A Framework for Assessing the Cost and Financing Uncertainties of the Belgian High Level-Waste Repository

2003 ◽  
Author(s):  
P. L. Kunsch
Keyword(s):  
Fuzzy Logic ◽  
Electric Power Research Institute ◽  
High Level Waste ◽  
Mathematical Technique ◽  
Final Design ◽  
High Level ◽  
The Cost ◽  
Fuzzy Logic Technique ◽  
Hlw Repository ◽  
Natural Way

This paper presents the general approach presently developed by ONDRAF/NIRAS/NERAS, the Belgian radioactive waste management agency for dealing with the economic and financial uncertainties of the High-level-Waste (HLW) repository project in clay. This project will be for many more years the object of R&D studies. Many uncertainties thus still exist regarding the final design, the eventual costs, and the realisation schedule. Recommendations from the Electric Power Research Institute (EPRI) are available for computing contingency factors to be applied on top of the basic costs delivered by project engineers. We show in this paper that fuzzy logic is a natural way to use the recommendations of EPRI. Fuzzy logic is a mathematical technique for representing unprecise or relatively vague judgments made by experts, like: ‘this project is preliminary’, ‘this concept is insufficiently mature’, etc. This approach is considered in many fields as being well-suited for coping with uncertainties implied by such judgments. In the present case, distinction is made between uncertainties related to policy, project, technology, and realisation schedule. The paper details the sequence of basic steps used by the agency to produce as a final product the per-unit tariff of the different waste categories. Expert judgments are interpreted by the fuzzy-logic technique to derive EPRI-like contingency factors for each project task, as well as a fuzzy operating schedule within a given political scenario. Conclusions are given on how this approach can be validated and set into practice.

scholarly journals Reactive transport calculations to evaluate sulphide fluxes in the near-field of a SF/HLW repository

2019 ◽  
Vol 98 ◽  
pp. 10005
Author(s):  
Marek Pękala ◽  
Paul Wersin ◽  
Veerle Cloet ◽  
Nikitas Diomidis
Keyword(s):  
Reactive Transport ◽  
Spent Nuclear Fuel ◽  
Near Field ◽  
Opalinus Clay ◽  
High Level Waste ◽  
Waste Containment ◽  
Geological Repository ◽  
High Level ◽  
Reducing Bacteria ◽  
Hlw Repository

Radioactive waste is planned to be disposed in a deep geological repository in the Opalinus Clay (OPA) rock formation in Switzerland. Cu coating of the steel disposal canister is considered as potential a measure to ensure complete waste containment of spent nuclear fuel (SF) and vitrified high-level waste (HLW) or a period of 100,000 years. Sulphide is a potential corroding agent to Cu under reducing redox conditions. Background dissolved sulphide concentrations in pristine OPA are low, likely controlled by equilibrium with pyrite. At such concentrations, sulphide-assisted corrosion of Cu would be negligible. However, the possibility exists that sulphate reducing bacteria (SRB) might thrive at discrete locations of the repository’s near-field. The activity of SRB might then lead to significantly higher dissolved sulphide concentrations. The objective of this work is to employ reactive transport calculations to evaluate sulphide fluxes in the near-field of the SF/HLW repository in the OPA. Cu canister corrosion due to sulphide fluxes is also simplistically evaluated.

The Effect of Temperature and Composition on Spinel Concentration and Crystal Size in High-Level Waste Glass

2001 ◽  
Author(s):  
Martin Mika ◽  
Milan Patek ◽  
Jaroslav Maixner ◽  
Simona Randakova ◽  
Pavel Hrma
Keyword(s):  
Crystal Size ◽  
Equilibrium Concentration ◽  
Effect Of Temperature ◽  
High Level Waste ◽  
Huge Number ◽  
Aluminoborosilicate Glass ◽  
High Level ◽  
The Cost ◽  
Different Content ◽  
The Mathematical Model

