Transition toward thorium fuel cycle in a molten salt reactor by using plutonium

Cui, De-Yang; Xia, Siyou; Li, X.X.; Xiang-Zhou, Cai; Chen, Jingen

doi:10.1007/s41365-017-0303-y

Cited by 29 publications

(3 citation statements)

References 22 publications

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“…The burnup calculation in this paper adopts the Molten Salt Reactor Refueling and Reprocessing System analysis code (MSR-RRS) [24] developed based on SCALE6.1 [25]. MSR-RRS has been validated in detail and widely used since its development, proving that the MSR-RRS is reliable for molten salt reactor burnup calculation [26,27]. In the burnup calculation, k eff is maintained constant by online feeding makeup salt.…”

Section: Models and Methodsmentioning

confidence: 99%

Comparative Study on the Neutronic Performance of Thermal and Fast Molten Salt Reactors under Once-Through Fuel Cycle

Zhu

Liu

et al. 2023

International Journal of Energy Research

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Once-through molten salt reactors have the advantages of easy availability of fuel, nuclear nonproliferation, and low technical difficulty. It is expected to be the earliest commercial molten salt reactor fuel cycle mode. The current research on the neutronic performance of the once-through fuel cycle mainly focuses on the thermal spectrum range, and broader spectrum research needs to be carried out further. In particular, the fuel utilization characteristics of molten salt fast reactors in once-through fuel cycle are not yet clear. In addition, small modular design is one of the trends of molten salt reactor development, and small modular design under thermal and fast spectrum has different advantages and needs further comparative analysis. In this paper, the single lattice, bare reactor, and core with reflector models are used to compare the neutronic performance in once-through fuel cycle from thermal to fast spectrum, which includes burnup, variation of fuel salt composition and volume with burnup, temperature reactivity coefficient, neutron irradiation lifetime, and small modular size. The results show that the burnup increases first, then decreases, and then increases again with the increase of the average lethargy causing fission (EALF). For small-scale molten salt reactors, the difference in fuel utilization under thermal and fast spectra is small. However, for large-scale reactors, the burnup under fast spectrum is significantly higher than that under thermal spectrum. When the EALF is large enough, and the neutron loss ratio is small enough, the breed-and-burn (BNB) fuel cycle mode can be realized, and then, the fuel utilization will be significantly improved. In the fast spectrum reactors, the HN and volume of molten salt change violently because of the longer burnup period. Based on the infinite single lattice model, the temperature reactivity coefficient increases first, then decreases, and increases again with EALF. It is negative over the entire energy spectrum. In addition, the small modular designs are discussed by the bare reactor model, and the neutron irradiation lifetime of the materials is analyzed by the core model with a reflector.

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Section: Models and Methodsmentioning

confidence: 99%

Comparative Study on the Neutronic Performance of Thermal and Fast Molten Salt Reactors under Once-Through Fuel Cycle

Zhu

Liu

et al. 2023

International Journal of Energy Research

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“…In actinide series, plutonium (Pu) attracts extensive interesting in nuclear industry such as nuclear weapon and nuclear reactor fuels mainly due to its excellent nuclear properties [1, 2]. Metallurgically, elemental plutonium crystallizes into six stable radioactive allotropes, that is, α, β, γ, δ, δ′, and ε phases at the room temperature and its melting point (about 912 K) [3, 4].…”

Section: Introductionmentioning

confidence: 99%

Site‐dependent correlation strength and occupation number of 5f electrons in alpha phase plutonium metal

