Notes on Sandia Study
These are my notes from the Study. It indicates that we should be more concerned about attacks than accidental release for double hulled transport ships. According to the authors, a wide range of experimental information on LNG spills and associated analyses must be considered and evaluated in an effort to assess the potential consequences of the breach and associated spill of an LNG cargo tank. The consequences or potential hazards to the public of a large LNG spill over water will depend on:
�� Potential damage to an LNG cargo tank from either an accidental or intentional breach and the size, location, release rate and volume of LNG spilled;
�� Environmental conditions such as wind, tides and currents, and waves that could influence the spread or orientation of a potential LNG spill over water;
�� Potential hazards resulting from an LNG spill over water, such as cryogenic damage or thermal damage to the vessel or other LNG cargo tanks, which might lead to cascading failures of additional LNG cargo tanks or several damage to the LNG vessel;
�� The location and magnitude of a potential LNG spill where the hazards from a spill, such as fire and thermal radiation, might impact or damage other critical infrastructures or facilities such as bridges, tunnels, petrochemical or power plants, government buildings or military facilities, national icons, or population or business centers; and
�� Potential impact on the regional natural gas supplies from the damage of an LNG vessel, unloading terminal, or loss of use of a waterway or harbor due to the immediate or latent affects of a spill.
Much remains unknown about what would happen if a transport ship is attacked because experiments and studies so far seem to be too small to yield reliable predictions.
However, based on the availble tests, the study suggests that, for most of the credible intentional breach and spill scenarios, the general distance for major structural damage (high hazards) can occur, on average, up to 500 m from a spill. In general, the distance to low thermal hazard levels, about 5 kW/m2, is approximately 1600 m for intentional spills. For a very large, cascading spill, the high hazard zones could approach 2000 m. Moreover, in the unlikely event the spill pool does not ignite before reaching its lower flammability limit, it could in approximately 8 minutes involve flames in an area with a radius extending 3614 m from the source depending on the environment.
By Al Pettigrew