## A parallel multi-domain solution methodology applied to nonlinear thermal transport problems in nuclear fuel pins

## Abstract

We describe an efficient and nonlinearly consistent parallel solution methodology for solving coupled nonlinear thermal transport problems that occur in nuclear reactor applications over hundreds of individual 3D physical subdomains. Efficiency is obtained by leveraging knowledge of the physical domains, the physics on individual domains, and the couplings between them for preconditioning within a Jacobian Free Newton Krylov method. Details of the computational infrastructure that enabled this work, namely the open source Advanced Multi-Physics (AMP) package developed by the authors are described. The details of verification and validation experiments, and parallel performance analysis in weak and strong scaling studies demonstrating the achieved efficiency of the algorithm are presented. Moreover, numerical experiments demonstrate that the preconditioner developed is independent of the number of fuel subdomains in a fuel rod, which is particularly important when simulating different types of fuel rods. Finally, we demonstrate the power of the coupling methodology by considering problems with couplings between surface and volume physics and coupling of nonlinear thermal transport in fuel rods to an external radiation transport code.

- Authors:

- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

- Publication Date:

- Research Org.:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)

- Sponsoring Org.:
- USDOE Office of Science (SC)

- OSTI Identifier:
- 1185622

- Alternate Identifier(s):
- OSTI ID: 1247048

- Grant/Contract Number:
- AC05-00OR22725

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Journal of Computational Physics

- Additional Journal Information:
- Journal Volume: 286; Journal Issue: C; Journal ID: ISSN 0021-9991

- Publisher:
- Elsevier

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; Inexact Newton; Jacobian free Newton Krylov; Krylov subspace method; Domain decomposition; Preconditioning; Iterative method; Parallel algorithm

### Citation Formats

```
Philip, Bobby, Berrill, Mark A., Allu, Srikanth, Hamilton, Steven P., Sampath, Rahul S., Clarno, Kevin T., and Dilts, Gary A. A parallel multi-domain solution methodology applied to nonlinear thermal transport problems in nuclear fuel pins. United States: N. p., 2015.
Web. doi:10.1016/j.jcp.2015.01.029.
```

```
Philip, Bobby, Berrill, Mark A., Allu, Srikanth, Hamilton, Steven P., Sampath, Rahul S., Clarno, Kevin T., & Dilts, Gary A. A parallel multi-domain solution methodology applied to nonlinear thermal transport problems in nuclear fuel pins. United States. doi:10.1016/j.jcp.2015.01.029.
```

```
Philip, Bobby, Berrill, Mark A., Allu, Srikanth, Hamilton, Steven P., Sampath, Rahul S., Clarno, Kevin T., and Dilts, Gary A. Mon .
"A parallel multi-domain solution methodology applied to nonlinear thermal transport problems in nuclear fuel pins". United States. doi:10.1016/j.jcp.2015.01.029. https://www.osti.gov/servlets/purl/1185622.
```

```
@article{osti_1185622,
```

title = {A parallel multi-domain solution methodology applied to nonlinear thermal transport problems in nuclear fuel pins},

author = {Philip, Bobby and Berrill, Mark A. and Allu, Srikanth and Hamilton, Steven P. and Sampath, Rahul S. and Clarno, Kevin T. and Dilts, Gary A.},

abstractNote = {We describe an efficient and nonlinearly consistent parallel solution methodology for solving coupled nonlinear thermal transport problems that occur in nuclear reactor applications over hundreds of individual 3D physical subdomains. Efficiency is obtained by leveraging knowledge of the physical domains, the physics on individual domains, and the couplings between them for preconditioning within a Jacobian Free Newton Krylov method. Details of the computational infrastructure that enabled this work, namely the open source Advanced Multi-Physics (AMP) package developed by the authors are described. The details of verification and validation experiments, and parallel performance analysis in weak and strong scaling studies demonstrating the achieved efficiency of the algorithm are presented. Moreover, numerical experiments demonstrate that the preconditioner developed is independent of the number of fuel subdomains in a fuel rod, which is particularly important when simulating different types of fuel rods. Finally, we demonstrate the power of the coupling methodology by considering problems with couplings between surface and volume physics and coupling of nonlinear thermal transport in fuel rods to an external radiation transport code.},

doi = {10.1016/j.jcp.2015.01.029},

journal = {Journal of Computational Physics},

number = C,

volume = 286,

place = {United States},

year = {2015},

month = {1}

}

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