Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Kimura, Nobuyuki; ; ; ; Kamide, Hideki; Tokuhiro, Akira; Hishida, Koichi
JNC TN9400 2000-057, 60 Pages, 2000/05
JNC-TN9400-2000-057.pdf:2.11MB
ln experimental study for the thermohydraulics of fast reactor, a simple experiment with fine measurement has been desired for understanding of phenomena and for verification of computer code rather than mockup experiments of large scale. For such purposes quality of experimental data must be improved. ln the velocity measurement, instantaneous velocity profile will have great advances for the understanding of phenomena and for the verification of computer code. ln this report two methods of the velocity profile measurement are discussed; one is ultrasound Doppler velocimetry (UDV) and the other is particle image velocimetry (PIV). These methods were applied to water experiments. The UDV was applied to pipe flow, planer jet, and the inter-wrapper flow which is seen in the gap region between subassemblies of fast reactor core. Cross check with laser Doppler velocimetly showed proper measurement of the UDV. Problems including the application to sodium experiments are also discussed. The PIV was also applied to the inter-wrapper flow. For the application to complex flow geometry, noise reduction method was developed to improve the measurement accuracy.
; Yamaguchi, Akira
JNC TN9400 2000-056, 150 Pages, 2000/05
JNC-TN9400-2000-056.pdf:6.67MB
[Purpose] The work was performed to make clear thermal-hydraulic issues resulting in the use of various coolants for fast reactors. [Method] Plant design features due to a use of working fluid other than sodium and design concepts relating a simplification of safety related systems were investigated. And based on the results, quantitative evaluation was made on the topical themal-hydraulic issues. Then both thermal stratification and striping phenomena were evaluated by the used of thermo-hydraulics computer programs. [Results] (1)Thermal-hydraulic issues Topical thermal-hydraulic issues of gaseous and heavy metal cooled reactors were extracted. (a)Gas cooled reactors : natural circulation,flow-induced vibration, depressurization accident (b)Heavy metal cooled reactors : thermal stratification, flow-induced vibration, sloshing And also the thermal-hydraulic issues relating compact reactor assembly and RVACS were extracted resulting from a simplification of safety related systems. (2)Evaluation of thermal stratification and striping phenomena. The following order of affects for the phenomena was obtained: (a) Thermal stratification: CO
Sodium Lead, (b) Thermal Striping: CO Lead Sodium
PNC TN9410 98-013, 48 Pages, 1998/03
Thermal striping phenomena characterized by stationary random temperature fluctuation are observed in the region immediately above the core exit of liquid-metal-cooled fast breeder reactors (LMFBRs) due to the interactions of cold sodium flowing out of a control rod (C/R) assembly and hot sodium flowing out of adjacent fuel assemblies (F/As). Therefore the in-vessel components located in the core outlet region, such as upper core structure (UCS), flow guide tube, C/R upper guide tube, etc., must be protected against the stationary random thermal process which might induce high-cycle fatigue. In this study, frequency characteristics of stationary random temperature fluctuations were investigated by the use of the time-series data from parallel impinging jet experiments, TIFFSS-I. From the investigations, the following results have been obtained; [Auto-Power Spectral Density Functions] (1)Higher frequency componets were decreased drastically with the close to the test piece surface, due to the presence of filtering effect by the laminar sub-layer and heat tansfer to the surface from coolant. (2)Dependence to the nozzle velocities was observed at the outside and inside positions of the laminar sub-layer region. It was due to the increasing of turbulent intensities with increase of the nozzle velocities. [Coherence Functions] (1)Coherency between outer temperatures of the laminar sub-layer was very small. 0ne of the main reasons is that the outer temperatures of the laminar sub-1ayer were dominated by the stationary random phenomena of turbulence flows. (2)It was confirmed that the coherency between immediate positions of different thermocouples had relatively higher values. [Transfer Functions] (1)The dominant frequency band of the gain was about 3 - 10 Hz for the transfer functions of the outer position to the inner position of the laminar sub-layer, and of the inner position of the laminar sub-layer to the test piece surface. (2)There wasno dependence of ...
