Radioactive Material Transport Packages Research Articles

Framework for dynamic analysis of radioactive material transport packages under accident drop conditions

Radioactive material transport packages for certain forms of radioactive materials are designed to withstand a 9-meter accident drop onto an essentially rigid surface in accordance with the IAEA regulations SSR-6. This study presents a framework for dynamic analysis of transport packages under accident drop and impact conditions. To evaluate structural behavior and performance of the transport packages with large deformation occurring in a very short duration, material models incorporated in the dynamic analysis framework are established with four key aspects: 1) true stress and strain are used to describe characteristics of large deformation of materials; 2) effect of strain rate is included to reveal dynamic response of materials to high-energy impact loads; 3) material constitutive models are established to capture realistic mechanical behaviour of materials under highly triaxial stress states; and 4) stress triaxiality-dependent damage and fracture criteria of materials are incorporated to limit the plastic deformation to material fracture and to safeguard the containment boundary of the Dry Storage Container (DSC) that contains the used (i.e., irradiated) fuel or other forms of radioactive materials. Critical material and model parameters and properties associated with the material constitutive models, true stress-strain relationships, strain rate effect, and damage and fracture criteria are appropriately determined based on experimental results or theoretically derived based on observed material behavior in elementary stress states. The implementation of the proposed analysis framework is demonstrated by a case study for a Type B(U) transport package, with results to predict the maximum true plastic strain, strain rate, and damage condition of the materials of the package. Since the proposed analysis framework is comprehensive enough to cover necessary aspects to complete an advanced analysis, and the critical material and model parameters are properly determined within this framework that can be readily implemented, the proposed analysis framework is capable of addressing high-energy accident drop scenarios and impact conditions of radioactive material transport packages and containers to meet the nuclear licensing requirements.

Performance of metal and polymeric O-ring seals during beyond-design-basis thermal conditions

This paper summarizes the small scale thermal exposure test results of the performance of metallic and polymeric O-ring seals typically used in radioactive material transportation packages. Five different O-ring materials were evaluated: Inconel/silver, ethylene-propylene diene monomer (EPDM), polytetrafluoroethylene (PTFE), silicone, butyl, and Viton. The overall objective of this study is to provide test data and insights to the performance of these O-ring seals when exposed to beyond-design-basis temperature conditions due to a severe fire. Tests were conducted using a small-scale stainless steel pressure vessel pressurized with helium to 2 bar or 5 bar at room temperature. The vessel was then heated in an electric furnace to temperatures up to 900 °C for a pre-determined period (typically 8 h–9 h). The pressure drop technique was used to determine if leakage occurred during thermal exposure. Out of a total of 46 tests performed, leakage (loss of vessel pressure) was detected in 13 tests.

Brand new fire test facilities at ‘BAM Test Site Technical Safety’

AbstractFire testing is an essential part of the hypothetical, cumulative mechanical and thermal accident test conditions that shall guarantee package safety in severe accidents. Not only for radioactive material transport packages but also for other containments of dangerous goods, international standards require specific thermal load specifications. Following the guideline ‘Safety in technology and chemistry’ BAM, as a scientific and technical German federal government institute, operates a 12 km2 large open air test facility for experimental investigations of dangerous goods and their containments. On an area beside the well-known 200-ton drop test facility, BAM has put into operation a new fire test facility. This facility provides two fire test stands that utilise liquid propane as fuel from a central, earth-covered 60 m3 LPG storage tank. From that storage the propane is pumped via pipelines to the test stands where the gas is released from nozzles, and ignited by ignition burners. The fire exposure...

Recent assessments in USA of spent fuel packages exposed to severe thermal environments different from regulatory standards

AbstractThe regulatory driven design of radioactive material transportation packages leads package vendors to perform analyses that demonstrate the ability of packages to meet the regulatory requirements. For risk assessment and communication, the analysis of package response to thermal environments that are more severe than those described in the regulations is required. In general, experimental and analytical assessments of casks exposed to thermal insults other than the regulatory environment are performed in the USA by the Department of Energy national laboratories. This paper provides a brief summary of some recent thermal analyses of spent fuel transportation packages exposed to thermal environments different from regulatory standards. The analyses were performed by Sandia National Laboratories under several different projects for multiple customers. These analyses examined the response of spent fuel packages exposed to severe thermal environments different from the regulatory hypothetical accident ...

