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Yoshida, Michihiro; Suzuki, Satoshi*; Sukegawa, Yasuhiro*; Miyo, Hiroaki
JNC TN8440 2000-021, 180 Pages, 2000/10
JNC-TN8440-2000-021.pdf:42.37MB
At outside waste storage pits, containers for storage of wastes corroded and were flooded, and it was confirmed on August 26, 1997. Confirmation of contamination of the pits outskirts, installation of sheets to prevent rainwater from flowing into the pits, drawing stay water were executed, promptly. Design and authorization works of the work house and waste treatment devices to take out wastes of the pits were executed too. After construction of the work house, taking out wastes of the pits started, and finished on April 10, 1998. Investigations of the inflow point of rainwater and leak of stay water were executed next. The results were reported to Science and Thechnology Agency (STA), adjoining authorities on December 21, 1998. After decontamination of the pits inner walls to background level of the radioactivity which included general concrete, control area was removed, and the pits were closed by concrete. Measures of closing of the pits were prepared from the middle of August, 1999, and dismantlement of unnecessaly instruments started. Decontamination of the pits started fiom the beginning of September, 1999. The above works finished on June 30, 2000. After decontamination of the pits, STA, adjoining authorities confirmed the circumstances. Work pouring concrete into the pits was executed three times (three levels), and finished on August 31, 2000. In addition to above, the amount of concrete poured into the pits was about 1,200 m
. This report compiled the photographs of the works from confirmation of stay water at August, 1997 by finish of measures of closing of the pits at September, 2000.
; ; ; Iguchi, Yukihiro; Matsui, Yuji;
JNC TN3410 2000-014, 43 Pages, 2000/09
JNC-TN3410-2000-014.pdf:2.37MB
None
Miyabe, Kenjiro; Takasaki, Koji; Yasunaga, Hideo*; Izumi, Yuichi*
JNC TN8420 2000-007, 100 Pages, 2000/08
JNC-TN8420-2000-007.pdf:7.66MB
The commercial detergents, which are cleansing cream, shampoo, neutral detergent, etc., were examined in order to select the body cleaners that are substitutes for the titanium dioxide paste. JNC entrusted Japan Environment Research Corporation Limited with these examinations since 1997. In 1997 and 1998, the commercial detergents were examined for Ce-144, Cs-137 and Ru-106. In 1999, 22 detergents were examined for Co-60 from the result of the past examinations. In this examination, the radioactive solution of Co-60 was dropped on the pig-skin samples. These samples were washed with each detergent after 5 minutes and 40 minutes. The decontamination factors of detergents were estimated by the radioactive ratio of the samples before and after washing. As a result of this examination, the decontamination factors for Co-60 was the same as the decontamination factors for Ce-144 and Cs-137, and 11 detergents were nominated as the cleaner that have the decontamination factor more than that of titanium dioxide paste.
Otagaki, Takao*;
JNC TJ8420 2000-016, 427 Pages, 2000/03
JNC-TJ8420-2000-016.pdf:18.18MB
no abstracts in English
;
JNC TJ8420 2000-013, 96 Pages, 2000/03
JNC-TJ8420-2000-013.pdf:6.04MB
no abstracts in English
;
JNC TJ8420 2000-010, 171 Pages, 2000/03
JNC-TJ8420-2000-010.pdf:5.34MB
no abstracts in English
Tochiyama, Osamu*
JNC TJ8400 2000-044, 53 Pages, 2000/02
JNC-TJ8400-2000-044.pdf:1.41MB
To estimate the polyelectrolyte effect and the effect of the heterogeneous composition of humic acids, the complex formation constants of Eu(III) and Ca(II) with Aldrich humic acid and polyacrylic acid were obtained, for Eu(10
to 10
M) by solvent extraction with TTA and TBP in xylene, for Ca (10
M) with TTA and TOPO in cyclohexane and for Ca(10
M) by using ion-selective electrode. By defining the apparent formation as 
= [MR
]/([M][R]), where [R] denotes the concentration of dissociated functional group, [M] and [MR] denote the concentration of free and bound metal ion and pcH is defined as-log[H], the values of log have been obtained at pcH 4.8 - 5.5 in 0.1 - 1.0M NaClO
and NaCl. Log of Eu-humate varied from 5.0 to 9.3 and that of Ca-humate from 2.0 to 3.4..For both humate and polyacrylate, log increased with pcH or with the degree of dissociation. The increase in the ionic strength O.1 to 1.0 M decreased the log, the decrease in log of Eu(III)-humate is 1.6, that of Eu(III), polyacrylate 0.7, that of Ca(II)-humate 1.9 and that of Ca(II)-polyacrylate 1.2. While the increase in the metal ion produced no effect on log of polyacrylate, log of humate decreased. Depending on the concentration of Eu(III), the coexistence of Ca(II) reduced log of humate by 0 to 0.8. The dependence of log of humate on the metal ion concentration suggests the coexistence of strong and weak binding sites in the hmnic acid.
