scholarly journals Thermal Analysis of Geologic High-Level Radioactive Waste Packages

2010 ◽  
Author(s):  
S. Y. Lee ◽  
S. J. Hensel ◽  
C. De Bock
Keyword(s):  
Thermal Analysis ◽  
Computational Models ◽  
Thermal Characteristics ◽  
Temperature History ◽  
High Level Waste ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Geologic Repository ◽  
Sensitivity Studies ◽  
High Level

The engineering design of disposal of the high level waste (HLW) packages in a geologic repository requires a thermal analysis to provide the temperature history of the packages. Calculated temperatures are used to demonstrate compliance with criteria for waste acceptance into the geologic disposal gallery system and as input to assess the transient thermal characteristics of the vitrified HLW Package. The objective of the work was to evaluate the thermal performance of the supercontainer containing the vitrified HLW in a non-backfilled and unventilated underground disposal gallery. In order to achieve the objective, transient computational models for a geologic vitrified HLW package were developed by using a computational fluid dynamics method, and calculations for the HLW disposal gallery of the current Belgian geological repository reference design were performed. An initial two-dimensional model was used to conduct some parametric sensitivity studies to better understand the geologic system’s thermal response. The effect of heat decay, number of co-disposed supercontainers, domain size, humidity, thermal conductivity and thermal emissivity were studied. Later, a more accurate three-dimensional model was developed by considering the conduction-convection cooling mechanism coupled with radiation, and the effect of the number of supercontainers (3, 4 and 8) was studied in more detail, as well as a bounding case with zero heat flux at both ends. The modeling methodology and results of the sensitivity studies will be presented.

Thermal Performance Analysis of Geologic High-Level Radioactive Waste Packages

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Si Y. Lee ◽  
Steve J. Hensel ◽  
Chris De Bock
Keyword(s):  
Thermal Performance ◽  
Computational Models ◽  
Thermal Characteristics ◽  
Temperature History ◽  
High Level Waste ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Geologic Repository ◽  
Sensitivity Studies ◽  
High Level

The engineering design of disposal of the high level waste (HLW) packages in a geologic repository requires a thermal analysis to forecast the temperature history of the packages. Calculated temperatures are used to demonstrate compliance with criteria for waste acceptance into the geologic disposal gallery system and as input to assess the transient thermal characteristics of the vitrified HLW Package. The objective of the work was to evaluate the thermal performance of the supercontainer containing the vitrified HLW in a nonbackfilled and unventilated underground disposal gallery. In order to achieve the objective, transient computational models for a geologic vitrified HLW package were developed by using a computational fluid dynamics method, and calculations for the HLW disposal gallery of the current Belgian geological repository reference design were performed. An initial simplified two-dimensional model was used to conduct some parametric sensitivity studies to better understand the geologic system’s thermal response. The effect of heat decay, number of codisposed supercontainers, domain size, humidity, thermal conductivity, and thermal emissivity were studied. A more accurate three-dimensional model was also developed by considering the conduction–convection cooling mechanism coupled with radiation, and the effect of the number of supercontainers was studied in more detail, as well as a bounding case with zero heat flux at both ends. The modeling methodology and results of the sensitivity studies will be presented.

Thermal Analysis for Geologic Codisposal of SNF Packages

2002 ◽  
Author(s):  
Si Y. Lee
Keyword(s):  
Thermal Analysis ◽  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Peripheral Region ◽  
Waste Form ◽  
Temperature History ◽  
High Level Waste ◽  
Geologic Repository ◽  
Geologic Disposal ◽  
High Level

The engineering viability of disposal of aluminum-clad, aluminum-based spent nuclear fuel (Al-SNF) in a geologic repository requires a thermal analysis to provide the temperature history of the waste form. Calculated temperatures are used to demonstrate compliance with criteria for waste acceptance into the geologic disposal system and as input to assess the chemical and physical behavior of the waste form within the Waste Package (WP). The leading codisposal WP design proposes that a central DOE Al-SNF canister be surrounded by five Defense Waste Process Facility (DWPF) glass log canisters, that is, High-level Waste Glass Logs (HWGL’s), and placed into a WP in a geologic disposal system. A DOE SNF canister having about 0.4318m diameter is placed along the central horizontal axis of the WP. The five HWGL’s will be located around the peripheral region of the DOE SNF canister within the cylindrical WP container. The codisposal WP will be laid down horizontally in a drift repository. In this situation, two waste form options for Al-SNF disposition are considered using the codisposal WP design configurations. They are the direct Al-SNF form and the melt-dilute ingot. In the present work, the reference geologic and design conditions are assumed for the analysis even though the detailed package design is continuously evolved. This paper primarily dealt with the thermal performance internal to the codisposal WP for the qualification study of the WP containing Al-SNF. Thermal analysis methodology and decay heat source terms have been developed to calculate peak temperatures and temperature profiles of Al-SNF package in the DOE spent nuclear fuel canister within the geologic codisposal WP.

