The lack of a metal brace led to an Oct. 15 accident in which sulfuric acid sprayed from a cracked pipe and burned a Hanford worker.

The acid's high temperature, chemical corrosion and the worker bumping the pipe may have contributed to the accident, Fluor Daniel Hanford officials said in releasing the results of on going investigation.

But the "root cause" was that an 8- to 12-inch stretch of polyvinyl chloride - or PVC - pipe holding sulfuric acid was not braced, said Bill Meader, leader of Fluor's investigation team.

The accident occurred at Hanford's Liquid Effluent Facility when 55 gallons of sulfuric acid spit out of a crack in the pipe and some of it burned Frances Wolfe, who was working nearby.

Wolfe, 54, had to have skin grafts on an arm and leg. She is expected to return to work in January.

The treatment facility takes low-level radioactive liquids and separates out contaminants. The sulfuric acid is used to raise the acidity of liquids that are not acidic enough to be treated.

The accident occurred at a pump that sends the acid from one section of pipe to another. That pump also has another PVC drain line that removes acid from the pump before maintenance work is done. When the pump is running, that short drain line is filled with acid.

Investigators found the drain line's PVC pipe was cracked along about 85 percent of its circumference at the threading where the drain line connects to the pump.

Investigators concluded the pipe was installed correctly but not braced, Meader said. They believe Wolfe, who was working next to the pump, dropped a rag, stooped to pick it up and bumped the pipe to cause the crack.

Wolfe did not see any acid dripping before the accident, and she remembered reaching for the rag. But she did not remember bumping the pipe, Meader said. An examination of the crack showed a bump, not corrosion, apparently created it, he said.

If the drain pipe had been adequately braced, a bump would not have caused the crack, said Meader and Kent Smith, Fluor's manager for 200 Area waste facilities. However, Meader said the pipe would have cracked eventually from the acid's high temperatures and corrosion.

Meanwhile, a team of managers and workers examined the plant to outline and begin tackling several extra safety measures.

At some locations, the PVC pipe was replaced with pipe of stronger and more acid-resistant stainless-steel alloy. And devices were installed to shut down pumps automatically when leaks occur.

In the Oct. 15 accident, workers quickly shut off the acid flow by hand, but more acid spewed out than would have with an automatic shut-off system.

Some protective clothing requirements also have been made stricter, and an employee now cannot work alone inside the facility. The facility's safety shower also was moved to a better location. The shower - where a splashed or contaminated worker can quickly wash chemicals off his or her skin and clothes - was about 10 yards from the accident site. But Wolfe had to walk a winding 30-yard pathway to reach the shower, Smith and Meader said.

Investigators also found the shower water splashed outside the stall and mixed with the spraying acid to create a potentially harmful sulfur dioxide gas. That danger was addressed by adding a curtain to the stall.

Meader and Smith saw one bright spot in the accident. Safety precautions adopted in the aftermath of the 1997 chemical tank explosion at the Plutonium Finishing Plant helped lessen the acid spill's effect. Emergency responses were badly bungled in the 1997 PFP accident, leading to a sitewide overhaul of safety measures.

That resulted in improvements and extra drills at the Liquid Effluent Facility. Consequently, Wolfe reacted calmly and quickly went to the shower, Meader and Smith said. Her co-workers quickly and properly helped her, turned off the acid flow and guarded the accident site. And Wolfe was on her way to a hospital within 20 minutes, the investigators said.