Atom Indonesia (E-Journal)
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Present Status of Marine Radioecology in Jakarta Bay
Get PDFOperation of nuclear facilities such as research reactor and it’s supporting installation in Serpong Nuclear Area may release controlled radionuclides to Cisadane River and then it would flow to Jakarta Bay. There are limited marine radioecology studies or radionuclides monitoring at Jakarta Bay. Therefore monitoring of 239/240Pu and 137Cs was carried out from Tanjung Pasir to Tanjung Kerawang. The ERICA Assessment Tool was used to evaluate radiological risk in the marine environment of Jakarta Bay area. The 137Cs concentration in sea water and sea sediments were in range of 0.17 – 1.17 Bq.m-3 and 0.34 – 1.21 Bq.kg-1, respectively. Moreover, result of 239/240Pu measurement showed that concentration at sea water and sea sediment were range from MDA – 0.53 mBq.m-3 and 2.64 – 55.70 mBq.kg-1 respectively. The results of risk analysis were indicated that all the total dose rates per organism were millions time lower than the screening rate (10 mGy.h-1)
Phosphate Solubilizing Study on the Determination of Inoculant Dose and Composition for Biofossi Fertilizer
Get PDFPhosphorus availability becomes a major problem on the productivity of soil and rice in Indonesia. Utilization of P source which has a slow release property is one of the solutions to these problems. Biofossi fertilizer is a natural phosphate organic fertilizer which is enriched with phosphate solubilizer bacteria (PSB), to improve the solubility of P and absorption by the plant so that P fertilization becomes more efficient. Experiment conducted on January 2015 at the experimental station of Agriculture Faculty-Padjadjaran University, Bandung, located in Ciparay, West Java. The aim of the experiment was to determine the PSB composition and its inoculation dose toward natural phosphate. Inoculum used was of Bacillus sp and Pseudomonas sp, which was injected to a carrier material. Through previous test results, the carrier used had a composition of 50 % peat + 28 % compost + 5 % humic acid + 2 % nutrition + 15 % rice husk. To test the dose of PSB inoculation, experimental design of factorial randomized complete block was applied. As the first factor was P2O5 content in the phosphate source, consisting of four levels as follows: (1) p0 = without P2O5 (as control); (2) p1 = 22 % P2O5 (163 kg ha-1 natural phosphate from Blora); (3) p2 = 26 % P2O5 (138 kg ha-1 natural phosphate from Morocco); (4) p3 = 36 % P2O5 (100 kg ha-1 SP-36 fertilizer). Second factor was the combination of dose and type of PSB inoculant, consisting of seven levels as follows: (1) b0 = without inoculation of PSB (as control); (2)b1 = Bacillus sp inoculant in the dose of 1 kg ha-1; (3)b2 = Bacillus sp inoculant in the dose of 2 kg ha-1; (4) b3 = Pseudomonas sp inoculant in the dose of 1 kg ha-1; (5)b4 = Pseudomonas sp inoculant in the dose of 2 kg ha-1; (6)b5 = Bacillus sp + Pseudomonas sp consortium in the dose of 1 kg ha-1; (7) b6 = Bacillus sp + Pseudomonas sp consortium in the dose of 2 kg ha-1. By using the 32P radioisotope techniques it was known that a consortium of bacteria Bacillus sp + Pseudomonas sp was capable of dissolving P on the treatment p0, as well as in the treatments p1, p2 and p3. In this treatment, some of the highest response was obtained, i.e. the grain dry weight, P uptake and P fertilizer efficiency
The Analysis of Hierarchical Structure of Mesoporous Silica in Nanometer Scale by Small Angle Scattering Method
Get PDFThe analysis of hierarchical structure of mesoporous silica material with template of cetyltrimethylammoniumbromide (CTAB) with co-surfactants of tetra-methylammonium hydroxide (TMAOH) and Triton X-100 was conducted by using the technique of small angle scattering (SAS) using neutron (SANS) and X-ray (SAXS). The analysis was supported by the data of nitrogen absorption and electron microscopy. The analysis showed that the concentration of CTAB affected the characteristics and pore structures of particles. The increase of co-surfactant concentrations tended to form particles that were more uniform in size and more regular in the shape of the sphere. The results of SAS analysis