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This paper investigates the valuation of a replacement project of nuclear power plants under the deregulated electricity market. The replacement project consists of two components: the decision to decommission an existing plant and the decision to construct a new plant. In the replacement project, the decommissioning decision should be made considering not only the profitability of the existing plant but also the profitability and costs of the construction of the new plant. Real options theory is used to determine the optimal timing of the decommissioning and construction. In order to examine the effect of decommissioning time and decision making one, we consider a time-lag for these decision making times. We show the dependence of the replacement project value on uncertainty and time-lag.

Replacement of nuclear power plants has the possibility of affecting the management of electric power suppliers. Therefore, in the nuclear policy, a depreciation method as an equalization method, which means that part of the investment cost is accumulated as an allowance, and after the start of operation, the depreciation cost in the replacement project is equalized, has been introduced in Japan. In this paper, we evaluate the replacement of nuclear power plants by taking into account the uncertainty of operating costs and the depreciation cost in order to examine the effect of the depreciation method on the decision criteria of the replacement. We found that the equalization method is effective for inducing the acceleration of the replacement. Furthermore, we show the relationship between the uncertainty and the depreciation method. It turns out that as uncertainty increases, the difference in investment threshold between the equalization method and the existing depreciation method decreases, and that in option value increases.

On March 30, 2007, Japan's electric utilities reported the results of a complete review of their power-generating units to the Nuclear and Industrial Safety Agency of the Ministry of Economy, Trade, and Industry (METI). The Ethics Committee of the Atomic Energy Society of Japan (AESJ) then recommended an assessment method to analyze the seriousness of the problems from multiple perspectives in order to support the public's understanding of the reported problems. Accordingly, the Ethics Committee conducted the assessment. The assessment considered each reported problem associated with nuclear power-generating units and the preventive measures completed between June 2007 and September 2008 (corrective measures continued beyond that period). The results were presented at the autumn conferences of AESJ in 2007 and 2008, and are discussed in this report.

本研究では，文献調査と関係者へのインタビューをもとに，事前了解条項を持たない浜岡協定を通じて自治体がどう関与しているのかを明らかにし，その背景要因を考察した．結果，関係自治体は事前了解項目を敢えて盛り込まず，技術的判断を避ける形で運用を行ってきたこと，県よりも立地地域の判断が意思決定の中心にあること，隣接自治体でも立地自治体と同様のプロセスが展開されること等が明らかとなった．こうした自治体の関与を他立地と比較すると，自治体に規制権限のない現行法制と齟齬が少ない点，且つ自治体・事業者ともに過度な政治的負担を避けうる点が，特長といえる．こうした関与が可能となっている一因として，浜岡協定が早い段階から隣接自治体も巻き込んだ形で締結され，幅広いステークホルダーの関与を実現してきたことが挙げられる．

In Japan, safety of nuclear facilities is regulated by the central government and local governments are responsible for protecting the local public. To operate nuclear facilities in local communities, local governments would conclude safety agreements with power companies. In recent years, local governments have used the safety agreements as excuse for delaying the operations of nuclear facilities. The legal basis of the safety agreements was questioned by some who considered that this was the cause of the stranded relationship between local governments and power companies, and in some cases, the interrupted nature of electricity supply. To understand the sources of this difficult relationship, safety agreements must be analyzed, although these documents may have undergone revisions, and various regulations may have changed. By analyzing the safety agreements and revisions, we found that the relationship between local governments and power companies gradually changed over time, which can be divided into the following 3 stages: (1) in the early 70s, the dawn stage when local governments groped with the situation of nuclear facilities built in their communities; (2) from late 70s to 90s, the stage when local governments demanded information, and (3) from late 90s to present, the stage when local governments demand information and trustworthiness. This paper shows the results of analyzing the relationship changes between local governments and power companies. We conclude that viewpoints of local governments on nuclear power evolve, as social responsibilities of power companies stipulated in safety agreements also evolve over time.

The confidentiality system concerning the physical protection of nuclear materials and nuclear facilities was enacted by revision of the Nuclear Reactor Regulation Law in 2005. We made a comparative analysis with the information security in governmental agencies or financial sectors, in order to consider the way the sensitive information management concerning the physical protection of nuclear materials and nuclear facilities should be. The considerations in this paper are as follows. (1) In order to secure a suitable level of security, close cooperation should be achieved among related governmental agencies. (2) A cycle that continuously evaluates whether suitable management is performed should be established. (3) Excessive secretiveness should be eliminated. (4) An information-sharing system among the related persons beyond the frame of governmental agencies and electricity companies should be established. (5) Improvement in the social acceptability of the sensitive information management is important. (6) Although it is important to perform evaluation by the consideration of suitable balance with information disclosure, it is also important that it is positively shown to society.

