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JAEA Reports

Stabilization treatment of nuclear fuel material contained with organic matter

Senzaki, Tatsuya; Arai, Yoichi; Yano, Kimihiko; Sato, Daisuke; Tada, Kohei; Ogi, Hiromichi*; Kawanobe, Takayuki*; Ono, Shimpei; Nakamura, Masahiro; Kitawaki, Shinichi; et al.

JAEA-Testing 2022-001, 28 Pages, 2022/05

JAEA-Testing-2022-001.pdf:2.33MB

In preparation for the decommissioning of Laboratory B of the Nuclear Fuel Cycle Engineering Laboratory, the nuclear fuel material that had been stored in the glove box for a long time was moved to the Chemical Processing Facility (CPF). This nuclear fuel material was stored with sealed by a polyvinyl chloride (PVC) bag in the storage. Since it was confirmed that the PVC bag swelled during storage, it seems that any gas was generated by radiolysis of the some components contained in the nuclear fuel material. In order to avoid breakage of the PVC bag and keep it safety for long time, we began the study on the stabilization treatment of the nuclear fuel material. First, in order to clarify the properties of nuclear fuel material, radioactivity analysis, component analysis, and thermal analysis were carried out. From the results of thermal analysis, the existence of organic matter was clarified. Then, ion exchange resin with similar thermal characteristics was selected and the thermal decomposition conditions were investigated. From the results of these analyzes and examinations, the conditions for thermal decomposition of the nuclear fuel material contained with organic matter was established. Performing a heat treatment of a small amount of nuclear fuel material in order to confirm the safety, after which the treatment amount was scaled up. It was confirmed by the weight change after the heat treatment that the nuclear fuel material contained with organic matter was completely decomposed.

Journal Articles

Seven cysteine-deficient mutants depict the interplay between thermal and chemical stabilities of individual cysteine residues in mitogen-activated protein kinase c-Jun N-terminal kinase 1

Nakaniwa, Tetsuko*; Fukata, Harumi*; Inoue, Tatsuya*; Goda, Masaki*; Nakai, Ryoko*; Kirii, Yasuyuki*; Adachi, Motoyasu; Tamada, Taro; Segawa, Shinichi*; Kuroki, Ryota; et al.

Biochemistry, 51(42), p.8410 - 8421, 2012/10

 Times Cited Count:17 Percentile:43.17(Biochemistry & Molecular Biology)

Protein kinase is a vital drug target for the treatment of a wide range of diseases. To investigate the effect of cysteine mutation on the function, stability and structure of kinase, free cysteines of c-Jun N-terminal kinase 1 (JNK1) were systematically removed by mutation. Two cysteine-destructed mutants in which three (M3) and seven (M7) cysteine residues are removed, yielded about 5 and 2 times than wild type JNK-1 (M0). SDS PAGE analysis showed that the aggregation was less in the case of M3 and M7. Thermal unfolding experiment of M0, M3 and M7 using by differential scanning calorimetry proceeded at least three state unfolding. Crystal structure of the M3 mutant was determined to 2.6 ${AA}$ resolution, which was identical to that of the wild-type. Consequently, due to the highest yield, its improved stability against aggregation and its structural similarity to the wild type, the M3 mutant is suitable for the use of further characterization of its function and structure.

Journal Articles

Non-destructive evaluation methods for degradation of IG-110 and IG-430 graphite

Shibata, Taiju; Sumita, Junya; Tada, Tatsuya; Hanawa, Satoshi; Sawa, Kazuhiro; Iyoku, Tatsuo

Journal of Nuclear Materials, 381(1-2), p.165 - 170, 2008/10

 Times Cited Count:14 Percentile:66.83(Materials Science, Multidisciplinary)

The lifetime extension of in-core graphite components is one of the key technologies for the VHTR. The residual stress in the graphite components caused by neutron irradiation at high temperatures affects their lifetime. Although oxidation damage in the components would not be significant in reactor normal operation, it should be checked as well. To evaluate the degradation of the graphite components directly by non-destructive way, the applicability of the micro-indentation and ultrasonic wave methods were investigated. The fine-grained isotropic graphites of IG-110 and IG-430, the candidate grades for the VHTR, were used in this study. The following results were obtained. (1) The micro-indentation behavior was changed by applying the compressive strain on the graphite. It suggested that the residual stress would be measured directly. (2) The change of ultrasonic wave velocity with 1 MHz by the uniform oxidation could be evaluated by the wave-propagation analysis with wave-pore interaction model. (3) The trend of oxidation-induced strength degradation on IG-110 was expressed by using the proposed uniform oxidation model. The importance of the un-uniformity consideration was indicated.

