Effect of pulsed laser irradiation on the micro-plastic behavior of radiation shielding lead glasses

Wakui, Takashi; Yamasaki, Kazuhiko*; Futakawa, Masatoshi

Jikken Rikigaku, 22(2), p.96 - 104, 2022/06

https://doi.org/10.11395/jjsem.22.96

Pulsed laser irradiation and indentation tests on radiation shielding glasses and a lead-free glass were carried out. The size of irradiation damage of the glass with high lead content was larger than that with low content. The micro plastic behavior of glasses was quantitatively determined using the inverse analyses based on indentation results. Flow stress decreased with an increase of lead content and that in irradiated area was lower than that in unirradiated area. On the other hand, plastic flow resistance increased with an increase of the lead content and that in irradiated area was higher than that in unirradiated area. Fracture energy and critical size of plastic zone around tip of crack in unirradiated and irradiated areas were calculated based on experimental results including constants evaluated using the inverse analysis. These values decreased with an increase of the lead content and these values in irradiated area were lower than that in unirradiated area.

Development on laser cutting technique to suppress spatter particles aiming at disposal of radio-active waste

Naoe, Takashi; Teshigawara, Makoto; Futakawa, Masatoshi; Mizutani, Haruki; Muramatsu, Toshiharu; Yamada, Tomonori; Ushitsuka, Yuji*; Tanaka, Nobuatsu*; Yamasaki, Kazuhiko*

Proceedings of 8th International Congress on Laser Advanced Materials Processing (LAMP 2019) (Internet), 5 Pages, 2019/05

Laser cutting is one of the options in the disposal of radio-active waste, such as spallation neutron target vessel in J-PARC, etc. Due to unique characteristic of laser, such as non-contact system, it is more easily to provide remote-controlled system in comparison with conventional one, such as mechanical cutting machine, etc. However, a demerit of laser cutting is the sputter and fume caused by laser cutting, resulting in contamination with radio-active materials its surroundings. Recently it was developed that the spatter suppression technique by controlling laser beam profile in laser welding process. In order to apply this suppression technique to laser cutting, first of all, we attempted to observe the phenomenon at melting area during laser cutting using a high-speed video camera in order to make the physical model. The result showed that the appearance of fume and sputter were independently confirmed in the time evolution.

A Study on precipitation behavior of plutonium and other transuranium elements with N-cyclohexyl-2-pyrrolidone for development of a simple reprocessing process

Morita, Yasuji; Kawata, Yoshihisa*; Mineo, Hideaki; Koshino, Nobuyoshi*; Asanuma, Noriko*; Ikeda, Yasuhisa*; Yamasaki, Kazuhiko*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*; Kikuchi, Toshiaki*

Journal of Nuclear Science and Technology, 44(3), p.354 - 360, 2007/03

https://doi.org/10.3327/jnst.44.354

Precipitation behavior of Pu and other transuranium elements with N-cyclohexyl-2-pyrrolidone (NCP) has been examined to develop a simple reprocessing based only on precipitation method. From HNO solutions containing only Pu, both Pu(VI) and Pu(IV) were precipitated with NCP, but they required more NCP than in the U(VI) precipitation. Selective U(VI) precipitation from HNO solution containing U(VI) and Pu(IV) was achieved by stirring the solution for sufficient time after addition of NCP with ratio of [NCP]/[U]=1.4. Addition of an enough amount of NCP to U(VI)-Pu(VI) or U(VI)-Pu(IV) solutions gave a quantitative precipitation of both U and Pu. Neither Am(III) nor Np(V) was precipitated in the selective U precipitation and the simultaneous U-Pu precipitation. These results demonstrate the feasibility of the reprocessing by precipitation with NCP.

Development of a simple reprocessing process using selective precipitant for uranyl ions; Engineering studies for precipitating and separating systems

Yamasaki, Kazuhiko*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*; Kikuchi, Toshiaki*; Morita, Yasuji; Kawata, Yoshihisa*; Mineo, Hideaki; Koshino, Nobuyoshi*; Asanuma, Noriko*; Harada, Masayuki*; et al.

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 4 Pages, 2005/10

N-cyclohexyl-2-pyrrolidone (NCP), can selectively precipitate U(VI) ions in aqueous nitric acid solutions. Utilizing this property, we have been developing a simple reprocessing process of spent nuclear fuel based only on precipitation method. In the first precipitation step, only U is separated by precipitation in a yield of about 70%, and in the second precipitation step both U and Pu are recovered and separated from fission products (FP) and other transuranium elements (TRU). In the present study, a precipitator and a precipitate separator were designed and built up, and were tested with aspets of operationability and system performance.

