Development of a mechanistic source term approach for liquid-fueled Molten Salt Reactors

Abstract

In addition to the significant progress being made in accident analyses for some molten salt reactor (MSR) concepts, there remains a need for a thorough, step-by-step source term analyses that includes parametric sensitivity analyses and trial calculations. This report provides a basis for developing an MSR source term model by examining the successful methodology used in the sodium fast reactor (SFR) mechanistic source term work presented by Grabaskas et al., [2016a]. Useful risk analyses tools currently in use for developing MSR source term analyses are also summarized, such as those developed for the European Safety Assessment of the Molten Salt Fast Reactor (SAMOFAR) project. Based on the analyses summarized in this report, a pathway is recommended for a rigorous and technology-neutral MSR source term analysis in the U.S.

A Pathway for the Development of Advanced Reactor Mechanistic Source Term Modeling and Simulation Capabilities

“…The long-term objectives for MSR and FHR MST mod/sim are briefly described here and are in accordance with the important phenomena, relevant computational capabilities, and the resulting information gaps which have been outlined in previous reports [4,5] and expand on recent efforts in MSR MST model development [9,10]. The long-term development objectives are summarized below and are described in more detail in Appendix B: Because MSRs are strongly multiphysics in nature, many of the above development objectives are cross-cutting with other MSR-related research programs.…”

Survey and Assessment of Computational Capabilities for Advanced (Non-LWR) Reactor Mechanistic Source Term Analysis.

“…Recently, Jerden et al outlined a path forward for the development of a MST approach for MSRs that is both rigorous and technology neutral [193]. They conclude there remains a need for a thorough, step-by-step source term analyses that includes parametric sensitivity analyses and trial calculations.…”

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

“…The primary challenge to developing MSTs for non-LWR advanced reactor concepts is that it likely requires the development of new modeling tools (or the significant alteration of existing codes) and may require a significant experimental program to obtain the fundamental chemical and transport data needed to implement mechanistic models. Initial work defining data needs for the development of an MST model for liquid fueled MSRs was discussed in Jerden et al, 2019a and an experimental program providing the type of thermophysical, thermochemical, and modeling tools has been implemented within the Molten Salt Reactors Campaign. This report provides an in-depth critical review of the information sources that will form the basis for a state-of-the-art MST model for liquid fueled MSRs.…”

“…Instead of using a bounding accident approach, MSTs consider the real transport and retention processes, use fundamental chemistry knowledge, and consider the effects of barriers to release (Jerden et al, 2019a). Unrealistic guidance provided by a conservative bounding source term approach could promote decisions that negatively impact safety.…”

“…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). This section provides information addressing the first objective in Figure 1: identify and characterize radionuclide sources.…”