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Yukio HISHINUMA, Takemi CHIKAHISA, Kei KAWAKAMI
Article type: Article
Pages
195-196
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The paper analyzes the optimum cogeneration system (CGS) for the reduction of green house gases and cost. Comparison was made for the cases with heat storage system and possibility of power grid connection. The result shows power grid connection of houses is essential for the reduction of green house gases. Heat storage is effective for reduction of cost and for cooperative operation of CGS with power grid. The paper proposes a CGS of combined house-office cluster, which is connected to the power grid, as a effective system for the reduction of green house gas and cost.
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Norio ARAI, Kunihiko MOURI, Tomohiko FURUHATA
Article type: Article
Pages
197-198
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The new concept that several local energy networks including distributed power generations such as micro gas turbine and fuel cell are integrated and controlled by means of the Internet technologies is proposed to operate the distributed power generation systems in high efficiency. In this paper, the possibility and advantage in costs of Line Power Supply concept which is the base of our new energy network concept are discussed. The infrastructure for railroad power supply is utilized in the Line Power Supply concept. Moreover, the advantage of the integrated local energy network concept to which the Line Power Supply concept is applied is described.
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Yoshinori HISAZUMI, Terushige FUJII, Kazumi TANIMOTO, Kunihiko MOURI
Article type: Article
Pages
199-200
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Neighboring Co-Generation (NCG) System is created to present the comfortable and high quality living environment, using combined power and heat (CHP) technologies. The key concept of this system is to connect the home and home for one loop of heat transfer line and level or manage the demand of heat consumption in the small community with high internet practice. This system is expected to optimum the heat utilization and to aim the higher efficiency than stand alone of the distributed generation system. And further expectation for the system is that this system will contribute to save energy, which is equivalent to abate over 50% of CO2 emission from homes due to the higher efficiency of CHP. In urban area of Kinki area, approximate 55% inhabitants live in condominium. Then introduction of the system will be expected to be able to cntribute to achieve CO2 abatement target for the Kyoto protocol. This system will also increase the availability of the co-generation system and improve the heat use management. For the realization of this system, the study group is established in AIST Kansai Center recently and the combination technologies of heat supply, heat storage and air conditioning are under development besides the Information Technologies (IT) application. This paper describes the new idea of energy supply system with participation of inhabitants for the energy network system.
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Takehiro HIMENO, Akira KONNO, Toshinori WATANABE
Article type: Article
Pages
201-202
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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On the occasion of the first flight of H-IIA launch vehicle (TF#1), the dynamic motion of liquid hydrogen aboard the upper stage was observed with a CCD camera. The visualized images and the other outputs from the sensors indicated that the injected gas for the pressurization penetrated deeply into the liquid phase under low-gravity condition during the coasting flight before the second ignition (SEIG2). To avoid the gas penetration in the second flight (F#2), the configuration of the diffuser, which introduce the pressurized gas into the tank, was modified and its performance was both experimentally and numerically investigated in advance. To grasp the detail of liquid motion driven by the injected gas, the flow field including free-surface was simulated with newly developed code, called CIP-LSM. In the computation, the gas penetration was successfully reproduced with the old diffuser and the improved performance of the modified diffuser was also confirmed
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Osamu Kawanami, Toshihiko Hiejima, Hisao Azama, Haruhiko Ohta, Ryoji I ...
Article type: Article
Pages
203-204
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In a future space infrastructure based on Orbit Transfer Vehicle, resupply technology of cryogenic fluid, especially heat management technology will be of importance. Our study is on forced convective boiling of cryogenic fluid (NL_2 as used) under microgravity. In the present experiments, we used a transparent heating tube, whcih can allow simultaneous temperature measuremnts and visual recordings. They were conducted under microgravity using Japan Microgravity Center as well as under 1G. We succeeded in measuring both heat transfer and quench front speed at the same time. Quench front speed under microgravity was about 1.2 times larger than under 1G for the same average mass velocity. As a result, heat transfer of cryogenic flow boiling is promoted under microgravity. Finally, outline of experimental project, which will be conducted by the author's group, is presented.
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Norihiro FUKAMACHI, Tatsuya HAZUKU, Tomoji TAKAMASA, Takashi HIBIKI, M ...
Article type: Article
Pages
205-206
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Axial developments of one-dimensional void fraction, bubble number density, interfacial area concentration, and Sauter mean diameter of adiabatic nitrogen-water bubbly flows in a 9-mm-diameter pipe were measured under a microgravity environment using an image-processing method. The interfacial area transport mechanism was determined based on visual observation. Marked bubble coalescence occurred when fast-moving bubbles near the channel center overtook and swept up slower-moving bubbles in the vicinity of the channel wall (velocity profile entrainment). Negligible bubble breakup was observed because of weak turbulence under tested flow conditions. Axial changes of measured interfacial area concentrations were compared with the interfacial area transport equation considering the bubble expansion and wake entrainment as observed under a normal gravity environment. The velocity profile entrainment effect under microgravity was likely to be comparable to the wake entrainment effect under normal gravity in the tested flow conditions. This apparently led to insignificant differences between measured interfacial area concentrations and those predicted by the interfacial area transport equation with the wake entrainment model under normal gravity.
