Bruno A. Autrusson

SPENT FUEL SABOTAGE TESTING: DEPLETED URANIUM OXIDE AEROSOL RESULTS.

Abstract This paper summarises a multinational, four phase, spent fuel sabotage test programme that quantifies aerosol particles produced when the products of a high energy density device (HEDD) interact with and explosively particulate test rodlets (∼20 cm long rods) that contain pellets of either surrogate materials or actual spent fuel. This programme provides source term data that are relevant to plausible sabotage attack scenarios in relation to spent fuel transport and storage casks, and associated risk assessments. Details and significant results are presented from three phase 3 tests performed using depleted UO2 (DUO2) pellets plus non-radioactive fission product dopants in surrogate spent fuel test rodlets. Measured aerosol results include: respirable fractions produced; particle size distributions; measurements of volatile fission product species enhanced sorption: enrichment factors onto respirable particles; and status on determination of the spent fuel ratio (SFR), needed for scaling studies. The DUO2 aerosol particle results are compared directly with similar phase 2 results from cerium oxide ceramic pellet and fission product dopant surrogate test rodlets. A status update is provided on preparations for the final phase 4 tests using rodlets containing actual PWR spent fuel. The source term data and programme design have been tailored to support and guide follow-on computer modelling of aerosol dispersal hazards and radiological consequence assessments. This spent fuel sabotage test programme was performed primarily at Sandia National Laboratories, with support provided by both the US Department of Energy and the Nuclear Regulatory Commission. This programme is strongly supported and coordinated by US and international programme participants in Germany and France, as part of the International Working Group for Sabotage Concerns of Transport and Storage Casks (WGSTSC).

Spent Fuel Sabotage Aerosol Test Program: FY 2005-06 Testing and Aerosol Data Summary

This multinational, multi-phase spent fuel sabotage test program is quantifying the aerosol particles produced when the products of a high energy density device (HEDD) interact with and explosively particulate test rodlets that contain pellets of either surrogate materials or actual spent fuel. This program has been underway for several years. This program provides source-term data that are relevant to some sabotage scenarios in relation to spent fuel transport and storage casks, and associated risk assessments. This document focuses on an updated description of the test program and test components for all work and plans made, or revised, primarily during FY 2005 and about the first two-thirds of FY 2006. It also serves as a program status report as of the end of May 2006. We provide details on the significant findings on aerosol results and observations from the recently completed Phase 2 surrogate material tests using cerium oxide ceramic pellets in test rodlets plus non-radioactive fission product dopants. Results include: respirable fractions produced; amounts, nuclide content, and produced particle size distributions and morphology; status on determination of the spent fuel ratio, SFR (the ratio of respirable particles from real spent fuel/respirables from surrogate spent fuel, measured under closely matched test conditions, in a contained test chamber); and, measurements of enhanced volatile fission product species sorption onto respirable particles. We discuss progress and results for the first three, recently performed Phase 3 tests using depleted uranium oxide, DUO{sub 2}, test rodlets. We will also review the status of preparations and the final Phase 4 tests in this program, using short rodlets containing actual spent fuel from U.S. PWR reactors, with both high- and lower-burnup fuel. These data plus testing results and design are tailored to support and guide, follow-on computer modeling of aerosol dispersal hazards and radiological consequence assessments. This spent fuel sabotage--aerosol test program, performed primarily at Sandia National Laboratories, with support provided by both the U.S. Department of Energy and the Nuclear Regulatory Commission, had significant inputs from, and is strongly supported and coordinated by both the U.S. and international program participants in Germany, France, and the U.K., as part of the international Working Group for Sabotage Concerns of Transport and Storage Casks, WGSTSC.

Study of the Dynamic Response of Large Scale Buildings Using Simplified Approaches

The dynamic response of large scale concrete buildings submitted to an explosion cannot always be obtained by means of classical FE analysis codes at reasonable costs. Indeed, the precision level required to predict efficiently the local failure of structural elements needs very fine meshes, which rapidly becomes unaffordable especially in the case of dynamics. The approach presented in this paper relies on a partitioning of the phenomena and their study by simplified methods: (1) The loading of the structure resulting from the detonation of an explosive charge is computed by a numerical implementation of semi-empirical formulas (Kinney and Graham, 1985, Baker et al., 1983); (2) The response of external walls elements, directly impacted by the aerial shock wave, is studied by a modal projection method, based on the use of analytical solutions from the thin plate theory; (3) Longitudinal propagation of the shock through the floors and walls of the building, including material and structural damping, is modeled by a 1D approach. This allows to determine finally whether the resistance limit of the constituting material is locally exceeded or not. Examples taken from a representative building study are presented in order to illustrate the approach.Copyright

