TRANSIENT HEAT TRANSFER ANALYSIS UP TO DRYOUT IN 3D FUEL RODS UNDER UNIDEAL CONDITIONS THROUGH THE DEVELOPMENT OF A COMPUTER CODE

In this paper we analyze a conjugated transient heat transfer problem consisting of a nuclear reactor’s fuel rod and its intrinsic coolant channel. Our analysis is made possible through a computer code being developed at the Instituto de Engenharia Nuclear (IEN/CNEN). This code is meant to study the temperature behavior in fuel rods which exhibit deviation from their ideal conditions, that is, rods in which the cladding is deformed or the fuel is dislocated. It is also designed to avoid the use of the computationally expensive Navier-Stokes equations. For these reasons, its physical model has as basis a three-dimensional fuel rod coupled to a one-dimensional coolant channel, which are discretized using the finite element method. Intending to study accidental conditions in which the coolant (light water) transcends its saturation temperature, turning into vapor, a homogeneous mixture is used to represent the two-phase flow, and so the coolant channel’s energy equation is described using enthalpy. Owing to the fact that temperature and enthalpy are used in the physical model, it became impractical to generate a fully coupled method for solving the pertinent equations. Thus, the conjugated heat transfer problem is solved in a segregated manner through the implementation of an iterative method. Finally, as study cases for this paper we present analyses concerning the behavior of the hottest fuel rod in a Pressurized Water Reactor during a shutdown wherein the residual heat removal system is lost (loss of the reactor’s coolant pumps). These studies contemplate cases in which the fuel rod’s geometry is ideal or curved. Analyses are also performed for two circumstances of positioning of the fuel inside the rod: concentric and eccentric.In this paper we analyze a conjugated transient heat transfer problem consisting of a nuclear reactor’s fuel rod and its intrinsic coolant channel. Our analysis is made possible through a computer code being developed at the Instituto de Engenharia Nuclear (IEN/CNEN). This code is meant to study the temperature behavior in fuel rods which exhibit deviation from their ideal conditions, that is, rods in which the cladding is deformed or the fuel is dislocated. It is also designed to avoid the use of the computationally expensive Navier-Stokes equations. For these reasons, its physical model has as basis a three-dimensional fuel rod coupled to a one-dimensional coolant channel, which are discretized using the finite element method. Intending to study accidental conditions in which the coolant (light water) transcends its saturation temperature, turning into vapor, a homogeneous mixture is used to represent the two-phase flow, and so the coolant channel’s energy equation is described using enthalpy. Owing to the fact that temperature and enthalpy are used in the physical model, it became impractical to generate a fully coupled method for solving the pertinent equations. Thus, the conjugated heat transfer problem is solved in a segregated manner through the implementation of an iterative method. Finally, as study cases for this paper we present analyses concerning the behavior of the hottest fuel rod in a Pressurized Water Reactor during a shutdown wherein the residual heat removal system is lost (loss of the reactor’s coolant pumps). These studies contemplate cases in which the fuel rod’s geometry is ideal or curved. Analyses are also performed for two circumstances of positioning of the fuel inside the rod: concentric and eccentric.In this paper we analyze a conjugated transient heat transfer problem consisting of a nuclear reactor’s fuel rod and its intrinsic coolant channel. Our analysis is made possible through a computer code being developed at the Instituto de Engenharia Nuclear (IEN/CNEN). This code is meant to study the temperature behavior in fuel rods which exhibit deviation from their ideal conditions, that is, rods in which the cladding is deformed or the fuel is dislocated. It is also designed to avoid the use of the computationally expensive Navier-Stokes equations. For these reasons, its physical model has as basis a three-dimensional fuel rod coupled to a one-dimensional coolant channel, which are discretized using the finite element method. Intending to study accidental conditions in which the coolant (light water) transcends its saturation temperature, turning into vapor, a homogeneous mixture is used to represent the two-phase flow, and so the coolant channel’s energy equation is described using enthalpy. Owing to the fact that temperature and enthalpy are used in the physical model, it became impractical to generate a fully coupled method for solving the pertinent equations. Thus, the conjugated heat transfer problem is solved in a segregated manner through the implementation of an iterative method. Finally, as study cases for this paper we present analyses concerning the behavior of the hottest fuel rod in a Pressurized Water Reactor during a shutdown wherein the residual heat removal system is lost (loss of the reactor’s coolant pumps). These studies contemplate cases in which the fuel rod’s geometry is ideal or curved. Analyses are also performed for two circumstances of positioning of the fuel inside the rod: concentric and eccentric

Integração espacial de dados para agricultura de precisão na unidade piloto com cana-de-açúcar, Mogi Mirim, SP.

Uma das principais aplicações da agricultura de precisão na cana-de-açúcar é a identificação da variabilidade espacial dos fatores de produção. O objetivo do trabalho foi a integração de informações espaciais de solo e planta para identificação das zonas homogêneas na Unidade Piloto com cana-de-açúcar, Mogi Mirim, SP. Os dados foram coletados na área com cana-de-açúcar na safra 2011/2012 com grade mínima de 90 pontos. Foram coletadas amostras de solo e planta: granulometria (15 cm); densidade do solo (15 e 30 cm); resistência à penetração do solo (0-10, 10-20 e 20-30 cm); número de colmos (colmos m-2); índice de vegetação (NDVI) pelo sensor Crop Circle; condutividade elétrica do solo pelo sensor Veris (30 e 90 cm). De acordo com os resultados houve dependência espacial para a maioria dos atributos do solo e da planta, e a interpolação permitiu visualizar a divisão da área em duas partes, uma ao norte da área e outra ao sul, separadas pela pedreira identificada na imagem de satélite e na imagem do veículo aéreo não tripulado. Também foram identificadas duas regiões distintas quanto ao número de colmos e o índice de vegetação. A condutividade elétrica apresentou dependência espacial de fraca a nula e não foi identificada relação espacial com os demais atributos. Assim, a partir da análise geoestatística, foi possível a identificação de duas zonas homogêneas, o que pode vir a auxiliar na tomada de decisão quanto ao manejo localizado da propriedade agrícola estudada

Postpartum consultation: Occurrence, requirements and expectations

<p>Abstract</p> <p>Background</p> <p>As a matter of routine, midwives in Sweden have spoken with women about their experiences of labour in a so-called 'postpartum consultation'. However, the possibility of offering women this kind of consultation today is reduced due to shortage of both time and resources. The aim of this study was to explore the occurrence, women's requirements of, and experiences of a postpartum consultation, and to identify expectations from women who wanted but did not have a consultation with the midwife assisting during labour.</p> <p>Methods</p> <p>All Swedish speaking women who gave birth to a live born child at a University Hospital in western Sweden were consecutively included for a phone interview over a three-week period. An additional phone interview was conducted with the women who did not have a postpartum consultation, but who wanted to talk with the midwife assisting during labour. Data from the interviews were analysed using qualitative content analysis.</p> <p>Results</p> <p>Of the 150 interviewed women, 56% (n = 84) had a postpartum consultation of which 61.9% (n = 52) had this with the midwife assisting during labour. Twenty of the 28 women who did not have a consultation with anyone still desired to talk with the midwife assisting during labour. Of these, 19 were interviewed. The content the women wanted to talk about was summarized in four categories: to understand the course of events during labour; to put into words, feelings about undignified management; to describe own behaviour and feelings, and to describe own fear.</p> <p>Conclusion</p> <p>The survey shows that the frequency of postpartum consultation is decreasing, that the majority of women who give birth today still require it, but only about half of them receive it. It is crucial to develop a plan for these consultations that meets both the women's needs and the organization within current maternity care.</p