Isao Minatsuki

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.

Improvement in the Design of Helium Turbine for the HTGR-GT Power Plant

This paper describes the conceptual design of a 600MW HTGR-GT power plant which has been completed in the framework of the HTGR-GT feasibility study project. The project is assigned to JAERI by the Science and Technology Agency in Japan. The inlet and outlet gas temperatures in the reactor are 460°C and 850°C, respectively. Helium gas pressure is 6MPa. The gas turbine system type is intercooled recuperative direct cycle. Designs of helium turbine, LP and HP compressors and generator are presented. Efforts have been focussed on reducing their dimensions and weight in the preliminary design to facilitate the mechanical design of the rotor and also reduce the size of power conversion vessel. Rotor dynamics behavior and maintenance procedures of the horizontal single-shaft configuration adopted are explained.Copyright

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

Environmentally-Friendly HTGR: MHR-50/100—Concept and Characteristics

A business plan and a new concept of the Mitsubishi small-sized High temperature gas-cooled modular Reactors (MHR-50/100) had been developed as reported in a paper at the HTR-2010 conference in Prague. The present paper reports the results of ensuing conceptual design study including updated market researches, improved safety features of the plant, and the plant dynamics analysis. Market researches on Japan, the USA, Southeast Asia and the Middle East have been updated applying the latest energy outlook data. The result shows that the potential market share for the type of HTGR (high temperature gas reactor) reactors is expected to be 10–20% in new construction of heat source plants in those market areas. A financial analysis made based on the results of the updated market research and the plant cost evaluations indicates that the feasibility of an HTGR business potentially exists. Concerning about the conceptual design, as main themes of the study, a plant design, safety design and plant dynamics have been carried out. The MHR-50/100 high safety characteristics have been confirmed based on the results of the following studies as reported in the present paper: (1) An investigation of a safety scenario during occurrence of a Total Black Out event; (2) An analysis of the reactor decay heat removal via a natural circulation. Lastly, the control methods for the reactor and associated steam cycle system for the MHR-50 have been studied. The results show that the reactor power changes can be effectively achieved by controlling the primary system helium flow rate. The ASURA code developed by MHI is used for simulation of such typical plant transients as 10% step load reduction and full load rejection. The results confirm the easy operability and controllability of the plant.Copyright

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

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

A study of a new electrical energy storage system in which nuclear energy is used for methanol production

Abstract The significance of nuclear energy is increasing because it has the potential to solve a number of problems concerned with shortages of fuels and environmental degradation in the 21st century. Therefore the uses of nuclear power should be widened so that it can be used as a source of heat energy as well as just being used for electrical generation. A concept for utilizing nuclear energy effectively has been studied for an electric power company. A new electric energy storage system has been proposed which stores power by producing a synthetic fuel, methanol. The methanol is made from coal gas and hydrogen which is produced by excess off-peak electricity and high temperature heat from a HTGR. The system is not only technically feasible, but is also cost-competitive with other storage systems.