The advent of the nuclear renaissance gives rise to a concern for the effective design of nuclear fuel cycle systems that are safe, secure, nonproliferating and cost-effective. We propose to integrate the monitoring of the four major factors of nuclear facilities by focusing on the interactions between Safeguards, Operations, Security, and Safety (SOSS). We proposed to develop a framework that monitors process information continuously and can demonstrate the ability to enhance safety, operations, security, and safeguards by measuring and reducing relevant SOSS risks, thus ensuring the safe and legitimate use of the nuclear fuel cycle facility. A real-time comparison between expected and observed operations provides the foundation for the calculation of SOSS risk. The automation of new nuclear facilities requiring minimal manual operation provides an opportunity to utilize the abundance of process information for monitoring SOSS risk. A framework that monitors process information continuously can lead to greater transparency of nuclear fuel cycle activities and can demonstrate the ability to enhance the safety, operations, security and safeguards associated with the functioning of the nuclear fuel cycle facility. Sandia National Laboratories (SNL) has developed a risk algorithm for safeguards and is in the process of demonstrating the ability to monitor operational signals in real-time though a cooperative research project with the Japan Atomic Energy Agency (JAEA). The risk algorithms for safety, operations and security are under development. The next stage of this work will be to integrate the four algorithms into a single framework.
This paper summarizes the results of a Phenomena Identification and Ranking Table (PIRT) exercise performed for nuclear power plant (NPP) fire modeling applications conducted on behalf of the U.S. Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research (RES). A PIRT exercise is a formalized, facilitated expert elicitation process. In this case, the expert panel was comprised of seven international fire science experts and was facilitated by Sandia National Laboratories (SNL). The objective of a PIRT exercise is to identify key phenomena associated with the intended application and to then rank the importance and current state of knowledge of each identified phenomenon. One intent of this process is to provide input into the process of identifying and prioritizing future research efforts. In practice, the panel considered a series of specific fire scenarios based on scenarios typically considered in NPP applications. Each scenario includes a defined figure of merit; that is, a specific goal to be achieved in analyzing the scenario through the application of fire modeling tools. The panel identifies any and all phenomena relevant to a fire modeling-based analysis for the figure of merit. Each phenomenon is ranked relative to its importance to the fire model outcome and then further ranked against the existing state of knowledge and adequacy of existing modeling tools to predict that phenomenon. The PIRT panel covered several fire scenarios and identified a number of areas potentially in need of further fire modeling improvements. The paper summarizes the results of the ranking exercise.
One source of concern in the nuclear power community is associated with performing PRAs on the passive systems used in Advanced Light Water Reactors. Passive systems rely on physical phenomena in order to perform safety actions. This leads to questions about how one should model the reliability of the system, such as how one should model the uncertainty in physical parameters that define the operational characteristics of the passive system and how to determine the degradation and failure characteristics of a system. Hierarchical Bayesian techniques provide a means for assessing the types of problems presented by passive systems. They allow the analyst to collect multiple types of data, including expert judgment and historical data from different sources and then combine them in one analysis. The importance of this feature is that it allows an analyst to perform a mathematically consistent PRA without large amounts of data for the specific system under scrutiny. As data become available, they are incorporated into the analysis using Bayes' rule. As the dataset becomes large, the data dominate the analysis. A study is performed whereby data are collected from a set of resistors in a corrosive environment. A model is created that related the environmental conditions of the sensors being used to the performance of the sensors. Prior distributions are then proposed for the uncertain parameters. Both longitudinal and failure data are recorded for the sensors. These data are then used to update the model and obtain the posterior distributions related to the uncertain parameters.
The drift-shadow effect describes capillary diversion of water flow around a drift or cavity in porous or fractured rock, resulting in lower water flux directly beneath the cavity. This paper presents computational simulations of drift-shadow experiments using dual-permeability models, similar to the models used for performance assessment analyses of flow and seepage in unsaturated fractured tuff at Yucca Mountain. Results show that the dual-penneability models capture the salient trends and behavior observed in the experiments, but constitutive relations (e.g., fracture capillary-pressure curves) can significantly affect the simulated results. An evaluation of different meshes showed that at the grid refinement used, a comparison between orthogonal and unstructured meshes did not result in large differences.
Ceramic samples of Pb0.99La0.01 (Zr 0.91Ti0.09)O3 were studied by dielectric and time-of-flight neutron diffraction measurements at 300 and 250 K versus pressure. Isothermal dielectric data (300/250 K) suggest structural transitions with onsets near 0.35/0.37 GPa, respectively, for increasing pressure. On pressure release, only the 300K transition occurs (0.10 GPa; none indicated at 250 K). Diffraction data at 300 K show the sample has the R3c structure, remaining in that phase cooling to 250 K. Pressure increase (either 300 or 250 K) above 0.3 GPa yields a Pnma-like (AO) phase (two other prominent peaks in the spectra suggest a possible incommensurate cell). Temperature/pressure excursions show considerable phase hysteresis.
