NS&D Monitor
7/3/2014
Y-12 Oxide Conversion Facility Runs for First Time in More Than a Year
For the first time in more than a year, the problem-plagued Oxide Conversion Facility has been successfully operated at the Y-12 nuclear weapons plant in Oak Ridge. Y-12 spokeswoman Ellen Boatner said the restart occurred last week, but she did not have information on the extent of the run or future plans for the OCF, which is housed in the plant’s 9212 uranium processing complex. Oxide Conversion is considered a critical part of Y-12’s ability to recycle scraps of weapons-grade uranium and return the material for reuse in nuclear weapons or other projects.
Efforts to resume operations have been interrupted time after time in recent years because of equipment problems, technical issues or safety concerns. Steven Wyatt, a spokesman for the National Nuclear Security Administration, confirmed that the last time the OCF operated was in March 2013, but he said operations reportedly occurred for just a short time. And, the previous operation before that was a year earlier, according to various reports.
Resumption of Operations Finds Mixed Success
The Oxide Conversion Facility converts enriched uranium from an oxide form to uranium tetrafluoride—known as “green salt”—which then goes through a reduction process to form a purified uranium metal. In recent months, a leaking cylinder of hydrogen fluoride has stalled attempt to return operations at OCF. According to a June 6 report by staff of the Defense Nuclear Facility Safety Board, attempts to resume activities with the “hydrofluorination bed operations at OCF” were met with mix success. “This was Enriched Uranium Production’s second attempt to operate the bed since hydrogen fluoride leaks in the vaporizer enclosure halted operations last August,” the report stated. “EUP operators suspended operations prior to the introduction of HF due to indications of an obstruction impeding the flow of nitrogen to the bed. Engineering personnel are working with EUP personnel to develop a procedure that would allow operators to oscillate the flow of nitrogen in an attempt to dislodge the obstruction.”
There have been a number of reported complications in changing out the HF cylinder that feeds the system. The leaking cylinder was reportedly sent back to the vendor, but the NNSA has refused to confirm the vendor’s name, the cost or other details.
Exposures in 1958 Y-12 Criticality Worse Than Previously Believed
Newly released information indicates that more than 30 workers at the Y-12 nuclear weapons plant received significant radiation exposures in the plant’s worst-ever accident, a nuclear criticality that occurred in 1958. The National Institute for Occupational Safety and Health conducted a dose-reconstruction of the accident in 2006 to prepare for applications from Y-12 workers seeking compensation from the Energy Employees Occupational Illness and Compensation Program.
Previous reports have always indicated there were eight victims who received severe radiation doses from the accident in a wing of Y-12’s 9212 complex, but the NIOSH report—released by Oak Ridge Associated Universities, a NIOSH subcontractor—shows the exposures reached others in the building besides the eight nearest the source.
31 Individuals Exposed to Radiation During Incident
The NIOSH report estimated the doses received by 31 individuals when a solution of weapons-grade uranium was inadvertently drained into a 55-gallon drum in the C-1 wing of 9212. The container was unsafe for the enriched uranium, which generated an uncontrolled nuclear chain reaction that released dangerous levels of radiation. NIOSH provides dose reconstruction and other scientific support for the compensation program, which was established by Congress in 2000. The NIOSH report was published as a “technical information bulletin” in May 2006.
Those eight workers who were previously acknowledged as the most exposed individuals are included in the NIOSH accident analysis, and their doses are generally the highest of the group—some of them estimated at more than 1,000 rems. However, some of the other workers exposed during the Y-12 accident also received significant doses of radiation. The workers are identified in the report by a number and job title. Particularly notable was an equipment tabulation clerk who was 29 feet from the radiation source and received a total dose estimated at 221 rems. Others in the federal report include four chemical operators who received doses estimated at between 18 and 40 rems.
Employees Hundreds of Feet Away Exposed
Some employees were hundreds of feet away from the accident scene but still received radiation doses, apparently because of the penetrating neutrons from the fissioning source. Those included a record clerk, engineer, a couple of lab analysts, a development engineer, product inspector, chemist, road foreman, stenographer, development engineer, and receiving clerk.
Stuart Hinnefeld, director of NIOSH’s Division of Compensation Analysis and Support, said the study was prompted after one of the individuals involved in the 1958 accident filed a claim for compensation. When NIOSH asked the U.S. Department of Energy for the worker’s history of radiation exposures, the response from DOE did not include any dose information from the 1958 criticality accident—even though the individual had cited it on the application, Hinnefeld said. “So we made supplemental inquiries to DOE about it and then received quite a lot of information,” he said.
Unclear How Many Employees Have Pursued Claims
Hinnefeld said he could not say how many of the Y-12 workers—or their surviving family members—have filed claims for compensation based on their exposures in the criticality accident that occurred 56 years ago. He also said he couldn’t comment on how many have collected from the government fund. Hinnefeld said NIOSH doesn’t consider any of the doses to be insignificant, even the lowest ones, but he said the decision on whether the radiation was sufficient to cause cancer is sometimes a complex evaluation.
In order to collect from the compensation program, it must be determined that it was at least as likely as not that a worker’s career radiation dose was enough to have caused the cancer. Some early workers at Y-12 have been able to collect from the compensation program without having to go through the formal “dose reconstruction” process. That’s because of their status as a “Special Exposure Cohort.” Initially, people who worked at Y-12 between 1943 and 1947 were granted that status because of the paucity of radiation records or uncertainty about their accuracy. If they developed one of 22 types of cancer that qualify under the program’s guidelines, the workers were immediately eligible to collect $150,000 and receive medical care. In late-2011, the Special Exposure Cohort at Y-12 was expanded to include people who worked at Y-12 for at least one year between 1943 and 1957.
