In March 2005, the United States Coast Guard requested that Sandia National Laboratories provide a technical review and evaluation of the appropriateness and completeness of models, assumptions, analyses, and risk management options presented in the Cabrillo Port LNG Deepwater Port Independent Risk Assessment-Revision 1 (Cabrillo Port IRA). The goal of Sandia's technical evaluation of the Cabrillo Port IRA was to assist the Coast Guard in ensuring that the hazards to the public and property from a potential LNG spill during transfer, storage, and regasification operations were appropriately evaluated and estimated. Sandia was asked to review and evaluate the Cabrillo Port IRA results relative to the risk and safety analysis framework developed in the recent Sandia report, ''Guidance on Risk Analysis and Safety Implications of a Large Liquefied Natural Gas (LNG) Spill over Water''. That report provides a framework for assessing hazards and identifying approaches to minimize the consequences to people and property from an LNG spill over water. This report summarizes the results of the Sandia review of the Cabrillo Port IRA and supporting analyses. Based on our initial review, additional threat and hazard analyses, consequence modeling, and process safety considerations were suggested. The additional analyses recommended were conducted by the Cabrillo Port IRA authors in cooperation with Sandia and a technical review panel composed of representatives from the Coast Guard and the California State Lands Commission. The results from the additional analyses improved the understanding and confidence in the potential hazards and consequences to people and property from the proposed Cabrillo Port LNG Deepwater Port Project. The results of the Sandia review, the additional analyses and evaluations conducted, and the resolutions of suggested changes for inclusion in a final Cabrillo Port IRA are summarized in this report.
While recognized standards exist for the systematic safety analysis of potential spills or releases from LNG (Liquefied Natural Gas) storage terminals and facilities on land, no equivalent set of standards or guidance exists for the evaluation of the safety or consequences from LNG spills over water. Heightened security awareness and energy surety issues have increased industry's and the public's attention to these activities. The report reviews several existing studies of LNG spills with respect to their assumptions, inputs, models, and experimental data. Based on this review and further analysis, the report provides guidance on the appropriateness of models, assumptions, and risk management to address public safety and property relative to a potential LNG spill over water.
Fires in aircraft engine nacelles must be rapidly suppressed to avoid loss of life and property. The design of new and retrofit suppression systems has become significantly more challenging due to the ban on production of Halon 1301 for environmental concerns. Since fire dynamics and the transport of suppressants within the nacelle are both largely determined by the available air flow, efforts to define systems using less effective suppressants greatly benefit from characterization of nacelle air flow fields. A combined experimental and computational study of nacelle air flow therefore has been initiated. Calculations have been performed using both CFD-ACE (a Computational Fluid Dynamics (CFD) model with a body-fitted coordinate grid) and WLCAN (a CFD-based fire field model with a Cartesian ''brick'' shaped grid). The flow conditions examined in this study correspond to the same Reynolds number as test data from the full-scale nacelle simulator at the 46 Test Wing. Pre-test simulations of a quarter-scale test fixture were performed using CFD-ACE and WLCAN prior to fabrication. Based on these pre-test simulations, a quarter-scale test fixture was designed and fabricated for the purpose of obtaining spatially-resolved measurements of velocity and turbulence intensity in a smooth nacelle. Post-test calculations have been performed for the conditions of the experiment and compared with experimental results obtained from the quarter-scale test fixture. In addition, several different simulations were performed to assess the sensitivity of the predictions to the grid size, to the turbulence models, and to the use of wall functions. In general, the velocity predictions show very good agreement with the data in the center of the channel but deviate near the walls. The turbulence intensity results tend to amplify the differences in velocity, although most of the trends are in agreement. In addition, there were some differences between WLCAN and CFD-ACE results in the angled wall regions due to the Cartesian grid structure used by the WLCAN code. Also, the experimental data tended t o show poorer resolution near the walls of the transition ducts. The increased uncertainty in the data highlights some of the challenges in getting data near the walls due to the low signal to noise ratio. Overall, this effort provided a benchmark case for both the WLCAN and CFD-ACE codes for the application of interest.
