Momentum exchange functions model for SIMMER-III and SIMMER-IV

Tobita, Yoshiharu*; Kondo, Satoru; Suzuki, Toru*

JAEA-Research 2024-011, 39 Pages, 2024/10

JAEA-Research-2024-011.pdf:1.67MB

The SIMMER-III and SIMMER-IV computer code, developed at the Japan Atomic Energy Agency (JAEA), is a two- and three-dimensional, multi-velocity-field, multi-component fluid-dynamics model, coupled with a space- and time-dependent neutron kinetics model. The codes have been used widely for simulating complex phenomena during core-disruptive accidents in liquid-metal fast reactors. In the multi-velocity-field fluid dynamics, momentum exchange functions (MXFs) are required for treating inter-field drag and fluid-structure friction effects and thereby for accurately simulating reactivity effects of relative motion of core materials. Up to 8 velocity fields can be used in SIMMER-III and SIMMER-IV, with each field exchanging momentum with other fields and structure surfaces. Since both theoretical and experimental knowledge of the momentum exchange processes for a multi-component, multi-velocity flows is limited, the developed MXF formulations are based on engineering correlations of steady-state two-phase flows. Multi-phase flow regimes for both the pool and channel flows are modeled with using an appropriate averaging procedure such as to avoid abrupt changes in MXFs at flow regime transition. The MXF model, together with the multi-phase flow topology and interfacial area model, has been extensively tested through the code assessment (verification and validation) program, which has demonstrated that many of the problems associated with limitation of two velocity fields and simplistic modeling in the previous codes were resolved.

Heat transfer coefficients model for SIMMER-III and SIMMER-IV

Brear, D. J.*; Kondo, Satoru; Sogabe, Joji; Tobita, Yoshiharu*; Kamiyama, Kenji

JAEA-Research 2024-009, 134 Pages, 2024/10

JAEA-Research-2024-009.pdf:2.45MB

The SIMMER-III/SIMMER-IV computer codes are being used for liquid-metal fast reactor (LMFR) core disruptive accident (CDA) analysis. The sequence of events predicted in a CDA is often influenced by the heat exchanges between LMFR materials, which are controlled by heat transfer coefficients (HTCs) in the respective materials. The mass transfer processes of melting and freezing, and vaporization and condensation are also controlled by HTCs. The complexities in determining HTCs in a multi-component and multi-phase system are the number of HTCs to be defined at binary contact areas of a fluid with other fluids and structure surfaces, and the modes of heat transfer taking into account different flow topologies representing flow regimes with and without structure. As a result, dozens of HTCs are evaluated in each mesh cell for the heat and mass transfer calculations. This report describes the role of HTCs in SIMMER-III/SIMMER-IV, the heat transfer correlations implemented and the calculation of HTCs in all topologies in multi-component, multi-phase flows. A complete description of the physical basis of HTCs and available experimental correlations is contained in Appendices to this report. The major achievement of the code assessment program conducted in parallel with code development is summarized with respect to HTC modeling to demonstrate that the coding is reliable and that the model is applicable to various multi-phase problems with and without reactor materials.

High temperature gas-cooled reactors

Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.

High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02

https://doi.org/10.1016/C2018-0-05383-9

As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.

Phase 1 code assessment of SIMMER-III; A Computer program for LMFR core disruptive accident analysis

Kondo, Satoru; Tobita, Yoshiharu

JAEA-Research 2019-009, 382 Pages, 2020/03

JAEA-Research-2019-009.pdf:22.82MB

The SIMMER-III computer code, developed at the Japan Atomic Energy Agency (JAEA, the former Power Reactor and Nuclear Fuel Development Corporation), is a two-dimensional, multi-velocity-field, multi-component fluid-dynamics code, coupled with a space- and time-dependent neutron kinetics model. The code is being used widely for simulating complex phenomena during core-disruptive accidents (CDAs) in liquid-metal fast reactors (LMFRs). In parallel to the code development, a comprehensive assessment program was performed in two phases: Phase 1 for verifying individual fluid-dynamics models; and Phase 2 for validating its applicability to integral phenomena important to evaluating LMFR CDAs. The SIMMERIII assessment program was participated by European research and development organizations, and the achievement of Phase 1 was compiled and synthesized in 1996. This report has been edited by revising and reproducing the original 1996 informal report, which compiled the achievement of Phase 1 assessment. A total of 34 test problems were studied in the areas: fluid convection, interfacial area and momentum exchange, heat transfer, melting and freezing, and vaporization and condensation. The problems identified have been reflected to the Phase 2 assessment and later model development and improvement. Although the revisions were made in the light of knowledge base obtained later, the original individual contributions by the participants, both positive and negative, are retained except for editorial changes.

X-ray absorption spectroscopy in the heavy Fermion compound -YbAlB at high magnetic fields

Terashima, Taku*; Matsuda, Yasuhiro*; Kuga, Kentaro*; Suzuki, Shintaro*; Matsumoto, Yosuke*; Nakatsuji, Satoru*; Kondo, Akihiro*; Kindo, Koichi*; Kawamura, Naomi*; Mizumaki, Masaichiro*; et al.

