E-Area Vault Concrete Material Property And Vault Durability/Degradation Projection Recommendations

Abstract

Subsequent to the 2008 E-Area Low-Level Waste Facility (ELLWF) Performance Assessment (PA) (WSRC 2008), two additional E-Area vault concrete property testing programs have been conducted (Dixon and Phifer 2010 and SIMCO 2011a) and two additional E-Area vault concrete durability modeling projections have been made (Langton 2009 and SIMCO 2012). All the information/data from these reports has been evaluated and consolidated herein by the Savannah River National Laboratory (SRNL) at the request of Solid Waste Management (SWM) to produce E-Area vault concrete hydraulic and physical property data and vault durability/degradation projection recommendations that are adequately justified for use within associated Special Analyses (SAs) and future PA updates. Based upon this evaluation the following are recommended in regards to the E-Area vault concrete property values for use in ELLWF SAs and PAs: • Utilize the property values provided in Table 5-1 for saturated hydraulic conductivity, tortuosity, effective diffusion coefficient, dry bulk density, porosity, and particle density. • Utilize the characteristic curve data provided in Table 3-8. • Utilize the uncertainty distributions provided in Table 3-10. The Low Activity Waste (LAW) and Intermediate Level (IL) Vaults structural degradation predictions produced by Carey 2006 and Peregoy 2006, respectively, which were used as the basis for the 2008 ELLWF PA, remain valid based upon the results of the E-Area vault concrete durability simulations reported by Langton 2009 and those reported by SIMCO 2012. Therefore revised structural degradation predictions are not required so long as the mean thickness of the closure cap overlying the vaults is no greater than that assumed within Carey 2006 and Peregoy 2006. For the LAW Vault structural degradation prediction (Carey 2006), the mean thickness of the overlying closure cap was taken as nine feet. For the IL Vault structural degradation prediction (Peregoy 2006), the mean thickness of the overlying closure cap was taken as eight feet. The mean closure cap thicknesses as described here for both E-Area Vaults will be included as a key input and assumption (I&A) in the next revision to the closure plan for the ELLWF (Phifer et al. 2009). In addition, it has been identified as new input to the PA model to be assessed in the ongoing update to the new PA Information UDQE (Flach 2013). Once the UDQE is approved, the SWM Key I&A database will be updated with this new information.

Hydraulic Properties Data Package for the E-Area Soils, Cementitious Materials, and Waste Zones - Update

“…The SIMCO results are considered to be the most accurate of the E-Area vault concrete testing todate because SIMCO is a leader in the field and the test methodology was designed specifically for cementitious materials. Phifer (2014) recommended the nominal property values shown in Table 6-24 for use in future PA and Special Analysis (SA) modeling.…”

Technical Approach for Determining Key Parameters Needed for Modeling the Performance of Cast Stone for the Integrated Disposal Facility Performance Assessment

“…Several methods have been reported for measuring the intrinsic permeability or saturated hydraulic conductivity of concretes (Rockhold et al 1993;Phifer 2014;Jones & Grasley 2009). The three methods are: hollow flow-through, hollow dynamic pressurization, and flexible wall permeameter.…”

“…According to the drying test method, equilibrium of 10-mm-thick specimens is considered to be reached when four successive mass changes determined at intervals of seven days exhibit less than 0.5% of the cumulative mass loss. The mass loss of the 50-mm series is then analyzed with the moisture transport model developed by SIMCO Technologies to yield the intrinsic permeability (Phifer 2014). Briefly, the test was performed in a climate chamber.…”

Hydraulic Properties Data Package for the E-Area Soils, Cementitious Materials, and Waste Zones–Update

“…Hydraulic properties for 4000-SCC-FA-Grout are discussed in section 6.3.3.2. Hydraulic and physical properties and van Genuchten parameters for samples of mix 4000-SCC-FA-GROUT are listed in (Phifer, 2014) Concrete cores were collected from the E-Area LLWF ILV/LAWV concrete test wall in 2010 and submitted to SIMCO Technologies Inc. to evaluate hydraulic and physical properties of the concrete. The E-Area LLWF ILV/LAWV concrete test wall was constructed in 1991 utilizing the same concrete formulation as the LAWV and ILV, mix C-4000-8-S-2-AB, and was placed and cured in the same manner.…”

“…26. Salts used in constant vapor pressure method for moisture retention characteristics and resulting saturation of vault concrete sample (Phifer, 2014). …”