Abstract
The default energy deposition model in the CASL neutronics code MPACT assumes all fission energy is deposited locally in fuel rods. Furthermore, equilibrium delayed energy release is assumed for both steady-state and transient calculations. These approximations limit the accurate representation of the heat generation distribution in space and its variations over time, which are essential for power distribution and thermal-hydraulic coupling calculations. In this paper, an improved energy deposition model is presented in both the spatial and time domains. Spatially, the energy deposition through fission, neutron capture, and slowing-down reactions are explicitly modeled to account for the heat generation from all regions of a reactor core, and a gamma smearing scheme is developed that utilizes the gamma sources from neutron fission and capture. In the time domain, the delayed energy release is modeled by solving an additional equation of delayed heat emitters, similar to the equation of delayed neutron precursors. To allow the explicit heat generation coupling, the interfaces between MPACT and CTF were updated to transfer separate heat sources for different material regions (fuel, clad, moderator and guide tube). The results show that the distributions of the energy deposition between MPACT and MCNP agree very well for various 2-D assembly and quarter-core problems without TH feedback. The MPACT/CTF coupled calculation for the hot full power quarter-core case exhibited a reduced peak pin power by 2.3% and a reduced peak fuel centerline temperature by 17 K when using the explicit energy deposition and heat transfer. The new model also shows a maximum 100 pcm keff effect on assembly depletion problems and an increased overall energy release by 7% in a PWR reactivity-initiated accident (RIA) problem.
| Original language | English |
|---|---|
| Title of host publication | International Conference on Physics of Reactors |
| Subtitle of host publication | Transition to a Scalable Nuclear Future, PHYSOR 2020 |
| Editors | Marat Margulis, Partrick Blaise |
| Publisher | EDP Sciences - Web of Conferences |
| Pages | 378-385 |
| Number of pages | 8 |
| ISBN (Electronic) | 9781713827245 |
| DOIs | |
| State | Published - 2020 |
| Event | 2020 International Conference on Physics of Reactors: Transition to a Scalable Nuclear Future, PHYSOR 2020 - Cambridge, United Kingdom Duration: Mar 28 2020 → Apr 2 2020 |
Publication series
| Name | International Conference on Physics of Reactors: Transition to a Scalable Nuclear Future, PHYSOR 2020 |
|---|---|
| Volume | 2020-March |
Conference
| Conference | 2020 International Conference on Physics of Reactors: Transition to a Scalable Nuclear Future, PHYSOR 2020 |
|---|---|
| Country/Territory | United Kingdom |
| City | Cambridge |
| Period | 03/28/20 → 04/2/20 |
Funding
This research was supported by the Consortium for Advanced Simulation of Light Water Reactors (http://www.casl.gov), an Energy Innovation Hub (http://www.energy.gov/hubs) for Modeling and Simulation of Nuclear Reactors under US Department of Energy Contract No. DE-AC05-00OR22725. This research also made use of the resources of the High Performance Computing Center at Idaho National Laboratory, which is supported by the Office of Nuclear Energy of the US Department of Energy and the Nuclear Science User Facilities under Contract No. DE-AC07-05ID14517.
Keywords
- Delayed energy
- Explicit energy deposition
- Gamma smearing
- MPACT