showed that the morphology, shape, and size of the large particles were arranged by smaller (primary or secondary) particles that had pores. The variation of surfactant templates had influenced the formation of pore structure. For CTAB-TMAOH, it would had resembled MCM-41 type which has a hexagonal structure, whereasfor CTAB-Triton X-100, it would have resembled MCM-48 type which has a cubic structure. The particles that have a high surface area which resembled pore structure MCM-41 has been able to set up by using 0.25 M of CTAB with 0.040 M of TMAOH. Moreover, the particles which resembled pore structure MCM-48 were able to set up by using 0.03 M of Triton X-100 with 0.4 M of CTAB. The analysis of SANS data that was supported by electron microscopy results is entirely showing a complete information of the particles formed by each template. Whereas SAXS analysis that supported by nitrogen adsorption method is fully confirming the information of pore characteristics
Fungal Population and Aflatoxin Contamination on Stored Gamma-Irradiated Nutmeg (Myristica fragrans) Kernels
Get PDFA study on the effectivenessof gamma irradiation at doses of 5 and 10 kGy on fungal population, Aspergillus flavus strains, and aflatoxin B1 contamination on stored nutmeg kernels was conducted. The kernels were collected from seeds in a period of one week from the ground at North Sulawesi Province, Indonesia.Dried shelled kernels with ±10 %moisture content, packed in polyethylene bags at 2.1 kg/bag, were irradiated at 5 and 10 kGy and stored at ambient temperature (28°C) for 2 and 4 months. Kernel moisture content, fungal population, and aflatoxin B1 were determined before and after irradiation, and after 2 and 4 months of storage. Results showed that fungal population was reduced with the increasing irradiation dose. Five species of fungi were isolated, i.e., Aspergillus flavus, A. niger, Cladosporium cladosporioides, Eurotium chevalieri, and Penicillium citrinum. A total of twelve A. flavus strains were isolated, five strains from unirradiated kernels and five and two strains from irradiated kernels at doses 5 and 10 kGy, respectively. Among these strains, 58 % were capable of producing L sclerotia and 25 % were identified as toxigenic. Kernel moisture during storage was 7.3 % and no aflatoxin B1 was detected before and after irradiation, and after2 and 4 months of storage duration
Polymorphism of XRCC1 Gene Exon 6 (Arg194Trp) in Relation to Micronucleus Frequencies in Hospital Radiation Workers
Get PDFThe genetic polymorphism of DNA repair gene plays some important role in regulating individual sensitivity to ionizing radiation, maintaining DNA integrity, and preventing cancer and DNA damage.XRCC1 as one of the members ofbase excision repair (BER) is involved in the repairement of oxidized bases and single-strand breaks DNA after exposure by ROS, including ionizing radiation. This study was aimed to examine the correlation between XRCC1 exon 6 gene polymorphism and MN frequency in radiation workers and their relation to age, gender, smoking status and years of exposure. This study involved 81 hospital radiation workers and 20 controls from several hospitals in Indonesia. Genotyping of XRCC1exon 6 gene polymorphism and MN assay were performed using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and Cytokinesis-Block Micronucleus assay (CBMN assay), respectively. The results indicated that MN frequency was significantly higherin the exposed workers than in the controls (15.38±7.72 versus 9±5.49; p = 0.001).Radiation workers with heterozygous alleles for XRCC1 polymorphisms showed a significantly higher MN frequency than controls with the same genotypes (17.5±8.36 versus 7.44±5.05; p = 0.002). The confounding factors, like gender and age, were significantly associated with increased MN frequency both in radiation workers and controls. Smoking status was significantly associated with MN frequency in the controls only, while years of exposure did not affect MN frequency either in radiation workers or controls. These results suggest that the genetic polymorphism of XRCC1 gene exon 6 with a mutant heterozygous/ CT variant demonstrated an association with the extent of DNA damage in the hospital radiation workers in this study. In the subsequent studies, it is necessary to examine the DNA repair genes polymorphism in populations with controlled non-genetic factors, such as lifestyles, environments, and exercises that affect the MN frequency as a biomarker of DNA damage
