COBRA-SFS modifications and cask model optimization

Rector, David R.; Michener, T.E.

doi:10.2172/6242345

Cited by 3 publications

(3 citation statements)

References 6 publications

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“…However, this may lead to unacceptable computer costs. Rector [Rector, 1989] presents results from a detailed analysis of the effects of mesh spacing for multi-assembly casks.…”

Section: Discussionmentioning

confidence: 99%

Modeling status and needs for temperature calculations within spent fuel disposal containers

Sullivan¹,

Pescatore²

1989

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EXECUTIVE SUMMARYMany processes relevant to long term performance of a spent fuel waste package are sensitive to the temperature within the container and of its sheU, e.g., cladding degradation, the release of 14 C from spent fuel, UO 2 oxidation, evaporation of moisture 'jvithin the container, the likely location where wetting will occur, etc. With most processes overprediction of the temperature causes a conservative prediction of the performance. For some processes, however, this is not true. For example, overprediction in temperature leads to an overprediction of the time at which water can exist in liquid form in a waste container. For these reasons, reliable waste package temperature calculations are an important concern from a performance assessment and a licensing point of view.Waste package temperatures depend on both internal factors, such as internal geometry, material properties, and heat loading, and on external factors, such as host rock properties and area! heat loading of the entire repository.The primary objective of this report is to present the findings of a literature review of work pertinent to predicting intact waste package internal temperatures under spent fuel isolation conditions. Therefore, it is assumed that a repository scale thermal analysis has been conducted and that the exterior temperature of the waste package is known. The problem then reduces to one determined by the waste package and its properties.Secondary objectives of this report are to identify key parameters and methodologies for performing the thermal analysis within intact waste containers, and identify sources of uncertainty in these calculations.Based on information supplied in the latest version of the Yucca Mountain Site Characterization Plan (SCP), three basic categories of spent fuel arrangements within the disposal containers are envisioned: a) spent fuel consolidated at the repository; b) spent fuel consolidated away from the repository in a 2:1 ratio; and c) unconsolidated spent fuel assemblies. There exist conceptual designs for each of these categories. The leading design contemplates the disposal of fuel consolidated at the repository site with argon as the backfill gas.With reference to Figure ES-1, the container for spent fuel consolidated at the repository implements an internal structure with six compartments. Within each compartment, the fuel rods occupy approximately 50% of the volume available. The rods are free to move within each compartment during handling and emplacement operations. Thus, it is unlikely that the precise geometry will be known after emplacement. For horizontal emplacement, the rods will distribute themselves under the force of gravity and it is likely that there will be large gaps around the container. For vertical emplacement (the reference emplacement strategy), the final location and shape of the gas gaps is not well defined.For preconsolidated or intact spent fuel assemblies the rods are not free to move. Thus, the internal geometry in the container is more accurately known.T...

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“…However, this may lead to unacceptable computer costs. Rector [Rector, 1989] presents results from a detailed analysis of the effects of mesh spacing for multi-assembly casks.…”

Section: Discussionmentioning

confidence: 99%

Modeling status and needs for temperature calculations within spent fuel disposal containers

Sullivan¹,

Pescatore²

1989

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“…The thermal conductivity and surface emissivity of cask component materials are given in Table 2-1 and Table 2-2. The average basket temperature was used to predict thermal expansion in McKinnon et al (1989), and the gap conductance between fuel pellet and cladding is assumed constant (Rector and Michener, 1989). (Creer et al, 1987;McKinnon et al, 1986McKinnon et al, , 1989McKinnon et al, and 1992Rector et al, 1986 (Creer et al, 1987;McKinnon et al, 1986;Rector et al, 1986a;Rector et al, 1986b (Rector et al, 1986a) Cask stainless steel inner liner 0.6 (Lombardo et al, 1986) Cask surface (stainless steel) 0.3 (Rector et al, 1986b) In addition to uncertainty in standard/reference values for thermal properties, there also exists uncertainty in the temperature dependence.…”

Section: Uncertainties In Materials Thermal Propertiesmentioning

confidence: 99%

LLNL Input to SNL Report on the Composition of Available Data for Used Nuclear Fuel Storage and Transportation Analysis

Sutton¹,

Wen²

2014

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“…A detailed study of COBRA-SFS modeling optimization has been published elsewhere (Rector and Michener 1989). This section summarizes the results and recommendations of that study, and presents parts of the discussion that might be of interest to a new user of the code.…”

Section: Cobra-sfs Cask Model Optimizationmentioning

confidence: 99%

COBRA-SFS: A thermal-hydraulic analysis code for spent fuel storage and transportation casks

Michener¹,

Rector²,

Cuta³

et al. 1995

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Printod inThis document presents a complete description of Cycle 2 of COBRA-SFS, and consists of three main parts. Part I describes the conservation equations, constitutive models, and solution methods used in the code. Part 11 presents the User Manual, with guidance on code applications, and complete input instructions. This part also includes a detailed description of the auxiliary code RADGEN, used to generate grey body view factors required as input for radiative heat transfer modeling in the code. Part I11 describes the code structure, platform dependent coding, and program hierarchy. Installation instructions are also given for the various platform versions of the code that are available.iii

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COBRA-SFS modifications and cask model optimization

Cited by 3 publications

References 6 publications

Modeling status and needs for temperature calculations within spent fuel disposal containers

Modeling status and needs for temperature calculations within spent fuel disposal containers

LLNL Input to SNL Report on the Composition of Available Data for Used Nuclear Fuel Storage and Transportation Analysis

COBRA-SFS: A thermal-hydraulic analysis code for spent fuel storage and transportation casks

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