Carrying-out of whole nuclear fuel materials in Plutonium Research Building No.1

Inagawa, Jun; Kitatsuji, Yoshihiro; Otobe, Haruyoshi; Nakada, Masami; Takano, Masahide; Akie, Hiroshi; Shimizu, Osamu; Komuro, Michiyasu; Oura, Hirofumi*; Nagai, Isao*; et al.

JAEA-Technology 2021-001, 144 Pages, 2021/08

JAEA-Technology-2021-001.pdf:12.98MB

Plutonium Research Building No.1 (Pu1) was qualified as a facility to decommission, and preparatory operations for decommission were worked by the research groups users and the facility managers of Pu1. The operation of transportation of whole nuclear materials in Pu1 to Back-end Cycle Key Element Research Facility (BECKY) completed at Dec. 2020. In the operation included evaluation of criticality safety for changing permission of the license for use nuclear fuel materials in BECKY, cask of the transportation, the registration request of the cask at the institute, the test transportation, formulation of plan for whole nuclear materials transportation, and the main transportation. This report circumstantially shows all of those process to help prospective decommission.

Solvent extraction of cesium using DtBuDB18C6 into various organic solvents

Sasaki, Yuji; Morita, Keisuke; Kitatsuji, Yoshihiro; Ito, Keisuke*; Yoshizuka, Kazuharu*

Solvent Extraction Research and Development, Japan, 28(2), p.121 - 131, 2021/00

https://doi.org/10.15261/serdj.28.121

High concentration of Cs is present in high-level radioactive waste. It is well-known that Cs is an alkali element and difficult to extract completely into an organic phase. Crown ether compounds are widely available for Cs extractants; DtBuDB18C6 (di--butyl-dibenzo-18crown6), was used in this study. Organic solvents used for the industrial applications, such as -dodecane and 1-octanol, have low solubility concerning the compound; other solvents were employed and tested. In this study, ketone-, ether-, and ester-type solvents showed high solubility for DtBuDB18C6 and DtBuDB18C6, when dissolved in ketones and alcohols, exhibited relatively high Cs distribution ratios ((Cs)), closely to 10.

Study on loss-of-cooling and loss-of-coolant accidents in spent fuel pool, 6; Analysis on oxidation behavior of fuel cladding tubes by the SAMPSON code

Morita, Yoshihiro*; Suzuki, Hiroaki*; Naito, Masanori*; Nemoto, Yoshiyuki; Kaji, Yoshiyuki

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 9 Pages, 2019/05

In this study, the SAMPSON code was modified to evaluate severe accidents in a spent fuel pool (SFP). Not only the SFP but also upper spaces of the SFP, walls of the reactor building, and the blowout panel were included. Air oxidation models obtained by the Zircaroy-4 cladding (ANL model) and the Zircaroy-2 cladding (JAEA model) were included in the modified SAMPSON code. Experiments done by Sandia National Laboratory using simulated fuel assemblies equivalent to those of an actual BWR plant were analyzed by the modified SAMPSON code to confirm the functions for analysis of the severe SFP accidents.

Determination of fusion barrier distributions from quasielastic scattering cross sections towards superheavy nuclei synthesis

Tanaka, Taiki*; Narikiyo, Yoshihiro*; Morita, Kosuke*; Fujita, Kunihiro*; Kaji, Daiya*; Morimoto, Koji*; Yamaki, Sayaka*; Wakabayashi, Yasuo*; Tanaka, Kengo*; Takeyama, Mirei*; et al.

Journal of the Physical Society of Japan, 87(1), p.014201_1 - 014201_9, 2018/01

https://doi.org/10.7566/JPSJ.87.014201

Excitation functions of quasielastic scattering cross sections for the Ca + Pb, Ti + Pb, and Ca + Cm reactions were successfully measured by using the gas-filled recoil-ion separator GARIS. Fusion barrier distributions were extracted from these data, and compared with the coupled-channels calculations. It was found that the peak energies of the barrier distributions for the Ca + Pb and Ti + Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the Ca + Cm is located slightly below the 4n evaporation ones. This results provide us helpful information to predict the optimum beam energy to synthesize superheavy nuclei.

