-problem Riemann-hypotheses physics-proof as numbers/digits Goodkin Bose-Einstein Condensation intersection with graph-theory ``short-cut'' method: Rayleigh(1870)-Polya(1922)-``Anderson'' (1958)-localization, Goldbach-conjecture, financial auditing/accounting as quantum-statistical-physics;... abound!!!
Siegel, Edward
2011-10-01
Numbers: primality/indivisibility/non-factorization versus compositeness/divisibility /factor-ization, often in tandem but not always, provocatively close analogy to nuclear-physics: (2 + 1)=(fusion)=3; (3+1)=(fission)=4[=2 × 2]; (4+1)=(fusion)=5; (5 +1)=(fission)=6[=2 × 3]; (6 + 1)=(fusion)=7; (7+1)=(fission)=8[= 2 × 4 = 2 × 2 × 2]; (8 + 1) =(non: fission nor fusion)= 9[=3 × 3]; then ONLY composites' Islands of fusion-INstability: 8, 9, 10; then 14, 15, 16,... Could inter-digit Feshbach-resonances exist??? Applications to: quantum-information/computing non-Shore factorization, millennium-problem Riemann-hypotheses proof as Goodkin BEC intersection with graph-theory ``short-cut'' method: Rayleigh(1870)-Polya(1922)-``Anderson'' (1958)-localization, Goldbach-conjecture, financial auditing/accounting as quantum-statistical-physics;... abound!!!
Neutronic performance of a fusion-fission hybrid reactor designed for fuel enrichment for LWRs
International Nuclear Information System (INIS)
In this study, the breeding performance of a fission hybrid reactor was analyzed to provide fissile fuel for Light Water Reactors (LWR) as an alternative to the current methods of gas diffusion and gas centrifuge. LWR fuel rods containing UO2 or ThO2 fertile material were located in the fuel zone of the blanket and helium gas or Flibe (Li2BeF4) fluid was used as coolant. As a result of the analysis, according to fusion driver (D,T and D,D) and the type of coolant the enrichment of 3%-4% were achieved for operation periods of 12 and 36 months in case of fuel rods containing UO2, respectively and for operation periods of 18 and 48 months in case of fuel rods containing ThO2, respectively. Depending on the type of fusion driver, coolant and fertile fuel, varying enrichments of between 3% and 8.9% were achieved during operation period of four years
Thermal Fission Rate Calculated Numerically by Particles Multi-passing over Saddle Point
Institute of Scientific and Technical Information of China (English)
LIU Ling; BAO Jing-Dong
2004-01-01
Langevin simulation of the particles multi-passing over the saddle point is proposed to calculate thermal fission rate. Due to finite friction and the corresponding thermal fluctuation, a backstreaming exists in the process of the particle descent from the saddle to the scission. This leads to that the diffusion behind the saddle point has influence upon the stationary flow across the saddle point. A dynamical correction factor, as a ratio of the flows of multi- and firstoverpassing the saddle point, is evaluated analytically. The results show that the fission rate calculated by the particles multi-passing over the saddle point is lower than the one calculated by the particle firstly passing over the saddle point,and the former approaches the results at the scission point.
Measured and calculated fission-product poisoning in neutron-irradiated uranium-233
International Nuclear Information System (INIS)
Samples of 233U and of natural thorium have been irradiated in high neutron-flux facilities, in both soft and hard neutron spectra, and for both short and long exposure times. Included are exposures resulting in depletions of more than 90 percent of the 233U in the fissile material and burnups of more than 30,000 MWd/MT in the fertile material. Fission-product poison cross sections in two energy groups (thermal and epithermal) exhibit differences between measurement and calculation that are believed to be attributable to a lack of adequate information on important fission products in the literature. Experimental results for transient absorbers in irradiated 233U give at least 20,000 b for the neutron absorption resonance integral of 149Pm. This is a factor of 15 higher than that obtained by a 1/v extrapolation of the thermal cross sections. For transient 135Xe, the measured absorption is 7.5 percent higher than that calculated using ENDF/B-IV data. Information is also provided concerning such matters as fission yields and neutron absorption of neodymium isotopes, the existence of significant transient fission-product poisons other than 135Xe and 149Sm, and the shielding of 233U by 232Th. Such shielding suggests the need for a change in the energy dependence of the 232Th thermal-neutron cross section
International Nuclear Information System (INIS)
In the design of the reactor room for a fusion reactor, the cost of the room strongly depends on the thickness of the roof because the area of the roof is generally large. The roof thickness is mostly determined by the requirement to reduce the skyshine dose rate level at the site boundary below the assigned value. Therefore the accurate evaluation of the skyshine dose becomes important for the design of the reactor room. Skyshine dose for a D-T fusion reactor has been evaluated by a number of researchers but the agreement is not so good. In this report, the first collision source is used with two-dimensional SN transport method to form DOT3.5-GRTUNCL-DOT3.5 coupled calculation flow. The validity of the methodology was first shown by calculating the skyshine dose from a 14 MeV neutron source and comparing the calculated results with the measured results. This methodology was then used to calculate the skyshine dose for the Fusion Experimental Reactor (FER). The calculated results were compared with those from several other methods to clarify the mutual difference. (author)
A simple method for evaluation of uncertainties in fission product decay heat summation calculations
International Nuclear Information System (INIS)
The present precision of nuclear data for the aggregate decay heat evaluation is analyzed quantitatively for 50 fissioning systems. In the practical calculation, a simple approximate method is proposed in order to avoid complication of the calculation and to point out easily the main causal nuclei of the uncertainties in decay heat calculations. As for the independent yield, the correlation among the values is taken into account. For this evaluation, nuclear data and their uncertainty data are taken from ENDF/B-VI nuclear data library. (author)
Activation calculation and waste management for a fusion experimental breeder, FEB-E
International Nuclear Information System (INIS)
The engineering outline design of the fusion experimental breeder, FEB-E is reported briefly. Using an activation calculation code FDKR and its associated data library AF-DCDLIB to calculate the radioactivity, decay heat, waste disposal rating and biological hazard potential from activation products, actinides and fission products in the FEB-E. The codes and libraries used in calculation are introduced briefly, and calculation results and decay curves of related hazards after the shutdown of one-year operation of the FEB-E are given. The activation features of five candidate structural materials were also evaluated for FEB-E design. Detailed calculation and analyses of waste disposal rating and remote maintenance rating for all long-lived radionuclides were performed to identify the safety, environmental and radioactive waste characteristics of the FEB-E design. Results obtained show that the total radioactivity inventory, decay heat and BHP at shutdown are 5.74x1013MBq, 8.34 MW and 4.08x108km3 of air for 316SS structure material, respectively. The inventory of actinides important for the fuel reprocessing, such as 232U and 237Np was also investigated. It was shown that their low concentrations in FEB-E appear to be manageable
Nuclear group constant set FUSION-J3 for fusion reactor nuclear calculations based on JENDL-3
International Nuclear Information System (INIS)
Based on evaluated nuclear data file JENDL-3, published in April 1990, we produced a nuclear group constant set 'FUSION-J3' for fusion reactor nuclear calculation by ANISN code instead of GICX40 produced in 1977. The set FUSION-J3 is the coupled group constant set with neutron 125 and gamma-ray 40 group structure, and has the maximum order of 5 as Legendre expansion in scattering cross section. Forty nuclides included in FUSION-J3 can be used in fusion reactor nuclear calculations. Considering mobility in two-dimensional calculations and fixed group structure in induced activity calculation code system as the GICX40 structure, we composed also FUSION-40 group constant set with neutron 42 group and gamma-ray 21 group structure. The set FUSION-40 includes the same maximum order of the Legendre expansion and the same nuclides as FUSION-J3. From the results in experimental analysis and benchmark calculations, it became proved that JENDL-3 is at higher level of accuracy than ENDF/B-IV and -V. The set FUSION-J3 can be clear applicable to fusion reactor nuclear calculations. (author)
Calculation of the fast multiplication factor by the fission matrix method
International Nuclear Information System (INIS)
A variation of the Monte Carlo method to calculate an effective breeding factor of a nuclear reactor is described. The evaluation procedure of reactivity perturbations by the Monte Carlo method in the first order perturbation theory is considered. The method consists in reducing an integral neutron transport equation to a set of linear algebraic equations. The coefficients of this set are elements of a fission matrix. The fission matrix being a Grin function of the neutron transport equation, is evaluated by the Monte Carlo method. In the program realizing the suggested algorithm, the game for initial neutron energy of a fission spectrum and then for the region of neutron birth, ΔVsub(f)sup(i)has been played in proportion to the product of Σsub(f)sup(i)ΔVsub(f)sup(i), where Σsub(f)sup(i) is a macroscopic cross section in the region numbered at the birth energy. Further iterations of a space distribution of neutrons in the system are performed by the generation method. In the adopted scheme of simulation of neutron histories the emission of secondary neutrons is controlled by weights; it occurs at every collision and not only in the end on the history. The breeding factor is calculated simultaneously with the space distribution of neutron worth in the system relative to the fission process and neutron flux. Efficiency of the described procedure has been tested on the calculation of the breeding factor for the Godiva assembly, simulating a fast reactor with a hard spectrum. A high accuracy of calculations at moderate number of zones in the core and reasonable statistics has been stated
International Nuclear Information System (INIS)
Improving the prediction of radiation parameters and reliability of fuel behaviour under different irradiation modes is particularly relevant for new fuel compositions, including recycled nuclear fuel. For fast reactors there is a strong dependence of nuclide accumulations on the nuclear data libraries. The effect of fission yield libraries on irradiated fuel is studied in MONTEBURNS-MCNP5-ORIGEN2 calculations of sodium fast reactors. Fission yield libraries are generated for sodium fast reactors with MOX fuel, using ENDF/B-VII.0, JEFF3.1, original library FY-Koldobsky, and GEFY 3.3 as sources. The transport libraries are generated from ENDF/B-VII.0 and JEFF-3.1. Analysis of irradiated MOX fuel using different fission yield libraries demonstrates the considerable spread in concentrations of fission products. The discrepancies in concentrations of inert gases being ∼25%, up to 5 times for stable and long-life nuclides, and up to 10 orders of magnitude for short-lived nuclides. (authors)
XEUS: Exploratory Energy Utilization Systemic s for Fission Fusion Hybrid Application
International Nuclear Information System (INIS)
World energy outlook requires environmental friendliness, sustain ability and improved economic feasibility. The Exploratory Energy Utilization Systemic s (XEUS) is being developed at the Seoul National University (SNU) to satisfy these demands. Generation IV (Gen IV) and fusion reactors are considered as candidates for the primary system. Battery Omnibus Reactor Integral System (BORIS) is a liquid-metal cooled fast reactor which is one of the Gen IV concepts. Fusion Engineering Lifetime Integral Explorer (FELIX) is a fusion demonstration reactor for power generation. These two concepts are considered as dominant options for future nuclear energy source from the environmental, commercial and nonproliferation points of view. XEUS may as well be applied to the fusion-fission hybrid system. The system code is being developed to analyze the steady state and transient behavior of the primary system. Compact and high efficiency heat exchangers are designed in the Loop Energy Exchanger Integral System (LEXIS). Modular Optimized Brayton Integral System (MOBIS) incorporates a Brayton cycle with supercritical fluid to achieve high power conversion ratio. The high volumetric energy density of the Brayton cycle enables designers to reduce the size and eventually the cost of the system when compared with that of the Rankine cycle. MOBIS is home to heat exchangers and turbo machineries. The advanced shell-and-tube or printed circuit heat exchanger is considered as heat transfer components to reduce size of the system. The supercritical fluid driven turbines and compressor are designed to achieve higher component efficiency. Thermo hydrodynamic characteristics of each component in MOBIS are demonstrated utilizing computational fluid dynamics software CFXR. Another key contributor to the reduction of capital costs per unit energy has to do with manufacturing and assembly processes that streamline plant construction by minimizing construction work and time. In a three
Indian Academy of Sciences (India)
Hadi Eslamizadeh
2015-12-01
The anisotropy of fission fragment angular distribution, evaporation residue crosssection and the fission cross-section were calculated for 197Tl formed in 16O+181Ta reactions in the framework of the modified statistical model and the results were compared with the experimental data. The effects of temperature and projection of spin about the symmetry axis have been considered for calculating potential energy surfaces and fission widths. It was shown that in the framework of the modified statistical model, by choosing appropriate values for the temperature coefficient of the effective potential, , and scaling factor of the fission-barrier height, s, one can satisfactorily reproduce the above-mentioned experimental data. It was also shown that the appropriate values of these parameters for 197Tl are = 0.0185 ± 0.0050 MeV-2 and s = 1.0006 ± 0.0020.
International Nuclear Information System (INIS)
The anisotropy of fission fragment angular distribution, evaporation residue cross-section and the fission cross-section were calculated for 197Tl formed in 16O+181Ta reactions in the framework of the modified statistical model and the results were compared with the experimental data. The effects of temperature and projection of spin about the symmetry axis K have been considered for calculating potential energy surfaces and fission widths. It was shown that in the framework of the modified statistical model, by choosing appropriate values for the temperature coefficient of the effective potential, α , and scaling factor of the fission-barrier height, rs, one can satisfactorily reproduce the above-mentioned experimental data. It was also shown that the appropriate values of these parameters for 197Tl are α = 0.0185 ± 0.0050 MeV-2 and rs = 1.0006 ± 0.0020. (author)
Feasibility study of a hybrid subcritical fission system driven by Plasma-Focus fusion neutrons
International Nuclear Information System (INIS)
Highlights: • A model of a subcritical cascade driven by a Plasma Focus device is presented. • Optimum parameters to achieve given levels of neutron amplification are produced. • Monte Carlo calculations for spherical shells of enriched Uranium were performed. • Break-even conditions can be achieved with Plasma Focus of tens of kJ. - Abstract: A feasibility analysis of a hybrid fusion–fission system consisting of a two-stage spherical subcritical cascade driven by a Plasma Focus device is presented. The analysis is based on the one-group neutron diffusion equation, which was appropriately cast to assess the neutronic amplification of a spherical configuration. A design chart was produced to estimate the optimum dimensions of the fissile shells required to achieve different levels of neutron amplification. It is found that cascades driven by Plasma Focus of tens of kJ are feasible. The results were corroborated by means of Monte Carlo calculations
International Nuclear Information System (INIS)
In nuclear technology a lot of experience has been accumulated meanwhile from reactor programmes for ferritic alloys, austenitic steels and Ni-based alloys as main component materials during R and D, design, construction and operation. Generally materials are a key issue for a safe and reliable operation of -NPPs. Many grades investigated are of interest for the design of GenIVs and fusion reactors. Synergisms of materials, material technologies, mechanical data, corrosion and other topics -for the qualification of materials for nuclear systems are generally discussed and information on a qualification procedure is compiled. Also some lessons learned from fabrication, test programmes or operation of NPPs are provided. A special problem is the fusion system because a final validation for alloy performance in the long term will need irradiation under realistic -fusion condition anticipated in a high-energetic, fusion-specific intense neutron source such as (IFMIF), the International Fusion Materials Irradiation Facility. (author)
Scission-point configurations in ternary fission of 252Cf from trajectory calculations
International Nuclear Information System (INIS)
Trajectory calculations have been carried out in a three-point- charge model for the case of spontaneous ternary fission of 252Cf with a view to obtain the initial parameters characterizing the scission configuration. Without any a priori assumptions regarding the distribution of the points of emission of the α particle and the fragment velocity at the time of scission, the values of the initial parameters were obtained by fitting the observed energy distributions by making use of the method of multivariate analysis. It was found that there exist two points of α particle emission, nearer to either of the two fragments and off the axis joining the fragment centers, which reproduce the experijmental distributions equally well. This result does not support the often made assumption that the point of α particle emission coincides with the potential energy minimum on the line joining the fragment centers. With the initial parameters thus obtained, an inverse Monte Carlo calculation was carried out to obtain various correlations between the final values of the energy and the angle of emission of the α particle and the fission fragment kinetic energy. The calculated results agree well with the experiments. The implication of present results on the emission mechanism of the α particle in ternary fission is discussed
International Nuclear Information System (INIS)
In addition to the traditional fission reactor research, fusion R and D activities are becoming of interest also to nuclear fission power development. There is renewed interest in utilizing fusion neutrons, Heavy Liquid Metals, and molten salts for innovative systems (energy production and transmutation). Indeed, for nuclear power development to become sustainable as a long-term energy option, innovative fuel cycle and reactor technologies will have to be developed to solve the problems of resource utilization and long-lived radioactive waste management. In this context Member States clearly expressed the need for comparative assessments of various transmutation reactors. Both the fusion and fission communities are currently investigating the potential of innovative reactor and fuel cycle strategies that include a fusion/fission system. The attention is mainly focused on substantiating the potential advantages of such systems: utilization and transmutation of actinides and long-lived fission products, intrinsic safety features, enhanced proliferation resistance, and fuel breeding capabilities. An important aspect of the ongoing activities is the comparison with the accelerator driven subcritical system (spallation neutron source), which is the other main option for producing excess neutrons. Apart from comparative assessments, knowledge preservation is another subject of interest to the Member States: the goal, applied to fusion/fission systems, is to review the status of, and to produce a 'compendium' of past and present achievements in this area
International Nuclear Information System (INIS)
The effects of fuel cycle parameters on nuclear waste environmental impact are analyzed for an advanced system that includes a Fusion-Fission Hybrid reactor. The system aims at reduction of the long-term radiotoxicity of waste by transmuting highly radiotoxic transuranics. However, the radiological risk of the system is measured by annual doses to the public, which are controlled by reactor operations, fuel cycle processes, waste treatment processes, and design of geological repositories. In this study, the waste environmental impact for a fuel cycle with a Fusion-Fission transmutation is analyzed as a function of three different parameters: burn-up, recovery efficiency and waste form durability for two different geological repositories, one with low actinide solubility and the other with high solubility. It is found that burn-up and recovery efficiency effects on environmental impact strongly depend on repository conditions, while the most influential parameter is found to be the durability of the waste form. (author)
International Nuclear Information System (INIS)
Research highlights: → Chemical inhibition of fission protein Drp1 leads to mitochondrial fusion. → Increased fusion stimulates molecular changes in mitochondrial fusion protein OPA1. → Proteolysis of larger isoforms, new synthesis and ubiquitination of OPA1 occur. → Loss of mitochondrial tubular rigidity and disorganization of cristae. → Generation of large swollen dysfunctional mitochondria. -- Abstract: We showed earlier that 15 deoxy Δ12,14 prostaglandin J2 (15d-PGJ2) inactivates Drp1 and induces mitochondrial fusion . However, prolonged incubation of cells with 15d-PGJ2 resulted in remodeling of fused mitochondria into large swollen mitochondria with irregular cristae structure. While initial fusion of mitochondria by 15d-PGJ2 required the presence of both outer (Mfn1 and Mfn2) and inner (OPA1) mitochondrial membrane fusion proteins, later mitochondrial changes involved increased degradation of the fusion protein OPA1 and ubiquitination of newly synthesized OPA1 along with decreased expression of Mfn1 and Mfn2, which likely contributed to the loss of tubular rigidity, disorganization of cristae, and formation of large swollen degenerated dysfunctional mitochondria. Similar to inhibition of Drp1 by 15d-PGJ2, decreased expression of fission protein Drp1 by siRNA also resulted in the loss of fusion proteins. Prevention of 15d-PGJ2 induced mitochondrial elongation by thiol antioxidants prevented not only loss of OPA1 isoforms but also its ubiquitination. These findings provide novel insights into unforeseen complexity of molecular events that modulate mitochondrial plasticity.
International Nuclear Information System (INIS)
Plasma size and other basic performance parameters for 1000-MW(electric) power production are calculated with the blanket energy multiplication factor, the M value, as a parameter. The calculational model is base don the International Thermonuclear Experimental Reactor (ITER) physics design guidelines and includes overall plant power flow. Plasma size decreases as the M value increases. However, the improvement in the plasma compactness and other basic performance parameters, such as the total plant power efficiency, becomes saturated above the M = 5 to 7 range. THus, a value in the M = 5 to 7 range is a reasonable choice for 1000-MW(electric) hybrids. Typical plasma parameters for 1000-MW(electric) hybrids with a value of M = 7 are a major radius of R = 5.2 m, minor radius of a = 1.7 m, plasma current of Ip = 15 MA, and toroidal field on the axis of Bo = 5 T. The concept of a thermal fission blanket that uses light water as a coolant is selected as an attractive candidate for electricity-producing hybrids. An optimization study is carried out for this blanket concept. The result shows that a compact, simple structure with a uniform fuel composition for the fissile region is sufficient to obtain optimal conditions for suppressing the thermal power increase caused by fuel burnup. The maximum increase in the thermal power is +3.2%. The M value estimated from the neutronics calculations is ∼7.0, which is confirmed to be compatible with the plasma requirement. These studies show that it is possible to use a tokamak fusion core with design requirements similar to those of ITER for a 1000-MW(electric) power reactor that uses existing thermal reactor technology for the blanket. 30 refs., 22 figs., 4 tabs
The fusion-fission process in the reaction {sup 34}S+{sup 186}W near the interaction barrier
Energy Technology Data Exchange (ETDEWEB)
Harca, I. M. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, (FLNR JINR) Dubna, Russia and Faculty of Physics, University of Bucharest - P.O. Box MG 11, RO 77125, Bucharest-Magurele (Romania); Dmitriev, S.; Itkis, J.; Kozulin, E. M.; Knyazheva, G.; Loktev, T.; Novikov, K. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, (FLNR JINR) Dubna (Russian Federation); Azaiez, F.; Gottardo, A.; Matea, I.; Verney, D. [IPN, CNRS/IN2P3, Univ. Paris-Sud, 91405 Orsay (France); Chubarian, G. [Cyclotron Institute, Texas A and M University, College Station, TX 77843-3366 (United States); Hanappe, F. [Universite Libre de Bruxelles (ULB), Bruxelles (Belgium); Piot, J.; Schmitt, C. [GANIL, CEA/DSM-CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); Trzaska, W. H. [Accelerator Laboratory of University of Jyväskylä (JYFL), Jyväskylä (Finland); Vardaci, E. [Dipartamento di Scienze Fisiche and INFN (INFN-Na), Napoli (Italy)
2015-02-24
The reaction {sup 34}S+{sup 186}W at E{sub lab}=160 MeV was investigated with the aim of diving into the features of the fusion-fission process. Gamma rays in coincidence with binary reaction fragments were measured using the high efficiency gamma-ray spectrometer ORGAM at the TANDEM Accelerator facility of I.P.N., Orsay, and the time-of-flight spectrometer for fission fragments (FF) registration CORSET of the Flerov Laboratory of Nuclear Reactions (FLNR), Dubna. The coupling of the ORGAM and CORSET setups offers the unique opportunity of extracting details for characterizing the fusion-fission process and gives information regarding production of neutron-rich heavy nuclei. The FF–γ coincidence method is of better use then the γ – γ coincidence method when dealing with low statistic measurements and also offers the opportunity to precisely correct the Dopler shift for in-flight emitted gamma rays. Evidence of symmetric and asymmetric fission modes were observed in the mass and TKE distributions, occurring due to shell effects in the fragments. Coincident measurements allow for discrimination between the gamma rays by accepting a specific range within the mass distribution of the reaction products. Details regarding the experimental setup, methods of processing the acquisitioned data and preliminary results are presented.
International Nuclear Information System (INIS)
V-4Cr-4Ti, F82H, Ni and Cu were irradiated with fission and fusion neutrons at room temperature and 473 K. Defect structures were analyzed and compared using positron annihilation lifetime measurement, and microstructural evolution was discussed. The mean lifetime of positrons (the total amount of residual defects) increased with the irradiation dose. The effect of cascade impact was detected in Ni at room temperature. The size and the number of vacancy clusters were not affected by the displacement rate in the fission neutron irradiation at 473 K for the metals studied. The vacancy clusters were not formed in V-4Cr-4Ti irradiated at 473 K in the range of 10-6-10-3 dpa. In F82H irradiated at 473 K, the defect evolution was prevented by pre-existing defects. The mean lifetime of positrons in fission neutron irradiation was longer than that in fusion neutron irradiation in V-4Cr-4Ti at 473 K. It was interpreted that more closely situated subcascades were formed in the fusion neutron irradiation and subcascades interacted with each other, and consequently the vacancy clusters did not grow larger.
