Hydrochemical investigation at the Mizunami Underground Research Laboratory; Compilation of groundwater chemistry data in the Mizunami group and the Toki granite (fiscal year 2013)

Omori, Kazuaki; Hasegawa, Takashi; Munemoto, Takashi; Masuda, Kaoru*; Aosai, Daisuke*; Inui, Michiharu*; Iwatsuki, Teruki

JAEA-Data/Code 2014-019, 121 Pages, 2014/12

JAEA-Data-Code-2014-019.pdf:56.12MB

Japan Atomic Energy Agency has been investigating the groundwater chemistry on excavating the underground facilities as part of the Mizunami Underground research Laboratory (MIU) Project at Mizunami City, Gifu Prefecture, Japan. In this report, we compiled data obtained by geochemical research for groundwater at the MIU in the fiscal year 2013.

Use of experimental results to model experiments; Bio-denitrification under geological disposal conditions

Masuda, Kaoru*; Murakami, Hiroshi*; Kurimoto, Noritaka*; Kato, Osamu*; Kato, Ko*; Honda, Akira

SpringerPlus (Internet), 2, p.339_1 - 339_13, 2013/07

https://doi.org/10.1186/2193-1801-2-339

Some of the low level radioactive wastes from reprocessing of spent nuclear fuels contain nitrates. Nitrates can be present in the form of soluble salts and be reduced by microorganisms. In this study, experiments of the nitrate reduction reaction were conducted using model organic materials purported to exist in underground conditions relevant to geological disposal. A reaction model was developed and verified by running simulations against data obtained from experiments using actual groundwaters and microorganisms. The simulation showed a good correlation with the experimental data and contributes to the understanding of microbially mediated denitrification in geological disposal systems.

Hydrochemical investigation at the Mizunami Underground Research Laboratory; Compilation of groundwater chemistry in the Mizunami group and Toki granite (fiscal year 2010)

Shingu, Shinya; Hagiwara, Hiroki; Masuda, Kaoru*; Iizuka, Masatoshi*; Inui, Michiharu*; Mizuno, Takashi

JAEA-Data/Code 2012-003, 50 Pages, 2012/06

JAEA-Data-Code-2012-003.pdf:4.61MB
JAEA-Data-Code-2012-003-appendix(CD-ROM).zip:226.3MB

Japan Atomic Energy Agency has been investigated the groundwater chemistry on excavating the underground facilities as part of the Mizunami Underground Research Laboratory (MIU) Project at Mizunami City, Gifu Prefecture, Japan. This report compiles data set of the groundwater chemistry obtained at MIU in the fiscal year 2010. In terms of ensuring traceability of data, basic information (e.g. sampling location, sampling date, sampling method, analytical method) and methodology for quality control is described.

Understanding and modeling of chemical transition of nitrate accompanied with corrosion of carbon steel under hyper-alkaline and high nitrate concentration conditions

Honda, Akira; Masuda, Kaoru*; Tateishi, Tsuyoshi*; Kato, Osamu*; Inoue, Hiroyuki*

Zairyo To Kankyo, 60(12), p.541 - 552, 2011/12

https://doi.org/10.3323/jcorr.60.541

Immersion tests and rest potential measurements under hyper-alkaline and high sodium nitrate concentrations were conducted to elucidate and improve model predictions of chemical interactions between carbon steel and nitrate ion in high concentrations of nitrate salt. The modified model can estimate the tendency of time dependent variation of chemical species and of rest potentials.

Chemical transition of nitrate ions accompanied with corrosion of carbon steel under alkaline conditions

Honda, Akira; Kato, Takashi; Tateishi, Tsuyoshi*; Imakita, Tsuyoshi*; Masuda, Kaoru*; Kato, Osamu*; Nishimura, Tsutomu*

Zairyo To Kankyo, 55(10), p.458 - 465, 2006/10

https://doi.org/10.3323/jcorr.55.458

Migration of radioactive material can be affected by the redox condition and the concentration of ligands in the repository of radioactive waste. It is possible that radioactive waste contains nitrate which can affect the migration behavior of radioactive nuclides by both changing the redox condition of the environment and acting as a ligand. On the other hand, several researchers observed the reduction of nitrate ions in ammonia due to the iron. Ammonia has a potential to ligand for radioactive nuclides. Nitrate can also affect the rate of hydrogen gas evolution accompanied by metal corrosion through changing the rest potential of metal by its oxidizing nature. Carbon steel was, therefore, immersed in an aqueous solution of sodium nitrate in a closed system for observing both the chemical interaction between metal and nitrate, and the effect of nitrate on the hydrogen gas evolution rate. The experimental pH range of the solution was 10.0-13.5 which corresponds to the pH range of pore fluid of cementitious material. The cathodic current density shows a Tafel equation type potential dependency in the aqueous solution containing nitrate or nitrite. In spite of the acceleration of cathodic reaction due to the existence of nitrate, the corrosion rates of carbon steel were not accelerated in the nitrate solutions. This fact suggests that the system is controlled by the anodic reaction. The nitrate reduction accompanied by the corrosion of carbon steel is considered to be a series reaction such as nitrate nitrite ammonia. The nitrate reduction reaction compete with the water reduction reaction within the anodic controlled condition, therefore nitrate strongly reduced the hydrogen evolution rate. The generation rates of ammonia were independent of the concentration of nitrate.

An Estimation of the chemical evolution of nitrate due to the metal corrosion and microbiological reaction.