Observation of the laser-induced surface dynamics using the single-shot soft X-ray laser probe

Hasegawa, Noboru; Ochi, Yoshihiro; Kawachi, Tetsuya; Nishikino, Masaharu; Ishino, Masahiko; Imazono, Takashi; Kaihori, Takeshi; Morita, Toshimasa; Sasaki, Akira; Terakawa, Kota*; et al.

X-Ray Lasers 2012; Springer Proceedings in Physics, Vol.147, p.117 - 120, 2014/00

https://doi.org/10.1007/978-3-319-00696-3_19

We have developed the femto-second laser pump and soft X-ray laser probe system in order to observe the dynamical processes of the femto-second laser ablation. By using this system, we succeed to obtain the temporal evolution of the soft X-ray reflectivity from the laser induced Pt surface. The results lead that the rate of decrease in the reflectivity of the probe beam has a non-linear relation with the pump laser fluence.

Novel soft-hard donor ligand, NTAamide, for mutual separation of trivalent actinides and lanthanides

Sasaki, Yuji; Tsubata, Yasuhiro; Kitatsuji, Yoshihiro; Morita, Yasuji

Chemistry Letters, 42(1), p.91 - 92, 2013/01

https://doi.org/10.1246/cl.2013.91

The new N-donor extractant, NTAamide, is synthesized and tested for extraction and separation of Am-Cm-Ln. It was found that the high separation factors for An-Ln can be seen at 0.1-0.2M HNO, which suggest the de-protonation to N donor is important to show the high SF between An and Ln. From the present work, the stable N-donor extractant having high SF of An-Ln from nitric acid to n-dodecane can be obtained. The highest separation factor, 6.5, of Am-Cm for the condition of 0.5M NTAamide (C8) in n-dodecane and 10 mM TEDGA in 0.2M HNO as one of the highest SF values is found. NTAamide is the promising extractants for partitioning process of Am-Cm-Ln.

Actinides extractability trends for multidentate diamides and phosphine oxides

Sasaki, Yuji; Kitatsuji, Yoshihiro; Sugo, Yumi; Tsubata, Yasuhiro; Kimura, Takaumi; Morita, Yasuji

Solvent Extraction Research and Development, Japan, 19, p.51 - 61, 2012/00

http://www.solventextraction.gr.jp/serdj/jurnalpdf/vol19/pp51-61.pdf

Diamides and phosphine oxides having many kinds of the central frames were synthesized and employed in order to see the behavior of actinides(An)(III), (IV), (V) and (VI). Diamides synthesized here have two, three, or four donor atoms of amidic and etheric oxygen (nitrogen or sulfur, instead) atoms in their central frames, namely the extractants can work as bi-, tri-, and tetradentate modes. Di-phosphine di-oxides ((Bis(diphenylphosphoryl)methane (BDPPM) and bis(diphenylphosphoryl)ethylene (BDPPE)), carbamoylmethylphosphine oxide (octylphenyl-,-diisobutyl-carbamoylmethylphosphine oxide (CMPO)) are used as the representative actinide extractants. Metal ions of Eu(III), Th(IV), U(VI), Np(V), Pu(IV) and Am(III) in perchloric acid were extracted into nitrobenzene or n-dodecane. Measurement of value at the different extractant concentration gives the information on extraction reaction and their extraction ability. From the present work, the best extractant is BDPPM, due to the strong affinity concerning P=O and form of the bidentate mode with six-membered ring chelation. However, this extractant have low solubility in -dodecane. Taking the applicatory properties, e.g., high solubility in -dodecane, easy organic synthesis, gasification by combustion and high actinide extractability, into consideration, diglycolamide (DGA) is a promising extractant for radioactive waste treatment.

