[in Japanese]

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Hokkaido Electric Power Company, Inc. (HEPCO) supplies electricity to almost all area of Hokkaido. Its service area accounts for about one-fifth of Japan's area, on the other hand, the population of the service area only accounts for 4.4% of the nation. This means Hokkaido's nature is precious, and one of HEPCO's missions is to protect such environment, with providing stable electricity. Therefore, nuclear power, which does not emit greenhouse effect gas for generation, is becoming more important. HEPCO's operating nuclear power stations are Tomari No.1 unit and No.2 unit. Their generation capacity is 579MW respectively. Now, No.3 unit is under construction. Its generation capacity is 912 MW and it will be operational in December 2009. In Hokkaido, about one fourth of electricity is now produced by nuclear power, however, after Tomari No.3 is completed, about 40% of electricity will be produced by nuclear. So, Tomari No.3 unit will contribute stable supply of electricity in the first half of 21st century and prevent global warming in Hokkaido. This paper describes the present status of Tomari No.3 unit construction with major specifications and our efforts to prevent global warming.

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Turbine blades are protected against surface degradation by the use of overlay MCrAlY (M=Ni and/or Co) coatings or Al diffusion coatings of β-NiAl, β-Ni(Pt)Al, and γ-(Ni,Pt)_3Al. The degradation of coatings is due to spallation of Al_2O_3 scales and precipitation of topologically close-packed (TCP) phases. Furthermore, the Ni-aluminide coated alloys can suffer significant degradation of mechanical properties under creep conditions. Novel coatings as EQ coating, Pt-modified γ'-Ni_3Al coating, and diffusion barrier coating system were critically reviewed, and establishment of compatibility of anti-oxidation and mechanical properties were discussed. Diffusion-barrier coating systems with an inner Re-based alloy layer and an outer Ni-aluminide layer were introduced in detail and anti-oxidation properties and creep behavior of the coated alloys were investigated It was found that Re-based alloys such as σ(Re(W), Cr,Ni) are very promising candidates as a diffusion barrier between alloy substrates and Ni-aluminides, resulting in improvement of both the anti-oxidation property and creep-rupture life.

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CRIEPI has developed the fiber-optic sensor that can be applied up to 600℃ and measurement system. However, reliability of conventional heat-resistant sensor was poor due to brittleness of fiber and structural design. In this report, improvement of heat-resistant sensor was successfully carried out and the sensor could be applied up to 650℃. Minimum detectable size of microcrack using the fiber-optic sensors was evaluated based on FEM simulation of elastic wave propagation. It was estimated that microcracks radius of above 2mm could be detected using the heat-resistant sensor on an actual steam piping.

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In ultrasonic testing of complex shaped parts such as turbine blade roots, it might be difficult to distinguish echoes from defects and component corner parts. Simulation software for ultrasonic testing plays an important role in avoiding false calls when there is a lack of mock-ups and reference induced defects. CRIEPI has developed high speed simulation software to predict B scope images for defects, based on the geometrical theory of diffraction (GTD) to calculate ultrasonic waves transmitted from an angle probe. Analytical equations have been newly derived to express echoes received by the probe. This paper deals with applicability of the CRIEPI's software to prediction of B scope images constructed from the test data of complex shaped part.

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In the nuclear power plant, where many small-bore piping connected to vibrational sources like pumps, it is important to evaluate vibrational stress efficiently to keep the plant operating safely. The purpose of this study is to develop a method to measure vibrational stress efficiently by using multiple contactless displacement sensors. The applicability of the method is verified by vibration tests with a pipe. In the vibration tests, the stress calculated by the proposed method was compared with the stress measured by strain gauges. As the results, the calculated stress was in good agreement with the measured stress though having some errors which are negligible comparing to endurance limit of failure. Therefore the method we developed is applicable to measure vibrational stress of small-bore piping.

