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Kawada, Koji; Matsuki, Takuo*; Miyahara, Shinya
JNC TN9400 2005-043, 48 Pages, 2005/08
Sodium spray fire tests at the initial sodium temperature of 250 deg-C were conducted under the atmospheric conditions of air and 3% oxygen containing nitrogen to determine the sodium burning rate and the aerosol release fraction and compare them with the test results at the initial sodium temperature of 500 deg-C in air atmosphere.In the tests, sodium was supplied using a commercial spray nozzle into a stainless steel vessel of 100 m volume (SOLFA-2). The sodium burning rate was calculated from two independent methods : the consumption rate of oxygen in the vessel and the enthalpy change of vessel components during the test. The aerosol release fraction was determined from the comparison between the measured aerosol concentrations and the calculated ones by the ABC-INTG code. The main conclusions were as follows, (1) In air atmosphere, (a) sodium droplets ignited instantaneously and the spray fire was observed, (b) the sodium burning rate was about 440 g-Na/s and the fraction of supplied sodium was about 70%. (2) In 3% oxygen containing nitrogen, (a) ignition of sodium droplets was not observed, and (b) the sodium burning rate was about 44 g-Na/s and the fraction of supplied sodium was less than 10%.
Hara, Akio; Tsuji, Takashi*; Nishimura, Mizue*; Hoshi, Kazuyoshi*; Yagi, Masahiko*; Kawada, Koji*; Hou, J.-Y.*
JAERI-Conf 2005-007, p.270 - 275, 2005/08
Borehole log interpretation methods, which are usually used by petroleum exploration companies, are applied for evaluating heterogeneity of deep underground diatomaceous mudstones in the Horonobe area. Natural ray log and electrical micro image (EMI) log data were used for the log interpretation. Five sedimentary facies, A to E, were established from the EMI log interpretation. Significant correlations between the sedimentary facies, the chemical contents, the natural ray level, and the electric conductivity in the diatomaceous mudstone were seen. Spatial distribution of the diatomaceous mudstone, in lithology and thickness, was recognized through borehole correlation, which seems to reflect the sedimentary environment change.
Kawada, Koji
Saikuru Kiko Giho, (27), p.80 - 83, 2005/06
We carried out reflection seismic and multi-offset VSP surveys at JNC Shobasama-site to develop the investigation technique in the granite area, and evaluated the applicability of these geophysical methods. As the result of this study, we consider that a) It is possible to infer the existence of the lower angle fracture zone in the granite by reflection seismic survey and b) Multi-offset VSP supplements the result of reflection seismic survey and it is possible to infer the distribution of the fracture zone in deeper area in the granite.
Hara, Akio; Tsuji, Takashi*; Hoshi, Kazuyoshi*; Yagi, Masahiko*; Nishimura, Mizue*; Kawada, Koji*; Hou, J.-Y.*
Program and Abstracts, p.65, P. 65, 2005/02
To evaluate heterogeneity of diatomaceous mudstone in Horonobe area, physical properties and lithofacies of sedimentary rocks have been estimated from natural ray log data and electrical micro imaging (EMI) log data. Spatial distribution of heterogeneity of sedimentary rocks has been discussed by comparison of log data acquired from several boreholes. Five sedimentary facies, A to E, have been established. Sedimentary facies A and B, which can decipher bedding planes clearly in EMI image, have been developed horizontally with low ray and high SiOcontents while sedimentary facies D, bedding planes are not clear to decipher, have been developed horizontally with high ray and low SiOcontents. The results of this study support the estimation of Hara (2004) namely the strata which characterized with high ray have been high AlOcontents and rich in terrigenous sediments such as clay minerals, on the other hand, the strata characterized with low ray have high SiOcontents and rich in diatomaceous fossils. Layered sedimentary facies can correlate between boreholes based on natural ray log and EMI log analysis. Sedimentary system and spatial distribution of strata of Horonobe area can estimate from the results of the facies correlation.