International Nuclear Information System (INIS)
The dynamical cluster-decay model (DCM), with deformations and orientation degrees of freedom of the incoming nuclei and of outgoing fragments included, is used to study the excitation functions of the "equatorial" compact hot fusion reaction 244Pu+48Ca→292114* (compact orientation angle θc=90° for 244Pu). Considering the higher multipole deformations up to hexadecapole deformation β4 and configurations with "compact" orientation θc, the model is shown to give a good description of the measured individual light-particle decay channels σxn, here x=3, 4 and 5, and other decay channels, the fusion-fission σff and quasi-fission σqf (equivalently, capture σcap) with in one parameter fitting, the neck length ΔR. The quasi-fission is also considered as a cold process with an elongated "polar" configuration. The xn-channel cross-sections for collisions between nuclei with static deformations at their respective compact orientations are shown to be much more than for the case of the nuclei taken to be spherical, signifying the increase in fusion threshold for an intermediate hot fusion reaction to be associated with the static deformation of the target nucleus and its orientation at the point of collision in its path toward the (spherical) compound nucleus. The shell effects in both the potential and kinetic energy (the mass parameters) terms of the Hamiltonian are shown to be important. The free parameter ΔR of the model is shown to depend strongly on limiting angular momentum, which in turn depends on the use of sticking or non-sticking moment of inertia for angular momentum effects. For the sticking moment of inertia, the evaporation residue (neutron emission) is shown to occur almost promptly (largest ΔR), followed by the competing (hot/cold) quasi-fission and ending finally with fusion-fission of hot compound nucleus. Different ΔR's (equivalently, relative separations) for the three processes means to predict that the processes ER, ff and qf happen
Fission-fusion dynamics, behavioral flexibility, and inhibitory control in primates.
Amici, Federica; Aureli, Filippo; Call, Josep
2008-09-23
The Machiavellian Intelligence or Social Brain Hypothesis explains the evolution of increased brain size as mainly driven by living in complex organized social systems in which individuals represent "moving targets" who can adopt multiple strategies to respond to one another. Frequently splitting and merging in subgroups of variable composition (fission-fusion or FF dynamics) has been proposed as one aspect of social complexity ( compare with) that may be associated with an enhancement of cognitive skills like inhibition, which allows the suppression of prepotent but ineffective responses in a changing social environment. We compared the performance of primates experiencing high levels of FF dynamics (chimpanzees, bonobos, orangutans, and spider monkeys) to that of species living in more cohesive groups (gorillas, capuchin monkeys, and long-tailed macaques) on five inhibition tasks. Testing species differing in diet, phylogenetic relatedness, and levels of FF dynamics allowed us to contrast ecological, phylogenetic, and socioecological explanations for interspecific differences. Spider monkeys performed at levels comparable to chimpanzees, bonobos, and orangutans, and better than gorillas. A two-cluster analysis grouped all species with higher levels of FF dynamics together. These findings confirmed that enhanced inhibitory skills are positively associated with FF dynamics, more than to phylogenetic relations or feeding ecology. PMID:18804375
Quasiﬁssion and Fusion-Fission Competition in 32S + 184W Reaction
Directory of Open Access Journals (Sweden)
Manganaro M.
2011-10-01
Full Text Available The angular distribution of ﬁssion fragments for the 32S+184W reaction at center-of-mass energies of 118.8, 123.1, 127.3, 131.5, 135.8, 141.1 and 144.4 MeV were measured. The experimental ﬁssion excitation function is obtained. The fragment angular anisotropy is found by extrapolating the ﬁssion angular distributions. The measured ﬁssion cross sections are decomposed into fusion-ﬁssion, quasiﬁssion and fast-ﬁssion contributions by the dinuclear system model. The total evaporation residue and fusion-ﬁssion excitation functions are calculated in the framework of the advanced statistical model.
Barber, Duncan Henry
During some postulated accidents at nuclear power stations, fuel cooling may be impaired. In such cases, the fuel heats up and the subsequent increased fission-gas release from the fuel to the gap may result in fuel sheath failure. After fuel sheath failure, the barrier between the coolant and the fuel pellets is lost or impaired, gases and vapours from the fuel-to-sheath gap and other open voids in the fuel pellets can be vented. Gases and steam from the coolant can enter the broken fuel sheath and interact with the fuel pellet surfaces and the fission-product inclusion on the fuel surface (including material at the surface of the fuel matrix). The chemistry of this interaction is an important mechanism to model in order to assess fission-product releases from fuel. Starting in 1995, the computer program SOURCE 2.0 was developed by the Canadian nuclear industry to model fission-product release from fuel during such accidents. SOURCE 2.0 has employed an early thermochemical model of irradiated uranium dioxide fuel developed at the Royal Military College of Canada. To overcome the limitations of computers of that time, the implementation of the RMC model employed lookup tables to pre-calculated equilibrium conditions. In the intervening years, the RMC model has been improved, the power of computers has increased significantly, and thermodynamic subroutine libraries have become available. This thesis is the result of extensive work based on these three factors. A prototype computer program (referred to as SC11) has been developed that uses a thermodynamic subroutine library to calculate thermodynamic equilibria using Gibbs energy minimization. The Gibbs energy minimization requires the system temperature (T) and pressure (P), and the inventory of chemical elements (n) in the system. In order to calculate the inventory of chemical elements in the fuel, the list of nuclides and nuclear isomers modelled in SC11 had to be expanded from the list used by SOURCE 2.0. A
Calculation of the decay power of fission products considering neutron capture transformation
International Nuclear Information System (INIS)
The decay power of fission products has been calculated taking into consideration the neutron capture transformation of each nuclide and its beta decay. The nuclear data library contains 1114 nuclides of which 144 are stable. Neutron capture transformation is considered for 59 nuclides, 31 of which are stable. The atom number of each nuclide is calculated analytically with code DCHAIN. The effect of neutron capture transformation in the decay power of fission products was examined by varying the neutron spectrum, neutron flux, fissioning nuclide, and irradiation and cooling time. From the results obtained the following were revealed: The effect of neutron capture increases with neutron flux and irradiation time, and it becomes salient beyond 105 sec in cooling time. It is small for less than the 104 sec which is important in the design of ECCS (emergency core cooling system) of a light-water reactor. In this region the decay power changes are small, less than 0.2%, by the neutron capture for the thermal fission of 235U irradiated for one year to thermal neutron flux 3 x 1013 n/cm2/sec. The effect of neutron capture has peaks around cooling time 106 sec and 108 sec; it is negligible beyond 109 sec. The changes in decay power are 2.4%, 10.5% and 0.2% at cooling time 106 sec, 108 sec and 109 sec, respectively, in the above irradiation. Around 106 sec, the change in decay power is mainly from the contributions of 134Cs (17%), sup(148m)Pm(60%) and 148Pm(14%). Around 108 sec 134Cs(98%) alone contributes to the change in decay power. (author)
Contribution to decay heat calculation: fission product mean beta and gamma assessment
International Nuclear Information System (INIS)
Following a reactor shutdown, after the fission chain process has completely faded out, a significant quantity of energy (around seven per cent of the total power of the reactor) continues to be generated in the core. This is known as residual power or decay heat. The principal source of this energy is due to the radioactive decay of fission products and is at any time equal to the sum of the powers released by these different nuclei (P = Σ = Pi). Each of the powers Pi is the product of three terms: the concentration of the relevant nuclide, its decay constant and its mean decay energy. The evaluation of the first two term is straightforward. On the other hand the evaluation of the mean energies presents some difficulties due to a lack of data in beta and gamma spectra of some fission products. This study intends, after a critical analysis of the current method of evaluation of the mean energies, to propose a new model for this calculation. The new model tested on several well known nuclides, has been proved correct and precise. It has then been applied to approximatively sixty nuclides among the lesser known ones. The results obtained have lead to a better prediction of both beta and gamma ray components of the residual power. Consequently, this new model, which allows to take into account the lack of beta branching ratio corresponding to the highest levels of the product nucleus in the beta decay reaction, can be adopted to replace the current method, for calculation of the mean energies of fission products, especially in the case of the lesser known nuclides
International Nuclear Information System (INIS)
The thermo-mechanical analysis of fuel bundle is done using FUDA software program to calculate the fission gas release and pin pressure. The fission gas release analysis was done for the average fuel dimensions. In addition, a parametric study was also performed by varying the different parameters within their specified tolerances. The thermal conductivity calculation in the present analysis accounts for the density changes and temperature variation. The feed back of gap conductance change due to fission gas accumulation in pellet clad gap is considered in fuel temperature calculations. The present paper discusses the inputs to the FUDA, mathematical model used in calculation of fission gas release and results of gas release from the FUDA runs for the above discussed analysis. (author)
International Nuclear Information System (INIS)
The Workshop on Sub-critical Neutron Production held at the University of Maryland and the Eisenhower Institute on 11-13 October 2004 brought together members of fusion, fission and accelerator technical communities to discuss issues of spent fuel, nonproliferation, reactor safety and the use of neutrons for sub-critical operation of nuclear reactors. The Workshop strongly recommended that the fusion community work closely with other technical communities to ensure that a wider range of technical solutions is available to solve the spent fuel problem and to utilize the current actinide inventories. Participants of the Workshop recommended that a follow-on Workshop, possibly under the aegis of the IAEA, should be held in the first half of the year 2005. The Consultancy Meeting is the response to this recommendation. The objectives of the Consultancy meeting were to hold discussions on the role of fusion/fission systems in sub-critical operations of nuclear reactors. The participants agreed that development of innovative (fourth generation) fission reactors, advanced fuel cycle options, and disposition of existing spent nuclear fuel inventories in various Member Sates can significantly benefit from including sub-critical systems, which are driven by external neutron sources. Spallation neutrons produced by accelerators have been accepted in the past as the means of driving sub-critical reactors. The accelerator community deserves credit in pioneering this novel approach to reactor design. Progress in the design and operation of fusion devices now offers additional innovative means, broadening the range of sub-critical operations of fission reactors. Participants felt that fusion should participate with accelerators in providing a range of technical options in reactor design. Participants discussed concrete steps to set up a small fusion/fission system to demonstrate actinide burning in the laboratory and what advice should be given to the Agency on its role in
Activation Calculation for a Fusion Experimental Breeder FEB-E
Institute of Scientific and Technical Information of China (English)
FENGKaiming
2002-01-01
A fusion breeder might be an essential intermediate application of fusion energy at earlier term, since it has the potential to provide plenty of commercial fissile fuel. Based on fusion physics and technologies available at present and in the near future, the realistic fusion experimental breeder, FEB-E was designed.
International Nuclear Information System (INIS)
We present fission-barrier-height calculations for nuclei throughout the periodic system based on a realistic theoretical model of the multi-dimensional potential-energy surface of a fissioning nucleus. This surface guides the nuclear shape evolution from the ground state, over inner and outer saddle points, to the final configurations of separated fission fragments. We have previously shown that our macroscopic-microscopic nuclear potential-energy model yields calculated 'outer' fission-barrier heights (EB) for even-even nuclei throughout the periodic system that agree with experimental data to within about 1.0 MeV. We present final results of this work. Just recently we have enhanced our macroscopic-microscopic nuclear potential-energy model to also allow the consideration of axially asymmetric shapes. This shape degree of freedom has a substantial effect on the calculated height (EA) of the inner peak of some actinide fission barriers. We present examples of fission-barrier calculations by use of this model with its redetermined constants. Finally we discuss what the model now tells us about fission barriers at the end of the r-process nucleosynthesis path. (author)
Directory of Open Access Journals (Sweden)
N. Carjan
2015-07-01
Full Text Available The main properties of the neutrons released during the neck rupture are calculated for U236 in the frame of a dynamical scission model: the angular distribution with respect to the fission axis (on spheres of radii R=30 and 40 fm and at time T=4×10−21 s, the distribution of the average neutron energies (for durations of the neck rupture ΔT=1 and 2×10−22 s and the total neutron multiplicity (for two values of the minimum neck-radius rmin=1.6 and 1.9 fm. They are compared with measurements of prompt fission neutrons during U235(nth,f. The experimental trends are qualitatively reproduced, i.e., the focusing of the neutrons along the fission axis, the preference of emission from the light fragment, the range, slope and average value of the neutron energy-spectrum and the average total neutron multiplicity.
Energy Technology Data Exchange (ETDEWEB)
Farmer, J C; Diaz de la Rubia, T; Moses, E
2008-12-23
The National Ignition Facility (NIF) project, a laser-based Inertial Confinement Fusion (ICF) experiment designed to achieve thermonuclear fusion ignition and burn in the laboratory, is under construction at the Lawrence Livermore National Laboratory (LLNL) and will be completed in April of 2009. Experiments designed to accomplish the NIF's goal will commence in late FY2010 utilizing laser energies of 1 to 1.3 MJ. Fusion yields of the order of 10 to 20 MJ are expected soon thereafter. Laser initiated fusion-fission (LIFE) engines have now been designed to produce nuclear power from natural or depleted uranium without isotopic enrichment, and from spent nuclear fuel from light water reactors without chemical separation into weapons-attractive actinide streams. A point-source of high-energy neutrons produced by laser-generated, thermonuclear fusion within a target is used to achieve ultra-deep burn-up of the fertile or fissile fuel in a sub-critical fission blanket. Fertile fuels including depleted uranium (DU), natural uranium (NatU), spent nuclear fuel (SNF), and thorium (Th) can be used. Fissile fuels such as low-enrichment uranium (LEU), excess weapons plutonium (WG-Pu), and excess highly-enriched uranium (HEU) may be used as well. Based upon preliminary analyses, it is believed that LIFE could help meet worldwide electricity needs in a safe and sustainable manner, while drastically shrinking the nation's and world's stockpile of spent nuclear fuel and excess weapons materials. LIFE takes advantage of the significant advances in laser-based inertial confinement fusion that are taking place at the NIF at LLNL where it is expected that thermonuclear ignition will be achieved in the 2010-2011 timeframe. Starting from as little as 300 to 500 MW of fusion power, a single LIFE engine will be able to generate 2000 to 3000 MWt in steady state for periods of years to decades, depending on the nuclear fuel and engine configuration. Because the fission
International Nuclear Information System (INIS)
The National Ignition Facility (NIF) project, a laser-based Inertial Confinement Fusion (ICF) experiment designed to achieve thermonuclear fusion ignition and burn in the laboratory, is under construction at the Lawrence Livermore National Laboratory (LLNL) and will be completed in April of 2009. Experiments designed to accomplish the NIF's goal will commence in late FY2010 utilizing laser energies of 1 to 1.3 MJ. Fusion yields of the order of 10 to 20 MJ are expected soon thereafter. Laser initiated fusion-fission (LIFE) engines have now been designed to produce nuclear power from natural or depleted uranium without isotopic enrichment, and from spent nuclear fuel from light water reactors without chemical separation into weapons-attractive actinide streams. A point-source of high-energy neutrons produced by laser-generated, thermonuclear fusion within a target is used to achieve ultra-deep burn-up of the fertile or fissile fuel in a sub-critical fission blanket. Fertile fuels including depleted uranium (DU), natural uranium (NatU), spent nuclear fuel (SNF), and thorium (Th) can be used. Fissile fuels such as low-enrichment uranium (LEU), excess weapons plutonium (WG-Pu), and excess highly-enriched uranium (HEU) may be used as well. Based upon preliminary analyses, it is believed that LIFE could help meet worldwide electricity needs in a safe and sustainable manner, while drastically shrinking the nation's and world's stockpile of spent nuclear fuel and excess weapons materials. LIFE takes advantage of the significant advances in laser-based inertial confinement fusion that are taking place at the NIF at LLNL where it is expected that thermonuclear ignition will be achieved in the 2010-2011 timeframe. Starting from as little as 300 to 500 MW of fusion power, a single LIFE engine will be able to generate 2000 to 3000 MWt in steady state for periods of years to decades, depending on the nuclear fuel and engine configuration. Because the fission blanket in a fusion-fission
Energy Technology Data Exchange (ETDEWEB)
Perkasa, Y. S. [Department of Physics, Sunan Gunung Djati State Islamic University Bandung, Jl. A.H Nasution No. 105 Cibiru, Bandung (Indonesia); Waris, A., E-mail: awaris@fi.itb.ac.id; Kurniadi, R., E-mail: awaris@fi.itb.ac.id; Su' ud, Z., E-mail: awaris@fi.itb.ac.id [Nuclear Physics and Biophysics Research Division, Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa No. 10 Bandung 40132 (Indonesia)
2014-09-30
Comparative studies of actinide and sub-actinide fission cross section calculation from MCNP6 and TALYS have been conducted. In this work, fission cross section resulted from MCNP6 prediction will be compared with result from TALYS calculation. MCNP6 with its event generator CEM03.03 and LAQGSM03.03 have been validated and verified for several intermediate and heavy nuclides fission reaction data and also has a good agreement with experimental data for fission reaction that induced by photons, pions, and nucleons at energy from several ten of MeV to about 1 TeV. The calculation that induced within TALYS will be focused mainly to several hundred MeV for actinide and sub-actinide nuclides and will be compared with MCNP6 code and several experimental data from other evaluator.
International Nuclear Information System (INIS)
A high-yield, room temperature, double-shell target design using a Nd : glass laser driver at the fundamental frequency 1ω is developed for hybrid inertial fusion-fission energy generation (Moses et al 2009 Fusion Sci. Technol. 56 547). The associated 4-10x fission energy gain relaxes the gain requirements of the fusion driver, enabling the prospect of a volume-ignition target with high thermonuclear burn fraction, simplified (1ω) laser operations from a quasi-impulsive power history, room temperature fielding, minimal shock-timing requirements and reduced risk of plasma-mediated laser backscatter with a vacuum hohlraum.
Isotopic resolution of fission fragments from 238U + 12C transfer and fusion reactions
International Nuclear Information System (INIS)
Recent results from an experiment at GANIL, performed to investigate the main properties of fission-fragment yields and energy distributions in different fissioning nuclei as a function of the excitation energy, in a neutron-rich region of actinides, are presented. Transfer reactions in inverse kinematics between a 238U beam and a 12C target produced different actinides, within a range of excitation energy below 30 MeV. These fissioning nuclei are identified by detecting the target-like recoil, and their kinetic and excitation energy are determined from the reconstruction of the transfer reaction. The large-acceptance spectrometer VAMOS was used to identify the mass, atomic number and charge state of the fission fragments in flight. As a result, the characteristics of the fission-fragment isotopic distributions of a variety of neutron-rich actinides are observed for the first time over the complete range of fission fragments. (authors)
Main restrictions in the synthesis of new superheavy elements: Quasifission and/or fusion fission
Energy Technology Data Exchange (ETDEWEB)
Nasirov, Avazbek [Joint Institute for Nuclear Research, BLTP, Dubna (Russian Federation); Institute of Nuclear Physics, Tashkent (Uzbekistan); Kim, Kyungil; Kim, Youngman [Institute for Basic Science, Rare Isotope Science Project, Daejeon (Korea, Republic of); Mandaglio, Giuseppe [Dipartimento di Fisica e di Scienze della Terra dell' Universita di Messina, Messina (Italy); Istituto Nazionale di Fisica Nucleare, Rome (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Giardina, Giorgio [Dipartimento di Fisica e di Scienze della Terra dell' Universita di Messina, Messina (Italy); Istituto Nazionale di Fisica Nucleare, Rome (Italy); Muminov, Akhtam [Institute of Nuclear Physics, Tashkent (Uzbekistan)
2013-11-15
The synthesis of superheavy elements stimulates the effort to study the peculiarities of the complete fusion with massive nuclei and to improve theoretical models in order to extract knowledge about reaction mechanism in heavy-ion collisions at low energies. We compare the theoretical results of the compound nucleus (CN) formation and evaporation residue (ER) cross sections obtained for the {sup 48}Ca + {sup 248}Cm and {sup 58}Fe + {sup 232}Th reactions leading to formation of CN with A = 296 and A = 290 of the superheavy element Lv (Z = 116), respectively. The ER cross sections, which can be measured directly, are determined by the complete fusion and survival probabilities of the heated and rotating CN. Those probabilities cannot be measured unambiguously but the knowledge about them is important to study the formation mechanism of the observed products and to estimate the ER cross sections of the expected isotopes of elements. To this aim, the {sup 48}Ca + {sup 249}Cf and {sup 64}Ni + {sup 232}Th reactions are considered too. The use of the mass values of superheavy nuclei calculated in the framework of the macroscopic-microscopic model by the Warsaw group leads to smaller ER cross section for all of the reactions in comparison with the case of using the masses calculated by P. Moeller et al. (orig.)
Development of calculation code of fission products specific activity in primary coolant
International Nuclear Information System (INIS)
Based on an assumption of that there is a design basis fuel defect level from reactor startup, calculation method of fission products specific activities in primary coolant is studied. Time-dependent nuclide activities in defect fuel are calculated by ORIGEN code, and nuclide releases from the defect fuel are considered. After processed by interface codes, data are used by PCFPA code which is used to calculate nuclide activities in the coolant. PCFPA solves differential equations by unit of decay chain, and totally considers decay's contribution to nuclide activities, and considers different system design between secondary and third generation plants such as AP1000. The method could provide the maximum of specific activity during plant operation and their results are consistent with data in AP1000 DCD(Rev.16). The method could be applicable to shielding design in secondary and third generation plants such as AP1000. (authors)
Calculation of fissile nuclides and fission products inventory applied to ETRR-1 research reactor
International Nuclear Information System (INIS)
The study of the nuclear reactor fuel safety implies studying physical mechanical, thermal and chemical proportions of the fuel during normal operation and accident conditions. A model was developed to calculate the fissile nuclides and fission products inventory in an operating reactor. The model considers the production and removal of different radionuclides leaking into account the decay schemes of each. The mathematical formulas were treated without any approximations. A decay model was developed for the period after reactor shutdown. The amount of different nuclides was evaluated for a given cooling time. Egypt test and research reactor number 1, ETRR-1. Was chosen to apply the model. The amount of about 200 nuclides was calculated. A certain nuclides was chosen to be presented based on their poisoning ratios. Criticality calculations were carried out to investigate the criticality condition of the reactor at different operating times. 4 fig
Nuclear model calculation on neutron induced fission fragment mass yields of 238U
International Nuclear Information System (INIS)
The fission fragment mass yield is one of the most important characteristics of the fission process in both applications and basic nuclear physics. In nuclear energy applications, the configuration of fission products must be known because they are accumulated during the operation of a nuclear reactor. In theoretical physics, the ability to describe and predict fission yields is required for an effective nuclear fission model. Since the nuclear fission process is described by a great number of parameters, and the existing theoretical models fail to describe the fission process completely, the fission yields are amongst the most important consequences to benchmark the validity of fission models. In the present study, two different approaches to predict the neutron-induced fission fragment mass distribution of 238U has been applied. The first approach is temperature dependent Brosa model, and the other based on GEF model. The model-based predicted results are in good agreement with the experimental data
Effects of nuclear orientation on fusion and fission in the reaction using 238U target nucleus
Hirose K.; Hofmann S.; Ohtsuki T.; Nagame Y.; Nishinaka I.; Mitsuoka S.; Ikezoe H.; Nishio K.
2011-01-01
Fission fragment mass distributions in the reaction of 30Si+238U were measured around the Coulomb barrier. At the above-barrier energies, the mass distribution showed a Gaussian shape. At the subbarrier energies, triple-humped distribution was observed, which consists of symmetric fission and asymmetric fission peaked at AL/AH ≈ 90/178. The asymmetric fission should be attributed to quasifission from the results of the measured evaporation residue (ER) cross-sections for 30Si+238U. Th...
Quantum calculation of Coulomb reorientation and near-barrier fusion
Simenel, Cédric; Bender, Michael; Chomaz, P.; Duguet, Thomas; de France, G.
2006-01-01
6pages, 2 figures. Proceeding of FUSION06 International audience We investigate the role of deformation on the fusion probability around the barrier using the Time-Dependent Hartree-Fock theory with a full Skyrme force. We obtain a distribution of fusion probabilities around the nominal barrier due to the different contributions of the various orientations of the deformed nucleus at the touching point. It is also shown that the long range Coulomb reorientation reduces the fusion probabi...
