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PUBLIC HEALTH ASSESSMENT

US DOE PORTSMOUTH GASEOUS DIFFUSION PLANT
PIKETON, PIKE COUNTY, OHIO


SUMMARY

The Portsmouth Gaseous Diffusion Plant (PORTS) is near the Village of Piketon in rural South-central Ohio. The portions of the plant responsible for the enrichment of uranium for use as nuclear fuel in commercial power plants are operated by the United States Enrichment Corporation (USEC) for the United States Department of Energy (US DOE). The plant enriches uranium in the chemical form of uranium hexafluoride, which ultimately decomposes to uranium oxide and hydrogen fluoride in moist air. Uranium concentrations on-site and off are similar to those found throughout South-Central Ohio, and therefore do not indicate any history of uranium releases. Site-related contamination and hydrogen fluoride releases pose no apparent public health hazard to off-site communities.

In 1992, Pike and Scioto County residents petitioned the Centers for Disease Control and Prevention (CDC) to conduct an epidemiological health study. Residents expressed their desire for a health study on radiation related diseases. The petition was forwarded to the Agency for Toxic Substances and Disease Registry (ATSDR) to perform a public health assessment to determine what follow-up health activities, such as a health study, are appropriate. ATSDR, through its public health assessment process has not found exposure data to support a health study.

There appears to be no off-site threat to public health from any site activity or release. ATSDR found off-site contamination was not at levels that could cause adverse health effects. Radiation measurements off-site did not exceed normal variations in background for the region.

Residents have raised questions about excessive cancer rates in Scioto County, excessive birth defects, and other adverse health effects believed to be related to environmental releases from the site. Available information about health outcomes does not suggest any adverse health impact from site operation. Detailed answers to those questions appear in the Public Health Implications and Community Concern sections of the public health assessment.


BACKGROUND

The Agency for Toxic Substances and Disease Registry (ATSDR) was petitioned by several groups to perform a health study of the people living near the Portsmouth Gaseous Diffusion Plant, near Piketon, Ohio.

A. Site Description and History

The Portsmouth Gaseous Diffusion Plant (PORTS) is operated by the U.S. Department of Energy (DOE), and uranium enrichment facilities involved in the production of Low Enriched Uranium (LEU) are leased to the United States Enrichment Corporation (USEC). On site are the Gaseous Diffusion Plant (GDP), built between 1952 and 1956, and the Gas Centrifuge Enrichment Plant (GCEP), whose construction was halted in 1985. Before November 1986, the site was operated by the Goodyear Tire and Rubber Company (Goodyear Atomic Corp.). PORTS is one of the two operating uranium enrichment facilities owned by DOE. The other is in Paducah, Kentucky.

Location of PORTS The location of the plant site is shown on the map of Ohio in Figure 1. The facility is located in sparsely populated, rural Pike County, Ohio, on a 6.3-square-mile site about 2 miles east of the Scioto River at an elevation approximately 120 feet above the Scioto River floodplain. The terrain surrounding the plant, except the floodplain, consists of marginal farmland and densely forested hills. The floodplain is farmed extensively, particularly with grain crops.

The principal site process is the separation of uranium isotopes through gaseous diffusion, specifically to produce enriched uranium with a higher concentration of 235U. PORTS has been producing enriched uranium by the gaseous diffusion process since 1955. This enriched uranium has been produced to meet the needs of both government and private industry.

The gaseous diffusion process for uranium enrichment, utilizes uranium in the form of uranium hexafluoride (UF6) and is based on the fact that lighter molecules diffuse slightly faster than heavier molecules through the walls of a porous tube called a barrier. The enrichment is performed in three process buildings: X-333, X-330, and X-326. The buildings house more than 4,000 stages of compressors and converters and cover more than 8 million square feet of floor space. The site layout is depicted in Figure 2.

 

 

PORTS Site Map

The portion of gas passing through the barrier wall is slightly richer in 235U [1] . Support operations include feeding and withdrawal of material from the primary process, treatment of water for both potability and cooling, steam generation for heating, decontamination of equipment removed from the plant for maintenance or replacement, recovery of uranium from various waste materials, and treatment of industrial wastes.

The plant currently employs approximately 2,600 people, excluding temporary construction workers. In addition to the process buildings, PORTS includes facilities for administrative activities, utilities operations, chemical operations, maintenance, laboratory functions, storage and other miscellaneous activities.

Surface Water Drainage to Off-Site Local tributaries flowing into the Scioto River are relatively unpolluted [17],[18] except for contamination introduced by runoff from farms. PORTS plant effluents discharge into Little Beaver Creek, Big Run Creek, two pipelines, and the west drainage ditch, all of which ultimately flow into the Scioto River, shown in Figure 3.

B. Site Visit

ATSDR personnel visited the Portsmouth Gaseous Diffusion Plant June 15-17, 1993, and made the following observations:

  • The site is nestled in a low spot in the local terrain and ringed by dense forest to the north, east and west, and by low hills to the south.

  • The industrialized portion of the site is guarded 24 hours per day, is monitored by a video system, and is fenced with razor wire to prevent unauthorized access.

  • There are a number of farms at the site boundary.

  • A large amount of healthy vegetation was seen within the site boundary, outside of the industrial area. No indication of ecological stress was observed either on or off site.

  • Many residences near Piketon appeared smaller than 800 square feet, and some had only partial indoor plumbing. Several residences had coal cook-stoves burning, even though the outside temperatures were about 90F.

C. Classified Document Review

Cleared personnel from the Agency for Toxic Substances and Disease Registry reviewed classified documents at the PORTS site on July 6 and 7th, 1995. ATSDR reviewed classified incident reports and release information, and found no incidents not reported in environmental monitoring reports. This review clarified that there were no unreported releases of hazardous substances to the environment from the site. Furthermore, the process that releases hydrogen fluoride was shown to be continuous and not batch as previously thought.

