XUV-FEL spectroscopy; He two-photon ionization cross-sections

Sato, Takahiro*; Iwasaki, Atsushi*; Ishibashi, Kazuki*; Okino, Tomoya*; Yamanouchi, Kaoru*; Adachi, Junichi*; Yagishita, Akira*; Yazawa, Hiroki*; Kannari, Fumihiko*; Aoyama, Makoto; et al.

Europhysics News, 42(5), P. 10, 2011/09

The resonant and non-resonant two-photon single ionization processes of He were investigated using intense free electron laser light in the extreme ultraviolet (XUV) region (53.4-61.4 nm) covering the 1s-2p and 1s-3p resonant transitions of He. On the basis of the dependences of the yield of He on the XUV light-field intensity at 53.4, 58.4, 56.0 and 61.4 nm, the absolute values of the two-photon ionization cross sections of He at the four different wavelengths and their dependence on the light-field intensity were determined for the first time.

Irradiation history of Itokawa regolith material deduced from noble gases in the Hayabusa samples

Nagao, Keisuke*; Okazaki, Ryuji*; Nakamura, Tomoki*; Miura, Yayoi*; Osawa, Takahito; Bajo, Kenichi*; Matsuda, Shintaro*; Ebihara, Mitsuru*; Ireland, T.*; Kitajima, Fumio*; et al.

Science, 333(6046), p.1128 - 1131, 2011/08

https://doi.org/10.1126/science.1207785

A steroid surface materials record regolith processes and a history of cosmic-ray irradiation. Noble gas isotopes in three rocky grains from Itokawa have been determined. High concentrations of solar He, Ne, and Ar, as high as those in lunar soils, are released at variable temperatures from each sample. The isotopic compositions are essentially identical to those of solar wind but distinguishable in He relative abundance. These noble gas characteristics can be explained by repeated implantation and preferential loss of solar He by removal of weathered He-rich rim on the grain surface through friction among regolith grains on Itokawa. Residence time of regolith materials on Itokawa is alculated to be shorter than 10 Myr, suggesting that regolith materials of small asteroids would escape easily to space.

Development of 3-D detailed FBR core calculation method based on method of characteristics

Takeda, Toshikazu*; Imai, Hideki*; Kitada, Takanori*; Nishi, Hiroshi; Ishibashi, Junichi; Kitano, Akihiro

Proceedings of International Topical Meeting on Mathematics and Computation, Supercomputing, Reactor Physics and Nuclear and Biological Applications (M&C 2005) (CD-ROM), 12 Pages, 2005/09

A new detailed 3-D transport calculation method taking into account the heterogeneity of fuel assemblies has been developed in hexagonal-z geometry by combining the method of characteristics and the nodal transport method. From the nodal transport calculation which uses assembly homogenized cross sections, the axial leakage is calculated, and it is used for the MOC calculation which treats the heterogeneity of fuel assemblies. Series of homogeneous MOC calculations which use assembly homogeneous cross sections are carried out of obtain effective cross sections, which preserve assembly reaction rates. This effective cross sections are again used in the 3-D nodal transport calculations. The numerical calculations have been performed to verify 3-D radial calculations of FBR assemblies and partial core calculations. Results are compared with the reference Monte-Carlo calculations. A good agreement has been achieved. It is shown that the present method has an advantage in calculating reaction tates in small region.

High power millimeter and submillimeter wave material processing

Mitsudo, Seitaro*; Hoshizuki, Hisanori*; Matsuura, Kazunari*; Saji, T.*; Idehara, Toshitaka*; Glyavin, M.*; Eremeev, A.*; Zapevalov, V.*; Kitano, Akihiro; Nishi, Hiroshi; et al.

Proceedings of 29th International Conference on Infrared and Millimeter Waves (IRMMW 2004)/12th International Conference on Terahertz Electronics (THz 2004), p.727 - 728 , 2004/09

Boron carbide (BC) is one of advanced materials and is being used in a wide rage of applications. The unique feature of this material is its large neutron-absorbing cross-section. Some of its most prominent applications are controlling rods in nuclear reactors and radiation protection. 24 GHz microwave processing for BC ceramics were performed under flowing argon gas using the sintering system. The sintered samples were characterized by the density, the shrinkage and SEM micrographs of fracture surface. Above the temperature of 2000C, the shrinkage and the grain grows were observed.

Transport Criticality Analysis for FBR MONJU Initial Critical Core in Whole Core Simulation by NSHEX and GMVP

Galina Todorova; Nishi, Hiroshi*; Ishibashi, Junichi

Saikuru Kiko Giho, (22), p.1 - 10, 2004/00

https://rdreview.jaea.go.jp/gihou/pdf2/n22-01.pdf

FBR MONJU Initial Critical Core (ICC) criticality problem has been solved by deterministic and Monte Carlo transport methods by the codes NSHEX and GMVP. The analysis has been carried out in different energy-groups approximations. As a result the effect of cross-section (XS) condensation from 70 into few energy-group structures by different collapsing methods has been evaluated. The 3D discrete-ordinate code NSHEX has been applied for wide range of core simulations-from whole core, considering the fissile, fertile and shielding regions to simplified models that simulate an increased neutron leakage. It has been found that there is room for improvement in the assessment of the neutron leakage in the few energy-group approximations. The good agreement between NSHEX and GMVP results, especially without XS collapsing, is pointed out as a conformation for the applicability of the code NSHEX in FBR 3D whole core calculations. Some practical conclusions have been extracted that are important