Abstract High-level radioactive wastes can be safely immobilized in alkali-aluminoborosilicate glass. To reduce the cost of the vitrification process, the waste loading should be maximized. This can be done by optimizing the process using mathematical modeling. The main objective of our work was to determine one of the necessary inputs for the mathematical model, which is the effect of temperature and composition on the concentration of spinel crystals and their size. We prepared six glasses with a different content of Li+, Na+, Mg2+, Ni2+, Cr3+, and SiIV and studied the effect of composition on the temperature dependence of spinel equilibrium concentration in glass by X-ray powder diffraction. The size of crystals was determined using optical microscopy. It was found that the temperature effect on spinel concentration significantly increased as the content of Ni2+ or Mg2+ in glass increased and slightly decreased as the content of Cr3+ increased and Li+ and Na+ content decreased. Both Ni2+ and Cr3+ acted as nucleating agents, producing a huge number of tiny spinel crystals (∼2 μm). In particular, Ni2+ seems to very significantly facilitate spinel crystallization.

Animated fuzzy logic

1998 ◽  
Vol 8 (5) ◽  
pp. 503-525 ◽  
Author(s):  
GARY MEEHAN ◽  
MIKE JOY
Keyword(s):  
Fuzzy Logic ◽  
Functional Language ◽  
Fuzzy Subset ◽  
High Level ◽  
Natural Way

In this paper we aim to give an introduction to fuzzy logic using the language Haskell to implement our solutions. We shall see how the high-level, declarative nature of a functional language allows us to implement easily and efficiently solutions to problems using fuzzy logic and, in particular, how the presence of functions as first-class values allows us to model the key concept of the fuzzy subset in a natural way.

Transparent Tools for Uncertainty Analysis in High Level Waste Disposal Facilities Safety

2007 ◽  
Author(s):  
Francisco Luiz de Lemos ◽  
Karl-Heinz Helmuth ◽  
Terry Sullivan
Keyword(s):  
Fuzzy Logic ◽  
Uncertainty Analysis ◽  
Waste Disposal ◽  
Computational Models ◽  
Cognitive Mapping ◽  
Data Interpretation ◽  
High Level Waste ◽  
Rock Interaction ◽  
And Migration ◽  
High Level

In this paper some results of a further development of a technical cooperation project, initiated in 2004, between the CDTN/CNEN, The Brazilian National Nuclear Energy Commission, and the STUK, The Finnish Radiation and Nuclear Safety Authority, are presented. The objective of this project is to study applications of fuzzy logic, and artificial intelligence methods, on uncertainty analysis of high level waste disposal facilities safety assessment. Uncertainty analysis is an essential part of the study of the complex interactions of the features, events and processes, which will affect the performance of the HLW disposal system over the thousands of years in the future. Very often the development of conceptual and computational models requires simplifications and selection of over conservative parameters that can lead to unrealistic results. These results can mask the existing uncertainties which, consequently, can be an obstacle to a better understanding of the natural processes. A correct evaluation of uncertainties and their rule on data interpretation is an important step for the improvement of the confidence in the calculations and public acceptance. This study focuses on dissolution (source), solubility and sorption (sink) as key processes for determination of release and migration of radionuclides. These factors are affected by a number of parameters that characterize the near and far fields such as pH; temperature; redox conditions; and other groundwater properties. On the other hand, these parameters are also consequence of other processes and conditions such as water rock interaction; pH and redox buffering. Fuzzy logic tools have been proved to be suited for dealing with interpretation of complex, and some times conflicting, data. For example, although some parameters, such as pH and carbonate, are treated as independent, they have influence in each other and on the solubility. It is used the technique of fuzzy cognitive mapping is used for analysis of effects of variations on one parameter on the others in a system. This technique uses the concept of fuzzy sets to represent the “quality” of the relation between parameters rather then deterministic numbers.

scholarly journals High-level waste canister storage final design, installation, and testing. Topical report

