RANDALL CHASE Associated Press Writer - May 19, 2009

CLAYMONT, Delaware (AP) — A blaze caused by a home-rattling explosion at a Delaware oil refinery has been extinguished, and investigators were looking into the cause, officials said Monday night.

Carol Sloan, a spokeswoman for Sunoco Inc., said officials hope to start the on-scene investigation Tuesday, but won't be able to assess the damage from Sunday night's blast until it is safe to go into the area. Alan Brown, chief deputy fire marshal for the state, said it will probably be a couple of days before any preliminary findings are made.

No injuries were reported and no evacuations of surrounding neighborhoods were ordered.

The 781-acre (316-hectare) complex ranks 39th by total production out of the 150 operating refineries in the U.S., according to the U.S. Department of Energy. While the blast hit an area that makes a chemical used in plastics, Sunoco Inc. spokesman Thomas Golembeski said gasoline production at the refinery will also be affected.

"There has been some production impact to other units in the refinery ... I can't quantify it at this point," he said.

Experts say the gasoline supply nationwide is plentiful because Americans are driving much less in the recession.

Some production employees were at work at the open refinery, and Golembeski said the company was monitoring air quality every hour and the readings indicated that "the situation is safe."

New Castle County, Delaware, county councilman John Cartier said he felt the blast and could see the flames from his home at least three miles (five kilometers) from the refinery.

"It was almost like seismic," he told The (Wilmington) News Journal. "My house was rocked. It was a big large boom."

At one point, up to 50 firefighters from Delaware and Pennsylvania were at the scene.

Golembeski said the explosion and fire was contained to the ethylene unit and did not affect an adjacent chemical plant that makes polypropylene, a tough plastic used for food containers and molded auto parts, among many other items. The ethylene unit has been shut down. Ethylene is a feed stock used in the production of plastics.

But some refining in other units was affected, and he said the company was working with two of its upriver refineries — at Philadelphia and Westville, New Jersey — to "optimize production" and meet customer demands.

He could not specify how much production was affected at the refinery, which can process about 175,000 barrels of sweet crude oil per day into various petroleum products, including gasoline, jet fuel and home heating oil. The Philadelphia refinery can process about 330,000 barrels per day, and the New Jersey refinery has a capacity of 150,000 barrels per day.

It adjoins an international seaport and operates around the clock seven days a week with about 700 employees, refining oil primarily from fields in the North Sea and West Africa.