What's Ahead for the Nation's Depleted Uranium Hexafluoride?
Mary Byrd Davis
In storage yards at the nation's present and former uranium enrichment plants are some 700,000
metric tons of depleted uranium hexafluoride, a toxic product of the uranium enrichment process.
The US Department of Energy (DOE) in April published a Final Programmatic Environmental
Impact Statement for Alternative Strategies for the Long-Term Management and Use of
Depleted Uranium Hexafluoride (FPEIS). The agency's preferred alternative is to begin
converting the inventory "to uranium oxide, uranium metal or a combination of both, while
allowing for use of as much of this inventory as possible." But is "allowing for use" the most
appropriate step? Business interests and Congressional representatives from the areas near the
plants are pressing for a quick decision on conversion in the hope that "the large inventory of
DUF6 [can be converted] into a resource that could be used to spur new industrial activity."(1) The
problem is not entirely in the hands of DOE since a private company, the United States Enrichment Corporation (USEC), is now accumulating its own stock of depleted
uranium hexafluoride (UF6). Here we briefly survey the problem, the range of options, and the prospects.
I. The Problem
Production of UF6
Natural uranium consists of three isotopes, uranium 234, uranium 235, and
uranium 238, approximately 0.0058%, 0.71%, and 99.28% respectively. Uranium
235 unlike uranium 238 is fissile, that is it can sustain a chain reaction.
Light water nuclear power plants (the type in the United States) operate
on fuel containing between 3 and 5% uranium 235 (low-enriched uranium);
nuclear weapons are normally fabricated with uranium containing more than
90% uranium 235. Therefore, before natural uranium can be used in fuel for
light water reactors or for bombs it must be "enriched" in uranium 235.
Enrichment processes transform the natural uranium into two products, enriched uranium with a higher percentage of uranium 235 than natural uranium and depleted
uranium (also known as "tails"), with a lower percentage of uranium 235 than natural uranium. For every kilogram of low-enriched uranium that is produced, five to
ten kilograms of depleted uranium are formed. The standard enrichment processes today are gaseous diffusion and centrifugation. Both use uranium in the form of
UF6. In the United States the depleted uranium that has been created by enrichment is stored as UF6.
The UF6 stock is packaged in carbon steel cylinders. The vast majority has a capacity of 14 tons (12 metric tons). Typically they are 12 feet (3.7 meters) long and 4 feet
(1.2 meters) in diameter and have walls 5/16 of an inch thick. Some smaller cylinders with a capacity of 10 tons (9 metric tons) are also in use.(2)
DOE and its forerunners the Atomic Energy Commission and the Energy, Research, and Development Administration produced approximately 46,422 cylinders
(560,000 metric tons) of depleted UF6. These cylinders are stacked two-high in the open air on gravel or concrete. The K-25 enrichment plant at Oak Ridge, Tennessee
(now no longer in operation) has 4683 of the DOE cylinders; the Paducah, Kentucky, plant, 28,351, and the Portsmouth, Ohio, plant, 13,388.(3)
USEC, the corporation that has taken over uranium enrichment from DOE, has produced and is still producing additional depleted uranium. Between its creation as a
government-owned corporation in July 1993 and its initial sale to private stockholders in July 1998, USEC produced 9186 cylinders (approximately 110,000 metric tons)
of depleted UF6.(4) According to the NRC, USEC estimates that it will generate approximately 84,354 metric tons more of depleted UF6 from October 1, 1997 through
September 30, 2005.(5)
Implementing a May 1998 memorandum between DOE and USEC,(6) DOE assumed title to the 9186 cylinders of depleted UF6 generated by USEC prior to
privatization.(7) Furthermore, in accordance with a June 1998 memorandum between DOE and USEC(8), USEC paid DOE $50 million from its account in the U.S.
