SEEPAGE MODEL FOR PA INCLUDING DRIFT COLLAPSE

Technical Report · Wed Sep 22 04:00:00 EDT 2004

DOI:https://doi.org/10.2172/841253· OSTI ID:841253

Tsang, C

The purpose of this report is to document the predictions and analyses performed using the seepage model for performance assessment (SMPA) for both the Topopah Spring middle nonlithophysal (Tptpmn) and lower lithophysal (Tptpll) lithostratigraphic units at Yucca Mountain, Nevada. Look-up tables of seepage flow rates into a drift (and their uncertainty) are generated by performing numerical simulations with the seepage model for many combinations of the three most important seepage-relevant parameters: the fracture permeability, the capillary-strength parameter 1/a, and the percolation flux. The percolation flux values chosen take into account flow focusing effects, which are evaluated based on a flow-focusing model. Moreover, multiple realizations of the underlying stochastic permeability field are conducted. Selected sensitivity studies are performed, including the effects of an alternative drift geometry representing a partially collapsed drift from an independent drift-degradation analysis (BSC 2004 [DIRS 166107]). The intended purpose of the seepage model is to provide results of drift-scale seepage rates under a series of parameters and scenarios in support of the Total System Performance Assessment for License Application (TSPA-LA). The SMPA is intended for the evaluation of drift-scale seepage rates under the full range of parameter values for three parameters found to be key (fracture permeability, the van Genuchten 1/a parameter, and percolation flux) and drift degradation shape scenarios in support of the TSPA-LA during the period of compliance for postclosure performance [Technical Work Plan for: Performance Assessment Unsaturated Zone (BSC 2002 [DIRS 160819], Section I-4-2-1)]. The flow-focusing model in the Topopah Spring welded (TSw) unit is intended to provide an estimate of flow focusing factors (FFFs) that (1) bridge the gap between the mountain-scale and drift-scale models, and (2) account for variability in local percolation flux due to stochastic hydrologic properties and flow processes.

• Research Organization: Yucca Mountain Project, Las Vegas, Nevada
• Sponsoring Organization: USDOE
• DOE Contract Number: AC28-01RW12101
• OSTI ID: 841253
• Report Number(s): MDL-NBS-HS-000002, REV 03; DOC.20040922.0008, DC#42948
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
COMPLIANCE
EVALUATION
FLOW RATE
FOCUSING
FRACTURES
GEOMETRY
LICENSE APPLICATIONS
PERFORMANCE
PERMEABILITY
SENSITIVITY
SHAPE
YUCCA MOUNTAIN