1998 ◽  
Author(s):  
B.J. Connors ◽  
R.A. Meigs ◽  
D.M. Pezzimenti ◽  
P.M. Vlad
Keyword(s):  
High Level Waste ◽  
Final Design ◽  
High Level

Numerical and Experimental Investigations on the Time Dependent Behaviour of a Salt Dome With a High-Level Waste Repository

1983 ◽  
Vol 26 ◽  
Author(s):  
Jan Prij ◽  
Leo H. Vons
Keyword(s):  
Elevated Temperatures ◽  
Salt Dome ◽  
Time Dependent ◽  
High Level Waste ◽  
Experimental Investigations ◽  
Time Dependent Behaviour ◽  
High Level ◽  
Hlw Repository ◽  
Dependent Behaviour

ABSTRACTResults are presented of in-situ measurements, performed in a 300 m deep dry-drilled borehole, in the ASSEmine. Convergence measurements at ambient as well as elevated temperatures and pressure measurements at elevated temperatures are discussed. Creep equations derived from these experiments are used for the numerical analysis of the time dependent behaviour of a salt dome with a HLW repository. The analyses show that the total stresses in the salt remain compressive with deviatoric components smaller than 3 MPa.

Investigations of the Possible Separation Distance Between Spent Fuel/High-Level Waste and a Low/Intermediate-Level Waste Repositories due to Gas and Heat Generation

2011 ◽  
Author(s):  
R. Senger ◽  
J. Ewing
Keyword(s):  
Heat Generation ◽  
Thermal Effects ◽  
Intermediate Level ◽  
High Level Waste ◽  
Spent Fuel ◽  
Gas Generation ◽  
Pressure Buildup ◽  
Thermally Induced ◽  
High Level ◽  
Hlw Repository

This study is part of a generic investigation for the assessment of the required minimum distance between a Spent Fuel/High-Level Waste/ Intermediate-Level Waste (SF/HWL/ILW) repository and a Low/ Intermediate-Level Waste (L/ILW) repository. For this, a large-scale numerical model was constructed to investigate the two-phase flow behavior for such a repository configuration in a low-permeability claystone formation. The modeling focused on the pressurization mechanisms associated with (a) resaturation of backfilled underground facilities, (b) thermal effects caused by heat generation from the SF/HLW canisters, and (c) gas generation from corrosion and degradation of different wastes in the L/ILW and ILW caverns and in the SF/HLW emplacement tunnels. The model accounts for gas generation from corrosion and degradation of both L/ILW and ILW wastes indicating decreasing rates with time, and from corrosion of the SF/HLW canisters characterized by a constant rate. Heat generation from radioactive decay of radionuclides of MOX/UO2 wastes is described by an exponential decay with time. The preceding operational phases of the different repository components were simulated representing the transient initial conditions for the post-closure phase. The simulated pressure buildup in the L/ILW repository shows a near linear increase between 10 and 4,000 years when the peak pressure of 6.5 MPa is reached for a repository at about 370 m bg. This is followed by a similar decline, recovering to near hydrostatic pressures after 1 million years. The SF/HLW repository (repository level 600 m bg) indicates a pressure rise between 100 and 1,000 years affected by the early thermal effects, followed by a steep increase between 3,000 and 100,000 years when the pressures level off to a maximum of 6.5 MPa after 160,000 years (corresponding to a steel corrosion rate of 1 μm/year). This is the time when all the metal is corroded and the gas generation stops resulting in a sudden decline, and the pressures level off to about 4.5 MPa in the SF/HLW emplacement tunnel after 1 million years. The numerical modeling demonstrates that the main pressurization mechanism is from gas generation in the different repository components. The pressure histories show a distinct separation of the pressure peaks between the L/ILW repository and the SF/HLW/ILW repository. Moreover, the thermal phenomena affect the pressures in the SF/HLW repository at early time only (prior to about 2,000 years). The thermal expansion of the pore water in the nearfield around the SF/HLW tunnels does produce a relatively steep pressure buildup after 100 years, but it dissipates rapidly prior to the main pressure buildup caused by the gas generation and gas accumulation in the SF/HLW repository. The thermally induced pressure buildup is restricted to the vicinity of the SF/HLW emplacement tunnels (decameter range) and thus, significant interference of the thermally induced pressure perturbation around the SF/HLW/ILW repository with the early gas pressure buildup in the L/ILW repository can be excluded.