Treasury before privatization in return for DOE's assuming "responsibility for disposal of a certain amount of depleted UF(6) generated from operations at the plants
from October 1998 to 2005."(9) This agreement will entail the transfer of 2026 cylinders over six years. Of the cylinders that have been and will be transferred to DOE
under the two memoranda, 8559 will be located at Paducah, 2653 at Portsmouth.(10) If USEC's production estimate of 84,354 metric tons is correct, the company has
yet to announce a decision about what it will do with 56,100 metric tons of depleted UF6.(11)
UF6 is not an ideal storage medium, as it is an unstable, toxic chemical. If UF6 escapes into the atmosphere, it reacts with moisture in the air to form hydrogen fluoride
(HF) and uranyl fluoride (UO2F2). Hydrogen fluoride is a corrosive gas that can cause lung damage or, when inhaled in large quantities, death.(12) Uranyl fluoride is
a soluble compound, toxic from both a chemical and a radiological point of view. If it is inhaled, the uranium, a heavy metal, moves rapidly into the blood. Part is
eliminated in the urine; part is deposited in the kidneys or bones, which it irradiates. In the kidneys the uranium can cause kidney dysfunction or cancer; in the bones,
The cylinders holding depleted uranium produced by DOE date from as far back as the fifties. In some cases, signs of external corrosion appear; in some, container
walls have become thin. Before 1998, seven cylinder breaches (holes) were discovered, five as a result of damage during handling and two, at K-25, as the result of
corrosion from prolonged contact with the ground. All these cylinders were repaired and, if necessary, moved. In 1998, one breach occurred, at K-25, as a result of
A breach in a cylinder does not immediately lead to a significant escape of UF6, however. At ambient temperatures and pressures, UF6 is a crystalline solid similar to
rock salt.(15) Stored cylinders of UF6 contain "solid UF6 in the bottom and UF6 gas at less than atmospheric pressure in the top."(16) DOE cautiously states that the
UF6 is "not readily released . . . following a leak or breach." "When a cylinder is breached, the air reacts with the exposed UF6 solid and iron, resulting in the
formation of a dense plug of uranium and iron compounds. The plug tends to block the breach for a period of time, so that release of uranium compounds and HF gas
occurs very slowly."(17)
In an environmental assessment on the refurbishment of cylinder storage yards at Paducah, DOE states, "A release of gaseous UF6 could occur only if there is a fire
with sufficiently high temperature and duration to heat the solid UF6 to the point where it undergoes sublimation (change from a solid to a gas without ever becoming a
liquid)." DOE continues: "Two initiators, an airplane crash or a fire involving cylinder handling equipment, were identified [in a Process Hazards Analysis]. The
results of the analysis for a gaseous release indicate that the potential for fatality or serious injury to operating personnel exists."(18) UF6 sublimates above 56.4
Celsius (133.5 Fahrenheit). In becoming a gas, the UF6 would expand and force its way out of the cylinder. The reaction of UF6 with the moisture in the air would
be exothermic, that is it would give off heat. Thus the release of a portion of the contents of one cylinder could conceivably cause nearby casks to become sufficiently
hot for their UF6 to sublimate. Criticisms of DOE's current method of storing UF6 include fears of the effect an earthquake might have on cylinder yards.(19) In the
FPEIS, DOE states that "an earthquake which could cause more than slight damage is considered credible (though highly unlikely) only for the Paducah site."(20)
DOE has an active cylinder management program. It is moving cylinders that touch the ground or are too close to one another and improving cylinder yards. About
75% of the cylinders are inspected once every four years; the remainder, those previously stored under substandard conditions or showing corrosion or pitting,
yearly.(21) Cylinders are painted to prevent corrosion, with the assumption that the paint protects the cylinders for ten years. Ultrasonic inspections to measure the
thickness of cylinder walls and valve monitoring and maintenance, including replacing leaking valves at the storage sites, are conducted where DOE finds that they are
USEC has management responsibility for any cylinders that it has not yet turned over to DOE. Furthermore, USEC helps to maintain cylinders that are owned by DOE.
USEC has, in fact, had a "master of service agreement" with DOE according to which DOE has paid USEC for work in the areas of "environmental management,
canister maintenance, and site support services."(23) Since December 1997, DOE has also had a management and integration contract for its overall environmental
management program with Bechtel Jacobs, which works largely through subcontractors. As we go to press, DOE, USEC, and Bechtel Jacobs are negotiating whether
the work that USEC has been doing should stay with USEC or go to subcontractors of Bechtel Jacobs.
DOE maintains that depleted uranium can be stored safely as UF6. However, responding in part in response to concerns of the Defense Nuclear Safety Board, the states
where cylinders are located, and people living near the storage yards, DOE prepared its Programmatic Environmental Impact Statement on management and use of
depleted UF6. The draft version was dated December 1997; the final version, April 1999. USEC, which does not have to be concerned with the NEPA process since it
is a private company, is quietly is looking into options. USEC's Security and Exchange Commission (SEC) filing of December 18, 1998, states, "USEC stores depleted
UF(6) at the plants and continues to evaluate various proposals for its disposition."