Lü

Xin

et al. 2023

Int J of Quantum Chemistry

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In order to quantify the site‐dependent correlation strengths in terms of the quasi‐particle weights and the occupation numbers of 5f electrons in alpha phase plutonium metal with eight crystallographically nonequivalent atomic sites Pun (n = 1–8), we perform a first principles calculation by using a many‐body method merging density functional theory with dynamical mean‐field theory plus the relativistic and correlation effects. The quasi‐particle weight, the electronic spectrum function, the hybridization function, as well as the occupation number of Pu 5f electrons all suggest that Pu1 and Pu8 atoms have the most itinerant and the most localized 5f electrons, respectively, while the other atoms Pun (n = 2–7) exhibit an intermediate correlation strength. The quasi‐particle weights demonstrate that only the jj or intermediate coupling scheme is more appropriate for Pu 5f electrons in comparison with the Russel–Saunders (LS) scheme. The electronic spectrum function and the occupation analysis establish that Pu 5f electrons simultaneously have dual itinerant and localized regimes with average 5f occupation numbers of n5f between 4.8994 and 4.9628, which are mainly composed of 5f4, 5f5, and 5f6 configurations, irrespective of different atomic sites. Finally, we also estimate the so‐called quasi‐particle band structure to directly compare with angle‐resolved photoemission spectrum.

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“…The thorium‐uranium fuel cycle is considered as a potential self‐sustaining/breeding fuel without using fast neutron reactors since the reproduction factor of neutrons (represented as η ) of the “fissile” nuclei 233 U is greater than 2.0 over a wide range of thermal neutron spectrum 1‐3 . It offers attractive features such as low‐level radioactive waste and less transuranic (TRU) elements production, since thorium needs to absorb more neutrons to form highly radiotoxic TRU compared to uranium.…”

Section: Introductionmentioning

confidence: 99%

Ex‐core transition to thorium cycle in a small modular heavy‐water moderated molten salt reactor with unchanged concentration of heavy metal nuclides in the fuel salt

Zhang

Chen

et al. 2021

Int J Energy Res

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Summary Ex‐core transition to thorium fuel cycle is an effective way to address the issue of the lacking of the 233U in nature. It consists to extract online the thorium bred 233Pa from the core and store it outside. The obtained 233Pa stockpile will decay into the 233U (T1/2 = 27 days), and when enough 233U is cumulated, a new 233U‐based reactor can be loaded. However, this approach will inevitably provoke the heavy nuclides (HN) concentration in the core during the extraction operation, which would affect the chemical stability of fuel salt and subsequently endanger the safety of the core operation. In this study, an improved ex‐core transition with unchanged HN concentration is proposed for a 500‐MWth small modular heavy‐water moderated molten salt reactor (SM‐HWMSR). To achieve this, two operating stages are needed. In the first stage, transuranic (TRU) from the spent fuel of LWRs is used to feed the low enrichment uranium (LEU, 19.75 wt% 235U/U) started core with 300 operating days to ensure negative temperature reactivity coefficient (TRC). In the second stage, the thorium bred 233U from the first stage is mixed with TRU to refuel the core. The proposed ex‐core transition scheme aims to burn TRU, meanwhile breed 233U to start new MSRs. The fuel cycle performance over 60‐years' operation is analyzed. The results demonstrate that it is possible to realize ex‐core transition with unchanged concentration of HN in the fuel salt. As the fraction of 233U in the mixed fuel is set to be 15 mol%, it only takes 3 years to start a new reactor with the stored 233U. The radiotoxicity of TRU‐based fuel is decreased after 60 years' burning in the SM‐HWMSR core. Novelty Statement “Ex‐core transition to thorium cycle in an SM‐HWMSR with unchanged concentration of heavy metal nuclides in the fuel salt” was investigated by Yapeng Zhang, Jianhui Wu, Jingen Chen, and Xiangzhou Cai. The results demonstrate that it is possible to realize ex‐core transition with unchanged concentration of HN in the fuel salt. As the fraction of 233U in the mixed fuel is set to be 15 mol%, it only takes 3 years to start a new reactor by the stored 233U.

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Transition toward thorium fuel cycle in a molten salt reactor by using plutonium

Cited by 29 publications

References 22 publications

Comparative Study on the Neutronic Performance of Thermal and Fast Molten Salt Reactors under Once-Through Fuel Cycle

Comparative Study on the Neutronic Performance of Thermal and Fast Molten Salt Reactors under Once-Through Fuel Cycle

Site‐dependent correlation strength and occupation number of 5f electrons in alpha phase plutonium metal

Ex‐core transition to thorium cycle in a small modular heavy‐water moderated molten salt reactor with unchanged concentration of heavy metal nuclides in the fuel salt

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