The present paper analyzes the entry strategies into the electricity market of two firms that have power plants under price uncertainty and competition. We consider the symmetric and asymmetric two firms, which have either a thermal power plant or a nuclear power plant. The differences between the thermal power plant and the nuclear power plant, such as the cost structure and operational flexibility are modeled. The threshold values of market entry are calculated for each firm with either the thermal power plant or the nuclear power plant as the leader or the follower. We show the dependence of cost structures on entry thresholds of the leader and the follower into the electricity market. For various market and cost conditions, the diagrams of the leader are also shown.

In a branch pipe with one closed end, the cavity flow penetrates into the branch pipe from the main loop and a thermal boundary layer occurs because the cavity flow is a hot fluid, but heat removal causes a colder fluid in the branch pipe. This thermal stratification may affect the structural integrity. Therefore, a pipe design standard to suppress thermal fatigue should be established. The pipe design standard consists of the maximum penetration depth Lsv and the minimum penetration depth Lsh. In order to establish an evaluation method for Lsh, a visualization test and a temperature fluctuation test were carried out. A theoretical formula for thermal stratification was introduced from the heat balance model. Then the model was used to obtain an empirical equation from the map of fluid temperature fluctuation. This method can predict the vortex penetration depth by cavity flow in horizontal branch pipes. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(1):38–55, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20135

This paper describes a new high-speed micro PIV technique for measuring both red blood cell velocity and plasma velocity to investigate rheology of blood flow in microcirculation. The measurement system consists of an epi-fluorescent microscope equipped with a high-speed camera with an image intensifier and two sets of colour filters. The technique was applied to in vitro blood flow through a micro round tube of 100 µm diameter. Velocity distributions of dyed red blood cells and plasma seeded with fluorescent particles were obtained separately. The obtained velocity distributions have a high spatial resolution of 9.0 µm × 2.2 µm and high temporal resolution of 6000 Hz.

This paper described about flow visualization of a gas-liquid two-phase flow in vertical channel with contraction. We have found that the pulsation for void fraction and pressure are occurred by the contraction. However, the mechanism of pulsation is not cleared. Therefore, we construct Dynamic PIV/IST (Infrared Shadow Technique) system using high-speed camera and laser systems to visualize a two-phase flow. We use the system and analyze the profiles of bubble segments and flow structure of liquid phase around bubble segments.

近年，1k×1k画素で，2kHzの撮影速度を持った高速度カメラや高繰り返しレーザーが開発され，高速流れの瞬時の流動構造を逐次抽出することが可能となった．このようなシステムをダイナミック PIV システム(Dynamic PIV system)と呼んでいる．本研究では，２台の高速度カメラを利用し，サイズの異なる複数の画像を取得するマルチスケールPIVシステムを提案し，時間および空間におけるダイナミックレンジを同時に拡大する方法について述べている．また，異なる画像サイズを得るためのカメラとレーザーの制御方法も述べている．このマルチスケールPIVを渦流れのシミュレーションによる人工画像および自由噴流の応用実験に適用し，本マルチスケールPIVの有効性およびその問題点について述べている．

In a branch pipe with closed end, the cavity flow penetrates into the branch pipe from the main loop and the thermal boundary layer occurs because the cavity flow in a hot fluid, but the heat removal causes the colder fluid in the branch pipe. It is possible for the thermal stratification to affect the structural integrity. Therefore, it is necessary to establish the pipe design standard to suppress thermal fatigue. The pipe design standard consists of the maximum penetration depth L{sub sv} and the minimum penetration depth L{sub sh}. In order to establish the evaluation method for L{sub sh}, the visualization test and the temperature fluctuation test were carried out. Theoretical formula of thermal stratification was introduced from the heat balance model. Using this model, the empirical equation was obtained from the map of fluid temperature fluctuation. The method can predict the vortex penetration depth by cavity flow in the horizontal branch pipe. (author)

A method for visualizing the spatial distribution of oxygen using particles coated with pressure-sensitive dye is presented. The proposed technique, called the PSParticle method, is a hybrid system combining the technologies of pressure-sensitive paint (PSP) and particle image velocimetry (PIV) and allows the particle velocity and oxygen distribution to be measured simultaneously. As intensity-based imaging is not applicable in this system, a luminescence lifetime-based imaging technique involving double frame imaging is introduced. The system is calibrated and demonstrated in application to measurement of the oxygen distribution in an air jet.

