MELCOR/CONTAIN LMR Implementation Report - FY16 Progress.

This report describes the progress of the CONTAIN-LMR sodium physics and chemistry models to be implemented in MELCOR 2.1. In the past three years, the implementation included the addition of sodium equations of state and sodium properties from two different sources. The first source is based on the previous work done by Idaho National Laboratory by modifying MELCOR to include liquid lithium equation of state as a working fluid to model the nuclear fusion safety research. The second source uses properties generated for the SIMMER code. The implemented modeling has been tested and results are reported in this document. In addition, the CONTAIN-LMR code was derived from an early version of the CONTAIN code and many physical models that were developed since this early version of CONTAIN are not available in this early code version. Therefore, CONTAIN 2 has been updated with the sodium models in CONTAIN-LMR as CONTAIN2-LMR, which may be used to provide code-to-code comparison with CONTAIN-LMR and MELCOR when the sodium chemistry models from CONTAIN-LMR have been completed. Both the spray fire and pool fire chemistry routines from CONTAIN-LMR have been integrated into MELCOR 2.1 and debugging and testing are in progress. Because MELCOR only models the equation of state for liquid and gas phases of the coolant, a modeling gap still exists when dealing with experiments or accident conditions that take place when the ambient temperature is below the freezing point of sodium. An alternative method is under investigation to overcome this gap. We are no longer working on the separate branch from the main branch of MELCOR 2.1 since the major modeling of MELCOR 2.1 has been completed. At the current stage, the newly implemented sodium chemistry models will be a part of the main MELCOR release version (MELCOR 2.2). This report will discuss the accomplishments and issues relating to the implementation. Also, we will report on the planned completion of all remaining tasks in the upcoming FY2017, including the atmospheric chemistry model and sodium-concrete interaction model implementation.