Hoshi, Kazuyoshi*; Hou, J.-Y.*; Kawada, Koji*; Tsuji, Takashi*; Suwabe, Mizue*
JNC TJ8400 2005-009, 67 Pages, 2005/01
Developing a method to evaluate heterogeneity of sedimentary rocks is very important for a site survey and a property test of the site. We studied siliceous shale from wells in the Horonobe area, and developed a sedimentary process modeling software in order to establish a method to evaluate heterogeneity of sedimentary rocks. Well log analysis of Koetoi and Wakkanai Formations revealed variations of porosity, shale content, and amount of erosion. We correlate marker beds, and establish a compaction curve for siliceous shale in the Horonobe area. EMI analysis revealed alternation of thin beds which can not been recognized by naked eyes. Chemical analysis shows that this heterogeneity originates from a variation in diatom and clastic material contents in the rock. We also examined seismic data using GDI method. For sedimentary modeling software, we expanded the sedimentary simulation module, and attached another module to compare the calculated results with actual data. We also attached the module to find the best input parameters. We performed a test run using the geology model we made for Horonobe area.
Hoshi, Kazuyoshi*; Hou, J.-Y.*; Kawada, Koji*; Tsuji, Takashi*; Suwabe, Mizue*
JNC TJ8400 2005-008, 138 Pages, 2005/01
Developing a method to evaluate heterogeneity of sedimentary rocks is very important for a site survey and a property test of the site. We studied siliceous shale from wells in the Horonobe area, and developed a sedimentary process modeling software in order to establish a method to evaluate heterogeneity of sedimentary rocks. Well log analysis of Koetoi and Wakkanai Formations revealed variations of porosity, shale content, and amount of erosion. We correlate marker beds, and establish a compaction curve for siliceous shale in the Horonobe area. EMI analysis revealed alternation of thin beds which can not been recognized by naked eyes. Chemical analysis shows that this heterogeneity originates from a variation in diatom and clastic material contents in the rock. We also examined seismic data using GDI method. For sedimentary modeling software, we expanded the sedimentary simulation module, and attached another module to compare the calculated results with actual data. We also attached the module to find the best input parameters. We performed a test run using the geology model we made for Horonobe area.
Kawada, Koji
Saikuru Kiko Giho, (26), 114-120,136 Pages, 2005/00
Focusing on the cover layer materials (as the Radon Barrier Materials), which could have the effect to restrain the radon from scattering into the air and the effect of the radiation shielding, we produced the radon barrier materials with crude bentonite on an experimental basis, using the rotary type comprehensive unit for grinding and mixing, through which we carried out the evaluation of the characteristics thereof.
Kato, Arata*; Kawada, Koji*; Masui, Yasuhiro*; Tsuji, Takashi*; Suwabe, Mizue*
JNC TJ8400 2003-094, 71 Pages, 2004/02
It is very important to estimate the facies distribution of heterogeneous sedimentary rocks for geological disposal of high level radioactive waste. The heterogeneousness of sedimentary rocks is due to variable distribution of grain size and mineral composition. The objective of this study is to establish the evaluation method for heterogeneous sedimentary rocks based on forward model. In this study, the following items were studied.1.}The sedimentary system for Koetoi and Wakkanai formations in Horonobe area was compiled based on published papers.2.}The cores of HDB-1 were observed mainly from sedimentological view.3.}The facies and compaction property of argillaceous rocks were studied based on physical logs and core analysis data of wells.4.}The structure maps, isochrone maps, isopach maps and restored geological sections were made.5.}The soft wear for sedimentary model to show sedimentary system on a basin scale was developed.
Kato, Arata*; Kawada, Koji*; Masui, Yasuhiro*; Tsuji, Takashi*; Suwabe, Mizue*
JNC TJ8400 2003-093, 178 Pages, 2004/02
It is very important to estimate the facies distribution of heterogeneous sedimentary rocks for geological disposal of high level radioactive waste. The heterogeneousness of sedimentary rocks is due to variable distribution of grain size and mineral composition. The objective of this study is to establish the evaluation method for heterogeneous sedimentary rocks based on forward model. In this study, the following items were studied. 1..The sedimentary system for Koetoi and Wakkanai formations in Horonobe area was compiled based on published papers. 2..The cores of HDB-1 were observed mainly from sedimentological view. 3..The facies and compaction property of argillaceous rocks were studied based on physical logs and core analysis data of wells. 4..The structure maps, isochrone maps, isopach maps and restored geological sections were made. 5..The soft wear for sedimentary model to show sedimentary system on a basin scale was developed.
Kawada, Koji
Saikuru Kiko Giho, (23), 115- Pages, 2004/00
Focusing on the cover layer materials (as the Radon Barrier Materials), which could have the effect to restrain the radon from scattering into the air and the effect of the radiation shielding, we produced the radon barrier materials with crude bentonite on an experimental basis, using the rotary type comprehensive unit for grinding and mixing, through which we carried out the evaluation of the characteristics thereof.