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Buhong CHOI, Terushige FUJII, Hitoshi ASANO, Katsumi SUGIMOTO
Article type: Article
Pages
207-208
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In order to investigate the flow and hydrodynamic characteristics of two-phase flow influenced by the change in gravity, tests were performed using MU-300 flight capable of producing μg and 2g conditions and on ground with the identical flow conditions and the same flow loop. The test section was a 10mm diameter and 600mm lengths, and it was also mounted horizontally to the direction of gravitational force. The ranges of superficial velocity are 0.1m/s to 2.6m/s for water, 0.03m/s to 21m/s for air, respectively. The data collected at three gravity levels (μg, 1g and 2g) were compared with the existing models and correlations, and the differences and similarities between the two-phase flow characteristics at three gravity levels were also presented.
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Shuang Ye, Terushige Fujii, Hitoshi Asano, Katsumi Sugimoto
Article type: Article
Pages
209-210
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Gas and liquid phases are easily separated owing to buoyancy on the ground. However, in space (i.e. under micro-gravity condition), the method cannot be adopted. Many methods were proposed such as utilizing centrifugal force, capillary force and surface tension. But it is estimated to be difficult to apply to convective two-phase flows with high flow rate due to the low capacity. In this study, a method of a Y-junction by using the difference of inertia force between gas and liquid phases is proposed for a first-step and rough separation.
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Akihiro NAKANO, Tetsuo MUNAKATA
Article type: Article
Pages
211-212
Published: September 20, 2002
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Near feature, cryogenic propellants including liquid hydrogen, liquid oxygen and liquid natural gas will be handled on orbit for space transportation systems. It will be absolutely needed to measure the liquid volume under the micro-gravity condition. In the present study, Helmholtz resonance is applied to measure a liquid volume. In order to confirm the applicability of this measurement technique to cryogens, the micro-gravity experiment using liquid nitrogen was carried out. We report the experimental results and propose a measurement system for the practical application on orbit.
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Atsushi BABA, Naoki MIYAGI, Koji MIYAZAKI
Article type: Article
Pages
213-214
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This paper describes the development of small-sized mechanical pump. The pump can be used in thermal control system, like as mechanical pump loops, of future spacecraft. Three main design features of this pump are; 1) Ammonia is the working fluid. It has a very low viscosity and it is the best coolant for space application. 2) The pump is very small-sized and lightweight, which is highly desired for space applications. 3) Amorphous carbon is used for the inner and outer gears and bearings of the pump. The pump's external diameter is 48mm and thickness is 15.6mm. At 4000the rpm gear speed, the maximum flow rate for the ammonia is about 0.5 liter per minute. Miniaturization was achieved by using bearings made from amorphous carbon and using an axial type motor instead of a radial type motor. Future applications of this pump include not only space applications, but also medical instruments, and cooling systems for high heat generating computers and electronic devices.
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Atsushi OKAMOTO, Atsushi BABA, Shogo KOKUBO, Toshiyuki SUZUKI, Haruo K ...
Article type: Article
Pages
215-216
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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To clarify the mechanisms of boiling heat transfer and two-phase flow under microgravity conditions, the development of a compact two-phase flow loop, which meets the requirement for NASDA FPEF (Fluid Physics Experiment Facility) in ISS (International Space Station), is attempted. The present paper describes the expected problems in the design of the loop and its components under the restrictions inherent in the facility. Flow boiling experiments in tubes and in a duct with a large cross section are planned, and the latter allows the phenomena near pool boiling if mass velocity is very small. To observe behaviors of microlayer underneath an attached bubble, which gives information about the mechanisms of nucleate boiling heat transfer, the development of a new heating surface is planned to control locally the heating conditions and to measure local heat transfer characteristics by using thin micro-heaters coated directly on a transparent surface. To reduce the electric power supply, heat recovery system is to be introduced in the test loop, where a part of heat removed from a condenser is supplied to preheaters requiring large power to realize prescribed qualities in the tube test sections. Since the restriction of volume is one of serious problems preventing the use of long heated tubes, the validity of a short tube for the measurement of two-phase forced convective heat transfer is investigated.
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Haruaki Itagaki, Hiroshi Miura, Takaaki Yokoyama, Shunichi Okaya, Masa ...
Article type: Article
Pages
217-218
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Solar energy is available in daytime mission on the moon, but other energy sources are required at night mission, where day and night are repeated every 30 days. A regenerative fuel cell system is selected as the energy source of lunar mission. In the regenerative fuel cell system, hydrogen and oxygen gas are generated by excess power at daytime using electrical decomposition of water. On the other hand hydrogen and oxygen gas are transformed to water by fuel cell, and then electrical power is generated. In this paper, configuration and feasibility of regenerative fuel cell system for energy source of lunar mission is studied. The feasibility is also confirmed by basic experiment.
