Honeywell Specialty Chemicals, Metropolis
Metropolis -- the home of Superman -- really exists in Southern Illinois. The real town of Metropolis, Illinois itself was founded in 1839 on the Ohio River at the southern tip of the state - and is said to be the only Metropolis listed in the United States Postal Directory [actually there is another Metropolis in Louisiana].
Located 3 km northeast of Metropolis, Illinois there is a uranium conversion facility. The plant, Honeywell Specialty Chemicals in Metropolis, Illinois, has a nominal capacity of 12,700 metric tons of uranium per year. The plant manufactures a variety of products, but about 80 percent of the plant's work involves refining raw uranium ore into UF-6. Across the river in Paducah, Kentucky lies a gaseous diffusion plant.
After uranium is processed into yellow-cake at a mill, it is sent to a facility to be converted into uranium hexafluoride (UF6). The only conversion facility in the United States is located in Metropolis, Illinois. The UF 6 is solid under normal temperatures and pressure, but becomes a liquid at higher temperatures. It may produce a gas from a solid or liquid state. The material is then sent to one of the country ’s two gaseous diffusion plants to enrich its uranium concentration.
The most significant hazard at a uranium conversion facility exists at the stage where liquid UF 6 is stored and processed. When liquid UF 6 is released to the atmosphere,it reacts with the moisture in the air to form a dense vapor cloud that contains hydrogen fluoride (HF)gas, a non-radioactive, extremely toxic substance. In 1986, at the Sequoyah Fuels Corporation conversion facility in Gore, Oklahoma, an overfilled cylinder of UF6 ruptured, resulting in a major release of hydrogen fluoride that killed a worker. This facility was later closed by its owner.
ConverDyn, a general partnership between affiliates of Honeywell and General Atomics, is the exclusive agent for conversion sales from the Metropolis Works.
The dry fluoride volatility conversion process developed by Honeywell Inc. is comprised of 5 main stages: Sizing, Reduction, Hydrofluorination, Fluorination and Distillation, along with auxiliary processes such as waste treatment and sodium removal. Once fed into the conversion process, the yellowcake is uniformly sized and reacted with hydrogen at a high temperature to form uranium dioxide (the Reduction stage). Next, the uranium dioxide (UO2) is reacted with anhydrous hydrofluoric acid in fluidized bed reactors during Hydrofluorination to yield uranium tetrafluoride (UF4). The UF4 is reacted with gaseous fluorine to produce crude gaseous uranium hexafluoride (UF6) in the Fluorination stage then enters the final Distillation stage. Here light fraction gases and impurities are removed to produce a purified liquid UF6. This liquid UF6 is drained into 14-ton cylinders where, after cooling for 5 days, the UF6 crystallizes.
The Nuclear Regulatory Commission staff informed officials of the Honeywell International, Inc. uranium hexafluoride processing plant in Metropolis, Illinois, on 14 April 2004 that the agency has no objection to the restart of the second stage of a three-stage process leading to resumption of production at the facility.
On 27 March 2004, the NRC staff authorized the company to resume ore preparation, the first stage in a process that has been shut down since a 22 December 2003 release of uranium hexafluoride to the environment outside the plant. The April 14 authorization allows resumption of the production of uranium tetrafluoride (UF4), called green salt. NRC inspectors continue to review company preparations to resume the fluorination process which culminates in production of the final product, uranium hexafluoride (UF6).
The NRC sent the company a Confirmatory Action Letter following the 22 December 2003 release which stated that Honeywell would discuss with the NRC both the results of its own investigation and proposed corrective actions prior to restarting the processes involved in the incident.
Based on NRC inspectors’ reviews of corrective actions and observation of work activities, the agency is satisfied that the company’s actions have been adequate to allow the safe restart of ore preparation and uranium tetrafluoride. NRC inspectors will continue to observe ore preparation and production of uranium tetrafluoride, along with the company’s activities related to preparation for resumption of the final stage of the process.