Jitsu, Koji; Ono, Isao*; Kawada, Koji; Kurihara, Akikazu; Yatabe, Toshio
JNC TN9400 2003-062, 84 Pages, 2003/06
It is one of the important matters to select the design base leak (DBL) of the steam generator (SG) of a fast breeder reactor (FBR) in sodium-water reaction. The selection of the DBL has an influence on safety, economical efficiency, etc. of the plant.It is necessary to develop the computational model to estimate the sodium-water reaction phenomenon with high accuracy and rationality for selecting the DBL of large SGs. The blow down evaluation on overheating tube failure phenomenon is pointed out as part of the necessary improvements, since the behavior of overheating tube failure is largely affected by the steam conditions inside of the tube.This document shows the validation of blow down model for the LEAP code, which is developed as analysis code for failure propagation of the SG tubes, by test's data in Sodium-Water Reaction Test Rig No.1 (SWAT-1R). The following results have been obtained through the validation.(1) Within the mass flow rate ranging from 160 to 540 g/s in SWAT-1R, it has been confirmed that calculated internal pressure shows good agreement with the test's one. The pressure in tests becomes close to the calculation by Ogasawara model in critical flow models.(2) Mass flow rate is appropriately calculated of the test after about 10 seconds in the beginning of test. Calculated mass flow rate by Ogasawara model is closer to the test than that by Moody model.(3) On both Moody model and Ogasawara model in critical flow models, internal pressure in calculation shows the underestimation of HT-3 test. It will be necessary to investigate this reason.(4) Mass flow rate at the pipe near water heater tank shows the large overshoot in the beginning of test. Also, the small overshoot that supposed to be moved from upper stream appears at the nozzle about 2 seconds. Since these overshoots are estimated too large, these phenomena should require to be examined.(5) As calculated mass flow rate at the nozzle in both critical models have a tendency to be evaluated l
Kawada, Koji; ; Ohno, Shuji; ; Miyake, Osamu; Tanabe, Hiromi
JNC TN9400 2000-089, 258 Pages, 2000/08
As a part of the work for investigating the sodium leak accident which occurred in the Monju reactor (hereinafter referred to as Monju) on December 8, 1995, threetests, (1)a sodium leaktest, (2)a sodium leak and fire test-I, and(3)a sodium leak and fire test-II, were carried out at OEC/PNC, The main objectives of these tests were to confirm the leak and burning behavior of sodium from the damaged thermometer, and the effects of the sodium fire on the integrity of the surrounding structure. This report describes the results of the sodium fire test-I carried out as a preliminary test. The test was performed usjng the SOLFA-2 (Sodium Leak, Fire and Aerosol) facility on April 8, 1996. In this test, sodium heated to 480C was leaked for approximately l.5 hours from a leak simulating apparatus and caused to drop onto a ventilation duct and a grating with the same dimensions and layout as those in Monju. The main conclusions obtained from the test are shown below: (1)Observation from video cameras in the test revealed that jn the early stages of the sodium leak, sodium dripped out of the flexible tube of the thermometer. This dripping and burning expanded in range as the sodium splashed on the duct. (2)No damage to the duct itself was detected. However, the aluminum louver frame of the ventilation duct's lower inlet was damaged. lts machine screws came off, leaving half of the grill (on the grating side) detached. (3)NO large hole, like the one seen at Monju, was found when the grating was removed from the testing system for inspection, although the area centered on the point were the sodium dripped was damaged in a way indicating the first stages of grating failure. The 5mm square lattice was corroded through in some parts, and numerous blades (originally 3.2 mm thick) had become sharpened like the blade of a knife. (4)The burning pan underside thermocouple near the leak point measured 700C in within approximately 10 minutes, and for the next ...