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Kouichi Chino, Nobuhiro Sugesawa, Eiichi Koda, Masahiro Matsubayashi
Article type: Article
Pages
219-220
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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An energy storage system using liquid air is studied. Liquid air is produced by off-peak power and LNG cold heat, and can be stored at atmosphere pressure. When on-peak power is needed, the stored liquid air is pumped to high pressure and fed to the combustor of a gas turbine. Cold heat energy of liquid air at day time is stored and reused to generate liquid air at night. When the system is applied to LNG base on the condition of 50 ton/h LNG flow rate, the power storage efficiency is found to exceed 70%.
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Kazuaki KITOU, Kouji SHIINA, Kouichi CHINO
Article type: Article
Pages
221-222
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The cool storage material composition of the concrete-type cool storage unit used for the LNG cold heat energy utilization system was determined from the viewpoint of thermal performance. The blending composition for cool storage material was selected as Portland blast furnace cement + sand + air entraining low-water agent + steel fiber. Thermal conductivity was about 20% higher than regular concrete and stainless steel fiber concrete. The liquefaction was examined for conditions assuming an actual plant with the concrete-type cool storage unit. With sufficient insulation treatment, the prospect was good for a stable liquefaction rate of 80% or more.
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Kazuaki KITOU, Kouji SHIINA, Kouichi CHINO
Article type: Article
Pages
223-224
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The structural integrity of the concrete cool storage unit used for a LNG cool heat energy utilization system was evaluated. The strength of the selected concrete composition for the cool storage material was about 2.5 times higher than that of regular concrete by using air entraining low-water agent and steel fiber. The strength did not deteriorate after 1000 low temperature heat cycles. Moreover, a structure analysis was carried out with using actual plant parameters. Nearly all of the stress given to the concrete cool storage material was less than the allowable stress, and it was confirmed that the integrity of the concrete cool storage unit was maintained.
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Hidefumi ARAKI, Mitsugu NAKABARU, Kooichi CHINO
Article type: Article
Pages
225-226
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Two types of heat exchangers that exchange heat between air and combustible LNG were investigated. Heat transfer and pressure drop characteristics of these heat exchangers were measured under moist air conditions to know the effects of frost formation. The experimental result showed that the air side pressure drop at the downstream heat exchanger didn't increase when moist air was cooled below 223K by the upstream heat exchanger. Double-tube type heat exchanger is the more suitable for the upstream heat exchanger from a viewpoint of the rate of increase in pressure drop, while Plate-fin type heat exchanger requires a smaller space for the downstream heat exchanger below 223K. By combining these two heat exchanger types, a heat exchanger system is proposed, which cools 108 t/h of air below 130K with the pressure drop less than 30kPa within a space of 105m^2.
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Yasuo Koizumi, Masanori Tsukudo, Hiroyasu Ohtake
Article type: Article
Pages
227-228
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Quenching of a thin-gap annular flow passage; δ=0.3∿5.0mm, by gravitational liquid penetration was examined experimentally by using R-113. The quenching was observed for the gap spacing over 1.0mm. When the spacing was less than 1.0mm, the wall was gradually and monotonously cooled down without any quenching. The peak heat flux during the quenching process was much lower than that in pool boiling and considerably decreased as the gap spacing became narrow. The surface area covered by liquid during the film boiling period decreased as the gap spacing became narrow, which corresponded well with the decrease of the peak heat flux with gap spacing decrease.
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Noriyoshi WADA, Hiroyasu OHTAKE, Yasuo KOIZUMI
Article type: Article
Pages
229-230
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The onset nucleate boiling and the point net vapor generation on subcooled flow boiling, focusing on liquid subcooling and liquid velocity were investigated experimentally and analytically. Experiments were conducted using a copper thin-film (35μm) and subcooled water in a range of the liquid velocity from 0.27 to 4.6m/s at 0.10MPa. The liquid subcoolings were 20,30 and 40K, respectively. Temperatures at the onset nucleate boiling obtained in the experiments increased with the liquid subcoolings and the liquid velocities. The increase in the temperature o* ONB was represented with the classical stability theory of preexisted nuclei. The measured results of the net vapor generation agreed well with the results of correlation by Saha and Zuber in the range of the present experiments. The temperature at the ONB decreased with increasing the size of surface roughness. The NVG was independent on the surface roughness.
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Tatsuya KOGA, Tomoji TAKAMASA, Akira SAITO
Article type: Article
Pages
231-232
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In a wall-crack accident or loss-of-coolant accident (LOCA) in an advanced reactor with water-filled containment, high-pressure saturated water is discharged from the pressure vessel into the low-pressure, low-temperature water of the containment. The discharged saturated water causes flashing and generates steam. Steam is then condensed by the water in the containment. Our previous study of high-pressure saturated water that rapidly contacts low-pressure, low-temperature water, revealed that flashing of high-pressure saturated water and a subsequent water hammer occurred under the specified experimental settings. Pressure peaked when steam generation or flashing occurred at the wall surface and the flashing steam condensed. After the peak, pressure oscillated and reached equilibrium condition in a short time. To check the results of the experiments, numerical analysis was conducted using bubble growth theory in this study.