Journal of the Physical Society of Japan, 84(11), p.114715_1 - 114715_4, 2015/11

https://doi.org/10.7566/JPSJ.84.114715

Improvement in oil seal performance of gas compressor in HTTR, 2

Nemoto, Takahiro; Kaneshiro, Noriyuki*; Sekita, Kenji; Furusawa, Takayuki; Kuroha, Misao; Kawakami, Satoru; Kondo, Masaaki

JAEA-Technology 2015-006, 36 Pages, 2015/03

JAEA-Technology-2015-006.pdf:16.77MB

The High-Temperature engineering Test Reactor (HTTR) has been developed for establishing and upgrading the technical basis of HTGR.HTTR facilities have their structures, systems and a lot of components including reciprocating gas compressors, commonly used to extract and/or discharge reactor coolant helium gas contained in primary/secondary coolant systems. From the fact of the operational experiences of these compressors, seal-oil leakage has been frequently observed, although rod-seal mechanisms with complicated structures are equipped and improved for preventing coolant helium gas. So, we tried to change the rod-seal materials which might be a primary reason of frequent seal-oil leakage, that resulted in decreasing a mass and frequently of seal-oil leakage. It is confirmed that it is important to select adequate materials of rod seal for sliding speed of the piston of the compressor to prevent seal-oil leakage. Additionally, the procedure to estimate seal-oil leakage for each compressor is discussed. This report describes the results of investigation for improvement on seal-oil leak tightness of the compressors in HTTR facilities.

Recent progress and status of Monju

Kondo, Satoru; Deshimaru, Takehide; Konomura, Mamoru

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Safe Technologies and Sustainable Scenarios (FR-13) (USB Flash Drive), 6 Pages, 2013/03

http://www.iaea.org/nuclearenergy/nuclearpower/Downloadable/Meetings/2013/2013-03-04-03-07-CF-NPTD/T9.1/T9.1.deshimaru.pdf

Monju, a 280-MWe prototype sodium-cooled fast reactor of, restarted its test operation in 2010. The zero-power tests were successfully conducted. It's major achievement was accurate prediction of reactor physics parameters with a core including americium-rich fuel. The reactor, however, has been put into a stand-by mode again since the 3.11 Fukushima-Daiichi accident. The roles shall not change: demonstrating stable power generation and actinide burning; providing technology and knowledge base for future SFRs; and using the plant as an international research facility.

Partial stripping of Ag atoms from silver bilayer on a Au(111) surface accompanied with the reductive desorption of hexanethiol SAM

Kondo, Toshihiro*; Tamura, Kazuhisa; Takakusagi, Satoru*; Kitamura, Ken*; Takahashi, Masamitsu; Mizuki, Junichiro; Uosaki, Kohei*

Journal of Solid State Electrochemistry, 13(7), p.1141 - 1145, 2009/07

https://doi.org/10.1007/s10008-008-0764-3

The interfacial structures of Ag bilayer prepared by underpotential deposition on Au(111) were determined by STM and SXS before and after oxidative adsorption and after desorption of a SAM of CSH in alkaline ethanol solution. While no structural change was observed after oxidative formation of CSH SAM on the Ag/Au(111) in an ethanol solution containing 20 mM KOH and 0.1 mM CSH, some of the Ag atoms in the bilayer were stripped when the SAM was reductively desorbed.

Performance-based improvement of the leakage rate test program for the reactor containment of HTTR; Adoption of revised test program containing "Type A, Type B and Type C tests"

Kondo, Masaaki; Kimishima, Satoru*; Emori, Koichi; Sekita, Kenji; Furusawa, Takayuki; Hayakawa, Masato; Kozawa, Takayuki; Aono, Tetsuya; Kuroha, Misao; Ouchi, Hiroshi

JAEA-Technology 2008-062, 46 Pages, 2008/10

JAEA-Technology-2008-062.pdf:11.62MB

The reactor containment of HTTR is tested to confirm leak-tight integrity of itself. "Type A test" has been conducted in accordance with the standard testing method in JEAC4203 since the preoperational verification of the containment was made. Type A tests are identified as basic one for measuring containment leakage rate, it costs much, however. Therefore, the test program for HTTR was revised to adopt an efficient and economical alternatives including "Type B and Type C tests". In JEAC4203-2004, following requirements are specified for adopting alternatives: upward trend of leakage rate by Type A test due to aging should not be recognized; criterion of combined leakage rate with Type B and Type C tests should be established; the criteria for Type A test and combined leakage rate test should be satisfied; correlation between the leakage rates by Type A test and combined leakage rate test should be recognized. Considering the performances of the tests, the policies of corresponding to the requirements were developed, which were accepted by the regulatory agency. This report presents an outline of the tests, identifies issues on the conventional test and summarizes the policies of corresponding to the requirements and of implementing the tests based on the revised program.

Structure of Au(111) and Au(100) single-crystal electrode surfaces at various potentials in sulfuric acid solution determined by in situ surface X-ray scattering

Kondo, Toshihiro*; Morita, Jun*; Hanaoka, Kazuya*; Takakusagi, Satoru*; Tamura, Kazuhisa; Takahashi, Masamitsu; Mizuki, Junichiro; Uosaki, Kohei*

Journal of Physical Chemistry C, 111(35), p.13197 - 13204, 2007/09

https://doi.org/10.1021/jp072601j

Potential-dependent surface structures of Au(111) and Au(100) single-crystal electrodes in a 50 mM HSO solution were investigated at an atomic level using in situ surface X-ray scattering (SXS) techniques. It was confirmed that both the Au(111) and Au(100) surfaces were reconstructed with an attached submonolayer of an oxygen species, most probably water, at 0 V (vs Ag/AgCl). Results at +0.95 V supported a previously suggested model for both the Au(111) and the Au(100) electrodes that, based on infrared and scanning tunneling microscopy measurements, the surfaces were a (11) structure with the coadsorbed sulfate anion and hydronium cation (HO). At +1.05 V, where a small amount of an anodic current flowed, adsorption of a monolayer of oxygen species was observed on both surfaces.