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The oscillation of pipes containing two-phase flow is very important not only for the design of heat exchangers but also for the estimation of flow behavior by detecting the vibration or noise transferred from sounding rod with pressing components. The skilled engineers sometimes can estimate the two-phase behavior with vibration or noise from components such as heat exchangers or steam generators. To understand the oscillation behavior and possibility to estimate the flow behavior, the air-water two-phase flow experiments were conducted with small vertical tubes of 2 and 11.5mm in inner diameter. The oscillation of differential pressure was (DP) measured at the long observation span more than fifty times diameter to avoid the static pressure oscillation due the fluctuation of void fraction. The acceleration oscillation (WV) was also measured at several location of pipes. The root mean square (RMS) value of WV and DP was well correlated with Lockhart-Martinelli parameter. It was also demonstrated that the two-phase quality could be estimated with the proposed correlation for RMS values when the liquid flow rate and RMS value were known.

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Effects of Cr content and environmental factors, pH and dissolved oxygen concentration, on removal rate of carbon steels due to flow accelerated corrosion have been examined by experiments. pH dependency of the FAC rate has been found to be directly related to solubility of magnetite. Cr content holds a strong impact on the FAC rate regardless of pH values from 6.84 to 10.4. Addition of 1% Cr to a carbon steel reduces the FAC rate by one order of magnitude under the environmental conditions, where magnetite forms. Addition of oxygen up to 1200ppb changes the oxide from magnetite to hematite, resulting in significant improvement in corrosion resistance.

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This paper describes experiment and numerical simulations for macro and micro flows behind an orifice model in a square pipe, which are carried from the viewpoint of flow accelerated corrosion (FAC). The measurements of velocity field behind the orifice model were carried out using particle image velocimetry, and the variations of velocity field with respect to the accuracy of the orifice position were studied. It is found that the reattachment behavior of the flow is highly influenced by the orifice position, which is a critical problem for predicting the pipe thinning phenomena by FAC. The DNS simulation was also conducted for calculating the macro flow behind the orifice. The result suggests that the DNS simulation is applicable to the prediction of pipe thinning macro flow for highly aged nuclear plant. The micro flow simulation can predict the pipe thinning phenomena near the wall.

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In this study, in order to evaluate the effects of flow field on corrosion rate due to flow accelerated corrosion (FAC), an orifice flow was measured and calculated. The diameter of pipe is 50 mm and that of the orifice is 24.3 mm, and flow velocity in a water loop was set at 2.41 m/s. Flow field was measured by laser Doppler velocimetry (LDV) and particle image velocimetry (PIV), and compared with a calculation for the same flow conditions. Measurements of wall shear stress downstream of the orifice was also planed. The calculated velocity distributions of standard k- agreed qualitatively with PIV data and quantitatively with LDV data. Instantaneous flow field measured by PIV showed vortices around the jet from the orifice and some of them reached near the pipe wall.

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In this study, in order to evaluate the effects of flow field on corrosion rate due to flow accelerated corrosion (FAC), a corrosion rate downstream of an orifice was measured using the electric resistance method. The diameter of the pipe is 50 mm and that of the orifice is 24.3 mm, and flow velocity of the experimental loop was set at 5m/s, and the temperature of water was controlled within ±1 at 150deg-C. There were no significiant circumferential difference in measured corrosion rate,and the maximum corrosion rate was ovserved at 1D or 2D downstream from the orifice. The ratios of the measured corrosion rate and the caluculated wall shear stress at the 1D downstream from the orifice to the value at upstream under well developed flow agreed well.

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Flow Accelerated Corrosion (FAC) requires considerable attention in plant piping management, for its potential of catastrophic pipe rupture of main piping systems. In view of fluid dynamics, the most essential factor to be considered is mass transfer at the inner surface of the pipe. Mass transfer coefficients are determined by fluid properties and piping geometry, however, no universal correlation exists, which is adaptable to various types of piping elements with strong turbulence. In this study, the modeling of mass transfer coefficient was progressed based on Chilton-Colburn analogy and utilizing "Effective Friction velocity" from the hydraulics in the viscous sub-layer along the wall. FAC experiments with PWR condensate water condition and CFD for the flow were conducted with a contracted rectangular duct. By considering the turbulent velocity of the viscous layer into the mass transfer coefficient, the correlation with the FAC thinning rate improved, effectively.

