Oxide Conversion (X-705E)

Over its entire period of operation (1957 to 1978), the oxide conversion process was probably one of the most hazardous radiological and chemical operations at PORTS. The X-705E oxide conversion facility was originally designed to recover oxides of uranium, primarily from decontamination solutions in X-705 and incinerator ash, into UF₆ for feed into the cascade. Between 1959 and 1961, uranium oxides from spent reactor fuel were also processed in the facility. The process was contained in two areas, “E” and “H,” located in the northeast corner of the X-705 building. The E area, on the ground floor, contained the oxide weighing, storage, unloading, and sampling rooms; the flame tower room; and the cold trap room. The H area was located directly above the E area and contained the flame tower cleanout port, the upper section of the feed hopper, the magnesium fluoride traps, vacuum pumps, and various filters. The H area was also used to store uranium oxide canisters, contaminated waste, idle equipment, and wash solutions.

The general material flow consisted of initial receipt and weighing of oxide, sampling, grinding in preparation for feeding, and then feeding the oxide into a fluorination reactor (initially a stirred bed, then a flame tower). The resulting UF₆ was filtered through sintered metal filters and magnesium fluoride traps to remove heavy metal contaminants, and then captured in a “cold trap.” When full, the cold traps were heated, and the liquefied UF₆ was drained into cylinders, depending on the assay. Initially, the process consisted of a stirred bed reactor, using a belt that moved the oxide through a pipe in a fluorine atmosphere. Later, a shaken bed reactor was used because of unreliable belt operations. Both methods had very low production capabilities. A demonstration facility with a 3-inch flame tower was built and operated from 1958 through 1965, but was shut down due to health physics concerns and uranium material balance problems. Problems identified by an Oak Ridge health protection review in 1965 included potential concentration of transuranics in the processes, internal uranium exposures from enriched insoluble oxides that were not detectable by urinalysis, and inadequate air monitoring capability. Although the need to study the transuranic contamination potential and the addition of a separate tower for re-feed of tower ash were identified by the Oak Ridge review, neither activity was implemented. The presence of transuranic contamination in feed material was not adequately considered in the design or operation of the oxide conversion process.

Although the tower room typically contained the highest radiation and contamination levels, most operations and maintenance exposures did not occur in the tower room. Primary activities resulting in exposures in excess of PALs included handling of oxide powders in preparation for feeding to the towers, changing the tower feed screw, connecting and disconnecting pigtails, and performing maintenance on cold traps plugged with foreign materials.

A handwritten report entitled “Oxide Conversion as Viewed by Development” was written by a member of the Development Department (circa 1966) in response to a significant error in the uranium mass balance in X-705E. The report explained that the oxide conversion process was originally established as a waste recovery process and not a production process. The subsequent introduction of reactor returns converted X-705E into a production facility, requiring a capacity that “it was ill equipped to handle.” The report further explains that uranium inventory control and health physics concerns were secondary to production schedules and costs, until “eventually the

inevitable happened.” The author’s reference to “the inevitable” was directed primarily at the uranium inventory problem, but also refers to health physics problems. This report provides evidence that the operating contractor was aware of safety problems in X-705E; however, production schedules were viewed as more important. The report also refers to the practice of “de-smoking ash pots through the building ventilation system” as a possibility for physical losses of small quantities of uranium. Since the building ventilation system was unfiltered and reactor return materials had been processed, transuranics from the ash pots likely entered the building ventilation system and were subsequently released to the environment but not monitored.

A 1968 paper entitled “Fluorination of All Enrichments of Uranium Oxides” by the Production Division - Chemical Operations Department, presented at the Rocky Flats fluoride volatility meeting on June 24, 1968, also describes 1964 health physics concerns that led to the decision to enclose the process in a glovebox. The paper cites several concerns, such as the average assay of reactor scrap being higher than that previously handled, the quantity of material processed contributing to problems, and mandatory respiratory protection while processing oxides. In July 1967, process modifications were completed, and operations resumed in mid-November 1967.

Efforts to reduce health physics and contamination problems between 1967 and 1973 were ineffective, primarily because of poor practices by operators and supervisors. Training lecture notes from the late 1960s or very early 1970s, labeled “Health Physics in the Oxide Conversion Area,” described problems with health physics practices after completion of those

modifications. The notes indicated that it was common practice for operators to remove gloves from the gloveboxes to conduct some operations. It further discussed problems with deterioration of the gloves from the fluorine atmosphere inside the glovebox and indicated that oxide conversion was never intended to be a clean process. On January 30, 1970, an Industrial Hygiene and Health Physics internal memorandum discussed employee disregard for protective measures, lack of required protective measures in X-705E, problems in contamination control, and releases in the cold trap area from faulty cylinder valves and ruptured pigtails. It also noted that most of the exposures could be prevented with proper respiratory protection. Further, Industrial Hygiene and Health Physics found that many of the exposures could have been reduced and/or avoided by stricter adherence to operating procedures. A March 1973 OR appraisal cited ongoing poor health physics practices in X-705E, including a large number of radiological occurrences, ignored alarms, eating and drinking in the cold trap room, work performed without respiratory protection, and increasing lung burdens for some operators.

A 1976 memorandum (Memo GAT-922-76-184) identified transuranics as a problem at PORTS, especially in the oxide conversion process. PORTS had an existing inventory of transuranic-contaminated feed materials for oxide conversion and wanted to process that material. Based on recommendations from OR, Goodyear Atomic Corporation performed a variety of process improvements and test runs to model fluorination of transuranics and reduce system leaks and contamination. On September 13, 1978, Health Physics management determined that those efforts were not sufficient and recommended shutting down X-705E due to unacceptable health risks. On October 1, 1978, the oxide conversion facility was placed in a standby status; on December 14, 1978, Goodyear Atomic Corporation requested cancellation of the oxide conversion project.

It appears that during its entire operation, the oxide conversion process placed Plant personnel working in the area, as well as security guards who may have been on patrol, at risk of exposure to chemicals and airborne radioactivity. Processing of transuranic-contaminated material was not adequately anticipated in the original or subsequent designs or operation. Samples obtained after shutdown showing the presence and level of transuranic contamination in the facility indicate that worker airborne exposures could have exceeded the acceptable standards, especially given the apparent lack of discipline in respirator use.

3.2.3 Cascade Operations