Calculation of neutron importance function in fissionable assemblies using Monte Carlo method
International Nuclear Information System (INIS)
The purpose of the present work is to develop an efficient solution method to calculate neutron importance function in fissionable assemblies for all criticality conditions, using Monte Carlo Method. The neutron importance function has a well important role in perturbation theory and reactor dynamic calculations. Usually this function can be determined by calculating adjoint flux through out solving the Adjoint weighted transport equation with deterministic methods. However, in complex geometries these calculations are very difficult. In this article, considering the capabilities of MCNP code in solving problems with complex geometries and its closeness to physical concepts, a comprehensive method based on physical concept of neutron importance has been introduced for calculating neutron importance function in sub-critical, critical and supercritical conditions. For this means a computer program has been developed. The results of the method has been benchmarked with ANISN code calculations in 1 and 2 group modes for simple geometries and their correctness has been approved for all three criticality conditions. Ultimately, the efficiency of the method for complex geometries has been shown by calculation of neutron importance in MNSR research reactor
In-core thermal hydraulic and fission product calculations for severe fuel damage analyses
International Nuclear Information System (INIS)
Best-estimate calculations of realistic source terms are presented which reduce uncertainties in predicting fission product release from the UO2 fuel over the temperature range between 770 K and 3000 K. The proposed method of correlation includes such fuel morphology effects as equiaxed fuel grain growth and fuel-cladding interaction. The method correlates the product of fuel release rate and equiaxed grain size with the inverse fuel temperature to yield a bulk mass transfer correlation. It was found that less and slower releases are predicted utilizing the bulk mass transfer correlation than such conventional literature correlations as the steam oxidation model and the NUREG-0956 correlation. A Severe Fuel Damage (SFD) analysis code was developed to perform the thermal hydraulic and fission product calculations needed to analyze the Power Burst Facility SFD tests. The predictions utilizing the bulk mass transfer correlations overall followed the experimental time-release histories during the course of the heatup, power hold and cooldown phases of the transients. Good agreements were achieved for the integral releases both in timing and in magnitude. The proposed bulk mass transfer correlations can be applied to both current and advanced light water reactor fuels. 17 refs., 8 figs., 3 tabs
International Nuclear Information System (INIS)
The extension of the periodic system into various new areas is investigated. Experiments for the synthesis of superheavy elements and the predictions of magic numbers are reviewed. Different channels of nuclear decay are discussed like cluster radioactivity, cold fission and cold multifragmentation, including the recent discovery of the tripple fission of 252Cf
International Nuclear Information System (INIS)
SOURCE 2.0 is a computer code being jointly developed within the Canadian nuclear industry. It will model the necessary mechanisms required to calculate the fission product release for a variety of accident scenarios, including large break loss of coolant accidents with or without emergency coolant injection. This paper presents the origin of SOURCE 2.0, describes the code structure, the fission product mechanisms modelled, and the quality assurance procedures that are being followed during the code's life cycle. (author)
Energy Technology Data Exchange (ETDEWEB)
Ni Muyi, E-mail: nimuyi@mail.ustc.edu.cn [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui, 230026 (China); Song Yong [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui, 230026 (China); Jin Ming; Jiang Jieqiong [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Huang Qunying [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui, 230026 (China)
2012-08-15
Highlights: Black-Right-Pointing-Pointer A concept of the tritium system was designed for the FDS-MFX. Black-Right-Pointing-Pointer The system parameters were presented and discussed in detail. Black-Right-Pointing-Pointer A theoretical analysis of tritium recovery system has been made on the operation condition. Black-Right-Pointing-Pointer Three step TEP system was design and its permeating capacity was estimated. Black-Right-Pointing-Pointer The model of three-column ISS and the SDS was also carried out. - Abstract: As early application of fusion technology, the fusion-fission hybrid systems/reactors could be used to transmute long-lived radioactive waste and produce fissile nuclear fuel. A fusion-fission hybrid reactor named FDS-MFX was designated for checking and validating the DEMO reactor blanket relevant technologies. The reactor design is based on easy-achieved plasma parameters extrapolated from the successful operation of tokamaks and the subcritical blanket is designed based on the well-developed technologies of fission reactors. In this contribution, a concept of the tritium system was designed for the FDS-MFX: the tritium was extracted from LiPb by the helium purge gas which contains a small amount of hydrogen gas, then the impurity gas was removed by cold trap, finally tritium was separated from hydrogen isotope by the cryogenic distillation and supply to reactor core. On the basis of data obtained by present design and experimental research, the system parameters were presented and discussed in detail. The results preliminarily demonstrated the engineering feasibility of the design.
Delayed neutron spectra and their uncertainties in fission product summation calculations
Energy Technology Data Exchange (ETDEWEB)
Miyazono, T.; Sagisaka, M.; Ohta, H.; Oyamatsu, K.; Tamaki, M. [Nagoya Univ. (Japan)
1997-03-01
Uncertainties in delayed neutron summation calculations are evaluated with ENDF/B-VI for 50 fissioning systems. As the first step, uncertainty calculations are performed for the aggregate delayed neutron activity with the same approximate method as proposed previously for the decay heat uncertainty analyses. Typical uncertainty values are about 6-14% for {sup 238}U(F) and about 13-23% for {sup 243}Am(F) at cooling times 0.1-100 (s). These values are typically 2-3 times larger than those in decay heat at the same cooling times. For aggregate delayed neutron spectra, the uncertainties would be larger than those for the delayed neutron activity because much more information about the nuclear structure is still necessary. (author)
International Nuclear Information System (INIS)
A conceptual design of fusion-fission hybrid reactor for energy production, named FDS-EM (Energy Multiplier), was proposed. It was preliminary designed to generate about an electricity power of about 1.0 GW with self-sustaining tritium cycle. This contribution performed the thermal-hydraulics design and analyses for FDS-EM water-cooled blanket. The typical thermal-hydraulics parameters were designed by using mature technologies of PWR, and temperature and stress analyses were carried out, according to typical parameters of the blanket. The results preliminarily demonstrated the engineering feasibility of the design. (authors)
Energy Technology Data Exchange (ETDEWEB)
Greenwood, L.R.; Garner, A.F.
1996-04-01
Whilte the influence of transmutant helium on radiation-induced microstructural evolution has often been studied, there is a tendency to overlook the influence of concurrently-generated hydrogen. There have been some recent speculation and studies, however, that suggest that the influence of hydrogen may be enhanced in the presence of large amounts of helium, especially at lower irradiation temperatures typical of projected ITER operation. The impact of the (n,p) reaction on both hydrogen generation rates and displacement rates are evaluated in this paper for a variety of neutron spectra employed in fission-fusion correlation.
Energy Technology Data Exchange (ETDEWEB)
Smith, P.D.
1978-02-01
A special purpose computer program, TRAFIC, is presented for calculating the release of metallic fission products from an HTGR core. The program is based upon Fick's law of diffusion for radioactive species. One-dimensional transient diffusion calculations are performed for the coated fuel particles and for the structural graphite web. A quasi steady-state calculation is performed for the fuel rod matrix material. The model accounts for nonlinear adsorption behavior in the fuel rod gap and on the coolant hole boundary. The TRAFIC program is designed to operate in a core survey mode; that is, it performs many repetitive calculations for a large number of spatial locations in the core. This is necessary in order to obtain an accurate volume integrated release. For this reason the program has been designed with calculational efficiency as one of its main objectives. A highly efficient numerical method is used in the solution. The method makes use of the Duhamel superposition principle to eliminate interior spatial solutions from consideration. Linear response functions relating the concentrations and mass fluxes on the boundaries of a homogeneous region are derived. Multiple regions are numerically coupled through interface conditions. Algebraic elimination is used to reduce the equations as far as possible. The problem reduces to two nonlinear equations in two unknowns, which are solved using a Newton Raphson technique.
Density functional theory calculations of defect and fission gas properties in U-Si fuels
International Nuclear Information System (INIS)
Accident tolerant fuels (ATF) are being developed in response to the Fukushima Daiichi accident in Japan. One of the options being pursued is U-Si fuels, such as the U3Si2 and U3Si5 compounds, which benefit from high thermal conductivity (metallic) compared to the UO2 fuel (insulator or semi-conductor) used in current Light Water Reactors (LWRs). The U-Si fuels also have higher fissile density. In order to perform meaningful engineering scale nuclear fuel performance simulations, the material properties of the fuel, including the response to irradiation environments, must be known. Unfortunately, the data available for U-Si fuels are rather limited, in particular for the temperature range where LWRs would operate. The ATF HIP is using multi-scale modeling and simulations to address this knowledge gap. The present study investigates point defect and fission gas properties in U3Si2, which is one of the main fuel candidates, using density functional theory (DFT) calculations. Based on a few assumption regarding entropy contributions, defect and fission diffusivities are predicted. Even though uranium silicides have been shown to amorphize easily at low temperature, we assume that U3Si2 remains crystalline under the conditions expected in Light Water Reactors (LWRs). The temperature and dose where amorphization occurs has not yet been well established.
Directory of Open Access Journals (Sweden)
Porta A.
2016-01-01
Full Text Available Beta decay of fission products is at the origin of decay heat and antineutrino emission in nuclear reactors. Decay heat represents about 7% of the reactor power during operation and strongly impacts reactor safety. Reactor antineutrino detection is used in several fundamental neutrino physics experiments and it can also be used for reactor monitoring and non-proliferation purposes. 92,93Rb are two fission products of importance in reactor antineutrino spectra and decay heat, but their β-decay properties are not well known. New measurements of 92,93Rb β-decay properties have been performed at the IGISOL facility (Jyväskylä, Finland using Total Absorption Spectroscopy (TAS. TAS is complementary to techniques based on Germanium detectors. It implies the use of a calorimeter to measure the total gamma intensity de-exciting each level in the daughter nucleus providing a direct measurement of the beta feeding. In these proceedings we present preliminary results for 93Rb, our measured beta feedings for 92Rb and we show the impact of these results on reactor antineutrino spectra and decay heat calculations.
Porta, A.; Zakari-Issoufou, A.-A.; Fallot, M.; Algora, A.; Tain, J. L.; Valencia, E.; Rice, S.; Bui, V. M.; Cormon, S.; Estienne, M.; Agramunt, J.; Äystö, J.; Bowry, M.; Briz, J. A.; Caballero-Folch, R.; Cano-Ott, D.; Cucouanes, A.; Elomaa, V.-V.; Eronen, T.; Estévez, E.; Farrelly, G. F.; Garcia, A. R.; Gelletly, W.; Gomez-Hornillos, M. B.; Gorlychev, V.; Hakala, J.; Jokinen, A.; Jordan, M. D.; Kankainen, A.; Karvonen, P.; Kolhinen, V. S.; Kondev, F. G.; Martinez, T.; Mendoza, E.; Molina, F.; Moore, I.; Perez-Cerdán, A. B.; Podolyák, Zs.; Penttilä, H.; Regan, P. H.; Reponen, M.; Rissanen, J.; Rubio, B.; Shiba, T.; Sonzogni, A. A.; Weber, C.
2016-03-01
Beta decay of fission products is at the origin of decay heat and antineutrino emission in nuclear reactors. Decay heat represents about 7% of the reactor power during operation and strongly impacts reactor safety. Reactor antineutrino detection is used in several fundamental neutrino physics experiments and it can also be used for reactor monitoring and non-proliferation purposes. 92,93Rb are two fission products of importance in reactor antineutrino spectra and decay heat, but their β-decay properties are not well known. New measurements of 92,93Rb β-decay properties have been performed at the IGISOL facility (Jyväskylä, Finland) using Total Absorption Spectroscopy (TAS). TAS is complementary to techniques based on Germanium detectors. It implies the use of a calorimeter to measure the total gamma intensity de-exciting each level in the daughter nucleus providing a direct measurement of the beta feeding. In these proceedings we present preliminary results for 93Rb, our measured beta feedings for 92Rb and we show the impact of these results on reactor antineutrino spectra and decay heat calculations.
Density functional theory calculations of defect and fission gas properties in U-Si fuels
Energy Technology Data Exchange (ETDEWEB)
Andersson, Anders David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-02-03
Accident tolerant fuels (ATF) are being developed in response to the Fukushima Daiichi accident in Japan. One of the options being pursued is U-Si fuels, such as the U_{3}Si_{2} and U_{3}Si_{5} compounds, which benefit from high thermal conductivity (metallic) compared to the UO_{2} fuel (insulator or semi-conductor) used in current Light Water Reactors (LWRs). The U-Si fuels also have higher fissile density. In order to perform meaningful engineering scale nuclear fuel performance simulations, the material properties of the fuel, including the response to irradiation environments, must be known. Unfortunately, the data available for U-Si fuels are rather limited, in particular for the temperature range where LWRs would operate. The ATF HIP is using multi-scale modeling and simulations to address this knowledge gap. The present study investigates point defect and fission gas properties in U_{3}Si_{2}, which is one of the main fuel candidates, using density functional theory (DFT) calculations. Based on a few assumption regarding entropy contributions, defect and fission diffusivities are predicted. Even though uranium silicides have been shown to amorphize easily at low temperature, we assume that U_{3}Si_{2} remains crystalline under the conditions expected in Light Water Reactors (LWRs). The temperature and dose where amorphization occurs has not yet been well established.
Energy Technology Data Exchange (ETDEWEB)
Jo, Yu Gwon; Cho, Nam Zin [KAIST, Daejeon (Korea, Republic of)
2014-10-15
The OLG iteration scheme uses overlapping regions for each local problem solved by continuous-energy MC calculation to reduce errors in inaccurate boundary conditions (BCs) that are caused by discretization in space, energy, and angle. However, the overlapping region increases computational burdens and the discretized BCs for continuous-energy MC calculation result in an inaccurate global p-CMFD solution. On the other hand, there also have been several studies on the direct domain decomposed MC calculation where each processor simulates particles within its own domain and exchanges the particles crossing the domain boundary between processors with certain frequency. The efficiency of this method depends on the message checking frequency and the buffer size. Furthermore, it should overcome the load-imbalance problem for better parallel efficiency. Recently, fission and surface source (FSS) iteration method based on banking both fission and surface sources for the next iteration (i.e., cycle) was proposed to give exact BCs for non overlapping local problems in domain decomposition and tested in one-dimensional continuous-energy reactor problems. In this paper, the FSS iteration method is combined with a source splitting scheme to reduce the load imbalance problem and achieve global variance reduction. The performances are tested on a two dimensional continuous-energy reactor problem with domain-based parallelism and compared with the FSS iteration without source splitting. Numerical results show the improvements of the FSS iteration with source splitting. This paper describes the FSS iteration scheme in the domain decomposition method and proposes the FSS iteration combined with the source splitting based on the number of sampled sources, reducing the load-imbalance problem in domain-based parallelism and achieving global variance reduction.
Berge, Léonie
2015-01-01
The prompt fission neutron spectrum (PFNS) is very important for various nuclear physics applications. Yet, except for the 252Cf spontaneous fission spectrum which is an international standard and is used for metrology purposes, the PFNS is still poorly known for most of the fissionning nuclides. In particular, few measurements exist for the fast fission spectrum (induced by a neutron whose energy exceeds about 100 keV), and the international evaluations show strong discrepancies. There are a...
Benchmarking Nuclear Fission Theory
G. F. Bertsch(INT, Seattle, USA); Loveland, W.; Nazarewicz, W.; Talou, P.
2015-01-01
We suggest a small set of fission observables to be used as test cases for validation of theoretical calculations. The purpose is to provide common data to facilitate the comparison of different fission theories and models. The proposed observables are chosen from fission barriers, spontaneous fission lifetimes, fission yield characteristics, and fission isomer excitation energies.
Tol, Marc J; Ottenhoff, Roelof; van Eijk, Marco; Zelcer, Noam; Aten, Jan; Houten, Sander M; Geerts, Dirk; van Roomen, Cindy; Bierlaagh, Marlou C; Scheij, Saskia; Hoeksema, Marten A; Aerts, Johannes M; Bogan, Jonathan S; Dorn, Gerald W; Argmann, Carmen A; Verhoeven, Arthur J
2016-09-01
Aberrant mitochondrial fission plays a pivotal role in the pathogenesis of skeletal muscle insulin resistance. However, fusion-fission dynamics are physiologically regulated by inherent tissue-specific and nutrient-sensitive processes that may have distinct or even opposing effects with respect to insulin sensitivity. Based on a combination of mouse population genetics and functional in vitro assays, we describe here a regulatory circuit in which peroxisome proliferator-activated receptor γ (PPARγ), the adipocyte master regulator and receptor for the thiazolidinedione class of antidiabetic drugs, controls mitochondrial network fragmentation through transcriptional induction of Bnip3. Short hairpin RNA-mediated knockdown of Bnip3 in cultured adipocytes shifts the balance toward mitochondrial elongation, leading to compromised respiratory capacity, heightened fatty acid β-oxidation-associated mitochondrial reactive oxygen species generation, insulin resistance, and reduced triacylglycerol storage. Notably, the selective fission/Drp1 inhibitor Mdivi-1 mimics the effects of Bnip3 knockdown on adipose mitochondrial bioenergetics and glucose disposal. We further show that Bnip3 is reciprocally regulated in white and brown fat depots of diet-induced obesity and leptin-deficient ob/ob mouse models. Finally, Bnip3(-/-) mice trade reduced adiposity for increased liver steatosis and develop aggravated systemic insulin resistance in response to high-fat feeding. Together, our data outline Bnip3 as a key effector of PPARγ-mediated adipose mitochondrial network fragmentation, improving insulin sensitivity and limiting oxidative stress. PMID:27325287
Winterberg, Friedwardt
2009-01-01
The recently proposed Super Marx generator pure deuterium micro-detonation ignition concept is compared to the Lawrence Livermore National Ignition Facility (NIF) Laser DT fusion-fission hybrid concept (LiFE) [1]. In a Super Marx generator a large number of ordinary Marx generators charge up a much larger second stage ultra-high voltage Marx generator, from which for the ignition of a pure deuterium micro-explosion an intense GeV ion beam can be extracted. A typical example of the LiFE concept is a fusion gain of 30, and a fission gain of 10, making up for a total gain of 300, with about 10 times more energy released into fission as compared to fusion. This means a substantial release of fission products, as in fusion-less pure fission reactors. In the Super Marx approach for the ignition of a pure deuterium micro-detonation a gain of the same magnitude can in theory be reached [2]. If feasible, the Super Marx generator deuterium ignition approach would make lasers obsolete as a means for the ignition of ther...
International Nuclear Information System (INIS)
Full text: The implementation in the reaction code system EMPIRE-2.19 of an advanced formalism for fission cross-section calculation has been completed. The formalism is based on the optical model for fission and can be applied for nuclei exhibiting double- or triple-humped barrier starting from sub-barrier excitation energies. The optical model for fission, initially developed to describe the resonant structure of the fission cross section at sub-barrier excitation energies due to the vibrational states in the second well of a double-humped fission barrier, was extended to light actinides by including the relations for the transmission coefficients through a complex triple-humped fission barrier. The real part of the fission barrier is parameterised as a function of the nucleus deformation by five smoothly joined parabolas. The imaginary potential is introduced only in the deformation range corresponding to the second well because the tertiary well is supposed to be shallow enough to neglect the damping of class III vibrational states. The transition states are assumed to be rotational states built on vibrational or non-collective band-heads. As the excitation energy increases, the shell effect, which causes the splitting of the outer barrier, diminishes and the outer humps lump into a single one. Therefore, in the present formalism, triple-humped barriers are associated only to the discrete transition states; the contribution of continuum to the fission coefficients is calculated considering a double-humped barrier. The parameters of the second single barrier equivalent with the outer humps are being determined from the condition of equal transmission coefficients. The saddle-point transition states in continuum are described by level densities (BCS below the critical energy and a modified version of Fermi Gas above) accounting for collective enhancements specific to the nuclear shape asymmetry at each saddle point . The neutron cross sections of 232Th in the
Calculation of 239Pu fission observables in an event-by-event simulation
Energy Technology Data Exchange (ETDEWEB)
Vogt, R; Randrup, J; Pruet, J; Younes, W
2010-03-31
The increased interest in more exclusive fission observables has demanded more detailed models. We describe a new computational model, FREYA, that aims to meet this need by producing large samples of complete fission events from which any observable of interest can then be extracted consistently, including any interesting correlations. The various model assumptions are described and the potential utility of the model is illustrated. As a concrete example, we use formal statistical methods, experimental data on neutron production in neutron-induced fission of {sup 239}Pu, along with FREYA, to develop quantitative insights into the relation between reaction observables and detailed microscopic aspects of fission. Current measurements of the mean number of prompt neutrons emitted in fission taken together with less accurate current measurements for the prompt post-fission neutron energy spectrum, up to the threshold for multi-chance fission, place remarkably fine constraints on microscopic theories.
International Nuclear Information System (INIS)
We present a model which allows for the calculation of fragment excitation energy, fragment kinetic energies and neutron evaporation in nuclear fission. The model is based on the assumption that, at the end of the fission process, fragments are excited to a temperature which is proportional to the reaction Q-value. Starting from this assumption the distribution functions of fragment excitation can be formulated and the distribution functions for the kinetic energies can be derived by a Monte Carlo method. From the distribution functions for the excitation energy neutron evaporation characteristics are calculated. (author)
a Study of Fusion-Fission in the ARGON-36 + Carbon -12 System.
Farrar, Kelly Allen, Jr.
The ^{36}Ar + ^{12}C reaction at E_{lab} = 187.7 MeV has been used to populate the ^{48}Cr system at an excitation energy of 59.6 MeV. Cross sections to the A = 6, 7 and A = 9-24 decay channels have been measured and found to be consistent with fission from a fully-equilibrated compound nucleus. High-resolution mutual-excitation-energy spectra were obtained through a particle-particle coincidence measurement for the {^{14 }Mg} + {^{14}Mg} and {^{20}Ne} + {^{28}Si} exit channels. The peaks observed in these spectra at high energies were found to correspond directly to peaks seen in similar spectra obtained from an earlier measurement using the ^{24}Mg + ^{24}Mg reaction to reach the same ^{48}Cr system at an excitation energy of 59.4 MeV. The mutual excitation spectrum for the ^{24}Mg + ^{24}Mg exit channel was compared with a spectrum obtained from a calculation based on the transition-state model for light nuclei. The experimental and observed spectra were in good agreement suggesting that the observed structure can be explained in terms of a simple statistical decay picture. A particle-particle -gamma measurement was also made and the results were used to study the specific mutual excitations involved in the excitation energy peaks. It was found that the peaks are not dominated by single, mutual excitations. The results overall tend to confirm the conclusion that the source of the structure seen in the mutual-excitation spectrum at high energy is the result of a statistical population of energy levels as determined by the spin-weighting of the available phase space.