II. Management Alternatives
In its FPEIS, DOE considers six approaches:(24)
No action: Continued storage of depleted UF6 at the gaseous diffusion plants;
Long-term storage as UF6: Storage as UF6 cylinders in yards, buildings, or a mine at a consolidated site;
Long-term storage as uranium oxide: Conversion of UF6 to UO2 or U3O8, followed by storage in buildings, belowground vaults, or a mine at a consolidated site.
Use as uranium oxide: Varied potential uses include radiation shielding, dense material applications other than shielding, and light water reactor and advance reactor
fuel cycles. For purposes of this document, DOE assumes that the UF6 would be converted into UO2 and used as the primary shielding in casks for irradiated fuel and
high-level radioactive waste.(25)
Use as uranium metal: Conversion of UF6 to uranium metal. Applications include "existing uses of depleted uranium metal, such as armor-piercing munitions
(penetrators), vehicle armor, and industrial ballasts. Potential new commercial applications" include "energy storage, flywheels and drill collars, well penetrators,
industrial counterweights, and shape charge perforators for the petroleum industry."(26)
Disposal: Conversion of UF6 to an oxide, either UO2 or U3O8, followed by disposal as low-level waste in shallow earthen structures, belowground vaults, or a mine.
In its December, 1998, Annual Report for Lithium Hydroxide and Depleted Uranium Hexafluoride to the state of Ohio, DOE describes plans to test the use of depleted
uranium in forklifts and jack-hammers. Forklifts now use iron counterweights. DOE plans to have a private company retrofit a 5,000 lb. forklift with a depleted
uranium counterweight and to equip a cylinder handler at Paducah with such a weight for test purposes. Optimistically, DOE explains "Forklift truck counterweights
represent a substantial potential market for depleted uranium. In 1994, for example, more than 101,000 diesel and electric powered forklifts were manufactured in the
United States, with an average counterweight of approximately 3,200 pounds. This represents a one-year demand for counterweights of nearly 147,000 metric tons.
The depleted UF6 inventory is approximately 700,000 metric tons, including the fluorine component (p. 9)."
USEC is developing the AVLIS enrichment process, which it hopes to substitute for gaseous diffusion. This process is so selective that it will be able to enrich depleted
UF6. Thus it will make possible the use in reactor fuel of most of the uranium 235 that remains in depleted uranium. DOE only alludes to the use of depleted UF6 in
reactor fuel, but it would be surprising if USEC were not seriously considering the possibility of enriching at least its own depleted material. The company is in the
process of selecting a site for an AVLIS plant and hopes to have the plant in operation by 2007.
AVLIS enriches a feed of uranium metal or metal alloy rather than UF6. Thus any use of depleted UF6 in AVLIS would have to be preceded by conversion of the UF6
to metal. In the AVLIS section of its SEC filing of December 18, 1998, USEC stated that it was "exploring joint development of an alternative UF(6) product conversion
facility with another vendor [other than Cameco or General Electric]." This could refer to the conversion of depleted UF6 into metal for
Institute for Energy and Environmental Research (IEER)
In March 1998 comments on DOE's draft PEIS, Annie Makhijahni and Arjun Makhijahni of IEER ask that depleted uranium be disposed of as transuranic waste in a
deep geological repository. Transuranic waste, according to 40 CFR 191.01 (i) is "waste containing more than 100 nanocuries of alpha-emitting transuranic isotopes,
with half-lives greater than twenty years, per gram of waste." Depleted uranium is not transuranic waste by this definition because it contains no transuranic isotopes
(isotopes of elements higher than uranium on the periodic table). However, in terms of specific activity (radioactivity measured by weight) and mode of decay, depleted
uranium fits. Thus, as far as its potential effect on the environment and human health, it is the equivalent of a transuranic and should be so treated. All the more so, in
that the daughters of uranium 238 will build up over the years and cause the waste to become increasingly radioactive.
IEER also suggests that depleted uranium be blended with surplus high-enriched uranium for reactor fuel. This could involve only a small portion of the stock.(28)
III. No perfect answer
All of the approaches have drawbacks, although disposal in a deep geological repository would appear to be the safest option.
