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Takai, Shizuka; Namekawa, Masakazu*; Shimada, Taro; Takeda, Seiji
IEEE Transactions on Nuclear Science, 69(7), p.1789 - 1798, 2022/07
Times Cited Count：0 Percentile：0.01(Engineering, Electrical & Electronic)To reduce a large amount of contaminated concrete rubble stored in the Fukushima Daiichi Nuclear Power Station site, recycling low-radioactivity rubble within the site is a possible remedy. To promote recycling while ensuring safety, not only the average radioactivity but also the radioactivity distribution of concrete rubble should be efficiently evaluated because the details of rubble contamination caused by the accident remain unclear and likely include hotspots. However, evaluating inhomogeneous contamination of thick and/or dense materials is difficult using previous measurement systems, such as clearance monitors. This study experimentally confirmed the potential applicability of image reconstruction algorithms for radioactivity distribution evaluation in concrete rubble filled in a chamber. Radiation was measured using plastic scintillation fiber around the chamber (50 
50 40 cm
). Localized hotspots were simulated using standard sources of 
Cs, which is one of the main nuclides of contaminated rubble. The radioactivity distribution was calculated for 100 or 50 voxels (voxel size: (10 cm) or 10 10 20 cm) constituting the chamber. For 100 voxels, inner hotspots were undetected, whereas, for 50 voxels, both inner and surface hotspots were reconstructible. The distribution evaluated using the maximum likelihood expectation maximization algorithm was the most accurate; the average radioactivity was estimated within 70% accuracy in all seven cases.
Yokota, Wataru
Kigyo Sapoto Gumma, P. 12, 2004/07
no abstracts in English
Sato, Haruo
JNC TN8410 2001-003, 40 Pages, 2001/01
JNC-TN8410-2001-003.pdf:1.13MB
A program (TDROCK1.FOR) for simulation and analysis of through-diffusion experiments for a single layer of diffusion media was developed. This program was made by Pro-Fortran language, which was suitable for scientific and technical calculations, and relatively easy explicit difference method was adopted for an analysis. In the analysis, solute concentration in the tracer cell as a function of time that we could not treat to date can be input and the decrease in the solute concentration as a function of time by diffusion from the tracer cell to the measurement cell, the solute concentration distribution in the porewater of diffusion media and the solute concentration in the measurement cell as a function of time can be calculated. In addition, solution volume in both cells and diameter and thickness of the diffusion media are also variable as an input condition. This simulation program could well explain measured result by simulating solute concentration in the measurement cell as a function of time for case which apparent and effective diffusion coefficients were already known. Based on this, the availability and applicability of this program to actual analysis and simulation were confirmed. This report describes the theoretical treatment for the through-diffusion experiments for a single layer of diffusion media, analytical model, an example of source program and the manual.
Okamoto, Koji*; *
JNC TY9400 2000-016, 90 Pages, 2000/06
JNC-TY9400-2000-016.pdf:2.53MB
no abstracts in English
;
JNC TN4400 99-002, 192 Pages, 1999/03
The tritium transport analysis code, TTT, has been validated using data from the low power test of Monju, and then its behaviour at along term full power operation of Monju in future has been estimated, when the estimated transport and distribution of tritium in the reactor system has been also compared with the result in Joyo and Phenix, which had been already experienced long term operations. The TTT code had been develpped using the tiritium and hydrogen transport model proposed by R. Kumar, ANL, and had been applied to the evaluation in Monju design work. After then, futhermore, the code has been improved using the data from long term operation of Joyo with MK-II core, and in this work the code has been validated for the first time for Monju data. The results from this work are as follows; (1)Comparison of the best fitted tritium source rates from cores in Joyo, Phenix and Monju makes an estimation of the major source from control rods, (2)The calculated tritium concentration in each medium for cooling and its change is a reasonable agreement to the measured, C/E=1.1, (3)The cover gas transport model cosidering isotopic exchange of H and H can reproduce reasonably the measured concentration distirbution of tritium in sodium and cover gas, (4)The tritium concentration in secondary sodium of Monju was about l/50 times as much as the primary one, which shows the acceraration effect on cold tarapping of tritium due to coprecipitation with permeated hydrogen through Evaporater (EV) heat conduction tube walls. The tritium cold trapping efficiency was estimated to be 1 for coprecipitation with hydrogen and 0.3 for isotopic exchange, respectively, (5)Tritium transport and distribution for along term full power operation of Monju in future was estimated, which could involve a excess factor to 4 at the maximum. The tritium concentration in sodium and Steam Generator (SG) water will be substantially saturated after somthing like 10 years full power operation, ...
