Radiation Safety Considerations for LHD Experiments

For experiments with the Large Helical Device (LHD) which is now under construction at the Toki site in Japan, radiation safety issues were discussed. In the course of plasma experiments, radiations such as X-rays, induced -rays, and neutrons increase. From a safety point of view, these radiation exposures to the environment should be controlled to limit the annual dose to less than 50 Sv at the site boundary. In order to meet this, an area monitoring system named RMSAFE (Radiation Monitoring System Applicable to Fusion Experiments) has been developed and partly installed. This can discriminate and measure radiations including burst-like emissions due to plasma shots from natural radiations. For the present period, this system is operating to monitor the natural radiation levels before the LHD operation. It was observed that the radiation levels strongly depend on rain levels and ground state. An indoor area monitoring system has already been implemented on site, to measure radiations from NBI and ECH test shots, and it shows good monitoring ability. Also, thermoluminescence dosimetry has been applied. The importance of investigating the radiological behavior under natural conditions with continuous monitoring is shown.     

Reirradiation therapy for brain metastases from small cell lung cancer

Several evidences support the hypothesis that central catecholamines may play a significant role in the production and/or maintenance of different alterations that characterize portal hypertension. The aim of the present work was to study the possible modifications in norepinephrine (NE) metabolism in several telencephalic and diencephalic areas rich in NE in experimental prehepatic portal hypertension. NE uptake was studied as an index of NE metabolism. The experiments were carried out in vitro in encephalic areas and nuclei, obtained according to the punch-out technique. Results indicated that portal hypertensive rats showed an enhancement of NE uptake in olfactory bulb (OB), preoptic area (PA), and supraoptic, periventricular, paraventricular, and arcuate nuclei (SON, PeVN, PaVN, and AN, respectively) compared to sham-operated rats. However, no modifications on NE uptake was observed in the median eminence (ME). Present results suggest that the changes observed in central NE uptake may be related to the development and/or maintenance of the portal hypertensive state.     

Molecular weight dependency of refractive index increment of polystyrene determined by uniform oligomers

Molecular weight dependency of a specific UV absorption coefficient of polystyrene in solution was determined by supercritical fluid chromatography applied to equimolar and equimass mixtures of uniform polystyrenes whose degree of polymerization was n = 1 to 40. From the ratio between the response from a UV detector and that from a refractometer, we determined the refractive index increment dn/dc as a function of molecular weight for polystyrene in tetrahydrofuran at the wavelength λ = 633 nm. We found that dn/dc is well expressed as a linear function of the reciprocal of molecular weight for uniform polystyrenes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1101–1106, 2004     

Role of ADS in the back-end of the fuel cycle strategies and associated design activities: The case of Japan

Reduction of burden caused by radioactive waste management is one of the most critical issues for the sustainable utilization of nuclear power. The Partitioning and Transmutation (P&T) technology provides the possibility to reduce the amount of the radiotoxic inventory of the high-level radioactive waste (HLW) dramatically and to extend the repository capacity. The accelerator-driven system (ADS) is regarded as a powerful tool to effectively transmute minor actinides (MAs) in the “double-strata” fuel cycle strategy. The ADS has a potential to flexibly manage MA in the transient phase from light water reactors (LWRs) to fast breeder reactors (FBRs), and can co-exist with FBR symbiotically and complementarily to enhance the reliability and the safety of the commercial FBR cycle. The concept of ADS in JAEA is a lead-bismuth eutectic (LBE) cooled, tank-type subcritical reactor with the power of 800 MWth driven by a 30 MW superconducting LINAC. By such an ADS, 250 kg of MA can be transmuted annually, which corresponds to the amount of MA produced in 10 units of LWR with 1 GWe. The design study was performed mainly for the subcritical reactor and the spallation target with a beam window. In Japan, Atomic Energy Commission (AEC) has implemented the check and review (C&R) on P&T technology from 2008 to 2009. In the C&R, the benefit of P&T technology, the current status of the R&D, and the way forward to promote it were discussed.     

