Sandia National Laboratories Summary Guidance on Risk Analysis and Safety Implications of a Large Liquefied Natural Gas (LNG) Spill Over Water http://www.fossil.energy.gov/programs/oilgas/storage/lng/sandia_lng_1204.pdf Sandia National Laboratories February 2005 Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.

Key Features Impacting Possible LNG Carrier Spills If Ignition Occurs Artist’s Rendering Not to Scale Damage from LNG Spill Wind Tilts Fire Hole Size/ Spilled Volume Liquid Vaporization Liquid Spread Thermal Damage Due to Fire Fire Entrains Air Waves Affect Liquid Spread Picture of technical issues surrounding the modeling of an LNG spill and fire. This provides a visual perspective of what might happen in a spill and why the major concerns. Other possible hazards Fireball Late ignition and vapor cloud fire Analysis Requires Adequate Representation of Key Features Fire Increases Vaporization

Motivation and Scope of Sandia Study on LNG Spills Over Water An in-depth literature search of technical studies Detailed review of four recent spill modeling studies. Evaluation of the potential for, both accidentally and intentionally, breaching an LNG ship cargo tank. Assessment of the potential range of hazards involved in an LNG spill. Development of guidance on a risk-based approach to analyze and manage the threats, hazards, and consequences to reduce the overall risks of an LNG spill to levels that are protective of public safety and property. Studies are post 9/11/01. Originally the focus was to identify if any of the 4 studies reviewed provided a definitive analysis of the consequences of an LNG spill over water. All of the studies were examples of possible results but were not definitive in that they did not look at site specific conditions, guessed at hole sizes, etc. We were then asked by DOE to look at intentional threats and at developing guidance on the use of risk or performance-based approaches, which would include consideration of risk prevention and mitigation techniques, to protect public health and safety.

Extent of Thermal Hazards Predicted in Four Recent LNG Carrier Spill Studies This is the summary of the results of the four recent studies discussed. The focus of these analyses were on consequences not risk minimization. Utilization of risk prevention techniques were not considered. The various assumptions drive the prediction of potential hazard ranges. The studies looked at generally a small range of possible events. Cascading damage from cryogenic spills, thermal radiation from a fire, and impact on other infrastructures were not considered.

Suggested Risk-based Assessment Approach for LNG Carrier Spills Characterize Facilities Define Threats PA Risk = PA x (1-PE) x C C Determine Consequences Protection Goals Define Safeguards PE Analyze System Risk R This is the standard modern approach for risk management. It includes an evaluation of the threats, consequences, and safety effectiveness of an existing system. If after the evaluation the risks are acceptable, then you are done until a change in threat of consequences occurs. If the the risks are unacceptable, then changes can be made to reduce risks by improving protection, addressing the threat, accept higher consequences. Y Sufficient Protection ? N End Until Change Make Changes & Reassess

Safety and Consequence Analyses Considered accidental and intentional breaching events Collisions, groundings, impacts Sabotage and possible attacks Considered consequences from LNG carrier spills Fire and vapor dispersion hazards, explosions Reviewed over 100 reports on modeling and testing Considered possibility of cascading damage Cryogenic damage to LNG vessel and cargo tanks from a spill Thermal damage to structures and LNG cargo tanks from a fire Identified high, medium,and low consequence zones for range of possible spills

Estimated Impacts to Public Health and Safety from Accidental Spills Very low – little or no property damage or injuries Low – minor property damage and minor injuries Medium – potential for injuries and property damage High – major injuries and significant damage to property

Estimated Impacts to Public Health and Safety from Intentional Spills Very low – little or no property damage or injuries Low – minor property damage and minor injuries Medium – potential for injuries and property damage High – major injuries and significant damage to property

LNG Spill Safety and Risk Analysis Conclusions While there are limitations in existing data and modeling capabilities for LNG spills over water, current tools, if used as identified in the report guidance, can be used to identify and mitigate hazards and safely protect the public. As better models and additional data become available, they can be incorporated into the guidance. Consequences from accidental spills using current safety and security practices are generally low. Consequences from an intentional breach are much more severe than from accidents. Risk-based approaches should be used in cooperation with public safety and public officials to reduce the hazards and risks to public safety and property from potential LNG spills to levels compatible with site-specific protection goals.

LNG Spill Analysis and Risk Management Guidance Zone 1 (High hazard areas) Use modern Computational Fluid Dynamics models if interaction with critical infrastructures, terrain, etc. is possible Integral and similarity models can be adequately used if limited infrastructure interactions occur Risk prevention and mitigation and emergency response are very important and should be closely coordinated Zone 2 (Intermediate hazard areas) Similar to Zone 1 but less rigorous modeling and risk management operations required Zone 3 (Low hazard areas) Use of simpler models generally appropriate and nominal risk management operations