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Hironori WATANABE, Tadashi IGUCHI, Mamoru KIMURA
Article type: Article
Pages
233-234
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Conductance-type void fraction meter is a practical void fraction meter. It can apply to various test section (Round flow path, rectangular flow path, and rod bundle with squire lattice or triangular lattice). The principle of the meter is based on the fact that the electrical conductance changes with the change of void fraction in gas-liquid two-phase flow. According to air/water two-phase flow experiment, it was confirmed that void fraction α could be obtained by measuring I/Io (Io is current at α=0). The relation between α and I/Io agreed with Maxwell's equation. The void fraction meter can be applied to high temperature/high pressure condition (290℃, 7MPa), by taking account of temperature dependency of water specific conductance. It was succeeded to measure the void fraction of steam/water two-phase mixture in 2×2 bundle flow path in the range of 0%-60% under high temperature/high pressure condition.
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Tadashi IGUCHI, Yasuteru SHIBAMOTO, Hideaki ASAKA, Hideo NAKAMURA
Article type: Article
Pages
235-236
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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It is known that the heater rod temperature changes periodically up and down under BWR instability condition, indicating the periodic occurrence of the boiling transition and rewetting due to the flow oscillation. When the heater power was increased further, the rod temperature was kept higher, indicating that the heat transfer mode changed to the continuous film boiling without rewetting. The power at the onset of the continuous film boiling under flow oscillation was depending on the flow amplitude and was lower than that under the stable condition. This was considered due to the delay of the rewetting against the flow rate recovery.
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Yosiaki TSUKUDA, Norio KONO, Yoshiei AKIYAMA, Keiichi HORI, Takayuki S ...
Article type: Article
Pages
237-238
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In the thermal-hydraulic design of Pressurized Water Reactor, the departure from nucleate boiling (DNB) under the anticipated transients is not allowed. However, it is recognized that DNB dose not cause the fuel rod failure if the fuel rod temperature after DNB is not so high and the film boiling duration time is not so long. To establish the evaluation method of the heat transfer behavior after DNB, the post-DNB heat transfer experiments for PWR fuel assemblies were performed under the sponsorship of Ministry of Economy, Trade and Industry (METI). Based on the obtained experimental data, the post-DNB heat-transfer correlation, the model of the axial propagation of the film-boiling region after DNB and the model of the rewet front progress were investigated.
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Kazuhiko YAMAMOTO, Rumi SHIMADA, Hideo NAKAMURA, Masaya KONDO, Kenji A ...
Article type: Article
Pages
239-240
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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A series of fundamental heat transfer tests using a horizontal U-shaped condenser tube were performed to estimate the characteristics of a horizontal heat exchanger for a passive containment cooling system (PCCS). This paper summarizes new correlations to predict non-condensable gas effects on heat transfer and annular condensation heat transfer taking the roll-wave stirring effect into consideration.
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Toru NAKATSUKA, Masatoshi KURETA, Tsutomu OKUBO, Hajime AKIMOTO, Takam ...
Article type: Article
Pages
241-242
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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It is important to evaluate the thermal margin of the Reduced-Moderation Water Reactor which consists of tight lattice fuel assemblies with gap clearance around 1.0mm. Subchannel analyses may provide valuable information to supplement thermal hydraulic experiments. To assess the applicability of subchannel analysis for tight lattice cores, critical heat flux experiments for tight lattice cores were analyzed with COBRA-TF code. The test section was a 7-rod bundle with rod diameter of 12.3 mm, rod gap of 1.0 mm and heated length of 1.8 m. It was found that COBRA-TF gives good prediction of critical power for mass velocity of 400-500kg/(m^2s), while it underestimates the critical power for lower mass velocity and overestimates for higher mass velocity. With modification of interfacial heat transfer model, the difference between measured and predicted powers in the high mass velocity region was reduced.
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Yasushi YAMAMOTO, Nobuaki ABE, Shinichi MOROOKA, Kouji HIRAIWA
Article type: Article
Pages
243-244
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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A new fuel assembly design with tightened fuel rod has been proposed to achieve high conversion ratio about 1 on Boiling Water Reactor. The steady and transient critical power performance of the tight lattice rod bundle had not been known sufficiently in spite of important items for evaluating the possibility of BWR core with high conversion ratio. Therefore, the critical power measurement tests for tight lattice rod bundle have been performed under BWR steady and transient conditions. As that result, it was found that Arai CHF correlation had enough ability for predicting the steady-state critical power and transient dryout time for tight lattice BWR rod bundle.
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Yoshiaki MAKIHARA, Akimi SERIZAWA, Tomoaki KUNUGU, Tetsuo MATSUMURA, I ...