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August 2004, a pipe rupture accident occurred at The Kansai Electric Power Company Mihama Unit3. Japan Society of Mechanical Engineers (JSME) recognized that it was an urgent problem to settle the rules on Pipe Wall Thinning Management by Fluid Flow. JSME enacted "rules on Pipe Wall Thinning" that stipulates the basic requirements of pipe wall thinning management, considering from these situations. In 2006, JSME enacted the "rules on Pipe Wall Thinning Management for PWR Power Plants" (JSME S NG1-2006, JSME rules for PWR) that satisfies the requirements of "rules on Pipe Wall Thinning". This JSME rules for PWR stipulates the process of inspection plan, measurement, evaluation and maintenance. This paper focuses on the technical grounds that specify the management systems, pipe components and initial FAC rate.

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Strongly motivated by every stakeholder not to repeat Mihama pipe rupture accident in August 2004. JSME Main Committee on Codes & Standards on Power Generation Facilities immediately launched a special task force to develop Rules on Pipe Wall Thinning Management for BWR, PWR and Fossile Power Plants respectively. The authors describes the process of the development of Rules for BWR Power Plants from the view point of collections and analysis of fields data of pipe wall thinning.

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The first edition of the JSME rules on pipe wall thinning management for thermal power generation facilities (JSME S TB1-2006) was issued in March 2006, and its latest edition was issued in September 2007, which describes the technical requirements to meet the JSME performance-based rules for pipe wall thinning management (JSME S CA-1 2005). The latest JSME rules describe the specific requirements for the inspection of piping system that are susceptible to the wall thinning damage based on the analyses of 24,774 inspection data obtained at the thermal power plant in Japan. This paper presents outline of the latest JSME rules including basic philosophy and technical requirements on the inspection and testing practices.

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The pipe-wall thinning can be one of the most important problems in safety as well as maintenance. After the Mihama accident, JSME established a performance-based rule and technical rules for thermal power plants, PWRs, and BWRs for the management. Various organizations began the research regarding the pipe-wall thinning. Pipe-wall thinning is complex phenomena which relate to the fluid dynamics, the water chemistry, and material sciences. The management can be an integrated technology that consists of screening of management locations, the evaluation of thinning rate, the method of the wall thickness measurement, the evaluation of remaining period for fit for service, and the repair method, etc. In JSME, a R&D strategy was considered based on the needs to revise and enhance the rules. This report shows the outline of the strategy.

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Pipe wall thinning caused by liquid impingement erosion is one of the serious problems occurred in piping systems of electric power plants. Liquid impingement erosion is thought to have the threshold velocity that erosion does not occur or erosion rate is vanishingly small. It was reported that a threshold velocity is 100m/s for a pure iron and 110m/s for a carbon steel by Shimogaya, and 70m/s for stainless steel by Mittsubishi Heavy Industries, Ltd. In general, it is highly unlikely that, however, a stainless steel with high work-hardening is eroded faster than a carbon steel. Therefore, liquid impingement erosion tests were carried out for a S15C carbon steel and a SUS304 stainless steel to clarify the flow velocity dependence and the threshold velocity of liquid impingement erosion. It was found that threshold velocity is 80m/s for a S15C and 120m/s for a SUS304. Also, we clarified the erosion mechanism due to liquid impingement by scanning electron microscopy.

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Liquid droplet impingement erosion (LDI) is defined as an erosion phenomenon caused by high-speed droplet attack in a steam flow. In a power plant, pipe wall thinning by LDI is observed steam piping system. Because LDI usually occur very locally and is difficult to detect, a prediction of LDI location is required for the safety of the plant system. Therefore, as ultimate objectives, we set the development of the prediction tool of LDI location that can use in power plants easily (LDI Prediction Code). In previous researches, we achieved to enable the evaluation of all the local flow conditions that affect LDI materially. Therefore, in this study, we tried to suggest the evaluation method for LDI position with organizing the results and knowledge systematically. As a result, we suggested the evaluation method of LDI location in steam piping with 3 steps. And we also suggested the function of LDI sensitivity with incorporating the velocity, wetness and droplet behavior, and tested this system to the steam piping model. We found that the consideration of the droplet behavior change the rank of LDI sensitivity at each elbo in the piping.

