Hybrid I&C Grounding in PFBR

Nuclear Power plants require well established grounding scheme  towards personnel safety and smooth control of the  plant.  Combination of Single & Multi point grounding with Faraday cage configuration is followed in Prototype Fast Breeder Reactor (PFBR).  This paper explains the scheme. Keywords: Ground, Shield, Cage, Safet

Development of FPGA Based System for Neutron Flux Monitoring in Fast Breeder Reactors

The project aims to calculate the frequency of the neutron flux by monitoring the signal from neutron detector from shutdown to full power over 10 decades. This neutron flux signal is input to the FPGA based MODULE. A mathematical relationship has been established between the neutron flux (frequency of the neutrons) and the area under the signal. Variable amplitude and occurrence have been accounted for. White noise has also been added and tested for.  VHDL has been used to simplify the otherwise complicated logic gate design. Mathematical modeling has been used as it is the most accurate of the available methods. Index Terms --  Neutron flux monitoring, area, pulse

A Study on Effect of Operating Conditions on Gerotor Pump Performance

One of the important accessories of the lubrication system of an aero-engine is the oil pump which consists of multiple pumps with tandem gerotor elements housed in a single casing. This paper presents the volumetric efficiency variation of a single-stage gerotor pump specially designed for aero-engine by conducting experiments at on and off-design conditions and comparing it with the CFD analysis. A Gerotor pump having fixed geometrical parameters designed based on a  athematical 1D model using MatLab and AMESim is manufactured and tested. Performance evaluation of these pumps for pressure and temperature has been discussed in this paper. Commercial CFD code ANSYS-Fluent with a standard k- ε turbulence model has been used for performance evaluation of gerotor pump. Flow characteristics studies on the prototype pump indicate that simulation results closely matched the experimental data. The study concludes that the simulation method adopted is appropriate for predicting the performance of the gerotor pump and the contribution of outlet pressure to the pump volumetric efficiency is significant

A novel conductometric titration approach for rapid determination of boron

21-30In laboratories dealing with radioactive samples it is important to minimize both the sample size and also the associated waste generated in an analysis. To meet this objective a rapid conductometric titration technique is developed to determine boron in the moderators of Pressurized Heavy Water Reactors (PHWR’s). Using this novel PC interfaced titration facility a minimum tenfold reduction in sample size is achieved compared to conventional conductometric titration. Determination of boron is based on the conversion of extremely weak boric acid to better conducting boron mannitol complex and titrating the complex against NaOH. Various parameters affecting the analysis, when moving from large to small sample size, are analyzed and optimized. The technique is primarily proposed for the assay of boron (≥0.5 ppm) during reactor startup. Each analysis requires less than 10 min. The detection limit is 0.5 ppm and the precision obtained at this level is 4.6% RSD. The technique is a good alternative to less sensitive carminic acid based spectrophotometric method

Lanthanide luminescence based probe for detection of picric acid

1041-1047Europium fluorescence is significantly enhanced through ligand sensitization using aromatic benzene mono and di carboxylic acids as ligands in aqueous solution. By optimising metal to ligand ratio and solution pH, it is established that the enhancement is maximum with isophthalic and terephthalic acid. Phosphorescence of isophthalic acid is recorded and its triplet energy level is found to be at 25633 cm-1; just above the fluorescing energy level of Eu3+. On complexation with these ligands though the europium luminescence is enhanced by orders of magnitude, the europium lifetime increased marginally. Addition of picric acid resulted in the quenching of europium luminescence in europium-isophthalic acid complex. Based on this quenching, a fluorimetric method is developed for the estimation of picric acid in aqueous solution. Picric acid in aqueous solution could be estimated down to 0.23 ppm. Common cations and anions found in natural waters did not interfere in the analysis. The precision in measurement is within 5% RSD in the entire range of measurement

Lanthanide luminescence based probe for detection of picric acid

Europium fluorescence is significantly enhanced through ligand sensitization using aromatic benzene mono and di carboxylic acids as ligands in aqueous solution. By optimizing metal to ligand ratio and solution pH, it is established that the enhancement is maximum with iso-phthalic and tere-phthalic acid. Phosphorescence of isophthalic acid is recorded and its triplet energy level is found to be at 25633 cm-1; just above the fluorescing energy level of Eu3+. On complexation with these ligands though the europium luminescence is enhanced by orders of magnitude, the europium lifetime increased marginally. Addition of picric acid resulted in the quenching of europium luminescence in europium-isophthalic acid complex. Based on this quenching, a fluorimetric method is developed for the estimation of picric acid in aqueous solution. Picric acid in aqueous solution could be estimated down to 0.23 ppm. Common cations and anions found in natural waters did not interfere in the analysis. The precision in measurement is within 5 % RSD in the entire range of measurement

Increase in perceived case suspiciousness due to local contrast optimisation in digital screening mammography

