Core safety of Indian nuclear power plants (NPPs) under extreme conditions

Nuclear power is currently the fourth largest source of electricity production in India after thermal, hydro and renewable sources of electricity. Currently, India has 20 nuclear reactors in operation and seven other reactors are under construction. Most of these reactors are indigenously designed and built Heavy Water Reactors. In addition, a 300 MWe Advanced Heavy Water Reactor has already been designed and in the process of deployment in near future for demonstration of power production from Thorium apart from enhanced safety features by passive means. India has ambitious plans to enhance the share of electricity production from nuclear. The recent Fukushima accident has raised concerns of safety of Nuclear Power Plants worldwide. The Fukushima accident was caused by extreme events, i.e., large earthquake followed by gigantic Tsunami which are not expected to hit India’s coast considering the geography of India and historical records. Nevertheless, systematic investigations have been conducted by nuclear scientists in India to evaluate the safety of the current Nuclear Power Plants in case of occurrence of such extreme events in any nuclear site. This paper gives a brief outline of the safety features of Indian Heavy Water Reactors for prevention and mitigation of such extreme events. The probabilistic safety analysis revealed that the risk from Indian Heavy Water Reactors are negligibly small.     

HEAT TRANSFER IN MULTIPHASE CONTACTORS

A procedure for the prediction of wall-bed heat transfer coefficient for bubble columns and gas-solid fluidized beds is developed on the basis of hydrodynamic behavior of these contactors. A comparison between the predicted and experimental values of heat transfer coefficient over a wide range of design and operating variables is presented. An attempt is made to analyze the occurrence of maxima in heat transfer coefficient with respect to gas velocity in the case of fluidized beds. A procedure for the calculation of the optimum superficial gas velocity is outlined.     

Studies on the skin uptake and efflux kinetics of N-phenyl-p-phenylenediamine: an aromatic amine intermediate

N-phenyl-p-phenylenediamine (N-PPDA), an industrial intermediate and hair dye ingredient, has been implicated in a variety of toxic symptoms including cutaneous manifestations. However, the role of physiological factors that may determine and modify its absorption and transport within and through the skin is not fully understood. The present study reveals that N-PPDA binds readily to skin showing saturation kinetics with K m and V_max of 2.54 × 10⁻⁴ M and 4.76 μmol g⁻¹ skin, respectively. The uptake was dependent upon the area of skin, concentration of the amine, exposure time, temperature and pH of the vehicle. Heat treatment facilitated the binding but temperatures abouv 50° caused significant lowering of the uptake, indicating the possible involvement of collagen matrix. Skin lipids also contributed in the binding of N-PPDA. Bioinhibitors such as KCN, sodium arsenate, NaF, N-ethylmaleimide, cycloheximide, iodoacetic acid and 2,4-dinitrophenol had no effect on the uptake potential, suggesting it to be a non-energy dependent process. Most of the skin-bound N-PPDA was effluxed through serum proteins reaching the target organs via systemic circulation.     

ASCORBYL PALMITATE AS AN ANTIOXIDANT FOR DEEP FAT FRYING OF POTATO CHIPS IN PEANUT OIL

The antioxidative properties of ascorbyl palmitate (AP) alone and in combination with other known antioxidants were investigated during deep fat frying of potato chips in peanut oil. Their effect on the quality of the frying oil and shelf-life of the fried product were studied. The other antioxidants tested were butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and propyl gallate (PG). The characteristics evaluated for the frying oil were color development, viscosity, peroxide value (PV) and polymerization of the oil during deep fat frying; AP was found to reduce these values. It also helped to prevent the degradation of the oil by retaining the unaltered triacylglycerols during the frying period. Addition of AP to the frying oil reduced the PV of the extracted fat, doubled the shelf-life of the fried product and improved the quality of frying oil with increase in frying time. However, AP did not show any synergistic effect with other antioxidants examined.     

