The ARCO Chemical Co.'s inquiry into the plant explosion that killed 17 people has been stymied by a court order issued Saturday for the wife of a deceased worker. In response to her negligence lawsuit against the company, a judge granted a temporary restraining order preventing Atlantic Richfield Co. and ARCO Chemical from making any changes to the accident scene. Atlantic Richfield, based in Los Angeles, owns 83 percent of ARCO Chemical. ``We can't remove anything until OSHA releases the area to us,'' said Jack Johnson, president of ARCO Chemical Americas. He refused to comment further on the lawsuit, filed Friday by Sandra Lucas Davis. Her husband, Gregory Scott Davis, 27, was one of the names on a partial list of victims released by the company Saturday. State District Judge Shearn Smith issued the temporary restraining order, but it did not prohibit OSHA, the Occupational Safety and Health Administration, from conducting its investigation. OSHA officials, who were sifting through the damaged area, expect to complete their investigation in about a week, Johnson said. Assistant Secretary of Labor Gerard F. Scannell said Friday his agency was focusing on maintenance reports and complaints that employees had to work especially long hours at the plant. Plant manager Earl McCaleb said workers normally work 12-hour shifts for four days, then are off four days. Harold Sorgenti, president of ARCO Chemical, said the company was concentrating on helping families and employees deal with the deaths, while making sure the plant is stabilized. The explosion at about 11:30 p.m. Thursday ripped through the plant's utility area on the extreme southern end of the complex where employees were doing maintenance work, officials said. What the employees actually were doing ``will be determined by the investigation,'' Sorgenti said. ``Initially, they were beginning to fix a compressor.'' Initial speculation was that the five ARCO workers and 11 Austin Industrial Inc. contract workers killed were cleaning the 900,000-gallon tank that exploded. The other worker killed was the driver of a vacuum truck that was in the area to remove rainwater from a sump, McCaleb said. Sorgenti also said the investigation will focus on why so many people were in the area when normally five people are assigned there. ``I think it's difficult to understand why there was that concentration of employees in that area at that time,'' said Sorgenti, who flew to Houston from Europe where he was on business. McCaleb said it would be several months before the plant begins operating again. The 350 ARCO employees at the plant, about 15 miles east of Houston, are working to restore the plant and will not lose any pay, he said. The ARCO plant annually produces 560 million pounds of propylene oxide, used to make flexible foam for seat cushions and bedding. It also produces 1.3 billion pounds of styrene monomer, used for insulation, foam drinking cups, packaging materials and automotive parts; and 1.7 billion pounds of methyl tertiary butyl ether, a high-octane blending component used as a replacement for lead in gasoline. The explosion was the second major loss of life at a Houston area petrochemical facility in nine months. On Oct. 23, a series of explosions ripped through a Phillips Petroleum Co. plant in Pasadena, claiming 23 lives and injuring 130 people.