PNC TN9410 98-007, 93 Pages, 1998/02
This report presents numeical results on thermal striping charactelistics at a tee junction of LMFBR coolant pipe, carried out using a direct numerical simulation code DINUS-3. In the numerical investigations, it was considered a tee junction system consisted of a main pipe (1.33 cm
) with a 90
elbow and a branch pipe having same inner diameter to the main pipe, and five velocity ratio conditions between both the pipes, i,e., (V
/ V
) = 0.25; 0.5; 1.0; 2.0 and 4.0. From the numerical investigations, the following characteristics were obtained: (1)Temperature fluctuations in the downstream region of the tee junction were formulated by lower frequency components (< 7.0Hz) due to the iteractions between main pipe flows and jet flows from the branch pipe, and higher frequency components (> 10.0 Hz) generated by the vortex released frequency from the outer edge of the branch pipe jet flows. (2)On the top plane of the main pipe, peak values of the temperature fluctuation amplitude was decreased with increasing flow velocity in the main pipe, and its position was shifted to downstream direction of the main pipe by the increase of the main pipe flow velocity. (3)On the bottom plane of the main pipe, contrary to (2), peak values of the temperature fluctuation amplitude was increased with increasing flow velocity in the main pipe.
PNC TN9410 97-058, 61 Pages, 1997/06
A benchmark exercise on "Tee junction of Liquid Metal Fast Reactor (LMFR) secondary circuit" was proposed by France in the scope of the said Coordinated Research Program (CRP) via International Atomic Energy Agency (IAEA). The physical phenomenon chosen here deals with the mixture of two flows of different temperature. ln a LMFR, several areas of the reactor are submitted to this problem. They are often difficult to design, because of the complexity of the phenomena involved. This is one of the major problems of the LMFRs. This problem has been encountered in the Phenix reactor on the secondaly loop, where defects in a tee junction zone were detected during a campaign of inspections after an operation of 90,000 hours of the reactor. The present benchmark is based on an industrial problem and deal with thermal striping phenomena. Problems on pipes induced by thermal striping phenomena have been observed in some reactors and experimental facilities coolant circuits. This report presents numerical results on thermohydraulic characteristics of the benchmark problem, carried out using a direct numerical simulation code DINUS-3 and a boundary element code BEMSET. From the analysis with both the codes, it was confirmed that the hot sodium from the small pipe rise into the cold sodium of the main pipe with thermally instabilities. Furthermore, it was indicated that the coolant mixing region including the instabilities agrees approximately with the result by eye inspections.
PNC TN9410 96-136, 92 Pages, 1996/05
Thermal striping phenomena characterized by stationary random temperature fluctuations are observed in the region immediately above the core exit of liquid-metal-cooled fast breeder reactors (LMFBRs) due to the interactions of cold sodium flowing out of a control rod (C/R) assembly and hot sodium flowing out of adjacent fuel assemblies (F/As). Therefore the in-vessel components located in the core outlet region, such as upper core structure (UCS), flow guide tube, C/R upper guide tube, etc, must be protected against the stationary random thermal process which might induce high-cycle fatigue. In this study, thermally response characteristics of the flow guide tube made by SUS 316 stainless steels were investigated using a boundary element method code BEMSET under the temperature transient conditions of Sine wave, quasi-random wave, and Sine wave with quasi-random components. From the numerical investigations, it was concluded that the detailed handling on turbulence phenomena in coolant is very important in the evaluation of actual LMFBRs, because of the thermally response of the structures are influenced significantly on random fluctuating components.
Otaka, Masahiko; Ohshima, Hiroyuki
PNC TN9410 96-118, 26 Pages, 1996/04
We have started to develop a whole core thermmal-hydraulic analysis code ACT(Analysis program of whole Core Thermal-hydraulics) for the purpose of evaluating detailed in-core thermal-hydraulic phenomena under various operation conditions, e,9., the normal operation and the transition from forced to natural circulation, of fast reactors. For the high accurate predictivity of the in-core thermal-hydraulics, key phenomena such as inter-wrapper flow (convection through the gaps between fuel subassemblies) and core-plenum thermal-hydraulic interaction should be accounted for. Therefore, ACT consists of four kinds of programs, i.e., intra-subassembly, inter-subassembly, upper plenum and primary loop (including intermediate heat exchanger) analysis programs, which will be made based on several thermal-hydraulic codes that have been developed at PNC and taken the verification and validation. The latter two programs are inevitable parts to give the proper boundary conditions of the in-core thermal-hydraulic analysis, especially in the natural circulation decay heat removal operation mode. These four programs will be coupled with each other and be calculated simultaneously by using parallel computers. In this report, the code development strategy and inter-wrapper flow analysis program which we developed as the first stage of the code development are presented. This program analyzes sodium single phase flow phenomena in inter-subassembly gap at whole core. The finite differential method is applied and the governing equations for fluid continuity, energy and momentum are solved simultaneously. The basic function of program was confirmed through the interwrapper flow analysis of a core consist of 37 fuel subassemblies. This program will be coupled with inter-subassembly analysis program at next stage.
