Study on method to achieve high transmutation of LLFP using fast reactor

Wakabayashi, Toshio; Tachi, Yoshiaki; Takahashi, Makoto; Chiba, Satoshi; Takaki, Naoyuki

doi:10.1038/s41598-019-55489-w

Cited by 17 publications

(11 citation statements)

References 27 publications

(12 reference statements)

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“…As shown in Fig. 1 (c), 169 pins in the form of mixed ZnSe 41,42 and YD2 were arranged in the assembly 30,31 . As shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In this case, 135 Cs and 93 Zr, both with small neutron absorption cross sections were placed in the radial blanket region, and 129 I and 99 Tc, both with large neutron absorption cross sections were placed in the shield region and axial blanket away from the fuel region Therefore, the transmutation rate of all nuclides was less than 0.5%/y. On the other hand, a study on a method designed to achieve a high transmutation rate (about 8%/y) for four nuclides ( 79 Se, 99 Tc, 107 Pd, 129 I) was conducted 30 . Based on these studies, a system that further improves the transmutation efficiency of the six nuclides was explored.…”

Section: Introductionmentioning

confidence: 99%

“…Here, the support ratio (SR) was defined as the ratio of the amount of each nuclide transmuted by the fast breeder reactor to the amount of each nuclide (MA and LLFP) produced by the fast breeder reactor 28,30,31 .…”

Section: Introductionmentioning

confidence: 99%

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Concept of a Fast Breeder Reactor To Transmute MA and LLFP

Wakabayashi

2021

Preprint

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The long-term issues of nuclear power systems are the effective use of uranium resources and the reduction of radioactive waste. Important radioactive wastes are minor actinides (MA: 237 Np, 241 Am, 243 Am, etc.) and long-lived fission products (LLFP: 129 I, 99 Tc, 79 Se, etc.). The purpose of this study was to show a system that can simultaneously achieve the breeding of fissile materials and the transmutation of MA and LLFP in one fast reactor. Transmutation was carried out by loading innovative Duplex type MA fuel in the core region and LLFP containing moderator in the first layer of the radial blanket. Breeding was achieved in the core and axial blanket. As a result, it was clarified that in this fast breeder reactor, a breeding ratio of about 1.1 was obtained, and MA and LLFP achieved a support ratio of 1 or more. The transmutation rate was 10.3%/y for 237 Np, 14.1%/y for 241 Am, 9.9%/y for 243 Am, 1.6%/y for 129 I, 0.75%/y for 99 Tc, and 4%/y for 79 Se. By simultaneously breeding fissile materials and transmuting MA and LLFP in one fast reactor, it will be possible to solve the long-term issues of the nuclear power reactor system, such as securing nuclear fuel resources and reducing radioactive waste.

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“…As shown in Fig. 1 (c), 169 pins in the form of mixed ZnSe 41,42 and YD2 were arranged in the assembly 30,31 . As shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Concept of a Fast Breeder Reactor To Transmute MA and LLFP

Wakabayashi

2021

Preprint

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“…Selenium is a metalloid element having a melting point of 221 °C and should be in a liquid phase at the operating temperature (expected to be about 600 °C) of the ANES. Therefore, ZnSe, which has a melting point of 1526 °C and a thermal conductivity of 19.04 W/(m∙K) 41 , 42 , was selected as a compound form that would be a solid phase when loaded into the system. Zirconium, Technetium and Palladium are transition metals with melting points of 1852 ℃, 2157 ℃ and 1554 ℃, respectively.…”

Section: Methodsmentioning

confidence: 99%

Transmutation of long-lived fission products in an advanced nuclear energy system

Sun

Luo

Lan

et al. 2022

Sci Rep

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Disposal of long-lived fission products (LLFPs) produced in reactors has been paid a lot attention for sustainable and clean nuclear energy. Although a few transmutation means have been proposed to address this issue, there are still scientific and/or engineering challenges to achieve efficient transmutation of LLFPs. In this study, we propose a novel concept of advanced nuclear energy system (ANES) for transmuting LLFPs efficiently without isotopic separation. The ANES comprises intense photoneutron source (PNS) and subcritical reactor, which consist of lead–bismuth (Pb-Bi) layer, beryllium (Be) layer, and fuel, LLFPs and shield assemblies. The PNS is produced by bombarding radioactive cesium and iodine target with a laser-Compton scattering (LCS) γ-ray beam. We investigate the effect of the ANES system layout on transmutation efficiency by Monte Carlo simulations. It is found that a proper combination of the Pb-Bi layer and the Be layer can increase the utilization efficiency of the PNS by a factor of ~ 10, which helps to decrease by almost the same factor the LCS γ-beam intensity required for driving the ANES. Supposing that the ANES operates over 20 years at a normal thermal power of 500 MWt, five LLFPs including 99Tc, 129I, 107Pd, 137Cs and 79Se could be transmuted by more than 30%. Their effective half-lives thus decrease drastically from ~ 106 to less than 102 years. It is suggested that this successful implementation of the ANES paves the avenue towards practical transmutation of LLFPs without isotopic separation.

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“…4,6 Furthermore, the chemical compound and manufacturing of I-129 have been previously investigated. 12 The investigation concluded that BaI 2 (density of 5.15 g/cm 3 ) is the suitable chemical compound for this particular LLFP from the point of view of chemical stability and easy manufacturing. As for the Tc-99, the metallic form of Tc with a density of 11.5 g/cm 3 is selected.…”

Section: Introductionmentioning

confidence: 97%

Performance indices optimization of l ong‐lived fission products transmutation in fast reactors

Liem

Tahara

Takaki

et al. 2021

Intl J of Energy Research

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Summary An investigation on the nuclear transmutations of elemental long‐lived fission products (LLFPs) in a fast reactor is being conducted in Japan, focusing on the Se‐79, Zr‐93, Tc‐99, Pd‐107, I‐129, and Cs‐135, to reduce the environmental burden. With their high neutron flux and adequate excessive neutrons, fast reactors are considered strong candidates for transmuting those LLFPs into stable isotopes or shorter effective half‐lives under the partition and transmutation (P/T) strategy. In this investigation, the LLFP subassembly is assumed to be loaded into the radial blanket region of a Japanese MONJU class sodium‐cooled fast reactor (710 MWth). This work focuses on two LLFPs, namely, I‐129 and Tc‐99. The LLFPs are mixed with YD2 or YH2 moderator material to enhance the LLFP transmutation rate. The results include the optimal position of the LLFP assembly in the radial blanket and the optimal moderator volume fraction to optimize the transmutation performance indices, that is, the transmutation rate (TR, %/year), the support factor (SF is defined as the ratio of transmuted to produced LLFP), and the effective half‐life (T‐half) of the LLFPs. A countermeasure is also devised to resolve the expected higher power peak at the fuel assembly adjacent to the LLFP assembly. The neutronics and burnup analyses are conducted using the continuous‐energy Monte Carlo SERPENT2 code with the JENDL‐4.0 nuclear data library.

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Study on method to achieve high transmutation of LLFP using fast reactor

Cited by 17 publications

References 27 publications

Concept of a Fast Breeder Reactor To Transmute MA and LLFP

Concept of a Fast Breeder Reactor To Transmute MA and LLFP

Transmutation of long-lived fission products in an advanced nuclear energy system

Performance indices optimization of l ong‐lived fission products transmutation in fast reactors

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