Griffin Open Xe-100 Model and Results

Contact: Ryan Stewart, [email protected]

Model link: Open Xe-100 Model

Griffin Open Xe-100 Model

This model is a 200 MW pebble bed reactor developed using Griffin (Wang et al., 2025); it uses a 2D axisymmetric representation of the reactor core. This model is discussed in detail in Stewart et. al. (Stewart et al., 2022). The instantaneous core power density shown in Figure 1 can differentiate the regions of the core, where the darkest blue regions are part of the reflector and fuel chute and the red-to-blue gradient represents the fuel region and cavity. For a more detailed explanation of the geometry of the model, see Stewart et al. (Stewart et al., 2022).

Instantaneous core power density of the Open Xe-100 Reactor at steady state.

Figure 1: Instantaneous core power density of the Open Xe-100 Reactor at steady state.

Griffin solves the neutron transport problem using the diffusion equation approximation. For transient problems, Griffin can use methods like point reactor kinetics (PRKs) or the improved quasi-static (IQS) method. Griffin supports homogenization equivalence with Superhomogenization (SPH) factors, which this model uses.

For this model, there are four input files: (1) a steady-state eigenvalue calculation, (2) a null transient using IQS, (3) a transient using IQS, and (4) a transient using point kinetics equations (PKE)s. The output for the steady-state problem includes a number of binary files. The IQS runs are dependent on these output binaries for their initial conditions. The PKE run is dependent on PKE parameters generated by the IQS transient. Therefore, the inputs should be run in the order they have been listed in.

The input files for each simulation are described in the following:

Griffin Open Xe-100 steady-state

Griffin Open Xe-100 null transient

Griffin Open Xe-100 IQS transient

Griffin Open Xe-100 PKE transient

The results for these models are presented in the following:

Griffin Open Xe-100 results

Running the Regression Tests

Griffin uses the MOOSE test runner to run regression tests. Tests are stored in the tests file in the open-xe100 directory along with the input files.

Navigate so that open-xe100 is your present working directory and run:



griffin-opt --run tests

This will execute each input file and compare the output to the values in the gold directory.

References

  1. R. Stewart, P. Balestra, D. Reger, and E. Merzari. Generation of localized reactor point kinetics parameters using coupled neutronic and thermal fluid models for pebble-bed reactor transient analysis. Annals of Nuclear Energy, 174:109143, 2022. URL: https://www.sciencedirect.com/science/article/pii/S0306454922001785#s0065, doi:https://doi.org/10.1016/j.anucene.2022.109143.[BibTeX]
  2. Yaqi Wang, Zachary M. Prince, Hansol Park, Olin W. Calvin, Namjae Choi, Yeon Sang Jung, Sebastian Schunert, Shikhar Kumar, Joshua T. Hanophy, Vincent M. Labouré, Changho Lee, Javier Ortensi, Logan H. Harbour, and Jackson R. Harter. Griffin: a moose-based reactor physics application for multiphysics simulation of advanced nuclear reactors. Annals of Nuclear Energy, 211:110917, 2025. URL: https://www.sciencedirect.com/science/article/pii/S0306454924005802, doi:https://doi.org/10.1016/j.anucene.2024.110917.[BibTeX]