64

from this building was significant and probably occurred

over a number of years. For example, in 1986 while

upgrading an unfiltered storm water line leading to

Outfall K015, a subcontractor discovered a large volume

of TCE during an excavation. It is not known how

long this release had been occurring, and the quantity

of TCE released was never determined. Normal

operations presented numerous possibilities for TCE

releases in addition to those that have been documented.

For example, TCE releases are likely to have been

associated with C-720 compressor pit operations, as

evidenced in part by the existence of the southwest

TCE plume.

Interviews with past workers confirmed the accepted

practice of disposal of TCE down building drains not

only in C-400, but also at many other process and

support facilities on site. This practice occurred from

the early Plant operations through the 1970s. Workers

also confirmed that TCE was periodically dumped onto

the ground at locations near numerous process and

support buildings and during cleaning operations in the

switchyards. There was apparently a belief that the

material would evaporate quickly and cause no harm to

the environment.

The outdoor storage and placement of contaminated

waste and scrap that began in the late 1950s (e.g., Drum

Mountain and scrap yards) has continuously contributed

to the spread of contamination through surface water

runoff. Contaminants settled in onsite ditches and

streams. As a result, in the late 1980s efforts were

undertaken to characterize and plan for remedial

measures to address these contaminants. Limited

removal and access controls were established in the

1990s. The Phase I Oversight investigation provided

additional characterization of the contaminants in streams

and ditches in the vicinity of the Plant.

From the beginning of PGDP operations, the C615 sewage treatment plant treated sanitary wastewater

(sewage and sink wastes) from process and support

buildings. Radiological components of treated water

caused the sewage sludge to be contaminated with

uranium. Subsequently, this material was unknowingly

spread at various locations at the site, creating

contamination control problems. In 1977, the C-616

wastewater treatment plant came on line. Major liquid

effluent streams that feed into the North-South Diversion

Ditch were then routed by a lift station to the 616 facility,

resulting in a significant improvement in water quality

in local streams.

 The major component of liquid process waste

during early Plant operations was the recirculating

cooling wateróapproximately 500,000 gallons per day,

with a 20 ppm concentration of chromium. An

additional 80,000 gallons per day of cooling and

scrubber tower water contained soluble fluorides. The

cooling water was pumped to Little Bayou. At one

time, the Little Bayou was a dead stream in parts and

was actually colored yellow by the chromium from the

cooling water. In response to changing Federal

requirements for pollution control, the use of chromium

in cooling water was phased out.

4.4 Atmospheric Releases of

Radioactivity and Fluorine/

Fluorides

ÿ Stack Emissions

ÿ Accidental Releases

ÿ Diffuse and Fugitive Emissions

ÿ Planned Emissions

Radioactive and fluorine/fluoride air emissions to

the atmosphere began with startup in 1952 and have

continued to the present from USEC operations

regulated by NRC. The air emissions from the site

were from process stacks, diffuse and fugitive emission

sources, accidental releases, and a limited number of

planned releases.

Stack Emissions

The site did not perform stack monitoring until the

mid-1970s, so the actual quantities of radionuclides

released to the environment from routine operations

before that time are unknown. From 1959 to 1974, the

air emission reports consisted of ambient air monitoring.

Drum Mountain
65

Starting in mid-1960, continuous ambient air samples

were taken at four locations at the perimeter fence and

were analyzed for alpha and beta activity to provide

input for estimation of annual ambient air concentrations.

In 1961, four additional ambient continuous air samplers

were installed one mile outside the perimeter fence.

Since stack emissions were not measured from 1952 to

1974, the Health Physics and Hygiene Department

estimated emissions based on Plant operations.

Interviews indicated that the estimates were probably

within a factor of two but could be off by as much as a

factor of five. It was not clear whether accidents that

occurred during this period were considered in the

emission estimates.

The first environmental report indicating stack

emissions of uranium and technetium were prepared in

1976 for the 1975 calendar year. Environmental reports

for the years after 1975 also reported annual discharges

to the atmosphere based on stack measurements.

The site, using available information, estimated that

approximately 60,000 kg of uranium was released to

the atmosphere between 1952 and 1990. Of the total,

approximately 75 percent was estimated to have been

released before 1965. Most of the estimated releases

were attributed to the C-410 feed plant and the C-340

metals plant. C-410 was shut down in 1962, reactivated

in 1968, and finally shut down in 1977; C-340 was first

shut down in 1964, reactivated in 1968, and finally

shut down in October 1973. When these plants were

shut down, estimated air emissions from the site were

greatly decreased. The calculations and methods for

these estimates could not be located during this

investigation.

The release of fluorides is tied closely to releases

of uranium. Airborne releases of UF6

 hydrolyze with

the water vapor in air to form HF. Routine releases

and leaks of this material have resulted in deep etching

of glass windows in a number of process buildings at

the site. If the form of the uranium releases were known

for the listed estimated uranium emissions, the amounts

of fluoride released could be estimated. Since

approximately 75 percent of uranium emissions were

thought to have been released before 1965, it is probable

that significant fluoride emissions occurred during the

same period.

From 1959 to 1990, the air emission reports

consisted of ambient air monitoring results for fluorides.

Starting in mid-1960, the continuous ambient gaseous

air samples at the four perimeter fence locations were

analyzed for gaseous fluorides to support estimates of

annual ambient air concentrations. Then, in 1961, the

four additional ambient continuous air samplers one mile

outside the perimeter fence were used. However, actual

stack monitoring of fluoride emissions did not occur

until the mid-1970s. The first environmental reporting

of fluorine stack emissions that was found was for 1986

emissions; only limited information was found for stack

emissions of fluoride prior to 1986. For the period

1986 through 1990, annual discharges to the atmosphere

were reported in annual emission reports based on stack

measurements.