The interaction between chemical reactions and the flow field in microfluidic devices is investigated by a laser-induced fluorescence technique refined for use at microscopic spatial resolution. The pH distribution of chemically reacting flow at a Y-junction in a neutralization reaction in a microfluidic device is successfully visualized at a spatial resolution of 0.89 µm × 0.89 µm.

Thermal striping tests in mixing tees with same pipe diameters were conducted in order to construct databases for entablishment of an evaluation method for high-cycle thermal fatigue of piping systems. Hot and cold water with a terperature difference of 40 degrees Kelvin were supplied to the mixing tee. In order to clarify characteristics of fluid temperature fluctuations and its heat transfer, temperature fluctuations of the fluid and pipe wall were measured as the velocity ratio of the flow in the branch pipe to that in the main pipe was varied from 0.1 to 5. Characteristics of flow patterns and fluid temperature fluctuations were reported in our previous paper. In this paper, heat transfer coefficients were evaluated by using the power spectrum method. The ratios of the measured heat transfer coefficient to that evaluated by Dittus-Boelter's empirical equation were independent of the velocity ratio and Reynolds number, and they were within 1.6.

The Dynamic PIV system (Time-resolved PIV) has been applied to the high-speed mist flow with edge obstacle in a narrow channel. The boundary layer has been clearly visualized with the high-speed camera and high repetition double-pulse laser. The target area is 10mm with 10m/s, i.e. Re=10, 000. The top side and bottom side edge flow are captured to evaluate the detail flow structure of the boundary layer.

The authors successfully visualize the density variation of supercritical carbon dioxide under forced convective heat transfer using schlieren and shadowgraph techniques as research toward the precise characterization of supercritical fluid behavior. Using a new experimental setup with short-pulse infrared laser and high-speed camera and by employing frame straddling, sequential images are obtained at an interval of only 0.48 ms. A noise-reduction step is also added to the cross-correlation algorithm to produce clear and accurate velocity distribution maps. The proposed technique is demonstrated to be a highly effective and accurate analysis tool for the behavior of supercritical fluids, and is expected to be useful in research on precision applications such as nuclear reactors.

In this study time-resolved proper orthogonal decomposition (POD) is proposed for the new technique of dynamic (digital) particle image velocimetry (DPIV), and applied to study the coherent structures at the near field of a round jet flow. Time-resolved POD is computed in the radial direction, the axial direction and the temporal domain, in which the turbulence can be easily measured by DPIV. As a result, large-scale vortical structures and their spatial and temporal evolution at the round jet mixing layer are uncovered.

This paper reports a new technique for measuring oxygen density distribution in space. The PSP (Pressure Sensitive Paint) are usually used for noncontact measuring pressure distribution on a surface. The pressure measurement is based on the phenomena of luminescence quenching by oxygen molecules. In order to measure the oxygen density distribution in space, instead of a surface pressure distribution, the PSParticle (Pressure Sensitive Particle) for seeding gas was developed. Due to the particles are always moving in space, the Double Frame Imaging (DFI) be developed. This new method can give the relationship between oxygen concentration and image intensity. The method that uses PSParticle can be obtained the velocity information as the PIV technique at same time. Therefore, this new technique has a possibility to compose the PIV-PSP hybrid system.

This paper presents a visualization of a 3D gas density distribution, which arose from a safety analysis of a high-temperature gas cooler reactor. The density distribution is reconstructed from holographic interferograms using the techniques of computed tomography. In the reconstruction process, a new reduced bandlimit technique is used in the filtered-backprojection algorithm to deal with the truncated projection data with noise. The results reconstructed from 12 view directions are verified qualitatively by an oxygen molarity detector. It shows that the filtered-backprojection algorithm, integrated with the reduced bandlimit technique, can reconstruct the 3D density distribution from the truncated and noisy projections, and that holographic interferometry is a non-disturbing and powerful tool in flow-visualization for 3D gas flows.

Marangoni convection, driven by an interfacial instability due to a surface tension gradient, has become a significant problem in the crystal growth on the ground or in a microgravity environment. To suppress and control the convection is important for material processing. Especially in the crystal growth by liquid encapsulated czochralski or liquid encapsulated floating zone technique, in which the melt is encapsulated with an immiscible medium, Marangoni convection can occur on the liquid–liquid interface and on the gas–liquid free surface. In the present paper, experiments were carried out with a double liquid layer of silicone oil and fluorinert both in an open-boat system and in an enclosed system. Flow in a cavity subject to a horizontal temperature gradient was observed. An interactive flow near the interface was measured by using particle image velocimetry technique. The measured flow field seemed to agree sufficiently with the numerical prediction.