No Action or Long-term Storage as UF6
The storage of depleted uranium as UF6, whether at the three plants or at a consolidated site, would not be satisfactory in the long run even if cylinder ruptures could
be entirely avoided. Because of the characteristics of UF6, the cylinder maintenance and surveillance program would have to be continued as long as the UF6 remains
in cylinders. The half life of uranium 238 is 4.5 billion years but , as IEER has pointed out, the useful life of the cylinders is measured in decades.
Conversion for use or Disposal
Methods to convert UF6 into U3O8, UO2, and uranium metal are well established. DOE briefly presents the basic techniques and mentions others still in the process of
development. The long-standing methods are as follows:
Conversion to U3O8: DOE presents a "dry process" in which UF6 is decomposed chemically by means of steam and heat to produce U3O8 and HF. The U3O8 is then
compacted. This process has been used commercially by Cogéma in France since 1984.
Conversion to UO2: The conversion of UF6 to UO2 is a basic step in the production of fuel for light water reactors and is conducted at fuel fabrication plants, which
receive UF6 from the enrichment plants. The UF6 is converted to UO2 powder by a wet process or a dry process. The powder is then compressed into pellets. The wet
processes are based on separation of solid UO2 from an aqueous solution; dry processes on decomposing and reducing the UF6. DOE's wet process, which it calls
"gelation," has not yet gone beyond the stage of "pilot-scale studies"
Conversion to uranium metal: Conversion of UF6 into metal has already taken place at the gaseous diffusion plants to produce uranium metal for defense purposes.
The HEU and the depleted uranium in nuclear warheads, for instance, are in metallic form. The basic conversion process is known as metallothermic reduction: UF6
reacts with hydrogen and magnesium metal to produce uranium metal, anhydrous (without water) HF and magnesium fluoride (MgF2; slag). In the FPEIS DOE
presents the batch process, which is the method used to date, and a new continuous process.(29)
The conversion processes would lead to bulky wastes. Conversion to uranium metal would produce "large quantities" of MgF2, which would be disposed of in a
sanitary landfill or a low-level waste (LLW) disposal facility, depending on the radioactivity and regulations.(30) All of the conversion methods outlined above
produce hydrogen fluoride as a byproduct. This toxic, highly corrosive compound could react with containers holding it to produce a buildup of hydrogen. Long-term
storage of hydrogen fluoride would be more dangerous than long-term storage of UF6. DOE plans to sell the HF, in its aqueous or anhydrous forms, or to combine it
with lime and sell or dispose of the resulting CaF2. Selling could be problematic given the volumes of HF and CaF2 produced (approximately one third of a ton of HF
for each ton of UF6) and the fact that both the HF and CaF2 would be at least slightly contaminated with uranium.(31)
Converting the entire stock of depleted UF6 would also lead to more than 50,000 empty cylinders. The cylinders will increase the already massive problem of how
DOE is to dispose of slightly contaminated scrap.
The conversion processes would have radiological impacts. DOE estimates that the impacts on workers and the general public would be similar for the normal
operation of each of the processes described above. Conversion to U3O8 would result in average radiation exposure of about 300
mrem/yr to workers directly involved
in the process and less than 0.01 mrem/yr to noninvolved workers and members of the public; conversion to UO2,, in less than 340
mrem/yr to involved workers and
less than 0.04 mrem/yr to noninvolved workers and members of the public; conversion to metal, in less than 240
mrem/yr to involved workers and less than 0.03 mrem/yr to noninvolved workers and members of the public. In terms of accidents, the risk is greatest for conversion to U3O8 (assuming that the accidents deemed
likely during specific lengths of time actually occur). The maximum dose that noninvolved workers and the general public could receive is estimated to be 9.2
the various possible accidents all technologies considered, those with the largest impacts would be caused by rupture of a tank containing
HF; a spill from a corroded
cylinder when it is raining; rupture of an ammonia tank; and a fire from a vehicle accident involving three 48G cylinders.(32)
All of the use scenarios carry with them the disadvantage that they necessitate conversion with its drawbacks. The uses that DOE discusses are also problematic
because of the radiological and chemical toxicity of depleted uranium, which would pose risks for workers making and using depleted uranium products and, in certain
circumstances, for the general public.(33)
The manipulation and use of depleted uranium metal is particularly hazardous because of its pyrophoric properties. In a finely divided state, like powder or shavings,
it may burst into flame spontaneously when in contact with air at ambient temperature. In more massive form it could burn in an industrial or vehicle fire. When it
burns--and to a much lesser extent when in massive form it oxidizes slowly at room temperature--it gives off minute particles of uranium oxide. If inhaled, these
particles, which are relatively insoluble, may become stuck in the lungs and irradiate the nearby tissue over a long period of time, provoking lung cancer. They also
contaminate the environment, virtually permanently given the half lives of the uranium isotopes. A penetrator made of depleted uranium metal ignites when it impacts
its target, dispersing up to 70% of its mass in a spray of aerosolized radioactive particles.(34)
That "depleted uranium" is not harmless is illustrated by the contamination at the site of the Starmet Corp., formerly known as Nuclear Metals, Inc., in West Concord,
Massachusetts. Uranium buried in a waste pit at the plant "has reached the groundwater in concentrations up to 3000 times the safe level." Excavating the site would
cost $50 million, a cost that would likely drive Starmet into bankruptcy.(35) Starmet announced in a May 5, 1997 press release that it had received a contract to
demonstrate production aggregate, DUCRETE, which would be mixed with cement for shielding material.(36) DUCRETE is the form in which DOE intends to use U02
for shilding.(37) USEC obtains metal from Starmet for its AVLIS program.
