Ogawa, Toru; Minato, Kazuo; Okamoto, Yoshihiro; Nishihara, Kenji
Journal of Nuclear Materials, 360(1), p.12 - 15, 2007/01
The actinide management has become a key issue in nuclear energy due to increasing proliferation concern and long-term environmental perception. The better way of waste management will be made by system symbiosis: a combination of light-water reactor and fast reactor and/or accelerator-driven transmutation system should be sought. The new recycling technology should be able to achieve good economy with smaller plants, which can process fuels from different types of reactors on a common technical basis. Pyroprocess with the use of molten salts is regarded as the strong candidate for such recycling technology. In JAEA, the first laboratory for the high temperature chemistry of transuranium elements, mainly Am and Cm, has been established. The fundamental data on the molten-salt chemistry of transuranium oxides and nitrides will be combined with the computer code for predicting the molten-salts electrolytic processes.
Minato, Kazuo; Akabori, Mitsuo; Tsuboi, Takashi; Kurobane, Shiro; Hayashi, Hirokazu; Takano, Masahide; Otobe, Haruyoshi; Misumi, Masahiro*; Sakamoto, Takuya*; Kato, Isao*; et al.
JAERI-Tech 2005-059, 61 Pages, 2005/09
An experimental facility called the Module for TRU High Temperature Chemistry (TRU-HITEC) was installed in the Back-end Cycle Key Elements Research Facility (BECKY) of the Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF) for the basic studies of the behavior of the transuranium elements (TRU) in pyrochemical reprocessing and oxide fuels. TRU-HITEC consists of three alpha/gamma cells shielded by steel and polyethylene and a glove box shielded by leaded acrylic resin, where experimental apparatuses have been equipped and a high purity argon gas atmosphere is maintained. In the facility 10 g of Am as well as the other TRU of Np, Pu and Cm can be handled. This report summarizes the outline, structure, performance and interior apparatuses of the facility, and is the result of the joint research between the Japan Atomic Energy Research Institute and three electric power companies of Tokyo Electric Power Co., Tohoku Electric Power Co. and the Japan Atomic Power Co.
Genshikaku Kenkyu, 47(6), p.21 - 30, 2003/06
This paper describes the present state and future prospect of research and development on the separation of long-lived radionuclides from high-level waste (partitioning), which is indispensable for the transmutation of those nuclides. The main items described are composition of high-level waste, selection of elements to be separated, the purpose of partitioining, and development of partitioning process in JAERI.
Nagame, Yuichiro; Hirata, Masaru; Nakahara, Hiromichi
Handbook of Nuclear Chemistry, Vol.2, p.219 - 282, 2003/00
no abstracts in English
; Ishikawa, Hirohisa;
JNC-TN8200 2001-004, 160 Pages, 2001/06
; Nishikawa, Yoshiaki*; ;
JNC-TN8400 2001-002, 23 Pages, 2000/12
The soluble organic compounds generated by radiological degradation of asphalt ( ray) were confirmed as a part of influence of the bituminized waste degradation in the TRU waste repositry. Especially, the influence of the nitrate was focused on. As a result, the concentration of the soluble organic compounds generated by radiological degradation of asphalt (10MGy, ray which is correspond to absorbed dose of asphalt for 1,000,000years) were lower (each formic acid : about 50mg/dm, acetic acid : about 30mg/dm and oxalic acid : about 2mg/dm) than that of the formic acid, the acetic acid and the oxalic acid which Valcke et al. had shown (the influence of the organic at the solubility examination which uses Pu and Am). Moreover, the change in the concentration of TOC and the soluble organic compounds (formic acid, acetic acid and oxalic acid) is little under the existence of nitrate ion. That is, the formic acid and acetic acid which can be organic ligands were generated little by oxidative decomposition of asphalt in the process that nitrate ion becomes nitrite ion by radiation. The influence of the soluble organic compounds by the radiological degradation of the asphalt ( ray) on adsorption and solubility by the complexation of radionuclides in the performance assessment can be limited.
Hidaka, Akihide; Nakamura, Takehiko; Kudo, Tamotsu; Hayashida, Retsu*; Nakamura, Jinichi; Otomo, Takashi; Uetsuka, Hiroshi
JAERI-Conf 2000-015, p.193 - 200, 2000/11
no abstracts in English
Owada, Hitoshi*; ; *; *
JNC-TN8400 2000-027, 19 Pages, 2000/08
Bactch leaching experiments of granite with the artifitial cement leachate and the leachate of low-alkalinity-cement (LW) were carried out to evaluate the effect of the hiperalkaline plume on the environment of the high-level and TRU radioactive waste repository. Dissolution of Si and Al from feldspar included in the granite and precipitation of C-S-H were confirmed from the results of the leaching experiments with artifitial cement leachate. From this result it was found that the composition of sorrounding rock changed. It also suggested that the retardation factor of migration of radionuclides would change. On the contrary, only decrease of concentrations in Si, Al and Ca in the leachate was observed in the experiment with LW. This result might indicate that C-S-H and/or C-A-S-H precipitated as secondary minerals in the LW case. From these results, it was considered that the hiperalkaline plume from the cementitious leachate might caused the change of disposal conditions such as the change in distribution coefficients of rock by precipitation of the secondary mineral and the increase in hydraulic conductivity by the dissolution of rock. On the other hand, the influences of the LW would be comparatively small, because LW and granite might equilibrate in short time.