Journal Articles

Development of non-destructive evaluation methods for degradation of HTGR graphite components

Shibata, Taiju; Sumita, Junya; Tada, Tatsuya; Sawa, Kazuhiro

Journal of Nuclear Materials, 381(1-2), p.204 - 209, 2008/10

 Times Cited Count:7 Percentile:44.69(Materials Science, Multidisciplinary)

To develop the non-destructive evaluation methods for degradation of HTGR graphite components, the applicability of the micro-indentation method to detect the residual stress was studied. The IG-110 and IG-430 graphites were used. (1) The residual stress in a graphite block at the HTTR in-core condition was analyzed. For the components in the VHTR which would be used at much severer condition, the development of lifetime extension methods was suggested as an important subject. (2) Micro-indentation behavior at stress free condition was investigated with some indenters. The spherical indenter R0.5 mm with indentation load of 5 and 10 N was selected to detect the specimen surface condition sensitively. (3) The relationship between the average indentation depth and compressive stress of the specimen was expressed by an empirical formula. It would be possible to evaluate the residual stress by the indentation. It is necessary to assess the data with statistic method in the future study.

JAEA Reports

Development of oxidation damage evaluation method for HTGR graphite component by ultrasonic-wave propagation characteristics, 1 (Contract research)

Tada, Tatsuya; Shibata, Taiju; Sumita, Junya; Sawa, Kazuhiro

JAEA-Research 2007-079, 22 Pages, 2008/01

JAEA-Research-2007-079.pdf:13.34MB

Graphite materials used for in-core components of High Temperature Gas-cooled Reactor are gradually oxidized by quite small amount of impurities in primary coolant during long term operation. The oxidation damage is addressed one of crucial factors to determine their lifetime, and it is important to evaluate the damage for components lifetime extension. Since ultrasonic-waves are propagated through interactions with pores in porous ceramics including graphite, it is possible to evaluate the porous condition by propagation characteristics such as velocity and attenuation. We are now developing the oxidation damage evaluation method non-destructively by the wave propagation characteristics. This report shows evaluation formulas to evaluate uniform oxidation condition of graphite. They are obtained experimental data of wave propagation characteristics for parametrically oxidized IG-110 and IG-430 graphite specimens.

Journal Articles

Oxidation damage evaluation by non-destructive method for graphite components in High Temperature Gas-cooled Reactor

Shibata, Taiju; Tada, Tatsuya; Sumita, Junya; Sawa, Kazuhiro

Journal of Solid Mechanics and Materials Engineering (Internet), 2(1), p.166 - 175, 2008/00

To develop non-destructive evaluation methods for oxidation damage on graphite components in High Temperature Gas-cooled Reactors (HTGRs), the applicability of ultrasonic wave and micro-indentation methods were investigated. IG-110 and IG-430 graphites, candidates for Very High Temperature Reactor (VHTR), were uniformly oxidized for experiments. (1) Ultrasonic wave velocities were decreased with increasing the oxidation. It can be expressed empirically by exponential formulas to oxidation weight loss. (2) A wave propagation analysis with a wave-pore interaction model showed slightly less velocity reduction than experimental data of the oxidized IG-110. The possibility of the non-uniform oxidation effect was suggested. (3) Although micro-indentation characteristics were changed to show oxidation-induced degradation, it is necessary to assess the variation of the test data with statistic method to specify the oxidation damage in the next study.

JAEA Reports

Development of evaluation method of residual stress for graphite component of HTGR by micro-indentation method, 1 (Contract research)

Sumita, Junya; Shibata, Taiju; Tada, Tatsuya; Sawa, Kazuhiro

JAEA-Research 2007-073, 17 Pages, 2007/11

JAEA-Research-2007-073.pdf:5.72MB

In High Temperature Gas-cooled Reactor (HTGR), graphite materials are used as core internal structural components. The neutron irradiation and thermal gradient induce residual stress of graphite components which is a crucial factor to determine the lifetime of them. It is hence important to measure and assess the stress for lifetime extension of the components. Since the residual stress gives characteristics change to the micro-indentation behavior, it is possible to evaluate the residual stress to measure indentation depth. Therefore, in order to evaluate the change of residual stress of graphite components non-destructively, we are now developing the indentation method to evaluate it. This report showed the relationship between indentation depth and residual stress based on experimental data obtained by changing the stress condition of graphite specimen parametrically.