Testing actinide fission yield treatment in CINDER90 for use in MCNP6 burnup calculations
International Nuclear Information System (INIS)
Most of the development of the MCNPX/6 burnup capability focused on features that were applied to the Boltzman transport or used to prepare coefficients for use in CINDER90, with little change to CINDER90 or the CINDER90 data. Though a scheme exists for best solving the coupled Boltzman and Bateman equations, the most significant approximation is that the employed nuclear data are correct and complete. Thus, the CINDER90 library file contains 60 different actinide fission yields encompassing 36 fissionable actinides (thermal, fast, high energy and spontaneous fission). Fission reaction data exists for more than 60 actinides and as a result, fission yield data must be approximated for actinides that do not possess fission yield information. Several types of approximations are used for estimating fission yields for actinides which do not possess explicit fission yield data. The objective of this study is to test whether or not certain approximations of fission yield selection have any impact on predictability of major actinides and fission products. Further we assess which other fission products, available in MCNP6 Tier 3, result in the largest difference in production. Because the CINDER90 library file is in ASCII format and therefore easily amendable, we assess reasons for choosing, as well as compare actinide and major fission product prediction for the H. B. Robinson benchmark for, three separate fission yield selection methods: (1) the current CINDER90 library file method (Base); (2) the element method (Element); and (3) the isobar method (Isobar). Results show that the three methods tested result in similar prediction of major actinides, Tc-99 and Cs-137; however, certain fission products resulted in significantly different production depending on the method of choice
Energy Technology Data Exchange (ETDEWEB)
Gerasimenko, B.F. [V.G. Khlopin Radium Inst., Saint Peterburg (Russian Federation)
1997-03-01
The calculations of integral spectra of prompt neutrons of spontaneous fission of {sup 244}Cm and {sup 246}Cm were carried out. The calculations were done by the Statistical Computer Code Complex SCOFIN applying the Hauser-Feschbach method as applied to the description of the de-excitation of excited fission fragments by means of neutron emission. The emission of dipole gamma-quanta from these fragments was considered as a competing process. The average excitation energy of a fragment was calculated by two-spheroidal model of tangent fragments. The density of levels in an excited fragment was calculated by the Fermi-gas model. The quite satisfactory agreement was reached between theoretical and experimental results obtained in frames of Project measurements. The calculated values of average multiplicities of neutron number were 2,746 for {sup 244}Cm and 2,927 for {sup 246}Cm that was in a good accordance with published experimental figures. (author)
Solid-state laser driver for hybrid fission-fusion reactor
International Nuclear Information System (INIS)
The main objective for the laser confinement fusion project is to reach high fusion energy gain. The method developed in this paper on high power neodymium glass laser involves the pulse compression, based on the propagation of a long pulse through an amplifying system. (TEC). 10 refs., 8 figs., 2 tabs
Statistical model calculations with a double-humped fission barrier GIVAB computer code
International Nuclear Information System (INIS)
Neutron and gamma emission probabilities and fission probabilities are computed, taking into account the special feature of the actinide fission barriers with two maxima. Spectra and cross sections are directly deduced from these probabilities. Populations of both wells are followed step by step. For each initial E and J, decay rates are computed and normalized in order to obtain the de-excitation probabilities imposed by the two-humped fission barrier
Curley, Martin G.; Formica, Piero; Nicolo, Vincenzo
2011-01-01
Incubators are embedded in the culture of the economics of (value-added) services. To date, at least in Europe, they have operated in a manner analogous to the generation of nuclear power; that is, attempting to produce "entrepreneurial energy" through a process of fission that creates a division between the aspiring entrepreneurs' demands for,…
Nuclear viscosity determined from prescission neutron multiplicities in fusion-fission reactions
International Nuclear Information System (INIS)
The fast fission reaction mechanism has been studied using nuclear dynamics and evaporation models. It has been found that for the majority of the analysed reactions a deduced value of the friction coefficient strongly depend on the upper limit of an angular momentum which is a function of neutron multiplicity in the investigated process
Decay heat measurement on fusion reactor materials and validation of calculation code system
Energy Technology Data Exchange (ETDEWEB)
Maekawa, Fujio; Ikeda, Yujiro; Wada, Masayuki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
1998-03-01
Decay heat rates for 32 fusion reactor relevant materials irradiated with 14-MeV neutrons were measured for the cooling time period between 1 minute and 400 days. With using the experimental data base, validity of decay heat calculation systems for fusion reactors were investigated. (author)
International Nuclear Information System (INIS)
The purpose of this study made by General Technology Systems (Netherlands) is to provide information about nuclear fission and fusion as methods for power generation, with which, in the framework of a study into the possibilities of durable energy sources, choices may be made from the various possibilities for future energy supply. The physical processes upon which the power generation relies are treated briefly. The technologies employed are discussed together with their changes and improvements, now and in the future, and the economic factors by which they are accompanied. How much of this energy will be used in the Netherlands, is discussed. In order to know the opinion of others about these subjects the dealers of the current nuclear power stations were asked to give their opinions which are collected in a supplement. 166 refs.; 18 figs.; 19 tabs
Uranium resources and their implications for fission breeder and fusion hybrid development
International Nuclear Information System (INIS)
Present estimates of uranium resources and reserves in the US and the non-Communist world are reviewed. The resulting implications are considered for two proposed breeder technologies: the liquid metal fast breeder reactor (LMFBR) and the fusion hybrid reactor. Using both simple arguments and detailed scenarios from the published literature, conditions are explored under which the LMFBR and fusion hybrid could respectively have the most impact, considering both fuel-supply and economic factors. The conclusions emphasize strong potential advantages of the fusion hybrid, due to its inherently large breeding rate. A discussion is presented of proposed US development strategies for the fusion hybrid, which at present is far behind the LMFBR in its practical application and maturity
Calculation of the nuclear fission data based on the framework of the QMD + SDM
International Nuclear Information System (INIS)
The quantum molecular dynamics (QMD), statistical decay model (SDM) and the statistical fission theory were used to analyze the mass distribution of the fission products, the prompt fission neutron spectrum (x(E)) and the prompt fission neutron multiplicities (ν-barpf(E)) caused by the intermediate energy nucleon-induced fission. The semi-empirical formula of energy level density parameter used in the statistical process was also studied. Very few adjustable parameters were included in the present method. By some physical analysis, it can be thought that the present results are reasonable. The x(E) and ν-barpf(E) can be obtained in the intermediate energy region by the present method
International Nuclear Information System (INIS)
During the work on which this Thesis is based, the significant role of the Fusion-Fission Asymmetric mechanism in light heavy ion collisions (ANC ≤ 60) has been emphasized. The Spin Dis-alignment in the oblate-oblate system has supplied evidence for the first time for the Butterfly mode in a resonant-like reaction. These two aspects, one macroscopic and the other more closely related to microscopic effects are certainly different from a conceptual point of view but are quite complementary for a global understanding of dinuclear systems. In the first part, inclusive and exclusive measurements of the 35Cl + 12C and 35Cl + 24Mg reaction have been performed at 8 MeV/nucleon in the Saclay experiment. These measurements have permitted us to verify the origin of products which have given rise of the asymmetric fusion-fission mechanism and which have demonstrated that the three-body process in this energy range is very weak. In the second part the 28Si + 28Si reaction has been performed at the resonance energy Elab> = 111.6 MeV at Strasbourg with the Eurogam phase II multi-detector array and VIVITRON accelerator. An angular momentum Jπ 38+ for inelastic and mutual channels of the 28Si + 28Si exit channel has been measured and has supplied evidence for a spin dis-alignment which has been interpreted in the framework of a molecular model by Butterfly motion. The spectroscopic study of 32S nucleus, has revealed the occurrence of a new γ-ray transition 0+(8507.8 keV) → 21+(2230.2 keV). (author)
Fission and Fusion of Solitons for the (1+1)-Dimensional Kupershmidt Equation
Institute of Scientific and Technical Information of China (English)
YING Jin-Ping
2001-01-01
By means of the heat conduction equation and the standard truncated Painlevé expansion, the (1+1) dimensional Kupershmidt equation is solved. Some significant exact multi-soliton solutions are given. Especially; for the interaction of the multi-solitons of the Kupershmidt equation, we find that a single (resonant) kink or bell soliton may be fissioned to several kink or bell solitons. Inversely, several kink or bell solitons may also be fused to one kink or bell soliton.
Dobrowolski, Artur
2006-01-01
Dans ce travail de thèse des ingrédients essentiels pour la description théorique de la dynamique des réactions de fusion et fission nucléaires sont étudiés, tel que le potentiel d'interaction entre noyaux cible et projectile pour le processus de fusion et l'énergie de déformation dans un espace multidimensionnel pour la fission. Nous avons évalué en particulier l'importance de la différence des distributions de densités protons et neutrons. Pour le processus de fusion, le potentiel d'interac...
Díaz-Torres, A
2006-01-01
A realistic microscopically-based quantum approach to the competition between fusion and quasi-fission in a heavy fusing system is applied to several reactions leading to $^{256}$No. Fusion and quasi-fission are described in terms of a diffusion process of nuclear shapes through a dynamical collective potential energy landscape which is initially diabatic and gradually becomes adiabatic. The microscopic ingredients of the theory are obtained with a realistic two-center shell model based on Woods-Saxon potentials. The results indicate that (i) the diabatic effects play a very important role in the onset of fusion hindrance for heavy systems, and (ii) very asymmetric reactions induced by closed shell nuclei seem to be the best suited to synthesize the heaviest compound nuclei.
International Nuclear Information System (INIS)
Two critical quantities in muon-catalyzed d-t fusion are the d-t fusion rate left-angle ψ|δ(3)(rdt)|ψ right-angle and the α-μ sticking fraction |left-angle var-phi(r)eiq·r|δ(3)(r dt)|ψ(rt,r)right-angle |2/left-angle ψ|δ(3)(rdt)|ψ right-angle, where ψ is a (dtμ)+ wave function and var-phi is a hydrogenic α-μ wave function. It is explained why conventional approaches to calculate these quantities directly are slowly convergent. It is suggested that the use of a basis that explicitly includes terms that appear in the Fock expansion will lead to more rapid convergence. Furthermore, an identity relating left-angle ψ|δ(3)(r)|ψ right-angle to expectation values of more diffuse operators, which was first derived by Hiller, Sucher, and Feinberg [Phys. Rev. A 18, 2399 (1978)] and then extended by Drake [Nucl. Instrum. Methods Phys. Res. B 31, 7 (1988)] in the context of atomic calculations, is generalized to the calculation of fusion rates and sticking fractions. It is anticipated that these relations will facilitate the accurate calculation of fusion rates and of sticking fractions
Energy Technology Data Exchange (ETDEWEB)
None
2009-09-30
Largely in anticipation of a possible nuclear renaissance, there has been an enthusiastic renewal of interest in the fusion-fission hybrid concept, driven primarily by some members of the fusion community. A fusion-fission hybrid consists of a neutron-producing fusion core surrounded by a fission blanket. Hybrids are of interest because of their potential to address the main long-term sustainability issues related to nuclear power: fuel supply, energy production, and waste management. As a result of this renewed interest, the U.S. Department of Energy (DOE), with the participation of the Office of Fusion Energy Sciences (OFES), Office of Nuclear Energy (NE), and National Nuclear Security Administration (NNSA), organized a three-day workshop in Gaithersburg, Maryland, from September 30 through October 2, 2009. Participants identified several goals. At the highest level, it was recognized that DOE does not currently support any R&D in the area of fusion-fission hybrids. The question to be addressed was whether or not hybrids offer sufficient promise to motivate DOE to initiate an R&D program in this area. At the next level, the workshop participants were asked to define the research needs and resources required to move the fusion-fission concept forward. The answer to the high-level question was given in two ways. On the one hand, when viewed as a standalone concept, the fusion-fission hybrid does indeed offer the promise of being able to address the sustainability issues associated with conventional nuclear power. On the other hand, when participants were asked whether these hybrid solutions are potentially more attractive than contemplated pure fission solutions (that is, fast burners and fast breeders), there was general consensus that this question could not be quantitatively answered based on the known technical information. Pure fission solutions are based largely on existing both fusion and nuclear technology, thereby prohibiting a fair side-by-side comparison
Mass distribution in 19F induced fission of 232Th
International Nuclear Information System (INIS)
Formation cross sections of several fission products have been determined using the recoil catcher technique followed by γ-ray spectrometry in 19F induced fission of 232Th at Elab=95 and 112 MeV. The data show significant admixture of fission from compound nuclei formed by complete fusion as well as targetlike nuclei formed by transfer reactions. Mass distributions for both the fissioning systems have been obtained using the systematics of charge distribution in low and medium energy fission. Mass distribution for complete fusion fission is broad Gaussian whereas it is asymmetric for transfer induced fission. At 95 MeV the transfer fission constitutes about 28% of total fission cross section while at 112 MeV it is about 14%, showing that the transfer fission fraction decreases with increasing projectile energy across the barrier. The evaporation residue cross sections of the targetlike nucleus formed in the 232Th (19F, 18O) 233Pa reaction were also measured. The evaporation residue cross sections and the calculated decay probabilities of the targetlike nucleus 233Pa by PACE2 have been used to estimate the fraction of proton and α transfer fission in the total transfer fission cross section. copyright 1996 The American Physical Society
Feng, Song; Liu, Rong; Lu, Xinxin; Yang, Yiwei; Xu, Kun; Wang, Mei; Zhu, Tonghua; Jiang, Li; Qin, Jianguo; Jiang, Jieqiong; Han, Zijie; Lai, Caifeng; Wen, Zhongwei
2016-03-01
The 239Pu production rate is important data in neutronics design for a natural uranium blanket of a fusion-fission hybrid reactor, and the accuracy and reliability should be validated by integral experiments. The distribution of 239Pu production rates in a subcritical natural uranium blanket mock-up was obtained for the first time with a D-T neutron generator by using an activation technique. Natural uranium foils were placed in different spatial locations of the mock-up, the counts of 277.6 keV γ-rays emitted from 239Np generated by 238U capture reaction were measured by an HPGe γ spectrometer, and the self-absorption of natural uranium foils was corrected. The experiment was analyzed using the Super Monte Carlo neutron transport code SuperMC2.0 with recent nuclear data of 238U from the ENDF/B-VII.0, ENDF/B-VII.1, JENDL-4.0u2, JEFF-3.2 and CENDL-3.1 libraries. Calculation results with the JEFF-3.2 library agree with the experimental ones best, and they agree within the experimental uncertainty in general with the average ratios of calculation results to experimental results (C/E) in the range of 0.93 to 1.01.
A comparison of the radiological impact of energy production by fission and fusion reactions
International Nuclear Information System (INIS)
The impacts of respectively a light water reactor and a planned fusion reactor, for which tritium-deuterium fusion reactions will act as energy source have been compared. The comparison is made on the basis of a generated capacity of 1 GWe.year, using the following criteria: fuel inventories, radioactive releases, collective effective dose equivalent commitments to the public and the volume of wastes. The accidental risk is not introduced. Fusion reactor parameters are still subject to uncertainties, which prevent accurate quantification of radionuclide releases (tritium apart) from the nuclear plant. Only orders of magnitude extrapolated from values for the NET tokamak are given. Despite these uncertainties, it would seem more interesting, from the dosimetric point of view, to use fusion reactors to produce electricity, although problems of radioactive releases, handling and long-term storage of radioactive waste would remain. Fusion reactors also generate generate high-level wastes with long-term exposure rates that are lower than those of light water reactors
Fission Barriers of Compound Superheavy Nuclei
Pei, J C; Nazarewicz, W.; Sheikh, J. A.; Kerman, A. K.
2009-01-01
The dependence of fission barriers on the excitation energy of the compound nucleus impacts the survival probability of superheavy nuclei synthesized in heavy-ion fusion reactions. In this work, we investigate the isentropic fission barriers by means of the self-consistent nuclear density functional theory. The relationship between isothermal and isentropic descriptions is demonstrated. Calculations have been carried out for $^{264}$Fm, $^{272}$Ds, $^{278}$112, $^{292}$114, and $^{312}$124. F...
Conservation of Isospin in Neutron-rich Fission Fragments
International Nuclear Information System (INIS)
On the occasion of the 75th anniversary of the fission phenomenon, we present a surprisingly simple result which highlights the important role of isospin and its conservation in neutron rich fission fragments. We have analysed the fission fragment mass distribution from two recent heavyion reactions 238U(18O,f) and 208Pb(18O,f) as well as a thermal neutron fission reaction 245Cm(nth,f). We find that the conservation of the total isospin explains the overall trend in the observed relative yields of fragment masses in each fission pair partition. The isospin values involved are very large making the effect dramatic. The findings open the way for more precise calculations of fission fragment distributions in heavy nuclei and may have far reaching consequences for the drip line nuclei, HI fusion reactions, and calculation of decay heat in the fission phenomenon
Conservation of Isospin in Neutron-rich Fission Fragments
Jain, A. K.; Choudhury, D.; Maheshwari, B.
2014-06-01
On the occasion of the 75th anniversary of the fission phenomenon, we present a surprisingly simple result which highlights the important role of isospin and its conservation in neutron rich fission fragments. We have analysed the fission fragment mass distribution from two recent heavyion reactions 238U(18O,f) and 208Pb(18O,f) as well as a thermal neutron fission reaction 245Cm(nth,f). We find that the conservation of the total isospin explains the overall trend in the observed relative yields of fragment masses in each fission pair partition. The isospin values involved are very large making the effect dramatic. The findings open the way for more precise calculations of fission fragment distributions in heavy nuclei and may have far reaching consequences for the drip line nuclei, HI fusion reactions, and calculation of decay heat in the fission phenomenon.
Conservation of Isospin in Neutron-Rich Fission Fragments
Jain, Ashok Kumar; Maheshwari, Bhoomika
2014-01-01
On the occasion of the $75^{th}$ anniversary of the fission phenomenon, we present a surprisingly simple result which highlights the important role of isospin and its conservation in neutron rich fission fragments. We have analysed the fission fragment mass distribution from two recent heavy-ion reactions $^{238}$U($^{18}$O,f) and $^{208}$Pb($^{18}$O,f) as well as a thermal neutron fission reaction $^{245}$Cm(n$^{th}$,f). We find that the conservation of the total isospin explains the overall trend in the observed relative yields of fragment masses in each fission pair partition. The isospin values involved are very large making the effect dramatic. The findings open the way for more precise calculations of fission fragment distributions in heavy nuclei and may have far reaching consequences for the drip line nuclei, HI fusion reactions, and calculation of decay heat in the fission phenomenon.
International Nuclear Information System (INIS)
The fission cross section of 233U has been calculated using a new version of the statistical model and recent data for inelastic scattering levels and fission barrier parameters. The calculation accurately reproduces the experimental fission cross section. The calculated partial cross section for fission through different saddle point states (JKπ) has been used in the explanation of structure in average number of fission prompt neutrons anti νsub(p) and average total fission fragment kinetic energy anti Esub(k) and the energy dependence of the fission fragment anisotropy
Neutron Damage in the Plasma Chamber First Wall of the GCFTR-2 Fusion-Fission Hybrid Reactor
Pinto, L. N.; Gonnelli, E.; Rossi, P. C. R.; Carluccio, T.; dos Santos, A.
2015-07-01
The successful development of energy-conversion machines based on either nuclear fission or fusion is completely dependent on the behaviour of the engineering materials used to construct the fuel containment and primary heat extraction systems. Such materials must be designed in order to maintain their structural integrity and dimensional stability in an environment involving high temperatures and heat fluxes, corrosive media, high stresses and intense neutron fluxes. However, despite the various others damage issues, such as the effects of plasma radiation and particle flux, the neutron flux is sufficiently energetic to displace atoms from their crystalline lattice sites. It is clear that the understanding of the neutron damage is essential for the development and safe operation of nuclear systems. Considering this context, the work presents a study of neutron damage in the Gas Cooled Fast Transmutation Reactor (GCFTR-2) driven by a Tokamak D-T fusion neutron source of 14.03 MeV. The theoretical analysis was performed by MCNP-5 and the ENDF/B-VII.1 neutron data library. A brief discussion about the determination of the radiation damage is presented, along with an analysis of the total neutron energy deposition in seven points through the material of the plasma source wall (PSW), in which was considered the HT-9 steel. The neutron flux was subdivided into three energy groups and their behaviour through the material was also examined.
International Nuclear Information System (INIS)
In the framework of the present thesis by comparison of the experimental measurement data obtained by means of the detector system DIOGENES with calculated trajectories possible scission-point configurations of the fissioning nucleus should be stated. Special interest was dedicated to the evaluation of the so-called particle-accompanied fission in which beside the two fission fragments yet a light particle is additionally emitted. The initial conditions of a fission searched for are obtained by means of trajectory calculations which yield for assumed starting values the physical quantities as result which are also experimental accessible like final energies of all three contributing particles and angle between the light particle and the light fragment. The calculations were performed both for spherical and for rotational-ellipsoidally deformed fragments. All calculations were performed including the Coulomb and nuclear interaction forces between the three contributing nuclei, the fission fragment, and the α particle. (orig./HSI)
ZZ ORYX-E/38B, Group Constant Library from ENDF/B Fission Product Data for ORIGEN Calculation
International Nuclear Information System (INIS)
1 - Nature of physical problem solved: Format: ORIGEN; Number of groups: 124 energy groups; Nuclides: H, He, Li, Be, B, C, N, O, F, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Po. Origin: ENDF/B-IV; Weighting spectrum: Maxwellian (1/E) fission spectrum with a one percent tolerance. ORYX-E increases the versatility of the program ORIGEN , the isotope generation and depletion code package by providing basic cross section and decay information for light element, fission-product, and actinide nuclides. This data library package results from data compiled for ORNL Chemical Technology Division's work with ORIGEN and from a 2-year effort of the cross section evaluation working group (CSEWG) fission product task force. 2 - Method of solution: The data is generated from ENDF/B-IV and is formatted for input to the ORIGEN code. Applications include calculations for waste projection, decay heat, nuclear safeguards, and fuel cycle economics. The data library is generated from the ENDF/B-IV fission product data. The capture cross section of all fission product nuclides for which capture cross section information is given (about 180 nuclides) were processed into 124 energy groups using MINX. Multigroup cross sections were generated at 0 degrees with infinite dilution and one broad thermal group. Fine group data was generated using a Maxwellian (1/E) fission spectrum with a one percent tolerance
Shielding calculation of a hot cell for the processing of fission products
International Nuclear Information System (INIS)
A dose rate estimation is made for an operator of a lead wall, fission products processing hot cell, in a distance of 50 cm from the emission source, at Brazilian Institute of Nuclear Engineering (IEN). (L.C.J.A.)
Calculations of cross sections for the synthesis of super-heavy nuclei in cold fusion reactions
International Nuclear Information System (INIS)
The fusion cross sections are considered to be given by the product of three factors: the cross section to overcome the Coulomb barrier, the probability for the resulting system to reach the compound nucleus configuration by diffusion, and the probability for the compound nucleus to survive fission. The first and third factors are treated by more or less conventional equations, and the second by Brownian diffusion in one dimension. Adjusting one free parameter in the theory one can reproduce the twelve measured cross sections to within a factor of two. (author)
International Nuclear Information System (INIS)
In a Monte Carlo (MC) eigenvalue calculation, it is well known that the apparent variance of a local tally such as pin power differs from the real variance considerably. The MC method in eigenvalue calculations uses a power iteration method. In the power iteration method, the fission matrix (FM) and fission source density (FSD) are used as the operator and the solution. The FM is useful to estimate a variance and covariance because the FM can be calculated by a few cycle calculations even at inactive cycle. Recently, S. Carney have implemented the higher order fission matrix (HOFM) capabilities into the MCNP6 MC code in order to apply to extend the perturbation theory to second order. In this study, the HOFM capability by the Hotelling deflation method was implemented into McCARD and used to predict the behavior of a real and apparent SD ratio. In the simple 1D slab problems, the Endo's theoretical model predicts well the real to apparent SD ratio. It was noted that the Endo's theoretical model with the McCARD higher mode FS solutions by the HOFM yields much better the real to apparent SD ratio than that with the analytic solutions. In the near future, the application for a high dominance ratio problem such as BEAVRS benchmark will be conducted
Numerical calculation of current leads for fusion magnets
International Nuclear Information System (INIS)
Current leads for high currents up to 50 kA needed for superconducting fusion magnets have to be optimized with respect to heat losses at the cold and warm end to minimize the refrigerator power. Therefore a computer code named CURLEAD was written which solves the one-dimensional heat equation for the current lead and the energy balance for the helium coolant simultaneously. This paper describes the physical models and the mathematics used in this program. Special attention has been given to the discussion of the effect of parameter changes on the heat losses and the temperature distribution as well. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Tone, Tatsuzo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
2001-03-01
Overview of the historical evolution of nuclear energy systems development and related activities in JAERI is given in the report. This report reviews the research and development for light water reactor, fast breeder reactor, high temperature gas reactor, fusion reactor and utilization of accelerator-based neutron source. (author)
International Nuclear Information System (INIS)
Overview of the historical evolution of nuclear energy systems development and related activities in JAERI is given in the report. This report reviews the research and development for light water reactor, fast breeder reactor, high temperature gas reactor, fusion reactor and utilization of accelerator-based neutron source. (author)
Study of fusion-fission dynamics in 19F+238U reaction
Dubey, R.; Sugathan, P.; Jhingan, A.; Kaur, Gurpreet; Mukul, Ish; Siwal, Davinder; Saneesh, N.; Banerjee, Tathagata; Yadav, Abhishek; Thakur, Meenu; Mahajan, Ruchi; Chaterjee, M. B.
2016-05-01
Mass angle distribution measurements for 19F+238U reaction were carried out around the sub barrier energies. Mass angle correlation has not been observed at above and below the fusion barrier in present reaction. This infer the minimal presence of non compound like events at these bombarding energies range.
Decrease of the CANDU spent nuclear waste inventories in fusion-fission (hybrid) reactors
International Nuclear Information System (INIS)
The possibility of spent nuclear fuel rejuvenation in fusion reactors is investigated for both (D,T) and catalyzed (D,D) modes. The analysis is conducted for a CANDU spent nuclear fuel which was used up to a total enrichment grade of 0.418%. The behavior of the spent fuel is observed during 48 months for discrete time intervals of Δt = 6 months. The cooling of the fissile fuel zone is considered with three different coolants, notably gas (preferably He), Flibe (Li2BeF4) and natural lithium. A rejuvenation period of 8 months is evaluated for a final fissile fuel enrichment grade of 1% for all coolant types in the fissile zone under a first-wall fusion neutron current load of 1,014 (2.45-MeV n/cm2.s) and 1,014 (14.1-MeV n/cm2.x), corresponding to 2.64 MW/m2 by a plant factor of 75% for the catalyzed (D,D) fusion reactor mode. The rejuvenation period increases to 12 months for the same fissile fuel enrichment grade using the (D,T) fusion reactor mode under a first-wall fusion neutron current load of 1,014 (2.45-MeV n/cm2.s), corresponding to 2.25 MW/m2 by a plant factor of 75%. This enrichment would be sufficient for a re-utilization in a CANDU reactor
International Nuclear Information System (INIS)
Fission and total level densities modelling approach was developed. Neutron-induced fission cross section data for incident energies from 10 keV up to emissive fission threshold were employed to extract level density and fission barrier parameters. In particular, fission barrier parameters (inner barrier height, outer barrier height, curvatures) were extracted for altogether 49 isotopes of Th, Pa, U, Np, Pu, Am, Cm, Bk, and Cf. The adopted level density modelling approach and fission barrier parametrization was supported by calculations of fission cross section data above the emissive fission threshold, up to 20 MeV neutron incident energy. (author)
Directory of Open Access Journals (Sweden)
K. Nishio
2015-09-01
Full Text Available Mass distributions of fission fragments from the compound nuclei 180Hg and 190Hg formed in fusion reactions 36Ar + 144Sm and 36Ar + 154Sm, respectively, were measured at initial excitation energies of E⁎(Hg180=33–66 MeV and E⁎(Hg190=48–71 MeV. In the fission of 180Hg, the mass spectra were well reproduced by assuming only an asymmetric-mass division, with most probable light and heavy fragment masses A¯L/A¯H=79/101. The mass asymmetry for 180Hg agrees well with that obtained in the low-energy β+/EC-delayed fission of 180Tl, from our earlier ISOLDE(CERN experiment. Fission of 190Hg is found to proceed in a similar way, delivering the mass asymmetry of A¯L/A¯H=83/107, throughout the measured excitation energy range. The persistence as a function of excitation energy of the mass-asymmetric fission for both proton-rich Hg isotopes gives strong evidence for the survival of microscopic effects up to effective excitation energies of compound nuclei as high as 40 MeV. This behavior is different from fission of actinide nuclei and heavier mercury isotope 198Hg.