Improvements of the Control Rod Material for Long Lifetime by the High Power Millimeter-wave Ceramics Sintering Method

Idehara, Toshitaka*; Mitsudo, Seitaro*; Hoshizuki, Hisanori*; Ogawa, Isamu*; Shibahara, Itaru; Nishi, Hiroshi; Kitano, Akihiro; Ishibashi, Junichi

JNC TY4400 2003-005, 106 Pages, 2003/03

JNC-TY4400-2003-005.pdf:9.48MB

Boron Carbide B4C pellet is an important part of control rod used to control the reactivity of nuclear reactors. B4C pellet put in a nuclear reactor suffers heavy radiation damage and deformation, which result in a partial destruction and shorten the lifetime of B4C. It is important to improve the characteristics of the B4C pellets for extension of its lifetime. As the results, if the control rod without the shroud will be available, we can realize much simpler structure. In order to improve, the B4C pellet, which was sintered by the hot-press methods, we have re-sintered it by high power millimeter wave ceramics nano-indentation test. The increase of the plasticity is observed. The same improvement of plasticity was observed in alumina pellets that were sintered by millimeter wave sintering methods. Such results imply that the further improvement is expected, if the B4C pellet is sintered from powder specimen by the high power millimeter-wave sintering method. To simulate a partial destruction of B4C pellet under the thermal stress, preliminary internal heating experiments of B4C pellet are performed by using high power millimeter-wave. At the difference between internal and surface temperatures of 1000C, the partial destructions and small cracks are observed in B4C pellet. Thes may be a kind of model experiment for destruction of B4C pellet irradiated by neutrons.

BC ceramics sintering using 24 GHz gyrotron radiation

Hoshizuki, Hisanori*; Kuroda, Tsutomu*; Mitsudo, Seitaro*; Idehara, Toshitaka*; Glyavin, M.*; Kitano, Akihiro; Ishibashi, Junichi; Nishi, Hiroshi; Shibahara, Itaru

En Sekigai Ryoiki Kaihatsu Kenkyu, 4, p.179 - 185, 2003/00

https://karin21.flib.u-fukui.ac.jp/repo/TD00005582

None

Millimeter wave sintering of BC by using a compact gyrotron system

Hoshizuki, Hisanori*; Mitsudo, Seitaro*; Glyavin, M.*; Eremeev, A.*; *; Iwai, Yoshiro*; Kitano, Akihiro; Ishibashi, Junichi; Nishi, Hiroshi; Shibahara, Itaru; et al.

Proceedings of 28th International Conference on Infrared and Millimeter Waves (IRMMW 2003), P. 1005, 2003/00

None

A Study on cell heterogeneity effects in the MONJU core; Evaluation using the continuous energy Monte Carlo code MVP

Morohashi, Yuko; Ishibashi, Junichi;

JNC TN4400 2001-003, 28 Pages, 2002/03

JNC-TN4400-2001-003.pdf:1.12MB

The criticality analysis of the MONJU initial critical core was conducted based on conventional methods developed by the JUPITER program. Effective cross sections were created, considering self-shielding effects, from the JAERI Fast Set (JFS-3-J3.2); group constants in 70 energy groups, which were processed from the Japanese Evaluated Nuclear Data Library (JENDL-3.2). These were used in the standard calculation method: a 3-Dimensional Hexagonal-Z whole core calculation by diffusion theory. This standard calculation, however, involves several approximations. The continuous neutron energy spectrum is divided into 70 discrete energy groups and continuous spatial coordinates are represented by assembly-wise spatial meshes. Original transport equations are solved by diffusion theory (isotropic scattering) approximation and fine structures in fuel assemblies, such as fuel pins or wrapper tubes, are processed into cell-wise homogeneous mixture. To improve the accuracy of the results, these approximations are compensated for by applying corresponding correction factors. Cell heterogeneity effects, among them, were evaluated to be 0.3-0.4% k/kk' by diffusion calculations based on the group constants, obtained by heterogeneous cell model calculations. This method, however, has the drawback that it assumes that there is no interdependency of the related approximations; energy grouping, diffusion approximation, etc. A study on cell heterogeneity effects has been conducted using the continuous energy Monte Carlo method to validate the adequacy of this non-interdependency assumption. As a result, cell heterogeneity effects slightly larger than those from conventional methods have been obtained; 0.54% k/kk' for the initial critical core, and 0.50% k/kk' for the initial full power core. Dependency on plutonium enrichment and fuel temperature has also been identified, which implies the dependency of the cell heterogeneity effects on the specific ...

Hydrochemical analyses to evaluate groundwater system in Horonobe Area, Hokkaido, Japan

Sakai, Ryutaro; Munakata, Masahiro; Seguchi, Mariko*; Ooka, Masao*; Ichikawa, Yasuo*; Nakamura, Masaru*; Ishibashi, Junichiro*

no journal, , 

In the safety assessment for a geological disposal of radioactive waste, it is important to establish validation methods for deep groundwater flow system to estimate radionuclide migration to human environment through groundwater flow. This study discussed the method which estimates groundwater mixing condition and groundwater flow process using principal component analysis to groundwater chemistry and isotopic compositions in case of Horonobe area. The results demonstrated that there are three component of deep groundwater which has long residence time and surface water derived from meteoric water in this area.