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We demonstrated photonic band characterization in photonic crystals (PhCs) based on InGaN/GaN nanocolumn (NC) arrays fabricated by Ti-mask selective area growth. Triangular and honeycomb latticed NCs with approximately the same diameter and closest distance were successfully fabricated. To effectively observe the photonic bands, we designed an angle-resolved micro-photoluminescence measurement system. The photonic bands in the honeycomb lattice were at longer wavelengths compared with those in the triangular lattice, indicating that, for the honeycomb lattice, narrower NCs were available to realize PhC effects in the long-wavelength region. Therefore, narrow honeycomb lattices with large nanocrystalline and PhC effects are suitable for long-wavelength emission.

The hydrogen treatment system has been developed in order to prevent the overpressure of the primary containment vessel (PCV) caused by a large amount of hydrogen generated by the metal-water reaction in severe accidents (SAs) of Light Water Reactor. In previous studies, we evaluated the hydrogen treatment rate using a couple of metal oxides, and confirmed that MnO2, CuO, and Co3O4 were effective for the hydrogen oxidation under the oxygen-free condition, then we selected them as reactants[1]. Although the reactants were granulated with a diameter of 2 mm for application to the system, the hydrogen treatment rate has not been scarcely evaluated for the granulated MnO2 which is expected to treat the hydrogen around 120 °C [2]. Thus, we made the diameter of the granulated MnO2 smaller, and found that the hydrogen treatment was occurred by the granulated MnO2 with a diameter below 1.0 mm. The granules with a diameter below 1.0 mm were also acceptable for the system from the point of view of decreasing the differential pressure (DP). Moreover, the experiments using a test section simulating a reactor of the system had been conducted under the hydrogen condition simulating typical condition of a SA, by loading the granulated CuO with a diameter of 2mm onto the granulated MnO2 with a diameter of 1mm. As a result, the hydrogen treatment was markedly accelerated by supplying enough reaction heat from the granulated MnO2 to the granulated CuO.

At the Tokyo Institute of Technology (TIT) a fourvane RFQ is to be applied for inertial confinement fusion research [l]. The RFQ (TIT RFQ) is designed for acceleration of paIticles with charge to mass ratio (q/A) of 1/16 from 5keV/amu to 21 3keV/amu. The planned maximum injection beam current is lOmA for l6O+. Beam dynamics was calculated using a PIC (Particle-In-Cell) code which can take influence of the multipole components in the intervane potential into account. For input beam current of 1 OmA transmission of 60% was obtained.A half-scaled cold model was fabricated to investigate fundamental rf characteristics. In the cold model experiment, the difference in electric field strength between each quadrant was minimized to fi% by using side tuners and flat field distribution along the beam axis was achieved by adjusting end tuners.In a previous paper[l] a design of the TIT RFQ with the vane-tip curvature radius of 0.75, was presented. The computer code PARMTEQ was used to simulate the beam dynamics in the RFQ and the computer code GENRFQ was used to generate the vane parameters for PARMTEQ calculation. For this old design the beam transmission was expected to be 72% for the injection current of 10mA.In the meantime, one of the authors of this paper developed a new simulation code "QLASSI (Quadrupole Linear Acceleration Simulator with Space and Image charge effect)"[2] which can simulate the beam dynamics including influence of the multipole components in the intervane potential. This code was applied to calculation of the beam dynamics for the old design. Since the result of this calculation showed very poor transmission efficiency of 3496, the TIT RFQ had to be redesigned.In this paper we describe the modifications of vanetip design as well as the cavity geometry, which are necessary to improve the beam dynamical performance. The beam transmission pehormance for the new design is presented. Recent results on a half-scaled model including development of tuning device are also reported. NEW SIMULATION CODE QLASSIIn computer code QLASSI, the equation of motion in the RFQ is expressed as where U$q, U,, and Vi, are the external RFQ potential, the space charge potential and the image charge potential, respectively. In the calculation, eq.(l) is numerically integrated for each particle using fourth-order RungeKutta method. Harmonics up to the dodecapole moment are taken into account in Ugq. U,, is given by the sum of monopole Coulomb potential from all other particles. Uic is determined by solving a 3D Dirichlet's boundary problem defined by the beam space charge and the metallic electrode surface. Figure 1 shows axial transmission profile calculated using QLASSI for the old design. For the injection beam current of lOmA the transmission is only 3496, which is less than half of the one calculated using PARMTEQ. NEW DESIGN OF THE TIT RFQThe TIT RFQ was redesigned since the predicted transmission was limited to 34%. In the new design the curvature radius of vane-tip was increased from 0.75, to ro in order to suppress th...

TiO 2 addition into boiling water reactor (BWR) primary system is being developed as a method to mitigate stress corrosion cracking (SCC) of the BWR structural materials. This technique aims for electrochemical corrosion potential (ECP) decrease of reactor materials by photo-excitation reaction under Cherenkov irradiation. Tests have been conducted in the test loop in both BWR and OECD Halden reactor to investigate the feasibility of the SCC mitigation method with TiO 2 . The test results showed that the ECP of TiO 2 deposited materials was decreased to <-0.3V(vs.SHE) under both UV light irradiation in the BWR reactor water normal water chemistry (NWC) environment and in-core Cherenkov irradiation in the Halden BWR simulation loop under higher dissolved oxygen condition. This TiO 2 technique was confirmed to be feasible as a SCC mitigation method for BWR structural materials.