Pomorski, K; Surowiec, A; Kowal, M; Bartel, J; Dietrich, K G; Richert, J; Schmitt, C; Benoit, B; De Goes-Brennard, E; Donadille, L; Badimon, C
2000-01-01
We present a comparison of our model treating fission dynamics in conjunction with light-particle ( n,p,alpha ) evaporation with the available experimental data for the nuclei sup 1 sup 2 sup 6 Ba, sup 1 sup 8 sup 8 Pt and three isotopes of the element Z=110 . The dynamics of the symmetric fission process is described through the solution of a classical Langevin equation for a single collective variable characterizing the nuclear deformation along the fission path. A microscopic approach is used to evaluate the emission rates for prefission light particles. Entrance-channel effects are taken into account by generating an initial spin distribution of the compound nucleus formed by the fusion of two deformed nuclei with different relative orientations.
Zamponi, Nahuel; Billoni, Orlando V; Cannas, Sergio A; Helguera, Pablo R; Chialvo, Dante R
2016-01-01
Mitochondrial networks have been shown to exhibit a variety of complex behaviors, including cell-wide oscillations of mitochondrial energy states, as well as a phase transition in response to oxidative stress. Since functional status and structural properties are often intertwined, in this work we look at the structural properties of the organelle in normal mouse embryonic fibroblasts, describing its most relevant features. Subsequently we manipulated mitochondrial morphology using two interventions with opposite effects: over-expression of mitofusin 1, a protein that promotes mitochondria fusion, and paraquat treatment, a compound that induces mitochondrial fragmentation due to oxidative stress. Quantitative analysis of the organelle's structural clusters revealed that healthy mitochondrial networks were in a status intermediate between the extremes of highly fragmented and completely fusioned networks. This was confirmed by a comparison of our empirical findings with those of a recently described computatio...
The integration of D-cycle tokamaks with decentralized small fusion and fission reactors
International Nuclear Information System (INIS)
A reaction physics analysis is undertaken of the conceptual characteristics of a large tokamak fusion reactor, equipped with a breeding blanket and operating on the deuterium cycle, supplying helium-3 fuel for numerous small D-3He fusion satellite reactors, as well as fissile fuel for selfregulating small nuclear heat sources. A range of systems parameters consistent with current experimental projections and design ranges are incorporated in the analysis. It is found that the intrinsic reaction and energetics complementarity provides a scientific basis for further development of this concept. The two dominant and particularly appealing features of this concept are the expanded latitude in system design and the prospects of introducing small decentralized nuclear energy sources for remote and special purpose applications. (orig.)
Williams, J. R.
1974-01-01
Air pollution resulting from the use of fossil fuels is discussed. Phenomena relating to the emission of CO2 such as the greenhouse effect and multiplier effect are explored. Particulate release is also discussed. The following recommendations are made for the elimination of fossil fuel combustion products in the United States: development of nuclear breeder reactors, use of solar energy systems, exploration of energy alternatives such as geothermal and fusion, and the substitution of coal for gas and oil use.
Eslamizadeh, H.
2015-09-01
The fission probability, pre-scission neutron, proton and alpha multiplicities, anisotropy of fission fragment angular distribution and the fission time have been calculated for the compound nuclei 200Pb and 197Tl based on the modified statistical model and four-dimensional dynamical model. In dynamical calculations, dissipation was generated through the chaos weighted wall and window friction formula. The projection of the total spin of the compound nucleus to the symmetry axis, K, was considered as the fourth-dimension in Langevin dynamical calculations. In our dynamical calculations, we have used a constant dissipation coefficient of K, {γ }K=0.077{({{MeV}} {{zs}})}-{1/2}, and a non-constant dissipation coefficient to reproduce the above-mentioned experimental data. Comparison of the theoretical results of the fission probability and pre-scission particle multiplicities with the experimental data showed that the difference between the results of both dynamical models is small whereas, for the anisotropy of fission fragment angular distribution, it is slightly large. Furthermore, comparison of the results of the modified statistical model with the above-mentioned experimental data showed that with choosing appropriate values of the temperature coefficient of the effective potential, λ , and the scaling factor of the fission-barrier height, {r}s, the experimental data were satisfactorily reproduced.
Competition between quasi-molecular resonances and fusion-fission in light dinuclear systems
Energy Technology Data Exchange (ETDEWEB)
Beck, C. [Institut de Recherches Subatomiques, Universite Louis Pasteur, Strasbourg (France)
1999-05-01
The results presented in this paper clearly suggest that a coherent framework may exist which connects the topics of heavy-ion molecular resonances, hyperdeformation effects, and fission shape isomerism. New data on particle-particle-{gamma} triple coincidences of the {sup 28}Si + {sup 28}Si reaction at a beam energy corresponding to the population of a conjectured J{sup {pi}} = 38{sup +} resonance in {sup 56}Ni are presented. The absence of alignment of the spins of the outgoing fragments with respect to the orbital angular momentum is found to be in contrast with the alignment as measured for the {sup 24}Mg +{sup 24}Mg resonances. A molecular-model picture is presented to suggest a ``butterfly`` motion of two oblate {sup 28}Si nuclei interacting in a equator-to-equator molecular configuration. (author) 17 refs, 7 figs
Blanket design and performance for the LOTUS fusion-fission hybrid test facility
International Nuclear Information System (INIS)
This report summarizes the results of studies performed during 1982 to design an optimized blanket for the initial series of experiments to be conducted in the LOTUS test facility at the Swiss Federal Institute of Technology in Lausanne (EPFL). The experiments are expected to begin in early 1984. An Overview of different hybrid blanket design concepts proposed to date is first given. The technological and economic implications of the different blanket design philosophies are discussed to provide the basis and rationale for the thorium fast-fission blanket design concept selected for the first series of experiments. Detailed description, dimensions, and characteristics of the selected blanket design are given. The neutronic optimization studies on which the design is based are described in detail. Instrumentation and measurement techniques to be used in LOTUS are described elsewhere
Radiationless decay, fission and fusion of excitons in irradiated molecular crystals
International Nuclear Information System (INIS)
The creation and evolution of excited states in ionizing particle tracks were investigated. The passage of high energy ionizing particles in molecular crystals results in the formation of highly excited states which energy is generally above the molecular ionization potential. The theory of non radiative transitions, which describes the transitions from the highly excited states to the lowest singlet and triplet excitons S1 and T1 is developed. Among these non radiative transitions, the fission of singlet excitons into two singlet or triplet excitons of lower energies is studied experimentally. These results and a kinematics study of the S1 and T1 excitons in ionizing particle tracks were used to get a complete description of the scintillation. These results are in good agreement with the experimental measurements on the scintillation
3D Neutronic Analysis in MHD Calculations at ARIES-ST Fusion Reactors Systems
Hançerliogulları, Aybaba; Cini, Mesut
2013-10-01
In this study, we developed new models for liquid wall (FW) state at ARIES-ST fusion reactor systems. ARIES-ST is a 1,000 MWe fusion reactor system based on a low aspect ratio ST plasma. In this article, we analyzed the characteristic properties of magnetohydrodynamics (MHD) and heat transfer conditions by using Monte-Carlo simulation methods (ARIES Team et al. in Fusion Eng Des 49-50:689-695, 2000; Tillack et al. in Fusion Eng Des 65:215-261, 2003) . In fusion applications, liquid metals are traditionally considered to be the best working fluids. The working liquid must be a lithium-containing medium in order to provide adequate tritium that the plasma is self-sustained and that the fusion is a renewable energy source. As for Flibe free surface flows, the MHD effects caused by interaction with the mean flow is negligible, while a fairly uniform flow of thick can be maintained throughout the reactor based on 3-D MHD calculations. In this study, neutronic parameters, that is to say, energy multiplication factor radiation, heat flux and fissile fuel breeding were researched for fusion reactor with various thorium and uranium molten salts. Sufficient tritium amount is needed for the reactor to work itself. In the tritium breeding ratio (TBR) >1.05 ARIES-ST fusion model TBR is >1.1 so that tritium self-sufficiency is maintained for DT fusion systems (Starke et al. in Fusion Energ Des 84:1794-1798, 2009; Najmabadi et al. in Fusion Energ Des 80:3-23, 2006).
General Description of Fission Observables - JEFF Report 24. GEF Model
International Nuclear Information System (INIS)
The Joint Evaluated Fission and Fusion (JEFF) Project is a collaborative effort among the member countries of the OECD Nuclear Energy Agency (NEA) Data Bank to develop a reference nuclear data library. The JEFF library contains sets of evaluated nuclear data, mainly for fission and fusion applications; it contains a number of different data types, including neutron and proton interaction data, radioactive decay data, fission yield data and thermal scattering law data. The General fission (GEF) model is based on novel theoretical concepts and ideas developed to model low energy nuclear fission. The GEF code calculates fission-fragment yields and associated quantities (e.g. prompt neutron and gamma) for a large range of nuclei and excitation energy. This opens up the possibility of a qualitative step forward to improve further the JEFF fission yields sub-library. This report describes the GEF model which explains the complex appearance of fission observables by universal principles of theoretical models and considerations on the basis of fundamental laws of physics and mathematics. The approach reveals a high degree of regularity and provides a considerable insight into the physics of the fission process. Fission observables can be calculated with a precision that comply with the needs for applications in nuclear technology. The relevance of the approach for examining the consistency of experimental results and for evaluating nuclear data is demonstrated. (authors)
International Nuclear Information System (INIS)
A multi-functional experimental fusion-fission hybrid reactor concept named FDS-MFX, which is based on viable fusion and fission technologies, has been proposed. Three-stage tests will be carried out successively, in which the tritium breeding blanket, uranium-fueled blanket and spent-fuel-fueled blanket will be utilized respectively. In this paper, the design optimization for the layout and the size of high enriched uranium modules in later stage of uranium-fueled blanket has been performed. Finally, proposing a preliminary three-dimension neutronics design with maximum average Power Density (PDmax) 100 MW/ m3, loaded mass of the 235U 1000 kg and TBR (Tritium Breeding Ratio) 1.05. (authors)
Quasiﬁssion and Fusion-Fission Competition in 32S + 184W Reaction
Manganaro M.; Mandaglio G.; Nasirov A.K.; Yang F.; Liu Z.H.; Lin C.J.; Zhang H.Q.; Zhang C.L.; Giardina G.
2011-01-01
The angular distribution of ﬁssion fragments for the 32S+184W reaction at center-of-mass energies of 118.8, 123.1, 127.3, 131.5, 135.8, 141.1 and 144.4 MeV were measured. The experimental ﬁssion excitation function is obtained. The fragment angular anisotropy is found by extrapolating the ﬁssion angular distributions. The measured ﬁssion cross sections are decomposed into fusion-ﬁssion, quasiﬁssion and fast-ﬁssion contributions by the dinuclear system model. The total evaporation residue and...
Microstructural origins of yield strength changes in AISI 316 during fission or fusion irradiation
International Nuclear Information System (INIS)
The changes in yield strength of AISI 316 irradiated in breeder reactors have been successfully modeled in terms of concurrent changes in microstructural components. Two new insights involving the strength contributions of voids and Frank loops have been incorporated into the hardening models. Both the radiation-induced microstructure and the yield strength exhibit transients which are then followed by saturation at a level dependent on the irradiation temperature. Extrapolation to anticipated fusion behavior based on microstructural comparisons leads to the conclusion that the primary influence of transmutational differences is only to alter the transient behavior and not the saturation level of yield strength
International Nuclear Information System (INIS)
For energy demand in the economic development of China in 21 Century, for seeking the strategy to develop nuclear energy in China, according to the nuclear resources in China and the perspective of international nuclear technology development, the optimization of the combination of three kinds of advanced reactors, namely, HTGR, FBR, and fusion-fission hybrid reactors in the development of nuclear energy in China was investgated. Three alternative stra tegies with different priorities were suggested
International Nuclear Information System (INIS)
This report describes the calculation procedure of the TRANCS code, which deals with fission product transport in fuel rod of high temperature gas-cooled reactor (HTGR). The fundamental equation modeled in the code is a cylindrical one-dimensional diffusion equation with generation and decay terms, and the non-stationary solution of the equation is obtained numerically by a finite difference method. The generation terms consist of the diffusional release from coated fuel particles, recoil release from outer-most coating layer of the fuel particle and generation due to contaminating uranium in the graphite matrix of the fuel compact. The decay term deals with neutron capture as well as beta decay. Factors affecting the computation error has been examined, and further extention of the code has been discussed in the fields of radial transport of fission products from graphite sleeve into coolant helium gas and axial transport in the fuel rod. (author)
Use of ELOCA.Mk5 to calculate transient fission product release from CANDU fuel elements
International Nuclear Information System (INIS)
A change in fuel element power output, or a change in heat transfer conditions, will result in an immediate change in the temperature distribution in a fuel element. The temperature distribution change will be accompanied by concomitant changes in fuel stress distribution that lead, in turn, to a release of fission products to the fuel-to-sheath gap. It is important to know the inventory of fission products in the fuel-to-sheath gap, because this inventory is a major component of the source term for many postulated reactor accidents. ELOCA.Mk5 is a FORTRAN-77 computer code that has been developed to estimate transient releases to the fuel-to-sheath gap in CANDU reactors. ELOCA.Mk5 is an integration of the FREEDOM fission product release model into the ELOCA fuel element thermo-mechanical code. The integration of FREEDOM into ELOCA allows ELOCA.Mk5 to model the feedback mechanisms between the fission product release and the thermo-mechanical response of the fuel element. This paper describes the physical model, gives details of the ELOCA.Mkt code, and describes the validation of the model. We demonstrate that the model gives good agreement with experimental results for both steady state and transient conditions
Main restrictions in the synthesis of new superheavy elements: quasifission or/and fusion-fission
Nasirov, Avazbek; Mandaglio, Giuseppe; Giardina, Giorgio; Muminov, Akhtam; Kim, Youngman
2013-01-01
The synthesis of superheavy elements stimulates the effort to study the peculiarities of the complete fusion with massive nuclei and to improve theoretical models in order to extract knowledge about reaction mechanism in heavy ion collisions at low energies. We compare the theoretical results of the compound nucleus (CN) formation and evaporation residue (ER) cross sections obtained for the $^{48}$Ca+$^{248}$Cm and $^{58}$Fe+$^{232}$Th reactions leading to the formation of the isotopes $A=296$ and $A=290$, respectively, of the new superheavy element Lv ($Z=116$). The ER cross sections, which can be measured directly, are determined by the complete fusion and survival probabilities of the heated and rotating compound nucleus. That probabilities can not be measured unambiguously but the knowledge about them is important to study the formation mechanism of the observed products. For this aim, the $^{48}$Ca+$^{249}$Cf and $^{64}$Ni+$^{232}$Th reactions have been considered too. The use of the mass values of super...
Demekhina, N. A.; Karapetyan, G. S.; Balabekyan, A. R.
2014-01-01
The cross sections for the binary fission of 197Au, 181Ta and 209Bi targets induced by 11B ions were measured at intermediate energies. The fission products cross sections were studied by means of activation analysis in off-line regime observed gamma-ray spectra. The fission cross section is reconstructed on the basis of charge and mass distribution of the fission products.
Henry, E; Nyibule, S; Quinlan, M; Schroder, W U; Ademard, G; Amorini, F; Auditore, L; Beck, C; Berceanu, I; Bonnet, E; Borderie, B; Cardella, G; Chbihi, A; Colonna, M; De Filippo, E; DOnofrio, A; Frankland, J D; Geraci, E; La Guidara, E; La Commara, M; Lanzalone, G; Lautesse, P; Lebhertz, D; Neindre, N Le; Lombardo, I; Loria, D; Mazurek, K; Pagano, A; Papa, M; Piasecki, E; Pirrone, S; Politi, G; Porto, F; Rizzo, F; Rosato, E; Rusotto, P; Spadaccini, G; Trifiro, A; Trimarchi, M; Verde, G; Vigilante, M; Wieleczko, J P
2014-01-01
An analysis of experimental data from the inverse-kinematics ISODEC experiment on 78Kr+40Ca reaction at a bombarding energy of 10 AMeV has revealed signatures of a hitherto unknown reaction mechanism, intermediate between the classical damped binary collisions and fusion-fission, but also substantially different from what is being termed in the literature as fast fission or quasi fission. These signatures point to a scenario where the system fuses transiently while virtually equilibrating mass asymmetry and energy and, yet, keeping part of the energy stored in a collective shock-imparted and, possibly, angular momentum bearing form of excitation. Subsequently the system fissions dynamically along the collision or shock axis with the emerging fragments featuring a broad mass spectrum centered around symmetric fission, relative velocities somewhat higher along the fission axis than in transverse direction, and virtually no intrinsic spin. The class of massasymmetric fission events shows a distinct preference fo...
Next generation laser optics for a hybrid fusion-fission power plant
Energy Technology Data Exchange (ETDEWEB)
Stolz, C J; Latkowski, J T; Schaffers, K I
2009-09-10
The successful completion of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL), followed by a campaign to achieve ignition, creates the proper conditions to begin exploring what development work remains to construct a power plant based on Inertial Confinement Fusion (ICF) technology. Fundamentally, two distinct NIF laser properties must be overcome. The repetition rate must increase from a shot every four hours to several shots per second. Additionally, the efficiency of converting electricity to laser light must increase by 20x to roughly 10 percent. Solid state diode pumped lasers, commercially available for table top applications, have adequate repetition rates and power conversion efficiencies, however, they operate at a tiny fraction of the required energy for an ICF power plant so would need to be scaled in energy and aperture. This paper describes the optics and coatings that would be needed to support this type of laser architecture.
A spallation-based irradiation test facility for fusion and future fission materials
Samec, K; Kadi, Y; Luis, R; Romanets, Y; Behzad, M; Aleksan, R; Bousson, S
2014-01-01
The EU’s FP7 TIARA program for developing accelerator-based facilities has recently demonstrated the unique capabilities of a compact and powerful spallation source for irradiating advanced nuclear materials. The spectrum and intensity of the neutron flux produced in the proposed facility fulfils the requirements of the DEMO fusion reactor for ITER, ADS reactors and also Gen III / IV reactors. Test conditions can be modulated, covering temperature from 400 to 550°C, liquid metal corrosion, cyclical or static stress up to 500 MPa and neutron/proton irradiation damage of up to 25 DPA per annum. The entire “TMIF” facility fits inside a cube 2 metres on a side, and is dimensioned for an accelerator beam power of 100 kW, thus reducing costs and offering great versatility and flexibility.
International Nuclear Information System (INIS)
This work is devoted to the development of calculational models, on the basis of which it is possible to evaluate proliferation protection for various fissionable materials. The main physical, kinematic and thermal processes that take place in a hypothetical nuclear explosive device (HNED) are simulated. Consideration is referred both to gun-type and implosion-type HNED. The objective of the gun-type HNED model is to estimate the maximum speed at which subcritical masses can be assembled. At the basis of the model it is laid the assumption that the movement of the projectile in the barrel is uniformly accelerated. To estimate maximum allowable explosive gas pressure the model of A. V. Gadolin (proposed in 1852 year) is used (1). The addition of spontaneous neutron source (for example, 232U with beryllium admixture) into nuclear material (U) in order to provide a premature initiation of chain reaction (pre-detonation) was analyzed. Required neutron source strength and fraction of 232U with beryllium admixture for a pre-detonation were evaluated. The principle design of implosion-type HNED is based on the model which was proposed by Doctor G. Kessler (2). The implosion-type HNED consists of a central plutonium charge surrounded by spherical layers of natural uranium, aluminum and chemical high explosive (HE). To protect nuclear material (Pu) it is suggested (2) to add some amount of radioactive isotope (238Pu), the alpha decay heat of which could overheat HNED and render it non-functional. When heated up, HNED loses its effectiveness mainly due to the high-temperature instability of HE (meltdown, pyrolysis and self-ignition). A calculational model of non-stationary warm-up of implosive-type HNED has been developed in order to evaluate the rate of loss of its effectiveness for different isotopic compositions of plutonium and for different methods of heat removal. The paper presents the obtained results in numerical studies of the transient behavior of temperature
Energy Technology Data Exchange (ETDEWEB)
Shmelev, A.N.; Kulikov, E.G.; Apse, V.A.; Kulikov, G.G. [Moscow Engineering Physics Institute (State University), Kashirskoe shosse 31, Moscow, 115409 (Russian Federation)
2009-06-15
This work is devoted to the development of calculational models, on the basis of which it is possible to evaluate proliferation protection for various fissionable materials. The main physical, kinematic and thermal processes that take place in a hypothetical nuclear explosive device (HNED) are simulated. Consideration is referred both to gun-type and implosion-type HNED. The objective of the gun-type HNED model is to estimate the maximum speed at which subcritical masses can be assembled. At the basis of the model it is laid the assumption that the movement of the projectile in the barrel is uniformly accelerated. To estimate maximum allowable explosive gas pressure the model of A. V. Gadolin (proposed in 1852 year) is used (1). The addition of spontaneous neutron source (for example, {sup 232}U with beryllium admixture) into nuclear material (U) in order to provide a premature initiation of chain reaction (pre-detonation) was analyzed. Required neutron source strength and fraction of {sup 232}U with beryllium admixture for a pre-detonation were evaluated. The principle design of implosion-type HNED is based on the model which was proposed by Doctor G. Kessler (2). The implosion-type HNED consists of a central plutonium charge surrounded by spherical layers of natural uranium, aluminum and chemical high explosive (HE). To protect nuclear material (Pu) it is suggested (2) to add some amount of radioactive isotope ({sup 238}Pu), the alpha decay heat of which could overheat HNED and render it non-functional. When heated up, HNED loses its effectiveness mainly due to the high-temperature instability of HE (meltdown, pyrolysis and self-ignition). A calculational model of non-stationary warm-up of implosive-type HNED has been developed in order to evaluate the rate of loss of its effectiveness for different isotopic compositions of plutonium and for different methods of heat removal. The paper presents the obtained results in numerical studies of the transient behavior
EPFL (Swiss) Fusion-Fission Hybrid Experiment. Progress report No. 13, February 1-April 31, 1985
International Nuclear Information System (INIS)
Discussions were completed by EPFL personnel concerning the Lithium Blanket Module, experiments with the Haefely source spectra with the neutron telescope, the development of a NE-213 neutron spectrometer, and plasma model calculations. 3 refs., 1 fig., 1 tab
International Nuclear Information System (INIS)
This series of 7 digest booklets present the bases of the nuclear physics and of the nuclear energy: 1 - the atom (structure of matter, chemical elements and isotopes, the four fundamental interactions, nuclear physics); 2 - radioactivity (definition, origins of radioelements, applications of radioactivity); 3 - man and radiations (radiations diversity, biological effects, radioprotection, examples of radiation applications); 4 - energy (energy states, different forms of energy, characteristics); 5 - nuclear energy: fusion and fission (nuclear energy release, thermonuclear fusion, nuclear fission and chain reaction); 6 - operation of a nuclear reactor (nuclear fission, reactor components, reactor types); 7 - nuclear fuel cycle (nuclear fuel preparation, fuel consumption, reprocessing, wastes management). (J.S.)
Energy Technology Data Exchange (ETDEWEB)
Cabrera, Carlos Eduardo Velasquez
2015-07-01
A fission-fusion hybrid reactor is proposed for recycling and transmutation of highly radioactive waste. Two fusion systems were evaluated. A Tokamak, based on magnetic confinement, and another based on inertial confinement. These systems have been modified and designed to place a transmutation layer loaded with transuranic elements from spent fuel of nuclear power plants. The transmutation layer is the first presented in specific literature to be used with fuel reprocessed by the method UREX + and further spiked with depleted uranium or thorium to reduce the amount of fissile material in order to keep a subcritical system. The evaluations were carried out by varying geometric parameters such as the thickness of transmutation layer and the radius of the fuel rod. Depending on the case this variations increase the efficiency to reduce the transuranic contained in the fuel. The results show the possibility of reducing the transuranic for each model and transmutation efficiency compared to the initial amount of recycled fuel for each fusion reactor. Furthermore, a comparison of both hybrid fusion-fission systems is performed in order to find the best system to reduce transuranics efficiently. (author)
Umar, A. S.; Oberacker, V. E.
2008-01-01
We present a fully microscopic study of the $^{16}$O+$^{208}$Pb fusion using the density-constrained time-dependent Hartree-Fock theory. The calculated fusion cross-sections are in good agreement with the experimental data for the entire energy range indicating that the incorporation of dynamical effects is crucial in describing heavy-ion fusion.
Development of ODS FeCrAl for Compatibility in Fusion and Fission Energy Applications
Pint, B. A.; Dryepondt, S.; Unocic, K. A.; Hoelzer, D. T.
2014-12-01
Oxide dispersion strengthened (ODS) FeCrAl alloys with 12-15% Cr are being evaluated for improved compatibility with Pb-Li for a fusion energy application and with high temperature steam for a more accident-tolerant light water reactor fuel cladding application. A 12% Cr content alloy showed low mass losses in static Pb-Li at 700°C, where a LiAlO2 surface oxide formed and inhibited dissolution into the liquid metal. All the evaluated compositions formed a protective scale in steam at 1200°C, which is not possible with ODS FeCr alloys. However, most of the compositions were not protective at 1400°C, which is a general and somewhat surprising problem with ODS FeCrAl alloys that is still being studied. More work is needed to optimize the alloy composition, microstructure and oxide dispersion, but initial promising tensile and creep results have been obtained with mixed oxide additions, i.e. Y2O3 with ZrO2, HfO2 or TiO2.