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With regard to High Pressure(HP) feed water heater of thermal power plant at Tokyo Electric Power Company(TEPCO) sites, inspection of Feed Water(FW) tubes wall thickness are conducted whenever required such that frequent tube leak occurs.As a standard inspection methodology, FW heater is disassembled during planned outage, tube wall thickness is measured by UT, then install plugs at the both end of FW tube if its measured wall thickness is found below calculated threshold.However, the root causes of wall thinning of FW tube are various such as erosion and corrosion, based on wall thinning condition, the above threshold is not applied but utilizing the other technically well-grounded evaluation method is sometimes more rational.Therefore, TEPCO classified wall-thinning condition based on inspection data and established technically well-grounded and rational evaluation methodologies of FW tube wall thickness to suite each wall thinning condition.Moreover, with recent improvement of inspection technique, technology enabled faster, larger amount, and more accurate data acquisition, TEPCO has developed the systematized evaluation methodology that can transact data acquisition and evaluation simultaneously.This article introduces the logic of evaluation methods and examined algorithms to make them systematized.

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Recently, in the power plant piping, the wall-thinning problem by high temperature water and a two-phase flow (high temperature water and steam) attracts attention. Since the wall-thinning mechanism was not clarified, it is the purpose which understanding the mechanism of wall-thinning in plant, installed the piping corrosion test facility in which a long-term continuous test is possible, and started the wall-thinning examination of carbon steel piping. In addition, the ultrasonic sensor for high temperature, which can be measured in the state of the high temperature, was installed, and monitored wall thickness change during an examination period. For about two months, as a result of performing monitoring, the measured piping thickness was falling uniformly and checked that this monitoring system had caught the tendency of wall thinning. The difference of a monitoring result and the thickness measurement result after an examination was small. It identified that this monitoring system could accuracy monitoring also in high temperature.

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The remote field eddy current testing (RFECT) is usually used for inspection of ferromagnetic small tubes with inner coils. The aim of this study is to clarify the precise characteristics of RFECT for inspection of flat plates with pancake coils, which has rarely appeared in the literature. The study was performed by actual experiments and computations based on electromagnetic analysis to evaluate the capability of RFECT to detect a defect and estimate the shape of a defect. This paper introduces some of the results obtained from these experiments and computations for a simple probe configuration having only one excitation and one pick-up coils. The results shows even this simple configuration enables RFECT to detect local wall thinning and roughly estimate its shape.

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S. Backhaus and G. W. Swift [Nature 399, 335 (1999)] proposed the new type thermoacoustic engine based on traveling wave energy conversions. They demonstrated the engine can achieve an efficiency of 0.30. We numerically investigated the stability limit of the new type thermoacoustic engine which proposed by Backhaus and Swift. Also, we showed the dependence of the stability limit on the shape of the tube composing the new type thermoacoustic engine.

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It is necessary to develop a new power generation system using the waste thermal energy around 100 degrees C from the steam turbine which thrown away into the sea or the river. The theoretical formula which predicts the rotation speed w and the output power P of the SMA engine, was drawn from the size of a SMA belt, Young's modulus, and the radiuses of high-temperature and low-temperature wheels. We verified the part of validity of this theory by experiment.

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The purpose of the research is to enhance the average cooling capacity during a cycle by a new cycle time allocation. In the study, the performance of the single stage adsorption refrigeration cycle with the new cycle time allocation was predicted by simulation. The specific cooling capacity (SCC) and the coefficient of performance (COP) were compared with those of the cycle with conventional cycle time allocation. The optimization of the cycle time was performed using the particle swarm optimization. The optimum cycle time of the new cycle time allocation at each hot water temperature was obtained and it was compared with the optimum performance by the conventional cycle time allocation. The results showed that the new cycle time allocation would improve the SCC of the single stage adsorption cycle due to the prolonged adsorption time.

