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[en] Calculations of the CABRI REP-Na5 pulse were performed with the ALCYONE code in order to determine the evolution of the thermomechanical loading applied on the cladding tube during the Pellet–Cladding Mechanical Interaction (PCMI) phase of a rapid Reactivity Initiated Accident (RIA) initiated at 280 °C that lasted 8.8 ms. The evolution of the following parameters are reported: the cladding temperature, heating rate, strain rate and loading biaxiality. The impact of these parameters on the cladding mechanical behavior and fracture are then briefly reviewed

[en] An intensity-interrogated fiber magnetic field sensor based on magnetic fluid (MF) and tilted long-period fiber grating (TLPFG) has been proposed. The sensor is constructed by a TLPFG immersed in the MF. The TLPFGs supported the coupling between the LP_0_1 core mode and the forward-propagating cladding modes with different azimuthal order l = 0, 1, 2,…, which shows different spectral response behaviors with normal long-period fiber gratings. The experimental results and theoretical analysis show that resonance wavelengths of TLPFG present different characteristics by tuning the applied magnetic field intensity. The transmission loss of the TLPFG increases for some dips, while they reduce for the others with the increment of the applied magnetic field intensity. Taking advantage of the optical power difference for various wavelength regions, a magnetic field intensity sensitivity of 0.05 dB Oe"−"1 could be achieved for a magnetic intensity range from 75 Oe to 300 Oe. Due to its low cost and compactness, the proposed sensor is expected to find potential applications in the field of magnetic field measurement and photonic devices. (paper)

[en] Leaky mode losses for a range of parameters such as the spacing and size of air holes, as well as the wavelength in W-type multimode glass photonic crystal fiber, are reported. Using an effective index approach by numerical solution of the time-independent power flow equation, we obtained that the leaky mode losses increase as the wavelength increases, and this rise of losses is greater in the case of narrower inner cladding. This user-friendly, simple approach of computing leaky losses could be used by experimentalists and system users. (letter)

[en] The effective index of index-guided photonic crystal fibers (IG-PCFs) is experimentally obtained as a function of the wavelength by writing fiber Bragg gratings (FBG) in the fibers. The results are found to be in good agreement with theoretical simulations and are also discussed and compared with measurements on standard telecommunication fibers. Differences between the fibers were observed both in the Bragg grating inscription process and in the evolution of the fiber effective index value with the wavelength, which depends on the fiber cladding microstructure. Index evolution slopes of −2.029 × 10⁻⁵ nm⁻¹, −2.044 × 10⁻⁵ nm⁻¹ and −1.388 × 10⁻⁵ nm⁻¹ were measured for two IG-PCFs and the standard fiber, respectively

[en] The crucial mechanical property for nuclear fuel cladding survival under reactivity initiated accident (RIA) is the cladding ductility. In this paper, main parameters affecting failure strain of fuel cladding during RIA are discussed, aiming at identifying key parameters for the clad ductility

[en] Pellet-Clad Mechanical Interaction (PCMI) has been known as a potential threat in fuel cladding integrity during power ramp conditions and high burn-up scenario. As the fuel outer surface contact with clad inner surface, the local stress become increased. Moreover, fuel pellet have much higher temperature in operation and have much greater expansion effects than clad, which occur additional contact pressure on clad inner surface, the cladding pellet deforms into a shape reflecting that of the pellet. This mechanical interaction between fuel pellet and clad depends on gap size, burn-up, friction coefficient between clad and pellet. Moreover, recent field result shows that nearly PCI-induced failures are thought to have developed at a missing pellet surface (MPS), where the tangential stress has its maximum and the cladding temperature has its minimum. For the additional study on PCMI, it is very important and valuable to find geometric parameters of MPS which make critical safety issue on cladding material safety. Followings are result and conclusion of the parametric studies

[en] As part of a study of various aspects of oil dispersant application technology, a comparison study was conducted employing the Airborne Dispersant Delivery System (ADDS) pack and the Modular Aerial Spray System (MASS) in C-130 Hercules aircraft at altitudes of 50-150 ft above ground and at speeds up to 200 knots. Dyed Corexit 9527 was applied at a target dose rate of 5 gal/acre over a collection grid composed of metal trays, Kromekote cards, oil-sensitive cards, a continuous trough, and a WRK string collector. Analysis of the collected dispersant was done by colorimetry, fluorometry, and image analysis. Correlations through the different methodologies demonstrated that high speed, moderate altitude application of oil dispersant could be successful in delivering dispersant to the surface at effective concentration and drop size. Environmental studies of the test area showed no residual dispersant in the soil following cessation of spraying. 1 ref

[en] The power of a focused laser beam with a Gaussian intensity profile attenuated by powder in coaxial laser cladding is investigated experimentally and theoretically, and its resolution model is developed. With some assumptions, it is concluded that the attenuation of laser power is an exponential function and is determined by the powder feed rate, particle moving speed, spraying angles and waist positions and diameters of the laser beam and powder flow, grain diameter and run of the laser beam through the powder flow. The attenuation of laser power increases with powder feed rate or run of laser beam through the powder flow. In the experiment presented, 300 W laser power from a focused Gaussian beam is attenuated by a coaxial powder flow. The experimental results agree well with the values calculated with the developed model

[en] The prediction of the microstructure and morphology of thermal sprayed coatings is of great interest to manufacturing engineers for purpose of optimizing the coatings for a particular application. On the whole, the modeling of the thermal spray deposition process may be divided into three separate stages. The phenomena occurring at stage of particles-substrate collision determine the adhesion between particles and substrate and cohesion between sprayed particles, as the crystal structure and crystal sizes, porosity formation and formation of microcracks. The particle-substrate interaction is the basic elementary act of thermal sprayed coating buildup. Therefore, it is very important to develop the principles of system approach to modeling of sprayed particles interaction with substrate in process of thermal spraying of coatings for better understanding of mechanism of thermal spray coating formation and control of their properties. The proposed model have six levels for analysis of particle-substrate interaction system: functional, technological, mechanical interaction, thermal, mass transfer level, and metallophysics level. (author)