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[en] One of the challengeable works for the Iodine-Sulfur water splitting cycle is to establish the thermodynamic model for HI section due to the difficulty of the modeling of reactive distillation column and non-ideal characteristic of HIx solution. In order to predict partial pressure of HIx solution in the binary mixture (H2O-HI), the thermodynamic model for HIx solution need to be developed with a proper binary parameter set. In this study, Neumann's thermodynamic NRTL model for the HIx solution was reproduced and KAIST model (improved Neumann model) was proposed with new assumptions. The binary parameter set for binary mixture and ternary mixture was regressed by using the numerical muti-variable fitting method in MATLAB. We validated the KAIST model with the new binary parameter set through comparison with experimental data. Besides, we proposed the simple Liquid-Liquid Equilibrium (LLE) phase separation method. The proposed method can predict LLE separation around 30%∼34% of HI concentration with only total pressure calculation based on the KAIST model. In ternary mixture(H2O-HI- I2), taking the same procedure as in the binary mixture we get the new parameter set to better predict the partial pressure of HIx solution considering HI decomposition effect. We developed the two-step method for the hydrogen partial pressure calculation. We compared hydrogen partial pressures obtained by the KAIST model with those by the Neumann model
[en] [18F]FLT is a new radiopharmaceutical for cell proliferation. We compared [18F]FLT and [18F]FDG in in vitro cancer cell uptake and glucose effect. Method: In vitro cancer cell uptake of [18F]FLT was evaluated using SCC7(mouse squamous cell carcinoma). At 24 hours after seeding 1 x 106 cells/well in 6 well plates with RPMI 1640 medium, culture media were changed to medium with glucose free or glucose concentration of 100 mg/dl. Then, [18F]FLT 5 μCi/50 ml was added to each well. After incubation for 30, 60, 90, 120 minutes, cells were washed twice by PBS, and harvested using 0.25% trypsin-EDTA. After centrifugation and counting at gamma counter, cell uptake was calculated by % activity of cellular uptake to total activity of cell and supernatant. For comparison, same tumor cell uptake experiment was performed with [18F]FDG. Results: After incubation with SCC7 cell line for 30, 60, 90, 120 minutes, [18F]FLT showed 1.95%, 2.17%, 2.10% and 2.80% of cell uptake in glucose free media, respectively. The results [18F]FLT uptake in glucose 100 mg/dl media were 1.82%, 1.87%, 1.97%, and 2.94%, respectively. The results of [18F]FDG in glucose free media were 2.50%, 3.47%, 5.04%, and 10.4%, whereas those in glucose 100 mg/dl media were 1.60%, 1.79%, 1.53%, and 1.82%, respectively. Conclusion: In contrast to [18F]FDG, [18F]FLT uptake in cancer cell was not affected by glucose concentration. In physiologic glucose concentration, [18F]FLT uptake in SCC7 cell line was significantly higher than [18F]FDG uptake after 120 minutes incubation. In [18F]FLT PET imaging may not need fasting for preparation before imaging study. (authors)
[en] Retrospective evaluation of setup changes using the corrected position during helical tomotherapy. Head and neck cancer patients were randomly sampled and summarized into 3 groups: Group 1(32) Brain, Group 2 2(28)Maxillar, Nasal cavity, Group 3 (35) Nasopharynx(NPX), Tongue, Tonsil, and Oropharynx(OPX). In 3 groups, the statistical tests based on repeated measurements among 30 times of the duration of treatment by applying X, Y, Z axis errors, roll, weight changes, and vectors as variables. The statistical test results showed that there was no difference between x-axis (p = 0.458) and y-axis (p=0.986) and in roll (p = 0.037), weight change (p <0.001), and the vector (p <0.001). In addition, the pattern between the three groups based on the fraction revealed no difference in x-axis (p = 0.430) and roll (p = 0.299) but a difference in y-axis (.023), weight change (p = 0.001), and vector (p = 0.028). The results of the retrospective evaluation found the change in the group 3 with respect Y, Z, weight, and vector and a larger random error during the treatment including low neck
[en] Highlights: • The Welander problem was investigated using high-order numerical methods. • High-order numerical methods reduced numerical diffusion significantly for stability analysis. • High-order numerical methods were proved to be promising for natural circulation analysis. - Abstract: In this paper, high-order numerical methods are investigated in a system analysis-like code. The classical Welander oscillatory natural circulation problem, which resembles a simplified example for many types of natural circulation loops widely seen in nuclear reactor systems, was chosen to illustrate the applicability of such methods in system analysis codes, and to demonstrate the advantages of such methods over the low-order methods widely used in existing system analysis codes. As originally studied by Welander, the fluid motion in a differentially heated fluid loop can exhibit stable, weakly unstable, and strongly unstable modes. A theoretical stability map has also been originally derived from the stability analysis. Numerical results obtained in this paper show very good agreement with Welander's theoretical derivations. For stable cases, numerical results from both the high-order and low-order numerical methods agree well with the non-dimensional flow rate that were analytically derived. The high-order numerical methods give much less numerical errors compared to those using low-order numerical methods. For stability analysis, the high-order numerical methods perfectly predicted the stability map even with coarse mesh and large time step, while the low-order numerical methods failed to do so unless very fine mesh and time step are used. The result obtained in this paper is a strong evidence for the benefits of using high-order numerical methods over the low-order ones, when they are applied to simulate natural circulation phenomenon that has already gained increasing interests in many existing and advanced nuclear reactor designs.