American Nuclear Society - 12th International High-Level Radioactive Waste Management Conference 2008
Sevougian, S.D.; Behie, Alda; Chipman, Veraun; Gross, Michael B.; Mehta, Sunil; Statham, William
The representation of disruptive events (seismic and igneous events) and early failures of waste packages and drip shields in the 2008 total system performance assessment (TSPA) for the proposed high-level radioactive waste repository at Yucca Mountain, Nevada is described, in the context of the 2008 TSPA, disruptive events and early failures are treated as phenomena that occur randomly (e.g., the time of a seismic event) and also have properties that are random (e.g., the peak ground velocity associated with a seismic event). Specifically the following potential disruptions are considered: (i) early failure of individual drip shields, (ii) early failure of individual waste packages, (iii) igneous intrusion events that result in the filling of the waste disposal drifts with magma, (iv) volcanic eruption events that result in the dispersal of waste into the atmosphere, (v) seismic events that damage waste packages and drip shields as a result of strong vibratory ground motion, and (vi) seismic events that damage waste packages and drip shields as a result of shear displacement along a fault. Example annual dose results are shown for the two most risk-significant events: strong seismic ground motion and igneous intrusion.
The development of separation distances for hydrogen facilities can be determined in several ways. A conservative approach is to use the worst possible accidents in terms of consequences. Such accidents may be of very low frequency and would likely never occur. Although this approach bounds separation distances, the resulting distances are generally prohibitive. The current separation distances in hydrogen codes and standards do not reflect this approach. An alternative deterministic approach that is often utilized by standards development organizations and allowed under some regulations is to select accident scenarios that are more probable but do not provide bounding consequences. In this approach, expert opinion is generally used to select the accidents used as the basis for the prescribed separation distances.
Proceedings - 2008 International Symposium on Microelectronics, IMAPS 2008
Knudson, R.T.; Barner, Greg; Smith, Frank; Zawicki, Larry; Peterson, Ken
Full tape thickness features (FTTF) using conductors, high K and low K dielectrics, sacrificial volume materials, and magnetic materials are useful as both technically and cost-effective approaches to multiple needs in laminate microelectronic and microsystem structures. Lowering resistance in conductor traces of all kinds, raising Q-factors in coils, and enhancing EMI shielding in RF desingns are a few of the modern needs. By filling with suitable dielectric compositions one can deliver embedded capacitors with an appropriate balance between mechanical compatibility and safety factor for fabrication. Similar techniques could be applied to magnetic materials without wasteful manufacturing processes when the magnetic material is a small fraction of the overall circuit area. Finally, to open the technology of unfilled volumes for radio frequency performance as well as microfluidics and mixed cofired material applications, the full tape thickness implementation of sacrificial volume materials is also considered. We discuss implementations of FTTF structures and discuss technical problems and the promise such structures hold for the future.
A series of modal tests were performed in order to validate a finite element model of a complex aerospace structure. Data was measured using various excitation methods in order to extract clean modes and damping values for a lightly damped system. Model validation was performed for one subassembly as well as for the full assembly in order to pinpoint the areas of the model that required updating and to better ascertain the quality of the joint models connecting the various components and subassemblies. After model updates were completed, using the measured modal data, the model was validated using frequency response functions (FRFs) as the independent validation metric. Test and model FRFs were compared to determine the validity of the finite element model.
Optical tweezers has become a powerful and common tool for sensitive determination of electrostatic interactions between colloidal particles. Two optical trapping based techniques, blinking tweezers and direct force measurements, have become increasingly prevalent in investigations of interparticle potentials. The blinking laser tweezers method repeatedly catches and releases a pair of particles to gather physical statistics of particle trajectories. Statistical analysis is used to determine drift velocities, diffusion coefficients, and ultimately colloidal forces as a function of the center-center separation of the particles. Direct force measurements monitor the position of a particle relative to the center of an optical trap as the separation distance between two continuously trapped particles is gradually decreased. As the particles near each other, the displacement from the trap center for each particle increases proportional to the inter-particle force. Although commonly employed in the investigation of interactions of colloidal particles, there exists no direct comparison of these experimental methods in the literature. In this study, an experimental apparatus was developed capable of performing both methods and is used to quantify electrostatic potentials between two sizes of polystyrene particles in an AOT hexadecane solution. Comparisons are drawn between the experiments conducted using the two measurement techniques, theory, and existing literature. Forces are quantified on the femto-Newton scale and results agree well with literature values.