Atom Indonesia (E-Journal)
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The Effect of Pretreatment by using Electron Beam Irradiation on Oil Palm Empty Fruit Bunch
Get PDFOil palm empty fruit bunch (OPEFB) is a potential type of lignocellulosic biomass for second-generation bioethanol production. The pretreatment process is an important process in the series of processes to produce bioethanol. This research aims to study the effects of pretreatment process by using electron beam irradiation to OPEFB’s characterization as raw materials for the hydrolysis reaction to produce monomer sugars which will be fermented into ethanol. The untreated and treated OPEFB are characterized in terms of their physical and chemical properties. Analysis results of the compositional analysis by using NREL/TP-510-42618 method show that after pretreatment by using electron beam irradiation, OPEFB's total lignin content is changed little while its cellulose and hemicellulose contents tend to decrease with increasing irradiation dose. X-ray diffraction (XRD) analysis shows that there is a decrease of crystallinity compared to untreated OPEFB, except for 200-kGy irradiated OPEFB. The highest decrease of crystallinity was shown by 300-kGy irradiated OPEFB. Further, crystallite sizes of treated OPEFBs are not significantly different from the untreated, except for the 200-kGy irradiated OPEFB. Irradiation pretreatment also increases specific surface area, pore volume, and pore size. The IR spectra analysis show the absorption of cellulose, hemicellulose, and lignin.Received: 07 January 2015; Revised:15 May 2015; Accepted: 17 May 2015
Performance Analysis of AP1000 Passive Systems during Direct Vessel Injection (DVI) Line Break
Get PDFGeneration II Nuclear Power Plants (NPPs) have a design weakness as shown by the Fukushima accident. Therefore, Generation III+ NPPs are developed with focus on improvements of fuel technology and thermal efficiency, standardized design, and the use of passive safety system. One type of Generation III+ NPP is the AP1000 that is a pressurized water reactor (PWR) type that has received the final design acceptance from US-NRC and is already under construction at several sites in China as of 2015. The aim of this study is to investigate the behavior and performance of the passive safety system in the AP1000 and to verify the safety margin during the direct vessel injection (DVI) line break as selected event. This event was simulated using RELAP5/SCDAP/Mod3.4 as a best-estimate code developed for transient simulation of light water reactors during postulated accidents. This event is also described in the AP1000 design control document as one of several postulated accidents simulated using the NOTRUMP code. The results obtained from RELAP5 calculation was then compared with the results of simulations using the NOTRUMP code. The results show relatively good agreements in terms of time sequences and characteristics of some injected flow from the passive safety system. The simulation results show that the break of one of the two available DVI lines can be mitigated by the injected coolant flowing, which is operated effectively by gravity and density difference in the cooling system and does not lead to core uncovery. Despite the substantial effort to obtain an apropriate AP1000 model due to lack of detailed geometrical data, the present model can be used as a platform model for other initiating event considered in the AP1000 accident analysis.Received: 2 November 2015; Revised: 19 April 2016; Accepted: 25 April 201
Comparison of Radiosensitivity of Human Chromosomes 1, 2 and 4 from One Healthy Donor
Get PDFIn general, it was assumed that the chromosome aberration induced by ionizing radiation is proportional to the chromosome size. From this viewpoint, the higher chromosome size, the more resistant to radiation. However, different opinions, in which chromosomes are particularly sensitive or resistant to radiation, are also still followed until now. Here in this research, we compared the chromosome sensitivity between chromosomes number 1, 2, and 4 using the FISH (fluorescence in situ hybridization) technique. From this research, we expect that the information obtained could show clearly whether a longer chromosome is more frequently involved in translocations and also more resistant to radiation than a shorter one. The type of chromosome aberration considered was limited only to translocation and we used one sample donor in order to avoid donor variability. The whole blood from a healthy female was irradiated with γ-rays with doses of 1, 3 and 5 Gy, respectively. Isolated lymphocytes from the whole blood were then cultured for 48 hours. After the culture process was completed, preparations of harvest and metaphase chromosomes were carried out. Chromosomes 1, 2, and 4 were stained with different fluorochromes. The translocation of each chromosome at each dose point was subsequently evaluated from 50 images obtained from an automated metaphase finder and capturing system. An additional analysis was performed to identify which chromosome arm was more frequently involved in translocation. Further analyses were also conducted with the aim of determining which chromosome band had a higher frequency of radiation-induced breakage. The experimental results showed that chromosome number 4 was more frequently involved in translocations compared to chromosomes 1 and 2 at 5 Gy. In contrast, at doses of 1 and 3 Gy translocations involving chromosomes number 1 and 2 were more numerous compared to the ones involving chromosome 4. However, if the number of translocation was accumulated for all the doses applied, the chromosome number 4 was the chromosome most frequently involved in translocations. Breakpoint analysis revealed that in chromosome 1, chromosome 2, and chromosome 4, the highest chromosome bands as break position were in band q32, p13, and q21, respectively. It can be concluded that chromosome 4 is more sensitive to radiation in all doses point, despite having less DNA content than chromosomes 1 and 2. Thus, it was showed that our research cannot support the general assumption about chromosome aberration induced by radiation being proportional to DNA content.Received: 29 September 2015; Revised: 29 March 2016; Accepted: 31 March 201
Identification of the Second Mutation of BADH2 Gene Derived from Rice Mutant Lines Induced by Gamma Rays