Separation of Am, Cm and Ln by combination of two novel-diamide compounds at -dodecane and HNO system

Sasaki, Yuji; Kitatsuji, Yoshihiro; Tsubata, Yasuhiro; Sugo, Yumi; Shirasu, Noriko; Morita, Yasuji

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 5 Pages, 2011/12

Mutual separation of Am, Cm and lanthanides (Ln) is important to develop the partitioning process of high-level radioactive waste, although this method is difficult to establish due to their very similar chemical behavior, same oxidation state (III) and similar ionic radii. Relative high separation values for these metals can be seen when the multidentate ligands, e.g., diethylene-triamine-N,N,N',N'',N''-pentaacetic acid (DTPA), and softN-donor extractants are employed. We examine to use the combination of two-multidentate ligands having N atoms in their structures in behalf of the high separation of Am, Cm and Ln. Various diamide-type ligands can be synthesized from the initial materials of carboxylic acid and amine, and the aimed materials can be tailored to have high solubility in either HNO orn-dodecane, in case short or long alkyl chains are attached in amidic Natoms. Taking the simultaneous use of these materials into consideration, hydrophilic and lipophilic diamide compounds with different complexing ability for trivalent Ln and actinide (An) are used into both of the aqueous and the organic phases in order to enlarge their separation factors. This technique is applicable in the salt-free system and diamide can be gasificated by combustion, which reduces the secondary-radioactive waste. Two diamide compounds, DGA (diglycolamide) and DOODA (dioxaoctanediamide) as the representative multidentate ligands, have the different features for Ln-complexation, namely DGA has higher D values for middle-Ln than those of light-Ln, and DOODA shows the opposite trend to DGA. TDdDGA (N,N,N',N'-tetradodecyl-diglycolamide) and DOODA(C2) (N,N,N',N'-tetraethyl-dioxaoctanediamide) have high solubility in n-dodecane and HNO, respectively, and the condition of 0.1 M TDdDGA in n-dodecane and 0.5 MDOODA(C2) in 3 M HNO gives the separation factors of La/Gd: 1128 and Am/Cm:3.26.

Separation of Am, Cm and lanthanides by solvent extraction with hydrophilic and lipophilic organic ligands

Sasaki, Yuji; Kitatsuji, Yoshihiro; Tsubata, Yasuhiro; Sugo, Yumi; Morita, Yasuji

Solvent Extraction Research and Development, Japan, 18, p.93 - 101, 2011/00

http://www.solventextraction.gr.jp/serdj/jurnalpdf/vol18/pp93-101.pdf

The mutual separation of Am, Cm and lanthanides (Ln) by the hydrophilic and lipophilic ligands present in both aqueous and organic phases were studied. The hydrophilic ligands used here are DTPA, malonamide, amicacid, TEDGA and DOODA (C2) and four kinds of extractants, TODGA, TDdDGA, DOODA (C8) and DOODA (C12). DOODA can extract light lanthanides with higher D values into the organic phase, on the other hand DGA shows strong complexing ability with middle and heavy lanthanides in the aqueous phase. The high separation factor, over 1000, of La and Gd can be seen in the extraction using extractant, TDdDGA, and DOODA(C2) as the masking agent. The separation factors of Am/Cm by DOODA(C8, C12) and DGA alone extractants are 1.51-1.94, the values with over 3 can be attained by the proposed conditions in this work.

Detection and activity of iodine-131 in brown algae collected in the Japanese coastal areas

Morita, Takami*; Niwa, Kentaro*; Fujimoto, Ken*; Kasai, Hiromi*; Yamada, Haruya*; Nishiuchi, Ko*; Sakamoto, Tatsuya*; Godo, Waichiro*; Taino, Seiya*; Hayashi, Yoshihiro*; et al.

Science of the Total Environment, 408(16), p.3443 - 3447, 2010/06

https://doi.org/10.1016/j.scitotenv.2010.04.001

Iodine-131 (I) was detected in brown algae collected off the Japanese coast. The maximum measured specific activity of I in brown algae was 0.370.010 Bq/kg-wet. Cesium-137 (Cs) was also detected in all brown algal samples used in this study. There was no correlation between specific activities of I and Cs in these seaweeds. Low specific activity and minimal variability of Cs in brown algae indicated that past nuclear weapon tests were the source of Cs. Although nuclear power facilities are known to be pollution sources of I, there was no relationship between the sites where I was detected and the locations of nuclear power facilities. Most of the sites where I was detected were near big cities with large populations. On the basis of the results, we suggest that the likely pollution source of I, detected in brown seaweeds, is not nuclear power facilities, but nuclear medicine procedures.