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Nakayama, Shinsuke; Furutachi, Naoya; Iwamoto, Osamu; Watanabe, Yukinobu*
NEA/NSC/R(2020)4 (Internet), p.345 - 349, 2022/10
Long-lived fission products (LLFPs) generated in nuclear reactors are strongly desired to be converted to stable or short-lived nuclides. Recently, it has been considered to transmute LLFPs by spallation reactions with high energy particles, and some experimental studies revealed that spallation reaction cross-sections induced by deuteron are larger than proton-induced ones. These results suggest the possibility that nuclear transmutation of LLFPs using deuteron beams is more efficient than one using proton beams. On the other hand, we have been developing a code system dedicated for deuteron-induced reactions, called DEURACS. DEURACS has been originally developed to contribute to the design of deuteron accelerator neutron sources. In the present study, we apply DEURACS to calculation of deuteron-induced spallation reactions on LLFPs. Through comparison with measured data, the applicability of DEURACS will be discussed.
Kunieda, Satoshi; Furutachi, Naoya*; Minato, Futoshi; Iwamoto, Nobuyuki; Iwamoto, Osamu
NEA/NSC/R(2020)4 (Internet), p.329 - 331, 2022/10
A new nuclear data library, ImPACT/LLFP-2018, is developed for an innovative study on the transmutation of long-lived fission products. In this work, we estimated cross-sections based on a nuclear model code CCONE, reflecting new knowledge on the nuclear structure theory and cross-section measurement. For instance, we used microscopic nuclear model to improve a phenomenological level density model. The pre-equilibrium model parameters are also optimized based on new experimental data of RIKEN/RIBF. Present library stores neutron and proton-induced cross-sections up to 200 MeV for 160 stable/unstable nuclei covering the long-lived fission products such as 
Se, 
Zr, 
Pd and 
Cs. Through a comparison with available experimental data on the stable isotopes, it is found that the present data gives predictions of cross-sections better than those from JENDL-4.0/HE, TENDL-2017 and the INCL model.
Sugawara, Takanori; Katano, Ryota; Tsujimoto, Kazufumi
no journal, ,
This study aims to investigate the impact of impurities in the transmutation cycle on the accelerator-driven system (ADS) neutronics design. For the uranium from the partitioning, the accompaniment of 20 wt.% U against the Pu weight is acceptable although the MA transmutation amount will be decreased slightly. For the rare earth (RE) from the partitioning, the accompaniment of 5 wt.% RE against the MA weight is allowable. In the reprocessing, the decontamination factor, DF=10 for RE is enough from the viewpoint of the neutronics design. Through these investigations, the required conditions for the impurities in the partitioning, the MA fuel fabrication and the reprocessing processes were clarified from the viewpoint of the ADS neutronics design.
Motokawa, Ryuhei
no journal, ,
Sano, Yuichi; Kawanobe, Kazunori*; Sakamoto, Atsushi; Kofuji, Hirohide; Takeuchi, Masayuki; Suzuki, Hideya; Matsumura, Tatsuro
no journal, ,
Japan Atomic Energy Agency (JAEA) has developed several new extractants which are significantly effective in trivalent minor actinides (MA(III)) recovery from high acidic media such as high level liquid waste (HLLW). In order to design an efficient MA(III) recovery process using these new extractants, it is important to obtain their kinetic data as well as equilibrium ones in the solvent extraction system. In this study, mass transfer coefficients of trivalent lanthanides (Ln(III)), which are surrogates of MA(III), between HNO
solution and tetra dodecyl diglycol amide (TDdDGA) or hexa octyl nitrilo triacetic amide (HONTA) / n-dodecane solvent were evaluated by the single drop technique and Nitsch cell tests. The mass transfer coefficients of Ln(III) back-extraction in HNO / TDdDGA system were relatively smaller than those in the extraction step, but they could be improved by the addition of 2-ethyl-1-hexanol into the TDdDGA / n-dodecane solvent. The mass transfer of Ln(III) between HNO solution and HONTA/n-dodecane solvent was considerably slower than that between HNO solution and TDdDGA / n-dodecane solvent. Based on the mass transfer coefficients obtained in these evaluations, process conditions for MA(III) recovery using mixer-settlers and centrifugal contactors were discussed.
Toigawa, Tomohiro; Tsubata, Yasuhiro; Matsumura, Tatsuro
no journal, ,
Radiation energy transfer to extraction solvent in minor actinide separation process were simulated by using a Particle and Heavy Ion Transport code System (PHITS). PHITS enabled to calculate the absorbed dose to extraction solvent in situations of intricately shaped apparatus or oil-water mixed state because the code were based on Monte-Carlo algorithm. It was found that the absorbed dose value from 
-ray depended on the size of the apparatus, while that from alpha-ray was depended on the droplet size in oil-water mixed state. It was demonstrated the degradation yields of the extractant could be evaluated by reference to the experimentally obtained G-values.