Maximum Individual Dose and Vicinity-Average Dose for a Geologic Repository

1996 ◽  
Vol 465 ◽  
Author(s):  
T. H. Pigford ◽  
E. D. Zwahlen
Keyword(s):  
Ground Water ◽  
High Level Waste ◽  
Average Dose ◽  
Geologic Repository ◽  
Dose Limit ◽  
New Approach ◽  
The Public ◽  
Quantitative Analyses ◽  
High Level ◽  
Maximum Exposure

ABSTRACTRecent proposals for a new U.S. standard for high-level waste disposal would limit the average dose to individuals in the vicinity surrounding a geologic repository. This would be a new approach to protecting the public from environmental releases of radioactivity. Heretofore, criteria adopted for geologic disposal have limited the reasonable maximum exposure to a future hypothetical individual. Here we present quantitative analyses of the relation between maximum exposure and vicinity-average exposure, resulting from future human use of ground water contaminated by radioactive releases from a repository.Estimating the vicinity-average exposure would require postulates and guesses of location and habits of future people. Exposure probabilities postulated by others show that proposed dose limit to the vicinity-average individual would be a far more lenient standard than the traditional dose limit to reasonably maximally exposed individuals. The proposed vicinity-average dose limit would allow far greater concentrations of contaminants in ground water than would be allowed by normal standards of ground water protection. A safety standard that limits vicinity-average exposure should also include limits on maximum exposure.

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.

U.S. Department of Energy’s High-Level Waste Program: Opportunities and Challenges in Achieving Risk and Cost Reductions

2003 ◽  
Author(s):  
Robin Nazzaro ◽  
William Swick ◽  
Nancy Kintner-Meyer ◽  
Thomas Perry ◽  
Carole Blackwell ◽  
...  
Keyword(s):  
South Carolina ◽  
Program Management ◽  
Department Of Energy ◽  
High Level Waste ◽  
Geologic Repository ◽  
Management Actions ◽  
Technical Challenges ◽  
Treatment And Disposal ◽  
High Level ◽  
The U.S

The U.S. Department of Energy (DOE) oversees one of the largest cleanup programs in history—the treatment and disposal of 356,260 cubic meters of highly radioactive nuclear waste created as a result of the nation’s nuclear weapons program. This waste is currently stored at DOE sites in the states of Washington, Idaho, and South Carolina. In 2002, DOE began an accelerated cleanup initiative to reduce the estimated $105-billion cost and 70-year time frame required for the program. The U.S. General Accounting Office (GAO), an agency of the U.S. Congress, evaluated DOE’s high-level waste program to determine the status of the accelerated cleanup initiative, the legal and technical challenges DOE faces in implementing it, and any further opportunities to improve program management. GAO found that DOE’s initiative for reducing the cost and time required for cleaning up high-level waste is evolving. DOE’s main strategy continues to include concentrating much of the radioactivity into a smaller volume for disposal in a geologic repository. Under the accelerated initiative, DOE sites are evaluating other approaches, such as disposing of more of the waste on site or at other designated locations. DOE’s current savings estimate for these approaches is $29 billion, but the estimate is not based on a complete assessment of costs and benefits and has other computational limitations. For example, the savings estimate does not adequately reflect the timing of when savings will be realized, which distorts the actual amount of savings DOE may realize. DOE faces significant legal and technical challenges to realize these savings. A key legal challenge involves DOE’s authority to decide that some waste with relatively low concentrations of radioactivity can be disposed of on site. A recent court ruling against DOE is a major threat to DOE’s ability to meet its accelerated schedules. A key technical challenge is DOE’s approach for separating waste into high-level and low-activity portions. At the Hanford Site in Washington State, DOE is planning to implement such a method that will not be fully tested until the separations facility is constructed. This approach increases the risk and cost of schedule delays compared to fully testing an integrated pilot-scale facility. However, DOE believes the risks are manageable and that a pilot facility would unnecessarily delay waste treatment and disposal. DOE has opportunities to improve management of the high-level waste program. When it began the initiative to reduce costs and accelerate the high-level waste cleanup schedule, DOE acknowledged it had systematic problems with the way the program was managed. Although DOE has taken steps to improve program management, GAO has continuing concerns about management weaknesses in several areas. These include making key decisions without a sufficiently rigorous supporting analysis, incorporating technology before it is sufficiently tested, and pursuing a “fast-track” approach of simultaneous design and construction of complex nuclear facilities. DOE’s management actions have not fully addressed these weaknesses.

