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Benchmarking of finite element codes for radioactive material transportation packages

Description: The increased power of computers and computer codes makes the use of nonlinear dynamic finite element analyses attractive for use as a tool used in the design and certification of radioactive material transportation packages. For this analysis technique to be acceptable it must be demonstrated. The technique has the ability to accurately capture the response of the packages to accident environments required by the regulations. The best method of demonstrating this ability is via a series of benchmark analyses. In this paper three benchmark problems involving significant inelastic deformations will be discussed. One of the problems has been analyzed using many different finite element codes. The other two problems involve comparison of finite element calculations to the results form physical tests. The ability of the finite element method to accurately capture the response in these three problems indicates the method should be acceptable for radioactive material transportation package design and certification.
Date: October 1, 1996
Creator: Ammerman, D.J.
Partner: UNT Libraries Government Documents Department

Structural analysis in support of the waterborne transport of radioactive materials

Description: The safety of the transportation of radioactive materials by road and rail has been well studied and documented. However, the safety of waterborne transportation has received much less attention. Recent highly visible waterborne transportation campaigns have led to DOE and IAEA to focus attention on the safety of this transportation mode. In response, Sandia National Laboratories is conducting a program to establish a method to determine the safety of these shipments. As part of that program the mechanics involved in ship-to-ship collisions are being evaluated to determine the loadings imparted to radioactive material transportation packages during these collisions. This paper will report on the results of these evaluations.
Date: August 1, 1996
Creator: Ammerman, D.J.
Partner: UNT Libraries Government Documents Department

An assessment of simplified methods to determine damage from ship-to-ship collisions

Description: Sandia National Laboratories (SNL) is studying the safety of shipping, radioactive materials (RAM) by sea, the SeaRAM project (McConnell, et al. 1995), which is sponsored by the US Department of Energy (DOE). The project is concerned with the potential effects of ship collisions and fires on onboard RAM packages. Existing methodologies are being assessed to determine their adequacy to predict the effect of ship collisions and fires on RAM packages and to estimate whether or not a given accident might lead to a release of radioactivity. The eventual goal is to develop a set of validated methods, which have been checked by comparison with test data and/or detailed finite element analyses, for predicting the consequences of ship collisions and fires. These methods could then be used to provide input for overall risk assessments of RAM sea transport. The emphasis of this paper is on methods for predicting- effects of ship collisions.
Date: February 1, 1996
Creator: Parks, M.B. & Ammerman, D.J.
Partner: UNT Libraries Government Documents Department

Use of inelastic analysis to determine the response of packages to puncture accidents

Description: The accurate analytical determination of the response of radioactive material transportation packages to the hypothetical puncture accident requires inelastic analysis techniques. Use of this improved analysis method recudes the reliance on empirical and approximate methods to determine the safety for puncture accidents. This paper will discuss how inelastic analysis techniques can be used to determine the stresses, strains and deformations resulting from puncture accidents for thin skin materials with different backing materials. A method will be discussed to assure safety for all of these types of packages.
Date: August 1, 1996
Creator: Ammerman, D.J. & Ludwigsen, J.S.
Partner: UNT Libraries Government Documents Department

A comparison of methods for evaluating structure during ship collisions

Description: A comparison is provided of the results of various methods for evaluating structure during a ship-to-ship collision. The baseline vessel utilized in the analyses is a 67.4 meter in length displacement hull struck by an identical vessel traveling at speeds ranging from 10 to 30 knots. The structural response of the struck vessel and motion of both the struck and striking vessels are assessed by finite element analysis. These same results are then compared to predictions utilizing the {open_quotes}Tanker Structural Analysis for Minor Collisions{close_quotes} (TSAMC) Method, the Minorsky Method, the Haywood Collision Process, and comparison to full-scale tests. Consideration is given to the nature of structural deformation, absorbed energy, penetration, rigid body motion, and virtual mass affecting the hydrodynamic response. Insights are provided with regard to the calibration of the finite element model which was achievable through utilizing the more empirical analyses and the extent to which the finite element analysis is able to simulate the entire collision event. 7 refs., 8 figs., 4 tabs.
Date: October 1, 1996
Creator: Ammerman, D.J. & Daidola, J.C.
Partner: UNT Libraries Government Documents Department

