Experimental investigations of natural circulation in a separate-and-mixed effects test facility mimicking prismatic modular reactor (PMR) core

After the Fukushima Daiichi nuclear power plant accident in 2011, significant attention was directed to investigate natural circulation thermal-hydraulics in Prismatic Modular Reactors (PMRs). Natural circulation is employed as a passive safety feature that passively removes the decay heat released after the loss of flow accidents (LOFA). Several computational studies have addressed such phenomena, however, validation of Computational Fluid Dynamics (CFD) is needed by providing high-quality data obtained from separate test facilities designed with reference to the corresponding reference PMRs. To address this need, a separate effects Plenum-to-Plenum Facility (P2PF) was designed and developed with dual channels and plena for experimental investigations of naturally driven gas thermal and velocity fields under different circulation intensities. Thermal and velocity measurements have been characterized by implementation of advanced sophisticated measurement techniques such as: (1) the hot wire anemometry (HWA), (2) flush-mounted micro-foil sensors, and (3) thermocouples that are capable of providing local measurements at different axial and radials positions along both channels. These measurement techniques have been integrated in a novel way so that the thermocouple readings are not disturbed by the HWA sensor, and vice versa. This proposed work has a significant impact on advancing the knowledge and understanding of the plenum-to-plenum (P2P) natural circulation thermal-hydraulic phenomenon and provides high-quality benchmark data that are much needed for verification and validation (V&V) of computational fluid dynamics (CFD) models and codes. Therefore, computational simulations can be reliably used in designing PMRs passive safety systems and in safety analysis and assessment --Abstract, page iv

Estimation of TNF- α and LDH in Chronic Periodontitis Patients in Mosul

The objective of the study is to estimate salivary concentration of TNF-α and LDH level in chronic periodontitis and control group, and correlate them with periodontal parameters. The study group consisted of 44 patients suffering from chronic periodontitis, aging between ≤16-45 years old and 40 control samples collected from healthy individuals ranged between 16-40 years old .Chronic periodontitis was assessed on the basis of several periodontal parameters, including probing pocket depth (PPD), clinical attachment loss (CAL), bleeding on probing  (BOP) and plaque index (PI). 5ml of unstimulated saliva was collected from patients and control groups to measure salivary biomarkers by ELISA technique. the mean concentrations of TNF-α in the study and control groups were (6.9pg/ml) and (5.6 pg/ml) respectively, data analysis showed no significant difference between the two groups (P< 0.05), and the mean LDH level in chronic periodontitis was (7.7855) and in control group the mean was (0.5555)   and the difference was highly significant )p≤ 0.000). Salivary TNF-α and LDH showed positive correlation with clinical periodontal parameters

Extracting Concrete Thermal Characteristics from Temperature Time History of RC Column Exposed to Standard Fire

A numerical method to identify thermal conductivity from time history of one-dimensional temperature variations in thermal unsteady-state is proposed. The numerical method considers the change of specific heat and thermal conductivity with respect to temperature. Fire test of reinforced concrete (RC) columns was conducted using a standard fire to obtain time history of temperature variations in the column section. A thermal equilibrium model in unsteady-state condition was developed. The thermal conductivity of concrete was then determined by optimizing the numerical solution of the model to meet the observed time history of temperature variations. The determined thermal conductivity with respect to temperature was then verified against standard thermal conductivity measurements of concrete bricks. It is concluded that the proposed method can be used to conservatively estimate thermal conductivity of concrete for design purpose. Finally, the thermal radiation properties of concrete for the RC column were estimated from the thermal equilibrium at the surface of the column. The radiant heat transfer ratio of concrete representing absorptivity to emissivity ratio of concrete during fire was evaluated and is suggested as a concrete criterion that can be used in fire safety assessment

Development, Validation And Implementation Of Multiple Radioactive Particle Tracking Technique

Computer Automated Radioactive Particle Tracking (CARPT) technique has been successfully utilized to measure the velocity profiles and mixing parameters in different multiphase flow systems where a single radioactive tracer is used to track the tagged phase. However, many industrial processes use a wide range of particles with different physical properties where solid particles could vary in size, shape and density. For application in such systems, the capability of current single tracer CARPT can be advanced to track more than one particle simultaneously. Tracking multiple particles will thus enable to track the motion of particles of different size shape and density, determine segregation of particles and probing particle interactions. In this work, a newly developed Multiple Radioactive Particle Tracking technique (M-RPT) used to track two different radioactive tracers is demonstrated. The M-RPT electronics was developed that can differentiate between gamma counts obtained from the different radioactive tracers on the basis of their gamma energy peak. The M-RPT technique was validated by tracking two stationary and moving particles (Sc-46 and Co-60) simultaneously. Finally, M-RPT was successfully implemented to track two phases, solid and liquid, simultaneously in three phase slurry bubble column reactors

