Analysis of pulverization property of the collision-plate-type jet mill

Kawaguchi, Koichi; Segawa, Tomoomi; Ishii, Katsunori

Funtai Kogakkai-Shi, 59(6), p.283 - 290, 2022/06

https://doi.org/10.4164/sptj.59.283

In the Japan Atomic Energy Agency, in order to effectively use the out-of-standard pellets in the fuel manufacturing process for high-speed furnaces, we are developing techniques for crushing and reusing them with raw material powder. By analyzing in detail the particle size distribution before and after grinding, it was shown that the grinding powder is composed of three different component particles having different characteristics of the particle size distribution. In addition, we examined the method of predicting pulverized powder particle size distribution from the supply powder particle size distribution.

Contribution to risk reduction in decommissioning works by the elucidation of basic property of radioactive microparticles (Contract research); FY2018 Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development

Collaborative Laboratories for Advanced Decommissioning Science; Ibaraki University*

JAEA-Review 2019-041, 71 Pages, 2020/03

JAEA-Review-2019-041.pdf:3.38MB

JAEA/CLADS, has been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") since FY2018. The Project aims at solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. For this purpose, intelligence has been collected from all over the world, and basic research and human resource development have been promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. Among the adopted proposals in FY2018, this report summarizes the research results of the "Contribution to Risk Reduction in Decommissioning Works by the Elucidation of Basic Property of Radioactive Microparticles". In order to establish the decommissioning procedures (recovery of the melted fuels, decontamination inside the reactors, ensuring the safety of the workers, etc.) of the Fukushima Daiichi Nuclear Power Station, radioactive microparticles released by the accident are an important information source for clarifying what had happened inside the reactors in the course of the accident. The purpose of the present study is to obtain detailed knowledge on the basic properties (particle size, composition, electrical/optical properties, etc.) of the radioactive microparticles, as well as to further elucidate the various properties of the radioactive microparticles including the quantitative evaluation of alpha-ray-emitters, through the Japan-UK synergetic research. Thus, we are conducting research and development that will contribute to the comprehensive works towards the risk reduction in the "decommissioning" plan.

Code-B-2.5.2 for stress calculation for SiC-TRISO fuel particle

Aihara, Jun; Goto, Minoru; Ueta, Shohei; Tachibana, Yukio

JAEA-Data/Code 2019-018, 22 Pages, 2020/01

JAEA-Data-Code-2019-018.pdf:1.39MB

Concept of Pu-burner high temperature gas-cooled reactor (HTGR) was proposed for purpose of more safely reducing amount of recovered Pu. In Pu-burner HTGR concept, coated fuel particle (CFP), with ZrC coated yttria stabilized zirconia (YSZ) containing PuO (PuO-YSZ) small particle and with tri-structural isotropic (TRISO) coating, is employed for very high burn-up and high nuclear proliferation resistance. ZrC layer is oxygen getter. On the other hand, we have developed Code-B-2.5.2 for prediction of pressure vessel failure probabilities of SiC-tri-isotropic (TRISO) coated fuel particles for HTGRs under operation by modification of an existing code, Code-B-2. The main purpose of modification is preparation of applying code for CFPs of Pu-burner HTGR. In this report, basic formulae are described.

Medical application of the PHITS code, 2; Acceleration by parallel computing

Furuta, Takuya; Sato, Tatsuhiko

Igaku Butsuri, 35(3), p.264 - 268, 2015/00

Time-consuming Monte Carlo dose calculation becomes feasible owing to the development of computer technology. However, the recent development is due to emergence of the multi-core high performance computers. Therefore, parallel computing becomes a key to achieve good performance of software programs. A Monte Carlo simulation code PHITS contains two parallel computing functions, the distributed-memory parallelization using protocols of MPI and the shared-memory parallelization using OpenMP directives. Users can choose the two functions according to their needs. This paper gives the explanation of the two functions with their advantages and disadvantages. Some test applications are also provided to show their performance using a typical multi-core high performance workstation.

