•A new approach compared to solid-fuel reactors for MAs loading was introduced.•The transmutation performance of 241Am and 237Np in the critical SD-TMSR was investigated.•The transmutation ratio was ...calculated using the SERPENT-2 Monte-Carlo code.•The on-line reprocessing and refueling was applied during burnup.
In the current work, we introduce a new approach compared to solid-fuel reactors to load the minor actinides (MAs) into the Single-fluid Double-zone Thorium-based Molten Salt Reactor (SD-TMSR). The proposed approach merges the advantages of both homogeneous and heterogeneous approaches. Among MAs nuclides, 241Am and 237Np are selected for transmutation due to their long half-life. We simulate two separate tanks; Pu + U tank and FPs tank. In this study, a tank is a right cylinder with a volume of 1.0 m3. The Pu + U tank is used to store Pu and U isotopes extracted from the central channel of the SD-TMSR. However, the FPs tank is used to store all fission products (FPs) produced from the transmutation process in the central channel. The overall change in the actinides and FPs mass during the irradiation has been calculated using direct SERPENT-2 calculations. The results show that the transmutation ratio of 241Am and 237Np reaches 98.5% and 93.2%, respectively after 1500 days of irradiation. We notice that the major isotope in the Pu + U tank is 238Pu. Under 241Am irradiation, our proposed approach offers ≈0.3kg of 238Pu after 1 year of operation. However, under 237Np irradiation, 2.5 times more 238Pu can be extracted after the same period of operation. The produced 238Pu can be used in the radioisotope thermoelectric generators (RTG, RITEG) and radioisotope heater units.
Some fundamental ideas and the results of approximation theory based on them are reviewed. The review covers the development of this branch of mathematics from its origins to the end of the 20th ...century.
In high energy experiments such as active beam dump searches for rare decays and missing energy events, the beam purity is a crucial parameter. In this paper we present a technique to reject heavy ...charged particle contamination in the 100 GeV electron beam of the H4 beam line at CERN SPS. The method is based on the detection with BGO scintillators of the synchrotron radiation emitted by the electrons passing through a bending dipole magnet. A 100 GeV π− beam is used to test the method in the NA64 experiment resulting in a suppression factor of 10−5 while the efficiency for electron detection is ∼95%. The spectra and the rejection factors are in very good agreement with the Monte Carlo simulation. The reported suppression factors are significantly better than previously achieved.
In this paper we examined the developed structural models of the road landscape and the road micro-landscape, which allows taking into account all the necessary conditions for road construction in ...local territories. In local areas, the complexity of road construction depends on the general characteristics inherent in a given landscape, of which the micro landscape under consideration is a component. For a comprehensive assessment of the conditions of road construction in local territories, a structural model of the road micro landscape is proposed, which is based on the landscape model. The developed structural models of the road landscape and the road micro-landscape reflect the influence of natural and techno genic factors, the value of land and other factors to determine the complexity of the construction of forest roads. Factors are defined and formulas are presented to take into account the features of the relief, climate, physical and geographical processes and phenomena, surface and groundwater, soil, vegetation, human activities when determining the cost of the construction of a forest road. The structural model of the micro landscape allows a comprehensive assessment of local territories in the survey area, to determine micro landscapes in which the complexity of road construction and the value of the territories will have minimal indicators. A correlation analysis was also carried out, which made it possible to establish the most important characteristics of the components of the geographical environment, which affect the complexity of the construction of a forest road for the main types of costs.
