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JAEA Reports

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$$_{2}$$ (PuO$$_{2}$$-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.

Journal Articles

Model updates and performance evaluations on fuel performance code FEMAXI-8 for light water reactor fuel analysis

Udagawa, Yutaka; Amaya, Masaki

Journal of Nuclear Science and Technology, 56(6), p.461 - 470, 2019/06

 Times Cited Count:3 Percentile:57.07(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Applicability of statistical geometry model to light water moderating systems

Mori, Takamasa; Kojima, Kensuke*; Suyama, Kenya

JAEA-Research 2018-010, 57 Pages, 2019/02

JAEA-Research-2018-010.pdf:6.25MB

In order to estimate applicability of the statistical geometry model (STGM) of MVP/GMVP, a parametric study in infinite geometry and criticality safety analyses for direct disposal of spent fuel in simple finite geometry have been carried out by using the MVP Monte Carlo code. It has been found that calculations with STGM for larger fuel spheres give larger thermal utilization factors and larger infinite multiplication factors compared with explicit random models in the range of fuel sphere packing fraction between 6.5 % and 63.3 %. Substantial differences are not observed between the results with two nearest neighbor distributions (NNDs); that given by the MCRDF code and the analytical expression based on a statistically uniform distribution. It is inferred that the overestimation by STGM is caused by the facts that STGM cannot take account of the surroundings of each neutron, whether a fuel sphere rich region or a water moderator rich one, because STGM always uses an NND averaged over such surroundings and that STGM, therefore, cannot take the effect of consecutive scatterings in the water moderator into account.

JAEA Reports

Development of fuel performance code FEMAXI-8; Model improvements for light water reactor fuel analysis and systematic validation

Udagawa, Yutaka; Yamauchi, Akihiro*; Kitano, Koji*; Amaya, Masaki

JAEA-Data/Code 2018-016, 79 Pages, 2019/01

JAEA-Data-Code-2018-016.pdf:2.75MB

FEMAXI-8 is the latest version of the fuel performance code FEMAXI developed by JAEA. A systematic validation work has been achieved against 144 irradiation test cases, after many efforts have been made, in development of new models, improvements in existing models and the code structure, bug-fixes, construction of irradiation-tests database and other infrastructures.

Journal Articles

Sintering behavior of (U,Ce)O$$_{2}$$ and (U,Pu)O$$_{2}$$

Nakamichi, Shinya; Hiroka, Shun; Sunaoshi, Takeo*; Kato, Masato; Nelson, A.*; McClellan, K.*

Transactions of the American Nuclear Society, 113(1), p.617 - 618, 2015/10

Cerium dioxide has been used as a surrogate material for plutonium dioxide. Dorr et al reported the use of hyper-stoichiometric conditions causes the start of shrinkage of (U,Ce)O$$_{2}$$ at low temperature compared with the sintering in reducing atmosphere. However, the precise stoichiometry of the samples investigated was not controlled or otherwise monitored, preventing any quantitative conclusions regarding the similarities or differences between (U,Ce)O$$_{2}$$ and (U,Pu)O$$_{2}$$. The motivation for the present work is therefore to compare the sintering behavior of MOX and the (U,Ce)O$$_{2}$$ MOX surrogates under controlled atmospheres to assess the role of oxygen defects on densification in both systems.

JAEA Reports

Study of the quality of vipac oxide fuel obtained by pyro-processing

;

JNC TN9400 2000-054, 84 Pages, 2000/04

JNC-TN9400-2000-054.pdf:7.15MB

This report describes accomplishment of the study on the quality of vipac (vibro-packed) oxide fuel obtained by pyrochemical processing (molten salt electrolytic processing). This study is intended to contribute to the design study of the pyro-reprocessing-vipac fuel recycling system of oxide fuel. In this study, vibro-packing experiment has been conducted using granular U0$$_{2}$$ obtained by molten salt electrolytic processing (cold experiment). The oxide pyro process developed by Research lnstitute of Atomic Reactors (RIAR) is the method in which the sintered oxide is electrically deposited on the cathode at approximately 600$$^{circ}$$C. 0xide granules for vipac fuel are obtained by crushing the oxide deposited on the cathode. This process is also developed as recycle process because it is capable of FP separation. Also in Japan, this process is studied as one of the new FBR fuel recycling systems. ln this study, we made an effort to clarify the mechanisms of vibro-packing of the electrically obtained granules, which influence on the effective parameters of vibro-packing density and fuel particles size distribution in the fuel cladding in case of non-sphere particles of the granules. As a result of the study, smear density of 75% and almost uniform distribution of U0$$_{2}$$ particles have been taken in the experiment, and much knowledge for the improvement of the vibro-packing quality has been found. And the possibility of the smear density over 80% and the uniform distribution of U0$$_{2}$$ particles has been suggested in this study.

