7 research outputs found
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Use of Dissolved and Colloidal Actinide Parameters within the 1996 Waste Isolation Pilot Plant Compliance Certification Application
Many of the papers in this volume present detailed descriptions of the chemical analyses and methodologies that have been used to evaluate the maximum dissolved and colloid concentrations of actinides within the WIPP repository as part of the performance assessment. This paper describes the program fcm collecting experimental data and provides an overview of how the PA modeled the release of radionuclides to the accessible environment, and how volubility and colloid parameters were used by the PA models
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A conceptual performance assessment model of the dissolved actinide source term for the WIPP
This paper presents a performance assessment model of dissolved actinide concentrations for the Waste Isolation Pilot Plant (WIPP). The model assesses the concentration of each actinide oxidation state and combines these concentrations with an oxidation state distribution. The chemical behavior of actinides in the same oxidation state is presumed to be very similar for almost all situations, but exceptions arising from experimental evidence are accommodated. The code BRAGFLO calculates the gas pressure, brine mass, gas volume, and mass of remaining Fe and cellulosics for each time step and computational cell. The total CO{sub 2} in the repository and dissolved Ca(OH){sub 2} is estimated. Lookup tables are constructed for pmH and f(CO{sub 2}) as a function of brine type and volume, moles of CO{sub 2}, and Ca(OH){sub 2}. Amounts of five soluble complexants are considered. A model based on the formulation of Harvie et al. produces tables of solubilities for each actinide oxidation state as a function of pmH, f(CO{sub 2}), brine composition, and complexant. Experimental data yield lookup tables of fractions of Th, U, Np, Pu, and Am in each oxidation state as a function of f(CO{sub 2}) and complexant. The tables are then used to provide a concentration of a particular actinide at particular values of pmH and f(CO{sub 2}). Under steady-state conditions, the oxidation state of each actinide that is most stable in the particular chemical environment controls the concentration of that actinide in solution. In the absence of steady-state conditions, the oxidation state distribution of interest is that of the dissolved actinide, and the oxidation states may be treated as if they were separate compounds
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Solubility Evaluation for Yucca Mountain TSPA-SR
A systematic evaluation of radionuclide solubility has been conducted for the Yucca Mountain Project. The conventional thermodynamic approach was employed and geochemical model calculations were used to estimate radionuclide solubilities for the base case. The study uses the computer code EQ3/6 as the major geochemical modeling tool. The water composition and environmental conditions are based on the results of in-package chemistry and in-drift chemistry studies. Field observations, laboratory measurements, and thermodynamic and kinetic considerations are utilized to ensure the resulting solubilities are conservative. Fourteen radioelements have been studied (U, Np, Pu, Th, Am, Ac, Tc, I, C, Cs, Sr, Ra, Pa, and Pb) and their solubilities are presented as either functions of environmental conditions or statistical distributions. Alternative solubility models for Np and Pu were also developed. These alternative models are based on measurements of spent fuel dissolution experiments rather than conventional thermodynamic considerations. Comparison of the Np and Pu base case models with their alternative models suggests that they are needed in order to advance our understanding about the behaviors of Np and Pu during the process of spent fuel corrosion
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Consideration of criticality in a nuclear waste repository
The preliminary criticality analysis that was done suggests that the possibility of achieving critical conditions cannot be easily ruled out without looking at the geochemical process of assembly or the dynamics of the operation of a critical assembly. The evaluation of a critical assembly requires an integrated, consistent approach that includes evaluating the following: (1) the alteration rates of the layers of the container and spent fuel, (2) the transport of fissile material or neutron absorbers, and (3) the assembly mechanisms that can achieve critical conditions. The above is a non-trivial analysis and preliminary work suggests that with the loading assumed, enough fissile mass will leach from the HEU multi-purpose canisters to support a criticality. In addition, the consequences of an unpressurized Oklo type criticality would be insignificant to the performance of an unsaturated, tuff repository
Monetary policy and multiple equilibria with constrained investment and externalities
Interest rate rules, Determinacy, Investment, Monetary policy, E4, E52, E61, E62, E63,
PLANNED INCAPACITY TO SUCCEED? POLICY-MAKING STRUCTURE AND POLICY FAILURE
Policies may fail in two analytically distinct ways: they may fail to achieve their goals, or they may fail to retain political support and be terminated. By failing to distinguish between ineffectiveness and political failure, the three most common interpretations of the War on Poverty and the Comprehensive Employment and Training Act (failure owing to central government incompetence, failure owing to pluralism, and "hidden" success) cannot adequately account for the gap between their ambiguous performance and their clear political failure. To understand these differences, one must understand the effect of America's fragmented political structure on the design and implementation of poverty and unemployment remedies. Under resource constraints and given a large degree of policy discretion, American states in the aggregate have retained their historic resistance to social policies that would increase short-term expenditures and reduce the attractiveness of their business climate. These jurisdictions and their Congressional representatives opposed new fully nationalized initiatives, insisting on policy designs that promised fiscal relief while protecting state and local policy control. National policymakers found that grant-in-aid programs offered the path of least resistance in these circumstances. Although social policy grant programs could win initial approval in Congress, these designs proved to be increasingly unwieldy, expensive, and difficult to control in practice. The programs yielded ambiguous overall results but provided unambiguous examples of waste, fraud and abuse, fueling the perception of failure and contributing to the backlash against these programs and their political failure. Copyright 1988 by The Policy Studies Organization.