D. Demographics, Land Use, and Natural Resources

Regional Demography

The Portsmouth site is in Pike County in southern Ohio. Pike County and the six surrounding counties are largely rural and relatively sparsely populated. Approximately 275,000 persons lived in the 7 counties in 1990. Counties directly adjacent to Pike are Adams, Highland, Jackson, Ross and Scioto. Vinton County, to the northeast, is the closest non-adjacent county surrounding Pike County.

Census Tracts Around PORTS

Demographic and socioeconomic data from the 1990 census for Pike and six surrounding counties are in Tables 1 and 3. All the listed counties appear to have similar demographics. Well over two-thirds of the population of each county live in owner-occupied housing units, which suggests a stable, non-transient population.

Data from the 1990 census are presented in Tables 2 and 4 for census tracts 9522, 9523, and 9527 in Pike County and 9921, 9922, and 9923 in Scioto County. The site is located in tract 9522, and the other tracts border 9522. The relationship of these census tracts to the PORTS site is shown in Figure 4.

Many of the percentages for the variables for tract 9922 differ substantially from those for the other tracts because there is a prison in tract 9922.

Table 1. Socioeconomic Data by County

  Adams Highland Jackson Pike Ross Scioto Vinton
Median Household Income, $ 16,318 21,505 18,298 19,486 24,286 17,595 19,066
Per Capita Income, $ 8,407 9,848 9,228 8,958 10,758 9,253 8,826
% Persons Below the Poverty Level 28.5 16.5 24.2 26.6 17.7 25.8 23.6
% Persons Age 25+ with High School Equivalency or Higher 58.4 66.5 60.9 60.8 67.6 63.8 58.7
% Occupied Housing Units Lacking Complete Plumbing 8.3 3.8 4.6 5.3 2.8 2.5 8.9
% Occupied Housing Units on Public Water Source 73.5 74.1 77.1 72.4 72.7 93.0 37.3
% Occupied Housing Units Using Private Wells or other Water Source 26.5 25.9 22.9 27.6 27.3 7.0 62.7
Source: Census of Population and Housing, 1990: Summary Tape File 3 on CD-ROM [machine readable files] (Ohio) / prepared by the Bureau of the Census, Washington: The Bureau [producer and distributor], 1992.


Table 2. Socioeconomic Data by Census Tract

  9522 9523 9527 9921 9922 9923
Median Household Income, $ 17,785 17,786 16,540 20,343 19,156 16,481
Per Capita Income, $ 8,336 8,749 7,715 9,104 6,646 7,112
% Persons Below the Poverty Level 30.3 32.7 33.9 26.2 24.0 28.9
% Persons Age 25+ with High School Equivalency or Higher 55.5 61.4 56.8 67.1 58.9 51.6
% Occupied Housing Units Lacking Complete Plumbing 5.6 1.0 12.1 4.2 3.5 9.0
% Occupied Housing Units on Public Water Source 67.0 85.0 38.9 89.6 92.7 73.2
% Occupied Housing Units Using Private Wells or other Water Source 33.0 15.0 61.1 10.4 7.3 26.8
Source: Census of Population and Housing, 1990: Summary Tape File 3 on CD-ROM [machine readable files] (Ohio) / prepared by the Bureau of the Census, Washington: The Bureau [producer and distributor], 1992.


Table 3. Population Data by County

  Adams Highland Jackson Pike Ross Scioto Vinton
Total Persons 25,371 35,728 30,230 24,249 69,330 11,098 8,826
Total Area (square miles) 584 553 420 442 688 612 414
Persons per Square Mile 43 65 72 55 101 131 27
% Male 49.1 48.6 47.7 48.7 52.1 48.5 49.1
% Female 50.9 51.4 52.3 51.3 47.9 51.5 50.9
% White 99.4 97.6 98.9 98.2 92.8 96.2 99.8
% Black 0.2 1.9 0.7 1.3 6.4 3.1 0.0
% American Indian, Eskimo, or Aleut 0.3 0.2 0.2 0.3 0.2 0.5 0.1
% Asian or Pacific Islander 0.1 0.2 0.1 0.2 0.4 0.2 0.0
% Other Races 0.1 0.1 0.1 0.0 0.1 0.1 0.0
% Under Age 10 15.1 14.9 14.4 15.3 13.4 14.2 14.3
% Age 65 and older 13.5 15.0 14.0 13.6 12.4 14.9 13.7
Source: Census of Population and Housing, 1990: Summary Tape File 1A (Ohio) [machine readable files] (Ohio) / prepared by the Bureau of the Census, Washington: The Bureau [producer and distributor], 1991.

Nationally, the percentage of persons more than 65 years old was 12.5 percent, according to the 1990 census. For the same year, the fraction of persons in Ohio more than 65 years old was 13.6 percent. Table 3 shows that Scioto County in Ohio was more than a percentage point higher than the national or state for this age group. Since the elderly are more prone to sickness, this could result in Scioto County's having higher rates of disease than the state of Ohio or the nation.

Table 4. Population Data by Census Tract

  9522 9523 9527 9921 9922 9923
Total Persons 5,023 4,479 3,462 4,584 5,614 4,425
Total Area (square miles) 119.7 58.9 110.6 50.7 39.7 120.5
Persons per Square Mile 42 76 31 90 141 36
% Male 50.1 47.3 50.5 49.1 68.0 49.3
% Female 49.9 52.7 49.5 50.9 32.0 50.7
% White 95.7 98.1 99.6 99.5 77.7 97.7
% Black 4.0 1.3 0.0 0.1 21.6 0.2
% American Indian, Eskimo, or Aleut 0.2 0.3 0.3 0.2 0.3 1.9
% Asian or Pacific Islander 0.1 0.3 0.1 0.1 0.0 0.1
% Other Races 0.0 0.0 0.0 0.2 0.4 0.1
% Under Age 10 16.3 16.4 16.1 15.5 8.9 15.3
% Age 65 and older 10.5 13.8 10.5 12.3 7.0 13.2
Source: Census of Population and Housing, 1990: Summary Tape File 1A (Ohio) [machine readable files] (Ohio) / prepared by the Bureau of the Census, Washington: The Bureau [producer and distributor], 1991.