Tobita, Yoshiharu; Morita, Koji; Kawada, Kenichi; Niwa, Hajime; Nonaka, Nobuyuki
PNC TN9410 97-079, 106 Pages, 1997/09
The sequences of ULOF (unprotected loss-of-flow) event in the prototype FBR has been evaluated, as a part of the research and development (R&D) in the reactor safety research, reflecting the latest experimental and analytical knowledge on CDA (core disruptive accident) which has been accumulated at O-arai Engineering Center. In the R&D activity on the FBR reactor safety subject, we have accumulated the experimental knowledge of mitigation mechanism in the energy generating process in CDA, utilizing international in-pile safety experimental programs such as CABRI program, as well as the out-of-pile experiments in Japan and foreign countries. This knowledge has been reflected to the development and validation of the SAS and SIMMER code. The objectives of this study are to apply these new assessment techniques to the prototype FBR and to clarify quantitatively in detail the energy generation process of CDA. In this study, an emphasis is placed on the event sequence of the melt progression phase ("transition phase") which has been recognized as one of the important issues of CDA analysis. The major parameters to be considered in this phase are the change of the mobile molten fuel mass and the history of the fuel motion, and also the relation between these parameters and energy generation mechanism. The following methods and approaches have been taken into account in this evaluation study. (a)The SAS4A code is used for the analysis of the transient behavior in the first Phase driven by core voiding ("initiating phase"), and the SIMMER-III code is used for the latter phases with melt-progression (tansition phase) and also the energy conversion process from the thermal one to the mechanical one. These codes have been developed and validated under the collaboration among PNC, CEA and FZK. (b)The uncertainty band of the void reactivity worth and Doppler coeficient has been reduced through the re-evaluation of the critical experimental data in the neutron physics area. ...
Kawada, Koji; Ohno, Shuji; Miyake, Osamu; ; ; Tanabe, Hiromi
PNC TN9410 97-036, 243 Pages, 1997/01
As a part of the work for investigating the sodium leak accident which occurred in Monju on December 8, 1995, three tests, (1)sodium leak test, (2)sodium leak and fire test-I, and (3)sodium leak and fire test-II, were carried out at OEC/PNC. Main objectives of these tests are to confirm leak and burning behavior of sodium from the damaged thermometer, and effects of the sodium fire on integrity of the surrounding structure, etc. This report describes the result of the sodium fire test-I carried out as a preliminary test. The test was performed using SOLFA-2 (Sodium Leak, Fire and Aerosol) facility on April 8, 1996. In this test, sodium heated to 480C was leaked for approximately 1.5 hours from a leak simulated apparatus and caused to drop onto a ventilation duct and a grating with the same dimensions and layout as those in Monju. The main conclusions obtained from the test are shown as below. (1)Observation from video cameras in the test revealed that in early stages of sodium leak, sodium dropped down out of the flexible tube of thermometer in drips. This dripping and burning were expanded in range as sodium splashed on the duct. (2)No damage to the duct itself was detected. However, the aluminum louver frame of the ventilation duct's lower inlet was damaged: Its machine screws had come off, leaving half of the grill (on the grating side) detached. (3)No large hole, like one seen at Monju, were found when the grating was removed from the testing system for inspection, although the area centered on the point that the sodium attacked was damaged in a way indicating the first stages of grating failure: The 5-mm- square lattice was corroded through in some parts, and many blades (originally 3.2 mm thick) had become like the blade of a sharp knife. (4)The burning pan underside thermocouple near the leak point measured 700C in roughly 10 minutes, and for the next hour remained stable between 740C and 770C. There was a ...
Himeno, Yoshiaki; Morikawa, Satoshi; Kawada, Koji; Yorita, E.*; Fujiwara, T.*; Kaneshige, T.*; Irie, S.*
PNC TN9410 91-092, 11 Pages, 1991/01
To develop a ceramic liner, a selection test of materials, an improvement test of selected material, and a feasibility test of the liner have been conducted.in the selection test, fifty commercially available high temperature cement and ceramics were subjected to thermal shock test (tst), sodium exposure test(set), and sodium flame exposure test (sfet). From test results, alumina/silicon-carbide (AlO-sic)mixture base castable refractory was selected in consideration of material cost, and material availability for a simpler liner construction in the buildings. The selected material was subjected to the improvement test. from the test, proper weight fractions of additives such as alumina cement and silica were determined. Drying conditions were also determined. Finally, a sodium burning pan made of concrete whose inner surfaces were covered with the improved AlO-sic base castable refractory was fabricated and was used for a sodium burning test.