Article type: Article
Pages
245-246
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The primary strategy in the development of small-scale reactors is to construct a new design concept which satisfies the requirements of enhanced safety, capital cost reduction and proliferation resistance. For this goal, a reactor vessel with an integrated primary system configuration is chosen as the most optimum reactor configuration in the present work. This configuration adopts natural circulation and self-pressurization systems, which eliminate pressurizer, reactor coolant pumps and all loop pipings. In addition to these basic designs, the innovative technologies of Hybrid Heat Transport System (HHTS) and Stand-alone Direct Heat Removal System (SDHS) have been developed to improve economy and safety. This plant is named as Integrated Modular water Reactor (IMR).
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Mitsuru KAMBE, Hirokazu TSUNODA, Kaichiro MISHIMA, Takamichi IWAMURA
Article type: Article
Pages
247-248
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The 200 kWe uranium-nitride fueled lithium cooled operator-free reactor RAPID-L has been established. The reactor has no control rod, but involves the following innovative reactivity control systems : Lithium Expansion Modules (LEM) for inherent reactivity feedback, Lithium Injection Modules (LIM) for inherent ultimate shutdown, and Lithium Release Modules (LRM) for automated reactor startup. All these systems adopt lithium-6 as a liquid poison instead of B_4C rods. In combination with LEMs, LIMs and LRMs, RAPID-L can be operated without operator. Transient characteristics by plant dynamics analyses are demonstrated in this paper.
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Hiroyuki KOGAWA, Masatoshi FUTAKAWA, Shuichi ISHIKURA, Ryutaro HINO, K ...
Article type: Article
Pages
249-250
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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A mercury target vessel will be subjected to pressure wave generated by rapid thermal expansion of mercury due to pulsed proton beam injection. The pressure wave will propagate from the liquid mercury to the vessel (solid metal). The pressure wave may induce cavitation on the interface between the vessel and the liquid mercury due to coupled behavior between the pressure waves and deformation of the vessel. In order to investigate the cavitation damage due to coupled behavior, we have carried out impact tests on the mercury by using a modified conventional split Hopkinson pressure bar apparatus. Test pieces with 16 mm diameter and 5 mm thickness; A6061-T6,316LSS, Inconel600 Maraging steel and CrN coating on 316LSS, were set on the ends of both bars contacting the mercury. Many pits were observed on the specimen surface. The ranking order of cavitation damage is A6061-T6>316LSS ≅Inconel600>Maraging steel, which is the same order as the hardness of materials. The harder material such as CrN coating on 316LSS was not damaged.
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Masanori KAMINAGA, Katsuhiro HAGA, Tomokazu ASO, Hidetaka KINOSHITA, H ...
Article type: Article
Pages
251-252
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The Japan Atomic Energy Researc Institute (JAERI) and the High Energy Accelerator Research Organization (KEK) are promoting a project to construct a neutron scattering facility at the Tokai Research Establishment, JAERI, under the High-Intensity Proton Accelerator Project (the JAERI/KEK Joint Project). In the facility, 1 MW pulsed proton beam (3GeV, 0.333mA, 25Hz) from a high-intensity proton accelerator will be injected into a mercury target in order to produce high-intensity neutrons. A cross flow type (CFT) mercury target has been designed in order to distribute mercury flow according to an axial heat generation distribution caused by spallation reaction. The maximum mercury temperature in the CFT target and maximum target vessel temperature were calculated to be 104℃ and 149℃, respectively, under conditions of the inlet temperature 50℃ and mercury flow rate 40.7m^3/h. These results show that each value was less than the maximum design temperature of 200℃. Furthermore, maximum stress appeared in the target vessel, which was a sum of stresses caused by inner pressure, temperature differences between inner and outer vessel, pulsed pressure wave, was calculated less than the allowable design stress of 345 MPa.
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Keisuke Kawakita, Nobuyuki Takenaka, Daiki Akie
Article type: Article
Pages
253-254
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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High energy proton beam is irradiated to the target made of high atomic number material to initiate nuclear spallation reaction. The nuclear source is used in the experiments of neutron scattering and neutron radiography. The neutron production efficiency decrease due to the intense of increase of the coolant ratio to solid target metal when the proton beam intensity is high. A liquid metal target is effective to solve this problem. In this study, mercury was used as a working fluid in a tube heated by direct electrical current in similar situation as an actual target, and were verified the effects of mercury wettability to the inner surface of the tube on forced convective heat transfer.
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Yoshihiro KIKUCHI, Koji KUWAHARA, Motohide SHIMIZU
Article type: Article
Pages
255-256
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Numerical experiments have been conducted to verify a computer aided temperature measuring system for real time prediction of fluid temperature from outer surface of the cooling pipe of Liquid Metal Cooled Reactor. The working fluid is sodium. Unsteady two-dimensional calculations are first carried out to investigate conjugated convection-conduction heat transfer in a parallel-plate flow duct of stainless steel wall. Calculated temperatures of the outer surface are then used as input data for predicting the temperature of heat transfer surface by one-dimensional inverse heat conduction method. Bulk temperature of fluid is finally obtained from the temperature of heat transfer surface by means of a correlation equation of steady heat transfer coefficient. Predicted results are in good agreement with true values of fluid temperature.
