Proposal of Integrated Test Facility for in-Vessel Thermofluid Safety of Fusion Reactors

A vacuum vessel (VV) of a tokamak fusion reactor like the International Thermonuclear Experimental Reactor (ITER) consists the first confinement barrier that includes the largest amount of radioactive materials such as tritium and activation products. The ingress of coolant event (ICE) is a design basis event in the ITER where water is used as the coolant. The loss of vacuum event (LOVA) is also considered as an independent design basis event. Based on the results of ICE and LOVA preliminary experiments, an integrated in-vessel thermofluid test is being planned and conceptual design of the facility is in progress. The main objectives of the integrated test are to investigate the consequences of possible interaction of the ICE and the LOVA and to validate the analytical model of thermofluid events in the VV of the fusion reactor. This paper introduces a conceptual design of the integrated test facility and a testing plan.     

Performance of a 3000/6000 V, 1000 kVA class superconducting transformer developed for a prospective power transmission model system integrated under superconducting environment (PROMISE)

A 3000/6000V, 1000 kVA class superconducting transformer (SC-Tr) was developed for a Prospective Power Transmission Model System Integrated under Superconducting Environment (PROMISE). In this transformer, the core and superconducting windings are immersed in liquid helium and the major insulation is provided by the liquid helium. This paper describes both the design features and measured characteristics of the SC-Tr. Fundamental characteristics of the SC-Tr are obtained through no-load, short-circuit tests and quench experiments. The results of the no-load test have verified that the SC-Tr has the capability to withstand ac voltage of 3000/6000 V of 60 Hz without any partial discharge. The short-circuit tests have proved that the SC-Tr is capable of carrying ac current of 170 Arms without quench in the superconducting windings. Furthermore, in a real-load experiment with the PROMISE, electric power of 3800 V-460 kVA of 50 Hz in high-voltage side is transmitted through this SC-Tr.     

A novel approach to deliverable power in low‐voltage DC distribution system on the basis of voltage stability

This paper proposes that a deliverable power through a low‐voltage DC distribution system has an upper limitation. The upper limitation of the deliverable power, P_lim, is explained on the basis of a voltage instability phenomenon occurring for the load with a voltage sensitivity below 1. From theoretical‐calculation results, it is pointed out that P_lim diminishes with augment in the distribution‐line length. This phenomenon becomes more distinct for the higher distribution‐line inductance per unit length. Connection of the capacitor to the receiving end of the distribution line is discussed as a method for rising P_lim. Measurements of the voltage waveform at the load terminals successfully support P_lim derived from the theoretical calculation. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Deliverable‐power dependence on distribution‐line resistance and number of loads in low‐voltage DC distribution system

In this paper, we show that in a low‐voltage DC distribution system the deliverable power to a load has an upper limit P_lim due to the voltage instability at the receiving ends. On the basis of the previously derived concept of P_lim, we obtain the dependence of P_lim on the distribution line resistance R. In addition, we investigate the influence of the number of loads on P_lim. The result shows that a distribution line of lower R causes P_lim to be lower. This reduction in P_lim becomes more distinct for a larger number of loads. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Risk assessment for optimum low‐voltage distribution facilities constructed by using genetic algorithms

The influences of uncertainty of the load growth rate and interest rate on the total cost of low‐voltage distribution facilities was investigated. We assumed that the total cost was composed of the initial construction cost, the improvement cost, and the cost of power loss. We also assumed that the distribution facilities were operated for 30 years. Genetic algorithms were used to determine how to construct cost‐effective distribution facilities that did not compromise power quality. Two investment methods were compared: one in which the utility cut down the initial construction cost and improves the initial facilities along with the load growth, and one in which the utility bears the large initial cost without the improvement cost. It was found that the lower cost method depends on the load growth rate and the interest rate. It was also found that the influence of uncertainty in the load growth rate increases with an increase in the differential between the actual load growth rate and the expected one. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 172(2): 10–19, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20976     

p27 Is a Critical Prognostic Biomarker in Non-Alcoholic Steatohepatitis-Related Hepatocellular Carcinoma

