Regulatory Technology Development Plan - Sodium Fast Reactor: Mechanistic Source Term – Trial Calculation

Mechanistic source term development for liquid fueled MSRs - Model Development Update

“…As mentioned above, the development of the MSR MST assessment capability discussed in this report builds on the successful MST evaluation of the sodium fast reactor (SFR) concept developed as part of the DOE Advanced Reactor Technology, Regulatory Technology Development Plan (Grabaskas et al, 2015, Grabaskas et al, 2016aand Grabaskas et al, 2016b. The general methodology for MSR MST is summarized in Figure 1.…”

“…The range of reactor technologies in this initial set of advanced, non-LWR designs indicates the need for a generic source term approach that can address specific aspects of individual designs. A mechanistic source term approach was recently demonstrated for a generic metal fueled sodium fast reactor concept (Grabaskas et al, 2016a) that can inform future advanced reactor source term developments. The major challenges for developing an MST approach for non-LWR advanced reactor designs will likely be the need for new modeling tools, alteration modifications of existing codes, and an extensive experimental program to obtain necessary thermochemical and thermophysical data (Jerden et al, 2019a).…”

“…The main factors that can influence chemical speciation in an MSR include total concentrations, fuel salt chemical composition, fuel salt redox potential, temperature, pressure, and reaction kinetics. Grabaskas et al (2016a) recently developed a model to calculate the speciation of key fission products for sodium fast reactor MST analyses using a thermochemical database and the modeling software HSC chemistry. Specifically, the chemical speciation and phase distribution was calculated at equilibrium by using the Gibbs free energy minimization method, which requires knowing the enthalpy and entropy of formation and the heat capacity for each possible species that may form.…”

“…Thermodynamic modeling will not represent the physical transport processes described above and other modeling tools will be needed to fully account for the transport of radionuclides. As part of MST analyses for the sodium fast reactor, for example, the bubble transport processes were quantified with the IFR bubble code developed at Argonne (Grabaskas et al, 2016a). Although bubble formation mechanisms will be different in MSRs, bubbles are expected to be a pathway to transport entrained radionuclides during normal operations or an accident scenario.…”

“…In addition, source term analyses can play a key role in reactor siting and the development of emergency planning zones and reactor site boundaries [NRC 1993, NRC 2003, NRC 2005. For new generation advanced reactor concepts, source term analyses can provide valuable feedback into the design process and facilitate risk-informed engineering decisions (e.g., Yoshioka et al, 2012, Grabaskas et al, 2016a.…”