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In the present paper, adsorption isotherms of R507A on highly porous activated carbon (Maxsorb III specimen) has been measured at a temperature range of 0 to 65℃ and pressures varying from 0.1 to 1.3 MPa. The experimental results are fitted to Dubinin-Astakhov (DA), Langmuir and Toth isotherm equations and found to be fairly consistent within the experimental errors. Using the isotherm equations Henry's law coefficients has been evaluated.

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The study investigated the effect of the improved partial load COP of adsorption chillers on the cogeneration system in an office building. The partial load COP of the adsorption chiller was maximized by optimizing the cycle time. The COP of the adsorption chiller was increased with smaller partial load ratios by the extended cycle time. The performance of the cogeneration system with an adsorption chiller was analyzed by simulation, and the energy saving ratio of the system was presented. The energy saving ratio was compared with that by the cogeneration system with an absorption chiller. The results showed that the adsorption chiller was advantageous given that the adsorption chiller had the same rated COP value as the absorption chiller.

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When a freight ship is in a harbor, a Diesel engine generator is operated to supply electric energy in the ship. Exhaust gas from the Diesel engine causes air pollution in the harbor area. In order to solve the air pollution, we have tried to develop a heat recovery system with Stirling engine generators. In this paper, we report a composition of the heat recovery system and a control system for the Stirling engine, experimental results of the Stirling engine generators with exhaust gas from a Diesel engine in our laboratory, and operating results of field tests on a ship.

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Recently, Stirling engine has been get attention again as the technology that reduced the effects on the environment because of the feature that the external-combustion engine can use various heat. If a high efficiency Stirling engine power generating system using the exhaust heat from factory or engine can be constructed by using the feature of Stirling engine, the exhaust heat recovery by the electric power which is a high added value becomes possible. In this study, the power generation performance of tens of kW class Stirling engine in the exhaust heat use was evaluated, and the characteristic was able to be understood. Moreover, from that result the optimized power generating system that assumed application to an actual factory was studied, and then the additional combustion system and two series configuration system of STE confirmed high efficiency power generation was possible by the calculation. In addition, a basic design was executed and the problem was clarified.

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Wastes are defined as a new energy and desired to utilize an energy source beneficially. The authors pay attention to better utilization of wastes, which is a method to convert wastes into energy, and present a waste incineration and power generation system built up of an incinerator and a Stirling engine generator. The system has a maximum incineration capacity of 49kg/h and power generation of 10kW. The incinerator is cooled by circulating water in order to enable a long life and supply heat by a hot water or air flow. The Stirling engine is constructed as a four cylinder double-acting type and has a built-in generator. The Stirling engine generator is installed in a secondary combustion space. An auxiliary kerosene burner enables the Stirling engine to generate electricity continuously. The waste incineration and power generation system is suitable for works, housebreakers, farms and so on, because of waste management and energy cost reduction. Also it is effective in environmental preservation and saving energy.

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In the envisioned high-power density core plant, the degradation of stability is concerned that is attributed to the shortening of rod heat conduction time constant upon the dense fuel grid and the increment of pressure drop caused by the wall friction. Under power and flow oscillated condition, the two-phase flow behavior might be different from that under the steady condition. Therefore, the thermal-hydraulic test using the rod bundle under the oscillation condition was performed to obtain the verification data for the analytical code. In this paper, the test results were described. It was found that the critical power decreased under flow oscillating condition, and the power oscillation had a little effect on the critical power.

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In the envisioned high-power density core plant, the degradation of stability is concerned that is attributed to the shortening of rod heat conduction time constant upon the dense fuel grid and the increment of pressure drop caused by the wall friction. To confirm the influence of such degradation on the fuel soundness, the bundle geometry critical power test was held under flow-power oscillation condition which envisages the unstable phenomenon occurring under in the flow transient event. This paper describes the analysis results of the cited test with sub-channel code NASCA, and the discussion of the mechanism of boiling transition under flow-power oscillating condition.