Figures for a number of the variables listed in tables 1 through 4 indicate that the site is located in a relatively impoverished area. The percentage of persons living below the poverty level is considerably higher than would be expected. The percentage of high school graduates, median household income, and per capita income are relatively low. Low socioeconomic status is often consistent with poor access to health care.

Pike County had approximately 24,249 residents as of the 1990 census. Scattered rural development is typical; however, the county contains numerous small villages such as Piketon, Wakefield, and Jasper, which lie within a few miles of the plant. The county's largest community, Waverly, is about 12 miles north of the plant site and has a population of approximately 5,100 residents. The closest residential center is Piketon, which is about 5 miles north of the plant on U.S. Route 23; its 1986 population was 1,900. Several residences are adjacent to the southern half of the eastern boundary and along the Wakefield Mound Road (Old U.S. 23) directly west of the plant. Two nursing homes with a combined capacity of 60 persons are located along Wakefield Mound Road.

Additional population centers within 50 miles of the plant include Portsmouth (population 25,500), 27 miles south; Chillicothe (population 23,420), 27 miles north; and Jackson (population 6,675), 18 miles east. The total population of the area within a 50-mile radius of the plant is approximately 600,000. The prison in census tract 9922 holds roughly 1,200 inmates. Population density around PORTS is shown in figure 5.

Population Density Around PORTS

Census tract 9522 contains the site and also the residences of those people living immediately around the site boundary. As many as a third of those living adjacent to the site rely on private wells as their primary source of drinking water. The remaining two-thirds are on the public water system. Public water for the area comes from the Scioto River and aquifers associated with the river.

Land Use and Natural Resources

Land use is important in determining the impact of plant operations. Pike County consists primarily of farmland (including cropland, woodlot, and pasture) and forest (including Pike State Forest and portions of Wayne National Forest), with urban and suburban areas occupying about 1% of the total land area.

The croplands lie mostly on or adjacent to the Scioto River floodplain and are farmed intensively, particularly with grain crops, such as corn and soybeans. Other produce, such as tobacco, tomatoes, cabbage, and fruits, are also cultivated in the area. Hillsides and terraces are more commonly used for cattle pasture than for crops. Until recently, both dairy and beef cattle were raised in the area of the Portsmouth site, but only beef cattle are currently pastured within 10 miles of the site. Other farm animals, such as horses, pigs, sheep, goats, and chickens, are raised to a lesser extent. Commercial woodlands (excluding sapling-seedling stands) are predominately saw-timber stands, with a lesser proportion of pole-timber stands. Maple farming (for maple syrup) has recently become common among local farmers.

About 24,430 acres of farmland (including cropland, woodlot, and range pasture) and 24,416 acres of forest lie within an 8-mile radius of the plant. There are also 510 acres in urban areas within the same distance. The distribution of forest property in Pike County is similar to that of surrounding counties. Pike County is also typical from the standpoint of productivity. Forests are dominated by a tree cover of white oak, red oak, and hickory, mixed with lesser numbers of maple, ash, pine, and sycamore trees. Very dry or infertile soils are dominated by small stands of pine or black locust trees. Logged areas support scattered young oaks, hickories, and an abundance of brambles. Other subcanopy species vary throughout the area, with sumac, poison ivy, and blackberry being most common.

Local animal species are typical for southern Ohio. The most important species include white-tailed deer, eastern cottontail rabbit, squirrels, muskrats, bullfrogs, mallards and wood ducks, bobwhites, pigeons, and mourning doves. Deer are rather more common on site than off site, presumably because of lower hunting pressure on site. Numerous species of snakes (most commonly the black rat snake and northern black racer), turtles, frogs, and toads are also present. Fish populations in local small streams are typical of headwater-type streams and include carp, shad, bluegill, and various species of minnows and darters. Populations in larger streams (Big Beaver Creek and the Scioto River) are more abundant and diverse and also include various catfish, suckers, sunfish, trout, bass, and bullheads. Examples of state and federally listed plant and animal species that may be expected to inhabit areas within and adjacent to the site boundary are the river otter, eastern woodrat, Indiana bat, badger, rocky skullcap, long-beaked arrowhead, Virginia dayflower, darkeyed junco, kingrail and common tern, although none have been identified within the reservation boundary [2].

The availability, quantity, and quality of groundwater at any location are controlled by the geologic conditions beneath the surface of the land. Sand and gravel deposits in particular store and transmit sizable quantities of water. Clay, silt, and shale can contain as much water per cubic foot as sand and gravel; however, the water is held in pores so small that it generally cannot be transmitted in usable quantities. Water yields from limestone or sandstone depend on the particular nature of the formation being examined (grain size, fractures, joint bedding planes, etc.).

The predominant landform in the site area is the relatively level, broad, filled valley of the preglacial Portsmouth River. The valley is oriented north to south and is bounded on the east and west by ridges or low-lying hills that have been deeply dissected by present and past drainage features. These ridges consist of Mississippian formations of Sunbury and Cuyahoga shales. Another significant landform is the small valley formed by Little Beaver Creek, which flows northwesterly across the middle of the DOE property, just north and east of the main plant area (shown in figure 3).

The hydrogeologic conditions underlying the DOE site are similar to those of the Teays River valley. The shale and sandstone bedrock underlies the entire property and outcrops in the hills along the east and west portions of the facility. This bedrock contains little or no water. The unconsolidated alluvial deposits are the Minford Clays and the Gallia Sand formations. A moderate amount of free water is contained in the gravelly Gallia Sand but is not easily obtainable because of the large percentage of clay mixed in the gravel. The Minford Clays are essentially impermeable except in the weathered surface layers.