Masuda, Kaoru*; Kato, Takashi; Honda, Akira

JNC TN8400 2005-021, 19 Pages, 2005/09

JNC-TN8400-2005-021.pdf:0.74MB

Uranium and Plutonium are planed to be recovered from spent fuel by the reprocessing in Japan. PUREX method is internationally dominant among the commercial reprocessing plants. PUREX method has been also employed in Japan. The low level liquid waste from PUREX process would contain NO as forms of soluble salts, if the special process for decomposing NO were not adopted. The nitrate is possibly brought within the repository for TRU waste. The generation of H gas and the reduction of NO due to metal corrosion and the generation of N gas due to the microbiological reactions in repository for group3 waste were estimated. The uncertainty on the hydraulic conductivity of cementitious materials, corrosion rates, and microbiological reactions are reflected to the analyses through setting the multiple cases. The analysis results suggested followings. (1) The maximum concentrations of both NO and NH were given in the case where the hydraulic conductivity of cementitious material was assumed to be low ( 5.010 m/s) and the corrosion rate was constant at the initial value (0.1 um/y). (2) The maximum concentration of NH was estimated to be 0.8 mol/dm. (3) The impact of microbiological reaction (denitrifying reaction) was negligible in terms of yield of NO and NH because the proportion of denitrified NO was low. (4) The existence of NO was strongly reduced the evolution of H gas because the nitrate reduction and nitrite reduction dominate the cathodic reactions. (5) The N gas evolution rate due to the denitrifying reaction by microorganisms dominated the total gas evolution rate, if time dependent reduction of corrosion rate was employed. However, the H gas evolution rate in the case is similar to those of N gas due to the denitrifying reaction mentioned above, if time dependent reduction of corrosion rate was neglected

Research on Changes of Nitrate by Interactions with Metals under the Wastes Disposal Environment Containing TRU Nuclide (2)

Wada, Ryutaro*; Nishimura, Tsutomu*; Masuda, Kaoru*; Fujiwara, Kazuo*; Imakita, Tsuyoshi*; Tateishi, Tsuyoshi*

JNC TJ8400 2004-016, 194 Pages, 2004/02

JNC-TJ8400-2004-016.pdf:12.45MB

Research on Changes of Nitrate by Chemical Interactions with Metals under the wastes Disposal Environment Contaioning TRU Nucride

Research on changes of nitrate interactions with metals under the wastes disposal environment containing TRU nuclide (Summary report)

Wada, Ryutaro*; Nishimura, Tsutomu*; Masuda, Kaoru*; Fujiwara, Kazuo*; Imakita, Tsuyoshi*; Tateishi, Tsuyoshi*

JNC TJ8400 2003-080, 153 Pages, 2003/02

JNC-TJ8400-2003-080.pdf:2.63MB

There exists the waste including a nitrate ion as a salt in the TRU waste materials. This nitrate ion can be transferred to the nitrite ion and/or ammonia by reducing materials such as metals in the waste disposal environment, and has the possibility to affect on the disposal environment and nuclide transfer parameters.Therefore, electrochemical tests were conducted to evaluate the reaction rate parameters of the nitrate ion and metals under the low oxygen environment. The long-term reaction test using the glass-seal vessel was also conducted to grasp precisely the nitrate ion transition reaction rate and the gas generation rate caused by the reaction of metal and the nitrate ion coexist solution. (1) Reaction rate constants under various environments were obtained performing the potentiostatic holding tests with the parameters of the solution pH, temperature, and the nitrate and nitrite ion concentrations. The formula of the nitrate ion transition reaction rate was also examined based on these obtained data. (2) Conducting the immersion tests under the environment of the low oxygen and high-pH rainfall underground water site, the long-term reaction rate data were obtained on the reaction products (ammonia, hydrogen gas etc.) of metals (carbon steel, stainless steel and zircaloy etc.) with nitrate ion. The tests under the same conditions as in the past were also conducted to evaluate the test accuracy and error range of the long-term reaction test with the glass-seal vessels.

Research on the Transformation of Nitrate Due to its Chemical Interaction with Metals in TRU Waste Disposal Environmen (Summary Report)

Wada, Ryutaro*; Nishimura, Tsutomu*; Masuda, Kaoru*; Fujiwara, Kazuo*; Imakita, Tsuyoshi*; Tateishi, Tsuyoshi*

JNC TJ8400 2003-077, 156 Pages, 2002/02

JNC-TJ8400-2003-077.pdf:3.63MB

Some TRU wastes contain nitrate ions as salt.The nitrate ions might transform into NO2- and NH3, etc. in the disposal site environment because of reducing agent such as metals, possibly changing disposal site environment or affecting nuclide migration parameters.Therefore, we investigated of chemical interaction between NO3- and metals in a low oxygen environment that corresponds to the disposal site environment.

Development of bio-denitrification model of nitrates under disposal condition

Masuda, Kaoru*; Murakami, Hiroshi*; Kato, Osamu*; Kato, Ko*; Kurimoto, Yoshitaka; Honda, Akira

no journal, , 

A model of nitrate reduction reaction due to microbial activity was developed as a part of an estimation system for the impacts of nitrate on the safety of a geological disposal system for radioactive wastes. Microbial reaction model, which incorporates a relation between nitrate reduction and consumption of organic materials, has been developed on the basis of data available in the literature and experimental results. The model can interpret the experimental results which were acquired using real groundwater.