Final Project Report on RCCS Testing with Air-based NSTF

Lisowski, Darius; Gerardi, C.; Kilsdonk, D. J.; Bremer, Nathan; Lomperski, S.; Hu, Rui; Kraus, Adam; Bucknor, Matthew; Lv, Qiuping; Lee, Taeseung; Farmer, M. T.

doi:10.2172/1350591

Cited by 15 publications

(10 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The HTGRs appeal to the nuclear industry due to their inherent safety features, high thermal-to-electric conversion efficiency, and the ability to provide high-temperature process heat (Wang et al (2021)). Many HTGR designs rely on the Reactor Cavity Cooling System (RCCS) for passive decay heat removal and safe reactor shutdown during accident scenarios due to its relatively simple design, the reliance on natural forces, and the potential for high levels of performance (Lisowski et al (2016)). The RCCS is designed to ensure that the vessel wall and the fuel peak temperature are maintained at safe limits during normal operation and accident scenarios, to maintain the reactor cavity concrete and support structures at safe limits, to sustain the intended function and performance across the 40-year life span of a reactor installation, and to accomplish the above functions without human intervention or active systems (Lisowski et al (2016)).…”

Section: Introductionmentioning

confidence: 99%

FY22 Progress on Computational Modeling of the Water-Based NSTF

Ooi¹,

Lv²,

Hu³

et al. 2022

Self Cite

View full text Add to dashboard Cite

This report summarizes the system-level modeling effort by Argonne National Laboratory (Argonne) of the Natural convection Shutdown heat removal Test Facility (NSTF) in FY22. As an extension of the effort from FY21, this year's work focuses primarily on the two-phase modeling of the NSTF using RELAP5-3D, particularly with the inclusion of the cavity model.The results from simulations were used to compare against experimental data for benchmarking purposes of the RELAP5 deck. Additionally, RELAP5 was used as a predictive tool to guide planned test operations and identify expected system behaviors. In the first part of this report, details are provided of the cavity omitted model where heat flux is applied directly as a boundary condition to the risers. The general trend predicted by the RELAP5 model matches that from the experimental data when a single-phase natural circulation flow is first established, followed by an oscillatory two-phase period and finally a stable two-phase flow. However, the onset of oscillations is predicted early by the model due to the smaller thermal mixing region in the tank. However, by expanding the simulated thermal mixing region in the tank, the onset of oscillations predicted by the model is able to match that from the experiment. These oscillations where studied in depth and are deduced to be flashing-induced instability.The model was then modified to simulate an accident scenario case where a representative heat load based on the full-scale Framatome's 625 MW t SC-HTGR was applied directly to the riser channels. The simulated initial and boundary conditions were identical to those performed experimentally, facilitating direct comparisions between the predicted and experimental results. It was determined that the results showed some discrepancies remain, likely due to the overprediction of vapor generation rate by the computer model.In the second part of this report, the cavity model is re-introduced where it is observed that the RELAP5 prediction is now able to capture the major trends of the observed flow commonly observed during two-phase conditions. However, the onset of oscillations is once again predicted early by the model, possibly caused by the underprediction of heat loss from the heater and cavity. This is likely due to the omission of support structures in the cavity that can act as additional pathways for heat to escape to the environment. To overcome the underprediction of heat loss, part of the insulation surrounding the cavity side panels and the back of the heaters are removed to allow heat to escape directly to the environment, which then improves the RELAP5 prediction.Parametric studies are also performed to investigate the effects of heater power, tank inventory ii ANL-ART-257FY22 Progress on Computational Modeling of the Water-Based NSTF September 2022 level, and tank gas space pressure on flow behaviors, also in direct comparison to conditions tested experimentally. User option-61 in the RELAP5-3D input deck, which changes the heat transfer coefficient correla...