Watanabe, Ryuzo*
PNC TJ9601 98-005, 85 Pages, 1998/03
To fabricate a long life fuel cladding tubes for the fast breeder reactor, the concept of functionally graded material was applied for the material combination of molybdenum/stainless steel/ titanium, in which titanium is placed at the inner side to withstand against fission products and neutron irradiation, and molybdenum at the outer side to withstand corrosion by liquid sodium coolant. Slurry dipping method was employed for the processing because of its capability of shape forming and microstructural control. The graded layers of titanium and molybdenum were formed on both sides of stainless steel substrate according to an optimum composition profile for the thermal stress reduction. Such graded layers were successfully formed by slurry dipping. Dispersion, sedimentation, viscosity, rheology, as well as yield value, of the slurries were investigated in detail inconnection with properties of dispersion medium, dispersion reagent, binder and raw powders. Low- and high-viscosity slurries were investigated to enlarge a possibility of film thickness control. For the low-viscosity slurry it is necessary to suppress the sedimentation of dispersion particles, while for the high-viscosity slurry it turned out to be important to clarify the flow characteristics of the slurry for the determination of the yield value, which is needed for the precise control of the dip-coated layer thickness. The forming conditions were determined for the low-viscosity slurry in taking sedimentation rate and sedimentation height as measures of slurry stability and dispersion, respectively. It was confirmed that slow sedimentation and low sedimentation height gave reproducible film forming. The high-viscosity slurry was free from sedimentation, and the control of the film thickness with viscosity and yield value was rather easier. The consolidation Process of the dip-coated layer, including drying and debinding, followed conventional powder metallurgical techniques, with particular ...
; ; *; *; Masaki, Toshio; Kobayashi, Hiroaki; *
PNC TN8410 98-041, 185 Pages, 1998/02
The 9
test of Joule-Heated Cylindrical Electrode Melter - Engineering Scale (JCEM-E9 Test) was carried out from June to July 1996, as a part of the development program on an advanced glass melter. The principal purpose of the test was to estimate the effect of noble metal on operation of the melter with simulated high-level liquid waste. Besides, we also evaluated the basic operational characteristics with corrosion of electrodes, qualities of produced glass etc. JCEM-E is an electric glass melter with an internal electrode and an external electrode in a subsidiary furnace. The internal electrode is a rod inserted in the center of external electrode that is a cylindrical tank. The glass is melted by conducting electric current through the molten glass between the internal and external electrodes. The subsidiary furnace is composed of multi-layer refractories inside a metallic casing and is equipped with the resistance heaters. Melting surface area is 0.35 m
that i8 approximately half of 0.66 m of TVF melter. In the test, 13 batches of glass was produced and total weight of produced glass was 3663kg. As a result, The maximum processing rate of JCEM-E with simulated HLLW including noble metals was 4.20
5.60kg/h, and decreased to less than 80 percent compared with JCEM-E8 Test with non-noble metals HLLW. It was considered that the decrease of the rate arose from concentration of current due to non-uniform distribution of noble metals in molten glass. Judging from the balance of feed and draining, and as a consequence of the observation inside the melter after the test, the draining of noble metals from the nozzle was good. As for the quality of glass produced in the test, properties of concern were comparable with those of standard glass of TVF.