Evaluation of the Possible Susceptibility of Titanium Grade 7 to Hydrogen Embrittlement in a Geologic Repository Environment

2000 ◽  
Vol 663 ◽  
Author(s):  
Charles A. Greene ◽  
Alvin J. Henry ◽  
C. Sean Brossia ◽  
Tae M. Ahn
Keyword(s):  
Hydrogen Embrittlement ◽  
High Level Waste ◽  
Geologic Repository ◽  
Hydride Formation ◽  
Enhanced Resistance ◽  
Ti Alloys ◽  
Titanium Grade ◽  
High Level ◽  
Hlw Repository ◽  
The U.S

ABSTRACTTi grade 7 has been selected by the U.S. DOE as the current material of choice for the drip shield in the proposed high level waste (HLW) repository design. Due to the addition of Pd, Ti grade 7 exhibits enhanced resistance to hydrogen embrittlement (HE), yet there is relatively little data on HE of this material. Calculations of hydrogen absorption/recombination, solubility, and free energy of hydride formation in Ti and Pd are presented to qualitatively evaluate Keff, the stress intensity factor for crack propagation induced by hydride formation, of Ti grade 7 in relation to other Ti alloys without Pd. Calculations were performed that show concentration of hydrogen in Ti grade 7 may exceed the critical hydrogen concentration, Hc, where the material becomes embrittled, when accelerated passive dissolution of Ti grade 7 in concentrated Cl- and Cl-+F- solutions as the source of hydrogen is considered.

The role of the canister in a system for the final disposal of spent fuel or high-level waste

1986 ◽  
Vol 319 (1545) ◽  
pp. 39-47 ◽  
Keyword(s):  
Crystalline Rock ◽  
High Level Waste ◽  
Public Confidence ◽  
Toxic Substances ◽  
Spent Fuel ◽  
Geochemical Environment ◽  
Safety Margins ◽  
Safety Effect ◽  
High Level ◽  
The Cost

A final repository for radioactive waste must isolate the toxic substances or distribute their release over time or space to avoid causing harmful concentrations of radionuclides in the biosphere. The Swedish research has focused on a repository 500 m down in crystalline rock where the geochemical environment can give canisters a service life of the order of a million years. These evaluations are discussed and the safety effect of the canister is compared with that of other barriers available in a repository system. Our conclusions are that a combined protection effect of natural and man-made barriers can be achieved that substantially exceeds what could reasonably be required by society. An actual repository design can then be based on an optimization of the cost to reach a level of accepted safety with due regard for the safety margins and redundancy necessary for achieving public confidence.

Application of the Monte Carlo Method in the Performance Assessment of a Hypothetical HLW Repository in Salt

1988 ◽  
Vol 127 ◽  
Author(s):  
Alexander Nies
Keyword(s):  
Monte Carlo ◽  
Safety Assessment ◽  
Salt Dome ◽  
High Level Waste ◽  
Parameter Uncertainties ◽  
Output Uncertainty ◽  
The Monte Carlo Method ◽  
Waste Repository ◽  
High Level ◽  
Hlw Repository

ABSTRACTRecent advances in complementing the capabilities of our safety assessment code development allow for an explicit investigation of the consequences of parameter uncertainties by Monte Carlo simulation of the disposal system. The implemented methods aire described and applied to impact assessment of a brine intrusion scenario on a high level waste repository in a salt dome. Results display the strong effect of parameter uncertainties on the analysis results. With help of several sensitivity estimators input parameters are ranked according to their influence on output uncertainty.

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