HIGH-FIDELITY EX-CORE CAPABILITIES IN VERA

Abstract

High-fidelity nuclear reactor calculations have become increasingly important when considering lifetime extensions of the current nuclear fleet. The need for performing large calculations has led to development of advanced, novel methods for faster and more efficient computing system use. Under the Consortium for Advanced Simulation of Light Water Reactors (CASL), we have enabled the capability to perform high-fidelity ex-core calculations in the Virtual Environment for Reactor Applications (VERA) by coupling with the Shift Monte Carlo (MC) radiation transport package. The codes are coupled inmemory, allowing for the pin-by-pin fission source from the core simulator to be used by Shift. This unique capability allows the user to obtain both in-core and ex-core quantities by running a single simulation. Examples of ex-core calculations that can be performed include multicycle vessel fluence, detector response during reactor start-up and operation, and coupon fluence. One main advantage of the VERA ex-core capability is its flexibility and ease of use; users can select default settings with the standard VERA input for typical calculations or create their own ex-core geometry for specific cases. Also, Shift takes advantage of hybrid deterministic-MC methods to reduce variance and computational time. This paper details the full suite of VERA ex-core capabilities and provides input examples, simulation results, and computing resource use suggestions. These new capabilities have the potential to impact a wide user group in the nuclear community by enhancing and enabling high-fidelity light water reactor (LWR) ex-core calculations.

Keywords

• ex-core
• casl
• hybrid methods