Three aquifers or aquifer types can be distinguished at the PORTS site: (1) the bedrock aquifer, consisting of shallow Mississippian shales and sandstones; (2) the Scioto River alluvial aquifer, and (3) other alluvial aquifers. The latter two aquifer types have similar characteristics and properties and can thus be described as a single aquifer system.

An analysis of topographic maps, surface water drainage, and past aerial photos of the site led to the prediction of groundwater divides and an interpretation of groundwater flow directions. In general, groundwater in the northern part of the site flows toward Little Beaver Creek. In the vicinity of X-701B (eastern portion of the site), it flows eastward toward the creek. Little Beaver Creek eventually discharges into Big Beaver Creek. The flow direction at X-616 is westward toward a small, unnamed, intermittent tributary of the Scioto River. Subsurface flow at X-749 is divided between a westward component and an eastward component conforming to the upper reaches of the Big Run drainage basin. The upper tributaries of the Big Run drain the area of X-231B. Groundwater flow in this flat area is probably toward the south (see figure 3).

E. Health Outcome Data

This section identifies the relevant databases; they are evaluated in the Public Health Implications section.

The U.S. EPA's epidemiological database listing U.S. Cancer Mortality Rates and Trends for 1950-1979, was reviewed. The U. S. Centers for Disease Control and Prevention (CDC), National Center for Health Statistics, Office of Analysis and Epidemiology, compiles mortality data for the entire U.S. population on its WONDER (Wide-ranging ONline Data for Epidemiologic Research) database for the years 1979 to 1991. Assessors took a detailed look at all causes of death for Pike, Ross, and Scioto counties in Ohio. The Ohio Department of Health publishes an annual report of vital statistics.

ATSDR also collected community health outcome data from the following sources:

  • NCI Report "Cancer in Populations Living Near Nuclear Facilities. Volume 2: Individual Facilities Before and After Startup" (1953-1984)

  • Pike County vital statistics were provided by the Vital Statistics Registrar for the Pike County Ohio Board of Health.

  • Ohio Department of Health (ODH) Report "Cancer Mortality Rates in Ohio, 1986 - 88"

  • Ohio Cancer Mortality Data for 1987 to 1992 from ODH

  • National Institute for Occupational Safety & Health (NIOSH) Study "Mortality Among Uranium Enrichment Workers" January 1987 Comprehensive Epidemiologic Data Resource (CEDR) by U.S. Department of Energy, Assistant Secretary for Environment, Safety and Health (August, 1993):

  • Residents living near PORTS completed a cancer survey (1994) for the area surrounding the facility.

  • Boston University staff contacted health and legal practitioners who were reported to have noticed excess health outcomes in the community around PORTS or to possess possible sources of health outcome data.

  • The Pike County Public Health Nurse was contacted about any possible health outcomes noticed, at the request of residents.

  • An oncologist at the Medical Center Hospital in Chillicothe, OH was contacted, at the request of residents, about any health outcomes noticed.

COMMUNITY HEALTH CONCERNS

Residents living in the vicinity of the PORTS are concerned that their health has been adversely impacted by operations at the plant. During a preliminary visit to the area in September 1992, ATSDR staff members met area residents in a town meeting. Numerous concerns expressed during the site visits and during several public meetings and availability sessions include the following:

1) skin rashes, resembling patches of sunburn;
2) chronic lung disease, requiring the use of oxygen;
3) nodules on heads and backs that looked like cysts or boils;
4) degeneration of connective and skeletal tissue not associated with arthritis or osteoporosis;
5) spotty discolorations on teeth;
6) birth abnormalities, such as webbed hands and ear-folds and
7) excessive numbers of cancers in children and cancers in general.

There was general concern over spills of uranium hexafluoride on site during the 1960s and 1970s. Also, there were concerns about worker exposure to polychlorinated biphenyls (PCBs), trichloroethylene (TCE), uranium hexafluoride (UF6), asbestos, and hydrogen fluoride (HF).

A more extensive list of collected community concerns from site visits, public meetings, public availability sessions, newspaper articles, letters, phone calls and meetings with residents are addressed in the Community Health Concern Evaluation section on page 44.


ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

A. On-Site Contamination

The Portsmouth Gaseous Diffusion Plant (PORTS) is not on the National Priorities List (NPL). There have been no remedial investigations (RIs) or feasibility studies (FSs) conducted under CERCLA, and no CERCLA RI/FSs are pending. Radioactive and hazardous mixed wastes have been stored on site, and there are waste burial areas and settling ponds. On-site contamination appears to limited to ground water. No contaminants were identified in surface soils, accessible sediment, or surface water at levels that could adversely affect public health.

Soil Contamination

On-site soils are sampled for Uranium, Technetium-99, and non-radioactive Chromium. Data was reviewed up to and including that published in the 1992 Environmental Report. Concentrations of these materials on-site, did not significantly differ from concentrations off-site. There is no indication of any Uranium, Technetium-99 or Chromium deposition on or off-site, away from process buildings.

Table 5. On-Site Soil Contamination

Contaminant Minimum Concentration Maximum ConcentrationA Background Concentration in Soils for the State of OhioB
Total Uranium 3.0 mg/kg 13.5 mg/kg 3-11 mg/kg
Technetium-99 5.9 pCi/g 9.0 pCi/g NA
Chromium 9.2 mg/kg 129 mg/kg 10-500 mg/kg
A. Not directly adjacent to Process Buildings
B. Elemental Concentrations in Soils and Other Surficial Materials of the United States; H. Shacklette and J. Boerngen; USGS paper # 1270, 1984.

Groundwater Contamination

Leaking process lines have resulted in releases of trichloroethylene (TCE) to a shallow aquifer. The comprehensive groundwater monitoring evaluation of the plant site has identified plumes of uranium, technetium-99 and TCE [3]. Table 6, on the following page, lists the highest concentrations of identified contaminants on site and their location.

