Kazumi Ikeda

High level radio-active wastes reduction through fast reactor

Abstract The objective of this work is to investigate the characteristics and performance of some dedicated reactor core concepts in terms of the minor actinides (MA) and I-129 transmutation for reducing high level radio-active wastes. Reducing high level radio-active wastes is defined in this paper as follows; The radio-toxicity of long lived radioactive nuclides is reduced by transmutation of MA and I-129 in core. The volume of container for high level radio-active wastes is reduced. I-129 is transmuted because it is easy to solve in underground water and needs additional barrier to confine. Sr-90 and Cs-137 are stored in the facility to decay naturally before disposal. In the reference core arrangement of this study, MA are transmuted in core and I-129 is transmuted around the active core. The following three items on MA transmutation are investigated: the arrangement of MA, Pu and U in core with the negative Doppler constant and high transmutation rate, the application for Pu and MA from Mixed Oxide (MOX) spent fuel from LWR, and the comparison of core type and fuel types. As for I-129 transmutation, the application of moderator to enhance I-129 transmutation rate, the comparison of core type and the scenario of transmutation through irradiation are discussed.

Current Status and Development of Core Calculation Methodology for Sodium Cooled Fast Reactor in Mitsubishi

This paper presents current status and development of nuclear calculation methodology for sodium cooled fast reactor in Mitsubishi and two core design codes; an original two dimensional cell/lattice calculation code, PIJHEX and a thermal hydraulic calculation code, MIX-MKII. Mitsubishi Atomic Power Industries, Inc. developed several core design codes for Monju and JOYO and recently this activity continues still further for the next FBR in Japan. It is explained in this paper that the PIJHEX is confirmed to be valid from the comparison of Monte Carlo code and the examination on physical phenomenon in calculation results. Besides, the approach toward design and development of code system in Mitsubishi and MIX-MKII are introduced briefly.Copyright

Study on core concept for commercial LMFBR plant toward self-consistent nuclear energy system concept

Abstract Fast Breeder Reactor (FBR) is expected to be commercialized in Japan to overcome foreseeable problems such as reactor safety, increasing energy demand, final disposal of high level radioactive waste and fuel resource shortage. We have been studying three FBR core concepts enhancing its potential abilities; ultra-large type, simplified type and friendly to fuel cycle type core. This study is sponsored by Ministry of International Trade and Industry.

Advanced Recycling Reactor Design Study

The Advanced Recycling Reactor (ARR) design study sponsored by DOE of USA has been conducted [1]. This paper presents the pre-conceptual design of the ARR that is a loop-typed sodium cooled reactor with MOX fuel. The International Nuclear Recycling Alliance (INRA) takes advantage of international experience and agreed to use Japan Sodium-cooled Fast Reactor (JSFR) [2] as reference for Funding Opportunity Announcement (FOA) studies [1]. Since the scale-up factor of two is acceptable increase from manufacturing and licensing points of view, INRA proposes 3 evolutions of the ARR; ARR1, a 500 MWe demonstration plant, online in 2025; ARR2, a 1,000 MWe commercial plant, online in 2035; ARR3, a 1,500 MWe full-scale commercial plant, online in 2050. Japan has conducted R&Ds for the JSFR incorporating thirteen technology enhancements expected to improve safety, enhance economics, and increase reactor reliability. The ARR design is based on such the technology enhancements that it can benefit from this development effort and the ARR3 can become cost competitive with the similar sized LWRs. Major features of key technology enhancements are the following: Decay heat can be removed by natural circulation to improve safety. The primary cooling system consists of two-loop system and the integrated IHX/Pump to improve economics. The steam generator with the straight double-walled tube is used to improve reliability. The reactor core of the ARR1 is 70 cm high. The conversion ratio of fissile is set up less than 0.6 and the amount of burned TRU is 45–51 kg/TWeh. The ARR1 consists of a reactor building (including reactor auxiliary facilities and electrical / control systems), a turbine building, and a reprocessing building. The dimensions of the overall reactor building will be 46.1 m (W) × 72.8 m (L) × 70.3 m (H), and the volume of the building will be approximately 180,000 m3 .Copyright