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Hirooka, Shun; Horii, Yuta; Sunaoshi, Takeo*; Uno, Hiroki*; Yamada, Tadahisa*; Vauchy, R.; Hayashizaki, Kohei; Nakamichi, Shinya; Murakami, Tatsutoshi; Kato, Masato
Journal of Nuclear Science and Technology, 60(11), p.1313 - 1323, 2023/11
Times Cited Count：5 Percentile：78.63(Nuclear Science & Technology)Additive MOX pellets are fabricated by a conventional dry powder metallurgy method. Nd
O
and SmO are chosen as the additive materials to simulate the corresponding soluble fission products dispersed in MOX. Shrinkage curves of the MOX pellets are obtained by dilatometry, which reveal that the sintering temperature is shifted toward a value higher than that of the respective regular MOX. The additives, however, promote grain growth and densification, which can be explained by the effect of oxidized uranium cations covering to a pentavalent state. Ceramography reveals large agglomerates after sintering, and Electron Probe Micro-Analysis confirms that inhomogeneous elemental distribution, whereas XRD reveals a single face-centered cubic phase. Finally, by grinding and re-sintering the specimens, the cation distribution homogeneity is significantly improved, which can simulate spent nuclear fuels with soluble fission products.
Nakashio, Nobuyuki*; Osugi, Takeshi; Kurosawa, Shigenobu; Ishikawa, Joji; Hemmi, Ko; Iketani, Shotaro; Yokobori, Tomohiko
JAEA-Technology 2022-016, 47 Pages, 2022/08
JAEA-Technology-2022-016.pdf:2.23MB
The Nuclear Science Research Institute (NSRI) of the Japan Atomic Energy Agency (JAEA) started operation of the Advanced Volume Reduction Facilities (AVWF) for production of waste packages for disposal of low-level radioactive solid wastes (LLW). To clarify the operating conditions for homogenization of non-metallic LLW, preliminary tests were carried out using the plasma melting furnace of the non-metal melting unit. The fluidity of molten waste influences homogenization conditions of solidified products. It was clarified that the viscosity, which is determined by the chemical composition and the melting temperature, influence the fluidity of molten waste greatly through previous literature review and the small-scale melting tests. In the preliminary tests, the simulated waste with a cold tracer loaded in 200 L drums were melted. Using the waste chemical components (basicity, iron oxide concentration) as an experimental parameter, the homogeneity of the chemical components of the solidified product was investigated and the homogenization conditions of melting tests were examined. The retention ratio of the tracer in the molten bath was also confirmed. The viscosity of the molten wastes was measured and the correlation with homogeneity was examined. In addition, the technical requirements that should be concerned in advance for future actual operation were discussed.
Maruyama, Shuhei
Proceedings of International Conference on Physics of Reactors 2022 (PHYSOR 2022) (Internet), 10 Pages, 2022/05
This paper proposes a new homogenization method, "Boundary Condition Free Homogenization (BCFH)". The traditional homogenization method separates the core calculation and the cell (assembly) calculation by assuming a specific boundary condition or a peripheral region in the cell calculation. Nevertheless, there are ambiguities and approximation in these assumptions, and they can also cause a decline in accuracy. BCFH aims to avoid these problems and improve the accuracy in the cell calculation such as homogenization. We imposed the conditions that the physical quantities in the cell related to the reaction rate preservation is preserved for any incoming partial current, during the homogenization. That is, the response matrices of cell average (or total) flux and outgoing partial current, to be the same form between heterogeneous and homogeneous system. As a result, homogenized parameters, such as cross-sections, superhomgenization factors, and discontinuity factors, are no longer dependent on a specific boundary condition. The new homogenized parameters obtained in this way are extended from the conventional vector form to the matrix form in BCFH. To investigate the performance of BCFH, numerical tests are done for the simplified models which originates in 750MW-class sodium-cooled fast reactor with MOX fuel core in Japan. It is found that BCFH is particularly effective in evaluating control rod reactivity worth and reaction rate distribution, compared to the traditional method. We conclude that the BCFH can be a promising homogenization concept for core neutronic analysis.
Takino, Kazuo; Sugino, Kazuteru; Oki, Shigeo
Annals of Nuclear Energy, 162, p.108454_1 - 108454_7, 2021/11
Times Cited Count：1 Percentile：9.64(Nuclear Science & Technology)Okazaki, Yasuyuki*; Aoyagi, Kazuhei; Kumasaka, Hiroo*; Shinji, Masato*
Doboku Gakkai Rombunshu, F1 (Tonneru Kogaku) (Internet), 72(3), p.I_1 - I_15, 2016/00
In the rational tunnel support design, numerical analysis is powerful tool to know the estimation of the behavior before tunnel construction in the case of the special ground condition and limited similar construction. In order to evaluate the support structure quantitatively, it is necessary to understand the effect of the inhomogeneity of rock mass to the tunnel support stress in advance. In this study, tunnel excavation analysis considering the inhomogeneity of rock mass was carried out. The analysis results were compared with the stress measured in the tunnel support in the Horonobe underground research laboratory. As a result, it was revealed that the local stress measured in the tunnel support can be simulated by considering the inhomogeneity of rock mass stochastically. In addition, this study evaluated the effect of the inhomogeneity of rock mass to the tunnel support stress quantitatively by processing analysis results statistically.