Dynamic pulse buckling of cylindrical shells under axial impact: A benchmark study of 2D and 3D finite element calculations

Description: A series of tests investigating dynamic pulse buckling of a cylindrical shell under axial impact is compared to several 2D and 3D finite element simulations of the event. The purpose of the work is to investigate the performance of various analysis codes and element types on a problem which is applicable to radioactive material transport packages, and ultimately to develop a benchmark problem to qualify finite element analysis codes for the transport package design industry. During the pulse buckling tests, a buckle formed at each end of the cylinder, and one of the two buckles became unstable and collapsed. Numerical simulations of the test were performed using PRONTO, a Sandia developed transient dynamics analysis code, and ABAQUS/Explicit with both shell and continuum elements. The calculations are compared to the tests with respect to deformed shape and impact load history.
Date: April 1, 1995
Creator: Hoffman, E.L. & Ammerman, D.J.
Partner: UNT Libraries Government Documents Department

Testing of the structural evaluation test unit

Description: In the evaluation of the safety of radioactive material transportation it is important to consider the response of Type B packages to environments more severe than that prescribed by the hypothetical accident sequence in Title 10 Part 71 of the Code of Federal Regulations (NRC 1995). The impact event in this sequence is a 9-meter drop onto an essentially unyielding target, resulting in an impact velocity of 13.4 m/s. The behavior of 9 packages when subjected to impacts more severe than this is not well known. It is the purpose of this program to evaluate the structural response of a test package to these environments. Several types of structural response are considered. Of primary importance is the behavior of the package containment boundary, including the bolted closure and 0-rings. Other areas of concern are loss of shielding capability due to lead slump and the deceleration loading of package contents, that may cause damage to them. This type of information is essential for conducting accurate risk assessments on the transportation of radioactive materials. Currently very conservative estimates of the loss of package protection are used in these assessments. This paper will summarize the results of a regulatory impact test and three extra-regulatory impact tests on a sample package.
Date: December 1995
Creator: Ammerman, D. J. & Bobbe, J. G.
Partner: UNT Libraries Government Documents Department

Development on inelastic analysis acceptance criteria for radioactive material transportation packages

Description: The response of radioactive material transportation packages to mechanical accident loadings can be more accurately characterized by non-linear dynamic analysis than by the ``Equivalent dynamic`` static elastic analysis typically used in the design of these packages. This more accurate characterization of the response can lead to improved package safety and design efficiency. For non-linear dynamic analysis to become the preferred method of package design analysis, an acceptance criterion must be established that achieves an equivalent level of safety as the currently used criterion defined in NRC Regulatory Guide 7.6 (NRC 1978). Sandia National Laboratories has been conducting a study of possible acceptance criteria to meet this requirement. In this paper non-linear dynamic analysis acceptance criteria based on stress, strain, and strain-energy-density will be discussed. An example package design will be compared for each of the design criteria, including the approach of NRC Regulatory Guide 7.6.
Date: December 31, 1995
Creator: Ammerman, D.J. & Ludwigsen, J.S.
Partner: UNT Libraries Government Documents Department

Analytical determination of package response to severe impact

Description: One important part of radioactive material transport risk assessments is amount of release from packages in accidents more severe than design basis accident (US NRC 10CFR71 1995). In order to remove some of the conservatism from current risk assessments, an effort is ongoing to qualify the finite element method for predicting cask performance by comparing analytical results to test measurements of the Structural Evaluation Test Unit (SETU) cask. Comparisons of deformed shapes, strains, and accelerations were made for impact velocities of 13.4, 20.1, and 26.8 m/s (30, 45, and 60 mph). The 13.4 m/s impact corresponds to the regulatory 9 m (30 ft) free fall, and the others correspond to impacts with 2.25 and 4 times the kinetic energy of the regulatory impact. One other analysis at an impact velocity of 38.0 m/s (85 mph) or 8 times regulatory impact kinetic energy was also done.
Date: December 31, 1995
Creator: Ludwigsen, J. S. & Ammerman, D. J.
Partner: UNT Libraries Government Documents Department

