Abstract
In response to the nuclear industry desire to extend burnup beyond current licensing practices, the US Nuclear Regulatory Commission (NRC) released a research information letter (RIL) that provides a basis for analyzing fuel fragmentation, relocation, and dispersal (FFRD) in light-water reactors. Of the five elements discussed, the most ambiguous is the significance of transient fission gas (FG) release (FGR) (tFGR) and its effects on fuel performance under loss-of-coolant accident conditions. In fresh fuel, FG migration and eventual release is primarily governed by diffusion-based mechanisms at higher temperatures (>1,000 °C). However, the mechanisms governing FGR changes as burnup increases. More recent research indicates that FGR increases as burnup increases, specifically under temperature transient conditions, and this release occurs at lower temperatures with a new release mechanism. This behavior has been attributed to microcracking in the fuel and is likely related to microstructure embrittlement with the presence of over pressurized FG bubbles. The NRC RIL outlines the complexity of the phenomenon and a need for a deeper understanding to adequately address FFRD for regulatory application. Therefore, this manuscript intends to summarize the publicly available tFGR data and discuss the observed dependencies (e.g., burnup, heating rate, sample geometry, terminal temperature). An empirical model has been developed and benchmarked against recently published experimental data. However, this empirical model is limited to conditions for which fitting data exist and, therefore, a high-level discussion is included to provide a roadmap for atomistically-informed multiscale modeling in conjunction with experimental data collection to develop a mechanistic tFGR model widely applicable to a broad range of nuclear fuel conditions at high burnup.
| Original language | English |
|---|---|
| Article number | 154557 |
| Journal | Journal of Nuclear Materials |
| Volume | 584 |
| DOIs | |
| State | Published - Oct 2023 |
Funding
This manuscript is the result of a collaboration between the Nuclear Energy Advanced Modeling and Simulation (NEAMS) and the Advanced Fuels Campaign (AFC) of the US Department of Energy (DOE) Office of Nuclear Energy (NE), and the authors would like to express their sincere appreciation to the DOE NE programs and Chris Stanek (NEAMS national technical director) and Daniel Wachs (AFC national technical director) for championing the cross-program collaboration. Additionally, the authors world like to express their appreciation to Ian Greenquist and Tyler Gerczak for providing an in-depth technical review of this manuscript. Their feedback was critical to ensuring the technical content of the manuscript is of the highest quality. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05–00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US Government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).
| Funders | Funder number |
|---|---|
| Advanced Fuels Campaign | |
| Nuclear Energy Advanced Modeling and Simulation | |
| U.S. Department of Energy | |
| Office of Nuclear Energy |