Table 6. On-Site Groundwater Contamination

Contaminant Highest Concentration1 Comparison Value Location
Trichloroethylene (TCE) neat (pure TCE) 7,000 ppb child (EMEG3)
20,000 ppb adult (EMEG3)
Below X-701B Process Lines
Uranium (soluble salts) 100 ppb or 33 pCi/L 26 pCi/L (MCL2) Below X-749 Unit
Technetium-99 5,000 pCi/L 3790 pCi/L (MCL2) Below X-705 Building
1. RCRA COMPREHENSIVE GROUND-WATER MONITORING EVALUATION of USDOE PORTSMOUTH GASEOUS DIFFUSION PLANT, Piketon, Ohio. Dated July 15, 1993; U.S.EPA I.D. # OH7 890 008 983

2. MCL: The Maximum Contaminant Level allowed by EPA for public drinking water sources servicing over 20 households. These concentrations assume chronic ingestion of 2 liters of water per day over 70 years.

3. EMEG: ATSDR guidance level for environmental media..

Although the highest concentrations for the above contaminants are much higher than drinking water standards just below the leaky process lines, the extent of contamination is limited to the alluvial Minford Clay and Gallia Sand Aquifer, which is under the center of the site. This aquifer discharges to Little Beaver Creek and Big Run Creek before contaminated groundwater can migrate off site. No concentrations in Little Beaver or Big Run Creeks exceed any health-based comparison values [4].

Gaseous Radionuclide and Fluoride Emissions

On March 7, 1978, a cylinder containing uranium hexafluoride (UF6) ruptured and released 10 tons of the material onto a paved area [5]. Several other cylinders have had small valve leaks, which released unmeasurable quantities of UF6 [6]. The UF6 would not have escaped off-site, because it is a solid below 56C (133F). This incident is further discussed on page 57 in question 13.

Gaseous radionuclide and fluoride emissions from the purge cascade vents, the cold recovery and wet air evacuation vents, and the X-345 high assay sampling area vent are currently sampled continuously by systems developed and built by the PORTS plant laboratory. Together, these vents account for virtually all of the radionuclide emissions and most of the fluoride emissions from PORTS. The continuous vent samplers use an isokinetic probe to draw a flow-proportional sample of the vent stream through two small alumina traps in series. The primary sample traps are replaced weekly, and the secondary traps are replaced quarterly.

The radionuclides known to be present are the three natural uranium isotopes (234U, 235U, and 238U); two trace impurities from recycled uranium (236U and technetium 99Tc); and equilibrium concentrations of short-lived uranium daughters. Fluorides are present as various reactive fluoride gases, including UF6 and HF. Alumina from the sampler is analyzed for total uranium, 235U, technetium, and total fluorides. The 235U/total uranium ratio (the assay) and process data are used to calculate the fractions of 234U and 236U in the emissions. Because of their short half-lives, uranium daughter emissions cannot be reliably measured in weekly samples and are assumed to be in equilibrium with their parent nuclides. The uranium daughters included in the equilibrium calculations are 234Th, 231Th, and 234mPa (Protactinium) [7].

The bulk of the fluorides emitted from PORTS is released from the cascade vents and from burning coal in the X-600 steam plant. Coal contains trace concentrations of natural fluoride compounds, of which about half are reduced to gaseous fluorides during combustion. PORTS representatives estimate fluoride emissions from the steam plant from the total tons of coal purchased and literature values of average fluoride content. Vents also allow fluoride piping and processing equipment to be vented for repair and maintenance at a safe distance from plant work areas. Estimated emissions from these vents are included in the total fluoride emissions but have no significant effect on the final figure. Fluoride releases have not been constant over the life of the plant, and environmental monitor data is not available prior to 1974.

The purge cascades use gaseous diffusion continuously to separate UF6 from light gases (primarily air) that have leaked into or otherwise entered the process. The UF6 is returned to the main cascade and the light gases are passed through activated alumina traps to remove residual traces of UF6 and other pollutants before being sampled and vented to the atmosphere. PORTS uses two purge cascades, the side purge cascade and the top purge cascade. Both cascades are exhausted by dedicated air jets (Tjet and Sjet) or a standby air jet (Ejet) that can be connected temporarily by a valve to replace either of the regular air jets. All three jets are sampled by separate continuous samplers. The purge cascades account for the bulk of the routine radionuclide emissions from the cascade [8].

The cold recovery and wet air evacuation systems are maintenance support systems in the X-330 and X-333 process buildings (see Figure 2). Cold recovery systems are used to evacuate gases from cascade cells that must be opened for maintenance. Refrigerated cold traps are used to freeze out UF6, and non-condensable light gases are passed through sodium fluoride traps and vented to the atmosphere. After maintenance, the wet air evacuation systems evacuate outside (wet) air through alumina traps before the cell is returned to service. In X-330, both systems exhaust through a common roof vent with a single sampler. In X-333, the two systems have separate roof vents and samplers. These systems are normally minor sources of emissions [9].

Another emission source is the continuous vent sampler system, in building X-345, where cylinders of enriched UF6 are heated and sampled for quality control. To prevent sample mixing, the sampling manifold must be purged and evacuated after each set of samples. The evacuated gases are cold trapped to recover residual uranium and then vented through alumina traps. In addition, there is a suction device (a "gulper") behind the sample cylinders to collect any small releases during cylinder disconnects. The combined exhaust from both systems is sampled by a single continuous sampler [10].

The enrichment cascade is divided into six control areas, each of which has its own control room and seal exhaust station. The seal exhaust stations collect and vent air leaked into the system from inside the shaft seals between the cascade compressors and their motors. The air passes through activated alumina traps, vacuum pumps, and oil traps (i.e., mist eliminators) before being vented. The seal exhaust station in X-333 (Area 1) was equipped with a continuous sampler on an experimental basis in early 1989. As a result of the success of this sampler, continuous samplers were installed on the remaining five seal exhaust vents in late 1991; they began operating the first week of 1992 [11].

