scholarly journals An introduction to the mechanics of performance assessment using examples of calculations done for the Waste Isolation Pilot Plant between 1990 and 1992

1995 ◽  
Author(s):  
R.P. Rechard
Keyword(s):  
Performance Assessment ◽  
Pilot Plant ◽  
Waste Isolation Pilot Plant

Influence of Carbonate on Uranium Solubility in the WIPP

2012 ◽  
Vol 1444 ◽  
Author(s):  
Jean-Francois Lucchini ◽  
Sally Ballard ◽  
Hnin Khaing
Keyword(s):  
Performance Assessment ◽  
Pilot Plant ◽  
Solubility Limit ◽  
Experimental Results ◽  
Waste Isolation Pilot Plant ◽  
Long Term Experiments ◽  
Order Of Magnitude ◽  
Carbonate Complexation ◽  
Borate Complexation

ABSTRACTIn the performance assessment (PA) for the Waste Isolation Pilot Plant (WIPP), the solubility of uranium (VI) was conservatively set at 10-3 M for all expected WIPP conditions, including the potential and likely effects of carbonate complexation [1]. Under WIPP-relevant conditions, long-term experiments were performed to establish the uranium (VI) solubility limits in WIPP-simulated brine over a broad range of pCH+ values [7.5-12.5] and to evaluate the contribution of carbonate complexation and hydrolysis to uranium (VI) speciation. Data obtained in carbonate-free ERDA-6 brine, a simulated WIPP brine, were reported earlier [2]. In the absence of carbonate, uranium solubility approached 10-7 M at the expected pCH+ in the WIPP (~ 9.5). In the presence of a significant amount of carbonate (millimole levels), recent experimental results showed that uranium (VI) concentrations will not exceed 10-4M. This measured solubility limit is an order of magnitude lower than the uranium solubility value currently used in the WIPP PA [3]. A small effect of borate complexation was found in the pCH+ range [7.5-10]. At pCH+ ≥ 10, hydrolysis overwhelmed carbonate effects, and no amphoteric effect was observed.

scholarly journals Regulatory basis for the Waste Isolation Pilot Plant performance assessment

2000 ◽  
Vol 69 (1-3) ◽  
pp. 109-127 ◽  
Author(s):  
B.A Howard ◽  
M.B Crawford ◽  
D.A Galson ◽  
M.G Marietta
Keyword(s):  
Performance Assessment ◽  
Pilot Plant ◽  
Plant Performance ◽  
Waste Isolation Pilot Plant

Establishment of Uncertainty Ranges and Probability Distributions of Actinide Solubilities for Performance Assessment in the Waste Isolation Pilot Plant

2010 ◽  
Vol 1265 ◽  
Author(s):  
Yongliang Xiong ◽  
Jim Nowak ◽  
Laurence H. Brush ◽  
Ahmed E. Ismail ◽  
Jennifer Long
Keyword(s):  
Ionic Strength ◽  
Performance Assessment ◽  
Oxidation State ◽  
Pilot Plant ◽  
Probability Distributions ◽  
Waste Isolation Pilot Plant ◽  
Activity Coefficient Model ◽  
Binary Mixing ◽  
Compliance Certification ◽  
Compliance Certification Application

AbstractThe Fracture-Matrix Transport (FMT) code developed at Sandia National Laboratories solves chemical equilibrium problems using the Pitzer activity coefficient model with a database containing actinide species. The code is capable of predicting actinide solubilities at 25 °C in various ionic-strength solutions from dilute groundwaters to high-ionic-strength brines. The code uses oxidation state analogies, i.e., Am(III) is used to predict solubilities of actinides in the +III oxidation state; Th(IV) is used to predict solubilities of actinides in the +IV state; Np(V) is utilized to predict solubilities of actinides in the +V state. This code has been qualified for predicting actinide solubilities for the Waste Isolation Pilot Plant (WIPP) Compliance Certification Application in 1996, and Compliance Re-Certification Applications in 2004 and 2009.We have established revised actinide-solubility uncertainty ranges and probability distributions for Performance Assessment (PA) by comparing actinide solubilities predicted by the FMT code with solubility data in various solutions from the open literature. The literature data used in this study include solubilities in simple solutions (NaCl, NaHCO3, Na2CO3, NaClO4, KCl, K2CO3, etc.), binary mixing solutions (NaCl+NaHCO3, NaCl+Na2CO3, KCl+K2CO3, etc.), ternary mixing solutions (NaCl+Na2CO3+KCl, NaHCO3+Na2CO3+NaClO4, etc.), and multi-component synthetic brines relevant to the WIPP.

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