Accidental Releases

A number of accidental releases to the atmosphere

have occurred at PGDP. This Office of Oversight

investigation examined several lists of accidents. One

of these lists, associated with UF6

 releases from

cylinders, identified 15 accidents that released more than

50 pounds of UF6

. Another listing identified about 300

material releases (most of them accidental) from July

1, 1952, to July 1, 1972. These included releases to

the atmosphere and some discharges to water. Sixtynine (excluding routine stack emissions) were probable

airborne releases of more than 10 pounds of uranium

each. No evidence could be found that any of the

accidental releases were analyzed using a meteorological

model for assessing whether there were any significant

acute doses to the public.

From 1960 to 1974, heavy reliance was placed on

ambient air samples for assessing impact on the public.

However, ambient air samples were not always available,

and they only measure plumes at ground level. Lofted

plumes might not be measured, depending on the

meteorological conditions. Plume lofting is expected during

accidental releases of UF6

, since the reaction between the

UF6 and water vapor releases heat. The expected plume

lofting was observed during two accidental releases on

May 20, 1958. An attempt was made to sample the

plumes downwind from the Plant. The first plume was

observed to intersect the ground, while the second plume

remained elevated. In addition, based on the results of a

limited set of measurements, the statement was made that

established MPCs were not exceeded for this release. This

conclusion is probably valid; however, such conclusions

are only generally valid for a well designed field test run

under ideal conditions where peak concentrations can be

observed. During the second set of measurements, the

plume was elevated, and only the maximum concentration

at the ground near the Plant and under the elevated plume

was reported. In this case, the peak concentrations in the

plume were probably not observed.
66

In addition to accidental releases of uranium, a

number of accidental releases of HF occurred. For

example, an analysis was performed in 1975 to explain

high gaseous fluoride readings in the ambient air

samples. In this occurrence, system failures in the feed

plant were attributed to the high readings. Other

accidental or unplanned releases have also occurred.

For example, several former and current workers

interviewed reported blue flames 10 inches high in the

classified landfill after a heavy rain.

Diffuse and Fugitive Emissions

Diffuse and fugitive emissions were generally not

calculated for the site from 1952 through 1990. A limited

set of data exists for releases during the mid-1950s from

some processes, such as uranium metal pickling,

smoking ash receivers, and drum dryer exhaust.

Workplace air samplers and contamination on roofs and

ground in the site area point to the occurrence of

unmonitored releases. One example is the C-404

Holding Pond. Uranium-contaminated water was

originally piped to the pond, and in 1957 the pond was

turned into a solid waste burial area. A ramp was later

constructed to reduce dust emissions from the area.

After the mid-1960s, the ambient air samplers could

have reflected some air concentration contributions to

diffuse and fugitive emissions. However, no modeling

studies were performed to evaluate how those samples

might represent these emissions. Also, only low volume

samples were taken. This Oversight investigation found

no evidence that the performance of the low volume

ambient air sampler network was ever evaluated under

a variety of wind and weather conditions. There was

no evidence that diffuse and fugitive emissions were

substantively included in release inventories and

subsequent public dose calculations. Also, even though

diffuse emissions of transuranics would have occurred

during pulverizing of the feed plant receiver ash, no

estimates of these emissions were found.

Diffuse and fugitive emissions of fluorides were

not calculated for the site from 1952 through 1990. In

addition, the investigation team did not have sufficient

information to estimate releases of fluorides using the

limited set of data for uranium releases during the mid1950s. However, as discussed under UF4

 and metal

production (see Section 3.2.3), the release of fluoride

from the production of UF4

 was the probable cause of

ecological damage in the areas around C-340.

Planned Releases

Four planned atmospheric releases of UF6 occurred

at PGDP: two 4.4 kg releases in 1955 and two 0.68 kg

releases in 1974. These releases were designed to model

plume behavior from a surface release and were

followed by an additional series of tests where

approximately 160 grams of UF6 was released at ground

level directly into the atmosphere. Finally, six releases

occurred in the 1975-1976 timeframe, involving a total

of approximately 1 kg of UF6.

As described in Section 3.2.2, there is some evidence

that planned releases occurred when preparing the

cascade cells for maintenance. Jetting of the cells,

possibly to decrease the concentration of uranium in

the cells, was accomplished by releasing UF6 from vents

on the roofs of the process building. The frequency

and amounts of the releases are unknown. Because a

large quantity of uranium could have been involved,

jetting of the cascades could be a major contributor to

the annual releases. Interviews with the former health

physics manager revealed that contaminants jetted to

the atmosphere in cascade buildings were not factored

into release estimates.

4.5 Environmental Management

Summary

The waste management program at the Plant

reacted to external requirements. The waste

management program that was implemented during the

1980s eventually was able to correct waste activities

that had been inadequately managed for years.

However, large volumes of waste materials accumulated

on site with inadequate characterization for waste

classification and disposal. Controls on waste disposal

practices were not stringent or fully implemented in the

early years of Plant operations, resulting in the creation

of numerous disposal sites at the Plant. Additionally,

based on employee interviews and a review of

procedures and correspondence, it is clear that

radiological waste materials were inappropriately

disposed of in old and sanitary landfills used at the Plant

before the sanitary landfill was permitted by the

Commonwealth of Kentucky. Interviews with current

and former workers identified locations where waste

was discarded around the site from the very early days

of operations. With few exceptions, these locations

correspond to past landfills, scrap yards, lagoons, and

spill sites that have been identified as SWMUs as part