New recursive approximations for variable-order fractional operators with applications

To broaden the range of applicability of variable-order fractional differential models, reliable numerical approaches are needed to solve the model equation.In this paper, we develop Laguerre spectral collocation methods for solving variable-order fractional initial value problems on the half line. Specifically, we derive three-term recurrence relations to efficiently calculate the variable-order fractional integrals and derivatives of the modified generalized Laguerre polynomials, which lead to the corresponding fractional differentiation matrices that will be used to construct the collocation methods. Comparison with other existing methods shows the superior accuracy of the proposed spectral collocation methods

Preliminary hydraulic fracturing campaign strategies for unconventional and tight reservoirs of UAE: Case studies and lessons learned

The challenges associated with applying hydraulic fracturing (HF) technology to tight carbonate reservoirs with very low clay content are substantial and demand a unique cost optimization strategy, especially in the context of low oil prices. This study discusses the challenges of applying HF technology to such reservoirs in the UAE. The work presents a comprehensive approach to assess and employ this technology, including a thorough study, a strategic roadmap, screening procedures, a fracturing workflow and strategy and an examination of the distinctive challenges and lessons learned from the process. The primary goal is to formulate a strategy that is applicable to tight and unconventional formations in the UAE, with a strong emphasis on cost optimization. Also, the evaluation methods of the fracturing technologies for these reservoirs were discussed, such as creating valid geomechanical properties to construct a Mechanical Earth Model (MEM) for successful execution and evaluating the reservoir quality. The results showed that conventional acidizing is not effective in stimulating the tight carbonate reservoirs, whereas acid-fracturing has successfully broken down the formation. It was also found that strategic planning, equipment availability, geomechanical studies and building an effective MEM are necessary for obtaining the optimum fracturing design and achieving successful development

Serum Cytokines Profiles and Some Salivary Parameters in Chronic Periodontitis Patients in Mosul - Iraq

The aim of study is to measure serum IL-1 ?, IL-6, IL-8, IFN-? and TNF-? levels, and some of salivary parameters like sIgA, total protein and peroxidase specific activity in patients with chronic periodontitis in Mosul and compared them with control group. The study population consisted of 91 patients suffering from chronic periodontitis, aging between ?18-73 years old and 18 control samples collected from healthy individuals ranged between 23-35 years old. Blood and saliva samples were collected from patients and control groups to measure serum IL-1?, IL-6, IL-8, IFN-? and TNF-? ,and salivary sIgA , total protein levels and peroxidase specific activity . In the present study most of patients were showed localized chronic periodontitis, ranging from severe 57% to moderate infection 43%.Salivary sIgA level showed significant increase in chronic periodontitis comparing with control group.Patients group showed significance correlation between serum TNF-? with serum IL-1?, IL-6 and IFN-? levels. Also serum IL-1? level showed significant correlation with salivary sIgA and total protein levels. Furthermore negative correlations were detected between salivary sIgA and serum IL-8, as well asbetween salivary total protein and peroxides specific activity. According to periodontal pocket depth, serum IL-1?, IFN-?, salivary sIgA levels and salivary peroxidase specific activity showed significance increase in patients with 7mm pocket depth. In the present study, most of patients showed localized chronic periodontitis. Salivary sIgA level showed significant increase in chronic periodontitis comparing with control group. Serum IL-1?, IFN-?, salivary sIgA levels and salivary peroxidase specific activitywere linked with 7mm periodontal pocket depth

Flexural Strengthening of RC Slabs Using a Hybrid FRP-UHPC System Including Shear Connector

A polymeric hybrid composite system made of UHPC and CFRP was proposed as a retrofit system to enhance flexural strength and ductility of RC slabs. While the effectiveness of the proposed system was confirmed previously through testing three full-scale one-way slabs having two continuous spans, the slabs retrofitted with the hybrid system failed in shear. This sudden shear failure would stem from the excessive enhancement of the flexural strength over the shear strength. In this study, shear connectors were installed between the hybrid system and a RC slab. Using simple beam, only positive moment section was examined. Two full-scale RC slabs were cast and tested to failure: the first as a control and the second using this new strengthening technique. The proposed strengthening system increased the ultimate load carrying capacity of the slab by 70%, the stiffness by 60%, and toughness by 128%. The efficiency of shear connectors on ductile behavior of the retrofitted slab was also confirmed. After the UHPC top is separated from the slab, the shear connector transfer shear load and the slab system were in force equilibrium by compression in UHPC and tension in CFRP