JAEA Reports

None

; Yasu, Takami; ;

PNC TN8410 97-107, 53 Pages, 1997/05

PNC-TN8410-97-107.pdf:1.27MB

None

JAEA Reports

Effects of Noble Metal Elements on Properties of Simulated Vitrified Products for High-Level Liquid Waste

; ; Takahashi, Takeshi

PNC TN8410 91-247, 29 Pages, 1991/12

PNC-TN8410-91-247.pdf:0.8MB

The effects of noble metal elements such as ruthenium, rhodium and palladium on the viscosity and electrical resistivity of simulated nuclear waste glass were studied. The glass enriched with noble metals showed the viscosity of a non-Newtonian fluid. The viscosity of the waste g1ass with 10 wt% RuO$$_{2}$$ was 3 to 7 times higher than that of glass without noble metals. The RuO$$_{2}$$ was mainly responsible for the increase in viscosity for the glass enriched with noble metals. Electrical resistivity of the glass with 15 wt% RuO$$_{2}$$, was one seventh to two orders of magnitude lower than that of glass without noble metals. The three noble metals contributed to the decrease in resistivity. The quantitative effects of noble metals on these properties were obtained.

Oral presentation

Diffusion coefficients of fission products in UO$$_{2}$$ with molecular dynamics method

Sato, Isamu; Matsumoto, Taku; Koyama, Shinichi; Arima, Tatsumi*

no journal, , 

Diffusion coefficients of fission product elements, Zr, Nd, Ba and Sr in UO$$_{2}$$ crystal which are substituent cations for U were evaluated with molecular dynamics. The diffusion coefficients of Nd and Ba/Sr which are trivalent and divalent cations are greater than those of U and Zr that are tetravalent cations.

Oral presentation

Discovery of the shape controllable cavity surrounded by facets in ceramics

Serizawa, Hiroyuki

no journal, , 

My investigation on cavities in ceramics was triggered by the unexpected discovery of a polyhedral cavity in a UO$$_{2}$$ matrix. The SEM image that attracted my attention was a cavity observed in the fracture surface of a single crystal of UO$$_{2}$$ that was heat-treated in helium at 90 MPa, followed by annealing at 1573 K for 1 h. It was clear that the cavity was a negative crystal that was formed by the precipitation of helium during heat treatment after Hot Isostatic Pressing (HIP) injection. In a series of experiments, I noticed that the shape of the negative crystal changes depending on the heat-treatment history. A truncated octahedron-type, an octa-triacontahedron-type, and a pentacontahedron-type negative crystal were observed. Our study implies that the shape of the negative crystal should change depending on the helium inner pressure enclosed in the negative crystal.

Oral presentation

Recent research on image crystals; Discovery of shape-controllable cavities surrounded by facets in ceramics

Serizawa, Hiroyuki

no journal, , 

My investigation on cavities in ceramics was triggered by the unexpected discovery of a polyhedral cavity in a UO$$_{2}$$ matrix. In a series of experiments, I noticed that the shape of the negative crystal changes depending on the heat-treatment history. In general, it is difficult to control arbitrarily the shapes of these polyhedral negative crystals embedded in a solid medium; however, the shape can easily be controlled using the helium injection method. Our research team named the shape controlled negative crystal as image crystal.

Oral presentation

Oral presentation

Nonstoichiometry, electrical conductivity and oxygen diffusion in PuO$$_{2}$$

Kato, Masato; Watanabe, Masashi; Nakamura, Hiroki; Machida, Masahiko

no journal, , 

no abstracts in English

Oral presentation

Micro-Raman spectroscopy combined with alpha track detection to identify chemical forms of uranium particles

Yomogida, Takumi; Esaka, Fumitaka; Magara, Masaaki

no journal, , 

In this study, we developed a micro-Raman spectroscopy technique combined with alpha track-detection to identify chemical forms of uranium particles. U$$_{3}$$O$$_{8}$$ and UO$$_{2}$$ particles were used as samples. Films containing uranium-bearing particles were exposed to alpha track detectors (TNF-1) for a few months. The location of uranium particles in the films were identified by observing alpha tracks which caused by spontaneous fission of uranium. The characteristic Raman bands which derive from U$$_{3}$$O$$_{8}$$ and UO$$_{2}$$ structures were observed in the Raman spectra of uranium particles.