Analysis of a ship-to-ship collision

Description: Sandia National Laboratories is involved in a safety assessment for the shipment of radioactive material by sea. One part of this study is investigation of the consequences of ship-to-ship collisions. This paper describes two sets of finite element analyses performed to assess the structural response of a small freighter and the loading imparted to radioactive material (RAM) packages during several postulated collision scenarios with another ship. The first series of analyses was performed to evaluate the amount of penetration of the freighter hull by a striking ship of various masses and initial velocities. Although these analyses included a representation of a single RAM package, the package was not impacted during the collision so forces on the package could not be computed. Therefore, a second series of analyses incorporating a representation of a row of seven packages was performed to ensure direct package impact by the striking ship. Average forces on a package were evaluated for several initial velocities and masses of the striking ship. In addition to. providing insight to ship and package response during a few postulated ship collisions scenarios, these analyses will be used to benchmark simpler ship collision models used in probabilistic risk assessment analyses.
Date: February 1, 1996
Creator: Porter, V.L. & Ammerman, D.J.
Partner: UNT Libraries Government Documents Department

Dynamic pulse buckling of cylindrical shells under axial impact: A comparison of 2D and 3D finite element calculations with experimental data

Description: A series of tests investigating dynamic pulse buckling of a cylindrical shell under axial impact is compared to several 2D and 3D finite element simulations of the event. The purpose of the work is to investigate the performance of various analysis codes and element types on a problem which is applicable to radioactive material transport packages, and ultimately to develop a benchmark problem to qualify finite element analysis codes for the transport package design industry. Four axial impact tests were performed on 4 in-diameter, 8 in-long, 304 L stainless steel cylinders with a 3/16 in wall thickness. The cylinders were struck by a 597 lb mass with an impact velocity ranging from 42.2 to 45.1 ft/sec. During the impact event, a buckle formed at each end of the cylinder, and one of the two buckles became unstable and collapsed. The instability occurred at the top of the cylinder in three tests and at the bottom in one test. Numerical simulations of the test were performed using the following codes and element types: PRONTO2D with axisymmetric four-node quadrilaterals; PRONTO3D with both four-node shells and eight-node hexahedrons; and ABAQUS/Explicit with axisymmetric two-node shells and four-node quadrilaterals, and 3D four-node shells and eight-node hexahedrons. All of the calculations are compared to the tests with respect to deformed shape and impact load history. As in the tests, the location of the instability is not consistent in all of the calculations. However, the calculations show good agreement with impact load measurements with the exception of an initial load spike which is proven to be the dynamic response of the load cell to the impact. Finally, the PRONIT02D calculation is compared to the tests with respect to strain and acceleration histories. Accelerometer data exhibited good qualitative agreement with the calculations. The strain comparisons show that measurements ...
Date: April 1995
Creator: Hoffman, E. L. & Ammerman, D. J.
Partner: UNT Libraries Government Documents Department

Use of inelastic design for radioactive material transportation packages

Description: There is much interest within the radioactive material transportation container design community in the use of inelastic analysis. In other industries where inelastic analysis is used in design there is typically an improved knowledge of the capacity of the structure and a more efficient use of material. This report describes the results of a program in which the incentives for inelastic analysis for radioactive material transport container design were investigated to determine if there are similar benefits. Detailed are the elastic and inelastic analyses of two containers subjected to impacts onto a rigid target following a thirty-foot free fall in end-on, side-on, and center-of-gravity- over-corner orientations.
Date: December 1, 1993
Creator: Heinstein, M. W. & Ammerman, D. J.
Partner: UNT Libraries Government Documents Department

Inelastic analysis acceptance criteria for radioactive material transportation containers

