Uranium Encapsulation
Process Receives Patent
The following news release was posted
on the DU E-Mail list recently, and while CADU would welcome any process
which makes DU safe in storage and disposal, we feel it could raise
serious concerns if the encapsulation process is used as an excuse
to use DU for more civilian uses. DU is a dangerous substance and
should not be used for any purpose in which a situation may arise
in which it could burn up. We hope this new process doesn't give the
green light to more dangerous 'recycling' of DU.
UPTON, NY Scientists at the US. Department
of Energy's Brookhaven National Laboratory have been awarded US. patent
number 6,030,549 for inventing a process for encapsulating depleted
uranium oxides in thermoplastic polymers. The process converts depleted
uranium to a form that is both stable and safe for long-term disposal.
The encapsulated uranium could also have several useful applications,
including the production of radiation shielding and counter weights
for aeroplanes, helicopters and ships.
Depleted uranium (DU) is a by-product of enriching uranium ore to
make fuel for nuclear reactors. Storing DU requires labour-intensive
and costly maintenance. The Brookhaven Lab process uses uranium oxide
powder, a more stable, but dispersible compound, which is converted
from the reactive form through chemical processing and combined with
a thermoplastic binder. The final product can be formed into shapes
and is cooled to form a dense solid.
"By creating safe, secondary end-use products from these materials,
we are addressing health and safety, environmental protection, and
waste reduction issues," says Paul Kalb, the Senior Research
Engineer who is leading this work for Brookhavenıs Environmental Research
and Technology Division.
BNFL's patented process for encapsulation requires simultaneous heating
and mixing of depleted uranium powders and non-biodegradable thermoplastic
polymers such as polyethylene or polypropylene. Virgin or recycled
polymers can be used. The result is a homogeneous mixture of depleted
uranium and molten thermoplastic polymer, which can be moulded into
any shape.
Tests performed by the Brookhaven scientists reveal that the new material,
composed of anywhere from 10 to 90 percent depleted uranium by weight,
is strong and durable. And because it is largely impermeable to water,
it does not leach radioactive material.
The heavy material can be moulded to form counterweights/ballast for
use in aeroplanes, helicopters, ships, missiles, flywheels, armour,
and projectiles.
Because of the density of uranium, the product is also an excellent
shield against gamma radiation. The presence of hydrogen in the plastic
makes it an effective shield against neutron radiation as well. And
since the product has a much lower percentage of fissionable uranium
(U-235) compared with natural uranium ore, the levels of residual
radioactivity are very low.
The material could therefore be useful in the construction of storage
vaults and casks for radioactive materials or in providing protection
for workers and the public at particle accelerator beam stops and
targets.
"We are currently working with the Brookhaven Office of Technology
Transfer to identify potential industrial partners and opportunities
for commercial development," says Kalb.
The research was funded by the US. Department of Energy.
The US. Department of Energy's Brookhaven National Laboratory creates
and operates major facilities available to university, industrial
and government personnel for basic and applied research in the physical,
biomedical and environmental sciences and in selected energy technologies.
The Laboratory is operated by Brookhaven Science Associates, a not-for-profit
research management company, under contract with the US. Department
of Energy.
