Federal energy department officials Thursday released documents showing that dozens of nuclear workers at Rockwell International in Canoga Park and its Santa Susana Field Laboratory were exposed to excessive radiation levels on occasions in the 1960s.
The records reveal no overexposures in subsequent years, and an energy department official described the 1960s events as "minor overexposures" with "no health consequences" for the workers.
But the records, provided to the Times by the Department of Energy under the Freedom of Information Act, do not include two overexposure events that Rockwell officials have said took place in the 1970s and 1980s. The records also do not mention the fact that Rockwell recently paid settlements in at least three workers compensation cases involving cancer deaths allegedly caused by radiation exposure. Rockwell paid the settlements in 1987-88 without admitting liability.
The documents released Thursday are called "unusual occurrence reports," which the DOE requires contractors such as Rockwell to file after safety or equipment problems.
Dick Nolan, special assistant to the manager of the DOE's San Francisco operations office, said the unusual occurrence files would not include alleged deaths from chronic exposure to low level radiation, such as the three workers compensation cases, because they "don't relate to any particular event."
Pat Coulter, a spokesman for Rockwell's Rocketdyne division, said the firm recognizes its "very serious responsibility" to operate safely.
For more than three decades, Rocketdyne and Rockwell's Atomics International divisions have worked for the energy and weapons programs of the DOE and its predecessor, the Atomic Energy Commission. While most nuclear projects have been carried out at the Santa Susana lab in Ventura County just west of Chatsworth, work has also been done at the company's plants on Canoga and De Soto avenues in Canoga Park.
Rockwell also works for DOE at the Idaho National Engineering Laboratory and until recently ran the plutonium production plants at the agency's problem-plagued Hanford Nuclear Reservation in Washington. In addition, Rockwell manages the DOE's Rocky Flats nuclear weapons plant near Denver, which is the subject of a criminal inquiry by the FBI and U.S. Environmental Protection Agency over alleged hazardous waste violations.
The documents released Thursday describe several episodes between 1960 and 1967 in which the radiation dose to workers at Santa Susana or the De Soto plant exceeded allowable limits of 3 rems per calendar quarter or 5 rems per year, as measured by film badges worn by the workers. Five rems is roughly equivalent to 100 to 200 chest X-rays, or up to 50 times the natural background radiation from the sun, rocks and soil.
Although 5 rems is not considered a high radiation dose, experts say a worker exposed to that level for 30 years has up to three extra chances in 100 of dying of cancer.
According to a report on a 1961 incident, an employee was assigned duties in a nuclear reactor room at the Santa Susana lab although his quarterly exposure was already near the 3 rem limit. His dose then rose to 3.455 rem, prompting AEC officials to ask Rockwell "why necessary precautions were not taken . . . to prevent the overexposure," according to correspondence in the report.
Rockwell responded in a letter that the work required such special skills that the exposure "could only be distributed among three qualified individuals," including the worker who was overexposed.
In another episode, workers at the De Soto plant were exposed to high levels of dust from enriched uranium while making nuclear fuel for several months in 1966 and 1967, the documents show.
The documents do not say how many workers were exposed, but in an interview Rocketdyne's manager of radiation and nuclear safety, Robert J. Tuttle, said 41 employees underwent medical testing because of the incident.
The fuel fabrication involved devices called "jaw crushers" used to reduce a uranium and aluminum mix to coarse powder. Workers were supposed to have been protected by shields, but dust leaked around the seals, according to a report.
In addition, Rockwell's safety effort was based on the wrong standard for airborne uranium, according to the report. The company was observing a standard six times weaker than the proper limit for the form of uranium involved, according to the documents.
In 1967, the company took corrective steps and performed medical tests that showed uranium particles in the lungs of a number of workers. Tests showed the workers were slowly excreting the uranium as it was transferred from their lungs to their bloodstream and gastrointestinal tract.
Tuttle said he believed 30 workers were found to have uranium in their lungs, but he said the levels were low, with only about three of the employees having the maximum amount of uranium in their lungs allowed by health standards.