Description: The design criteria currently used in the design of radioactive material (RAM) transportation containers are taken from the ASME Boiler and Pressure Vessel Code (ASME, 1992). These load-based criteria are ideally suited for pressure vessels where the loading is quasistatic and all stresses are in equilibrium with externally applied loads. For impact events, the use of load-based criteria is less supportable. Impact events tend to be energy controlled, and thus, energy-based acceptance criteria would appear to be more appropriate. Determination of an ideal design criteria depends on what behavior is desired. Currently there is not a design criteria for inelastic analysis for RAM nation packages that is accepted by the regulatory agencies. This lack of acceptance criteria is one of the major factors in limiting the use of inelastic analysis. In this paper inelastic analysis acceptance criteria based on stress and strain-energy density will be compared for two stainless steel test units subjected to impacts onto an unyielding target. Two different material models are considered for the inelastic analysis, a bilinear fit of the stress-strain curve and a power law hardening model that very closely follows the stress-strain curve. It is the purpose of this paper to stimulate discussion and research into the area of strain-energy density based inelastic analysis acceptance criteria.
Date: June 1, 1993
Creator: Ammerman, D. J. & Ludwigsen, J. S.
Partner: UNT Libraries Government Documents Department

Regulatory and extra-regulatory testing to demonstrate radioactive material packaging safety

Description: Packages for the transportation of radioactive material must meet performance criteria to assure safety and environmental protection. The stringency of the performance criteria is based on the degree of hazard of the material being transported. Type B packages are used for transporting large quantities of radioisotopes (in terms of A{sub 2} quantities). These packages have the most stringent performance criteria. Material with less than an A{sub 2} quantity are transported in Type A packages. These packages have less stringent performance criteria. Transportation of LSA and SCO materials must be in {open_quotes}strong-tight{close_quotes} packages. The performance requirements for the latter packages are even less stringent. All of these package types provide a high level of safety for the material being transported. In this paper, regulatory tests that are used to demonstrate this safety will be described. The responses of various packages to these tests will be shown. In addition, the response of packages to extra-regulatory tests will be discussed. The results of these tests will be used to demonstrate the high level of safety provided to workers, the public, and the environment by packages used for the transportation of radioactive material.
Date: June 1, 1997
Creator: Ammerman, D.J.
Partner: UNT Libraries Government Documents Department

Testing in support of transportation of residues in the pipe overpack container

Description: The disposition of the large back-log of plutonium residues at the Rocky Flats Environmental Technology Site (Rocky Flats) will require interim storage and subsequent shipment to a waste repository. Current plants call for disposal at the Waste Isolation Pilot Plant (WIPP) and the transportation to WIPP in the TRUPACT-II. The transportation phase will require the residues to be packaged in a container that is more robust than a standard 55-gallon waste drum. Rocky Flats has designed the Pipe Overpack Container to meet this need. The tests described here were performed to qualify the Pipe Overpack Container as a waste container for shipment in the TRUPACT-II. Using a more robust container will assure the fissile materials in each container can not be mixed with the fissile material from the other containers and will provide criticality control. This will allow an increase in the payload of the TRUPACT-II from 325 fissile gram equivalents to 2,800 fissile gram equivalents.
Date: April 1, 1997
Creator: Ammerman, D.J.; Bobbe, J.G.; Arviso, M. & Bronowski, D.R.
Partner: UNT Libraries Government Documents Department

Testing in support of on-site storage of residues in the Pipe Overpack Container

Description: The disposition of the large back-log of plutonium residues at the Rocky Flats Environmental Technology Site (Rocky Flats) will require interim storage and subsequent shipment to a waste repository. Current plans call for disposal at the Waste Isolation Pilot Plant (WIPP) and the transportation to WIPP in the TRUPACT-II. The transportation phase will require the residues to be packaged in a container that is more robust than a standard 55-gallon waste drum. Rocky Flats has designed the Pipe Overpack Container to meet this need. It is desirable to use this same waste packaging for interim on-site storage in non-hardened buildings. To meet the safety concerns for this storage the Pipe Overpack Container has been subjected to a series of tests at Sandia National Laboratories in Albuquerque, New Mexico. In addition to the tests required to qualify the Pipe Overpack Container as a waste container for shipment in the TRUPACT-II several tests were performed solely for the purpose of qualifying the container for interim storage. This report will describe these tests and the packages response to the tests. 12 figs., 3 tabs.
Date: February 1, 1997
Creator: Ammerman, D.J.; Bobbe, J.G. & Arviso, M.
Partner: UNT Libraries Government Documents Department