; Yamaguchi, Akira
PNC TN9410 98-028, 33 Pages, 1997/12
The safety analysis of FBR plant system for sodium leak phenomena needs to evaluate the deposition of the aerosol particle to the components in the plant, the chemical reaction of aerosol to humidity in the air and the effect of the combustion heat through aerosol to the structural component. For this purpose, ABC-INTG (Aerosol Behavior in Containment-INTeGrated Version) code has been developed and used until now. This code calculates aerosol behavior in the gas area of uniform temperature and pressure by 1 cell-model. Later, however, more detailed calculation of aerosol behavior requires the installation of aerosol model into multi-cell thermal hydraulic analysis code AQUA. AQUA can calculate the carrier gas flow, temperature and the distribution of the aerosol spatial concentration. On the other hand, ABC-INTG can calculate the generation, deposition to the wall and flower, agglomeration of aerosol particle and figure out the distribution of the aerosol particle size. Thus, the combination of these two codes enables to deal with aerosol model coupling the distribution of the aerosol spatial concentration and that of the aerosol particle size. AQUA and ABC-INTG were developed separately, therefore, several subroutine were modified and composed. Especially, the interface program which exchanges data between these two codes is important to execute transient calculation. This report describes aerosol behavior model, how to install the aerosol model to AQUA and new subroutine equipped to the code. Furthermore, the test calculations of the simple structural model were executed by this code, appropriate results were obtained. Thus, this code has prospect to predict aerosol behavior by the introduction of coupling analysis with multi-dimensional gas thermo-dynamics for sodium combustion evaluation.
Ohara, Kinichi*
PNC TJ1676 97-001, 221 Pages, 1997/03
None
*; *; *
PNC TJ9614 94-001, 59 Pages, 1994/03
Crossflow of a two-phase mixture between vertical subchannels is subdivided into three components in the literature; turbulent mixing, void drift and diversion crossflow. Of these, turbulent mixing alone occurs in an equiliblium flow, in which flow rates of both phases in each subchannel do not change in the axial direction. In a general non-equilibrium flow, however, all three components occur simultaneously. In this report, effect of pressure differential between subchannels on flow redistribution process along the channel axis has been studied experimentally. In the experiment, a multiple channel, consisting of two identical circular subchannels of 16 mm I.D., were used as a test channel. And, air and water were introduced unevenly into the two subchannels at the inlet to get several non-equilibrium flows with and without the pressure differential between subchannels. For each flow, we have obtained the axial distributions data of pressure differential between the subchannels, the air and water flow rates, the void fractions, and the tracer concentrations for both phases when gas and liquid tracers were injected into one of the two subchannels. From these experimental data, we have estimated lateral velocities of the air and water corresponding to each crossflow component, and analyzed the effect of the pressure differential on the lateral velocities.
*; *; *; Iida, Takao*; *; *
PNC TJ1545 94-003, 39 Pages, 1994/03
no abstracts in English
Odo, Toshihiro;
PNC TN9420 92-005, 83 Pages, 1992/04
This report introduces the nuclear instrumentation system and major R&D (research and development) activities using radiation measurement techniques in Experimental Fast Reactor "JOYO". In the introduction of the nuclear instrumentation system, following items are described; (1)system function (2)roles as a reactor plant equipment (3)specifications and charactelistics of neutron detectors, (4)construction and layout of the system. For reactor dosimetry at various irradiation tests and surveillance tests, multi-foil method employed in "JOYO", neutron fluence evaluation using activation foils and HAFM (Helium Accumulation Fluence Monitor) under development are described briefly. The failed fuel detection system and some experimental equipments using radiation measurement techniques are also introduced here with main results obtained by a series of fuel failure simulation experiments. In addition, following R&Ds are picked up as some examples based on radiation measurement technology; (1)burn-up measurement of spent fuel subassembly (2)measurement and evaluation of radiation source distributions (radioactive corrosion products)
; Miyoshi, Yoshinori; Tachimori, Shoichi
JAERI-M 91-184, 31 Pages, 1991/11
no abstracts in English
Fumizawa, Motoo; Ogawa, Masuro; Hishida, Makoto; Okamoto, Koji*
FLUCOME-91, p.333 - 338, 1991/00
no abstracts in English
Fumizawa, Motoo; Hishida, Makoto; Kunugi, Tomoaki
JAERI-M 89-065, 37 Pages, 1989/05
no abstracts in English
; Yamamoto, Tadatoshi; Wadachi, Yoshiki
JAERI-M 85-111, 16 Pages, 1985/08
no abstracts in English
