Homogenized Viscoplastic Material Model for a Dual Cooled Lead Lithium Blanket

Sunday C. Aduloju; Timothy J. Truster; Paul W. Humrickhouse

doi:10.1109/TPS.2026.3665398

Homogenized Viscoplastic Material Model for a Dual Cooled Lead Lithium Blanket

Blanket and Fuel Cycle

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Abstract

A nonlinear multiphysics component scale finite element blanket model and homogenized viscoplastic material model are developed for modeling creep and void evolution in the dual cooled lead lithium (DCLL) blanket. The constitutive behavior of a material and the evolution of the voids within are highly coupled processes, which are governed by dissipative potential. The potential could be matched using homogenization approach and simplified representative volume to accurately capture the constitutive behavior of the blanket material system. The viscoplastic model is implemented within Multiphysics Object-Oriented Simulation Environment (MOOSE) and it is formulated based on the Gurson–Tvergaard–Needleman (GTN) method that is widely used for modeling damage evolution in ductile materials. A separate model that correlates changes in neutron damage and operational temperature to void swelling of F82H steel at fusion relevant temperatures is implemented to supply the volume fraction of the voids. The results of the homogenized strain and the stress-induced evolution of the cavities in the first wall (FW) and back wall (BW) are presented. The result of the creep analysis which is consistent with previous work showed that the maximum creep strain at the FW is about 0.45% at 3000 h with rupture time of about 42 000 h. The robust creep model capturing radiation and stress-induced voids evolution produced shorter time to onset of tertiary creep and rupture showing that the traditional creep model could be very conservative. The stress of 173 MPa at the FW would lead to larger stress-induced voids evolution compared with those induced by radiation.

Original language	English
Journal	IEEE Transactions on Plasma Science
DOIs	https://doi.org/10.1109/TPS.2026.3665398
State	Accepted/In press - 2026

Funding

Received 20 August 2025; revised 22 December 2025; accepted 2 February 2026. This work was supported by the Oak Ridge National Laboratory managed by University of Tennessee-Battelle Limited Liability Company for the U.S. Department of Energy (DOE) under contract number DEAC05-00OR22725. The review of this article was arranged by Senior Editor M. Kovari. (Corresponding author: Sunday C. Aduloju.) Sunday C. Aduloju and Paul W. Humrickhouse are with the Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830 USA (e-mail: [email protected]). ACKNOWLEDGMENT This work was supported by the Oak Ridge National Laboratory managed by University of Tennessee (UT)-Battelle, Limited Liability Company (LLC) for the U.S. Department of Energy (DOE) under contract number DEAC05-00OR22725. The U.S. government retains and the publisher, by accepting the paper for publication, acknowledges that the U.S. government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for U.S. government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-publicaccess-plan).

Keywords

Creep
F82H steel
Gurson–Tvergaard–Needleman (GTN) model
Multiphysics Object-Oriented Simulation Environment (MOOSE)
dual cooled lead lithium (DCLL) blanket
neutron irradiation
stress
voids

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10.1109/TPS.2026.3665398

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title = "Homogenized Viscoplastic Material Model for a Dual Cooled Lead Lithium Blanket",

abstract = "A nonlinear multiphysics component scale finite element blanket model and homogenized viscoplastic material model are developed for modeling creep and void evolution in the dual cooled lead lithium (DCLL) blanket. The constitutive behavior of a material and the evolution of the voids within are highly coupled processes, which are governed by dissipative potential. The potential could be matched using homogenization approach and simplified representative volume to accurately capture the constitutive behavior of the blanket material system. The viscoplastic model is implemented within Multiphysics Object-Oriented Simulation Environment (MOOSE) and it is formulated based on the Gurson–Tvergaard–Needleman (GTN) method that is widely used for modeling damage evolution in ductile materials. A separate model that correlates changes in neutron damage and operational temperature to void swelling of F82H steel at fusion relevant temperatures is implemented to supply the volume fraction of the voids. The results of the homogenized strain and the stress-induced evolution of the cavities in the first wall (FW) and back wall (BW) are presented. The result of the creep analysis which is consistent with previous work showed that the maximum creep strain at the FW is about 0.45\% at 3000 h with rupture time of about 42 000 h. The robust creep model capturing radiation and stress-induced voids evolution produced shorter time to onset of tertiary creep and rupture showing that the traditional creep model could be very conservative. The stress of 173 MPa at the FW would lead to larger stress-induced voids evolution compared with those induced by radiation.",