[en] In this study, sub-cooled flow boiling critical heat flux tests at low pressure were conducted in a rectangular flow channel with one uniformly heated surface, using simulant fluid R-134a as coolant. The experiments were conducted under the following conditions: (1) inlet pressure (P) of 400-800 kPa, (2) mass flux (G) of 124-248 kg/m2s, (3) inlet sub-cooling enthalpy (ΔHi) of 12~ 26 kJ/kg. Parametric trends of macroscopic system parameters (G, P, Hi) were examined by changing inlet conditions. Those trends were found to be generally consistent with previous understandings of CHF behavior at low pressure condition (i.e. reduced pressure less than 0.2). A fluid-to-fluid scaling model was utilized to convert the test data obtained with the simulant fluid (R-134a) into the prototypical fluid (water). The comparison between the converted CHF of equivalent water and CHF look-up table with same operation conditions were conducted, which showed good agreement. Furthermore, the effect of surface wettability on CHF was also investigated by applying atmospheric pressure plasma (AP-Plasma) treatment to modify the surface characteristic. With AP-Plasma treatment, the change of microscopic surface characteristic was measured in terms of static contact angle. The static contact angle was reduced from 80° on original non-treated surface to 15° on treated surface. An enhancement of 18% on CHF values under flow boiling conditions were observed on AP-Plasma treated surfaces compared to those on non-treated heating surfaces.
[en] We present three nuclear/hydrogen-related R and D activities being performed at KAIST: air-ingressed LOCA analysis code development, gas turbine analysis tool development, and hydrogen-production system analysis model development. The ICE numerical technique widely used for the safety analysis of water-reactors is successfully implemented into GAMMA, with which we solve the basic equations for continuity, momentum conservation, energy conservation of the gas mixture, and mass conservation of 6 species (He, N2, O2, CO, CO2, and H2O). GAMMA has been extensively validated using data from 14 test facilities. We developed a tool to predict the characteristics of HTGR helium turbines based on the through flow calculation with a Newton- Raphson method that overcomes the weakness of the conventional method based on the successive iteration scheme. It is found that the current method reaches stable and quick convergence even under the off-normal condition with the same degree of accuracy. The dynamic equations for the distillation column of HI process are described with 4 material components involved in the HI process: H2O, HI, I2, H2. For the HI process we improved the Neumann model based on the NRTL (Non-Random Two-Liquid) model. The improved Neumann model predicted a total pressure with 8.6% maximum relative deviation from the data and 2.5% mean relative deviation, and liquid-liquid-separation with 9.52% maximum relative deviation from the data
[en] Highlights: • We model a 3-D numerical solute transport within crud deposit on PWR fuel pin. • Source term effect from radiolysis yield and recombination is minimal. • Lower crud porosity leads substantially higher concentration of solutes. • Thicker crud deposit generates substantially higher concentration of solutes. • High concentration of radiolysis species (H_2, O_2, and H_2O_2) can be directly related to corrosion issues on fuel cladding. - Abstract: This research examines the concentration of radiolysis species (H_2, O_2, and H_2O_2) over the porous crud layer using a three dimensional time dependent solute transport model. A Monte Carlo random walk technique is adopted to simulate the transport behavior of the different species with various parametric studies of source term, crud thickness, and crud porosity. Particularly, this model employs a system of coupled mass transport and chemical interactions as the source term, which makes the problem non-linear. It is demonstrated that a negligible effect on radiolysis species concentrations change due to the consideration of source term. The crud thickness and porosity effect on the concentration distributions are notably observed. In general, higher concentration starts from the intersection of the heating surface with the chimney wall from the beginning and it reaches the equilibrium state within tens of seconds. The concentration profiles of the radiolysis species H_2, O_2, and H_2O_2 can be directly related to corrosion issues. The direct application of this study to nuclear engineering research is to aid in the design of reactors with higher performance without experiencing an Axial Offset Anomaly (AOA), an unexpected measured shift in axial power distribution from predicted values.