Progress of boundary plasma investigation toward ITER

Shimada, Michiya

Purazuma, Kaku Yugo Gakkai-Shi, 80(3), p.222 - 226, 2004/03

https://doi.org/10.1585/jspf.80.222

Discussion is made on objectives of edge plasma and plasma-wall interaction studies, divertor performance projection of ITER and key R&D issues on plasma-wall interaction including material issues, tritium retention, and transient events like ELMs and disruptions. A perspective of future development is discussed for the purpose of projection to and control of ITER plasma.

Preparation of TiO nanoparticles by pulsed laser ablation; Ambient pressure dependence of crystallization

Matsubara, Masakazu*; Yamaki, Tetsuya; Ito, Hisayoshi; Abe, Hiroaki*; Asai, Keisuke*

Japanese Journal of Applied Physics, Part 2, 42(5A), p.L479 - L481, 2003/05

Pulsed laser ablation with a KrF excimer laser was used to prepare fine particles of titanium dioxide (TiO). The ablation in an atmosphere of Ar and O (5:5) at total pressures of 1 Torr led to the formation of TiO nanoparticles composed of anatase and rutile structures without any suboxides. The weight fraction of the rutile/anatase crystalline phases was controlled by the pressure of the Ar/O gas. The TiO nanoparticles had a spherical shape and their size, ranging from 10 and 14 nm, also appeared to be dependent on the ambient pressure.

Two-dimensional particle simulation of the flow control in SOL and divertor plasmas

Takizuka, Tomonori; Hosokawa, Masanari*; Shimizu, Katsuhiro

Journal of Nuclear Materials, 313-316(1-3), p.1331 - 1334, 2003/03

https://doi.org/10.1016/S0022-3115(02)01513-1

In course of tokamak fusion research, particle and heat control is one of the most crucial issues. Helium ash exhaust and impurity retention in the divertor region owe to the plasma flow towards divertor plate. The localization of heat load on the plate depends on the flow pattern. Accordingly, particle and heat control can be achieved by the proper control of the flow in SOL and divertor plasmas. In this paper, the flow control is studied with two-dimensional particle simulations by PARASOL (PARticle Advanced simulation for SOL and divertor plasmas) code. Magnetic field configuration with separatrix like a tokamak divertor configuration is given. Hot particle source is put in the core plasma. Recycling cold particle source is located near the divertor plate. Particle source of gas puff in the SOL plasma is given for the flow control. Divertor biasing is available by changing the electrostatic potential on the plates. Effects of gas puff and biasing on the flow are studied. Controllability is evaluated from simulation results.

Accumulation and potential dissolution of Chernobyl-derived radionuclides in river bottom sediments

Sanada, Yukihisa*; Matsunaga, Takeshi; Yanase, Nobuyuki; Nagao, Seiya; Amano, Hikaru; Takada, Hideshige*; Tkachenko, Y.*

Applied Radiation and Isotopes, 56(5), p.751 - 760, 2002/04

https://doi.org/10.1016/S0969-8043(01)00274-3

Areas contaminated with radionuclides from the Chernobyl nuclear accident have been identified in Pripyat River near the Chernobyl Nuclear Power Plant. The bottom sediments contained Cs (10 - 10 Bq/m) within 0-30 cm depth, which is comparable to the ground soil of in the vicinity of the nuclear power plant (the Exclusion Zone). The sediments also accumulated Sr (10 Bq/m ), Pu (10 Bq/m ), Am (10 Bq/m ) derived from the accident.The comparison of these inventories with those of the released radionuclides at the accident and the experimental analysis using the selective sequential extraction of the radionuclides in the sediments suggest that the potential mobility of Cs and Pu is low compared with Sr in the bottom sediment, while the potential dissolution of Sr from the river bottom sediment should be taken into account with respect to the long-term radiological influence on the aquatic environment.

Reactor-grade plutonium burning by pebble bed type HTGRs

Fujimoto, Nozomu; Yamashita, Kiyonobu

Proc. of Int. Conf. on Future Nuclear Systems (Global'97), 2, p.957 - 962, 1997/00

no abstracts in English

Development of Monte Carlo machine for particle transport problem

Higuchi, Kenji; ;

Journal of Nuclear Science and Technology, 32(10), p.953 - 964, 1995/10

https://doi.org/10.3327/jnst.32.953

no abstracts in English