In addition to the continuous samplers, other systems monitor the emissions from the cascade vents. Process control is based on real-time information provided by ionization-chamber-type instruments called "space recorders." Space recorders have limited sensitivity and cannot distinguish between uranium and technetium emissions, but they can provide qualitative information adequate for operating purposes. The space recorders are checked (every 4 hours on the purge cascades) by 5-L (1.3-gal) grab samples that are analyzed on a priority basis. Grab samples provide only limited information, however, and some data suggest that the technetium concentrations in the grab samples may be biased high under some conditions. The grab samples are also less sensitive than the weekly samples, which represent several thousand liters of sampled vent gases. The PORTS plant laboratory is currently developing a modification of the continuous sampler that would use a pair of gamma detectors to measure uranium accumulation in the traps in real time. Major problems at present are background drift and a need to know the assay of the uranium emissions released [12].

Criteria Air Pollutant Emissions

PORTS operates numerous small sources of criteria (or conventional) air pollutants, but only three of them are significant. These are the 3 coal-fired boilers at the X-600 steam plant, which supply the plant with 125-psi steam for process and building heat. Typically, only one or two boilers operate at a time, depending on outside temperatures. The boilers operate under permits issued by the Ohio Environmental Protection Agency (OEPA), with limits on opacity, particulates, and sulfur dioxide (SO2). The permits also specify the required emission monitoring for these parameters, and results are reported to the Ohio EPA quarterly.

Opacity and particulate emissions are controlled by electrostatic precipitators on each of the boilers. Opacity is measured continuously and recorded on 24-hour circular charts and monthly strip charts. Opacity is a measure of the darkness of a plume of smoke and is determined by shining a beam of light through the smoke and measuring the percentage of light that passes through. Environmental regulations specify a limit of 20% opacity, which is equivalent to a light haze. Opacity is also used as a daily indicator of particulate emissions, which require time-consuming and difficult stack sampling to measure directly. Such stack sampling (and 100% compliance with particulate limitations) is required to renew the Ohio EPA operating permits every 3 years. PORTS performed this sampling in late 1986 and early 1987 and received renewed operating permits for all three boilers in 1987, 1990 and 1993.

Sulfur dioxide emissions are calculated from coal analyses rather than from direct measurement. All coal deliveries to the plant are sampled and analyzed for calorific value (BTU [British thermal units] per pound), ash content, and sulfur content. The quarterly reports to the Ohio EPA summarize the amount of coal purchased, the average results of the coal analyses, and the calculated rate of SO2 emission along with the opacity data.

PORTS formerly operated another potential SO2 emission source, the X-616 liquid effluent treatment facility. This facility used liquid SO2, which was purchased in 1-ton cylinders, to treat blowdown water from the plant's cooling towers. Hexavalent chromium was formerly used as a corrosion inhibitor in the recirculating cooling water (RAW) systems. The S02 was injected into the incoming blowdown water to reduce the hexavalent chromium to the less toxic trivalent form. No odor of S02 was normally present at the facility, indicating that essentially all of the S02 was consumed in the reaction. PORTS switched from chromate-based corrosion inhibitors to phosphate-based inhibitors. The last system was converted to phosphates in June 1991. The X-616 facility was shut down on April 9, 1992, with the concurrence of the OEPA.

In addition to the pollutants discussed previously, all fossil-fuel-burning equipment emits nitrogen oxides (NOX) and carbon monoxide (CO). The primary source of NOX and CO at PORTS is the steam plant itself. There are also minor contributions of these pollutants from oil-fired heaters, stationary diesel engines, and mobile sources (e.g., cars and trucks) [13].

Particulate Radionuclide Emissions

PORTS recovers uranium from decontamination solutions used on site and uses solid chemical absorbents to control trace radionuclide emissions. Both operations can generate radioactive airborne particles. To protect both workers and the environment, these materials are handled inside filtered gloveboxes. All gloveboxes exhaust through high-efficiency particulate air (HEPA) filters, which have a specified minimum capture efficiency of 99.97%.

Two gloveboxes are considered important enough to have particulate samplers on their exhausts. The X-345 glovebox was originally used for sampling of uranium oxide produced by the uranium recovery operations. For several years, the glove box's only use has been the repackaging of occasional damaged oxide containers. The X-744G glovebox was installed to allow sampling (as needed) of used alumina or other absorbent material. Both gloveboxes receive very little use and consequently have never shown any significant emissions.

Other Airborne Emissions

Another hazardous air pollutant emitted from PORTS is asbestos from the renovation or demolition of plant facilities. Asbestos emissions are controlled to the level of "no visible emissions" by a system of work practices supervised by the plant's Industrial Hygiene and Health Physics Department. The amount of asbestos removed and disposed of is reported to the Ohio EPA quarterly and would only be a health concern for those working with the material.

PORTS purchases liquid chlorine (Cl2) for water treatment. Chlorine is used to disinfect incoming well water, outgoing treated sewage, and recirculating cooling water (RAW). Very little chlorine, if any, is lost to the air from the incoming water or the sewage, but the RAW is effectively air stripped in the cooling towers. PORTS assumes that all chlorine fed to the RAW system is lost to the air and that all chlorine used elsewhere is entirely consumed.

The gaseous diffusion process generates a large amount of heat that must be removed by the plant cooling system. Because water is a nuclear moderator and is also chemically reactive with UF6, it would be unsafe to cool the process directly with the RAW. Therefore, PORTS uses a two-stage system with Freon 114 as the intermediate coolant. Inevitably, given the size of the cooling system, a considerable amount of the Freon leaks into the cascade or the RAW or directly into the air. A thermal degrader destroys the Freon that enters the cascade, but Freon emissions from the RAW system and from building ventilation are uncontrollable. Estimates of Freon emissions are currently based on purchased amounts.

