Subchannel analysis of 37-rod tight-lattice bundle experiments for reduced-moderation water reactor

Nakatsuka, Toru; Tamai, Hidesada; Akimoto, Hajime

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10

The subchannel analysis code NASCA was applied to critical power prediction of 37-rod tight-lattice bundle experiments which JAERI has been carrying out to confirm the thermal-hydraulic feasibility of the RMWR. The NASCA can yield good predictions of critical power for the gap width of 1.3 mm while the prediction accuracy of critical power deteriorated in case of the gap width of 1.0 mm. Predicted BT positions agree with the experimental results. Models in the code will be improved to consider the effect of the gap width based on further studies in the future.

Report on the 8th Workshop on the Innovative Water Reactor for Flexible Fuel Cycle; February 10, 2005, Koku-kaikan, Minato-ku, Tokyo

Kobayashi, Noboru; Okubo, Tsutomu; Uchikawa, Sadao

JAERI-Review 2005-029, 119 Pages, 2005/09

JAERI-Review-2005-029.pdf:11.01MB

The research on Innovative Water Reactor for Flexible fuel cycle (FLWR) has been performed in JAERI for the development of future innovative reactors. The workshop on the FLWRs has been held every year since 1998 aiming at information exchange between JAERI and other organizations. The 8th workshop was held on Feb. 10, 2005 under the joint auspices of JAERI and North Kanto and Kanto-Koetsu branches of Atomic Energy Society of Japan with 75 participants. The workshop began with 3 presentations on FLWRs entitled "Framework and Status of Research and Development on FLWRs", "Long-Term Fuel Cycle Scenarios for Advanced Utilization of Plutonium from LWRs", and "Experiments on Characteristics on Hydrodynamics in Tight-Lattice Core". Then 3 lectures followed: "Development of Evaluation Method for Accuracy in Predicting Neutronics Characteristics of Tight-Lattice Core" by Osaka University, "Development of Cost-Reduced Low-Moderation Spectrum Boiling Water Reactor" by Toshiba Corporation and "Design and Analysis on Super-Critical Water Cooled Power Reactors" by Tokyo University.

Master plan and current status for feasibility study on thermal-hydraulic performance of reduced-moderation water reactors

Onuki, Akira; Takase, Kazuyuki; Kureta, Masatoshi*; Yoshida, Hiroyuki; Tamai, Hidesada; Liu, W.; Akimoto, Hajime

Proceedings of Japan-US Seminar on Two-Phase Flow Dynamics, p.317 - 325, 2004/12

We start R&D project to develop the predictable technology for thermal-hydraulic performance of Reduced-Moderation Water Reactor (RMWR) in collaboration with Power Company/reactor vendor/university since 2002. The RMWR can attain the favorable characteristics such as effective utilization of uranium resources, multiple recycling of plutonium, high burn-up and long operation cycle, based on matured BWR technologies. MOX fuel assemblies with tight lattice arrangement are used to increase the conversion ratio by reducing the moderation of neutron energy. Increasing the in-core void fraction also contributes to the reduction of neutron moderation. The confirmation of thermal-hydraulic feasibility is one of the most important R&D items for the RMWR because of the tight lattice configuration. In this paper, we will show the R&D plan and describe the current status on experimental and analytical studies. We will confirm the thermal-hydraulic performance in the tight-lattice bundles by this project and develop a predictable technology for the RMWR in future.

Investigation of water-vapor two-phase flow characteristics in a tight-lattice core by large scale numerical simulation, 1; Development of a direct analysis procedure on two-phase flow with an advanced interface tracking method

Yoshida, Hiroyuki; Nagayoshi, Takuji*; Ose, Yasuo*; Takase, Kazuyuki; Akimoto, Hajime

Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(3), p.233 - 241, 2004/09

https://doi.org/10.3327/taesj2002.3.233

When there are no experimental data such as the reduced-moderation water reactor (RMWR), therefore, it is very difficult to obtain highly precise predictions. The RMWR core adopts a hexagonal tight lattice arrangement with about 1 mm gap between adjacent fuel rods. In the core, there is no sufficient information about the effects of the gap spacing and grid spacer configuration on the flow characteristics. Thus, we start to develop a predictable technology for thermal-hydraulic performance of RMWR core using advanced numerical simulation technology. As part of this technology development, we are developing advanced interface tracking method to improve conservation of volume of fluid. In this paper, we describe a newly developed interface tracking method and examples of the numerical results. In the present results, the error of volume conservation in the bubbly flow is within 0.6%.

Designing of reduced-moderation water reactor and related development issues

Okubo, Tsutomu

Konsoryu, 17(3), p.228 - 235, 2003/09

The Reduced-Moderation Water Reactor is supposed to realize plutonium multiple recycling, and furthermore, plutonium breeding cycle, based on the well-established Light Water Reactor technologies. In the present paper, the overview of the design study is presented and the related R&D issues are introduced, especially focusing on the thermal hydraulic activities.

Study on gas-liquid two-phase flow distribution in a tight-lattice rod bundle

Onuki, Akira; Shibata, Mitsuhiko; Tamai, Hidesada; Akimoto, Hajime; Yamauchi, Toyoaki*; Mizokami, Shinya*

Nihon Konsoryu Gakkai Nenkai Koenkai 2003 Koen Rombunshu, p.35 - 36, 2003/07

Analytical evaluation of maximum critical power by so-called subchannnel code is indispensable for design of reduced moderation water reactor. In this study, two-phase flow distribution in a tight-lattice rod bundle is investigated using 19-rod bundle experimental rig and subchannnel analysis code NASCA. The flow distribution was measured under so-called churn flow regime and the predictive capability of NASCA was assessed. NASCA can predict the flow distribution qualitatively depending on local pressure drop. Quantitative prediction is also reasonable for liquid phase but the gas phase distribution was underestimated. Void-drift model has a dominant contribution and we should improve the model for the tight-lattice rod bundle.

Development of Reduced-Moderation Water Reactor (RMWR) for sustainable energy supply

Iwamura, Takamichi; Okubo, Tsutomu; Kureta, Masatoshi; Nakatsuka, Toru; Takeda, Renzo*; Yamamoto, Kazuhiko*

Proceedings of 13th Pacific Basin Nuclear Conference (PBNC 2002) (CD-ROM), 7 Pages, 2002/10

In order to ensure sustainable energy supply in Japan, the reduced-moderation water reactor (RMWR) has been developed by JAERI since 1998. MOX fuel assemblies with tight lattice arrangement are used to increase the conversion ratio. In order to establish negative void reactivity coefficient, the core should be short and flat to increase neutron leakage from the core. The core designs were accomplished to a large core with 1,356MWe and a small core with 330MWe. For both cores, negative void coefficient and natural circulation cooling of the core were realized. To confirm thermal-hydraulic feasibility, critical heat flux experiments were performed using 7-rod bundles with the gap width of 1mm and 1.3mm. The results indicated that enough cooling was assured for the tight lattice core. Further R&D studies, including large scale thermal-hydraulic experiments, reactor physics experiments, development of high burn-up fuel cladding material and simplified reprocessing technology, are necessary to realize commercial introduction of RMWR by 2020's for the replacement of current generation LWRs.

Critical heat flux and heat transfer above mixture level under high-pressure boil-off conditions for PWR type and tight-lattice type fuel bundles

Kumamaru, Hiroshige; Kukita, Yutaka

ANP 92: Proc. of the Int. Conf. on Design and Safety of Advanced Nuclear Power Plants,Vol. 3, p.24.4-1 - 24.4-7, 1992/00

no abstracts in English