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Masahiro FURUYA, Izumi KINOSHITA
Article type: Article
Pages
257-258
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The triggering process of vapor explosion was visualized by high-speed digital video cameras at an interface between a water droplet and a molten tin pool. A cluster of bubble generated by spontaneous bubble-nucleation covered the whole contact area at 0.10ms after the impingement. Prominent fine mixing between two liquids were found to start at 0.55ms that resulting in vapor explosion. A water micro jet toward the molten tin surface might induce the fine mixing after the bubbles had expanded excessively and had contacted the subcooled water.
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Hiroshi SEKIMOTO, Shinichi MAKINO
Article type: Article
Pages
259-260
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Lead bismuth eutectic (LBE) shows a good performance on neutron economy, and LEB cooled fast reactor can be designed as an excellent long-life small reactor. LEB is good not only for neutron economy but for chemical inertness and high boiling point, which may realize a much safer reactor than conventional sodium-cooled reactor. We have designed such a long-life small reactor and name it LSPR, whose total power is 150MWt (53MWe). During whole reactor life of 12 years the excess reactivity required for burnup is very low, and negative coolant dilatation coefficient is confirmed. This paper presents safety performances of LSPR at severe accidents
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Takaaki SAKAI, Yasuhiro ENUMA, Takashi IWASAKI
Article type: Article
Pages
261-262
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This paper describes numerical analysis for a Lead-Bismuth eutectic (LBE) cooled natural circulation fast reactor. A transient analysis for the un-protected loss of heat sink (ULOHS) condition has been performed by the combined multi-dimensional plant analysis code (MSG-COPD). As a result, thermal-stratification phenomenon has been observed in the lower-plenum of the reactor vessel during the transient. It has become clear that the thermal-stratification should be prevented in a LBE-cooled natural circulation reactor's design.
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Kei ITO, Takaaki SAKAI
Article type: Article
Pages
263-264
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Lead-bismuth eutectic (LBE) has a corrosiveness for structural materials. Oxygen concentration control in the eutectic plays an important role on the corrosion protection. In this paper, Development of concentration diffusion analysis code (COCOA : COncentration COntrol Analysis code), and the calculation results are described for a LBE-cooled natural-circulation reactor. Calculation was carried out by two control method (ON-OFF control and PID control). It was calculated even when a trouble occurs in the oxygen control system. As a result, it is concluded that both control methods can control oxygen concentration successfully in the natural circulation reactor. In addition, concentration control is possible even when a trouble occurs in the hydrogen supply system.
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Fumiaki YAMADA, Akira ONOUE
Article type: Article
Pages
265-266
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The availability factor of lead-bismuth cooled reactor was investigated by the method of solving the problems on maintenance and estimating the period of annual inspections. In order to shorten the period of the annual inspection, the structural concept of fuel assemblies and the control rods was analyzed with considering the prevention of the rising of the fuel assemblies and the control rods, and the fuel exchange and maintainability. The period of annual inspections was estimated as about 39 days by using volumetric inspection technique to high temperature steam generator tubes. To make the annual inspection to the reactor module and the turbine simultaneously or with 8 overlapping days, the availability factor can be achieved to be more than 90%.
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Shigeru SAITO, Toshinobu SASA, Makoto UMENO, Yuuji KURATA, Kenji KIKUC ...
Article type: Article
Pages
267-268
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The accelerator driven system (ADS) is proposed to transmute minor actinides (MA) in high level waste from nuclear power generation, Liquid Pb-Bi alloy is a candidate material for spallation target and coolant of ADS. Pb-Bi cleaning technology is required to reduce radiation exposure during maintenance service and to decontaminate replaced components. In this study, two cleaning methods, silicon oil at 180℃ and mixture of acetic acid, hydrogen peroxide and ethanol (1 : 1 : 1) cleaning, were tested. Specimens were prepared by immersion in melted Pb-Bi. After silicon oil tests, almost of Pb-Bi remained on the surface of the specimens. It was found that some blushing were needed to remove Pb-Bi effectively. On the other hands, Pb-Bi was easily dissolved in the mixed acid and almost perfectly removed. From the results of corrosion tests, the mixed acid did not effect on base metals.
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Masatoshi FUTAKAWA, Yuji KURATA, Takashi GOTO, Shigeru SAITO, Kenji KI ...
Article type: Article
Pages
269-270
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The formation of the oxide layer is one of the key factors for the corrosion resistance of structural materials against the Pb-Bi melt. The formation of the protective oxide layer is dependent on the oxygen content in the Pb-Bi melt. The R&Ds are carried out to establish the on-line measuring and controlling system of the oxygen content in the Pb-Bi melt. A tube-type oxygen sensor has been developed using the solid electrolyte of yttria stabilized zirconia, YSZ(8-mole% Y_2O_3). The basic characteristics have been investigated under the gas/gas and the gas/Pb-Bi melt environments; i.e. the reference gas is the He gas with 10% oxygen and the oxygen content of the measured gas is varied from 0.05% to 0.1%, and the air used as reference gas/Pb-Bi with saturated oxygen solution. The temperature ranges from 350 to 600℃. The potentiometer for high impedance, KEITHLEY617,is employed. The dependency of the measured voltage on temperature was validated under the stable condition with sufficient holding time. The measured voltage under the stable condition was describable by the theoretical formulation in the gas/gas throughout the temperature range and in the air/Pb-Bi at the temperature higher than 450℃. The material and structure of electrode will be optimized to improve the dynamic response and the integrity of the sensor.