A comparison of regulatory impacts to real target impacts

Description: The purpose of this paper is to discuss the relative severity of regulatory impacts onto an essentially rigid target to impacts at higher velocities onto real targets. For impacts onto the essentially rigid target all of the kinetic energy of the package is absorbed by deformation of the package. For impacts onto real targets the kinetic energy is absorbed by deformation of the target as well as by deformation of the package. The amount of kinetic energy absorbed by the target does not increase the severity of the impact.
Date: May 1, 1998
Creator: Ammerman, D.J.
Partner: UNT Libraries Government Documents Department

Analysis in support of storage of residues in the pipe overpack container

Description: The disposition of the large backlog of plutonium residues at the Rocky Flats Environmental Technology Site (Rocky Flats) will require interim storage and subsequent shipment to a waste repository. Current plans call for disposal at the Waste Isolation Pilot Plant (WIPP) and the transportation to WIPP in the TRUPACT-II. The transportation phase will require the residues to be packaged in a container that is more robust than a standard 55 gallon waste drum. Rocky Flats has designed the Pipe Overpack Container to meet this need. The potential for damage to this container during onsite storage in unhardened structures for several hypothetical accident scenarios has been addressed using finite element calculations. This report will describe the initial conditions and assumptions for these analyses and the predicted response of the container.
Date: April 1, 1998
Creator: Ludwigsen, J.S.; Ammerman, D.J. & Radloff, H.D.
Partner: UNT Libraries Government Documents Department

The effect of cargo on the crush loading of RAM transportation packages in ship collisions

Description: Recent intercontinental radioactive material shipping campaigns have focused public and regulatory attention on the safety of transport of this material by ocean-going vessels. One major concern is the response of the vessel and onboard radioactive material (RAM) packages during a severe ship-to-ship collision. These collisions occur at velocities less than the velocity obtained in the Type B package regulatory impact event and the bow of the striking ship is less rigid than the unyielding target used in those tests (Ammerman and Daidola, 1996). This implies that ship impact is not a credible scenario for damaging the radioactive material packages during ship collisions. It is possible, however, for these collisions to generate significant amounts of crush force by the bow of the impacting ship overrunning the package. It is the aim of this paper to determine an upper bound on the magnitude of this crush force taking into account the strength of the radioactive material carrying vessel and any other cargo that may be stowed in the same hold as the radioactive material.
Date: March 1, 1998
Creator: Radloff, H.D. & Ammerman, D.J.
Partner: UNT Libraries Government Documents Department

An analysis of parameters affecting slapdown of transportation packages

Description: Several parameters affecting the accelerations experienced by packages for the transport of nuclear material during eccentric impact are evaluated. Eccentric impact on one end of a cask causes rotation leading to secondary impact, referred to as slapdown, at the other end. In a slapdown event, the rotational acceleration during the primary impact can cause accelerations at the nose and tail which are greater than those during a side-on impact. Slapdown can also cause acceleration at the tail during the secondary impact to be more severe than at the nose during primary impact. Both of these effects are investigated for two casks geometries. Other parameters evaluated are the characteristics of impact limiters and friction between the impact limiter the impacted surface. Results were obtained using SLAPDOWN, a code which models the impact response of deformable bodies. 2 refs., 11 figs.
Date: January 1, 1991
Creator: Bergmann, V.L. & Ammerman, D.J.
Partner: UNT Libraries Government Documents Department