Item does not contain fulltextOBJECTIVES: To determine the influence of local contrast optimisation on diagnostic accuracy and perceived suspiciousness of digital screening mammograms. METHODS: Data were collected from a screening region in the Netherlands and consisted of 263 digital screening cases (153 recalled,110 normal). Each case was available twice, once processed with a tissue equalisation (TE) algorithm and once with local contrast optimisation (PV). All cases had digitised previous mammograms. For both algorithms, the probability of malignancy of each finding was scored independently by six screening radiologists. Perceived case suspiciousness was defined as the highest probability of malignancy of all findings of a radiologist within a case. Differences in diagnostic accuracy of the processing algorithms were analysed by comparing the areas under the receiver operating characteristic curves (A(z)). Differences in perceived case suspiciousness were analysed using sign tests. RESULTS: There was no significant difference in A(z) (TE: 0.909, PV 0.917, P = 0.46). For all radiologists, perceived case suspiciousness using PV was higher than using TE more often than vice versa (ratio: 1.14-2.12). This was significant (P <0.0083) for four radiologists. CONCLUSIONS: Optimisation of local contrast by image processing may increase perceived case suspiciousness, while diagnostic accuracy may remain similar. KEY POINTS: Variations among different image processing algorithms for digital screening mammography are large. Current algorithms still aim for optimal local contrast with a low dynamic range. Although optimisation of contrast may increase sensitivity, diagnostic accuracy is probably unchanged. Increased local contrast may render both normal and abnormal structures more conspicuous.1 april 201

Using Parahydrogen Induced Polarization to Study Steps in the Hydroformylation Reaction.

A range of iridium complexes, Ir(η3-C3H5)(CO)(PR2R’)2 (1a-1e) [where 1a, PR2R’ = PPh3, 1b P(p-tol)3, 1c PMePh2, 1d PMe2Ph and 1e PMe3] were synthesized and their reactivity as stoichiometric hydroformylation precursors studied. Para-hydrogen assisted NMR spectroscopy detected the following intermediates: Ir(H)2(η3-C3H5)(CO)(PR2R’) (2a-e), Ir(H)2(η1-C3H5)(CO)(PR2R’)2 (4d-e), Ir(H)2(η1-C3H5)(CO)2(PR2R’) (10a-e), Ir(H)2(CO-C3H5)(CO)2(PR2R’) (11a-c), Ir(H)2(CO-C3H7)(CO)2(PR2R’) (12a-c) and Ir(H)2(CO-C3H5)(CO)(PR2R’)2 (13d-e). Some of these species exist as two geometric isomers according to their multinuclear NMR characteristics. The NMR studies suggest a role for the following 16 electron species in these reactions: Ir(η3-C3H5)(CO)(PR2R’), Ir(η1-C3H5)(CO)(PR2R’)2, Ir(η1-C3H5)(CO)2(PR2R’), Ir(CO-C3H5)(CO)2(PR2R’), Ir(CO-C3H7)(CO)2(PR2R’) and Ir(CO-C3H5)(CO)(PR2R’)2. Their role is linked to several 18 electron species in order to confirm the route by which hydroformylation and hydrogenation proceeds

The evaluation of acoustic characteristic performance on natural sound absorbing materials from cogon grass waste

In the past few decades, synthetic fibers are been used widely in the field of sound absorption due to their superior characteristics such as durable and chemical resistant. However, there are several disadvantages of synthetic fibers such as non-biodegradability and hazards to the health of human. In this research, the natural sound absorber from cogon grass was investigated. The objective of the research was to evaluate the performance of cogon grass physical characteristics on its acoustical behavior, to evaluate the effect of sodium hydroxide (NaOH) treatment times on physical and acoustical characteristics of cogon grass, to investigate the decay effects after it was left over for twelve months and lastly to compare and verify the acoustical results with theoretical models based on (Delany-Bazley and Miki Model). The measurement of acoustical characteristics which are sound absorption coefficient (SAC) and noise reduction coefficient (NRC) were done by using impedance tube method (ITM). The samples of cogon grass were tested in a way of the untreated and treated with NaOH in varied soaked hours which are one, two, three, four and five hours. Scanning electron microscope (SEM) and density kit were used to investigate physical characteristics. The research confirmed that physical characteristics of tortuosity and airflow resistivity values tend to increase with the increment of treatment times, but the density and porosity tend to decrease. Untreated samples were tested with varied thicknesses of 10, 20, 30, 40 and 50mm. The results show SAC value increases when the thickness of the sample was increased. Treated samples results show the least treated sample (1 hour) reached the maximum SAC value and indicated the highest value of NRC which is 0.50. The results also show a reduction in sound absorption value after the samples were left for twelve months. Verification parts demonstrated that Delany-Bazley and Miki Model can predict approximately pattern compared with ITM results because of the theoretical models are developed by a simple empirical model approach. Overall, cogon grass samples have the good characteristics to be an acoustic material component