The use of depleted uranium to make casks, whether oxide or metal, does not solve the question of how to get rid of the uranium unless the casks are certified as
packaging for final disposal and can be buried in a repository with their contents inside them. The Nuclear Regulatory Commission (NRC) has not yet certified any
depleted uranium casks.
The reenrichment of depleted uranium would simply produce another batch of depleted uranium, though with a smaller percentage of uranium 235 by weight than the
DOE's naming shallow earthen structures as a possibility for disposal of depleted UF6 would put it into the category of class A low-level radioactive waste. The NRC
stated in the case of a proposed Louisiana enrichment plant that shallow land burial of depleted uranium could result in unacceptably high doses to future
The drawback to the disposal of depleted uranium as transuranic waste is that the long-term integrity of the only US site constructed for such waste, the Waste Isolation
Pilot Project (WIPP) in New Mexico, is open to question.
DOE's management plan during much of the work on the PEIS "was to continue safe storage of the cylinders and, if feasible alternative uses for the depleted uranium
had not been found by 2010, take steps to convert the UF 6 to triuranium octaoxide (U3O8) beginning in the year 2020. The U3O8 . . . would be stored until there was
a determination that all or a portion of the depleted uranium was no longer needed. At that point, the U3O8 would be disposed of as low-level radioactive waste
(LLW). The basis for the plan was to reserve depleted UF 6 for future defense needs and other potentially productive and economically viable purposes."(39)
In the Final Programmatic Environmental Impact Statement, DOE expresses a different point of view. Its preferred alternative strategy is to begin conversion of the
inventory "to uranium oxide, uranium metal or a combination of both, while allowing for use of as much of this inventory as possible. Conversion to oxide for use or
long-term storage would begin as soon as practicable, with conversion to metal occurring only if uses are identified."(40)
"The time period for which activities were assessed for all strategies was approximately 40 years: generally 10 years for siting, design, and construction of any required
new facilities; about 26 years for operations; and, when appropriate, about 4 years for monitoring."(41) No matter what alternative is followed, the UF6 would be
stored in place until at least 2008.(42)
After DOE has selected a strategy and described it in a Record of Decision published in the Federal Register, it will identify, the FPEIS says, "the specific sites and
technologies necessary to carry out the strategy." The sites and technologies will be the subject of additional Environmental Impact Statements or Environmental
The FPEIS represents long-term planning, one of three tiers of DOE's depleted UF6 program. The second is cylinder management. The third is "identifying markets
and uses for depleted uranium products." In 1998, for this third tier, DOE focused on organizing and initiating depleted uranium products and marketing development
efforts. Its activities in 1998 in addition to work on specific products including establishing a website about the Depleted UF6 Management Program,
http://www.ead.anl.gov/uranium.html, and holding meetings with industry in order to provide the foundation for a program aimed at developing commercial uses for
Two of the site nominations have already been determined. Congress, under the influence of legislators who feared that their respective districts would lose jobs
because of the privatization of the uranium enrichment establishment passed a bill requiring that "all amounts accrued on the books of the United States enrichment
corporation for the disposition of depleted uranium hexafluoride will be used to commence construction of, not later than January 31, 2004, and to operate, an onsite
facility at each of the gaseous diffusion plants at Paducah, Kentucky, and Portsmouth, Ohio, to treat and recycle depleted uranium hexafluoride consistent with the
National Environmental Policy Act.(45)
The funds accrued are payments required by the Energy Policy Act of 1992 from US utilities who have bought enrichment services from DOE and USEC.(46) They are
paid to and held by USEC and amount to approximately $400 million.