Kawada, Koji*; ; *; Himeno, Yoshiaki
PNC TN9410 88-164, 28 Pages, 1988/12
[Purpose]A sodium pool fire test has been conducted in low oxygen containing nitrogen atmosphere to determine the sodium burning rate and aerosol release rate and compare them with calculated results by the SOFIRE-MII code. [Method]After installing a burning pan in a 3m test vessel, FRAT-1, the test vessel was filled with nitrogen gas includlng 3% in volume of oxygen gas. Then, the test was started by supplying a sodium (175400C) in the burning pan. The sodium burning rate was determined from the consumption rate of oxygen in the test vessel. The aerosol release rate was determined from total aerosol mass recovered. [Result](1)The sodium burning rate depends on the sodium pool temperature. As the result of a comparison of the experimental sodium burning rate values with the calculated ones by the SOFIRE-MII code, it was cleared that the former was lower than the latter in case of sodium pool temperature below 400 C and its differance was more than one order of magnitud at 175C. This reason is based on the fact that the burning rate is controlled by the masstransfer of oxygen at high pool temperature, while it is controlled by the reaction between oxygen and sodium at low pool temperature. In final, an empirical formula that agree with the experimental results was derived. (2)The aerosol release rate also depends on the sodium pool temperature. It is less than about 10% of the sodium burning rate. Assuming that the aerosol release rate is propotional to the sodium burning rate, an empirical formula which dependends on sodium pool temperature giving the maximum value at each sodium pool temperature was decided.
Kawada, Koji*; ; Hiroi, Hiroshi*; Himeno, Yoshiaki
PNC TN9410 88-004, 44 Pages, 1988/01
Since sodium leak and fire researches have been performed at high-temperatures simulating an accident during the rated reactor operation knowledge of sodium leak and fire at low-temperatures which may happen at Ex-vessel Storage Tank or during the partial power operation of the reactor was very li,ited. Therefore, the present test was carried out to clarify the ignition temperatures and the temperature at which aerosol starts to release during sodium spray, column, and pool fires. Sodium spray and column tests were conducted at Sodiu Fire Test Rig (SOFT-1), while sodium pool test was carried out at Sodium Leak Fire and Aerosol Test Rig (SOLFA-1). The following test results were obtained from these tests. (1)Sodium Spray Test. The ignition temperature was 160C depending upon the droplet diameter of sprayed sodium. (2)Sodium Column Test. (a)Sodium main flow did not ignite, while the scattered sodium droplets ignited. (b)The ignition temperature of the main flow rebounded on a pan was 180C. (c)The ignition temperature of deposits on a pan was 160 C. (3)Sodium Pool Test. (a)The ignition temperature of the static pool ranged from 280 to 315C. (b)Temperature at which aerosol starts to release was determined to be 140 to 160C by visual in spection. (c)After extinguished artificially by closing a lid, sodium reignited at temperatures higher than 80 C when the lid was reopend.
Himeno, Yoshiaki; ; Kawada, Koji*; Kawabe, Ryuhei*; *; *; Miyaguchi, Kimihide
PNC TN941 85-130, 65 Pages, 1985/09
Test of sodium fires in an auxiliary building of the fast reactor has been conducted by use of a test rig in which reduced scale models of a sodium pipe, a floor liner, a sodium drain pipe, and a smothering tank were installed to simulate the configuration of fire mitigation systems in the reactor. In the test, a 150kg sodium at temperature of 505 C was spilled from the model sodium pipe at flow rate of 1 /sec for 3 minutes. Then a whole accident sequence that starts from a sodium spill and ends at a self-extiguishment of fire within the smothering tank was studied. From the test results obtained and through their analysis, the following conclusions were drawn. (1)A whole sodium leak and fires accident sequence proceeded as expected in the Monju design, i,e., a spilled sodium was smoothly drained into the smothering tank via the floor liner and the drain pipe, then sodium fire was self-extinguished in the smothering tank. (2)In regard to the model sodium pipe, failures of the thermal insulation jackets due to sodium corrosion and due to generated sodium combustion heat are not found. The thermal insulation jackets kept its original geometries and functioned propely as a barrier to prevent the dispersion of spilled sodium into the atmosphere during the test. No flow blockage of a spilled sodium occured both on the floor Liner and in the drain pipe. Combustion heat of mixed fires (a columnar fire and a pool fire) that occured within an accident cell of the test rig was determined to be 1.6 times of that of a pool fire. This value is not so large as expected and indicates that the mild fires proceeds during the test. (3)With the smothering tank, temperatures data of sodium, steel liner, perlite concrete, and structural concrete were obtained. The data of concretes indicated that the structural concrete was not heated so high as to interfere its structural integrity. A total water released from the concretes per unit surface area of the liner ...