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Yuji KURATA, Masatoshi FUTAKAWA, Shigeru SAITO
Article type: Article
Pages
271-272
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Estimation of corrosion properties and development of corrosion resistant materials in liquid Pb-Bi are important issues to develop an accelerator driven system for transmutation of long-lived radioactive wastes. A series of static corrosion tests in liquid Pb-Bi were planned to study effects of temperature, oxygen concentration, various alloying elements in steels and surface treatment on corrosion behavior. Results of static corrosion tests of various alloys in oxygen-saturated liquid Pb-Bi are described. Materials of tested specimens were F82H, Mod.9Cr-1Mo steel, JPCA(14Cr-16Ni-1Mo steel), 410ss, 430ss, 2.25Cr-1Mo steel, pure Fe and pure Mo. Corrosion test were carried out at 450 and 550℃ for 3000h. It is found that oxide film forms during corrosion at 450℃. Outer corrosion film consists of Fe_3O_4 and inner corrosion film consists of Cr-Fe spinel oxide. On the other hand, FeAl film forms at 550℃ with increasing Cr content in steels. This is attributed to Al dissolved in liquid Pb-Bi from Al surface-treated steels tested in the same retort. Corrosion depth in oxygen-saturated liquid Pb-Bi decreases with increasing Cr content in steels.
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Kenji KIKUCHI, Yuji KURATA, Shigeru SAITO, Masatoshi FUTAKAWA, Toshino ...
Article type: Article
Pages
273-274
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Corrosion-erosion properties of type 316 austenitic stainless steel were investigated at 458℃. The study aims at developing ADS, accelerator driven system, for nuclear transmutation of long lived activated nuclei to shorter ones. After 3000 hrs flow of eutectic 45Pb-55Bi loop tubes were cut and analyzed by optical microscope, SEM, EDX, WDX and TEM. It is concluded that corrosion-erosion depth is maximally 0.1mm per 3000 hrs and Cr-Fe crystals were precipitated in the lower temperature of flowing channel. Further more inspection results of Electro Magnetic Pump, Electro Magnetic Flow meter and controlling value were also reported. Output signal from EMF was stable after certain time duration. In this experiment oxygen content in Pb-Bi was not actively controlled but Pb-Bi was covered by 4N Argon gas.
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Minoru TAKAHASHI, Yingxia QI, Susumu YOSHIDA
Article type: Article
Pages
275-276
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Related to Pb-Bi cooled nuclear reactors, the interaction between the steels and the liquid Pb-Bi metals was investigated experimentally, and simulated by the molecular dynamics method to investigate the mechanism of the steel corrosion. Pb and Bi atoms penetrated into the steels and simultaneously the steels dissolved into the liquid Pb-Bi metals to form an adhered layer.
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Kuniaki MIURA, Tatsuya ONIZAWA, Minoru TAKAHASHI
Article type: Article
Pages
277-278
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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A lead-bismuth alloy is promising as a coolant of the FBR and a spallation target material. An electromagnetic flow meter is used as a composition apparatus of that lead-bismuth testing device. As for the lead-bismuth, corrosion to the structure metal is a problem. Though stainless steel is the corrosion resistance metal, It was known that it corrode in the lead-bismuth of 500℃. Therefore, it is desirable to use it in less than 500℃. But, when temperature of lead-bismuth is less than 400℃, wettability of the lead-bismuth to the stainless steel get poor. The wettability of the electrode becomes unstable, too. Therefore, output of the EMF changes every time. The problem of the unstable wettability has already been solved by the Rh plating electrode. But, the Rh plating electrode, which improved wettability, has the possibility to make it produce the corrosion of the electrode. Therefore, we must evaluate rate of the corrosion about the Rh plating electrode. We soaked a Rh plating electrode into the melting lead-bismuth of 400℃, and rotated an electrode at a speed of 1m/s, and investigated the degree of the corrosion after the examination. As a result, after seventy-hour examination, 5μm corrosion was seen. After this, a long test will be done.
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Toru OBARA, Terumitsu MIURA, Yoshiyuki FUJITA, Hiroshi SEKIMOTO
Article type: Article
Pages
279-280
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Polonium issue is an important problem when Lead-Bismuth Eutectic (LBE) is used in fast reactors or in accelerator driven sub-critical systems. Some experiments were performed to remove contamination of polonium from neutron irradiated LBE. Baking in vacuum condition was performed for contaminated quartz glass plates. When baking temperature was equal or above 400℃, most of polonium was removed with other materials on the glass. When baking temperature was 300℃, only polonium was removed without removing other materials on the glass. No effect was observed when baking temperature was 200℃. This means there is a possibility that if the baking is performed for polonium contaminated materials at 300℃, only polonium can be removed without removing other non-radioactive materials.
