Thermal Management Flexibility Analysis

The purpose of this report is to demonstrate that postclosure temperature limits can be met, and certain thermal characteristics of the postclosure thermal reference case can be preserved, with alternative thermal loading schemes. The analysis considers certain variations from the base case.waste stream, the predicted postclosure temperatures that develop within the rock mass due to these waste stream variations, and then compares these temperatures to postclosure temperature limits. The results define a preliminary "thermal envelope" based on evaluating variations to the postclosure thermal reference case, for consideration by multiple Yucca Mountain Project (YMP) organizations in developing a thermal management strategy for the repository.
Multiscale Thermohydrologic Model (BSC 2005 [DIRS 173944]) implements the postclosure thermal reference case for total system performance assessment (TSPA), based on information provided on information exchange drawings (IEDs). This is called the "base case" and the "TSPA reference case" in this report. The postclosure temperature limits considered in this report are the maximum drift-wall temperature of 200°C, and the maximum mid-pillar temperature of 96°C (BSC 2004 [DIRS 168489]; DOE 2006 [DIRS 176937], Section 4.6.5). In addition, some of the analyses presented here evaluate whether the alternative loading schemes increase the axial variation of drift-wall temperature along the drift crown, which is used as a measure of dimensionality (i.e., two-dimensional versus three-dimensional) for the temperature field and its ·effects (CRWMS M&O 1999 [DIRS 107292], Section 0.2.2.1).