*;
PNC TN9410 96-102, 40 Pages, 1996/04
In designing the shield plug of LMFBR, it is important to evaluate the thermal response between the cover gas thermal-hydraulics and the temperature fields of the shield plug at the same time. Based on the experiments which were performed by OEC, the natural convection and the thermal radiation in the cover gas layer were calculated with the structure simulating the shield plug in a detail two-dimensional model. The calculations were carried out for 8 kinds of experimental RUNs using a FLUSH code. The main results were as follows: (1)For these 8 kinds of experimental RUNs, the velocity and the temperature distributions in the cover gas layer were presented. The radial and axial temperature distributions in the rotating plug were also presented, which were difficult to measure by the experiments. (2)The boundary surface temperature between the cover gas layer and the rotating plug had the same tendencies and the calculated average temperatures on the boundary surface had good agreements with the experimental data. The average relative deviations from experimental values were less than 1.3%. (3)The natural convection of the cover gas enhanced the temperature distributions in the structure. The effects of thermal radiation on the heat transfer was relatively small and it can be neglected when the temperature of the heated aluminum disk is less than 400C.
Oka, Yoshiaki*; Koshizuka, Seiichi*; Okano, Yasushi*
PNC TY9602 96-001, 133 Pages, 1996/03
no abstracts in English
Tsukimori, Kazuyuki;
PNC TN9460 95-004, 211 Pages, 1995/12
This report describes the explanation on the new options and extensions of "FINAS" (FInite Element Nonlinear Structural Analysis System) updated version 13.0 (developed from April 1993 to July 1995). The items are as follows. (1)3 kinds of spring-supported base elements (2)4-node quadrilateral plane strain element (3)Off-set function utilized with 3-dimensional beam element (4)Definition of centrifugal force by angular velocity and pivot (5)2-node heat flow element for thermal hydraulic analysis (6)Addition of CQC method and ABS method as mode superposition method for spectrum response analysis (7)Addition of logarithmic interpolation as spectrum data interpolation method for spectrum response analysis (8)*Multi-point input function of spectrum data in spectrum response analysis (9)Output function of maximum reaction force in spectrum response analysis (10)Output function of member forces for shell element and bar element (11)Plotting function of normal stresses and shear stresses in the vectorial plot charts (12)Plotting function of user-defined state variables in the analysis by an arbitrary constitutive equation (13)**Scaling function in X-Y plane plotting function (14)Improvement of calculation efficiency in surface contact analysis (15)Addition of Sloan's argorithmin in renumber function (16)Calculation function of all eigenvalues in the analysis of structure system (17)Extension of the limit of maximum degrees of freedom (up to 4,000,000) (18)**Provision of user's subroutine for the arbitrary constitutive equation (19)**Provision of user's subroutine for the arbitrary element (20)Extension of two-surface cyclic plasticity model by introducing temperature dependency (21)Revision of execusion commands and monitering function of statistical information in UNIX environment (22)Automatic verification system in UNIX environment (23)Guide of utility programs supporting the development of FINAS (EWS version) The properties of new functions were verified ...
PNC TN9410 94-182, 29 Pages, 1994/06
A three-dimensional temperature fluctuation analysis was carried out using a general-purpose multi-dimensional thermohydraulics direct numerical simulation code DINUS-3 for parallel impinging jet experiments in sodium and water simulating thermal striping phenomena. The code utilized a third-order upwind scheme and an adaptive control system based on the Fuzzy theory to control time step sizes. The calculated results in both the cases showed evident differences mainly attributed to fluid properties such as heat conductivity, molecular viscosity, etc.. From the analysis, the following conclusions were obtained. (1)The amount of the temperature fluctuation damping by fluid mixing in sodium flow shows approximately two times larger than in water flow. While the damping amounts due to the laminar sub-layer in sodium flow is approximately 1/3 of that in water flow, (2)The variance of the probabilily density function for the calculated sodium temperature fluctuations is two times of the calculated water temperature fluctuations, and (3)The histogram of the normalized amplitude for calculated water temperature fluctuations can be fitted by a Layleigh distribution. By contrast, in the sodium case, the profile is very much like a exponential distribution. The results obtained in this work are very encouraging; the DINUS-3 code is one of the efficient measures to evaluate thermal striping phenomena in sodium, a low Prandtl number fluid, when one wishes to perform thermal striping evaluation in Liquid Metal Fast Breeder Reactors.
