Stress analysis of the TMSR graphite component under irradiation conditions

Yang, Xiong; Gao, Yantao; Yang, Zhong; Ding, Dong; Tsang, D.K.L.

doi:10.1007/s41365-018-0516-8

Cited by 8 publications

(3 citation statements)

References 15 publications

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“…The fast neutron flux in the HPA graphite decreases by an average of 3.07% per 1 cm length, while that in the RCA graphite decreases by average 5.54% per 1 cm length, 1.8 times larger than the former. The higher the neutron flux distribution gradient, the greater the plane maximum principal stress inside the graphite 30 . Therefore, the stress in the RCA graphite due to the irradiation flux gradient is higher than that in the HPA graphite at the same power.…”

Section: Results and Analysismentioning

confidence: 96%

A new structure design to extend graphite assembly lifespan in small modular molten salt reactors

et al. 2021

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Summary Dimensional change of the graphite assemblies due to irradiation is a key factor in limiting the service lifespan of the reactor core in small modular molten salt reactors. The graphite assembly structure, determining the fast neutron flux distribution and temperature distribution, has a notable impact on its dimensional change and hence its lifespan. In this article, we put forward an innovative solid hexagonal prism assembly (HPA) surrounded by fuel salt to prolong the lifespan of the graphite assemblies and compare it with the traditional hexagonal round channel assembly (RCA) with fuel salt flowing through its central round channel. Under the single‐cell model, the calculation results prove that the neutron flux distribution and temperature distribution in the HPA are more uniform than those in the RCA. The HPA deforms more slowly than the RCA under the same operating conditions. The lifespan of the RCA, defined as when it expands back to its original size, is 7.5 years under the 100 MW/m3 power density of fuel salt, while the lifespan of the proposed HPA is 8.4 years. The HPAs also allow a further expansion in the radial direction due to its noncontact arrangement in the core. It will take 14.9 years for the HPA assemblies to contact each other, which displays a significant improvement in lifespan.

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Section: Results and Analysismentioning

confidence: 96%

A new structure design to extend graphite assembly lifespan in small modular molten salt reactors

et al. 2021

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“…Creep in graphite helps to relieve stresses caused by temperature variations and dimensional shifts, ultimately preventing premature failures of graphite components [41]. The model that elucidates the correlation between irradiation neutron fluence, temperature, and graphite deformation is commonly referred to as the graphite material constitutive model [44,45]. The total strain within irradiated graphite ε total is the sum of five different strain components:…”

Section: Methodology 21 Constitutive Equations For Umatmentioning

confidence: 99%

Comparative Irradiated Dimensional Change Strain Analyses of Two Types of Graphite Components in a Thorium Molten Salt Reactor

Zhong,

Zou,

Wang

et al. 2024

Energies

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Nuclear graphite plays a crucial role in thermal-spectrum thorium molten salt reactors (TMSRs) as both the neutron moderator and the construct for the coolant flowing channel. When subjected to irradiation and elevated temperatures, graphite components experience considerable deformation due to a combination of dimensional changes, thermal expansion, irradiation creep, elastic deformation, and changes in thermomechanical characteristics. The lifespan of the graphite component is a limiting factor in TMSR designs as it strongly correlates with the dimensional changes of the graphite. To evaluate the thermal and mechanical reactions of graphite component under TMSR core conditions, it is necessary to couple models of thermal-hydraulics, neutronics, and thermal-mechanics. This paper presents an enhanced methodology for analyzing the deformation of graphite components using the finite element method. Then, this method was applied to analyze a 10-year deformation history of a hexagonal prism assembly (HPA) and it was compared with the traditional hexagonal round channel assembly (RCA). The results demonstrate that the stress–strain field of both types of graphite components undergo significant variations with the increasing neutron fluence from irradiation. HPA graphite exhibits a slower deformation as compared to RCA graphite when subjected to identical operating conditions. In this case, HPA graphite has a lifespan of approximately 10 years, while RCA graphite lasts only 8.8 years.

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“…However, in MSRs, as analyzed by Oak Ridge National Laboratory, 10‐13 the maximum stress in graphite component of molten salt breeder reactor (MSBR) during its expansion to the original dimension was only 700 psi, far lower than the tensile strength of about 5000 psi. Recently, Yang et al's work 14 shows that the maximum principal stresses in the MSR experiment (MSRE) components under different dose gradient assumptions are also lower than 1 MPa (~145 psi). Those results imply that crack or rupture by stress may not appear in graphite components of MSRs since its dose difference is usually <2.…”

Section: Introductionmentioning

confidence: 99%

Neutronic effect of graphite dimensional change in a small modular molten salt reactor

et al. 2020

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Summary Graphite is an excellent moderator widely used in fission nuclear reactors. However, the component dimensions and physical properties of graphite will be apparently affected by neutron radiation during the reactor operation. In molten salt reactors (MSRs), graphite dimensional change will not only cause the structural integrity issue, but also have obvious impacts on neutronic and thermal‐hydraulic behaviors due to the volume fraction (VF) change of fuel salt in the active core. Considering these effects synthetically, we have developed a multi‐physical coupling burnup code, including fuel management, neutron transportation, thermal‐hydraulic calculation, and dimensional change. Then we analyze the effects of graphite dimensional change in a small modular MSR (SM‐MSR). It can be concluded that the averaged shrink ratio of graphite in SM‐MSR is about 1.0% ΔL/L at the end of life while the lifespan of graphite can be more than 10 years with 66 MW/m3 power density. Although the dimensional change has a little effect on the neutronic properties, such as fuel burnup and temperature reactivity coefficients because of the limited change of averaged fuel salt VF from 10% to less than 12%, the local distributions, such as power density, temperature, mass flow, and fast neutron flux, have been affected by 10% to 30%, which cannot be neglected in practical engineering design. Finally, we have compared the fuel burnup and lifespan of graphite under different sizes of graphite components, and we recommend that the distance across flats of graphite block should be limited between 10 and 20 cm.

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Stress analysis of the TMSR graphite component under irradiation conditions

Cited by 8 publications

References 15 publications

A new structure design to extend graphite assembly lifespan in small modular molten salt reactors

A new structure design to extend graphite assembly lifespan in small modular molten salt reactors

Comparative Irradiated Dimensional Change Strain Analyses of Two Types of Graphite Components in a Thorium Molten Salt Reactor

Neutronic effect of graphite dimensional change in a small modular molten salt reactor

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