Bot Handles Nuke Waste
Way back in 1943, the Department of Energy set up
nine nuclear reactors at the Hanford Site
( www.hanford.gov) in the desert of southeastern
Washington. The reactors were used to generate
plutonium for atomic weapons from WWII through the
Cold War. Although the reactors were shut down in 1987,
the 586 square mile facility is still the home of billions of
gallons of liquid waste, and millions of tons of solid
radioactive materials. The stuff is stored in underground
tanks, 16 of which — unfortunately — are old single-shell
tanks that are prone to leaking and must be drained
before they cause serious trouble.
This isn’t the kind of thing you want to do with a
sump pump and a garden hose, and the process is made
more difficult by the relatively narrow 12 inch diameter
pipe that’s available to access the contents. However, a
solution apparently has been devised by Washington River
Protection Solutions ( www.wrpstoc.com), a DoE contractor. The fix involves replacing the 12 inch riser with a 42 inch
one, allowing a robotic arm — known as the Mobile Arm Retrieval System, or MARS — to be installed inside. They are
beginning with a tank known as C-107, where the bot will use a water cannon to move waste towards a pump which will
suck the gunk out at rates ranging from 85 to 1,000 gallons per hour, depending on the type of waste.
According to WRPS, this will allow the 247,000 gallons to be removed quickly enough to avoid exposing workers to
any more than about 40 millirems per hour, keeping them within the administrative limit of 500 millirems per year. A
tougher nut to crack will be C-111 which contains a stubborn crust of waste that has fended off attacks with a high
pressure sprayer. But, one step at a time ...
Artist’s rendition of the Hanford tankbot.
AUV Combines Propulsion Schemes
Until recently, there have been essentially two types of autonomous
underwater vehicles (AUVs): relatively fast-moving, propeller-driven units
that can carry a good-sized load of instruments but are limited to stints of
only a few days’ operation; and “gliders” which can operate for months
at a time but are slow and carry a limited payload. But a new seabot
called Tethys combines the best of both these worlds. In high-speed mode,
it can travel at about 2. 25 mph (1 m/sec) which is about quadruple the
speed of most gliders. It can also drop into hover mode, allowing it to
remain in operation for a matter of weeks. Tethys is the work of the
Monterey Bay Aquarium Research Institute ( www.mbari.org) which has
been working on it for about four years. Back in October, the first one was
successfully tested in Monterey Bay, equipped to study phytoplankton
blooms. It is hoped that the design will prove to be inexpensive enough for
wide adoption in a variety of seagoing research and monitoring. The
original Tethys, by the way, was a Greek aquatic goddess, daughter of
Uranus and Gaia. She was both sister and wife of Oceanus, but we won’t
worry about that for now. SV
MBARI researchers tow Tethys behind
a small boat in Moss Landing Harbor.
Todd Walsh© 2010 MBARI.
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