PNC TN9410 94-111, 42 Pages, 1994/04
Thermal striping phenomena are characterized by stationaly random temperature fluctuations and observed in the region immediately above the core exit of LMFBRs due to the interactions of cold and hot sodium. To evaluate the phenomena, it is neccessary to consider a time-dependent heat transfer coefficient to structures from fluid, in the same manner as a evaluation of a stationaly temperature fluctuation in fluid. For this purpose, a computer program THEMIS (Time-dependent Heat transfer Evaluation by Monte Carlo Direct Simulation) has been developed for the thermohydraulic analysis based on the Boltzmann equation. A two-dimensional duct flow problem has been solved to check the fundamental performance of the THEMIS code. The main results are as follows: (1)Axial distribution of molecular velocity U has shown good agreement with the solution of the Navier-Stokes equation under the condition of Kn=0.0002. (2)An acceleration on the VP-2600 vector processor is about 12 times as the VP-2600 scalar processor. Future works of the THEMIS code development are (1)investigation of the applicabilities in a non-isothermal fluid system and in a complex geometry system and (2)verification with detailed experimental results.
; *; ; ; ; Matsumoto, Mitsuo
PNC TN8410 92-187, 21 Pages, 1992/05
Computer code for fuel temperature evaluation of LMFBR at early burnup has been developed. On fule temperature evaluation, especially at early burnup, the fuel restructuring model and the gap conductance medel are important. These models which are installed in the temperature evaluation code, were verified based on the results of irradiation tests using the foreign fast reactor and "JOYO". This paper describes the essential parts of the models and the functions of the code (DIRAD) which is used for the fuel temperature evaluation at early burnup of LMFBR such as the prototype fast breeder reactor "MONJU".
PNC TN9410 92-105, 65 Pages, 1992/04
A thermal striping phenomenon characterized by a random temperature fluctuation occurs in the region immediately above the FBR core due to the temperature difference of the core outlet coolant between subassemblies. In this study, a direct numerical simulation code DINUS-3(Direct NUmerical Simulation using 3rd order upwind scheme) has been developed based on the third order upwind scheme and investigated applicability of the DINUS-3 code to temperature fluctuation analysis. From the analysis of von Karman vortex streak behind a rectangular obstacle, the following results have been obtained: (1)Change of the vortex frequency (the strouhal number St) with increase of the Reynolds number Re can be estimated by the DINUS-3 code. (2)A stationary random turbulence fluctuation including a buffer region between the transition and the turbulent regions can be predicted using the DINUS-3 code. And the followings became clear after the analysis of a nonisothermal parallel jet experiment using water. (1)A temperature fluctuation phenomenon including complicated frequency components can be simulated well using the DINUS-3 code. (2)Calculated dominant frequency has shown good agreement with the experiment. From the analysis, it is concluded that the DINUS-3 code based on the third order upwind sheme has a sufficiently high potential in providing good interpretation of experimental results related to the temperature fluctuation phenomena such as thermal striping.
; Haga, Kazuo
PNC TN9410 92-050, 71 Pages, 1992/02
Objective : A conceptual design of a fast reactor system was studied for deep sea research submersibles diving to the maximum depthes of 10,924m and 8,000m. Method : A space reactor concept was used for the system. Primary coolant of the system was NaK, whose temperatures was set as 680 and 550 C at the exit of a reactor vessel. Secondary system was a closed brayton xcycle using He(60)-Xe(40) gas as working fluid. Electric power output was 20kWe. Thermal efficiency, transported thermal energy, and flow rates and temperatures of the gas and NaK were calculated at closed Brayton cycle analyses. Results : The conceptual design was drawn, based on the size of an each component fixed with the calculated results of these values. The system could be set in a pressure hull comprising of a 2.3m
shere and a 1.1m pipe. A simple figure was drawn of the research submersible loading the system. The whole length of the submersible was about 14m. Its weights were about 100ton and 70ton for the maximum depthes of 10,924m and 8,000m respectively. It could be carried by a nother ship. Conclusion : The submersible had the following features compared with the one loading electric cells on account of affluent electric power generation by the fast reactor system. A continuous stay longer than a week and movement at a high speed were made possible over a deep sea bottom. An illuminated region was very wide during sea bottom survey. Observation by watching was possible over a wide region. Therefore the submersible could be considered to be used for detail observation over crackes in the Japan trench and etc.