Recent assessments in USA of Type B packages to impacts beyond regulatory package test standards

The regulatory driven design of radioactive material transportation packages leads packaging vendors to perform analyses that demonstrate the package's ability to meet the regulatory requirements. However, for risk assessment and communication, the response of packages to impacts that are more severe than the regulatory impact is required. Traditionally, in the USA, the task of performing assessments of package response to impacts more severe than the regulatory ones has been performed by the US Department of Energy (DOE) national laboratories. These assessments have been both experimental and analytical. This paper provides a brief history of extraregulatory package impacts and then focuses on recent analyses performed by Sandia National Laboratories for the US Nuclear Regulatory Commission (NRC) and the US DOE. The analyses have been primarily in support of two large studies: 'Re-examination of spent fuel shipment risk estimates' and 'Package performance study'. The first of these examined the response of four generic spent fuel casks to impacts onto rigid targets at speeds up to 53˙6 m s–1 (120 mph). The second examined the response of two certified spent fuel cask designs to impacts up to 33˙5 m s–1 (75 mph). Analyses have been performed for closure end impacts, closure end CG over corner impacts and side-on impacts. The analyses and testing of packages to beyond regulatory impact standards have shown that the packages have a considerable margin of safety against release of radioactive material. This fact reinforces the adequacy of the packaging requirements of the US NRC and International Atomic Energy Agency (IAEA) and the methods currently used to certify that spent fuel casks meet these requirements.

Scale model impact limiter in type assessment of radioactive material transport packages

AbstractIn Germany, the Federal Institute for Materials Research and Testing (BAM) is the competent authority for the mechanical and thermal design safety assessment of transport packages for radioactive material according to IAEA regulations. The combination of experimental and numerical safety proof forms the basis for a state of the art evaluation concept. Reduced scale models are often used in experimental investigation for design assessment of transport packages corresponding to IAEA regulations. This approach is limited by the fact that a reduced scale model cask can show different behaviours from a full scale cask. The paper focuses on the peculiarities of wood filled impact limiter of reduced scale models. General comments on drop testing with reduced scale models are given, and the relevant paragraphs of the IAEA regulations and Advisory Material are analysed. Possible factors likely to influence the energy absorbing capacity of wood filled impact limiting devices are identified on the basis of s...

Benchmark of a Fast-Running Computational Tool for Analysis of Massive Radioactive Material Packages in Fire Environments

Federal regulations (10CFR71) require radioactive material transport packages to safely withstand a 30min fully engulfing fire. The three-dimensional Container Analysis Fire Environment (CAFE-3D) computer code was developed at Sandia National Laboratories to simulate the response of massive packages to large fires for design and risk studies. These studies require rapid and accurate estimates of the package temperature distribution for a variety of package designs and fire environments. To meet these needs CAFE-3D links a finite element model that calculates the package response to the Isis-3D CFD fire model. ISIS-3D combines computational fluid dynamics with reaction chemistry and thermal radiation models to rapidly estimate the heat transfer from a fire. In the current work, parameters used in the fire model were determined. Simulations were then performed of a test that modeled the conditions of a truck-sized nuclear waste package in a regulatory fire under light wind conditions. CAFE-3D underestimated the ability of the wind to tilt the fire and deliver oxygen to the region above the fuel pool. However, it accurately and rapidly estimated the total heat transfer to the test object. CAFE-3D will become a more useful tool for estimating the response of transport packages to large fires once it has been benchmarked against a larger range of fire conditions.

Test Facilities for Radioactive Materials Transport Packagings (BAM, Germany)

The test facilities, test and safety assessment methods available at the Bundesanstalt für Materialforschung und –prüfung (Federal Institute for Materials Research and Testing), Germany, for testing radioactive materials transport packages are described in this paper.

Test Facilities for Radioactive Material Transport Packages at HH-IFIN (Romania)

Abstract This paper describes the test facilities available at the ‘Horia Hulubei’ National Institute for Physics and Nuclear Engineering, Romania, for radioactive material transport and storage packages.

Test Facilities for Radioactive Materials Transport Packages at Sandia National Laboratories, USA

AbstractCompliance with regulatory requirements for normal and hypothetical accident environments can be demonstrated by testing packages to transport radioactive materials. A comprehensive testing capability has been developed by the US Department of Energy at Sandia National Laboratories to simulate the required test conditions and provide response data. Several of the major test facilities available to support testing of radioactive material packages are described in this paper.