show abstract

Section: Introductionmentioning

confidence: 99%

FY22 Progress on Computational Modeling of the Water-Based NSTF

Ooi¹,

Lv²,

Hu³

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…For HTGRs, there are mainly two RCCS designs as shown in Figure 5 which as currently under discussion: an air-cooled system initially proposed by GA [24] and an active, cold (<30°C), constant water flow system proposed by AREVA [25]. The Natural Convection Shutdown Heat Removal Test Facility (NSTF) at Argonne National Laboratory has conducted both air-based and water-based RCCS experiments since 2016 [26,27] to support the DOE vision of aiding U.S. vendors in designing future reactor concepts, advancing the maturity of codes for licensing, and ultimately developing safe and reliable reactor technologies.…”

Section: Reactor Cavity Cooling Systemmentioning

confidence: 99%

High-Temperature Gas-Cooled Reactor Research Survey and Overview: Preliminary Data Platform Construction for the Nuclear Energy University Program

Qin

Minseop

Vietz

et al. 2022

View full text Add to dashboard Cite

Since the U.S. Department of Energy Office of Nuclear Energy initiated the Nuclear Energy University Program (NEUP) in 2009, there are 29 NEUP projects focusing on high-temperature gas-cooled reactor (HTGR) research up to July 2022. The resultant research product, either experimental or computational, were published as final NEUP reports, journal articles and conference proceedings. However, these federally funded products have been scattered and sometimes cannot be easily accessed.To improve access to this valuable HTGR validation data and optimize the return on the significant investment made by the Department of Energy, the Advanced Reactor Technologies (ART) Gas-Cooled Reactor (GCR) program started a survey of completed and ongoing HTGR NEUP projects to develop a public-access database specific for HTGRs applications that can be used to retrieve computational fluid dynamics and system code validation data. This effort will help guide future NEUP-funded research, define new state of the ART Phenomena Identification and Ranking Table (PIRT), and promote the usage of this data in the codes validation matrices. This report provides an overview of the NEUP-funded HTGR-related research projects from Fiscal Year (FY) 2009-2021 and identifies validation knowledge gaps still existing in HTGR thermal-fluid research.A preliminary data platform has been developed for the 29 NEUP projects investigating HTGR thermal hydraulics, including their final reports as well as the available scientific publications. As an ultimate goal for this work, the ART-GCR program will create a central database at Idaho National Laboratory to identify, organize, and store these datasets generated by experimental investigations or computational models, experimental facility descriptions, and publicly-available academic products from the HTGR-related NEUP projects and provide future guidance for the storage and transmission of important project documentations for later NEUP projects as well.

show abstract

“…Further work is required to better capture the stored energy within a fuel pebble when using the 2-D porous medium model. The Natural convection Shutdown heat removal Test Facility (NSTF) is a large-scale thermal-hydraulics test facility built at Argonne National Laboratory to study the performance of passive safety systems for advanced nuclear reactors [12]. It was designed to provide highquality experiment data for validating the performance of Reactor Cavity Cooling System (RCCS) concepts for decay heat removal in advanced nuclear reactors.…”

Section: Coupled 2-d/1-d Primary System Modeling Demonstrationmentioning

confidence: 99%

“…12 shows the transient outlet cooling water temperature and the heat flux output to cooling water in the null-transient simulation.…”

mentioning

confidence: 99%

Development of a Reference Model for Molten-Salt-Cooled Pebble-Bed Reactor Using SAM

O’Grady

Zou

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

Final Project Report on RCCS Testing with Air-based NSTF

Abstract: Impact of 33% break initiated at t=57.6min. Average riser ∆T saw a 7.4 • C rise . . . 191 Impact of 33% break initiated at t=57.6min. Average riser heat flux saw a -9.33%

Cited by 15 publications

References 4 publications

FY22 Progress on Computational Modeling of the Water-Based NSTF

FY22 Progress on Computational Modeling of the Water-Based NSTF

High-Temperature Gas-Cooled Reactor Research Survey and Overview: Preliminary Data Platform Construction for the Nuclear Energy University Program

Development of a Reference Model for Molten-Salt-Cooled Pebble-Bed Reactor Using SAM

Contact Info

Product

Resources

About