Yorikata Mizokami

Cost and performance design approach for GTHTR300 power conversion system

Japan Atomic Energy Research Institute (JAERI) has been carrying out a design and developmental program for the gas turbine high temperature reactor of 300 MWe nominal-capacity (GTHTR300) power plant, aiming at prototype demonstration in Japan during 2010s. This paper introduces overall objectives of the program and describes the plant design and development approach taken to achieve these goals. A detailed description is focused on the power conversion system design and associated component research and development undertaken in the present program. The power conversion system incorporates unique design approach of non-intercooled cycle to attain economical performance at minimal system complexity, intrinsic cycle flow provision for reactor pressure vessel cooling, simplified and high-performance turbomachine in a horizontal design, and modularity of maintenance for all major power conversion equipment. This paper reports extensive technical evaluation related to these significant system design features, which are shown to offer the optimum solution of plant cost, efficiency potential, reliability and maintainability in addition to near-term commercial deployment.

A Study on an Evaluation of Indirect Cycle Plant Systems for HTGR

In the world now, several types of indirect system concept have been investigated for the High Temperature Gas cooled Reactor power plant (HTGR). From a point of optimization of HTGR, it is important to investigate and to compare their power conversion systems from a technical and an economical view point. In the first step of this study, an indirect steam cycle (ID-SC), an indirect gas turbine cycle (ID-GT), an indirect gas turbine combined cycle (ID-CCGT) and a direct gas turbine cycle (D-GT) has been chosen as the systems to be compared. The followings are chosen items for comparison analysis: a) Plant efficiency; b) Amount of commodities (which can estimate capital cost); c) Flexibility of reactor core design; d) Technical issues to be developed; e) Compatibility with hydrogen production system, etc. And for the second step, as the system optimization study among the selected system, sensitiveness to plant efficiency by changing the inlet and the outlet temperature of reactor core has been investigated from an economical and plant efficiency point of view.© 2008 ASME

Inelastic deformation and creep-fatigue life of plate-fin structures

The equivalent-homogeneous-solid concept, i.e., the homogenization approach, is often applied to inelastic analysis and creep-fatigue life prediction for plate-fin heat exchangers such as those used in high-temperature gas cooled reactors. The applicability of this approach to actual plate-fin structures manufactured by means of brazing still remains to be clarified. Firstly in this paper, basic features of the inelastic behavior of ultra-fine plate-fin structures with offset were numerically clarified by homogenization FEM analysis for a unit cell model. Secondly, considering the weakest loading direction, uniaxial tensile, creep and creep-fatigue tests on small-size plate-fin structures made of SUS316 were carried out at 600 \(^\circ \)C. Lastly, thermal fatigue tests using the partial model of heat exchangers were performed under cyclic loading of temperature distribution. The results obtained can be summarized as follows. The macroscopic stress-strain behavior and macroscopic strength of plate-fin structures were successfully predicted by the homogenization approach. Fatigue failure, on the other hand, is sensitive to local structures such as the brazing filler metal shape in plate-fins, and experiments are necessary to obtain the fatigue strength reduction of plate-fin structures. Thermal fatigue life prediction based on anisotropic elastic-plastic FEM analysis yielded good results showing predicted life of 2,100 cycles, or 60 % of the observed life, thus within a factor of 2.

Development of Plant Dynamics Analysis Code for HTGR-Steam Cycle

A control and operation method of a High Temperature Gas Cooled Reactor (HTGR) power plant with Steam Cycle has been investigated, and an adequacy of the method has been examined by plant dynamics analyses. In this plant, the steam cycle system with regenerative and reheat cycle is employed, where the heat generated in the reactor is transferred to the secondary coolant (water and steam) through the steam generator (SG), which has the steam turbine and generator, is installed in the secondary system. The reactor and steam cycle system control methods were evaluated. Analytical results through system modeling concluded that the reactor power changes could be effectively achieved by utilizing primary system helium flow rate control, and overall plant system responsiveness and control could be achieved by employing feed water flow control system and turbine governor control system. The plant dynamics analysis code ASURA, which was developed by MHI, can simulate the major components and systems of this plant. It was used for this examination. In order to adequate of the control and operation method, some cases of plant dynamics analysis by ASURA was conducted in this study.Copyright

Description of Inelastic Behavior of Perforated Plates Based on Effective Stress Concept

High-temperature heat exchangers are well known as important components of high-temperature nuclear reactors such as High-Temperature Gas-Cooled Reactors and Fast Breeder Reactors. Perforated plates in heat exchanges are one of the critical parts from a viewpoint of creep-fatigue damage.

The Mitsubishi Small Module High Temperature Gas-Cooled Reactor “MHR-50/100is” — Present Design Status and Its Prospect for Commercialization

Mitsubishi Heavy Industries, Ltd. (MHI) has been carrying on development of a SMR for global strategic business and a conceptual design study of HTGR, namely MHR-50/100is having a high inherent safety and a high economical advantage for commercialization with supporting by Japan Atomic Energy Agency (JAEA). To begin with, a design philosophy of the MHR-50/100is had been set and the next phase, a conceptual design including plant dynamics analysis to investigate operational function and plant controllable performance had been carried out. It has been improved to establish higher safety level to meet the safety requirements after TEPCO’s Fukushima Daiichi Accident on March 11, 2011 in Japan.A market research and a financial analysis to review a feasibility of nuclear business have been studied. Consequently, it has concluded that the large market and the business potential will be prospected. We envisioned that it is effective for acceleration of MHR-50/100is utilization to show wider application of the nuclear energy in general industry as well as electricity generation. In the study cooperative with these users, we have studied on a practical applicability of MHR-50/100is in a typical general industry. A concept of the heat utilization plant consisting of the MHR-50/100is and hydrogen production plant has been developed; a safety concern has been evaluated. This paper reports a summary of a series of the conceptual design studies, and the various evaluation analyses in which we investigated a technical feasibility and a business potential of MHR-50/100is.Copyright