Hatae, Takaki; Naito, Osamu; Kitamura, Shigeru; Sakuma, Takeshi*; Hamano, Takashi*; Nakatsuka, Masahiro*; Yoshida, Hidetsugu*
Journal of the Korean Physical Society, 49, p.S160 - S164, 2006/12
no abstracts in English
Pozdeyev, E.*; Tennant, C.*; Bisognano, J. J.*; Sawamura, Masaru; Hajima, Ryoichi; Smith, T. I.*
Nuclear Instruments and Methods in Physics Research A, 557(1), p.176 - 188, 2006/02
Times Cited Count：15 Percentile：69.07(Instruments & Instrumentation)no abstracts in English
Higuchi, Hidekazu; Momma, Toshiyuki; Nakashio, Nobuyuki; Kozawa, Kazushige; Tohei, Toshio; Sudo, Tomoyuki; Mitsuda, Motoyuki; Kurosawa, Shigenobu; Hemmi, Ko; Ishikawa, Joji; et al.
Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10
The JAERI constructed the Advanced Volume Reduction Facilities(AVRF). The AVRF consists of the Waste Size Reduction and Storage Facilities(WSRSF) and the Waste Volume Reduction Facilities(WVRF). By operating the AVRF, it will be able to produce waste packages for final disposal and to reduce the amount of the low level solid wastes. Cutting installations for large wastes such as tanks in the WSRSF have been operating since June 1999. The wastes treated so far amount to 600 m
and the volume reduction ratio is around 1/3. The waste volume reduction is carried out by a high-compaction process or melting processes in the WVRF. The metal wastes from research reactors are treated by the high-compaction process. The other wastes are treated by the melting processes that enable to estimate radioactivity levels easily by homogenization and get chemical and physical stability. The WVRF have been operating with non-radioactive wastes since February 2003 for the training and the homogeneity investigation in the melting processes. The operation with radioactive wastes will start in FY2005.
Hatae, Takaki; Kondoh, Takashi; Naito, Osamu; Nakatsuka, Masahiro*; Yoshida, Hidetsugu*
Proceedings of 12th International Symposium on Laser-Aided Plasma Diagnostics (LAPD-12) (CD-ROM), 6 Pages, 2005/09
no abstracts in English
Liu, W.; Nariai, Hideki*
Journal of Heat Transfer, 127(2), p.149 - 158, 2005/02
Times Cited Count：17 Percentile：53.46(Thermodynamics)Homogeneous nucleation, although being discounted as a mechanism for vapor formation for water in most conditions, is found being possible to occur under some extreme conditions in subcooled flow boiling. In this paper, firstly, the existence of the homogeneous nucleation governed condition is indicated. Followed, a criterion is developed to judge a given working condition is the conventional one or the homogeneous nucleation governed one. With the criterion, subcooled flow boiling data are categorized and typical homogeneous nucleation governed datasets are listed. CHF triggering mechanism for the homogeneous nucleation governed condition is proposed and verified. Parametric trends of the CHF, in terms of mass flux, pressure, inlet subcooling, channel diameter and the ratio of heated length to diameter are also studied.
Hatae, Takaki; Nakatsuka, Masahiro*; Yoshida, Hidetsugu*
Purazuma, Kaku Yugo Gakkai-Shi, 80(10), p.870 - 882, 2004/10
A high performance phase conjugate mirror by stimulated Brillouin scattering (SBS-PCM) is applied to Thomson scattering diagnostics in JT-60U for the first time. To improve the measurement performance, two developments were performed with SBS-PCM. First, we developed a new optical design to provide a double-pass scattering scheme with SBS-PCM. A laser beam passing through the plasma is reflected by the SBS-PCM, and a reflected beam returned back through the same path as coming one by the phase conjugate effect, and passed through the plasma again. The double path Thomson scattering scheme demonstrated in JT-60U plasma that a factor of 1.6 increase of the scattered light in contrast with single-pass scattering. Second, an improvement of the output power of YAG laser system using the SBS-PCM was performed. As a result, average power was increased over 8 times in contrast with conventional system, and was achieved up to 368 W (7.4 J 
50 Hz). A multi-pass Thomson scattering scheme is also proposed based on the results of double-pass scattering.
Yamauchi, Toshihiko
Japanese Journal of Applied Physics, 43(9A), p.6473 - 6474, 2004/09
Times Cited Count：0 Percentile：0.00(Physics, Applied)The output pattern of He-Ne laser that passes through the optical glass fiber bundle used for free electron laser etc. depends on the weight of load (modulation of transverse mode). The increment of pattern radius exponentially increases with the load. It is considered that the micro bending causes this increment. Next, the estimated delay time also exponentially increases with the weight of load, and the estimated delay time is the extent of pico-second.