As part of the full scale fuel fire experimental program, a series of JP-8 pool fire experiments with a large cylindrical calorimeter (3.66 m diameter), representing a C-141 aircraft fuselage, at the lee end of the fuel pool were performed at Naval Air Warfare Center, Weapons Division (NAWCWPNS). The series was designed to support Weapon System Safety Assessment (WSSA) needs by addressing the case of a transport aircraft subjected to a large fuel fire. The data collected from this mock series will allow for characterization of the fire environment via a survivable test fixture. This characterization will provide important background information for a future test series utilizing the same fuel pool with an actual C-141 aircraft in place of the cylindrical calorimeter.
A gridless technique for the solution of the integral form of the radiative heat flux equation for emitting and absorbing media is presented. Treatment of non-uniform absorptivity and gray boundaries is included. As part of this work, the authors have developed fast multipole techniques for extracting radiative heat flux quantities from the temperature fields of one-dimensional and three-dimensional geometries. Example calculations include those for one-dimensional radiative heat transfer through multiple flame sheets, a three-dimensional enclosure with black walls, and an axisymmetric enclosure with black walls.
Smoke is known to cause electrical equipment failure, but the likelihood of immediate failure during a fire is unknown. Traditional failure assessment techniques measure the density of ionic contaminants deposited on surfaces to determine the need for cleaning or replacement of electronic equipment exposed to smoke. Such techniques focus on long-term effects, such as corrosion, but do not address the immediate effects of the fire. This document reports the results of tests on the immediate effects of smoke on electronic equipment. Various circuits and components were exposed to smoke from different fields in a static smoke exposure chamber and were monitored throughout the exposure. Electrically, the loss of insulation resistance was the most important change caused by smoke. For direct current circuits, soot collected on high-voltage surfaces sometimes formed semi-conductive soot bridges that shorted the circuit. For high voltage alternating current circuits, the smoke also tended to increase the likelihood of arcing, but did not accumulate on the surfaces. Static random access memory chips failed for high levels of smoke, but hard disk drives did not. High humidity increased the conductive properties of the smoke. The conductivity does not increase linearly with smoke density as first proposed; however, it does increase with quantity. The data can be used to give a rough estimate of the amount of smoke that will cause failures in CMOS memory chips, dc and ac circuits. Comparisons of this data to other fire tests can be made through the optical and mass density measurements of the smoke.
A spray-suppression model that captures the effects of liquid suppressant on a turbulent combusting flow is developed and applied to a turbulent diffusion flame with water spray suppression. The spray submodel is based on a stochastic separated flow approach that accounts for the transport and evaporation of liquid droplets. Flame extinguishment is accounted for by using a perfectly stirred reactor (PSR) submodel of turbulent combustion. PSR pre-calculations of flame extinction times are determined using CHEMKIN and are compared to local turbulent time scales of the flow to determine if local flame extinguishment has occurred. The PSR flame extinguishment and spray submodels are incorporated into Sandia's flow fire simulation code, VULCAN, and cases are run for the water spray suppression studies of McCaffrey for turbulent hydrogen-air jet diffusion flames. Predictions of flame temperature decrease and suppression efficiency are compared to experimental data as a function of water mass loading using three assumed values of drop sizes. The results show that the suppression efficiency is highly dependent on the initial droplet size for a given mass loading. A predicted optimal suppression efficiency was observed for the smallest class of droplets while the larger drops show increasing suppression efficiency with increasing mass loading for the range of mass loadings considered. Qualitative agreement to the experiment of suppression efficiency is encouraging, however quantitative agreement is limited due to the uncertainties in the boundary conditions of the experimental data for the water spray.
Scattering to extinction cross-section ratios, {rho}{sub se} were measured using the NIST Large Agglomerate Optics Facility for soot produced from ethene and acetylene laminar diffusion flames. Measurements were performed using light sources at 543.5 nm, 632.8 nm and 856 nm. The average scattering to extinction cross-section ratios for these wavelengths are equal to 0.246, 0.196, and 0.196 for ethene and 0.316, 0.230, and 0.239 for acetylene. The 856 nm measurements represent the longest wavelength for which accurate scattering measurements have been performed for soot. The size distribution and fractal properties of the two soots were determined to assess the effects of limited acceptance angle range, finite size of the sensor, and departure from cosine response on the uncertainty in the measurement of {rho}{sub se} The expanded relative uncertainty (95% confidence level) was found to be {+-}6% at the two visible wavelengths and {+-}8% at 856 nm. Both the magnitude and wavelength dependence of {rho}{sub se} for the present experiments are significantly different from those reported by Krishnan et al. for overfire soot produced using a turbulent flame. The results are compared with the predictions of fractal optics.