The development of a visualization tool for displaying analysis and test results

Description: The evaluation and certification of packages for transportation of radioactive materials is performed by analysis, testing, or a combination of both. Within the last few years, many transport packages that were certified have used a combination of analysis and testing. The ability to combine and display both kinds of data with interactive graphical tools allows a faster and more complete understanding of the response of the package to these environments. Sandia National Laboratories has developed an initial version of a visualization tool that allows the comparison and display of test and of analytical data as part of a Department of Energy-sponsored program to support advanced analytical techniques and test methodologies. The capability of the tool extends to both mechanical (structural) and thermal data.
Date: December 31, 1995
Creator: Uncapher, W.L.; Ammerman, D.J.; Ludwigsen, J.S.; Knight, R.D. & Wix, S.D.
Partner: UNT Libraries Government Documents Department

Computer-assisted comparison of analysis and test results in transportation experiments

Description: As a part of its ongoing research efforts, Sandia National Laboratories` Transportation Surety Center investigates the integrity of various containment methods for hazardous materials transport, subject to anomalous structural and thermal events such as free-fall impacts, collisions, and fires in both open and confined areas. Since it is not possible to conduct field experiments for every set of possible conditions under which an actual transportation accident might occur, accurate modeling methods must be developed which will yield reliable simulations of the effects of accident events under various scenarios. This requires computer software which is capable of assimilating and processing data from experiments performed as benchmarks, as well as data obtained from numerical models that simulate the experiment. Software tools which can present all of these results in a meaningful and useful way to the analyst are a critical aspect of this process. The purpose of this work is to provide software resources on a long term basis, and to ensure that the data visualization capabilities of the Center keep pace with advancing technology. This will provide leverage for its modeling and analysis abilities in a rapidly evolving hardware/software environment.
Date: May 10, 1998
Creator: Knight, R.D.; Ammerman, D.J. & Koski, J.A.
Partner: UNT Libraries Government Documents Department

SeaRAM: A DOE evaluation of maritime accident risk assessment data and methods

Description: The SeaRAM Program conducted for the US Department of Energy by Sandia National Laboratories has developed estimates of the frequencies of occurrence of ship fires and ship collisions, the fraction of all ship fires and ship collisions that might be sufficiently severe to challenge the integrity of a Type B spent fuel transportation cask, the magnitude of the radioactive source terms that might be released from a Type B spent fuel transportation cask due to loss of cask integrity, and the magnitude of the radiological consequences that might be caused by the radioactive release.
Date: March 1, 1998
Creator: Sprung, J.L.; Ammerman, D.J. & Koski, J.A.
Partner: UNT Libraries Government Documents Department

Testing and analysis to determine the shell thickness required to prevent puncture

Description: Type B radioactive material packages are required to withstand a hypothetical puncture accident of a free fall from a height of one meter onto a 15 cm diameter mild steel puncture probe. For many packages it is desirable to have this accident event not result in puncture or tearing of the outer shell of the package. The wall thickness necessary to prevent this has historically been determined by test or the use of empirical relations. This technique generally results in overly conservative designs, but the degree of conservatism is uncertain. The use of modem finite element codes to determine package response to puncture accidents can result in designs that are both safe and economical. The work reported in this paper is aimed at developing a method to analytically determine the wall thickness required to prevent puncture. For designers and regulators to have confidence in this analytical method, however, it must be benchmarked against test results. A series of tests has been conducted with differing shell thicknesses, shell materials of mild steel and stainless steel, and shell backing materials of lead, foam, and air. The results of these tests have been compared with pre-test analytical predictions of the response obtained from the nonlinear transient dynamic finite element program PRONTO-2D. From this comparison it can be seen that the finite element method can accurately predict the response of packages to puncture accidents. This implies that an analytical technique based on the finite element method can be used to design packages having known response and margin of safety against tearing of the outer shell. In addition, the analytical technique can accurately predict the deformed shape of the package following the test. This may be important for subsequent calculations, such as external dose and heat input during a thermal event.
Date: May 1, 1998
Creator: Ammerman, D.J.; Radloff, H.D. & Eifert, E.J.
Partner: UNT Libraries Government Documents Department