With the President's signature in July 1998, the bill became Public Law 105-204. March 4, 1999 DOE issued a Request for Expressions of Interest for a Depleted
Uranium Hexafluoride Integrated Solution Conversion Contract and Near-Term Demonstrations, and March 12 it issued an Initial Plan for the Conversion of Depleted
Uranium Hexafluoride as required by the law. The plan calls for the construction of one or two facilities at or near the gaseous diffusion plants. It indicates that
funding in addition to that provided by PL 105-204 will be needed and that DOE wants to cooperate with the private sector in developing a cost-effective disposal
program. Rep. Ted Strickland (D. Ohio) questioned William D. Magwood, director of DOE's office of nuclear energy, about the plan and subsequently received a letter
from Magwood saying that DOE does intend to build two facilities and expects to release a final plan in May. Bidding on construction and operation will follow shortly
thereafter. DOE's Initial Plan states that construction could start as early as 2002.(47) A Final Plan for the Conversion of Depleted Uranium Hexafluoride was to be
issued in May, apparently before DOE's announcement of its Records of Decision on management alternatives, which is to appear in 1999 also.
Meanwhile, encouraged by DOE, academic institutions in Kentucky and Ohio are seeking funding to carry out research on the commercial uses of depleted UF6. The
University of Kentucky has committed $2.2 million towards a $5 million research and public education center at Paducah Community college and has requested the
balance of the $5 million from the state of Kentucky and the Department of Energy. Ohio's Technology Action Fund administered by the Ohio Department of
Development has committed $250,000 to a Midwest Institute for Depleted Uranium Solutions
(MIDUS), planned by Ohio State University (OSU). For it, OSU is
seeking $100 million from DOE over 10 years, $10 million for the first year. The University of Kentucky, which will administer the Paducah project, and OSU will
work in partnership. Ohio University will also be a partner in the research according to an article in The Columbus Dispatch. Robert Snyder, chairman of OSU's
Department of Materials Science and Engineering, says "'We need a year to 18 months to make the first cut among the technologies so we can decide which companies
to bring on as partners."(48)
The timetable outlined in an Initial Plan scarcely leaves room for the orderly process of identifying sites and technologies and subjecting them to additional
Environmental Impact Statements or Environmental Assessments. Concerned citizens will need to monitor closely the rapidly developing plans for the management of
depleted UF6 and be ready to exert pressure as needed.
The question of what to do with the depleted uranium is, however, intractable. Although storage is generally preferable to use, a perfect way to manage existing stocks
is not in sight. The difficulty of the problem should make us reflect that there is an answer to the question of future stocks: eliminate them by simply not producing
Office of Nuclear Energy, Science, and Technology, US Department of Energy, Initial Plan for
the Conversion of Depleted Uranium Hexafluoride As Required by Public Law 105-204, p. 2.
2 Office of Nuclear Energy, Science, and Technology, US Department of Energy, Programmatic
Environmental Impact Statement for Alternative Strategies for the Long-Term Management and
Use of Depleted Uranium Hexafluoride, DOE/EIS-02-69, April 1999, I, S-3; The containers
commonly used for transport and storage of UF6 feed, product, and tails are 48-inch diameter 10-
and 14-ton (9- and 13-metric ton [sic]) heavy-wall cylinders; thin-wall cylinders of the same sizes;
and 30-in diameter 2.5-ton (2.3 metric ton) cylinders The 10- and 14-ton heavy-wall cylinders
and the 2.5-ton cylinders, all of which have a wall thickness of 5/8 inch, are approved by DOT and
the NRC for shipment of UF6. The 10- and 14-ton (9- and 13-ton) thin-wall cylinders, which have
a wall thickness of 5/16 in., are normally used for storage of depleted UF6 (Safety Analysis
Report, Paducah Gaseous Diffusion Plant, Paducah, Kentucky, prepared by Lockheed Martin
Energy Systems, KY-EM-174, vol.1, p. 2-141 and 2-142).
