The Nuclear Regulatory Commission has launched a last-minute inspection of a Texas nuclear power plant after reviewing hundreds of allegations from dozens of workers that the plant is poorly engineered, was constructed with substandard materials and may violate safety regulations.

But owners of the South Texas Nuclear Project near Bay City said the NRC has told them the inspection will not affect their application for a full-power license, which may be approved as early as next month.

The South Texas Nuclear Project is one of a handful of nuclear plants awaiting licensing by the NRC. The two-unit power station is owned by a four-utility consortium headed by the Houston Power & Light Co. (HP&L) and has been under construction for more than 12 years. The first unit of the $5.5 billion project was fueled last month and is expected to begin low-power operation this month.

Unlike the Seabrook and Shoreham nuclear plants still awaiting NRC licenses in the Northeast, the South Texas plant has not been a target of antinuclear activists or community opposition. However, it has been dogged by allegations of shoddy construction and inept management as its cost soared to more than 400 percent of the initial $1 billion estimate.

The NRC fined HP&L $100,000 in 1980, citing inadequacies in quality-control programs. A year later the utility fired its main contractor, Brown & Root, and hired the Bechtel engineering and construction firm to complete the plant.

NRC officials sent an inspection team to Bay City last week after reviewing more than 600 complaints of wrongdoing under Bechtel's management, about half involving potential safety defects. According to an NRC document, the alleged problems range from valves being installed backward to the use of welding materials, nuts and bolts that may not have been designed to handle the stress of a nuclear plant.

The allegations were made by more than 50 plant workers through the Government Accountability Project (GAP), an organization that defends whistle-blowers. GAP has refused to divulge names of the workers, who fear retaliation, but allowed the NRC to examine the complaints after a federal judge rebuffed NRC's effort to get the workers' names through a subpoena.

HP&L spokesman Graham Painter said the utility had not been allowed to see the allegations but said plant officials think that they are "old complaints."

"If that's the case, we're not concerned," Painter said. "If we looked at it, either we took corrective action or it didn't amount to much."

Edna Ottney, a nuclear consultant who investigated the complaints for GAP, said the allegations "touch just about everything," from improper installation of safety devices to falsification of thousands of quality-control documents on which the NRC relies to grant operating licenses.

"If 10 percent of these allegations are true, that plant is not safe," said Ottney, who has investigated similar complaints for the NRC. As an employee of a consulting firm under contract to the NRC, Ottney several years ago investigated worker complaints about the Tennessee Valley Authority nuclear plants, all of which are now closed for safety reasons.

South Texas, she said, "is worse than TVA. I would not live close to the South Texas plant."

John Corder, a former South Texas worker who agreed to be interviewed on the record, acknowledged that he reported problems to plant and NRC officials before taking them to GAP, but he contended that nothing was done to correct them.

Corder, a 27-year Bechtel employee who describes himself as a "good company man," was a superintendent at South Texas until he was dismissed last November as part of what the company said was a work force cutback.

"Nobody cares," he said. "Nobody wants to hear it. They're behind schedule and out of money. They say they'll fix it after the plant is running."

Corder accompanied the NRC inspection team on a tour Tuesday of the South Texas plant, where he had complained of numerous construction deficiencies in the recently completed Unit 1. Although he was not allowed to enter Unit 1 of the plant for what the NRC said were security reasons, Corder said he was able to point out identical problems with metal fasteners on an electrical panel in Unit 2.

"The fasteners are gone. Missing," he said. "The panel is just stuck up there." The panel is a protective covering over high-voltage switch plates that control electrical equipment in the plant.

Corder declined to characterize the plant as safe or unsafe. "It's muddled," he said. "I still worry about it at night."

NRC spokesman Joe Gilliland confirmed that Corder had earlier pointed out construction defects to an agency inspector. Gilliland said he did not know how serious the defects were or what corrections, if any, the agency had ordered.

According to NRC and GAP documents, other workers have raised questions about the adequacy of electrical splices, pipe joints and welds. While the individual complaints may appear minor, Ottney said, they suggest that the plant's quality-control program is defective.

The NRC inspects relatively little of a nuclear power plant before deciding whether to grant it an operating license. Instead, the agency relies heavily on a "paper trail" of quality-assurance documents that are supposed to ensure the plant meets NRC standards as it is being built.

Ottney said several quality-control inspectors told her that they were instructed not to verify construction documents and that most said they complied for fear of losing their jobs. "The reason they are rolling over now is that TVA and South Texas are about your last nuclear jobs," she said. "There are no other jobs for them. It was the last hurrah."

"I expect that's a factor," said Corder, who worked on more than a half-dozen nuclear plants for Bechtel dating back to the early 1960s. "I have pointed out engineering flaws before, and it was always an arm-wrestle. But it never before led to a vendetta against employees like it has here."

Painter said NRC officials had told the utility that "it's typical to have these allegations at the last minute" and that the review "should have no effect on licensing."

NRC spokesman Gilliland said the agency may have told HP&L that the latest inspection "has not been a delaying factor" in the licensing process because a commission vote on the license has been postponed for other reasons.

Low-power tests were delayed last month when the plant developed an unexplained vibration in its cooling system, and the NRC is analyzing a potential problem with its "thimble tubes," shafts that are used to introduce sampling equipment into the reactor. The tubes corroded in a similar plant in Belgium, allowing radioactive water to spill into the reactor building.