Get PDFThe BADH2 gene acts as suppressor of 2-acetyl-1-pyrolline (2AP) biosynthesis in plants. 2AP is the volatile compound which provides fragrance in rice. Biosynthesis of 2AP occurs when BADH2 loses its function as suppressor gene. Aromatic rice cultivars naturally incur mutation of BADH2 gene at 8 bp. In this experiment, aromatic mutant rice lines derived from irradiation of Sintanur cultivar by gamma rays with dose of 100 Gy were studied in molecular level. These mutant lines were characterized at the M10 plant generation under the assumption that genetically these aromatic mutant rice lines were homozygotic. Several primers related to aroma in rice have been used for polymerase chain reaction (PCR) in a thermal cycler instrument. Gel electrophoreses were carried out using 1.5% agarose in TAE buffer. DNA fragments at 254 bp and 355 bp (base pair) were taken and amplified by primer for nucleotide sequencing of these fragments. Molecular identification and characterization after electrophoresis showed that the mutant line from AR1020 can be differentiated from AR.1080 at 254 bp. Nucleotide sequence data from of these DNA fragments showed that point mutations (deletions and substitutions) occurred at the BADH2 gene in exon 7; those are called second mutation and were caused by gamma rays effects. The Sintanur variety was used as check cultivar and its DNA sequence was compared to that of the AR.1020 mutant line. The results from both DNA sequences (from cv. Sintanur and AR.1020) derived from fragments at 254 bp show that point mutations occurred within exon 7 and earlier stop codon occurred in the AR.1020 mutant rice line. Further, the use of EA primer in PCR resulted in detection of deletion and substitution of nucleotides in the AR.1020 mutant line
Characterization of Zircaloy-4 after Gaseous Hydriding at the Temperature Range of 350-600°C
Get PDFThe degradation of the mechanical properties of zircaloy-4 as nuclear fuel cladding is inevitable due to its interaction with hydrogen during normal reactor operation. This experiment observed the occurence of hydride phases after gaseous hydriding with hydrogen at elevated temperature, and their effects were evaluated based on the material's microstructure and mechanical properties. The zircaloy-4 cladding materials were annealed for two hours. It was followed by hydriding with the pressure from 100 up to 1200 mbar at various temperatures of 350°C, 500°C,550°C and 600°C. The pressure-composition-isotherm (PCI) diagram showed that the hydrogen absorbed by specimen namely 0.18% wt, 0.38% wt, 0.44% wt and 0.74% wt at 350°C, 500°C, 550°C and 600°C, respectively. This result confirmed that the hydrogen content were 10, 128, 250, and 1357 ppm at 350°C,500°C,550°C, and 600°C, respectively, as measured by an ONH analyzer. X-ray diffraction showed that δ-hydride peaks were very weak based on fitting with the hydride database. The results from optical microscope and scanning electron microscope confirmed the presence of hydrides at the specimens, identified by the growth of needle-like structure at those temperatures.Received: 5 January 2016; Revised: 15 June 2016; Accepted: 20 August 201
A Fuzzy Probability Algorithm for Evaluating the AP1000 Long Term Cooling System to Mitigate Large Break LOCA
Get PDFComponents of nuclear power plants do not always have historical failure data to probabilistically evaluate their reliability characteristics. To overcome this drawback, an alternative approach has been proposed by involving experts to qualitatively justifybasic event likelihood occurences. However, expert judgments always involve epistemic uncertainty and this uncertainty needs to be quantified. Existing fault tree analysis quantifies uncertainty using Monte Carlo simulation, which is based on probability distributions. Since expert judgments are not described in probability distributions, Monte Carlo simulation is not appropriate for evaluating epistemic uncertainty. Therefore, a new approach needs to be developed to overcome this limitation. This study proposes a fuzzy probability algorithmtoevaluate epistemic uncertainties in fault tree analysis.In the proposed algorithm, fuzzy probabilities are used to represent epistemic uncertainties of basic events, intermediate events, and the top event. To propagate and quantify epistemic uncertainty in fault tree analysis, a fuzzy multiplication rule and a fuzzy complementation rule are applied to substitute the AND Boolean and OR Boolean gates, respectively. To see the feasibility and applicability of the proposed algorithm, a case-based experiment on uncertainty evaluation of the AP1000 long term cooling system to mitigate the large break loss of coolant accident is discussed.The result shows that the best estimate probability to describe the failure of AP1000 long term cooling system generated by the proposed algorithmis3.15×10-11, which is very closed to the reference value of 1.11×10-11.This result confirms that the proposed algorithm offers a good alternative approach to quantify uncertainties in probabilistic safety assessment by fault tree analysis.Received:22 October 2014; Revised: 24 June 2015; Accepted: 29 June 201
Identification and Angular Distribution of Residual Radionuclides Detected on the Wall of BATAN’s Cyclotron Cave
Get PDFDetection and measurement of radiation sources around BATAN’s cyclotron facilities in Serpong are required as an early step to avoid radiation impacts on the radiation employees who work with the cyclotron. In this paper, radiation emitted from the wall of the CS-30 cyclotron cave are detected and measured using an NaI(Tl) detector coupled with a pocket multichannel analyzer (MCA) at a counting time of 30 minutes for each sampling point on the wall. The sampling points were in the directions of within ±150o with respect to the incoming proton beams, and the measurements were conducted at heights between 1.2 m and 1.8 m off the floor for every sampling point. The experimental results indicate that Co-60 and Cs-134 detected on the cyclotron cave wall are major radionuclides that contribute to the emitted gamma radiation. The distribution of the gamma ray intensities given off by Co-60 and Cs-134 depend on the angle and position of the sampling points. In general the highest gamma ray rates can be found in the area around 0o relative to the incoming proton beams. In addition, no other radioactive sources are significantly detected on the wall. The maximum exposure measured on the wall surface was much less than the permissible occupational exposure for radiation workers and general public.Received: 27 March 2015; Revised: 30 September 2015; Accepted: 15 December 2015