Mine, Tatsuya*; ;
JNC-TN8430 2000-009, 35 Pages, 2000/07
In the geological disposal system of TRU wastes, nitrogen generation by denitrifying bacteria could provide significant impact on the assessment of this system, because nitrate contained in process concentrated liquid waste might be electron acceptor for denitrifying bacteria. In this study, the activities and tolerance of denitrifying bacteria under disposal condition were investigated. pseudomonas denitrificans as denitrifying bacteria was used. The results showed that Pseudomonas denitrificans had activity under reducing condition, but under high pH condition (PH9.5), the activity of Pseudomonas denitrificans was not detected. It is possible that the activity of Pseudomonas denitrificans would be low under disposal condition.
Kato, Hiroshige*; *; Owada, Hitoshi*; ;
JNC-TN8430 2000-008, 53 Pages, 2000/05
Cementitious materials will be used in TRU waste disposal repository. In such cases, it is considered that the migration of alkaline leachates from cementitious materials, so called high pH plume, will cause dissolution of rock and precipitation of secondary minerals. In addition, the high pH plume will move along the flow of groundwater, so it is predicted that rock formation and components of high pH groundwater vary with time and space. However, time and spatial dependence of the variations of secondary minerals and groundwater components has not been clarified. In order to acquire the data of variations of secondary minerals and groundwater components, we carried out the rock alteration experiments with column method. The crushed granodiorite was filled into 4 meters length column (3.7 cm) and artificial cement leachate (pH=13.3; Na=0,1 mol/l, K=0.1 mol/l, Ca=0.002 mol/l) was streamed at flow rates of 0.1 ml/min for 7 months at 80C. As the result, secondary minerals confirmed on the rock were calcite and C-S-H at upstream of column and C-S-H at mid-downstream. The pH value of the fluid dominated by Na and K did not be decreased by reaction with the rock. In this study, the data relating to the effect of high pH plume on rock over the long term was acquired.
Mine, Tatsuya*; ; ; *; *
JNC-TN8430 2000-003, 33 Pages, 2000/04
On the geological disposal system of the radioactive wastes, the activities of the microorganisms that could degrade the asphalt might be significant for the assessment of the system performance. As the main effects of the biodegradation of the asphalt, the fluctuation of leaching behavior of the nuclides included in asphalt waste has been indicated. In this study, the asphalt biodegradation test was carried out. The microorganism of which asphalt degradation ability was comparatively higher under aerobic condition and anaerobic condition was used. The asphalt biodegradation rate was calculated and it was evaluated whether the asphalt biodegradation in this system could occur. The results show that the asphalt biodegradation rate under anaerobic and high alkali condition will be 300 times lower than under aerobic and neutral pH.
JNC-TN9400 2000-034, 48 Pages, 2000/03
The study and the development to put FBR (Fast Breeder Reactor) to practical use have been doing. So many kinds of technologies are investigated to construct nuclear fuel recycle received to the society. The most important aim of reprocessing has been to extract U and Pu from spent fuels effectively, but, now, the demands for reprocessing are many kinds on nuclear fuel recycle system's construction. These need to be accepted sufficiently. The system that consists of electrolysis, extraction, with molten salt and melting metal, volatilization and condensation using the difference of vapor pressure is suggested, because, differently from LWR (Light Water Reactor), FBR can use the low decontamination factor's fuel. When the engineering scale plant is designed, the dry reprocessing has unsolved problems(ex. process flow) because of less demonstrative scale plants of the dry reprocessing than ones of the wet reprocessing. So the analysis and the estimation of mass balance that is most fundamental in the dry reprocessing system's design need to keep up with the system's alteration (to add new processes etc.) flexibly. This study aim is to develop the mass balance estimation code of dry reprocessing that satisfies the demand mentioned above.