A self-induced free-surface oscillation termed ‘self-induced sloshing’ was observed in a rectangular tank with a submerged and horizontally injected water jet. Self-induced sloshing is excited by the flow itself without any external force. Its behaviour was examined by experiment. The dominant frequency was found to be close to the first or second eigenvalue of fluid in a tank. The conditions of sloshing excitation were obtained for four tank geometries. They were called the ‘sloshing condition’, and defined in terms of inlet velocity and water level. Sloshing conditions were found to be strongly dependent on inlet velocity and tank geometry. A two-dimensional numerical simulation code was developed to simulate self-induced sloshing. The code was based on the boundary-fitted coordinate (BFC) method with height function. The numerical results were qualitatively verified by the experimental results, and were found to correlate well in terms of flow pattern, free-surface shape and sloshing conditions. In this study, sloshing growth was evaluated quantitatively using the simulation results. Oscillation energy supplied for the sloshing motion during a sloshing period (Econ) was calculated from simulation results. Sloshing growth was found to be strongly related to the sign and magnitude of Econ. The distribution of Econ showed that jet flow had a strong correlation with the sloshing growth. It was clarified that sloshing growth was primarily dependent on the spatial phase state of jet fluctuation. A governing parameter of self-induced sloshing, the modified Strouhal number Sts, was proposed on the basis of numerical evaluations of oscillation energy. The value of Sts suggests that one or two large vortices generated by jet fluctuations exist between the inlet and outlet during a sloshing period. When Sts is approximately either 1 (first stage) or 2 (second stage), self-induced sloshing occurs consistently in all experimental cases. The dependence of sloshing on inlet velocity, water level and tank geometry was revealed using Sts. For several tank geometries, a sloshing mode shift or jet mode (stage) transition was found to occur due to changes in inlet jet velocity. The combination of sloshing mode and jet stage can determine the state of the self-induced sloshing. As a result of this study, we propose a new excitation mechanism of self-induced sloshing, represented by a simple feedback loop closed by sloshing motion and jet fluctuation. The overall physical oscillation mechanism of self-induced sloshing was clarified using this feedback loop.

A form of digital speckle tomography has been proposed for calculating transient three-dimensional density distributions. Multiple CCD images have captured movements of speckles due to the variation in density among three angles of view simultaneously and instantaneously so that asymmetrical and transient flows can be measured. Initially, the variations in density of one-nozzle and two-nozzle test sections have been investigated by the use of a cross-correlation method involving the speckle displacements. The results have been compared with measurements made by Mach-Zehnder interferometry to confirm the accuracy. Then, the speckle movements for downward flow of carbon dioxide from a circular small opening with a vertical partition (CO2-air exchange flow) have been obtained by the cross-correlation tracking method so that those distances can be transformed into deflection angles of laser rays for density gradients. The transient three-dimensional density fields have been reconstructed from the deflection angles by tomography.

Turbulence modification with polymer additives, i.e., Tom's effect, is a well known phenomenon. In this study, Tom's effect at a free surface was experimentally investigated. The turbulence at a free surface was generated by a horizontal liquid jet. A new specklegram technique was proposed in order to quantitatively measure the free-surface shapes caused by a turbulent jet. The specklegram method was very simple and was able to evaluate the free-surface waves accurately. The measurement confirmed that the surface of a polymer solution was less wavy than that of water. The jet beneath the free surface was measured by the LDV. The turbulence diffusion of the polymer jet was much smaller than that of the water jet. The surface turbulence was found to be modified by the polymer solution indirectly. The modification was a consequence of the Tom's effect at the shear layer around the jet.