An Experimental Analysis on Nusselt Number of Natural Circulation Flow in Transient Condition Based on the Height Differences between Heater and Cooler
Get PDFA better understanding on the phenomenon of natural circulation flow for cooling systems is necessary prior to improving the safety of nuclear power plant, not only in normal operation but also in accident conditions. One way to understand this phenomenon is by analyzing the Nusselt number in various geometrical dimensions through experimentation. The purpose of this study is to understand natural circulation phenomenon in transient condition by varying height differences between heater and cooler. To achieve this purpose, an experiment apparatus called NC-Queen was developed and arranged to enable three variations of height differences between heater and cooler, i.e., 1.4 m, 1.0 m, and 0.3 m. It is made of a stainless steel tube with a diameter of 1 inch, arranged in rectangular shape 6.4 m in length, and uses water as coolant. The initial temperature of the heater was set at 90 °C. The Nusselt number was obtained by calculating the flow rate as a function of transient temperature. The results confirm that height differences affect thermal properties and flow region based kinetics characteristics of water. In initial condition, decreasing height difference from 1.4 m to 1.0 m resulted in flow rate reduction of 16.7 %, while decreasing height difference from 1.4 m to 0.3 m resulted in a 39.1 % flow rate reduction. In final condition, the flow rate reductions were 75 % and 82.6 %, respectively. Meanwhile, in initial condition, the Nusselt number for height difference reduction from 1.4 m to 1.0 m and from 1.4 m to 0.3 m decreased by 30.5 % and 74.6 %, respectively, while for final condition, the Nusselt number decreased by 11.9 % and 67.4 %, respectively. The new constants in relationship between Nusselt number and the height difference are a = 20.06 and b = 0.56. The dominance of turbulent flow provides a good safety margin with indications of the large amount of heat released
A Novel Technique for Removal of High Density White Spot Noise from Digital Neutron Radiographic Images
Get PDFThis paper proposes a novel technique of adaptive switching alternative median (ASAM) filter for high-density white spot noise removal. The ASAM filter is composed of two blocks filtering, namely main and secondary block filtering, respectively. The proposed secondary block filtering is a new technique in high-density impulse noise removal and the main contribution of this research. The ASAM algorithm was tested on the standard 8-bit gray-scale, 512×512 pixel Lena image and a real neutron radiographic image. The results showed significant reduction of white spot noise in both types of images through visual inspection. To measure the performance of noise removal in simulation test we measured the peak signal-to-noise ratio (PSNR), structural similarity (SSIM) index, and denoising time, and in real application tests we measured signal-to-noise ratio (SNR). From the experiments of simulation test, at the highest level noise of 95 % the obtained PSNR and SSIM are 23.584 dB and 0.696 respectively. These are higher than the results of other algorithms that are 16.697 dB and 0.475, respectively, for DBA, 16.696 dB and 0.408 for NAFSM, and 18.860 dB and 0.568 for NASNLM. The denoising times for DBA, NAFSM, NASNLM, and ASAM were obtained as 6.469 s, 5.186 s, 36.735 s, and 5.197 s respectively. From the experiments of real application test we obtained the SNR for DBA, NAFSM, NASNLM, and ASAM as 32.42 dB, 6.01 dB, 18.77 dB, and 32.96 dB, respectively. In general, these results show that ASAM filter is superior to the existing filtering methods. The ASAM filter improved the image restoration quality, especially in removing the high-density white spot noise, and was able to yield good filtering result which exhibits better PSNR, SSIM, denoising time, and qualitative visual inspection