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steels, and, (ii) to validate model prediction at the relevant scale and on the adequate system. The paper will present modelling results based on ab-initio calculation and the development of kinetic tools describing (i) phase stability of Fe-Cr alloy system taking magnetic effects explicitly into account, (ii) point defects energetics in transition metals and their recovery in α-Fe (iii) He and dpa accumulation, and (iv) dynamical properties of dislocations in α-Fe at low and high temperatures. Based on the successful progress of the currently on-going research programme, the Strategic Objectives defined for the next period 2010-2015 (http://www.efda.org/eu_fusion_programme/scientific_and_technical_publications.htm) will be presented and briefly discussed. (author)
International Nuclear Information System (INIS)
SOURCES 4A is a computer code that determines neutron production rates and spectra from (α,n) reactions, spontaneous fission, and delayed neutron emission due to the decay of radionuclides. The code is capable of calculating (α,n) source rates and spectra in four types of problems: homogeneous media (i.e., a mixture of α-emitting source material and low-Z target material), two-region interface problems (i.e., a slab of α-emitting source material in contact with a slab of low-Z target material), three-region interface problems (i.e., a thin slab of low-Z target material sandwiched between α-emitting source material and low-Z target material), and (α,n) reactions induced by a monoenergetic beam of α-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 43 actinides. The (α,n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 89 nuclide decay α-particle spectra, 24 sets of measured and/or evaluated (α,n) cross sections and product nuclide level branching fractions, and functional α-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code outputs the magnitude and spectra of the resultant neutron source. It also provides an analysis of the contributions to that source by each nuclide in the problem
Energy Technology Data Exchange (ETDEWEB)
Wilson, W. B. (William B.); Perry, R. T. (Robert T.); Shores, E. F. (Erik F.); Charlton, W. S. (William S.); Parish, Theodore A.; Estes, G. P. (Guy P.); Brown, T. H. (Thomas H.); Arthur, Edward D. (Edward Dana),; Bozoian, Michael; England, T. R.; Madland, D. G.; Stewart, J. E. (James E.)
2002-01-01
SOURCES 4C is a computer code that determines neutron production rates and spectra from ({alpha},n) reactions, spontaneous fission, and delayed neutron emission due to radionuclide decay. The code is capable of calculating ({alpha},n) source rates and spectra in four types of problems: homogeneous media (i.e., an intimate mixture of a-emitting source material and low-Z target material), two-region interface problems (i.e., a slab of {alpha}-emitting source material in contact with a slab of low-Z target material), three-region interface problems (i.e., a thin slab of low-Z target material sandwiched between {alpha}-emitting source material and low-Z target material), and ({alpha},n) reactions induced by a monoenergetic beam of {alpha}-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 44 actinides. The ({alpha},n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 107 nuclide decay {alpha}-particle spectra, 24 sets of measured and/or evaluated ({alpha},n) cross sections and product nuclide level branching fractions, and functional {alpha}-particle stopping cross sections for Z < 106. The delayed neutron spectra are taken from an evaluated library of 105 precursors. The code provides the magnitude and spectra, if desired, of the resultant neutron source in addition to an analysis of the'contributions by each nuclide in the problem. LASTCALL, a graphical user interface, is included in the code package.
Energy Technology Data Exchange (ETDEWEB)
NONE
2002-07-01
This series of 7 digest booklets present the bases of the nuclear physics and of the nuclear energy: 1 - the atom (structure of matter, chemical elements and isotopes, the four fundamental interactions, nuclear physics); 2 - radioactivity (definition, origins of radioelements, applications of radioactivity); 3 - man and radiations (radiations diversity, biological effects, radioprotection, examples of radiation applications); 4 - energy (energy states, different forms of energy, characteristics); 5 - nuclear energy: fusion and fission (nuclear energy release, thermonuclear fusion, nuclear fission and chain reaction); 6 - operation of a nuclear reactor (nuclear fission, reactor components, reactor types); 7 - nuclear fuel cycle (nuclear fuel preparation, fuel consumption, reprocessing, wastes management). (J.S.)
International Nuclear Information System (INIS)
Like other intense neutron sources fusion reactors have in principle a potential to be used for military purposes. Although the use of fissile material is usually not considered when thinking of fusion reactors (except in fusion-fission hybrid concepts) quantitative estimates about the possible production potential of future commercial fusion reactor concepts show that significant amounts of weapon grade fissile materials could be produced even with very limited amounts of source materials. In this talk detailed burnup calculations with VESTA and MCMATH using an MCNP model of the PPCS-A will be presented. We compare different irradiation positions and the isotopic vectors of the plutonium bred in different blankets of the reactor wall with the liquid lead-lithium alloy replaced by uranium. The technical, regulatory and policy challenges to manage the proliferation risks of fusion power will be addressed as well. Some of these challenges would benefit if addressed at an early stage of the research and development process. Hence, research on fusion reactor safeguards should start as early as possible and accompany the current research on experimental fusion reactors.
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The INDL/F-83 data library is a computerized library of evaluated neutron reaction data which has been assembled from a variety of other evaluated data files and is intended for use in fusion neutronics calculations of the International Tokamak Reactor (INTOR) Project. These data are available on magnetic tape from the IAEA Nuclear Data Section. (author)
Advanced model for the prediction of the neutron-rich fission product yields
Rubchenya V.A.; Gorelov D.; Jokinen A.; Penttilä H.; Äystö J.
2013-01-01
The consistent models for the description of the independent fission product formation cross sections in the spontaneous fission and in the neutron and proton induced fission at the energies up to 100 MeV is developed. This model is a combination of new version of the two-component exciton model and a time-dependent statistical model for fusion-fission process with inclusion of dynamical effects for accurate calculations of nucleon composition and excitation energy of the fissioning nucleus a...
Ichikawa, Takatoshi; 10.1143/JPSJ.79.074201
2010-01-01
We discuss the possibility of the non-one-neutron emission channels in the cold fusion reaction $^{70}$Zn + $^{209}$Bi to produce the element Z=113. For this purpose, we calculate the evaporation-residue cross sections of one-proton, radiative-capture, and two-neutron emissions relative to the one-neutron emission in the reaction $^{70}$Zn + $^{209}$Bi. To estimate the upper bounds of those quantities, we vary model parameters in the calculations, such as the level-density parameter and the height of the fission barrier. We conclude that the highest possibility is for the 2n reaction channel, and its upper bounds are 2.4$%$ and at most less than 7.9% with unrealistic parameter values, under the actual experimental conditions of [J. Phys. Soc. Jpn. {\\bf 73} (2004) 2593].
International Nuclear Information System (INIS)
We discuss the possibility of the non-one-neutron emission channels in the cold fusion reaction 70Zn+209Bi to produce the element Z=113. For this purpose, we calculate the evaporation-residue cross sections of one-proton, radiative-capture, and two-neutron emissions relative to the one-neutron emission in the reaction 70Zn+209Bi. To estimate the upper bounds of those quantities, we vary model parameters in the calculations, such as the level-density parameter and the height of the fission barrier. We conclude that the highest possibility is for the 2n reaction channel, and its upper bounds are 2.4% and at most less than 7.9% with unrealistic parameter values, under the actual experimental conditions of [J.Phys.Soc.Jpn.73(2004)2593]. (author)
Pandey, Naresh; Nobles, Christopher L; Zechiedrich, Lynn; Maresso, Anthony W; Silberg, Jonathan J
2015-05-15
Gene fission can convert monomeric proteins into two-piece catalysts, reporters, and transcription factors for systems and synthetic biology. However, some proteins can be challenging to fragment without disrupting function, such as near-infrared fluorescent protein (IFP). We describe a directed evolution strategy that can overcome this challenge by randomly fragmenting proteins and concomitantly fusing the protein fragments to pairs of proteins or peptides that associate. We used this method to create libraries that express fragmented IFP as fusions to a pair of associating peptides (IAAL-E3 and IAAL-K3) and proteins (CheA and CheY) and screened for fragmented IFP with detectable near-infrared fluorescence. Thirteen novel fragmented IFPs were identified, all of which arose from backbone fission proximal to the interdomain linker. Either the IAAL-E3 and IAAL-K3 peptides or CheA and CheY proteins could assist with IFP fragment complementation, although the IAAL-E3 and IAAL-K3 peptides consistently yielded higher fluorescence. These results demonstrate how random gene fission can be coupled to rational gene fusion to create libraries enriched in fragmented proteins with AND gate logic that is dependent upon a protein-protein interaction, and they suggest that these near-infrared fluorescent protein fragments will be suitable as reporters for pairs of promoters and protein-protein interactions within whole animals. PMID:25265085
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An analytically solvable model is used to study the potential barrier penetrability in the case when the gap parameter Δ is treated as a dynamical variable governed by the least action principle. It is found that, as compared to the standard (BCS) approach, the dynamical treatment of pairing results in a considerably weakened dependence of the fission barrier penetrability on the intensity of pairing correlations in the initial state (Δ0), on the barrier height, and on the energy of the initial state. On this basis, a more adequate explanation is proposed for typical order-of-magnitude values of the empirical hidrance factors for groun-state spontaneous fission of odd nuclei. It is also shown that a large enhancement of superfluidity in tunneling - the inherent effect of the dynamical treatment of pairing - strongly facilitates deeply subbarier fusion of complex nuclei. Finally, an analysis is given for the probability of spontaneous fission from K-isomeric quasiparticle (q-p) states in even-even heavy nuclei. The relative change of the partial spontaneous fission half-life in going from the ground-state to a high-spin q-p isomeric state, T*sf/Tsf, is found to be strongly dependent on whether or not there takes place the dynamically induced enhancement of superfluidity in tunneling. Measurements of T*sf/Tsf provide thus a unique possibility of verifying theoretical predictions about the strong, inverse-square dependence of the effective inertia associated with large-scale subbarrier rearrangements of nuclei
Directory of Open Access Journals (Sweden)
Nishio Katsuhisa
2013-12-01
Full Text Available Fission fragment mass distributions were measured in heavy-ion induced fissions using 238U target nucleus. The measured mass distributions changed drastically with incident energy. The results are explained by a change of the ratio between fusion and quasifission with nuclear orientation. A calculation based on a fluctuation dissipation model reproduced the mass distributions and their incident energy dependence. Fusion probability was determined in the analysis. Evaporation residue cross sections were calculated with a statistical model in the reactions of 30Si + 238U and 34S + 238U using the obtained fusion probability in the entrance channel. The results agree with the measured cross sections for seaborgium and hassium isotopes.
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This report presents the conceptual design and preliminary feasibility assessment for the hybrid blanket and power conversion system of the Mirror Hybrid Fusion-Fission Reactor. Existing gas-cooled fission reactor technology is directly applicable to the Mirror Hybrid Reactor. There are a number of aspects of the present conceptual design that require further design and analysis effort. The blanket and power conversion system operating parameters have not been optimized. The method of supporting the blanket modules and the interface between these modules and the primary loop helium ducting will require further design work. The means of support and containment of the primary loop components must be studied. Nevertheless, in general, the conceptual design appears quite feasible
International Nuclear Information System (INIS)
Based on the Fick's law the computer program FPDR has been developed to calculate the one-dimensional diffusion and release behavior of fission products in the graphite sleeves of the first and second OGL-1 fuel assembly. Through the comparison between the measured and calculated penetration profiles, the diffusion coefficient of 90Sr in the first fuel sleeve has been estimated to be (2 -- 5) x 10-13 m2/s; those of 137Cs and 90Sr in the second fuel sleeve around or larger than 1 x 10-12 m2/s, and --10-14 m2/s, respectively. The release of 90Sr from the second fuel sleeve is negligible; that of 137Cs depends linearly on its diffusion coefficient if the coefficient is larger than 10-12 m2/s, but practically does not depend on its evaporation parameter. (author)
Remarks on the fission barriers of super-heavy nuclei
Hofmann, S.; Heinz, S.; Mann, R.; Maurer, J.; Münzenberg, G.; Antalic, S.; Barth, W.; Dahl, L.; Eberhardt, K.; Grzywacz, R.; Hamilton, J. H.; Henderson, R. A.; Kenneally, J. M.; Kindler, B.; Kojouharov, I.; Lang, R.; Lommel, B.; Miernik, K.; Miller, D.; Moody, K. J.; Morita, K.; Nishio, K.; Popeko, A. G.; Roberto, J. B.; Runke, J.; Rykaczewski, K. P.; Scheidenberger, C.; Shaughnessy, D. A.; Stoyer, M. A.; Thörle-Pospiech, P.; Tinschert, K.; Trautmann, N.; Uusitalo, J.; Yeremin, A. V.
2016-04-01
Shell-correction energies of super-heavy nuclei are approximated by using Q_{α} values of measured decay chains. Five decay chains were analyzed, which start at the isotopes 285Fl, 294118, 291Lv, 292Lv and 293Lv. The data are compared with predictions of macroscopic-microscopic models. Fission barriers are estimated that can be used to eliminate uncertainties in partial fission half-lives and in calculations of evaporation-residue cross-sections. In that calculations, fission probability of the compound nucleus is a major factor contributing to the total cross-section. The data also provide constraints on the cross-sections of capture and quasi-fission in the entrance channel of the fusion reaction. Arguments are presented that fusion reactions for synthesis of isotopes of elements 118 and 120 may have higher cross-sections than assumed so far.
Calculation of waste disposal rating for the fusion experimental breeder FEB-E
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Using the neutron transport code BISON 3.0, activation calculation code FDKR and its associated data libraries, the activation calculation and analyses of all long-lived radionuclides are performed for the Fusion Experimental Breeder FEB-E. The results indicate that the first wall and blanket structure materials of the FEB-E can meet the nuclear waste disposal criteria for the NRC 10CFR61 Class C after a few weeks from shutdown. The inventory of important actinides during field reprocessing, such as 232U and 237Np, are also calculated. Their concentrations do not excess the limit value required for environmental safety
Energy Technology Data Exchange (ETDEWEB)
Garner, F.A.; Greenwood, L.R. [Pacific Northwest National Lab., Richland, WA (United States); Oliver, B.M.
1996-10-01
For many years it has been accepted that significant differences exist in the helium/dpa ratios produced in fast reactors and various proposed fusion energy devices. In general, the differences arise from the much larger rate of (n,{alpha}) threshold reactions occurring in fusion devices, reactions which occur for energies {ge} 6 MeV. It now appears, however, that for nickel-containing alloys in fast reactors the difference may not have been as large as was originally anticipated. In stainless steels that have a very long incubation period for swelling, for instance, the average helium concentration over the duration of the transient regime have been demonstrated in an earlier paper to be much larger in the FFTF out-of-core regions than first calculated. The helium/dpa ratios in some experiments conducted near the core edge or just outside of the FFTF core actually increase strongly throughout the irradiation, as {sup 59}Ni slowly forms by transmutation of {sup 58}Ni. This highly exothermic {sup 59}Ni(n,{alpha}) reaction occurs in all fast reactors, but is stronger in the softer spectra of oxide-fueled cores such as FFTF and weaker in the harder spectra of metal-fueled cores such as EBR-II. The formation of {sup 59}Ni also increases strongly in out-of-core unfueled regions where the reactor spectra softens with distance from the core.
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Analyses of the prismatic VHTR with Monte Carlo method suffer from slow fission source convergence. MHTGR-350 is a prismatic VHTR, which has an asymmetric reflector thickness along the axial direction. In this case, fission source distribution also becomes strong asymmetrical distribution according to the asymmetric reactor reflector thickness. Therefore, the converged fission source must be verified to pursue the Monte Carlo simulation of the reactor type. In this study, how the axial reflector thickness affects the fission source convergence was evaluated with changing the prismatic VHTR reflector thickness. In this study, how the axial reflector thickness affects the fission source convergence was evaluated. For the symmetric reflector cases, the results show the fission source distribution was converged within 60th cycle. However, in the cases of the asymmetric reflector thickness, it is notified that the convergence cycle of the fission source distribution exceeded 200th cycle. Analysis shows that the inactive cycle for the Monte Carlo eigenvalue calculation should be considerably decided when the reactor has asymmetric reflector thicknesses such as the MHTGR-350. It is expected that these results can be directly used for evaluating and analyzing the prismatic VHTR with Monte Carlo method
Directory of Open Access Journals (Sweden)
A Parvazian
2010-12-01
Full Text Available Fast ignition is a new method for inertial confinement fusion (ICF in which the compression and ignition steps are separated. In the first stage, fuel is compressed by laser or ion beams. In the second phase, relativistic electrons are generated by pettawat laser in the fuel. Also, in the second phase 5-35 MeV protons can be generated in the fuel. Electrons or protons can penetrate in to the ultra-dense fuel and deposit their energy in the fuel . More recently, cylindrical rather than spherical fuel chambers with magnetic control in the plasma domain have been also considered. This is called magnetized target fusion (MTF. Magnetic field has effects on relativistic electrons energy deposition rate in fuel. In this work, fast ignition method in cylindrical fuel chambers is investigated and transportation of the relativistic electrons and protons is calculated using MCNPX and FLUKA codes with 0. 25 and 0. 5 tesla magnetic field in single and dual hot spot. Furthermore, the transfer rate of relativistic electrons and high energy protons to the fuel and fusion gain are calculated. The results show that the presence of external magnetic field guarantees higher fusion gain, and relativistic electrons are much more appropriate objects for ignition. MTF in dual hot spot can be considered as an appropriate substitution for the current ICF techniques.
Winterberg, Friedwardt
2009-01-01
The recently proposed Super Marx generator pure deuterium micro-detonation ignition concept is compared to the Lawrence Livermore National Ignition Facility (NIF) Laser DT fusion-fission hybrid concept (LiFE) [1]. In a Super Marx generator a large number of ordinary Marx generators charge up a much larger second stage ultra-high voltage Marx generator, from which for the ignition of a pure deuterium micro-explosion an intense GeV ion beam can be extracted. A typical example of the LiFE concep...
International Nuclear Information System (INIS)
The kerma heat production density, tritum production density, and dose in a lithium-fluoride pile with a deuterium-tritum neutron source were calculated with a data processing code, UFO, from the pulse height distribution of a miniature NE213 neutron spectrometer, and compared with the values calculated with a Monte Carlo code, MORSE-CV. Both the UFO and MORSE-CV values agreed with the statistical error (less than 6%) of the MORSE-CV calculations, except for the outer-most point in the pile. The MORSE-CV values were slightly smaller than the UFO values for almost all cases, and this tendency increased with increasing distance from the neutron source
International Nuclear Information System (INIS)
The computer program, TRANCS, has been developed for evaluating the fractional release of long-lived fission products from coated fuel particles. This code numerically gives the non-stationary solution of the diffusion equation with birth and decay terms. The birth term deals with the fissile material in the fuel kernel, the contamination in the coating layers and the fission-recoil transfer from the kernel into the buffer layer; and the decay term deals with effective decay not only due to beta decay but also due to neutron capture, if appropriate input data are given. The code calculates the concentration profile, the release to birth rates (R/B), and the release and residual fractions in the coated fuel particle. Results obtained numerically have been in good agreement with the corresponding analytical solutions after the Booth model. Thus, the validity of the present code was confirmed, and further undate of the code has been discussed for extention of its computation scopes and models. (author)
Washiyama Kouhei
2015-01-01
Fusion hindrance, where fusion probability in heavy systems is strongly hindered compared with that in light and medium-mass systems, is analyzed by the microscopic time-dependent energy density functional theory. From trajectories obtained for fusion reactions, we extract nucleus-nucleus potential and one-body energy dissipation for the entrance channel of fusion reactions in heavy systems. We find that a barrier structure disappears and an increase behavior is observed in the obtained poten...
International Nuclear Information System (INIS)
The delayed fission-gamma-ray, which is emitted aggregatively from the unstable nuclides produced by fission, must be taken into account properly in calculation of the gamma-ray source in nuclear reactors. Despite its importance, the delayed gamma-ray data is not well organized nor prepared even in major nuclear data libraries such as JENDL and ENDF/B. Here we prepare the delayed gamma-ray spectra for five major fissioning nuclides. In calculating these spectra, theoretical estimation of the unknown spectra was carried out widely for a lot of no-data nuclides, which had been a major source of ambiguity in calculating the delayed gamma-ray spectra. (author)
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This report contains the texts of the invited presentations (20) delivered at the third Research Co-ordination Meeting of the Co-ordinated Research Programme on Methods for the Calculation of Neutron Nuclear Data for Structural Materials of Fast and Fusion Reactors. The meeting was held at the IAEA Headquarters, Vienna, Austria, from 20 to 22 June 1990. A separate abstract was prepared for each of these presentations. Refs, figs and tabs
Calculation of remote maintenance rating for the fusion experimental breeder FEB
International Nuclear Information System (INIS)
The Remote Maintenance Ratings, RMR, of the first wall and blanket at different time after one full power year operation are calculated for the Fusion Experimental Breeder design using the codes BISON, FDKR and DOSE. The results indicate that based on the present design, an additional 25 cm lead layer is needed to meet the requirement of hand-on maintenance at the outer surface of the magnet shielding, according to the NRC 10CFR20 code
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Half-life values of spontaneous nuclear decay processes are presented in the framework of the Effective Liquid Drop Model (ELDM) using the combination of varying mass asymmetry shape description for the mass transfer with Werner-Wheeler's inertia coefficient VMAS/WW. The calculated half-lives of ground-state to ground-state transitions for the proton emission, alpha decay, cluster radioactivity, and cold fission processes are compared with experimental data. Results have shown that the ELDM is a very efficient model to describe these different decay processes in a same, unified theoretical framework. A Table listing the predicted half-life values, τc is presented for all possible cases of spontaneous nuclear break-up such that -7.30 10 τc [S] 10(τ/τc) > -17.0, where τ is the total half-life of the parent nucleus. (author)
International Nuclear Information System (INIS)
Critical mass experiments were performed using assemblies which simulated one-dimensional lattice consisting of shielding containers with metal fissile materials. Calculations of the criticality of the above assemblies were carried out using the KLAN program with the BAS neutron constants. Errors in the calculations of the criticality for one-, two-, and three-dimensional lattices are estimated. 3 refs.; 1 tab
Study of plasma equilibrium in toroidal fusion devices using mesh-free numerical calculation method
Rasouli, C.; Abbasi Davani, F.; Rokrok, B.
2016-08-01
Plasma confinement using external magnetic field is one of the successful ways leading to the controlled nuclear fusion. Development and validation of the solution process for plasma equilibrium in the experimental toroidal fusion devices is the main subject of this work. Solution of the nonlinear 2D stationary problem as posed by the Grad-Shafranov equation gives quantitative information about plasma equilibrium inside the vacuum chamber of hot fusion devices. This study suggests solving plasma equilibrium equation which is essential in toroidal nuclear fusion devices, using a mesh-free method in a condition that the plasma boundary is unknown. The Grad-Shafranov equation has been solved numerically by the point interpolation collocation mesh-free method. Important features of this approach include truly mesh free, simple mathematical relationships between points and acceptable precision in comparison with the parametric results. The calculation process has been done by using the regular and irregular nodal distribution and support domains with different points. The relative error between numerical and analytical solution is discussed for several test examples such as small size Damavand tokamak, ITER-like equilibrium, NSTX-like equilibrium, and typical Spheromak.
International Nuclear Information System (INIS)
Full text: Tc-99m (decay product of Mo-99) accounts for ∼ 90% of world's production of radiopharmaceuticals. Recent unexpected shutdowns of two fission reactors and routine maintenance closures .e created a global shortage of Tc-99m, hence the large global effort to find alternative sources. This project aims to design and produce a novel prototype Mo-99/Tc-99m source. An operational desktop neutron source is available at the University of Sydney, employing a deuterium fusion-plasma to create 2.45 MeV neutrons. These neutrons will be used to activate Mo-98 thin an activation vessel. In one embodiment, the activation vessel contains an aqueous slurry or gel containing Mo-98 which converts to 0-99 upon activation. The decay product Tc-99m could then be milked, similar to existing Tc-99m generators. Monte Carlo will be :ed to assess yield versus size and geometry for various vessel designs. The neutron source filled with deuterium operating at 250 W, produces 3 x 106 neutrons continuously. The neutron flux can be increased ∼ 100-fold if the fill gas is 50% tritium and by another ∼ 100-1000-fold by increasing the power. This is being designed for local use, perhaps on the scale f one or a few hospitals, so the yield would not need to be industrial ;ale as with fission reactor sources. This device is low cost <$300 K) compared with cyclotrons and fission reactors.