[en] To increase the production of RI and labelled compounds utilizing the Korea Multipurpose Research Reactor (KMRR), development of P-32 production process, devices and tools of neutron irradiation use, GMP facilities of radiopharmaceuticals, Dy-165/Ho-166 macroaggregate of radiation synovectomy use for rheumatoid archritis have been carried out, respectively. To utilize NAA in analysis of environmental samples, experimental studies on air borne samples have also been carried out. An efficient P-32 production process obtaining high recovery of >98% with sufficiently high radionuclidic purity of >99% has been established through reaction 32S(n,p)32P and subsequent reduced pressure distillation purification. Various capsules, loading/unloading device for capsule/rigs, cole-welder for capsules, checking instrument for capsule sealing, working table/tools, transfer cask for the irradiated targets, etc. have been developed. To maintain cleanliness inside of hot cells, a modification has been proposed, and a two door type autoclave usable in GMP facility has been prepared. An efficient way of preparation of the Dy-165/Ho-166 macroaggregate of radiation synovectomy use as well as its clinical application scheme has been developed. A suitable process of environmental sample analyses has been established by carrying out NAA of standard/reference samples as well as airborne dust samples. (Author)
[en] Highlights: • Experimental head loss testing was conducted by aggressively promoting corrosion in loss of coolant accidents. • Blender-processed debris beds have higher head loss but tend to be less reproducible than NEI-processed debris beds. • Precipitation was observed from aluminum concentration and turbidity measurements. • Precipitation results were compared to predictions from Visual MINTEQ. - Abstract: This paper presents the results of an integrated chemical effects experiment of head loss across the sump pump screen with fibrous debris bed over a non-prototypical 10-day post-LOCA incident window. The corrosion head loss experiments (CHLE) is a reduced scaled integral effects testing facility built at the University of New Mexico (UNM) to investigate potential chemical effects on head loss across prepared fibrous debris beds. The results in this paper come from two integral effect tests performed at UNM in order to determine the chemical effects on head loss induced by a zinc source effect and an aluminum precipitation effect (T3: without Zn source case, T4: with Zn source case in containment). The tests were performed with a large surface area of aluminum coupons in the testing facility for an extended period of elevated temperature to accelerate corrosion above that expected under prototypical conditions. These conditions were sufficient to force aluminum precipitation to occur and induce the onset of chemical effects on debris bed head loss. The head loss behavior on two different types of fiber debris beds (blender-processed and NEI-processed debris bed) was evaluated in this study. It was found that the blender-processed bed is much more sensitive in filtering than the NEI-processed bed and consequently had a much higher head loss value across the beds. Aluminum precipitation was observed, with aluminum concentration and turbidity measurements, to form starting on day 7 in Test T3 and on day 6 in Test T4. The onset of aluminum precipitation-induced head loss increase was observed in a similar time frame in both CHLE T3 and T4 tests. In addition, the results of surface analysis (XPS, SEM-EDS) for the tested fiberglass bed are presented