Domain wall mobility as a function of nonmagnetic interlayer thickness and temperature was studied in ultrathin exchange-coupled ferromagnetic layers using magneto-optic Kerr microscopy. The system ...under study is a Pt/Co/Pt/Co/Pt heterostructure having perpendicular magnetic anisotropy and a middle Pt layer with spatially variable thickness. The ferromagnetic interaction between the Co layers is observed when the Pt interlayer thickness varies from 5 to 6 nm in a temperature range of 200–300 K. There is a certain interval of Pt layer thickness where domain walls in both ferromagnetic layers move independently. Nonlinear dependence of the domain wall displacement on the applied field was measured. It is shown that an equilibrium position of the relaxed domain wall depends on field, temperature, and the nonmagnetic interlayer thickness. This position is determined by the energy balance: (i) domain wall displacement provided by the applied field, (ii) interlayer exchange interaction in the area swept by the domain wall, and (iii) domain wall coercivity. The mechanism of domain wall stabilization in terms of independent wall motion near critical thickness was considered. It is found that both the coercivity of the Co layer and the critical thickness decrease at higher temperature, while the interlayer exchange constant J is changed weakly.
•Five initial fissile loadings were studied for transitioning to the thorium fuel cycle•The MSR burnup routine was used to simulate the online reprocessing and refueling.•The dynamics of keff and ...essential safety parameters were investigated in this work.•The neutron energy spectrum shift during the reactor operation was calculated.•Temperature coefficient of reactivity evolution during SD-TMSR operation was investigated.
Liquid-fueled Molten Salt Reactor (MSR) systems represent advances in safety, economics, and sustainability. The MSR has been designed to operate with a Th/233U fuel cycle with 233U used as startup fissile material. Since 233U does not exist in nature, we must examine other available fissile materials to start up these reactor concepts. This work investigates the fuel cycle and neutronics performance of the Single-fluid Double-zone Thorium-based Molten Salt Reactor (SD-TMSR) with different fissile material loadings at startup: High Assay Low Enriched Uranium (HALEU) (19.79%), Pu mixed with HALEU (19.79%), reactor-grade Pu (a mixture of Pu isotopes chemically extracted from Pressurized Water Reactor (PWR) spent nuclear fuel (SNF) with 33 GWd/tHM burnup), transuranic elements (TRU) from Light Water Reactor (LWR) SNF, and 233U. The MSR burnup routine provided by SERPENT-2 is used to simulate the online reprocessing and refueling in the SD-TMSR. The effective multiplication factor, fuel salt composition evolution, and net production of 233U are studied in the present work. Additionally, the neutron spectrum shift during the reactor operation is calculated. The results show that the continuous flow of reactor-grade Pu helps transition to the thorium fuel cycle within a relatively short time (≈4.5 years) compared to 26 years for 233U startup fuel. Finally, using TRU as the initial fuel materials offers the possibility of operating the SD-TMSR for an extended period of time (≈40 years) without any external feed of 233U.
The long-lived minor actinides (MA); americium, neptunium, and curium are main contributors to the long-term radiotoxicity of used fuel. Thus, the transmutation of these MAs is considered as an ...alternative to direct burial. Until now, no unambiguous internationally recognized quantitative criterion for the effectiveness of MA transmutation has been developed, although this would be highly desirable. The absolute and relative decrease in the total mass of MA is completely inadequate, since they ignore the accumulation of higher radiotoxic MA from the transmuted nuclide. In this paper, we propose a new criterion for the efficiency of MA transmutation in nuclear reactors and demonstrate its efficiency when comparing two molten salt reactors; Single-fluid Double-zone Thorium-based Molten Salt Reactor (SD-TMSR) and Small Molten Salt Fast Reactor (SMSFR). In addition, the proposed criterion takes into account the mass of all useful MA, short-lived MA, and short-lived fission products (FPs). We present a new approach to loading MA in SD-TMSR and SMSFR. The total change in the mass of actinides and FPs during irradiation was calculated using SERPENT-2 Monte Carlo code. The results show that the transmutation efficiency of
241
Am (a major candidate for transmutation) in SD-TMSR is much higher than in SMSFR. After 1500 days of irradiation, the transmutation efficiency reaches 82.6% for SD-TMSR, but for SMSFR it reaches 52.5%.
Status report on silicon photomultiplier development and its applications Dolgoshein, B.; Balagura, V.; Buzhan, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2006, Letnik:
563, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The state of art of the Silicon Photomultipliers (SiPM's)—their features, possibilities and applications—is given. The significant progress of this novel technique of photo detection is described and ...discussed.
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