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Nobuyuki TAKENAKA, Kou NIIDA
Article type: Article
Pages
281-282
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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A liquid lead-bismuth target circulated by a bubble pump was proposed for the accelerator target for spallation neutron source and accelerator driven system (ADS). A bubbler is required for the lead-bismuth target loop to control the oxygen concentration for avoiding corrosion. An idea was to use the bubbler as the bubble pump to make target cooling system with out mechanical pump. Measurements of the liquid velocity and the void fraction distributions in the bubble pump system in the target should be clarified at first for the thermal hydraulic designs of this target system. Neutron radiography was applied to these measurements and reasonable results were obtained.
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Yoshihisa NISHI, Izumi KINOSHITA, Satoshi NISHIMURA
Article type: Article
Pages
283-284
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Recently, the utilization of the lift pump is examined in a small reactor of the lead-bismuth eutectic cooling. Then, the experiments concerning about void behavior and performance of the lift pump in three kinds of risers (1124mm in height and inside diameters φ69.3mm, φ106.3mm, φ155.2mm) were performed by using lead bismuth eutectic. The main results are as follows : (1) The local void fraction varies in horizontal plane in case of the big diameter riser. (2) The lead-bismuth circulating flow rate evaluated by a present design method becomes lower than that of experiments in case of medium and small diameter risers. This design method can be used as an outline evaluating function for these cases, considering the evaluation accuracy of the pressure loss of the test section in the calculation. (3) In the big diameter riser, the present design method may excessively evaluate the lead-bismuth circulating flow rate. It though that the circulation head will not occur in the experiments such as a results of the present design method because the void rises biasing in horizontal plane in case of big diameter riser though the present method is one dimensional model.
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Kazuyuki Okuno, Keishu Ikeda, Naoki Uda, Tomoyuki Hirayama, Hiroo Kond ...
Article type: Article
Pages
285-286
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Secondary sodium loop elimination is proposed for the loop type LMFBR with using Advanced Intermediate Heat Exchanger (AIHX) for reduction in size and cost. This heat exchanger contains primary sodium tubes, ant tertiary water tubes in a tank filled with intermediate media. Pb-Bi eutectic alloy is one of a promising candidate of an intermediate medium. The result of Pb-Bi experiment in natural and near forced convection is reported.
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Yoshiyuki INAGAKI, Tetsuaki TAKEDA, Tetsuo NISHIHARA, Koji HAYASHI, Yo ...
Article type: Article
Pages
287-288
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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JAERI has been developing a hydrogen production system coupled with HTTR to demonstrate effectiveness of high-temperature nuclear heat utilization. Prior to construction of HTTR hydrogen production system, an out-of-pile test facility was fabricated to investigate transient behavior of the hydrogen production system and establish system controllability. The test facility is an approximately 1/30-scale model of the HTTR hydrogen production system and simulates key components downstream from an intermediate heat exchanger. An electric heater is used as heat source instead of a reactor. In the performance test of the test facility carried out from October, 2001 to February, 2002,the hydrogen production of 120m^3_N/h with hot helium gas was successfully achieved. This report describes the out-of test program and results of the performance test.
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Nozomu FUJIMOTO, Shigeaki NAKAGAWA, Yukio TACHIBANA, Toshio NAKAZAWA
Article type: Article
Pages
289-290
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In the High Temperature Engineering Test Reactor, which is the first high temperature gas-cooled reactor in Japan, the rise-to-power test to achieve the rated thermal power of 30MW started on October 23 in 2001 with operating the primary pressurized water cooler to remove the heat generated in the reactor core (single loaded operation mode). After the calibration of neutron instrumentation system at the reactor power of 93%, the rated thermal power of 30MW was achieved on December 7 in 2001 and the high temperature primary coolant of about 850℃ was obtained outside the reactor pressure vessel for the first time in the world. On February 27 in 2002 the high temperature secondary coolant of about 750℃, which is important for nuclear heat utilization in the future, was obtained with operating the intermediate heat exchanger as well as the primary and secondary pressurized water coolers (parallel loaded operation mode).
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Shoji KATANISHI, Kazuhiko KUNITOMI, Shoji TAKADA, Takakazu TAKIZUKA
Article type: Article
Pages
291-292
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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JAERI has undertaken the design study of gas turbine high temperature reactor, the GTHTR300. The study aimed at development of a greatly simplified design that leads to substantially reduce technical and cost requirements for earlier deployment. The GTHTR300 is expected to be an economically competitive reactor in 2010s due to newly proposed design features such as reactor core with two-year refueling interval, conventional steel material usage for a reactor pressure vessel, innovative plant flow scheme and horizontally installed gas turbine unit. This paper describes the original design features focusing on designs of reactor core and fuel, safety, power conversion system, and component technology developments. It is presented by a preliminary cost evaluation that the capital cost is less than a target cost of 200 thousands Yen/kWe. The present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
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Article type: Appendix
Pages
App2-
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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