Test Facilities for Radioactive Material Transport Packages (AEA Technology plc, Winfrith, UK)

Transport containers for radioactive materials are tested to demonstrate compliance with national and international standards. Transport package design, testing, assessment and approval requires a wide range of skills and facilities. The comprehensive capability of AEA Technology in these areas is described. The facilities described include drop-test cranes and targets (up to 700 tonne); pool fires, furnaces and rigs for thermal tests, including heat dissipation on prototype flasks; shielding facilities; criticality simulations and leak test techniques. These are illustrated with photographs demonstrating the comprehensive nature of package testing services supplied to customers.

Test Facilities for Radioactive Material Transport Packages (LNE, Paris, France)

This paper describes the test facilities at Laboratoire National d'Essais (LNE) for radioactive material transport packages covering IP, Type A and Type B packages.

Test Facilities for Radioactive Material Transport Packages (Croft Associates, UK)

A brief summary of the package test facilities provided by Croft Associates is given.

Crush Loadings to Radioactive Material Transport Packages During Ship Collisions

Accident-resistant Type B packages are used to transport radioactive materials such as spent fuel and vitrified high level waste in all surface modes, in accordance with national and international regulations. As with other modes, a sea-goingconveyance (vessel) carrying radioactive material (RAM) may be involved in a collision accident. If the vessel is struck byanother commercial vessel with sufficient tonnage and velocity, the RAM package may be impacted by the penetrating bow ofthe striking ship. The impact on the RAM package by the bow is less damaging to the package than the regulatory 9 m droptest. This is because the velocity is always lower and the bow always less rigid than the essentially unyielding target requiredfor the drop test. Thus, the only remaining mechanism for gross damage to the package is crush loading. For the package to becrushed, forces must act on two opposing sides. In this paper, the bow of the impacting ship is assumed to be able to impartan infinite force to one side of the package. The opposing force is supplied by the hull of the struck ship on the side away fromthe collision. Resistance of this hull to penetration by the package determines the maximum magnitude of the crush force. Workdescribed in this paper is aimed at determining an upper bound for this force.

Application of Laboratory Fracture Toughness Measurements to Ensure Fracture Resistance of Transport Packages

Applying laboratory fracture toughness measurements to ensure the fracture resistance of radioactive material transport packages is critical to a fracture mechanics based design. Unfortunately, the dependence of the fracture toughness of many materials on temperature, loading rate, and specimen size complicates the application of laboratory results to the evaluation of full-scale transport package behaviour. A review of previous research related to small specimen test results and a summary of the methods which have been proposed to ensure that transport packages will not fail by brittle fracture is presented. A single specimen elevated rate fracture toughness testing technique is presented as a practical means of quantifying the fracture toughness of samples which can be taken from larger structures. This technique has been successfully applied to the testing of ductile iron (DI). A method of quantifying constraint effects will allow the results from small specimens (such as those machined from corings removed from each package during serial production) to be used directly to ensure the fracture safety of each individual full-scale unit.

Benchmark study of two- and three-dimensional, finite element calculations, simulating dynamic pulse buckling tests of cylindrical shells under axial impact

Abstract A series of tests investigating dynamic pulse buckling of a cylindrical shell under axial impact is compared with several finite element simulations of the event. The purpose of the study is to compare the performance of the various analysis codes and element types with respect to 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. Although the finite element codes used in this study utilize similar element technology, there are differences in the numerical solutions. Furthermore, this study demonstrates that experiments—which are typically accepted as the “correct” answer—can have multiple results because of design sensitivities. Multiplicity of experimental results suggests that experiments performed for numerical benchmarks should first be numerically evaluated for such sensitivities.

Test Facilities for Radioactive Material Transport Packages (Southwest Research Institute, USA)

AbstractThe facilities available at the Southwest Research Institute for testing radioactive materials transport packages are described.

Test Facilities for Radioactive Material Transport Packages (Australia)

Test facilities at the Australian Nuclear Science and Technology Organisation, for Type A and Type B packages for the transport of radioactive materials are very briefly described.

Testing Facilities for Radioactive Material Transport Packages (Croft Associates, UK)

Testing Facilities for Radioactive Material Transport Packages (Croft Associates, UK)

Testing Facilities for Radioactive Materials Transport Packages (Association of American Railroads, USA)

AbstractThe Transport Test Center of the American Railroads Association has extensive test facilities which can be adapted to undertake tests on packages for the transport of radioactive materials.