[Federal Register Volume 60, Number 93 (Monday, May 15, 1995)]
[Notices]
[Pages 25893-25894]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-11870]
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DEFENSE NUCLEAR FACILITIES SAFETY BOARD
[Recommendation 95-1]
Improved Safety of Cylinders Containing Depleted Uranium
AGENCY: Defense Nuclear Facilities Safety Board
ACTION: Notice; recommendation.
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SUMMARY: The Defense Nuclear Facilities Safety Board has made a
recommendation to the Secretary of Energy pursuant to 42 U.S.C. 2286a
concerning improved safety of cylinders containing depleted uranium.
The Board requests public comments on this recommendation.
DATES: Comments, data, views, or arguments concerning this
recommendation are due on or before June 14, 1995.
ADDRESSES: Send comments, data, views, or arguments concerning this
recommendation to: Defense Nuclear Facilities Safety Board, 625 Indiana
Avenue, NW., Suite 700, Washington, DC 20004.
FOR FURTHER INFORMATION CONTACT:
Kenneth M. Pusateri or Carol C. Morgan at the address above or
telephone (202) 208-6400.
John T. Conway,
Chairman.
The three large gaseous diffusion plants that were operated by the
Department of Energy (DOE) and its predecessors produced enriched
uranium, some for defense use and some for incorporation into nuclear
fuel for civilian reactors in the United States and other countries. In
the course of isotope separation, most of the uranium ended up as the
part depleted in U-235, designated as ``tails'' or ``tailings''.
Enriched uranium at all desired assays was simultaneously extracted
from the [[Page 25894]] plants, for all purposes, and so no amount of
tails can be identified as related to enrichment solely for either
defense or civilian purposes. Most of all uranium ever mined in the
United States or imported into the United States remains in tails at
the gaseous diffusion plants. These tails are stored onsite at the
three plants in large steel containers, normally termed ``cylinders'',
as the chemical compound UF6.
Members of the staff of the Defense Nuclear Facilities Safety Board
recently had an opportunity to visit the gaseous diffusion plants, to
follow up on information that had been obtained on safety of storage of
the tails. A short report documenting the results of their review is
attached. It was found that DOE has approximately 50,000 cylinders in
outdoor storage at the three diffusion plants, containing more than
500,000 metric tons of UF6. Poor maintenance and storage
conditions, combined with mechanical damage suffered during handling,
have led to corrosion and subsequent breaching of several of these
carbon steel cylinders.
Cylinders have surface coatings (paint) of varying quality and
integrity, which in a large number of cases is severely degraded.
Cylinders are kept outdoors, some stacked on pads and some directly on
the ground. Some older cylinders have been in storage in excess of
forty years. Although general external corrosion seems to increase with
time, handling damage and localized corrosion attributable to
electrolytic attack appear to be more important factors in
deterioration.
The corrosion-resistant coatings have not been maintained, leaving
the vast majority of cylinders vulnerable to localized corrosion.
Visual inspections have shown abundant pitting and crevic corrosion of
the cylinders, as well as galvanic attack near bronze valves and plugs.
Since neither localized corrosion rates nor the extent of existing
defects in the cylinders are well known or well understood, it is
uncertain how many cylinders may be expected to fail in the near
future. DOE and MMES (Martin-Marietta Energy Systems) are attempting to
evaluate the extent of the erosion rates and their consequences;
results are very preliminary, but they indicate that more than 1,000
cylinders have a potential to breach before the year 2020 of no
remedial actions are taken, with the result that their components of
more than 10,000 tons of uranium could become accessible to release to
the environment.
In section 1016 of Public Law 102-486 (October 24, 1992), Congress
directed the Department of Energy to provide within one year a uranium
inventory study that would include among other matters recommendations
for the future use and disposition of inventories of all Government-
owned uranium or uranium equivalents, including depleted tailings. The
Department has not yet complied with this requirement, presumably at
least in part because the matters addressed by Congressional action are
very comprehensive and require extensive decisions on future courses of
action.
It is clear to the Board that directions developed in response to
section 1016 of Public Law 102-486 will affect the long-term future of
the vast inventory of depleted uranium tails. However, the very size of
that inventory means that no matter what actions may be taken, they
will require a long time to consumate, with deterioration of the
cylinders continuing all the while.
To protect against the dispersal of large amounts of uranium to
soil and ground water in years to come, an early start to remedial
action should be planned and then instituted. The alternative could be
a massive problem with extraordinary financial costs.
Therefore, the Board recommends that:
1. An early program be started to renew the protective coating of
cylinders containing the tails from the historic production of enriched
uranium.
2. The possibility of additional measures be explored, to protect
these cylinders from the damaging effects of exposure to the elements,
as well as any additional handling that may be called for.
3. A study be instituted to determine whether a more suitable
chemical form should be selected for long-term storage of the depleted
uranium.
The Board designated Mr. Steven Krahn as its principal staff member
for discussions with those in DOE whom you may designate to act on this
recommendation and matters that may arise concerning it.
John T. Conway,
Chairman.
[FR Doc. 95-11870 Filed 5-12-95; 8:45 am]
BILLING CODE 3670-01-M