keywords = "Creep, F82H steel, Gurson–Tvergaard–Needleman (GTN) model, Multiphysics Object-Oriented Simulation Environment (MOOSE), dual cooled lead lithium (DCLL) blanket, neutron irradiation, stress, voids",

author = "Aduloju, \{Sunday C.\} and Truster, \{Timothy J.\} and Humrickhouse, \{Paul W.\}",

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year = "2026",

doi = "10.1109/TPS.2026.3665398",

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N2 - A nonlinear multiphysics component scale finite element blanket model and homogenized viscoplastic material model are developed for modeling creep and void evolution in the dual cooled lead lithium (DCLL) blanket. The constitutive behavior of a material and the evolution of the voids within are highly coupled processes, which are governed by dissipative potential. The potential could be matched using homogenization approach and simplified representative volume to accurately capture the constitutive behavior of the blanket material system. The viscoplastic model is implemented within Multiphysics Object-Oriented Simulation Environment (MOOSE) and it is formulated based on the Gurson–Tvergaard–Needleman (GTN) method that is widely used for modeling damage evolution in ductile materials. A separate model that correlates changes in neutron damage and operational temperature to void swelling of F82H steel at fusion relevant temperatures is implemented to supply the volume fraction of the voids. The results of the homogenized strain and the stress-induced evolution of the cavities in the first wall (FW) and back wall (BW) are presented. The result of the creep analysis which is consistent with previous work showed that the maximum creep strain at the FW is about 0.45% at 3000 h with rupture time of about 42 000 h. The robust creep model capturing radiation and stress-induced voids evolution produced shorter time to onset of tertiary creep and rupture showing that the traditional creep model could be very conservative. The stress of 173 MPa at the FW would lead to larger stress-induced voids evolution compared with those induced by radiation.

AB - A nonlinear multiphysics component scale finite element blanket model and homogenized viscoplastic material model are developed for modeling creep and void evolution in the dual cooled lead lithium (DCLL) blanket. The constitutive behavior of a material and the evolution of the voids within are highly coupled processes, which are governed by dissipative potential. The potential could be matched using homogenization approach and simplified representative volume to accurately capture the constitutive behavior of the blanket material system. The viscoplastic model is implemented within Multiphysics Object-Oriented Simulation Environment (MOOSE) and it is formulated based on the Gurson–Tvergaard–Needleman (GTN) method that is widely used for modeling damage evolution in ductile materials. A separate model that correlates changes in neutron damage and operational temperature to void swelling of F82H steel at fusion relevant temperatures is implemented to supply the volume fraction of the voids. The results of the homogenized strain and the stress-induced evolution of the cavities in the first wall (FW) and back wall (BW) are presented. The result of the creep analysis which is consistent with previous work showed that the maximum creep strain at the FW is about 0.45% at 3000 h with rupture time of about 42 000 h. The robust creep model capturing radiation and stress-induced voids evolution produced shorter time to onset of tertiary creep and rupture showing that the traditional creep model could be very conservative. The stress of 173 MPa at the FW would lead to larger stress-induced voids evolution compared with those induced by radiation.

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KW - dual cooled lead lithium (DCLL) blanket

KW - neutron irradiation

KW - stress

KW - voids

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JO - IEEE Transactions on Plasma Science

JF - IEEE Transactions on Plasma Science

ER -

Homogenized Viscoplastic Material Model for a Dual Cooled Lead Lithium Blanket

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