The Nuclear-Fuel Manufacturing Adaptability Study of UNH Crystal-Conversion Products

Yamasaki, Kazuhiko*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*; Kikuchi, Toshiaki*

JNC TJ8420 2004-002, 48 Pages, 2003/12

JNC-TJ8420-2004-002.pdf:1.33MB

Crystallization procedure is considered to have an adaptability to new reprocessing process based on the PUREX process because it has an advantage in recovering rather pure uranium from contaminated uranium solution without reagent. Hydrated uranyl nitrate (UNH) crystal from crystallization procedure is fed to the conversion process into UO2 for the fabrication of nuclear fuel. We have researched for denitration or conversion methods which is suited to UNH crystal and molten salt since. Due to the selection from some denitration or conversion methods, it is very important to research. an adaptability of the product from the denitration or conversion methods.In this study, we investigated some powder properties of the products, as important factors for nuclear -fuel-manufacturing, from the denitration or conversion methods. Next, we selected pelletizing process, viblo-packing fuel process and covered-particle fuel process as major manufacturing-process of nuclear fuel and research the conditions of uranyl oxide required from each processes. From the comparison between these conditions and the result from denitration or conversion methods, we estimated an adaptability of these methods to nuclear -fuel-manufacturing. As a result, we showed that freeze dry method, ADU and AUC method may be suited to pelletizing process. We also showed that electric reduction method, internal gelation method, and external gelation method may be suited to viblo-packing and covered-particle fuel process.

The Study to wash UNH crystals in the reprocessing process

Yamasaki, Kazuhiko*; *; Tamaki, Yoshihisa*

JNC TJ8400 2003-016, 40 Pages, 2003/02

JNC-TJ8400-2003-016.pdf:0.9MB

Crystallization procedure is considered to have an adaptability to new reprocessing process based on the PUREX process because it has an advantage in recovering rather pure uranium from contaminated uranium solution without any reagents. Up to now, a small-scale uranium test has been performed to confirm an applicability of crystallization. We focus on the decontamination factor (DF) of FP in the crystallization procedure. Some mock experiments have been also performed and suggested that most of FP is on the surface of crystals in mother liquor. We expected that the content of the mother liquor decreases with increasing of the size of crystals. Consequently it is possible that the DF increases with increasing of the size of crystals. In this study, we performed the experiment to estimate the DF of Ce (ⅵ) of various size of UNH crystals. And our expectation is confirmed.

None

Yamasaki, Kazuhiko*; *; Tamaki, Yoshihisa*

JNC TJ8420 2002-004, 87 Pages, 2002/02

JNC-TJ8420-2002-004.pdf:1.84MB

no abstracts in English

A Method of fabrication meso-nozzle for bubbling

Osone, Ryuji; Bucheeri, A.; Kurishita, Hiroaki*; Kato, Masahiro*; Yamasaki, Kazuhiko*; Maekawa, Katsuhiro*; Naoe, Takashi; Futakawa, Masatoshi

no journal, , 

Liquid mercury target system for high power spallation neutron sources is being developed. When high intensity proton beams are injected into the target, pressure waves are generated by the thermal shock in mercury and pitting damage will be imposed on the target vessel. Bubble injection into mercury is effective to mitigate the pressure waves. In this work, we propose a method of fabricating meso-nozzle for bubble injection. The method is based on powder metallurgy by inserting thin glass fibers into a metal powder matrix to create a green compact, followed by sintering at a temperature between the melting points of the powder and the fiber. SUS316L and molybdenum powders were used as the nozzle matrix materials. In order to investigate optimum sintering condition, experiments were performed at different combination of pressing load and sintering temperature. We found that in molybdenum high relative density and straight hole with circlar cross section were obtained.

Material properties degradation of radiation shielding lead glasses by laser irradiation

Wakui, Takashi; Yamasaki, Kazuhiko*; Futakawa, Masatoshi

no journal, , 

Pulsed Nd:YAG laser was irradiated to two radiation shielding glasses with the different lead content and a lead-free glass. Although no irradiation damage of the lead-free glass was visually confirmed in the laser irradiation condition of this study, the irradiation damage in the lead glasses could be recognized and the lead glass with the high lead content tends to cause the higher irradiation damage. Vickers hardness, elastic modulus and fracture toughness were evaluated by indentation technique with a Vickers indenter were 82-75%, 90-80% and 71-65% of the lead-free glass, respectively. The yield stresses evaluated by the inverse analysis using Kalman's filter based on load-depth curve obtained by the indentation technique with a spherical indenter were 87-67% of the lead-free glass. The yield stress of the irradiation damage area of the lead glass with the low lead content decreased to 74% of unirradiated area.