International Working Group for Sabotage Concerns of Transport and Storage Casks

Abstract The International Working Group for Sabotage Concerns of Transport and Storage Casks (IWGSTSC), gathers multiple organisations from different countries (for US party Department of Energy, Nuclear Regulatory Commission, and Sandia National Laboratories; for German party Gesellschaft für Anlagen- und Reaktorsicherheit and Fraunhofer Institut; for the French party Institut de Radioprotection et de Sûreté Nucléaire). The goal of the IWGSTSC is to continue cooperation to improve the analytic capabilities, through information sharing and collaborative research and development plus modelling, to understand the potential adverse public health effects and environmental impacts of radiological sabotage directed at or associated with the transport and storage of civilian nuclear material or other civilian radioactive materials. The Parties may also undertake collaborative research and development in other areas of the physical protection of civilian nuclear materials or other radioactive materials. Since 2000, the IWGSTSC has conducted an extensive test programme for the assessment of the aerosol source term produced in the case of spent fuel transport sabotage by a high energy density device, after having examined several scenarios. The major goal of this programme is to produce an accurate estimate of the so called spent fuel ratio in the domain of respirable, aerosol particles produced. All the reports prepared by Sandia National Laboratories have precisely emphasised the important efforts they have made from the beginning and the amount of work already accomplished. In parallel, the International Atomic Energy Agency (IAEA), assisted by technical experts from different countries, has provided a draft document promised to become guidance for the security of radioactive or nuclear materials during transport. The IAEA document contains general guidance addressed to anyone who intends to implement or improve the security of material transports, but the text is, as of today, limited to rather general recommendations. Based on all the knowledge accumulated from past experiments and also based on the work carried out in Vienna at the IAEA, the IWGSTSC members have decided to work on the development of a method for the evaluation of the vulnerability and the source term. So for doing that, joint projects for the research, development, testing and evaluation of the consequences of the malevolent actions during transport are being pursued and are described in this paper.

Assessing consequences of nuclear material transport sabotage per use of armour piercing weapon

Abstract In order to predict the consequences of a sabotage act directed against a transport of nuclear material, the present paper is an attempt to put together some components of an approach dedicated to the assessment of the release produced when using a perforating or cutting device to spill out the content of the cask. The category of threat studied here is defined especially with regard to its objective: the objective of sabotage is to instantaneously create a radioactive source term capable of polluting a more or less important area including the vicinity of the target. This definition makes the difference with theft or diversion threats where the material is stolen and taken away from where it has been removed. The work accomplished and reported in this paper is in keeping with the general pattern of the multiyear programme of IRSN where the resistances of various casks to various threats are studied. This paper is structured in two parts. In the first part, the authors summarise as a whole the question of estimating the release after perforation and give a short review of past studies on the subject. All this work has motivated the development of an approach. The approach developed and used at IRSN is introduced by the statement of a generic problem. Then the authors identify all the influent parameters which need to be addressed. The most seducing aspect of the approach is the fact that it relies on only five parameters: the five parameters relate to the energy sources capable of moving the material from the inside to the outside, the cask resistance and the release mechanisms and physics. The authors have not included any numerical example in this paper due to the evident sensitivity of such material.

Behavior of Shipment Casks Under Explosive Loading

The behavior of the casks used for the shipment of nuclear material must be assessed for a set of various normal and accidental situations. The security of the casks must also be studied in the case of an explosion. To perform this study, the « Institut de Radioprotection et Surete Nucleaire » (IRSN) led a multi-years program since 1996, including numerical simulations and a set of 9 experimentations on reduced-scale mock-ups. Such a complete program is necessary to validate numerical models used to simulate the mechanical behavior of constitutive materials of the representative mock-up. On a counterpart, since numerous experimentations would be costly prohibitive, numerical simulations are used to find the worse conditions of loading considering the security of the casks. These conditions being established, different points are investigated (check of leaks, effects of surrounding casks, ...). The two last experimentations are devoted to specific aspects which could not be studied, in details, with numerical simulations because of the high number of degree of freedom or because the physical phenomena associated are not correctly modeled with computer codes yet.Copyright

Underwater Explosion in a Pool and Damage Assessment: A Global Approach From Far-Field to Close Range

The concern of this paper is the study of the effects of the detonation produced by an underwater explosive device. This work applies in particular to the study of some industrial pools, filled with water and a few meters deep. These pools are generally build so as to ensure a certain watertightness, this function being obtained for instance by the adjunction of an internal liner, a few millimeters thick and made of stainless steel. Here, we focus on the possible loss of this function both by the damage caused to concrete and the perforation of the liner. Those damages could be either due on one hand to the local deformations related to the global structure response and on the other hand to the local effects of the explosion. The first aspect has been investigated previously, using in particular the so-called “Method of Images (MOI)” (F. Delmaire-Sizes et al, 2001). The second aspect only occurs when the device is in a sufficiently close range so that the pressures produced by the detonation can cause volumetric damage into the materials. The starting point of this second phenomenon is investigated in the paper on the basis of a numerical model for concrete under high pressure and high strain rates (T. J. Holmquist, 1993). The second phenomenon comes in addition with the first one. An example is conducted showing how numerical simulations for the local analysis, coupling Eulerian and Lagrangian computations, complete the previous global analysis.Copyright

Behavior of a Building Under Explosive Loading

A simplified method developed for the analysis of the mechanical behavior of a building is presented. This method is based on modal analysis of the structure. It relies on a mathematical expansion of the dynamical equations of the movement on the eigenshapes of the structure. The time-space loading is defined by empiric formulae which take into account the weight of equivalent TNT, the distance between the explosive and the structure, and allows to describe the propagation of the shock wave on the structure. Three typical loadings are investigated: long distance explosions (blast loading), medium and near distance explosions. The results concerning the movement of the structure given by the simplified method will be compared to those obtained by a direct time integration method. Particularly, the convergence of the simplified method towards the direct time integration method will be investigated in terms of displacements and stresses versus the explosive-structure distance. This method allows to identify the eigenshapes and eigenvalues of the structure which are important to be taken into account to predict the dynamical response of the building. This method is used as a pre-study (elastic mechanics) i.e. as a first step of a detailed dynamical analysis.Copyright