Nowadays Small Modular Reactors (SMRs) adopting passive mitigation strategies are the most promising nuclear technology for the next deployment of power generation. Deterministic safety analyses have a key role for designing the mitigation strategies and for a safety review process. These analyses are carried-out with best-estimate thermal-hydraulic system codes. Different SMRs designs are currently under development and are, in general, characterized by some common features with the current reactors and by other features typical of their designs. Therefore, though numerous previous numerical Natural Circulation (NC) studies, further analyses are necessary to characterize the capability of codes against available experimental data representative of SMR phenomenology. Though different scaling methods have been developed, considering the complex geometry of a NPP and the presence of two-phase flow, it is not possible to avoid distortions in the design of experimental facilities. Even though the distortions should be limited to not dominants phenomena, scaled-down facilities are characterized by scaling-up limitations that affect the capability of the code to predict full-scale behavior. Therefore, in a V&V process, the uncertainty related to the code scaling-up capability is still an open issue and should be addressed. Based on previous activities, having as a reference the NC DOE tests developed in the OSU-MASLWR facility, the USNRC TRACE code has been validated for simulating NC in steady and transient conditions. Since the OSU-MASLWR is volume and height scaled, the target of this paper is to assess the scaling-up capability of the OSU-MASLWR Reactor Pressure Vessel nodalization against NC phenomenology typical of SMR, having as a base the OSU-MASLWR-002 single phase NC data. This, also, give some first insights about the TRACE scaling-up capability against single-phase NC in integral type configuration.
Scaling-Up Capabilities of TRACE Integral Reactor Nodalization against Natural Circulation Phenomena in Small Modular Reactors
D’Auria Francesco
Ultimo
Conceptualization
2022-01-01
Abstract
Nowadays Small Modular Reactors (SMRs) adopting passive mitigation strategies are the most promising nuclear technology for the next deployment of power generation. Deterministic safety analyses have a key role for designing the mitigation strategies and for a safety review process. These analyses are carried-out with best-estimate thermal-hydraulic system codes. Different SMRs designs are currently under development and are, in general, characterized by some common features with the current reactors and by other features typical of their designs. Therefore, though numerous previous numerical Natural Circulation (NC) studies, further analyses are necessary to characterize the capability of codes against available experimental data representative of SMR phenomenology. Though different scaling methods have been developed, considering the complex geometry of a NPP and the presence of two-phase flow, it is not possible to avoid distortions in the design of experimental facilities. Even though the distortions should be limited to not dominants phenomena, scaled-down facilities are characterized by scaling-up limitations that affect the capability of the code to predict full-scale behavior. Therefore, in a V&V process, the uncertainty related to the code scaling-up capability is still an open issue and should be addressed. Based on previous activities, having as a reference the NC DOE tests developed in the OSU-MASLWR facility, the USNRC TRACE code has been validated for simulating NC in steady and transient conditions. Since the OSU-MASLWR is volume and height scaled, the target of this paper is to assess the scaling-up capability of the OSU-MASLWR Reactor Pressure Vessel nodalization against NC phenomenology typical of SMR, having as a base the OSU-MASLWR-002 single phase NC data. This, also, give some first insights about the TRACE scaling-up capability against single-phase NC in integral type configuration.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
