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Houston, TX, United States

Barrett A.M.,Abs Consulting | Adams P.J.,Carnegie Mellon University
Risk Analysis | Year: 2011

We develop and apply an integrated modeling system to estimate fatalities from intentional release of 17 tons of chlorine from a tank truck in a generic urban area. A public response model specifies locations and actions of the populace. A chemical source term model predicts initial characteristics of the chlorine vapor and aerosol cloud. An atmospheric dispersion model predicts cloud spreading and movement. A building air exchange model simulates movement of chlorine from outdoors into buildings at each location. A dose-response model translates chlorine exposures into predicted fatalities. Important parameters outside defender control include wind speed, atmospheric stability class, amount of chlorine released, and dose-response model parameters. Without fast and effective defense response, with 2.5 m/sec wind and stability class F, we estimate approximately 4,000 (half within ~10 minutes) to 30,000 fatalities (half within ~20 minutes), depending on dose-response model. Although we assume 7% of the population was outdoors, they represent 60-90% of fatalities. Changing weather conditions result in approximately 50-90% lower total fatalities. Measures such as sheltering in place, evacuation, and use of security barriers and cryogenic storage can reduce fatalities, sometimes by 50% or more, depending on response speed and other factors. © 2011 Society for Risk Analysis. Source

Fitzgerald G.A.,Abs Consulting
49th Annual Loss Prevention Symposium 2015, LPS 2015 - Topical Conference at the 2015 AIChE Spring Meeting and 11th Global Congress on Process Safety | Year: 2015

Consequence-based Facility Siting Studies (FSSs) typically requires the user assume a credible leak size to use in the evaluation of potential releases, which is often up to a 2" diameter leak. Many facilities tend to be less complex in comparison to large refineries or petrochemical plants, leading operators at the less complex facilities to ask why they should assume the same leak sizes as more complex facilities. Other facilities have unique processes with safety systems and factors they would like to quantify in a FSS. One solution would be to perform a Quantitative Risk Assessment (QRA) to capture the risks from all potential release locations and release sizes. However, many companies have not defined risk tolerance criteria and are resistant to do so for various reasons or do not want to invest in a QRA, which are more costly than a consequence-based study. A unique approach developed by ABS Consulting and first presented in 2011 is called the Maximum Design Leak (MDL) approach [1]. This approach calculates frequency-based leak sizes and then applies the leak size that exceeds a frequency criterion (events/year) in a consequence-based FSS instead of assuming a given leak size as credible. This avoids having to establish risk criteria in terms of fatalities/year and having to model a large number of scenarios yet takes advantage of many features in a QRA. This paper presents three case studies as examples of how the MDL has been applied and illustrates the advantages of calculating leak sizes specific to scenarios being evaluated for low complexity and low risk facilities. Source

Lee S.J.,Abs Consulting | Kim M.-H.,Texas A&M University
International Journal of Offshore and Polar Engineering | Year: 2011

The hydrodynamic interactions between an FT (Floating Terminal) and LNGC (Liquefied Natural Gas Carrier) in a side-by-side offloading arrangement as well as the dynamic coupling between the floating-body and inner-liquid motions are investigated by a potential-viscous hybrid method in time domain. For the time-domain simulation of the vessel motion, the hydrodynamic coefficients and wave forces are obtained by a potential-theory-based 3D diffraction/radiation panel program in the frequency domain. The ensuing simulations of vessel motions in time domain are carried out by using the convolution-integral method. The liquid motions in inner tanks are simulated in time domain by an FDM Navier-Stokes solver with a SURF scheme. The computed sloshing forces and moments are fed into the time integration of ship motion, and the updated ship motion is in turn inputted as the excitation force for liquid tanks; this is repeated for the ensuing time steps. For comparison, we independently developed a sloshing-motion coupled analysis program based on linear potential theory in the frequency domain. The developed computer programs are applied to the side-by-side offloading operation between the FT and LNGC. The frequency-domain results qualitatively reproduce the coupling effects, but the peaks are in general overpredicted compared to the experimental and time-domain results. The liquid-sloshing and vessel-motion interaction effects can further be intensified in the case of multiple floating bodies. © by The International Society of Offshore and Polar Engineers. Source

Goodno B.J.,Georgia Institute of Technology | Gould N.C.,Abs Consulting | Caldwell P.,Schneider Electric | Gould P.L.,Washington University in St. Louis
Earthquake Spectra | Year: 2011

The focus of this survey was to collect data on the performance of mechanical and electrical systems at selected critical facilities in Haiti. First-hand observations confirmed that nonstructural elements that are well anchored and=or laterally restrained will perform well during a moderate seismic event. However, the investigation also revealed that many critical institutions in Haiti did not utilize state-of-the-art engineering design or construction practices when installing nonstructural equipment that turned out to be crucial to their post-earthquake operations. The survey team believes that absent or poorly implemented seismic anchorage of nonstructural elements hampered the ability to restore essential systems to operation after the event. © 2011, Earthquake Engineering Research Institute. Source

Bardetsky A.,Abs Consulting
Collision and Grounding of Ships and Offshore Structures - Proceedings of the 6th International Conference on Collision and Grounding of Ships and Offshore Structures, ICCGS 2013 | Year: 2013

It is of primary importance in the aftermath of an accident to be able to assess the possibility of progressive structural failure of the damaged ship. The progressive structural failure caused by cracks emanating from the damaged area leads to a gradual reduction of the ship's residual strength, eventually leading up to the point of total hull girder collapse. This paper presents a procedure for predicting the crack propagation under sea wave loading using the fracture mechanics approach, the spectral fatigue approach and an equivalent stress intensity factor (SIF) range concept. The SIF is obtained from the finite element model of a damaged ship subjected to sea wave dynamic loading. The validity of the SIF obtained from the finite element modeling is confirmed by the independent weight function method widely used in fracture mechanics. The procedure for estimation of the crack propagation is proposed and implemented for a typical modern 170,000DWT bulk carrier in full load condition. The results of this research work can be used to support informed decision-making on the transit voyage from the accident location to the repair facility. © 2013 Taylor & Francis Group. Source

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