Owada, Hitoshi*; ; Iriya, Keishiro*; *
JNC-TN8400 99-057, 43 Pages, 2000/03
Cementitious materials are considered as candidate materials for the geological disposal of high-level radioactive waste and TRU waste. As the pH and the Ca content of leachate from the cementitious materials are high, the host rock and the buffer-material would be degraded by the leachate in the long-term. Therefore, transport properties and parameters such as solubilities and distribution coefficients of radionuclides would be changed and affect the performance of the repository. In order to dissolve this "High pH plobrem", the use of a low alkalinity cement is considered for the disposal. In this study, we summarized the necessity of the low alkalinity cement, and developed the approach of the low alkalinization of cement. And, the following were carried out in this study : A leaching test of cement paste, a fluid test of the mortar and a installation test of the concrete to the trial structure. From the leaching test using the cement paste, we confirmed that we were able to obtain the low alkalinity cement (HFSC) by addition of pozzolanic materials such as silica-fume and flyash. From the result of the fluid test of the mortar, we chose the cement for the practicability evaluation. The practicability of low alkalinity concrete was evaluated by installation test to the trial structure.As a result of these examinations, we proved that the pH value of the leachate from the cementitious material was reduced by adding SF and FA to Portland cement. Simultaneously, SF and FA had to be added in order to obtain the good workability. In addition, workability and mechanical strength of the cement which SF and FA were added are almost equivalent to the ordinary Portland cement. The results shows that the HFSC has high practicability.
JNC-TJ8400 2000-050, 47 Pages, 2000/03
In support of the safety assessment of geologic disposal of high levcl radioactive wastes, the solubility of transuranium elements was studied. The solubility of PuOxHO was measured undcr a reducing condition, and the solubility product K and the stability constant of Pu(OH) were obtained. The obtained K value was found to be much smaller than that predicted by Rai et al. from its dependence on ionic radius. Also, the solubility of PuO3 xHO was measured under an oxidizing condition and the solubility product K was obtained. In the analysis of hydrolysis constants of actinide ions, it was found that the systematic trend of the hydrolysis constants was well explained by the hard sphere model considering the effective charges of actinide ions.
Amano, Hikaru; Ueno, Takashi; Arkhipov, N.*; Paskevich, S.*; Onuma, Yoshikazu*
Proceedings of 10th International Congress of the International Radiation Protection Association (IRPA-10) (CD-ROM), 6 Pages, 2000/00
no abstracts in English
Aoyagi, Takayoshi*; ; Tanaka, M.*; Okutsu, Kazuo*
JNC-TN8400 99-058, 55 Pages, 1999/11
For the emplaced waste in TRU waste disposal facility, it may have the void for waste bodies it. And, generating void which accompanies those component elution in concrete pit and filler in which the cement material becomes the candidate material is assumed. It is considered that the security of the diffusion control in the bentonite is not done when these voids collapsed, and when it generated the volume change inside the buffer material (bentonite). The imperfect blockage of the void by not obtaining, the sufficient swelling pameability swelling bentonite is a cause on this. Then, volume change of the bentonite inside is analyzed in this study under the conservative estimation. And the following are tested: Self-sealing, maximum swelling rate, density distribution change of the batonite. Evaluation of the engineered barrier system for volume change from the result was carried out. Prior to the evaluation, generating void was calculated based on the conservative estimation. The density of the buffer material as it assumed the blocking by buffer material uniformly awelling using this calculated data, was obtained. By the permeability got from existing research result which shows the relationship between density and permeability of the bentonite, it was confirmed to become diffusion control in the buffer material inside, in existing engineered barrier specification. Next, it was tested, when the conservative void of the superscription was assumed, in order to confirm whether it does the security, as permeability necessaly for maintaining diffusion control, puts it for the swelling of actual bentonite. As the result, it was possible to confirm sufficient swelling performance in order to do the security of the diffusion control in Na-bentonite. However, the swelling performance greatly lowered by comparing Na-bentonite in Ca-bentonite with under 1/6. The increase of the permeability not do the security of the diffusion control, when it was based on void quantity ...
Amano, Hikaru; Matsunaga, Takeshi; Nagao, Seiya; *; Watanabe, Miki*; Ueno, Takashi; Onuma, Yoshikazu*
Organic Geochemistry, 30, p.437 - 442, 1999/00
no abstracts in English
Sakamura, Y.*; Inoue, Tadashi*; Shirai, Osamu; Iwai, Takashi; Arai, Yasuo; Suzuki, Yasufumi
Proc. of the Int. Conf. on Future Nuclear Systems (GLOBAL'99)(CD-ROM), 8 Pages, 1999/00
no abstracts in English
Amano, Hikaru; Hanzawa, Yukiko; Watanabe, Miki*; Matsunaga, Takeshi; Ueno, Takashi; Nagao, Seiya; Yanase, Nobuyuki; Onuma, Yoshikazu*
Proceedings of OECD/NEA Workshop on Evaluation of Speciation Technology, p.211 - 218, 1999/00
no abstracts in English