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Ilman M.N.,Gadjah Mada University | Kusmono,Gadjah Mada University | Muslih M.R.,National Nuclear Energy Agency of Indonesia BATAN | Subeki N.,Gadjah Mada University | Wibowo H.,Gadjah Mada University
Materials and Design | Year: 2016

The demand for lightweight structures in ship fabrication to improve performance and fuel savings has led to increasing use of thin-section structures. However, welding such structures often produces problems such as distortion and residual stress. The present investigation is aimed to mitigate distortion and residual stress using static thermal tensioning (STT) to improve fatigue performance in AA 5083 metal inert gas (MIG) welded joints. The STT treatments were performed by cooling the weld zone and its adjacent area during welding whereas both sides away from the weld were heated at various temperatures of 100, 200 and 300 °C to generate thermal gradient. Subsequent experiments including distortion measurements, microscopical examination, hardness and tensile tests, measurements of residual stresses using neutron diffraction method and fatigue crack growth tests combined with SEM fractography were conducted. Results showed that an increase in heating temperature reduced convex longitudinal out of plane distortion. The minimum longitudinal out of plane distortion was achieved at a heating temperature of 200 °C owing to the balance between buckling distortion induced by welding and that generated by static differential heating which opposed the weld distortion. Under such condition, fatigue crack growth performance was improved. © 2016 Elsevier Ltd. Source

Ariani M.,Bandung Institute of Technology | Su'ud Z.,Bandung Institute of Technology | Monado F.,Bandung Institute of Technology | Waris A.,Bandung Institute of Technology | And 4 more authors.
Applied Mechanics and Materials | Year: 2013

In this study gas cooled reactor system are combined with modified CANDLE burn-up scheme to create small long life fast reactors with natural circulation as fuel cycle input. Such system can utilize natural Uranium resources efficiently without the necessity of enrichment plant or reprocessing plant. Therefore using this type of nuclear power plants optimum nuclear energy utilization including in developing countries can be easily conducted without the problem of nuclear proliferation. In this paper, optimization of Small and Medium Long-life Gas Cooled Fast Reactors with Natural Uranium as Fuel Cycle Input has been performed. The optimization processes include adjustment of fuel region movement scheme, volume fraction adjustment, core dimension, etc. Due to the limitation of thermal hydraulic aspects, the average power density of the proposed design is selected about 75 W/cc. With such condition we investigated small and medium sized cores from 300 MWt to 600 MWt with all being operated for 10 years without refueling and fuel shuffling and just need natural Uranium as fuel cycle input. The average discharge burn-up is about in the range of 23-30% HM. © (2013) Trans Tech Publications, Switzerland. Source

Purba J.H.,National Nuclear Energy Agency of Indonesia BATAN
Progress in Nuclear Energy | Year: 2014

Fault tree analysis (FTA) is a graphical model which has been widely used as a deductive tool for nuclear power plant (NPP) probabilistic safety assessment (PSA). The conventional one assumes that basic events of fault trees always have precise failure probabilities or failure rates. However, in real-world applications, this assumption is still arguable. For example, there is a case where an extremely hazardous accident has never happened or occurs infrequently. Therefore, reasonable historical failure data are unavailable or insufficient to be used for statistically estimating the reliability characteristics of their components. To deal with this problem, fuzzy probability approaches have been proposed and implemented. However, those existing approaches still have limitations, such as lack of fuzzy gate representations and incapability to generate probabilities greater than 1.0E-3. Therefore, a review on the current implementations of fuzzy probabilities in the NPP PSA is necessary. This study has categorized two types of fuzzy probability approaches, i.e. fuzzy based FTA and fuzzy hybrid FTA. This study also confirms that the fuzzy based FTA should be used when the uncertainties are the main focus of the FTA. Meanwhile, the fuzzy hybrid FTA should be used when the reliability of basic events of fault trees can only be expressed by qualitative linguistic terms rather than numerical values. © 2014 Elsevier Ltd. All rights reserved. Source

Purba J.H.,National Nuclear Energy Agency of Indonesia BATAN | Lu J.,Intelligent Systems Technology, Inc. | Zhang G.,Intelligent Systems Technology, Inc.
International Journal of Computational Intelligence and Applications | Year: 2014

Fault tree analysis for nuclear power plant probabilistic safety assessment is an intricate process. Personal computer-based software systems have therefore been developed to conduct this analysis. However, all existing fault tree analysis software systems only accept quantitative data to characterized basic event reliabilities. In real-world applications, basic event reliabilities may not be represented by quantitative data but by qualitative justifications. The motivation of this work is to develop an intelligent system by fuzzy reliability algorithm in fault tree analysis, which can accept not only quantitative data but also qualitative information to characterized reliabilities of basic events. In this paper, a newly-developed system called InFaTAS-NuSA is presented and its main features and capabilities are discussed. To benchmark the applicability of the intelligent concept implemented in InFaTAS-NuSA, a case study is performed and the analysis results are compared to the results obtained from a well-known fault tree analysis software package. The results confirm that the intelligent concept implemented in InFaTAS-NuSA can be very useful to complement conventional fault tree analysis software systems. © Imperial College Press. Source

Bachtiar E.W.,University of Indonesia | Amir L.R.,University of Indonesia | Suhardi P.,University of Indonesia | Abas B.,National Nuclear Energy Agency of Indonesia BATAN
Interventional Medicine and Applied Science | Year: 2016

Objective: To examine the degradation of three scaffolds composed of hydroxyapatite/tricalcium phosphate (HA/TCP) with 70:30 ratio, HA/TCP with 50:50 ratio, and HA/TCP/chitosan scaffold as analyzed by the RNA expression of matrix metalloprotease 2 (MMP2), interleukin 13 (IL13), and tartrate-resistant acid phosphatase (TRAP) genes. Methods: The three tested scaffolds and dental pulp stromal cells (DPSCs) were transplanted into the mandibular bone defect of six young male Macaca nemestrina. Defect on the left mandible served as the experimental group and the right mandible served as control group (split mouth design). The biopsies were retrieved at 0, 2, and 4 weeks after cell-scaffold transplantation. The expression of MMP2, IL13, and TRAP was analyzed by real-time PCR (RT-PCR). Results: The inflammatory cells were still detected in areas where active bone and blood vessel formation occurred. The remnants of scaffold biomaterials were rarely seen. The expression of MMP2, IL13, and TRAP was observed in all samples. Their expressions were increased at week 4 and the decrease of TRAP gene expression in the experimental group was found higher than the control group. TRAP gene in the HA/TCP/chitosan group was found to be the highest at week 2 and lowest at week 4. Conclusions: Degradation of the scaffold did not induce higher inflammatory response compared to the control yet it induced more osteoclast activity. © 2016 The Author(s). Source

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