Role of iron oxide impurities in electrocatalysis by multiwall carbon nanotubes: An investigation using a novel magnetically modified ITO electrodes

The role of iron oxide impurities in the electrocatalytic properties of multiwall carbon nanotubes (MWCNTs) prepared by catalytic chemical vapour decomposition method (CCVD) is studied in detail. A novel magnetically modified electrodes have been developed by which MWCNTs were immobilized on indium-tin oxide (ITO) electrodes, without any chemical binders. The electro-catalytic oxidation of dopamine, and reduction of hydrogen peroxide have been studied by cyclic voltammetry on magnetically modified electrodes with (i) MWCNTs with occluded iron oxide impurities (Fe-MWCNTs), (ii) MWCNTs grown on iron oxide nanoparticle particulate films (Io-MWCNTs) and (iii) pristine iron oxide nanoparticle particulate film (Io-NPs). A shift towards less positive potentials for the oxidation of dopamine was observed which is in the order of Fe-MWCNTs < Io-MWCNTs < Io-NPs. Similarly, trend towards less negative potentials for the reduction of hydrogen peroxide was observed. Thus, the electrocatalytic activities displayed by MWCNTs have been attributed to the iron oxide impurities associated with it. The systematic variation was related to the nature of interaction of iron oxide nanoparticles with MWCNT surface.     

A response surface approach to developing composite dispatching rules for flexible manufacturing systems

We present a new approach to scheduling Flexible Manufacturing Systems based on Response Surface Modelling methodology. This experimental technique for model building is used to generate scheduling rules which are then used by the machines in the process of job selection. A systematic procedure to identify factors of interest and utilize them to develop a scheduling mechanism is presented. Issues of automation revision of the rules to adapt to changes in the shop are also discussed. The approach was tested as part of a larger framework of distributed decision making for scheduling and was found to perform significantly better than static heuristic procedures.     

Robustness of extended-Kalman-type observers

Robustness properties of extended-Kalman-type observers are investigated for linear plants when actuators and sensors have non-linearities or linear dynamics. Sufficient conditions for the stability of the estimation error are obtained for time-varying extended Kalman filters (EKF) for time-varying plants, and for constant-gain, exponentially weighted EKF for time-invariant plants. When the non-linearities are known only within bands of uncertainty, it is proved that the observer is non-divergent.     

Modeling Rheological Characteristics and Calcium Content of Mozzarella Cheese

ABSTRACT: Correlation and regression analyses of calcium concentration and rheological characteristics in Mozzarella cheese were studied. Part-skim and fat-free Mozzarella cheeses were manufactured on 4 separate occasions. Calcium concentration in both types of cheeses was manipulated at 4 different levels. Rheological characteristics such as melt area, softening, melting, and flow were studied on days 1, 7, 15, and 30. The results revealed that 57%, 52%, 66%, 74%, 67%, and 53% variation, respectively, in melt area, softening temperature, softening time, melting time, flow rate, and extent of flow could be explained as a function of calcium concentration of part-skim Mozzarella cheese. Calcium concentration explained 50%, 61%, and 43% variation, respectively, in melting time, flow rate and extent of flow, but poor correlation existed between calcium concentration and melt area, softening and melting time-temperatures of fat-free Mozzarella cheese. Calcium concentration, among all compositional parameters, was highly correlated with rheological characteristics of Mozzarella cheeses. Calcium concentration was also one of the major predictor variables in regression models, which were developed to decide the rheological characteristics of Mozzarella cheese. Based on the above correlation the cheese industry can develop a strategy to obtain specific characteristics in Mozzarella cheese for varied applications in the food systems.     

A NUMERICAL METHOD OF SIMULATING THE AXISYMMETRICAL FREEZING OF FOOD SYSTEMS

A numerical method is developed to simulate the temperature progression of freezing a food system. It is assumed to have a constant density and to be macroscopically homogeneous during the freezing operation. The simulated results are compared with the measured temperature progression in the center of a beef slab immersed in a-39°F bath.