An equilibrium core depletion algorithm for pebble-bed reactors in the Griffin code

Schunert, Sebastian; Ortensi, Javier; Wang, Yaqi; Balestra, Paolo; Jaradat, Mustafa Mohammad; Calvin, Olin; Hanophy, Joshua; Harbour, Logan

doi:10.1016/j.anucene.2023.109980

Cited by 9 publications

(6 citation statements)

References 34 publications

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“…al. [28]. The existing direct equilibrium core capability provided the basis for the new running-in capability and so the purpose of this section it to review key points relevant to this report.…”

Section: Equilibrium Core Modeling In Griffinmentioning

confidence: 99%

“…The indices all have the same meaning as discussed in the previous paragraph and u is the flow velocity and a is the flow area. ∆τ l is the width of burnup bin l and ρl is the average pebble power density for burnup bin l. A simple upwind scheme is used to derive these discrete equations, as discussed in more detail in Reference [28]. Such a numerical scheme is known to have significant numerical diffusion, and its impact is explored further in Section 3.4.…”

Section: Equilibrium Core Modeling In Griffinmentioning

confidence: 99%

“…These equations state that the inflow to a streamline is a function of the outflow. Griffin includes logic to determine what fraction of pebbles leaving the core are recirculated to the top, with the remainder being made up with fresh pebble feed, based on user input as described in Reference [28]. In the case of the direct equilibrium core calculation, the functions in Equations 3 and 4 do not change in time, but as discussed in Section 4, timedependence is accounted for when specifying the dependence of inflow to the core on outflow for running-in simulations.…”

Section: Equilibrium Core Modeling In Griffinmentioning

confidence: 99%

“…Recently, Griffin has been used for analyzing pebble-bed reactors (PBRs) [3,7,22,24,28,29]. An overview of PBRs can be found in Reference [10] and general information about such reactors is not reviewed here, but some specific items related to two terms used frequently in this report, equilibrium core and running-in, are reviewed.…”

Section: Introductionmentioning

confidence: 99%

“…From this computed core configuration, various types of transient simulations can be initiated, including loss-of-forced-cooling (LOFC) accidents, reactivity insertion accidents (RIA), etc. The direct method implemented in Griffin for computing an equilibrium core is described in Reference [28] and reviewed in Section 1.1.…”

Section: Introductionmentioning

confidence: 99%

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Initial Demonstration of New Griffin Technologies for Simulating the Running-In Phase of Pebble Bed Reactors

Hanophy,

Park,

Labouré

et al. 2024

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Griffin is a reactor multiphysics modeling application based on MOOSE (Multiphysics Object-Oriented Simulation Environment) and specifically targeting transient modeling of advanced reactors. Griffin has been used recently to model pebble-bed reactors for the Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research and the Advanced Reactor Technology program. This modeling work has focused thus far on the direct calculation of equilibrium cores. This report documents an initial demonstration of a new running-in simulation capability. The new running-in capability is verified using the existing direct equilibrium core calculation capability. A simplified pebble-bed reactor model is then used to demonstrate the running-in simulation capability. This demonstration shows that Griffin is able to simulate years of operation during the running-in phase efficiently with each depletion step taking only several seconds. Two new technologies are also presented in this report which have been developed in Griffin that will be essential for improved accuracy both of the direct equilibrium core computation and the new running-in simulation capability. The first technology is an online cross section generation capability specifically targeted for pebble-bed reactors. This will improve the accuracy of the depletion calculation as the cross sections are generated at the exact core status. This also avoids the difficult step of pre-generating a separate standalone multigroup cross section set. Secondly, a newly implemented discretization for discontinuous finite element method (DFEM) S N transport in cylindrical (RZ) coordinates, which can be solved efficiently using the existing S N sweep solver, is discussed and some results are shown demonstrating the usefulness of the additional accuracy transport provides over a diffusion approximation.

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Section: Equilibrium Core Modeling In Griffinmentioning

confidence: 99%

Section: Equilibrium Core Modeling In Griffinmentioning

confidence: 99%

Section: Equilibrium Core Modeling In Griffinmentioning

confidence: 99%