Oral presentation

Secondary ion mass spectrometry combined with micro-Raman spectroscopy for isotopic and chemical analysis of individual uranium particles

Yomogida, Takumi; Esaka, Fumitaka; Magara, Masaaki

no journal, , 

Analysis of individual uranium particles in environmental samples from nuclear facilities is useful for detecting nuclear activity. Uranium isotope ratios in the samples are measured to detect nuclear activities related to production of nuclear weapons. We can detect the nuclear activities such as refining, conversion and enrichment process by determination of the chemical form of uranium particles. In this study, we developed a secondary ion mass spectrometry combined with micro-Raman spectroscopy for isotopic and chemical analysis of individual uranium particles. The developed methods have been applied to the analysis of reference uranium materials. As a result, the isotope ratios and the chemical form of individual uranium particle can be analyzed with the proposed method.

Oral presentation

Application of micro-Raman spectroscopy to chemical form identification of uranium particles with micro-meter size

Yomogida, Takumi; Esaka, Fumitaka; Magara, Masaaki

no journal, , 

Recently, we are applying micro-Raman spectroscopy to the identification of the chemical forms of individual uranium particles for nuclear safeguards. In this study, a micro-Raman spectroscopy technique combined with particle detection by scanning electron microscope and micro manipulation was developed to identify chemical forms of uranium particles. The characteristic Raman bands at 445 and 1160 cm$$^{-1}$$ assigned to UO$$_{2}$$ structures were observed in the Raman spectrum of a uranium particle with a diameter of 1 $$mu$$m. The particle shape was preserved after the Raman measurement, which indicated the particle was not burned by the laser beam. In conclusion, the chemical forms of individual uranium particles with micro-meter size can be analyzed with the proposed method without damaging the particles.

Oral presentation

Study on the physical properties of non-stoichiometric oxide fuels with high minor actinide contents, 6; Evaluation of fuel properties for simulated MA containing oxide fuel

Muta, Hiroaki*; Kato, Naoki*; Tanaka, Kosuke; Matsuda, Tetsushi*; Oishi, Yuji*; Kurosaki, Ken*; Yamanaka, Shinsuke*

no journal, , 

Effect of MA and FP addition on thermo-mechanical properties of UO$$_{2}$$ were investigated.

Oral presentation

Study on the physical properties of non-stoichiometric oxide fuels with high minor actinide contents, 7; Estimation of fuel properties for large amount of simulated MA containing oxide fuel

Kato, Naoki*; Muta, Hiroaki*; Tanaka, Kosuke; Matsuda, Tetsushi*; Oishi, Yuji*; Kurosaki, Ken*; Yamanaka, Shinsuke*

no journal, , 

Physical properties of sintered UO$$_{2}$$ specimens containing over 10% simulated MA were investigated. Based on the measured data, a prediction method for the properties was introduced.

Oral presentation

Micro-Raman mapping combined with X-ray detection for chemical state analysis of individual uranium particles in environmental samples

Yomogida, Takumi; Esaka, Fumitaka; Magara, Masaaki

no journal, , 

Chemical state analysis of individual uranium particles in environmental samples is useful tool for deducing the nuclear activity at nuclear facilities. However, coexisting elements in uranium baring particles would interfere with chemical state analysis by micro-Raman spectroscopy. In this study, X-ray detection and micro-Raman spectroscopy were applied in combination to reduce an influence of coexisting elements during the micro-Raman measurement. The method has been applied to the analysis of reference uranium particles and environmental samples. As a result, the chemical form of individual uranium particles can be analyzed thanks to the optimization of the analyzed spot at a micro-Raman measurement. The characteristic Raman band at 445 cm$$^{-1}$$ assigned to UO$$_{2}$$ structures were observed from the uranium-baring particle in an environmental sample.

Oral presentation

Micro-Raman spectroscopy combined with micro-sampling for chemical state analysis of individual uranium particles with sub-micrometer size

Yomogida, Takumi; Esaka, Fumitaka; Miyamoto, Yutaka

no journal, , 

Identification of the chemical forms of individual uranium particles in environmental samples is important tool for deducing the nuclear activity at nuclear facilities. However, there are few reports on the chemical state analysis of sub-micron sized uranium particles. In this study, micro-sampling and micro-Raman spectroscopy were applied in combination to analyze uranium particles with sub-micrometer size. As a result, the chemical form of individual uranium particles with sub-micrometer size can be analyzed non-destructively thanks to the optimization of the laser power at a micro-Raman measurement.

25 (Records 1-20 displayed on this page)