Performance Evaluation of Thermal Attributes in Impinging Jet Heat Sink using Airfoil Pillars with and without Nano Fluid

2021 ◽  
Vol 7 (5) ◽  
pp. 2808-2820
Author(s):  
Deepak Kumar ◽  
Mohammad Zunaid ◽  
Samsher Gautam
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Three Dimensional ◽  
Thermal Characteristics ◽  
Exchange Coefficient ◽  
Dimensional Model ◽  
Heat Exchange Coefficient ◽  
Three Dimensional Model ◽  
Nano Fluid ◽  
Nano Fluids

Objectives: In the current research three techniques have been operated to enhance the rate of heat transfer in a heat sink. The amalgamation of Impingement of jet, airfoil pillars and Nano fluids are used. Nano fluids has a lot of potential to enhance the heat transportation in contrast to the water. The investigation has been executed with the help of three dimensional numerical model using Computational fluid Dynamics. At the onset the model has been validated with the inspection carried out already in experimental form. The observations in the form of thermal attributes are investigated. From the results the conclusion is made that the use of airfoil pillars and Nano fluids has increased the thermal characteristics of the three dimensional model in the form of heat exchange coefficient by almost 28.2%. The Nano fluid has been utilized for the 0.5% concentration.

Thermal Analysis of Options for Spent Fuel Disposal in Switzerland

1996 ◽  
Vol 465 ◽  
Author(s):  
Tetsuo Sasaki ◽  
Kenichi Ando ◽  
Hideki Kaw Amura ◽  
Jürg W. Schneider ◽  
Ian G. McKinley
Keyword(s):  
Thermal Analysis ◽  
Basic Concept ◽  
Crystalline Basement ◽  
Opalinus Clay ◽  
High Level Waste ◽  
Spent Fuel ◽  
Compacted Bentonite ◽  
High Level ◽  
Host Rocks

ABSTRACTIn parallel to studies of disposal of vitrified high-level waste from reprocessing, projects have been initiated to examine options for direct disposal of spent fuel in Switzerland. The basic concept involves in-tunnel emplacement of encapsulated spent fuel in a deep repository which is backfilled with compacted bentonite. Two possible host rocks are considered - crystalline basement and Opalinus Clay. This paper reports the results of a thermal analysis which was carried out to evaluate constraints on repository layout set by the desire to limit temperatures experienced by the bentonite backfill.

Performance Assessment with Realistic Data for a Hypothetical High-Level Waste Repository in A Salt Dome

1988 ◽  
Vol 127 ◽  
Author(s):  
R.-P. Hirsekorn ◽  
R. Storck
Keyword(s):  
Salt Dome ◽  
High Level Waste ◽  
Model Parameters ◽  
Dose Rates ◽  
Best Estimate ◽  
Time Histories ◽  
Sensitivity Studies ◽  
High Level ◽  
Physical And Chemical ◽  
Realistic Data

ABSTRACTIn the frame of the European R&D program on “Management and Storage of Radioactive Waste” assessments for HLW repositories in different geological formations have been performed with realistic data. Part of this action was the discussion of altered evolution scenarios for a repository in a salt dome.For the considered HLW repository a combined altered evolution scenario with brine intrusion via the main anhydrite vein and brine intrusion from undetected brine pockets has been considered. For this scenario limited intrusions of brine at very early times are assumed, which inundate boreholes and parts of the repository. Radionuclides are leached out of the waste forms and contaminate the brine. At later times brine intrusion via the main anhydrite is assumed to take place. Under certain conditions contact between both amounts of brine is possible, and contaminated brine reaches the overburden. Here, the radionuclides are swept away with the groundwater flow.Decisive for the transport of radionuclides from the repository to the geosphere are several interacting effects (e.g. convergence, permeability, pressure) which determine the movement of brine through the drifts and seal-ings. For the parameters involved in the modelling of physical and chemical effects as realistic data as available (best estimate) were used. Local sensitivity studies show that with the best estimate values for some parameters the combined intrusion scenario is just at the transition point between release and no release.Results are obtained showing time histories for the decrease of the voids in the repository, release rates for relevant nuclides injected into the overburden, and for dose rates. Dependences on the model parameters are discussed and most relevant parameters are identified.

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