3 FPEIS, I, p. S-2. As of 1996, the uranium in DOE's depleted UF6 amounted to 95.2% of DOE's
total inventory of depleted uranium. The remainder was in the form of metals, oxides, nitrates,
fluorides, and other compounds (DOE, Taking Stock: A Look at the Opportunities and
Challenges Posed by Inventories from the Cold War Era, DOE/EM-0275, Jan. 1996, p. 39).
DOE will ship up to 3,800 metric tons of depleted and slightly enriched uranium metal and
powder from its shut-down Field Materials Production Center at Fernald, Ohio, to the Portsmouth
Gaseous Diffusion Plant for storage starting in June 1999 ("Uranium Headed to Piketon," Daily
Times, April 16, 1999). The Fernald plant is being decontaminated.
4 Initial Plan, p. 4; the tonnage is estimated using the ratio of 12:1 in DOE's figures on DOE
cylinders and metric tons.
5 US Nuclear Regulatory Commission, Compliance Evaluation Report for the Renewal of
Certificate of Compliance GDP-2, Revision 1, United States Enrichment Corporation,
Portsmouth Gaseous Diffusion Plant, Docket 70-7002, January 1999, p. 43.
6 Memorandum of Agreement Relating to Depleted Uranium Generated Prior to the Privatization
7 Nuclear Fuel, July 13, 1998, p. 29; Initial Plan, p. 4.
8 Memorandum of Agreement Relating to Depleted Uranium
(FPEIS, I, 6-1 for titles).
9 Nuclear Fuel, July 13,1998, p. 29; SEC 1-A , p. 20.
10 The dates are confusing. Privatization occurred in July 1998. According to the Initial Plan,
USEC actually paid DOE $66 million, not $50 million, in 1998; Initial Plan, p. 5.
11 Compliance, p. 43; DOE stores 4683 DOE-generated cylinders of depleted UF6 at three sites at
Oak Ridge's K-25 Plant. The K-1066-K yard (K Yard), which is constructed of concrete and
crushed stone, has historically been poorly drained, yet it holds 2945 cylinders. The K-1066-E
Yard (E Yard), built of concrete, holds 1716 cylinders. Only 22 cylinders are stored at K-1066-L
Yard (L Yard). Because of the drainage problem at K Yard, DOE inspects cylinders stored there
yearly. The agency plans to construct a new yard at K-25 and to move all the site's cylinders after
1999. At the Paducah plant, DOE stores 28,351 DOE-generated cylinders in 13 storage yards
totaling 13 acres. Nine of the yards have gravel bases. They will be rebuilt with concrete bases.
One yard, C-745-F, is on the foundation of a former building. Three have new concrete bases
(FPEIS, I, 3-5). Also at Paducah, in C-745-C, C-745-Q and C-745-R are at least 6,600 USEC-generated cylinders (C-745-C also contains DOE-generated UF6). These three yards have gravel
bases. The Q and R yards will be rebuilt with concrete bases after the gravel-based yards storing
DOE-generated cylinders have been reconstructed; and cylinders from the C yard will be moved to
them (FPEIS, I, 6-1). At Portsmouth DOE stores 13,388 cylinders that it generated. At least
2800 USEC-generated cylinders are located in X-745-G yard just outside what is known as the
Portsmouth Uranium Enrichment Complex. The yard is paved; but aisles are not four-feet wide.
According to the Final PEIS, restacking of the cylinders onto concrete saddles is planned.
12 FPEIS, I, p. S-3.
13 DOE/EA/1118, p.c. on Paducah storage yard. (Environmental Assessment, Refurbishment of
Uranium Hexafluoride Cylinder Storage Yards C-745-K, L, M, N, and P and Construction of a
New Uranium Hexafluoride Cylinder Storage Yard (C-745-T) at the Paducah Gaseous Diffusion
Plant, Paducah, Kentucky, July, 1996).