Composite nonwoven separator for lithium-ion battery: Development and characterization

A new type composite nonwoven separator has been developed by combining a polyacrylonitrile (PAN) nano-fiber nonwoven and ceramic containing polyolefin nonwoven. The physical, electrochemical and thermal properties of the separator were investigated. The separator has mean pore size of about 0.8 μm as well as narrow pore-size distribution. Besides, the separator possesses higher porosity and air permeability than a conventional microporous membrane separator. The separator showed tensile strength of 46 N 5 cm⁻¹ at 10% elongation. Any internal short circuit was not observed for cells with the separator during charge-discharge test, and the cells showed stable cycling performance. Moreover, the cells showed better rate capabilities than cells with the conventional one. On a hot oven test at 150 °C, the composite nonwoven separator showed better thermal stability than the conventional one. In addition, internal short circuit by thermal shrinkage of separator was not observed for a cell with the separator at 150 °C for 1 h.     

Velocity vector profile measurement using multiple ultrasonic transducers

This paper proposes a new technique that enables the measurement of the velocity vector in multi-dimensions on a line of the flow field. A system to achieve this goal was developed based on the ultrasonic velocity profiling by using multiple transducers. A two-dimensional system was constructed and successfully applied to an actual flow field for two-dimensional velocity vector measurements. To estimate the influence of the existence of a wall, acoustic field under the developed system was calculated by solving two-dimensional wave equation and then the focal point of an ultrasonic beam was determined to optimize the system. The system was applied to measure the two-directional velocity components of a periodic velocity fluctuation in the wake of a cylinder as an example of unsteady flow. Temporal variation of velocity vector profiles well represent the velocity fluctuation, and vorticity distribution, which is obtained from the spatial distribution of velocity vector, well represents the vertical motion in the wake.     

C60 Nanowhiskers in a Mixture of Lead Zirconate Titanate Sol–C60 Toluene Solution

Fine fibrous structures of C₆₀ with a diameter on the order of nanometers were discovered in a lead zirconate titanate sol ultrasonically mixed with a toluene solution of C₆₀. By transmission electron microscopy observations, they were identified as single-crystalline fibers of C₆₀ with submicrometer diameters, i.e., nanowhiskers of C₆₀. The C₆₀ nanowhiskers showed thin slablike TEM images, and the growth axis of the nanowhiskers was parallel to the 〈110〉 close-packed direction of a fcc crystal system of C₆₀.     

High prevalence of mitochondrial diabetes mellitus in Japanese patients with major risk factors

To identify diabetes mellitus caused by the mitochondrial gene substitution at genomic nucleotide pair 3243 (M3243A-->G) we selected 87 diabetic patients with high risk factors such as maternal inheritance and hearing loss. Total DNA was extracted from peripheral leukocytes, and mitochondrial DNA fragments containing M3243A-->G were amplified by polymerase chain reaction (PCR). The amplified fragments were digested with a restriction endonuclease Apa1 and analyzed by agarose gel electrophoresis. The incidence of the M3243A-->G mutation was 4.6% (four of 87) in diabetic patients with maternal inheritance and/or hearing loss. In a subgroup with both maternal inheritance and hearing loss, the incidence of the mutation was as high as 21.4% (three of 14). Cardiac disorders were also present in all four diabetic patients with the mutation. This study suggests that maternal inheritance and hearing loss are useful clinical findings to identify diabetic patients with the mutation, and that cardiac involvement is a high risk factor for the M3243A-->G mutation.     

A reinforcement learning method based on an immune network adapted to a semi-Markov decision process

The immune system is attracting attention as a new biological information processing-type paradigm. It is a large-scale system equipped with a complicated biological defense function. It has functions of memory and learning that use interactions such as stimulus and suppression between immune cells. In this article, we propose and construct a reinforcement learning method based on an immune network adapted to a semi-Markov decision process (SMDP). We show that the proposed method is capable of dealing with a problem which is modeled as a SMDP environment through computer simulation. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008