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Characteristics of a steam injector and steam condensation phenomena on water jet surface in the steam injector were experimentally examined. In visual experiments of behavior of the water jet in the steam injector, many large waves were observed on the water jet surface. The waves showed the tendency to grow as those proceeded downstream. Direct steam condensation on to the water jet surface in the steam injector was mainly controlled by radial heat transport in the water jet. The radial heat transport in the water jet was considerably more effective than that in the usual turbulent heat transport in a pipe. It was pointed out that this highly effective radial heat transport mechanism was created by local circulation in the water jet that was produced by waves on the water jet surface. Waves on the jet surface ware examined. Based on it, the heat transfer correlation of the jet flow accompanying the direct condensation of steam on the surface was proposed.

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A Steam Injector (SI) is a simple, compact and passive pump. We are developing this innovative concept by applying the SI system for core injection system in emergency core cooling systems (ECCS) to further improve the safety of nuclear power plants. Passive ECCS in nuclear power plants would be inherently very safe and would prevent severe accidents by keeping the core covered with water (Severe accident-free concept). The passive core injection system (PCIS) driven by high-efficiency SI is a system that, in an accident such as a LOCA (loss of coolant accident), attains a higher discharge pressure than the supply steam pressure used to inject water into the reactor by operating the SI using water stored in the pool as the water supply source and steam contained in the reactor as the source of pressurization energy. This report describes the experiments and the analytical simulation on a SI-driven PCIS for innovative-simplified nuclear power plant. In addition, we conducted the analytical simulations of SI, which grew in size for the actual nuclear power plant.

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We have studied nuclear power plant for district heating. Already some towns and villages in Hokkaido have requested small reactor for district heating. Using existing technology allows us to shorten development period and to keep a lid on development cost. We decided to develop new reactor based on "MUTSU" reactor technology. "MUTSU" had already proved its safety. And "MUTSU" reactor was boron free reactor. It allows plant system to become more compact and simple. And load following capability by core reactivity become bigger. It means to reduce control rod movement It leads to dependability enhancement. We calculated burn-up calculation of erbium addition fuel. In the result the core life became about 10 years. In the district heating system, there are not only district heating but also snow melting with warm water. It uses steam condenser's heat, which are only discharged now. This small plant has passive safety system. It is natural cooling of containment vessel. In case of loss of coolant accident, decay heat can remove by natural convection air cooling after 6 hours. Decay heat within 6 hours can remove by evaporative heat transfer of pool on containment vessel.

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The recent worldwide "Nuclear Renaissance" is encouraging the globalization of our nuclear business and making us aware of the increasing importance of the human education and trainings for it. The basic concept of MHI's human resource development and its improvement is "The improvement in the skills and motivation of each employee leads to the strengthening of the company-wide technology base." Under this concept we are improving our job efficiency continuously by means of information technology, institutionalizing the means to improve the individual skills and motivation and investing for the effective succession of the skills. In order to take real advantage of those efforts for maintaining, strengthening and effectively handing down the nuclear technology base, it is imperative to keep the volume of actual jobs. So, we have to keep in mind that having actual business continuously is extremely important to keep the sound and solid technology base.

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Due to environmental concerns such as global warming, needs for nuclear power is increasing. However, many expert engineers and technicians are now entering a period of retirement. And due to weak demands of new plant construction for long years, opportunity for technology learning/experience had been lost. Therefore, to secure human resource and to develop their ability are urgent issues for nuclear industries. Hitachi nuclear division continues efforts for technology transfer and human resource training. This paper describes the following two activities. (1) Improvement of common technical basis, and implementation of PDCA cycle (2) Development of supporting tools to accelerate technology transfer through OJT (On the Job Training)

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Recently, from the viewpoint of the reduction of carbon-dioxide emissions that cause global warming and the energy security, the importance of nuclear power generation is recognized again as an effective approach for solving the problems, and many nuclear power plants are planed to be constructed worldwide. On the other hand, the experienced engineers will face the time of the retirement in the near future and technology succession and human resource development has become important problems. In this paper, Toshiba's Nuclear Energy Systems & Services Division's activity concerning technology succession and human resource development will be introduced.

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