International Nuclear Information System (INIS)
We have measured γ rays in coincidence with 12C fragments from the fission of 56Ni produced with the 32S+24Mg reaction at Elab=140 MeV. These data provide insight into the fission process in this light system by giving information about the energy and spin sharing between the 12C and 44Ti fragments, and the spin alignment of the lighter, 12C fragment. The spin transfer and the nuclear ''temperature'' at scission deduced from this measurement can be related to the compound-nucleus spin and potential energy at scission. The results indicate a statistical decay process consistent with the predictions of the transition-state model employing newer estimates of the spin- and mass-asymmetry-dependent saddle-point energies and corresponding shapes. No evidence is found for the spin alignment of the 12C fragments, contrary to what might be expected for a deep-inelastic scattering origin of the fully energy damped yields
Energy Technology Data Exchange (ETDEWEB)
Powers, Jeffrey James [Univ. of California, Berkeley, CA (United States)
2011-11-30
This study focused on creating a new tristructural isotropic (TRISO) coated particle fuel performance model and demonstrating the integration of this model into an existing system of neutronics and heat transfer codes, creating a user-friendly option for including fuel performance analysis within system design optimization and system-level trade-off studies. The end product enables both a deeper understanding and better overall system performance of nuclear energy systems limited or greatly impacted by TRISO fuel performance. A thorium-fueled hybrid fusion-fission Laser Inertial Fusion Energy (LIFE) blanket design was used for illustrating the application of this new capability and demonstrated both the importance of integrating fuel performance calculations into mainstream design studies and the impact that this new integrated analysis had on system-level design decisions. A new TRISO fuel performance model named TRIUNE was developed and verified and validated during this work with a novel methodology established for simulating the actual lifetime of a TRISO particle during repeated passes through a pebble bed. In addition, integrated self-consistent calculations were performed for neutronics depletion analysis, heat transfer calculations, and then fuel performance modeling for a full parametric study that encompassed over 80 different design options that went through all three phases of analysis. Lastly, side studies were performed that included a comparison of thorium and depleted uranium (DU) LIFE blankets as well as some uncertainty quantification work to help guide future experimental work by assessing what material properties in TRISO fuel performance modeling are most in need of improvement. A recommended thorium-fueled hybrid LIFE engine design was identified with an initial fuel load of 20MT of thorium, 15% TRISO packing within the graphite fuel pebbles, and a 20cm neutron multiplier layer with beryllium pebbles in flibe molten salt coolant. It operated
International Nuclear Information System (INIS)
A preliminary comparative assessment relevant to the transmutation efficiency of plutonium and minor actinides has been performed in the case of ANSALDO's Energy Amplifier Demonstration Facility based on molten lead-bismuth eutectic cooling, classical MOX-fuel technology and operating at 80 MWth. The neutronic calculations presented in this paper are a result of a state-of-the-art computer code package, EA-MC, developed by C. Rubbia and his group at CERN. Both high-energy particle interactions and low-energy neutron transport are treated with a sophisticated method based on a full Monte Carlo simulation, together with modern nuclear data libraries. Detailed Monte Carlo transport calculations were performed for different types of external neutron sources: D-D and D-T fusion sources and proton induced spallation neutron sources. The fuel core was described on a pin-by- pin basis allowing for detailed scans of the main neutronic properties, e.g. neutron flux spectra and power density distributions. (author)
Transmutation of Tc-99 and I-129 in fission reactors. A calculational study
International Nuclear Information System (INIS)
The HWR is a better candidate for large-scale transmutation of long-lived fission products. When target pins containing either Tc-99 or I-129 are positioned in the centre of each fuel bundle of a 935 MWe CANDU reactor, the transmutation half lives are 44 and 20 years, respectively, and the gross transmutation rates 60 and 48 kg/a. The positive coolant void coefficient is reduced in both cases with about 30%. When Tc-99 target pins are positioned in the moderator between the fuel bundles, the transmutation half life becomes 25 years and the gross transmutation rate 106 kg/a. This means that one HWR can serve four PWRs with equal power. The fast reactor seems most promising. When Tc-99 target pins are irradiated in moderated subassemblies in the inner core of Superphenix (∼1240 MWe), a transmutation half life of 15 years is obtained with a gross transmutation rate of 122 kg/a. These values become 18 years and 101 kg/a when non-moderated subassemblies are used for the irradiation. This implies that one fast reactor can serve four to five PWRs with equal power. The PWR seems not very effective for transmutation of Tc-99. Large inventories are needed to obtain a Tc-99 transmutation rate equal to the production rate (18 kg/a for a 900 MWe PWR). When all guide tubes of an UO2 fuelled PWR are filled with Tc-99 with density of 5 g cm-3, the transmutation half life is 39 years and the gross transmutation rate 64 kg/a. (orig./GL)
International Nuclear Information System (INIS)
Intense neutron fluxes within fusion reactors that are currently being designed will lead to the activation of structural components, and to assess and minimize this radioactivity, nuclear cross sections are needed for neutrons with energies up to 20 MeV. We describe research performed for the International Atomic Energy Agency (IAEA) Coordinated Research Programme on activation cross sections for fusion reactor technology, which has selected certain high-priority reactions for both experimental and theoretical study. Using statistical model codes, we have investigated excitation function cross sections for radionuclide production in the reactions 94Mo(n,p)94Nb, 109Ag(n,2n)108mAg, 151Eu(n,2n)150m Eu, 153Eu(n,2n)152g+m2Eu, 159Tb(n,2n)158Tb, 187Re(n,2n)186mRe, 179Hf(n,2n)178m2Hf, 193Ir(n,2n)192m2Ir. Using our calculated results for the excitation functions, along with calculations by other groups, the theoretical excitation functions have been normalized to experimental values at 14.5 MeV to produce evaluated excitation functions. These evaluations can be used within radiation transport and nuclide inventory codes to design, and assess the environmental impact of, fusion reactors. 23 refs., 4 figs., 1 tab
Nuclear model calculations of activation cross sections for fusion reactor technology
International Nuclear Information System (INIS)
Intense neutron fluxes within fusion reactors that are currently being designed will lead to the activation of structural components. To assess and minimize this radioactivity, nuclear cross sections are needed for neutrons with energies up to 20 MeV. We describe research performed for the International Atomic Energy Agency (IAEA) Coordinated Research Programme on activation cross sections for fusion reactor technology, which has selected certain high-priority reactions for both experimental and theoretical study. Using statistical model codes, we have investigated: (1) excitation function cross sections for radionuclide production in the reactions 94Mo(n,p)94Nb, 109Ag(n,2n)108mAg, 151Eu(n,2n)150mEu, 153Eu(n,2n)152g+m2Eu, 159Tb(n,2n)158Tb, 187Re(n,2n)186mRe, 179Hf(n,2n)178m2Hf, 193Ir(n,2n)192m2Ir; and (2) the systematical dependence of isomeric ratios on isomer spin and incident-energy. Using our calculated results for the excitation functions, along with calculations by other groups, the theoretical excitation functions have been normalized to experimental values at 14.5 MeV to produce evaluated excitation functions. These evaluations can be used within radiation transport and nuclide inventory codes to design and assess the environmental impact of fusion reactors. (orig.)
Thermal fission rates with temperature dependent fission barriers
Zhu, Yi
2016-01-01
\\item[Background] The fission processes of thermal excited nuclei are conventionally studied by statistical models which rely on inputs of phenomenological level densities and potential barriers. Therefore the microscopic descriptions of spontaneous fission and induced fission are very desirable for a unified understanding of various fission processes. \\item[Purpose] We propose to study the fission rates, at both low and high temperatures, with microscopically calculated temperature-dependent fission barriers and mass parameters. \\item[Methods] The fission barriers are calculated by the finite-temperature Skyrme-Hartree-Fock+BCS method. The mass parameters are calculated by the temperature-dependent cranking approximation. The thermal fission rates can be obtained by the imaginary free energy approach at all temperatures, in which fission barriers are naturally temperature dependent. The fission at low temperatures can be described mainly as a barrier-tunneling process. While the fission at high temperatures ...
Thermal fission rates with temperature dependent fission barriers
Zhu, Yi; Pei, Junchen
2016-01-01
The fission processes of thermal excited nuclei are conventionally studied by statistical models which rely on inputs of phenomenological level densities and potential barriers. Therefore the microscopic descriptions of spontaneous fission and induced fission are very desirable for a unified understanding of various fission processes. We propose to study the fission rates, at both low and high temperatures, with microscopically calculated temperature-dependent fission barriers and collective ...
International Nuclear Information System (INIS)
A new concept of a Liquid Lithium Fusion Reactor and the first experimental results were presented at the 16th IAEA Conference on Fusion Energy. During the past two years theoretical estimations have been made, and calculated and experimental results have been obtained in confirmation of this concept and supporting its progress. The main results of this work are given in the paper. (author)
Calculation of fission product behavior in a multiple reactor barriers in case of an accident
International Nuclear Information System (INIS)
Radiation protection of the population in case of a reactor accident utilizes reference levels which are based on doses values. Therefore, adequate provisions for effective and timely dose assessment for population in case of accidents at nuclear power plant (NPP) are important. Developing the background for such provisions is the objective of this study. In particular, an exponential model has been developed and utilized to calculate the release rate of the most volatile gaseous materials from different reactor barriers. Calculation has been performed for noble gases (133Xe, 135Xe, 138Xe, 85Kr, 87Kr, 88Kr) and the halogens(1'31I, 132I, 133I, 1'34I, 135I). The effective dose rate equivalent is calculations in the nearly stage of a reactor accident. Calculations are performed using the MCNP-4C code. The results are comparable with the final analysis report which utilizes different codes. Results of our calculation shows no excessive dose in populated regions and it is recommended to use secondary containment barrier for highly reduction of the release rate to the environment. (Author)
Indian Academy of Sciences (India)
M Balasubramaniam; K R Vijayaraghavan; C Karthikraj
2015-09-01
We present the ternary fission of 252Cf and 236U within a three-cluster model as well as in a level density approach. The competition between collinear and equatorial geometry is studied by calculating the ternary fragmentation potential as a function of the angle between the lines joining the stationary middle fragment and the two end fragments. The obtained results for the 16O accompanying ternary fission indicate that collinear configuration is preferred to equatorial configuration. Further, for all the possible third fragments, the potential energy surface (PES) is calculated corresponding to an arrangement in which the heaviest and the lightest fragments are considered at the end in a collinear configuration. The PES reveals several possible ternary modes including true ternary modes where the three fragments are of similar size. The complete mass distributions of Si and Ca which accompanied ternary fission of 236U is studied within a level density picture. The obtained results favour several possible ternary combinations.
Mahaffey, James A
2012-01-01
As energy problems of the world grow, work toward fusion power continues at a greater pace than ever before. The topic of fusion is one that is often met with the most recognition and interest in the nuclear power arena. Written in clear and jargon-free prose, Fusion explores the big bang of creation to the blackout death of worn-out stars. A brief history of fusion research, beginning with the first tentative theories in the early 20th century, is also discussed, as well as the race for fusion power. This brand-new, full-color resource examines the various programs currently being funded or p
International Nuclear Information System (INIS)
The computer codes FRESCO-I, FRESCO-II, PANAMA and SPATRA developed at Forschungszentrum Jülich in Germany in the early 1980s are essential tools to predict the fission product release from spherical fuel elements and the TRISO fuel performance, respectively, under given normal or accidental conditions. These codes are able to calculate a conservative estimation of the source term, i.e. quantity and duration of radionuclide release. Recently, these codes have been reversed engineered, modernized (FORTRAN 95/2003) and combined to form a consistent code named STACY (Source Term Analysis Code System). STACY will later become a module of the V/HTR Code Package (HCP). In addition, further improvements have been implemented to enable more detailed calculations. For example the distinct temperature profile along the pebble radius is now taken into account and coated particle failure rates can be calculated under normal operating conditions. In addition, the absolute fission product release of an V/HTR pebble bed core can be calculated by using the newly developed burnup code Topological Nuclide Transformation (TNT) replacing the former rudimentary approach. As a new functionality, spatially resolved fission product release calculations for normal operating conditions as well as accident conditions can be performed. In case of a full-core calculation, a large number of individual pebbles which follow a random path through the reactor core can be simulated. The history of the individual pebble is recorded, too. Main input data such as spatially resolved neutron fluxes and fluid dynamics data are provided by the VSOP code. Capabilities of the FRESCO-I and SPATRA code which allow for the simulation of the redistribution of fission products within the primary circuit and the deposition of fission products on graphitic and metallic surfaces are also available in STACY. In this paper, details of the STACY model and first results for its application to the 200 MW(th) HTR
Energy Technology Data Exchange (ETDEWEB)
Xhonneux, Andre, E-mail: a.xhonneux@fz-juelich.de [Forschungszentrum Jülich, 52425 Jülich (Germany); Institute for Reactor Safety and Reactor Technology RWTH-Aachen, 52064 Aachen (Germany); Allelein, Hans-Josef [Forschungszentrum Jülich, 52425 Jülich (Germany); Institute for Reactor Safety and Reactor Technology RWTH-Aachen, 52064 Aachen (Germany)
2014-05-01
The computer codes FRESCO-I, FRESCO-II, PANAMA and SPATRA developed at Forschungszentrum Jülich in Germany in the early 1980s are essential tools to predict the fission product release from spherical fuel elements and the TRISO fuel performance, respectively, under given normal or accidental conditions. These codes are able to calculate a conservative estimation of the source term, i.e. quantity and duration of radionuclide release. Recently, these codes have been reversed engineered, modernized (FORTRAN 95/2003) and combined to form a consistent code named STACY (Source Term Analysis Code System). STACY will later become a module of the V/HTR Code Package (HCP). In addition, further improvements have been implemented to enable more detailed calculations. For example the distinct temperature profile along the pebble radius is now taken into account and coated particle failure rates can be calculated under normal operating conditions. In addition, the absolute fission product release of an V/HTR pebble bed core can be calculated by using the newly developed burnup code Topological Nuclide Transformation (TNT) replacing the former rudimentary approach. As a new functionality, spatially resolved fission product release calculations for normal operating conditions as well as accident conditions can be performed. In case of a full-core calculation, a large number of individual pebbles which follow a random path through the reactor core can be simulated. The history of the individual pebble is recorded, too. Main input data such as spatially resolved neutron fluxes and fluid dynamics data are provided by the VSOP code. Capabilities of the FRESCO-I and SPATRA code which allow for the simulation of the redistribution of fission products within the primary circuit and the deposition of fission products on graphitic and metallic surfaces are also available in STACY. In this paper, details of the STACY model and first results for its application to the 200 MW(th) HTR
International Nuclear Information System (INIS)
RETAIN-S is a code for calculating fission product transport in a multicompartment system. The fission products can occur in the form of aerosols and vapours, and revaporization due to surface heating is taken into consideration. The aerosol model uses log-normal approximation for size distribution. The differences between RETAIN-S and the Industry Degraded Core Rulemaking (IDCOR) version of RETAIN are mentioned briefly. The method for calculating condensation of vapours and vaporization due to heating is described. The results of test calculations made on the Surry AB sequence defined by the Group of Experts on the Source Term (GREST) are given and compared with corresponding NAUA results. It is concluded that the degree of agreement is strongly dependent on the model used for gravitational agglomeration efficiency. The calculations made on a Marviken-V experiment are also reported. It is shown that the results are dependent on the possible condensation of fission product vapour on the walls and on aerosols. In addition, the results are given for a BWR meltdown sequence characterized by a large loss-of-coolant accident with loss of all AC power. One important conclusion is that the source term after containment break is mainly determined by the possible re-evaporation of fission products. (author)
Directory of Open Access Journals (Sweden)
Minato Futoshi
2016-01-01
Full Text Available Nuclear β-decay and delayed neutron (DN emission is important for the r-process nucleosynthesis after the freeze-out, and stable and safe operation of nuclear reactors. Even though radioactive beam facilities have enabled us to measure β-decay and branching ratio of neutron-rich nuclei apart from the stability line in the nuclear chart, there are still a lot of nuclei which one cannot investigate experimentally. In particular, information on DN is rather scarce than that of T1/2. To predict T1/2 and the branching ratios of DN for next JENDL decay data, we have developed a method which comprises the quasiparticle-random-phase-approximation (QRPA and the Hauser-Feshbach statistical model (HFSM. In this work, we calculate fission fragments with T1/2 ≤ 50 sec. We obtain the rms deviation from experimental half-life of 3:71. Although the result is still worse than GT2 which has been adopted in JENDL decay data, DN spectra are newly calculated. We also discuss further subjects to be done in future for improving the present approach and making next generation of JENDL decay data.
Minato, Futoshi
2016-06-01
Nuclear β-decay and delayed neutron (DN) emission is important for the r-process nucleosynthesis after the freeze-out, and stable and safe operation of nuclear reactors. Even though radioactive beam facilities have enabled us to measure β-decay and branching ratio of neutron-rich nuclei apart from the stability line in the nuclear chart, there are still a lot of nuclei which one cannot investigate experimentally. In particular, information on DN is rather scarce than that of T1/2. To predict T1/2 and the branching ratios of DN for next JENDL decay data, we have developed a method which comprises the quasiparticle-random-phase-approximation (QRPA) and the Hauser-Feshbach statistical model (HFSM). In this work, we calculate fission fragments with T1/2 ≤ 50 sec. We obtain the rms deviation from experimental half-life of 3:71. Although the result is still worse than GT2 which has been adopted in JENDL decay data, DN spectra are newly calculated. We also discuss further subjects to be done in future for improving the present approach and making next generation of JENDL decay data.
International Nuclear Information System (INIS)
Integral experiments that measure the transport of approx. 14 MeV D-T neutrons through laminated slabs of proposed fusion reactor shield materials have been carried out. Measured and calculated neutron and gamma ray energy spectra are compared as a function of the thickness and composition of stainless steel type 304, borated polyethylene, and Hevimet (a tungsten alloy), and as a function of detector position behind these materials. The measured data were obtained using a NE-213 liquid scintillator using pulse-shape discrimination methods to resolve neutron and gamma ray pulse height data and spectral unfolding methods to convert these data to energy spectra. The calculated data were obtained using two-dimensional discrete ordinates radiation transport methods in a complex calculational network that takes into account the energy-angle dependence of the D-T neutrons and the nonphysical anomalies of the S/sub n/ method
Calculations of alpha particle loss for reversed magnetic shear in the Tokamak Fusion Test Reactor
Energy Technology Data Exchange (ETDEWEB)
Redi, M.H.; White, R.B.; Batha, S.H.; Levinton, F.M.; McCune, D.C.
1997-03-01
Hamiltonian coordinate, guiding center code calculations of the toroidal field ripple loss of alpha particles from a reversed shear plasma predict both total alpha losses and ripple diffusion losses to be greater than those from a comparable non-reversed magnetic shear plasma in the Tokamak Fusion Test Reactor (TFTR) [Fusion Technol. 21, 1324 (1992)]. High central q is found to increase alpha ripple losses as well as first orbit losses of alphas in the reversed shear simulations. A simple ripple loss model, benchmarked against the guiding center code, is found to work satisfactorily in transport analysis modelling of reversed and monotonic shear scenarios. Alpha ripple transport on TFTR affects ions within r/a=0.5, not at the plasma edge. The entire plasma is above threshold for stochastic ripple loss of alpha particles at birth energy in the reversed shear case simulated, so that all trapped 3.5 MeV alphas are lost stochastically or through prompt losses. The 40% alpha particle loss predictions for TFTR suggest that reduction of toroidal field ripple will be a critical issue in the design of a reversed shear fusion reactor.
International Nuclear Information System (INIS)
INDRA is a program system for calculating the neutronics and photonics characteristics of fusion reactor blankets. It incorporates a total of 19 different codes and 5 large data libraries. 10 of the codes are available from the code distribution organizations. Some of them, however, have been slightly modified in order to permit a convenient transfer of information from one program module to the next. The remaining 9 programs have been prepared by the authors to complete the system with respect to flexibility and to facilitate the handling of the results. (orig./WBU)
Present status of coupled-channels calculations for heavy-ion subbarrier fusion reactions
Hagino, K.; Yao, J. M.
2016-05-01
The coupled-channels method has been a standard tool in analyzing heavy-ion fusion reactions at energies around the Coulomb barrier. We investigate three simplifications usually adopted in the coupledchannels calculations. These are i) the exclusion of non-collective excitations, ii) the assumption of coordinate independent coupling strengths, and iii) the harmonic oscillator approximation for multiphonon excitations. In connection to the last point, we propose a novel microscopic method based on the beyond-mean-field approach in order to take into account the anharmonic effects of collective vibrations.
Present status of coupled-channels calculations for heavy-ion subbarrier fusion reactions
Hagino, K
2015-01-01
The coupled-channels method has been a standard tool in analyzing heavy-ion fusion reactions at energies around the Coulomb barrier. We investigate three simplifications usually adopted in the coupled-channels calculations. These are i) the exclusion of non-collective excitations, ii) the assumption of coordinate independent coupling strengths, and iii) the harmonic oscillator approximation for multi-phonon excitations. In connection to the last point, we propose a novel microscopic method based on the beyond-mean-field approach in order to take into account the anharmonic effects of collective vibrations.
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The paper specifies an unambiguous basic relationship between the published results of ab initio calculations of lattice energies,EL,and heats of sublimation,ΔHs,of individual energetic materials. In this relationship,the ΔHs value has been replaced by heats of fusion,ΔHm,tr. Thereby its unambiguity has been lost,and the similarity of details of molecular structure begins to be of decisive importance. The resulting partial relationships,together with the basic relationship,have been used for prediction of ΔHs,and ΔHm,tr values of technically attractive polynitro compounds.
Kendl, Alexander
2014-01-01
Turbulent transport of trace impurities impurities in the edge and scrape-off-layer of tokamak fusion plasmas is modelled by three dimensional electromagnetic gyrofluid computations including evolution of plasma profile gradients. The source function of impurity ions is dynamically computed from pre-determined measured and calculated electron impact ionization cross section data. The simulations describe the generation and further passive turbulent E-cross-B advection of the impurities by intermittent fluctuations and coherent filamentary structures (blobs) across the scrape-off-layer.
International Nuclear Information System (INIS)
The recently proposed super-Marx generator pure deuterium microdetonation ignition concept is compared to the Lawrence Livermore National Ignition Facility (NIF) Laser deuterium-tritium fusion-fission hybrid concept (LIFE). In a super-Marx generator, a large number of ordinary Marx generators charge up a much larger second stage ultrahigh voltage Marx generator from which for the ignition of a pure deuterium microexplosion an intense GeV ion beam can be extracted. Typical examples of the LIFE concept are a fusion gain of 30 and a fission gain of 10, making up a total gain of 300, with about ten times more energy released into fission as compared to fusion. This means the substantial release of fission products, as in fissionless pure fission reactors. In the super-Marx approach for the ignition of pure deuterium microdetonation, a gain of the same magnitude can, in theory, be reached. If feasible, the super-Marx generator deuterium ignition approach would make lasers obsolete as a means for the ignition of thermonuclear microexplosions
International Nuclear Information System (INIS)
During the course of the Mirror Hybrid Fusion-Fission Reactor study several alternate concepts were considered for various reactor components. Several of the alternate concepts do appear to exhibit features with potential advantage for use in the mirror hybrid reactor. These are described and should possibly be investigated further in the future
Energy Technology Data Exchange (ETDEWEB)
Kuijper, J.C.
1992-01-01
The aim of the authors' work was to investigate the static and dynamic properties of a GCFR with oscillating (moving) fuel gas. A simplified schematic diagram of such a GCFR, similar to the concept of Kistemaker (Kis78a), is shown. It consists of a graphite cylinder of, say, 2 m diameter and 10 m length, filled with a mixture of uranium and carbon fluorides (UCF) at high temperature in ionized state, in chemical and thermodynamical equilibrium with the graphite cylinder wall (Kis78a, Kis86, Kle87). The cylindrical gas space is divided into an active 'core' region, surrounded by an effective (thick) neutron reflector, and a so-called 'expander' region, surrounded by a much less effective (thinner or with neutron poison) neutron reflector. In operation, part of the fuel gas oscillates back and forth between core and expander region. The investigation requires the study of neutron statics, neutron kinetics, reactor gas thermodynamics and gas dynamics, resulting in a combined calculational model, containing these aspects. In order to achieve this the authors followed a step-by-step approach.
