Passive residual energy utilization system in thermal cycles on water-cooled power reactors

This work presents a concept of a residual energy utilization in nuclear plants thermal cycles. After taking notice of the causes of the Fukushima nuclear plant accident, an idea arose to adapt a passive thermal circuit as part of the ECCS (Emergency Core Cooling System). One of the research topics of IEAv (Institute for Advanced Studies), as part of the heat conversion of a space nuclear power system is a passive multi fluid turbine. One of the main characteristics of this device is its passive capability of staying inert and be brought to power at moments notice. During the first experiments and testing of this passive device, it became clear that any small amount of gas flow would generate power. Given that in the first stages of the Fukushima accident and even during the whole event there was plenty availability of steam flow that would be the proper condition to make the proposed system to work. This system starts in case of failure of the ECCS, including loss of site power, loss of diesel generators and loss of the battery power. This system does not requires electricity to run and will work with bleed steam. It will generate enough power to supply the plant safety system avoiding overheating of the reactor core produced by the decay heat. This passive system uses a modified Tesla type turbine. With the tests conducted until now, it is possible to ensure that the operation of this new turbine in a thermal cycle is very satisfactory and it performs as expected

Startup transients in accelerator driven systems using cinesp-ads code

Accelerator Driven Systems (ADS) are subcritical nuclear reactor cores driven by spallation neutron source. These spallation neutrons are provided from the bombardment of a liquid metal flowing in a central region of the core, by a proton beam coming from a linear accelerator. Since neutron source dominates the neutronic of the ADS, its control usually is not related to the delayed neutron fractions as in the critical systems. In this way, ADS kinetics diverges from the former ones. This work presents some results of transients in ADS. Since ADS is to work in a pulsed regime, with time duration of pulse, a parametric result is showed to point out that different pulse durations should be studied in conjunction with pulse intensity, to maintain the ADS power stable. In addition, before generating these results, some transients were used to validate the CINESP-ADS code. It solves numerically the kinetic equations based on the multigroup diffusion theory, in One- or Twodimensional, in the Cartesian or Cylindrical geometries, and for any energy and delayed neutron groups. Threedimensional simulation is possible using a reactor transversal buckling. The numerical solution is obtained via finite differences for the spatial discretization, using the so-called box integration, and with the use of Alternating Direction Explicit (ADE) methods, for the time discretization. The code application to some transients due to source neutron variations demonstrates its efficiency and accuracy, when compared with analytical techniques, such as one that uses expansion in series of Helmholtz eigenfunctions

Actran: a code for depletion calculations in PWR cores aiming the production of minor actinide for using in ads

Despite of the renewed willing to accept nuclear power as a mean of mitigate the climate changing, to deal with the long lived waste still cause some concerning in relation to maintain in safety condition, during so many years. A technological solution to overcome this leg of time is to use a facility that burn these waste, besides to generate electricity. This is the idea built in the accelerator driven systems (ADS). This technology is being though to use some minor actinides (MAs) as fuel. This work presents a program to assess actinide concentrations, aiming a fertile-free fuel to be used in the future ADS technology. For that, use was made of a numerical code to solve the steady-state multigroup diffusion equation 3D to calculate the neutron fluxes, coupled it with a new code to solve, also numerically, depletion equations, named ACTRAN code. This paper shows the simulation of a PWR core during the residence time of the nuclear fuel, for three years, and after, for almost four hundred years, to assess the MAs production. The results show some insight in the best management to get a minimum amount of some MAs to use in the future generations of ADS

Developing strength-endurance for combat sports athletes

[EN] Strength-endurance is one of the trainable physical capacities that could determine the success in some combat sports and its inclusion is obligatory in the training periodization of high-level athletes. In striking combat sports, such as boxing and taekwondo, it seems likely that increases in dynamic strength-endurance improve the ability to execute combat movements repeatedly. On the other hand, grapplers need to develop high levels of strength-endurance because during the match much time is spent in grip dispute and the success in this phase may determine the possibility to execute scoring techniques. Furthermore, in mixed combat sports, where a combination of striking and grappling are required, athletes needs to have the capacity to maintain dynamic or static muscular actions during prolonged periods during the match, and the strength-endurance is one key element. Therefore, this chapter presents the strength-endurance requirements during the match, the specific tests for its evaluation, scientific evidence of longitudinal studies on the development of strength-endurance in combat sports athletes and the methods for its development

Macroscopic multigroup constants for accelerator driven system core calculations

The high-level wastes stored in facilities above ground or shallow repositories, in close connection with its nuclear power plant, can take almost 106 years before the radiotoxity became of the order of the background. While the disposal issue is not urgent from a technical viewpoint, it is recognized that extended storage in the facilities is not acceptable since these ones cannot provide sufficient isolation in the long term and neither is it ethical to leave the waste problem to future generations. A technique to diminish this time is to transmute these long-lived elements into short-lived elements. The approach is to use an Accelerator Driven System (ADS), a sub-critical arrangement which uses a Spallation Neutron Source (SNS), after separation the minor actinides and the long-lived fission products (LLFP), to convert them to short-lived isotopes. As an advanced reactor fuel, still today, there is a few data around these type of core systems. In this paper we generate macroscopic multigroup constants for use in calculations of a typical ADS fuel, take into consideration, the ENDF/BVI data file. Four energy groups are chosen to collapse the data from ENDF/B-VI data file by PREPRO code. A typical MOX fuel cell is used t

Sonority effects in the production of the triconsonantal sequences Ct/d]σC by Brazilian learners of L2 English

This study investigates the production of a variable pattern in English by Brazilian L2 learners, i.e. triconsonantal sequences containing coronal plosives flanked by heterosyllabic consonants. Thus, the interlanguage of 24 learners from the city of Campina Grande in the state of Paraíba, Brazil, is analyzed to achieve the following objectives: (1) verify the phonological processes whereby the sequences Ct/d]σC are simplified in the participants’ interlanguage; and (2) examine the role of sonority in the surface phonetic representations of these sequences. 1,071 tokens were audio-recorded, coded and subjected to multivariate analysis using Rbrul (JOHNSON, 2015). The results indicate that sonority-based principles play an important role in the application of repair strategies on the surface forms of these complex structures

Public Transport by Vans: Facts, Meaning and Perspectives of its Presence in Brazilian Cities

Until five years ago the scene of public transport in Brazilian cities was dominated by privately operated buses under local protective regulation. From 1996 on, however, this scene begun to change by the emergence of vans operators who challenged bus cartels and the barriers to entry imposed by public authorities. In this paper, a general overview of the presence of vans in Brazilian local public transport is provided. Quantitative, regulatory and political facts are presented and analyzed. Furthermore, present trends related to regulatory policies concerning vans are assessed and possible developments regarding its presence in passenger transport markets are discussed

Public Transport by Vans: Facts, Meaning and Perspectives of its Presence in Brazilian Cities

Until five years ago the scene of public transport in Brazilian cities was dominated by privately operated buses under local protective regulation. From 1996 on, however, this scene begun to change by the emergence of vans operators who challenged bus cartels and the barriers to entry imposed by public authorities. In this paper, a general overview of the presence of vans in Brazilian local public transport is provided. Quantitative, regulatory and political facts are presented and analyzed. Furthermore, present trends related to regulatory policies concerning vans are assessed and possible developments regarding its presence in passenger transport markets are discussed