PORTS used TCE for degreasing for nearly 30 years. The use of TCE was phased out in favor of the less toxic l,l,l-Trichloroethane (TCA) during the mid-1980's. PORTS is now in the process of shifting away from TCA in favor of water-based solvents. Historically both organic and inorganic solvents were used to degrease equipment prior to maintenance or repair. Freon 113 is used for final cleaning of parts (piping, gaskets, etc.) that might come in contact with UF6 process gas. Both solvents are usually assumed to evaporate completely. TCA is recycled until it evaporates. Small amounts of other hydrocarbon solvents are also used, and these have been lumped together and assumed to evaporate completely also. The inorganic solvents used at PORTS (primarily nitric and citric acids) do not contribute significantly to air emissions.

Toxic Chemical Release Inventory

Under Section 313 of the Emergency Planning and Community Right-to-Know Act (SARA, Title III), manufacturers are required to report to the EPA annually if they have released into the environment (routinely or accidentally) any of more than 300 toxic chemicals. Section 313 authorizes EPA to maintain the data in a computerized database that is known as the Toxic Chemical Release Inventory. Manufacturing facilities (as defined in the Standard Industrial Classification codes 20-39) that have 10 or more full-time employees and that manufacture or use a Title III-listed chemical in an amount greater than its specified threshold for manufacture, import, processing, or other use during any calendar year are required to estimate their annual releases of such toxic chemicals into the air, water, and land. The database is available to federal and state government officials and to the public.

PORTS is a large-point-source emitter of various gases (i.e., an emitter from stacks and vents). Table 7 lists the Toxic Release Inventory (TRI) for PORTS. Table 8 lists emissions from other manufacturers in Pike County, Ohio. ATSDR representatives searched the Toxic Chemical Release Inventory database for toxic chemical releases to the soil, water, and air from facilities in Pike County, Ohio, including the Portsmouth Gaseous Diffusion Plant, for the reporting years 1987 through 1990.

Table 7. Toxic Release Inventory (tons) Portsmouth Gaseous Diffusion Plant [14]

Chemical 1987 1988 1989 1990
Air Air Air Air
Methanol

0.25

2.0

4.9

6.6

Hydrogen Fluoride

11.5

14.1

12.0

NR

Chromium

0.7

NR

NR

NR

Chromium Compounds

NR

0.9

1.15

1.4

Trichloroethylene

2.6

NR

NR

NR

Nitric Acid

0.25

0

0

0

Chlorine

24.1

0

61

91

1,1,1-Trichloroethane

47

32

10

4.8

Ethylene Glycol

NR

5.6

0.9

NR

Freon 113

NR

10.3

8

10

Acetone

NR

4.5

4.0

NR

Zinc Compounds

NR

NR

NR

0.6

NR means "Not Reported"


Table 8. Toxic Release Inventory (tons) Other Manufacturers in Pike County, Ohio [15]

Chemical
1987
1988
1989
1990
Air Air Air Air
NaphthaleneA 2.1 NR NR NR
DibenzofuranA 0.2 NR NR NR
AnthraceneA 0.05 NR NR NR
ChromiumA 0.15 NR NR NR
CopperA 0.15 NR NR NR
ArsenicA 0.15 NR NR NR
Methyl Isobutyl KetoneB NR NR NR 0.9
TolueneB NR NR NR 2.2
PropyleneB NR NR NR 7.2
MethanolB NR NR NR 2.2
XyleneB NR NR 0.6 2.6
A Southern Wood Piedmont, Waverly, OH
B DWP Corp. DBA Mill's Pride, Waverly, OH
NR means "Not Reported"

B. Off-Site Contamination

Soil, sediment, surface water, ground water and air samples were reviewed. Soil samples found only natural quantities of uranium or other radioactive materials. Off-site ground water samples have not detected any contaminant migration, and regular samples of private residential drinking-water wells have not detected any radioactive contamination or volatile organic materials as of the 1994 PORTS Annual Environmental Report.

The data for off-site air samples is available only for the year 1986 and later. There was no measurable off-site release from the UF6 cylinder rupture that took place on March 7, 1978. ATSDR received the incident report for this accident and all sample documentation [16]. ATSDR staff has determined that not enough material could have reached off-site areas to cause adverse health effects.

On-Site Air Monitoring Stations

Description of Ambient Air Monitoring System

Off-Site Air Monitoring Stations Since 1964, PORTS has maintained a network of permanent on-site and off-site stations to collect ambient air samples continuously. Figures 6 and 7 show the location of current stations in the monitoring network. Airborne fluoride measurements have been reported since 1974.

The particulate filters are collected monthly and counted for gross alpha and beta-gamma loading. If the gross counts exceed plant established limits of 100 disintegrations-per-minute (dpm)alpha or 200 dpm beta-gamma, the filters are analyzed for specific radionuclides. To date, air samples have never exceeded these limits. The treated filters are collected weekly and analyzed for total fluorides. To prevent cross contamination and to simplify handling, the Teflon and treated filters are mounted in separate Teflon filter holders.

Ambient Gaseous Fluorides

Table 9 presents a summary of the highest weekly ambient fluoride in a given year. This table compares average fluorides to the Kentucky and Tennessee state ambient air standards. Although these standards are not legally binding on an Ohio facility, neither the state of Ohio nor the federal EPA has issued standards for ambient gaseous fluorides. Note that only gaseous fluorides are included. The standards exclude particulate fluorides. Kentucky has set a primary (public health) standard at an annual average concentration of 400 µg/m3 (micrograms per cubic meter) and a secondary (public welfare) standard of 1.6 µg/m3. Tennessee has set both primary and secondary standards at 1.6 µg/m3. Table 9 covers fluoride measurements for the years 1986 to 1992.