Sawamura, Masaru; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Minehara, Eisuke; Nagai, Ryoji; Nishimori, Nobuyuki
Free Electron lasers 2003, p.II_31 - II_32, 2004/00
no abstracts in English
Nagao, Tatsuya*; Igarashi, Junichi
Journal of the Physical Society of Japan, 72(9), p.2381 - 2384, 2003/09
Times Cited Count：10 Percentile：54.40(Physics, Multidisciplinary)We examine the mechanism of the X-ray diffraction process by including the Thomson scattering (TS) term in addition to the resonant X-ray scattering (RXS) term near the Ce L absorption edge in the antiferroquadrupole (AFQ) ordering phase of CeB. Assuming the AFQ order in the 4f states but without any lattice distortion, we obtain the TS intensity comparable to the RXS intensity, owing to the anisotropic charge distribution of 4f states. The present calculation reproduces well the interference pattern between the TS and RXS terms for the (5/2,3/2,3/2) spot observed in the recent experiment. The result suggests that the TS signal as well as the main peak of the RXS signal are a direct reflection of the AFQ order in CeB.
Norisue,Tomohisa*; Kida, Yusuke*; Masui, Naoki*; Tran-Cong-Miyata, Q.*; Maekawa, Yasunari; Yoshida, Masaru; Shibayama, Mitsuhiro*
Macromolecules, 36(16), p.6202 - 6212, 2003/08
Times Cited Count：80 Percentile：89.40(Polymer Science)The shrinking kinetics of poly(N-isopropylacrylamide) (PNIPA) gels has been studied for two types of PNIPA gels prepared by (i) copolymerization of constituent monomer and cross-linker and (ii) 
-ray irradiation in the PNIPA solutions in order to investigate the role of cross-linking on shrinking kinetics. The shrinking kinetics of the monomer cross-linked gels is quite similar to that of the polymer cross-linked gels. On the other hand, a significant difference was found when the microscopic structure and the dynamics were investigated by small-angle neutron scattering (SANS) and static/dynamic light scattering (SLS/DLS). The degree of built-in inhomogeneities and dynamic fluctuations were evaluated as a function of the cross-linking degree and the gel preparation temperature by intensity decomposition methods for both types of gels. It is concluded that the monomer cross-linked gels have extra built-in inhomogeneities due to the spatial distribution of crosslinks in addition to the frozen concentration fluctuations inherent in polymer gels.
Sawamura, Masaru; Nagai, Ryoji; Kikuzawa, Nobuhiro; Hajima, Ryoichi; Nishimori, Nobuyuki; Minehara, Eisuke
Proceedings of 28th Linear Accelerator Meeting in Japan, p.384 - 386, 2003/08
no abstracts in English
-particle diagnostics by CO laser collective Thomson scattering in ITERKondoh, Takashi; Richards, R. K.*; Hutchinson, D. P.*; Sugie, Tatsuo; Costley, A. E.*; Miura, Yukitoshi; Lee, S.*
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/07
In order to understand the behavior of alpha-particles which are the dominant heat source in a burning plasma, it is necessary to measure the spatial distribution of the number of the alpha-particles and their energy spectrum. A collective Thomson scattering (CTS) system based on a pulsed CO laser is being developed and is under consideration for alpha-particle measurements on ITER. Heating beam ions (E = 1 MeV) are normally co-injected and have a similar velocity with alpha-particles in ITER. The CTS measurement can not, in general, distinguish beam ions and alpha-particles which have the same velocity. A vertical scattering geometry to distinguish between beam ions and alpha-particles is proposed. Calculations have shown that the vertically viewing CTS can resolve counter-travelling alphas without being masked by beam ions. Preliminary design of a beam line and a receiver system with the vertical scattering geometry has been developed. A proof-of-principle test on the CTS system using the JT-60U plasma is being conducted.
spatial profile from background light in incoherent Thomson scattering diagnosticNaito, Osamu; Hatae, Takaki
JAERI-Research 2002-033, 9 Pages, 2003/03
JAERI-Research-2002-033.pdf:0.46MB
A simulation study on the feasibility of inferring spatial profile along with electron temperature and density in Thomson scattering diagnostic is presented. The background signal, which is usually discarded after subtracted from the Thomson scattered signal, is used in the reconstruction procedure. If the contribution from line radiation to the background signal is by one order of magnitude smaller than that from bremsstrahlung, a fairly accurate profile can be reconstructed.
Yamane, Yuichi; Miyoshi, Yoshinori; Watanabe, Shoichi; Yamamoto, Toshihiro
Nuclear Technology, 141(3), p.221 - 232, 2003/03
Times Cited Count：6 Percentile：40.84(Nuclear Science & Technology)no abstracts in English
spatial profile in incoherent Thomson scattering diagnosticNaito, Osamu; Hatae, Takaki
Review of Scientific Instruments, 74(3), p.1374 - 1376, 2003/03
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)A simulation study on the feasibility of inferring spatial profile along with electron temperature and density in Thomson scattering diagnostic is presented. The background signal, which is usually discarded after subtracted from the Thomson scattered signal, is used in the reconstruction procedure. If the background signal consists predominantly of bremsstrahlung radiation, a fairly accurate profile can be reconstructed. Additional benefit of including background signal in the reconstruction is the reduction of errors in the inferred electron temperature and density.