Non-alcoholic steatohepatitis (NASH) is a recently identified chronic liver disease, which progresses to liver cirrhosis and hepatocellular carcinoma (HCC). As the number of patients studied to date has been limited, clinically useful prognostic biomarkers of NASH-related HCC have not been available. In this study, we investigated the status of a cell-cycle regulator, p27, in NASH-related HCC. p27 has been regarded as a prognostic factor in various types of cancer patients. A total of 22 cases with NASH-related HCC were analyzed for p27 protein expression, and phosphorylation at threonine 157 (T157) and serine 10 (S10) by immunohistochemical analysis. The correlation of p27 with tumor characteristics, disease-free survival (DFS), and overall survival was analyzed. p27 expression was decreased in 13 HCCs (59%), and was significantly correlated with enlarged tumor size (p = 0.01) and increased cell proliferation (p < 0.01). Phospho-p27 at T157 and S10 was detected in four (18%) and seven (32%) cases, respectively, and patients positive for phospho-p27 (S10) showed reduced DFS (hazard ratio 7.623, p = 0.016) by univariate analysis. Further studies with more patients are required to verify the usefulness of p27 as a biomarker for predicting tumor recurrence in NASH patients.     

Acidity of β zeolite with different Si/Al2 ratio as measured by temperature programmed desorption of ammonia

High quality β zeolite (BEA) with a Si/Al₂ ratio of 30:70 was readily prepared by a dry gel conversion method. Acidity of the thus prepared β zeolite was measured by an improved technique of temperature programmed desorption of ammonia. Concentration of acid site, measured from the desorbed ammonia, was nearly equal to that of aluminum in the zeolite, and the enthalpy change of ammonia desorption, i.e., the strength of acidity, was 124–127 kJ mol⁻¹, and independent of the concentration of acid site. The long tailing desorption of ammonia was distinct at higher temperature, and this was characteristic of BEA. The tail-like desorption spectrum may be correlated with the presence of strong acid site due to the defect or the tetrahedral site with different structural environments; the conclusion was supported by the characterization data using NMR, IR, and test reaction. Thus found solid acidity was compared with that of the commercially available β zeolite; the observed small difference was explained due to the presence of extra-framework Al.     

Distribution voltage rise at dense photovoltaic generation area and its suppression by SVC

An SVC is proposed as a reactive power compensation device to suppress the rise in the customer voltage due to photovoltaic power generation systems. The SVC produces a reactive power by controlling a thyristor. The effect of the SVC on the rise in the customer voltage has been investigated. Calculation results show that installing an SVC on the low‐voltage side is more effective for suppressing the rise in the customer voltage compared to an SVC located on the high‐voltage side. As far as the calculation conditions are concerned, it is found that the rated capacity of the SVC needed to maintain the customer voltage within 101±6V is over ±11.1kVA. The slope reactance required to suppress the customer voltage lower than 107 V is found to be under 1.28%. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(2): 47–53, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20478     

Soft Decision with Soft Target for Car-like Mobile Vehicle in Dynamic Environment

Online flexible operation of a car-like mobile vehicle with non-holonomic constraints in dynamic environment is still a very challenging problem because the surrounding situations are not qualified in static, knowledge is only partial and the execution is often associated with uncertainty. The difficulty lies in the setting of appropriate moving sub-targets in real-time to obtain a collision-free and low-cost path. In this paper, we present a new approach for the autonomous motion control of mobile vehicle in a narrow area with static and dynamic obstacles. It is based on the selection of sub-target points of vehicle's movement called ‘soft target’ which is a target set defined as all possible and reachable via-points in a navigation space. The soft target is acquired by online learning based on the final target and environment information. Each element of it has its membership value in [0, 1] denoting its evaluation degree. With the acquired soft target, soft decision is made like human's decision process by predictive fuzzy control (PFC) to achieve final target safely and economically. The simulation results show the effectiveness and flexibility of the proposed vehicle motion control method. © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Increase of inductance ratio of flat type fault current limiter with high‐Tc superconducting disk

Fault current limiters (FCLs) are expected to reduce fault current and improve stability of power systems. A flat type fault current limiter consisting of the pancake primary winding and a high‐T_c superconducting (HTS) disk was proposed as a modified version of a conventional magnetic shield type of the FCL with the superconducting cylinder. The flat type FCL has the advantage of being manufactured smaller than the cylinder type FCL. It is pointed out, from a magnetic field analysis, that the volume of the flat type FCL is smaller than that of the cylinder type FCL with same magnitude of the limiting inductance. Further, the magnetic field analysis suggests that a high inductance ratio can be realized by radially enlarging both the primary winding and the HTS disk, stacking the FCL modules in layers and sandwiching the primary winding with superconducting disks. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.