SPARC-90: A code for calculating fission product capture in suppression pools
International Nuclear Information System (INIS)
This report describes the technical bases and use of two updated versions of a computer code initially developed to serve as a tool for calculating aerosol particle retention in boiling water reactor (BWR) pressure suppression pools during severe accidents, SPARC-87 and SPARC-90. The most recent version is SPARC-90. The initial or prototype version (Owczarski, Postma, and Schreck 1985) was improved to include the following: rigorous treatment of local particle deposition velocities on the surface of oblate spherical bubbles, new correlations for hydrodynamic behavior of bubble swarms, models for aerosol particle growth, both mechanistic and empirical models for vent exit region scrubbing, specific models for hydrodynamics of bubble breakup at various vent types, and models for capture of vapor iodine species. A complete user's guide is provided for SPARC-90 (along with SPARC-87). A code description, code operating instructions, partial code listing, examples of the use of SPARC-90, and summaries of experimental data comparison studies also support the use of SPARC-90. 29 refs., 4 figs., 11 tabs
Decay heat experiment and validation of calculation code systems for fusion reactor
International Nuclear Information System (INIS)
Although accurate estimation of decay heat value is essential for safety analyses of fusion reactors against loss of coolant accidents and so on, no experimental work has been devoted to validating the estimation. Hence, a decay heat measurement experiment was performed as a task (T-339) of ITER/EDA. A new detector, the Whole Energy Absorption Spectrometer (WEAS), was developed for accurate and efficient measurements of decay heat. Decay heat produced in the thirty-two sample materials which were irradiated by 14-MeV neutrons at FNS/JAERI were measured with WEAS for a wide cooling time period from 1 min to 400 days. The data presently obtained were the first experimental decay heat data in the field of fusion. Validity of decay heat calculation codes of ACT4 and CINAC-V4, activation cross section libraries of FENDL/A-2.0 and JENDL Activation File, and decay data was investigated through analyses of the experiment. As a result, several points that should be modified were found in the codes and data. After solving the problems, it was demonstrated that decay heat valued calculated for most of samples were in good agreement with the experimental data. Especially for stainless steel 316 and copper, which were important materials for ITER, decay heat could be predicted with accuracy of ±10%. (author)
Decay heat experiment and validation of calculation code systems for fusion reactor
Energy Technology Data Exchange (ETDEWEB)
Maekawa, Fujio; Ikeda, Yujiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Wada, Masayuki
1999-10-01
Although accurate estimation of decay heat value is essential for safety analyses of fusion reactors against loss of coolant accidents and so on, no experimental work has been devoted to validating the estimation. Hence, a decay heat measurement experiment was performed as a task (T-339) of ITER/EDA. A new detector, the Whole Energy Absorption Spectrometer (WEAS), was developed for accurate and efficient measurements of decay heat. Decay heat produced in the thirty-two sample materials which were irradiated by 14-MeV neutrons at FNS/JAERI were measured with WEAS for a wide cooling time period from 1 min to 400 days. The data presently obtained were the first experimental decay heat data in the field of fusion. Validity of decay heat calculation codes of ACT4 and CINAC-V4, activation cross section libraries of FENDL/A-2.0 and JENDL Activation File, and decay data was investigated through analyses of the experiment. As a result, several points that should be modified were found in the codes and data. After solving the problems, it was demonstrated that decay heat valued calculated for most of samples were in good agreement with the experimental data. Especially for stainless steel 316 and copper, which were important materials for ITER, decay heat could be predicted with accuracy of {+-}10%. (author)
DPA calculation for the D-D nuclear fusion reaction in the KSTAR PFC
International Nuclear Information System (INIS)
The interactions of fusion reaction products such as 2.45-MeV and 14.06-MeV neutrons and 3.05-MeV protons with the KSTAR PFC (plasma facing component) are analyzed using Monte Carlo codes. The dpa (displacement per atom) values in the three-layered PFC of graphite, Cu, and SS316L are calculated, and the depth profile was analyzed for different-type secondary particles. The PHITS code was used for this study. The deposited energy was also calculated for analysis of the nuclear heating effect. The serious irradiation condition of the International Thermonuclear Experimental Reactor (ITER) parameter, a neutron flux of 3.5 x 1013 neutrons/cm2·sec, was applied. The dpa values during one year operation were estimated as 0.75 dpa for graphite, 4.57 dpa for Cu, and 2.69 dpa for SS316L.
Improved Frequency Fluctuation Model for Spectral Line Shape Calculations in Fusion Plasmas
Ferri, S.; Calisti, A.; Mossé, C.; Talin, B.; Lisitsa, V.
2010-10-01
A very fast method to calculate spectral line shapes emitted by plasmas accounting for charge particle dynamics and effects of an external magnetic field is proposed. This method relies on a new formulation of the Frequency Fluctuation Model (FFM), which yields to an expression of the dynamic line profile as a functional of the static distribution function of frequencies. This highly efficient formalism, not limited to hydrogen-like systems, allows to calculate pure Stark and Stark-Zeeman line shapes for a wide range of density, temperature and magnetic field values, which is of importance in plasma physics and astrophysics. Various applications of this method are presented for conditions related to fusion plasmas.
Shielding calculations for the Tokamak Fusion Test Reactor neutral beam injectors
International Nuclear Information System (INIS)
Two-dimensional discrete-ordinates calculations have been performed to determine the location and thickness of concrete shielding around the Tokamak Fusion Test Reactor neutral beam injectors. Two sets of calculations were performed, one to determine the dose equivalent rate on the roof and wall of the test cell building when no injectors are present, and one to determine the contribution to the dose equivalent rate at these locations from radiation streaming through the injection duct. Shielding the side and rear of the neutral beam injector with 0.305 and 0.61 m of concrete, respectively, and lining the inside of the test cell wall with an additional layer of concrete having a thickness of 0.305 m and a height above the axis of deuteron injection of 3.10 m is sufficient to maintain the biological dose equivalent rate outside the test cell to approx. 1 mrem/D-T pulse
International Nuclear Information System (INIS)
Cryotransfer transmission electron microscopy (TEM) experiments have been performed at about 110 K for Ag and Au irradiated with fission neutrons at 6 K and fusion neutrons at 20 K. More than 50% of the observed defect clusters were of interstitial type. The average size of defect clusters increased as neutron dose became higher. This result was explained by the effect of freely migrating interstitial atoms produced by newly developed displacement cascades. The effect of the difference in neutron spectrum was manifested in the number of defect clusters in a group of closely existing clusters ('subcascade' structure). There was a possibility that interstitial-type defect clusters were nucleated in the close vicinity of subcascades. ((orig.))
Nouicer, Rachid
1997-01-01
Le travail de cette thése a montré d'une part le rôle significatif du mécanisme de \\underline{Fusion-Fission Asymétrique} dans les collisions entre ions lourds légers (A$_{\\rm NC} \\le$60) et, d'autre part, le \\underline{Désalignement des Spins} dans un systéme {\\it oblate-oblate} mettant en évidence pour \\underline{la premiére fois le {\\it mode papillon} lors de la réaction dans les résonances quasi-moléculaires}. Ces deux aspects, l'un macroscopique l'autre beaucoup plus lié á des effets mic...
Energy Technology Data Exchange (ETDEWEB)
Duarte, S.B.; Tavares, O.A.P.; Guzman, F.; Dimarco, A. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Garcia, F. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica; Universidade Estadual de Santa Cruz, Ilheus, BA (Brazil). Dept. de Ciencias Exatas e Tecnologicas; Rodriguez, O. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica; Instituto Superior de Ciencias e Tecnologia Nucleares, La Habana (Cuba); Goncalves, M. [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil)
2002-01-01
Half-life values of spontaneous nuclear decay processes are presented in the framework of the Effective Liquid Drop Model (ELDM) using the combination of varying mass asymmetry shape description for the mass transfer with Werner-Wheeler's inertia coefficient V{sub MAS}/WW. The calculated half-lives of ground-state to ground-state transitions for the proton emission, alpha decay, cluster radioactivity, and cold fission processes are compared with experimental data. Results have shown that the ELDM is a very efficient model to describe these different decay processes in a same, unified theoretical framework. A Table listing the predicted half-life values, {tau}{sub c} is presented for all possible cases of spontaneous nuclear break-up such that -7.30 <{approx_equal} log{sub 10} {tau}{sub c} [S] <{approx_equal} 27.50 and log {sub 10}({tau}/{tau}{sub c}) > -17.0, where {tau} is the total half-life of the parent nucleus. (author)
International Nuclear Information System (INIS)
A method for calculating the fraction of the rare gas fission products that diffuses out of a UO2 fuel element under conditions In a reactor is outlined, The method is based on the values of the diffusion constant found in laboratory experiments, as described In CRDC-718, and assumes that these remain unaltered during the period that the fuel is in the reactor, The method has been applied to two types of oxide in the X-2-f loop test of 1956 and the results compared with the amounts of fission gas found by analysis of the gases collected in sheath puncture experiments, as described in CRDC-719. The calculated values depend heavily on the estimated temperatures In the fuel. They are in close agreement with the experimental values provided that, in calculating the temperature, certain assumptions are made regarding the thermal expansion of the oxide cylinder. (author)
International Nuclear Information System (INIS)
Mass yields from fission induced by a span of neutron energies up to 18 MeV have been measured for Th232, U235 and U238 target nuclei. Particular attention has been given to the dependence of symmetric fission yields on energy. To study the effect of angular momentum, fission yields from the U236 compound nucleus formed by alpha-particle irradiations of Th232 were also studied over the same span of excitation energies. A standard set of Pd109, Ag111, Pd112 and Ag113 symmetric fission yields was generally measured for all irradiations. In addition, yields of Eu156, Cs136 and 2.3-d Cd115 were measured for some selected combinations of projectile, energy and target nucleus. Assays for Zr97 and sometimes also Ba139 served as fission monitors. Altogether 150 fission yields were measured for these combinations of target nucleus, projectile and incident energy. About one-third of these were checked by replicated irradiations. At highest energies for the U236 compound nucleus the symmetric fission yield from alpha-particle-induced fission is about 13% higher than for neutron-induced fission. Dips in symmetric fission yield were observed at the energy onset of third-chance fission for each target and projectile. Some indication of a small central peak in the mass distribution was observed in the yields from U236 compound nucleus fission, but not from the Th233 compound nucleus fission. Detailed mathematical methods have been developed to separate the effects of fissions preceding and following neutron emission. These methods were used to remove the effects of second- and third-chance fissions from the measured symmetric fission yields. These calculated yields for first-chance fission show no dips with energy. The calculations also show that perhaps half the difference between symmetric yields for alpha- particle-induced fission of Th232 and neutron-induced fission of U235 is attributable to angular momentum effects. Both calculated first-chance yields and measured yields
International Nuclear Information System (INIS)
Radiotoxicity is one of important characteristics of radwaste hazard. Radiotoxicity of actinides and fission products from spent fuel of VVER-1000 reactor for processes of burnup, long-term storage, and transmutation is discussed. (author)
International Nuclear Information System (INIS)
Sensitivity of principal neutronics characteristic quantities for the neutron cross sections of JAERI Experimental Fusion Reactor (JXFR) has been studied by means of sensitivity analysis method based on linear perturbation theory. The same study was made previously. After publication of the previous results, however, the SWANLAKE code used to calculate sensitivities was found to include error derived during its conversion process. The study was thus repeated with corrected SWANLAKE. The quantities studied are calculational results for the first preliminary design of JXFR such as the (n, p) reaction rates of 58Ni and 54Fe in the outer part of superconducting toroidal field coil (TFC), the copper atomic displacement rate in the inner part of TFC and the tritium production rate in the outer blanket. Though the calculational results do not contradict essentially the results in the former study, the newly calculated sensivitities were found to be more or less different from the previous ones. Therefore, the results and discussion of analysis given in this report are revised, with the values corrected. The errors of the (n, p) reaction rates and the copper displacement rate due to the uncertainties of cross sections were estimated to be about 50 - 70% and 25 - 65%, respectively, taking into account the direct sensitivity of (n, p) reaction cross sections in the former. (author)
International Nuclear Information System (INIS)
Time distributions of muon-catalyzed fusion events in deuterium are calculated in the temperature range T=35 - 1000 K using the recent predictions for the μCF parameters. The kinetic graph taken into consideration includes spin structure of dμ and ddμ together with the corresponding hyperfine and back decay transitions. Comparison of the calculated curves with the experimental data at T=35 K and 300 K is presented. In general, the data suggest the resonant rates which are smaller than recently calculated. An attempt is made to fit the data using the resonance and back decay rates rescaled by a common factor. The fits show that the rates should be reduced at least by a factor of about three. However, this assumption is not sufficient for a consistent description of the time distributions at both temperatures and more data are needed to resolve the existing ambiguity. The corresponding curves are calculated also for other temperatures. 29 refs., 6 figs. (author)
Dissipative dynamics in quasi-fission
Oberacker, V E; Simenel, C
2014-01-01
Quasi-fission is the primary reaction mechanism that prevents the formation of superheavy elements in heavy-ion fusion experiments. Employing the time-dependent density functional theory approach we study quasi-fission in the systems $^{40,48}$Ca+$^{238}$U. Results show that for $^{48}$Ca projectiles the quasi-fission is substantially reduced in comparison to the $^{40}$Ca case. This partly explains the success of superheavy element formation with $^{48}$Ca beams. For the first time, we also calculate the repartition of excitation energies of the two fragments in a dynamic microscopic theory. The system is found in quasi-thermal equilibrium only for reactions with $^{40}$Ca. The differences between both systems are interpreted in terms of initial neutron to proton asymmetry of the colliding partners.
In-beam fission study for Heavy Element Synthesis
Directory of Open Access Journals (Sweden)
Nishio Katsuhisa
2013-12-01
Full Text Available Fission fragment mass distributions were measured in heavy-ion induced fissions using 238U target nucleus. The measured mass distributions changed drastically with incident energy. The results are explained by a change of the ratio between fusion and qasifission with nuclear orientation. A calculation based on a fluctuation dissipation model reproduced the mass distributions and their incident energy dependence. Fusion probability was determined in the analysis. Evaporation residue cross sections were calculated with a statistical model in the reactions of 30Si + 238U and 34S + 238U using the obtained fusion probability in the entrance channel. The results agree with the measured cross sections for seaborgium and hassium isotopes.
International conference on fifty years research in nuclear fission
International Nuclear Information System (INIS)
These proceedings contain extended abstracts of the papers presented at the named conference. They deal with static properties of fission, instrumentation for fission studies, fission in compound-nucleus reactions, fission dynamics, fission-like heavy ion reactions, and fusion reactions. See hints under the relevant topics. (HSI)
International Nuclear Information System (INIS)
To improve the accuracy of the neutron analyses for subcritical systems with thermal fission blanket, a coupled neutron and photon (315 n + 42γ) fine-group cross section library HENDL3.0/FG based on ENDF/B-Ⅶ. 0 has been produced by FDS team. In order to test the availability and reliability of the HENDL3.0/FG data library, shielding and critical safety benchmarks were performed with VisualBUS code. The testing results indicated that the discrepancy between calculation and experimental values of nuclear parameters fell in a reasonable range. (authors)
International Nuclear Information System (INIS)
Two calculationally efficient methods have been developed to compute the induced radioactivity due to pulsed/intermittent irradiation histories as encountered in both magnetic and inertial fusion energy devices. The numerical algorithms are based on the linear chain method (Bateman Equations) and employ series reduction and matrix algebra. The first method models the case in which the irradiated materials are present throughout a series of irradiation pulses. The second method treats the case where a fixed amount of radioactive and transmuted material is created during each pulse. Analytical solutions are given for each method for a three nuclide linear chain. Numerical results and comparisons are presented for a select number of linear chains. (orig.)
Parameter-free effective field theory calculation for the solar proton-fusion and hep processes
Energy Technology Data Exchange (ETDEWEB)
T.S. Park; L.E. Marcucci; R. Schiavilla; M. Viviani; A. Kievsky; S. Rosati; K. Kubodera; D.P. Min; M. Rho
2002-08-01
Spurred by the recent complete determination of the weak currents in two-nucleon systems up to {Omicron}(Q{sup 3}) in heavy-baryon chiral perturbation theory, we carry out a parameter-free calculation of the threshold S-factors for the solar pp (proton-fusion) and hep processes in an effective field theory that combines the merits of the standard nuclear physics method and systematic chiral expansion. The power of the EFT adopted here is that one can correlate in a unified formalism the weak-current matrix elements of two-, three- and four-nucleon systems. Using the tritium {beta}-decay rate as an input to fix the only unknown parameter in the theory, we can evaluate the threshold S factors with drastically improved precision; the results are S{sub pp}(0) = 3.94 x (1 {+-} 0.004) x 10{sup -25} MeV-b and S{sub hep}(0) = (8.6 {+-} 1.3) x 10{sup -20} keV-b. The dependence of the calculated S-factors on the momentum cutoff parameter {Lambda} has been examined for a physically reasonable range of {Lambda}. This dependence is found to be extremely small for the pp process, and to be within acceptable levels for the hep process, substantiating the consistency of our calculational scheme.
International Nuclear Information System (INIS)
In the field of tritium and fusion blanket technology possibly an important and early contribution to the development of a fusion reactor blanket can be obtained by irradiation experiments at the research reactor FRJ-2 in Juelich, Federal Republic of Germany. However, the tritium production rate of 0.2 x 1013 to 2 x 1013 cm-3s-1 and the power per volume of 2 to 20 W cm-3 characteristic for a fusion reactor blanket have to be realized. The present report shows the reachable tritium values calculated for different irradiation positions in the FRJ-2 for natural lithium as a breeder material considering the actual existing neutron spectrum. Based on these results we come to the conclusion that the specified blanket data can actually be reached and adjusted. Therefore irradiation experiments at the FRJ-2 would be able to supply basical results for the fusion blanket development. (orig.)
Analysis of Cold Leg LBLOCA for Fusion-fission Hybrid Reactor%聚变-裂变混合堆冷管段大破口失水事故分析
Institute of Scientific and Technical Information of China (English)
喻章程; 解衡
2014-01-01
将非能动堆芯冷却系统（PXS）应用于聚变-裂变混合堆，使用RELAP5对混合堆一回路、部分二回路和PXS进行了建模，对冷管段双端剪切断裂大破口失水事故进行了瞬态计算和分析研究。计算结果显示：破口发生后出现两次燃料温度峰值，均发生在外包层，第1次峰值温度发生在约11 s ，为938.2 K ；第2次峰值温度发生在约50 s ，为608.7 K。两次燃料温度峰值均低于燃料U-10Zr的熔点，在可接受范围内。随着瞬态过程的深入，安注箱、堆芯补水箱及安全壳内储水箱的冷却水开始注入包层，使内外包层的坍塌液位开始回升，最终重新淹没堆芯。表明PXS在冷管段双端剪切断裂大破口失水事故下能保证混合堆堆芯的安全，将其应用于聚变-裂变混合堆是可行的。%The passive core cooling system (PXS) was applied to fusion-fission hybrid reactor and a RELAP5 model was developed to represent the primary loop , partial secondary loop and the PXS components .The transient calculation and analysis were conducted for the double ended rupture LBLOCA on cold leg .The results show that two peak fuel temperatures appear in the outer blanket during the transient duration after the break happens .The first peak fuel temperature is 938.2 K at about 11 s and the second is 608.7 K at about 50 s ,but both are below the melting point of U-10Zr and within the acceptable range .With the transient process developing ,the coolant in ACC , CM T and IWST was injected to the blanket and the collapsed liquid level in the blanket started to rise ,and finally the reactor core was covered by injected coolant again .The results indicate that the PXS can ensure the safety of fusion-fission hybrid reactor in the double ended rupture LBLOCA on cold leg and it is feasible to apply the PXS to fusion-fission hybrid reactor .
聚变-裂变混合堆冷管段大破口失水事故分析%Analysis of Cold Leg LBLOCA for Fusion-fission Hybrid Reactor
Institute of Scientific and Technical Information of China (English)
喻章程; 解衡
2014-01-01
将非能动堆芯冷却系统（PXS）应用于聚变-裂变混合堆，使用RELAP5对混合堆一回路、部分二回路和PXS进行了建模，对冷管段双端剪切断裂大破口失水事故进行了瞬态计算和分析研究。计算结果显示：破口发生后出现两次燃料温度峰值，均发生在外包层，第1次峰值温度发生在约11 s ，为938.2 K ；第2次峰值温度发生在约50 s ，为608.7 K。两次燃料温度峰值均低于燃料U-10Zr的熔点，在可接受范围内。随着瞬态过程的深入，安注箱、堆芯补水箱及安全壳内储水箱的冷却水开始注入包层，使内外包层的坍塌液位开始回升，最终重新淹没堆芯。表明PXS在冷管段双端剪切断裂大破口失水事故下能保证混合堆堆芯的安全，将其应用于聚变-裂变混合堆是可行的。%The passive core cooling system (PXS) was applied to fusion-fission hybrid reactor and a RELAP5 model was developed to represent the primary loop , partial secondary loop and the PXS components .The transient calculation and analysis were conducted for the double ended rupture LBLOCA on cold leg .The results show that two peak fuel temperatures appear in the outer blanket during the transient duration after the break happens .The first peak fuel temperature is 938.2 K at about 11 s and the second is 608.7 K at about 50 s ,but both are below the melting point of U-10Zr and within the acceptable range .With the transient process developing ,the coolant in ACC , CM T and IWST was injected to the blanket and the collapsed liquid level in the blanket started to rise ,and finally the reactor core was covered by injected coolant again .The results indicate that the PXS can ensure the safety of fusion-fission hybrid reactor in the double ended rupture LBLOCA on cold leg and it is feasible to apply the PXS to fusion-fission hybrid reactor .
Neutronic and thermal calculation of blanket for high power operating condition of fusion reactor
International Nuclear Information System (INIS)
Internal (breeding region) structures of ceramic breeder blanket to accommodate high power operating conditions such as a DEMO reactor have been investigated. The conditions considered here are the maximum neutron wall load of 2.8 MW/m2 at outboard midplane corresponding to a fusion power of 3.0 GW and the coolant temperature of 200 degrees C. Structure of a blanket is based on the layered pebble bed concept, which has been proposed by Japan since the ITER CDA. Lithium oxide with 50% enriched 6Li is used in a shape of small spherical pebbles which are filled in a 316SS can avoid its compatibility issue with Be. Beryllium around the breeder can is filled also in a shape of spherical pebbles which works not only as a neutron multiplier but also as a thermal resistant layer to maintain breeder temperature for effective in-situ tritium recovery. Diameters and packing fractions of both pebbles are ≤ 1 mm and 65%, respectively. A layer of block Be between cooling panels is introduced as a neutron multiplier (not as the thermal resistant layer) to enhance tritium breeding performance. Inlet temperature of water coolant is 200 degrees C to meet the high temperature conditioning requirement to the first wall which is one of walls of the blanket vessel. Neutronics calculations have been carried out by one-dimensional transport code, and thermal calculations have also been carried out by one-dimensional slab code
Institute of Scientific and Technical Information of China (English)
陈德鸿; 杜红飞; 蒋洁琼; 汪晖; 王福琼; 陈一平; 吴宜灿; FDS团队
2012-01-01
Based on the recent experiment progress of Gas Dynamic Trap (GDT), a core plasma physics conceptual design for driving fission blanket was proposed The 0-D physical model was built and the core plasma parameters with 50 MW fusion power were preliminarily designed The reliability of the physical model and design was demonstrated by comparison between the calculation and the experiment results.%基于Gas Dynamic Trap(GDT)装置的实验进展,提出了用于驱动聚变裂变混合堆包层的聚变堆芯参数设计.基于零维堆芯物理模型,计算分析给出了一套聚变功率为50 MW的初步堆芯参数方案.利用GDT装置的实验结果对该物理模型进行计算对比校验,显示该物理模型和设计参数的可靠性.
International Nuclear Information System (INIS)
Experimental studies of fast fission phenomena are presented. The paper is divided into three parts. In the first part, problems associated with fast fission processes are examined in terms of interaction potentials and a dynamic model is presented in which highly elastic collisions, the formation of compound nuclei and fast fission appear naturally. In the second part, a description is given of the experimental methods employed, the observations made and the preliminary interpretation of measurements suggesting the occurence of fast fission processes. In the third part, our dynamic model is incorporated in a general theory of the dissipative processes studied. This theory enables fluctuations associated with collective variables to be calculated. It is applied to highly inelastic collisions, to fast fission and to the fission dynamics of compound nuclei (for which a schematic representation is given). It is with these calculations that the main results of the second part can be interpreted
Tel, E.; Durgu, C.; Aktı, N. N.; Okuducu, Ş.
2010-06-01
Fusion serves an inexhaustible energy for humankind. Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. Tritium self-sufficiency must be maintained for a commercial power plant. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. So, the working out the systematics of ( n, t) reaction cross sections is of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at different energies. In this study, ( n, t) reactions for some structural fusion materials such as 27Al, 51V, 52Cr, 55Mn, and 56Fe have been investigated. The new calculations on the excitation functions of 27Al( n, t)25Mg, 51V( n, t)49Ti, 52Cr( n, t)50V, 55Mn( n, t)53Cr and 56Fe( n, t)54Mn reactions have been carried out up to 50 MeV incident neutron energy. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the new evaluated the geometry dependent hybrid model, hybrid model and the cascade exciton model. Equilibrium effects are calculated according to the Weisskopf-Ewing model. Also in the present work, we have calculated ( n, t) reaction cross-sections by using new evaluated semi-empirical formulas developed by Tel et al. at 14-15 MeV energy. The calculated results are discussed and compared with the experimental data taken from the literature.
International Nuclear Information System (INIS)
The report contains the texts of the 9 invited papers delivered during the Second Research Co-ordination Meeting on ''Methods for the Calculation of Fast Neutron Nuclear Data for Structural Materials and Fast and Fusion Reactors'' held in Vienna during 15-17 February 1988. A separate abstract was prepared for each of these 9 papers. Refs, figs and tabs