; ; ; Tanimoto, Kenichi
PNC TN9410 97-071, 69 Pages, 1997/07
In order to decrease radioactivity of high-level radioactive wastes to low-level (lower than 500 
Sv/h), the dry-ice blasting method has been developing. This method can decontaminate radioactive wastes up to 10
in decontamination factor, and can minimize the secondary generated wastes. The barrel type method can decontaminate smaller solid wastes with preventing the scattering of the wastes due to blast pressure. In this work, application test was conducted to improve the decontamination capability of the barrel type method, with using the improved barrel device. Results are as follows. (1)Stirring ability of the barrel device was improved by installing plates in the barrel. Four plates with 10mm in height were better for optimal stirring. (2)Reciprocating of the blasting nozzle stabilized decontamination capability of the barrel device. Forty per a minute in reciprocation rate of the nozzle was better. (3)Decontamination capability was examined with using test pieces coated with the cesium molybdate, which was simulating the typical contamination of radioactive waste. As a result, 80% of contamination was removed by the optimized barrel type method. (4)Dust collector was frozen within a few minutes, and exhaust flow rate was decreased by about 15%. However, by exhausting room temperature air, dust collector was unfrozen, and the flow rate could be recovered. (5)Decontamination capabilities of two types of dry ice pellets were compared. They were made by an oil hydraulic pressing or a roller pressing. Former pellet was three times as capable as latter one.
; ; ; Tanimoto, Kenichi
PNC TN9410 97-061, 73 Pages, 1997/05
In order to decrease radioactivity of high-level radioactive wastes to low-level (lower than 500 Sv/h), the dry-ice blasting method has been developing. This method can decontaminate radioactive wastes up to 10 in decontamination factor, and can minimize the secondary generated wastes. However, the method was not applicable to smaller and lighter objects because the objects scatter with the blasting flow. Two types of decontamination method, which are a barrel type- and a vacuum type- dry ice blasting methods, therefore, were planned. The barrel type method can decontaminate smaller solid wastes with preventing the scattering of the wastes by blast pressure. The vacuum type method has advantages to localize and collect the removed contamination from larger wastes. In this work, their basic efficiency on decontamination were investigated experimentally using painted specimens simulating contaminated wastes. Results are as follows. (1)In the experiment on the barrel type method, distance between blast nozzle and specimens, blast pressure, blast duration and rotational speed of barrel were changed within a range of 70
250 mm, 715kgf/cm, 90300 second and 530 r.p.m. respectively. Decontamination efficiencies were determined with measuring differential weight of specimens between before and after the experiment. As the result, it was clarified that the suitable distance was 150mm, that the efficiency wasn't improved in the pressure more than 10kg/cm, that the rotational speed was not so dominant, and that the dominant parameter on the efficiency was the duration. The decontamination efficiency rose up with the duration within 300 sec. (2)In the experiment on the vacuum type method, blast pressure and blast duration were changed within a range of 46kgf/cm, and 60180 second, respectively. Top of a vacuum cover was also opened or closed. Decontamination efficiencies were determined with measuring area of ...
; ; ; ; ; ;
PNC TN9410 96-235, 258 Pages, 1996/03
The chemical decontamination technique has been developed in order to remove the crud adhering to the surface of the components constructing the primary coolant system, as a part of the measure to decrease the exposure in the annual inspection. The technique has been already applied to the prototype reactor "Fugen", in the core of which the fuel assemblies were not loaded. The chemical decontamination, for the core in which the fuel assemblies are loaded, has been planned for the purpose of improving the utilization factor. It is necessary to confirm, through the test before putting the plan into practice, that the decontamination reagent does not exert a bad influence upon the components constructing the fuel assembly. This report describes the test results which have been carried out so as to investigate the influence of the reagent on the components constructing the fuel assembly. The outline of the results is as follows: (1)The susceptibility to stress corrosion cracking of the chemical decontamination treatment and the residual decontamination reagent on the components constructing the fuel assembly is low enough. (2)The chemical decontamination treatment and the residual decontamination reagent do not exert a bad influence upon the integrity of the fuel assembly concerning the fuel rod holding function of the spacer and the characteristics of the fretting wear caused on the fuel claddings.