Some of the oil in the ship is still stored in multiple tanks, while more oil is trapped in voids and air pockets in various compartments, he said. The best estimates are that the oil, when it begins to escape in larger quantities over time, won't all rush out at once but will more likely escape in "smaller events," Russell said.

The oil on board the Arizona was thick Bunker C fuel oil that was used on many large military and civilian ships at the time, he said. The oil was so thick that it had to be heated and thinned so it could flow through pipes to the boilers that ran turbines and propellers to move the ship.

NIST's Foecke said the modeling software, when completed, could help evaluate hundreds of other shipwrecks off U.S. coasts and in inland waterways, where hazardous cargos or storage tanks full of fuel could be threats to the environment.

"This is the type of tool we want to develop so people can use it," he said.