Journal Articles

Analytical study on micro-indentation method to integrity evaluation for graphite components in HTGR

Sumita, Junya; Hanawa, Satoshi; Shibata, Taiju; Tada, Tatsuya; Iyoku, Tatsuo; Sawa, Kazuhiro

Proceedings of 14th International Conference on Nuclear Engineering (ICONE-14) (CD-ROM), 8 Pages, 2006/07

An analytical study on micro-indentation method to integrity evaluation for graphite components was carried out. The indentation method is used as simplicity test to measure mechanical properties of materials. This method is thought to be applicable to evaluate the residual stress from the relationship between indentation load and indentation depth. In this study, in order to confirm the applicability of the micro-indentation method for lifetime evaluation of the graphite component, indentation load-depth behavior under stress/strain condition was evaluated taking account of the specified minimum ultimate strength of IG-110 graphite. Moreover, analytical investigations of indentation load-depth behavior for oxidized graphite and oxidized graphite with residual strain were also carried out. As a result, it can be said that the indentation method is potentially applicable to evaluate the integrity of graphite components.

Oral presentation

Development of non-destructive damage evaluation method for nuclear graphite

Shibata, Taiju; Sumita, Junya; Hanawa, Satoshi; Tada, Tatsuya; Sawa, Kazuhiro; Ishihara, Masahiro; Iyoku, Tatsuo

no journal, , 

no abstracts in English

Oral presentation

Development of evaluation techniques for residual stress and oxidation damage on graphite components in nuclear reactors

Shibata, Taiju; Sumita, Junya; Hanawa, Satoshi; Tada, Tatsuya; Sawa, Kazuhiro; Iyoku, Tatsuo

no journal, , 

no abstracts in English

Oral presentation

Investigation on lifetime extension and waste reduction methods for graphite components

Sumita, Junya; Hanawa, Satoshi; Shibata, Taiju; Tada, Tatsuya; Iyoku, Tatsuo; Sawa, Kazuhiro

no journal, , 

In order to extend the lifetime of the graphite components in HTGR, an important technical issue on graphite waste was extracted by investigating the method for disposing of graphite waste and an investigation of the technology for confirming integrity of the graphite components was carried out.

Oral presentation

Investigation of evaluation method for residual stress of graphite component of HTGR using micro-indentation method

Sumita, Junya; Shibata, Taiju; Tada, Tatsuya; Sawa, Kazuhiro

no journal, , 

It was shown that the relationship between indentation depth and residual stress based on experimental data obtained by changing the stress condition of graphite specimen parametrically.

Oral presentation

Development of evaluation method of degradation for graphite component in HTGR using non-destructive method

Tada, Tatsuya; Shibata, Taiju; Sumita, Junya; Sawa, Kazuhiro

no journal, , 

To develop non-destructive evaluation methods for oxidation damage on graphite components in High Temperature Gas-cooled Reactors (HTGRs), the applicability of ultrasonic wave and micro-indentation methods were investigated. As the results of investigation, the relationship between ultrasonic wave velocities and burn-off, oxidation weight loss of graphite, can be expressed empirically by exponential formulas and a wave propagation analysis with a wave-pore interaction model showed slightly less velocity reduction than experimental data of the oxidized graphite. Moreover, micro-indentation characteristics on the graphite samples were changed to show oxidation-induced degradation.

Oral presentation

Improvement of crystal packing of human MAP kinase JNK1 by point mutation for neutron crystallography

Nakaniwa, Tetsuko*; Fukata, Harumi*; Inoue, Tatsuya*; Kinoshita, Takayoshi*; Adachi, Motoyasu; Tamada, Taro; Kuroki, Ryota; Tada, Toshiji*

no journal, , 

JNK1 is a MAP kinase responsible for response of stress. JNK1 has 4 and 3 cysteine residues in embedded region and at molecular surface, respectively. Those cysteine residues would cause inactivation and aggregation of the molecule. Based of the analysis of packing in crystal of isozyme of JNK1, we found more salt bridge and hydrogen bonding interactions on the interface. In this study, we focus on the two cysteine residues and introduced modification into M3 mutant previously reported.

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