14 FPEIS, II, B-3, B-4; D-3.
15 FPEIS, II, 0-3.
16 FPEIS, I, S-3.
17 FPEIS, I, 1-6.
18 DOE/EA/1118, p. 4-14.
19 FPEIS, III, 3-33 and 3-138, for example.
20 FPEIS, III-33.
21 FPEIS, II, D-3.
22 FPEIS, II, D-2 to 3.
23 Nuclear Fuel, Jan. 25, 1999, p. 7.
24 FPEIS, 1, S-11.
25 FPEIS, I, 2-11, 2-12.
26 FPEIS, 1, 2-21 and 2-22.
27 In May 1995, USEC signed a $2 million contract with Molten Metal Technology
(MMT) for a
demonstration of the application of MMT's Catalytic Extraction Process to the conversion of
depleted UF6 into hydrogen fluoride and uranium oxide or metal. MMT operated a pilot plant at
Oak Ridge between December 1995 and mid 1996. According to USEC the pilot was a success
but USEC never entered into an agreement with MMT for use of its process at a commercial level,
doubtless at least in part because MMT had financial and political problems. It filed for
protection from its creditors under Chapter 11 of the US Bankruptcy Code in December 1997, and
the House Commerce Committee investigated the relationship between a $33 million contract
with DOE and contributions to the Democratic Party (Nuclear Fuel, December 15, 1997, p. 15).
28 Comments of IEER on the draft PEIS of Dec. 1997, March 1998.
29 FPEIS, II, F-11 F-13.
30 FPEIS, I, 2-15.
31 FPEIS, II, Fll-F14; Memorandum to Lance Hughes and Diane Curran from Annie Makhijani
and Arjun Makhijani, 30 July 1993.
32 DOE bases the potential environmental impact of the various alternatives primarily on
information in an Engineering Analysis Report compiled for DOE by Lawrence Livermore
National Laboratory (LLNL) and completed in September 1997. A brief summary of the report is
included as Appendix O in volume two of FPEIS. The Engineering Analysis Report contains
thirteen Engineering Data Input Reports giving the layouts for facilities, descriptions of processes,
estimates of wastes and emissions, estimates of resources and workers needed, hazard
assessments, accident scenarios and transportation information for each of thirteen options and
suboptions; FPEIS, II, F-16 F-35.
33 The term "depleted" is in a sense a misnomer. Depleted uranium contains less uranium 235 by
weight than does natural uranium (around 0.20% instead of 0.71%). However, it is nevertheless,
radioactive, since uranium 235 contributes little to the total radioactivity of natural uranium. Both
natural uranium and depleted uranium emit alpha particles and weak gamma rays. One gram of
uranium undergoes 25,205 alpha disintegrations a second; one gram of depleted uranium
undergoes 14,273 such disintegrations. The difference is largely due to the difference in the
uranium 234 component of the two uraniums. Furthermore, uranium 238 decays into thorium
234, which decays into protactinium 234, which decays into uranium 234 and so on. The thorium
and protactinium emit energetic beta particles and gamma rays. The half life of uranium 238 is
4.47 billion years. Thus, for all practical purposes, uranium 238 can be said never to cease giving
off alpha particles and decaying into beta and gamma emitters (Leonard A. Dietz, Letter to the
New York Times; June 29, 1997).
34 Military Toxic Project; Depleted Uranium Citizens' Network, Radioactive Battlefields of the
1990s, January 16, 1996, p. 3.
35 Scott Allen, "Concord Firm Halts Cleanup," The Boston Globe, 17 May 1999.
36 The press release is summarized by Peter Diehl in his list of materials on depleted uranium,
distributed from http://antenna.nl/wise/uranium/index.html.
37 FPEIS, II, H2-H3.
38 Nuclear Regulatory Commission, Final Environmental Impact Statement for the Construction
and Operation of the Claiborne Enrichment Center, Homer Louisiana, NUREG-1484, Vol. 1,
August 1994. Cited in Science for Democratic Action Vol. 5 no. 2.
39 FPEIS 1, pp. S-3 and S-4.
40 FPEIS, 1, p. 2-1.
41 FPEIS, I, p. S-6.
42 FPEIS, II, D-1.
43 FPEIS, I, p. 3-7.
44 Downloaded from website, http://www.ne.doe.gov, May 27, 1999; DOE Annual Report for
Lithium Hydroxide and Depleted Uranium Hexafluoride, December 19, 1998, p. 3, 10-11.
45 Quoted in FPEIS, II, p. N-1.
46 Nuclear Fuel, June 29, 1998, p. 3.
47 Terri Fowler, "Piketon Facility Draws Concern," Daily Times, March, 1999 [undated photocopy
supplied by PRESS].
48 "Paducah College Might Be Site for Reclaiming Uranium," Lexington Herald-Leader, April
18, 1999, p. C5; David Lore, "OSU Project Gains Support from State," The Columbus Dispatch,
April 22, 1999; Bill Murphy, Paducah Community College, Personal Communication.
This report was made possible by financial support from The John Merck Fund.
copyright © 2000 by Mary Byrd Davis
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