 

 

Table 9. Highest Weekly Average Fluoride Concentrations (as HF) in Ambient Air for the Years 1986 through 1992

Year Location Concentration (µg/m3) Standard Deviation
Min Max Ave
OFF SITE
1986 A28 0.03 1.42 0.32 0.09
1987 A28 0.02 1.44 0.32 0.27
1988 A12 0.10 3.47 0.69 0.86
1989 A3 0.06 2.31 0.44 0.40
1990 A3 0.06 0.86 0.17 0.16
1991 A3 0.06 0.79 0.20 0.13
1992 A3 0.00 0.77 0.09 0.16
ON SITE
1987 A39 0.285 0.88 0.53 0.24
1988 A40 0.08 3.14 0.97 0.65
1989 A39 0.06 3.75 1.00 0.91
1990 A39 0.01 1.96 0.60 0.43
1991 A39 0.05 3.81 0.44 0.65
1992 A39 0.00 3.33 0.51 0.64
Note: The Kentucky and Tennessee standards for average gaseous fluoride concentrations (1.6 µg/m3) were used as comparison values in the determination of contaminants of concern because of the absence of any federal or state of Ohio standard.

C. Quality Assurance and Quality Control

ATSDR obtained Quality Assurance/Quality Control (QA/QC) summaries from EPA and DOE with respect to environmental monitoring data. No analytical problems were noted in the QA/QC summaries obtained. ATSDR will continue to review data provided by the public.

D. Physical and Other Hazards

No accessible physical hazards were identified at the site.


PATHWAYS ANALYSIS

The process of uranium enrichment and manufacturing intermediates has resulted in releases of toxic materials in the groundwater, surface waters, soil, sediment, and potentially air at PORTS. Rain water percolating through on-site soils and past storage and disposal of wastes has affected groundwater underlying the site.

To determine whether people are exposed to contaminants migrating from a site, ATSDR representatives evaluate the environmental and human components leading to human exposure. An exposure pathway consists of five components: 1) a source of contamination, such as drums or waste pits; 2) an environmental medium in which the contaminants might be present or from which they might migrate, such as groundwater or soil; 3) points of human exposure, such as drinking water wells or work areas; 4) routes of exposure, such as inhalation, ingestion, or dermal absorption; and 5) a potentially exposed population.

A. Completed Exposure Pathways

Only the air pathway was identified as a completed exposure pathway, but not at a level of heath concern. No other completed exposure pathways were identified in the areas for which there is sufficient sampling information to make an exposure determination. An exposure pathway is defined as potential if one or more of the necessary components is missing. In general, the first two components of a completed pathway (a source of contamination and transport through an environmental medium) do not exist for many areas at PORTS. Usually, one or more of the remaining components are missing. Because of the contaminants' isolated locations and security measures at the storage and disposal areas, humans have little opportunity for contact with contamination. In areas with sufficient sampling information, no completed exposure pathways other than air have been identified.

Air Pathway

A completed pathway for hydrogen fluoride was thought to exist in the past, as stated in the ATSDR Public Health Consultation on Fluoride Releases from the Portsmouth Gaseous Diffusion Plant [17]. Since the Ohio Valley is known for a pattern of summer temperature inversions, it was thought that it could cause potentially dangerous levels of air pollutants (e.g., hydrogen fluoride) to build up and not disperse. The review of classified documents from the site revealed that the assumptions of the health consultation were in error, and that hydrogen fluoride is not principally released in a batch process. Measured levels of total fluoride are just above background concentrations for the region and below all health standards. There are also inadvertent releases mentioned in the Annual Environmental Reports, but these have not resulted in any measurable concentrations off-site.

Table 10. Completed Exposure Pathways

Pathway Name Source Media Point of Exposure Route of Exposure Potential Exposed Population Timeframe
HF X-324
X-330
X-333
Air Ambient Air Inhalation Less than 500 within a 2 mile radius of site Past

Surface water is not considered to be a completed pathway, because:

1) Surface water from on-site is not a source of drinking water.
2) No point of exposure to surface water on-site could be identified.
(Note) Even if there were a completed pathway for exposure, the sampling data did not show sufficient contamination, in surface water or fish samples, to represent any threat to public health [18], [19].

Groundwater is not considered a completed pathway, because:
1) The contaminated aquifer is confined on-site, and is not used as a source of drinking water on-site.
2) Past private well surveys have shown no indication of site related contaminants [20].

B. Potential Exposure Pathways

The only potential pathway for human exposure to contaminants appears to be via groundwater.

Groundwater Pathway

Groundwater is used extensively as a source of drinking water by local residents, but supply is seasonal and unreliable. Public water supplies are not available to all people living in the vicinity of the site. Nearly one-third of households in Pike County do not have public water. However, ATSDR could not identify any residents with drinking water wells that are in the same geologic formations or, could be hydrologically downgradient from contaminated groundwater plumes at PORTS [21].

Leaking process lines have resulted in releases of trichloroethylene (TCE) to a shallow alluvial aquifer. These process lines have been out of service since the late 1980s, when PORTS discontinued the bulk use of TCE. This contamination has not migrated off-site and has not affected nor ever been detected in private or public drinking water.

EPA has done a comprehensive groundwater monitoring evaluation of the plant site and identified plumes of uranium, technetium-99 and TCE [22]. Table 7 lists the highest concentrations of identified contaminants in on-site groundwater and their locations. This aquifer is limited in extent to the site and is not used as a source of drinking water. The contaminants are in excess of the Maximum Contaminant Levels (MCLs), set by EPA for public drinking water supplies serving more than 20 households. MCLs are the most stringent requirements for safe drinking water. The worst case concentrations at the seeps are about 30 percent above the MCLs. In accordance with an agreement with EPA, managers at the site have installed a pump and treat facility to remove TCE just upgradient of the outfall into Little Beaver Creek.

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