A technique for simultaneous measurement of three-dimensional density and velocity distributions was evaluated. Holographic particle image velocimetry (HPIV) was used to reconstruct three-dimensional velocity distributions from three-dimensional particle images recorded on a hologram. Optical tomography (OT) was used to reconstruct three-dimensional density distributions from multidirectional two-dimensional interferogram images. When a flow field with density variation was illuminated by coherent plane waves, spherical waves were scattered by the particles (particle images), and the illuminating beam was modulated by the density variation (interferogram images). Using a reference beam, both particle and interferogram images could be recorded on a single hologram. Using the spatial filtering extraction (FX) technique, information on both images could be extracted separately from the hologram. In the experiment, a jet of helium gas introduced into air containing small particles was measured. Both particle position and fringe shift caused by the density variation could be observed, demonstrating the effectiveness of the proposed technique

Transient and asymmetric density distributions have been investigated by digital specklegram tomography. Multiple CCD images captured movements of speckles in three angles of view simultaneously because the flows were asymmetric and transient. The speckle movements between no flow and downward carbon dioxide flow from a circular small opening with a vertical partition have been calculated by a cross-correlation tracking method so that those distances can be transferred to deflection angles of laser rays for density gradients. The transient three-dimensional density fields have been reconstructed from the deflection angles by a tomography method.

The behavior of ionized carbon during the simulated plasma disruption is investigated with the Magneto-Plasma-Dynamic (MPD) Arc Jet. The temporal and spatial distributions of the ionized carbon were measured by emission spectroscopy. Distributions of CII and CIII were obtained. For the isotropic graphite target, the emission intensity increased as the target is exposed by the heat flux from plasma. Two consecutive peaks of intensity were observed at the point near the target surface. A simple model of redeposition and surface roughness could explain these phenomena.

Cover gas is constantly supplied to a main tank the bottom of which is connected to that of a subtank. The water levels in the tanks oscillate alternately until the free surface in the main tank pushed by the gas reaches the bottom end of a vertical release pipe. Then the gas is ejected from the main tank, resulting in a sudden surface rise and plugging of the pipe inlet. The cover gas pressure increases again, thus, gas ejection occurs intermittently. The behavior of the oscillation system can be expressed by a set of linear equations that are properly selected according to the water surface position. The calculated interval between the ejections exhibits chaotic features : a simple return map of the disorderly fluctuating interval and oversensitiveness to the initial condition. The effect of superimposed random noise is examined.

The single-phase natural circulation in a single loop system has been studied by many researchers. In a multiple loop system, the characteristics of natural circulation are more complicated because of the interaction between the loops. In this study, the effects of the multiple loop on the natural circulation instability were investigated experimentally. As the simple multiple loop system, the toroidal loop with insulated connecting tube between both sides (θ-loop) was evaluated. The variation of flow regime in the θ-loop was almost the same as that in the single loop. However, the chaotic condition in an inclined θ-loop was narrower than that of inclined single loop. The flow and the pressure transfer in the connecting tube played an important role in the chaotic condition in the θ-loop.

Buoyancy-driven helium-air exchange flow through double openings was experimentally investigated. The double openings with rectangular cross-section (w/2×d) were settled side by side in w direction. The exchange flow rate and the flow pattern around the openings were simultaneously measured. To clarify the effect of geometry, the cross-section of the opening was systematically varied. Under the smaller d/w geometry, the separated flow pattern (s) was observed, in which the upward and downward flows flew separately in the double openings, respectively. Under the larger d/w geometry, the unseparated flow pattern (u) was observed, in which the upward and downward flows flew inside the openings. The counter-current flows were observed in the openings. The exchange flow rate was a function of the flow pattern. For the flow pattern (s), the exchange flow rate could be predicted using the flow network model with considering the entrainment. For the flow pattern (u), the flow in the opening was same as the exchange flow through a single opening with the same geometry.

Buoyancy-driven helium-air exchange flow throgh double small openings was investigated. The double openings with rectangular cross section were settled side by side, in order to evaluate the interaction between the flows through the double openings. In the exchange flow experiment, the exchange flow rate and the flow pattern around the openings were simultaneously measured. Two flow patterns were formed even in the same boundary condition, i.e., (a)uncaptured flow pattern with larger exchange flow rate, and(b) captured flow pattern with smaller exchange flow rate. The entrainment effect caused the two flow patterns. In order to clarify the mechanism, characteristics of the entrainment were evaluated in the forced flow experiment. Only the flow pattern(b)was observed in the forced flow experiment. The relationship between the entrainment ratio α and flow rate q was measured for the flow pattern(b), resulting in the entrainment characteristic curve. A new correlation for the exchange flow rate was proposed with considering the entrainment. With applying the obtained entrainment characteristic curve to the correlation, the exchange flow rate was predicted. It agreed with the measured value better than the conventional prediction without consideration of the entrainment.

Thermal-hydraulics governs mechanical load and environmental condition of structural materials, thus a quantitative understanding of thermal-hydraulic behavior is of real importance to a correct estimate of many kinds of plant aging processes. The current status of thermal-hydraulics for prediction of plant aging is summarized and subjects for future research are discussed.