Hello, A new project on the LCRC cluster has been requested. Please forward the information on to the LCRC Allocation sub-committee. Applicant's name: Rui Hu Applicant's institution: ANL Applicant's division: NE Project Name: SHARP-IF Project title: SHARP – Intermediate Fidelity Modeling Associated funding: DOE-Nuclear Energy Other Systems: Science: An intermediate fidelity (IF) modeling method is being pursued under NEAMS Reactor IPSC (SHARP) for a fast-running, modest-fidelity, whole-core transient analyses capability. The approach is essential for design scoping and engineering analyses and could lead to improvements in the design of the new generations of reactors and to the reduction of uncertainties in safety analysis. In FY11, a three-dimensional momentum source model was developed to model the anisotropic flow in the wire-wrapped rod bundle without the need to resolve the geometric details. The momentum source model was examined in both 7-pin and 37-pin configurations using the commercial CFD code STAR-CCM+ for steady-state ABTR operating conditions. (This new modeling strategy could be considered as a coarse-mesh CFD approach.) Also, the system analysis code SAS and the commercial CFD code STAR-CCM+ are being incorporated into the SHARP framework for a multi-scale analysis of Sodium Fast Reactors. In the previous fiscal year, the feasibility of performing coupled SAS/STAR-CD simulations of protected loss-of-flow accident was demonstrated. In that effort, the outlet plenum was modeled by STAR-CD and the rest of the primary coolant system and the secondary system were simulated by SAS, and the flow and temperature conditions at the interface were exchanged between the two codes as boundary conditions. In the planned activities for FY12, the above two developments will be integrated. The wire-wrapped pin-bundles will be simulated by a CFD code in a transient for the first time, while the rest of the primary loop and the secondary loop will be modeled by the system code. The momentum source model will be implemented and the effects of this modeling strategy will be examined in selected transients. With this approach and with moderate computing resource, the high-fidelity CFD tool can be used to resolve the important flow and temperature distributions throughout the reactor core or plant while still maintaining the whole-plant safety analysis capabilities of a systems analysis code. If the validity is confirmed, a fast-running, modest-fidelity, whole-core transient analyses capability is then demonstrated. Project description: In this project, the system analysis code SAS will be coupled with the CFD code, STAR-CCM+ to demonstrate a fast-running, modest-fidelity, whole-core transient analysis. The application of the CFD code for a long-time transient in a nuclear reactor is still very demanding for computing resource. A 100s transient STAR-CCM+ simulation of a 50 million cells pin bundle model could cost 128,000 core-hours. In this project, this computation burden will be relieved through a coarser mesh approach for the wire-wrapped pin bundle, in which the detailed wire geometry will not be modeled (a bare bundle configuration will be used instead) and a momentum source model will be introduced to account for its effect on introducing swirling cross flow. Access to the Fusion cluster will enable us to examine the validity of this approach for reactor safety analysis. STAR-CCM+ employs the finite volume formulation of the Reynolds-Averaged Navier-Stokes method to determine the detailed 3D velocity and temperature field in the reactor fuel assembly. In SAS, coolant thermal-hydraulics is simulated with a one-dimensional (axial) fashion. However, SAS also include the neutronic, mechanical, and fuel performance models to simulate the integrated response of the reactor core, the reactor primary and secondary coolant loops, the reactor control and protection systems, and the balance-of-plant to accidents caused by loss of coolant flow, loss of heat rejection, or reactivity insertion. Both codes are available in Argonne and routinely used in various modeling and simulation activities. STAR-CCM+ has already been installed and used in Fusion, while SAS is an in-house Fortran code and can be complied in Fusion. At Argonne, the CFD codes STAR-CD and STAR-CCM+ are routinely applied to simulations that use 8-200 cores, and good parallel performance has been observed. As problem size increases, i.e. for finer meshes and for large pin bundles, larger numbers of cores would be utilized and based on data from the developers good parallel performance will continue to be expected. On the other hand, SAS is a fast running system analysis code, and its computation burden is generally insignificant in the coupled SAS/STAR simulations. All jobs run on Fusion will be run in parallel. A typical large case may cost 8 cores/node * 25 nodes * 240 hours of run time = 48000 core-hours. Project URL: Requested allocation: 480000 Q1: 80000 Q2: 150000 Q3: 100000 Q4: 150000 Justification: The requester has used undetermined amount hours of their initial startup project. In addition to approving an initial amount, please specify a Category and Subcategory for this project. For a list of the current selection of approved categories, please see: https://wiki.lcrc.anl.gov/wiki/Processes/Categories Once the Allocation committee has approved the project, please go to the Project Management page to create it: https://accounts.lcrc.anl.gov/projects.php Thank You, The LCRC Accounts System