Radioactive Waste Rising in Tank
By LINDA ASHTON
06:22 AM ET 09/28/99
YAKIMA, Wash. (AP) - A vast waste tank at the Hanford nuclear reservation that
used to ``burp'' gas has a new problem: The radioactive goop inside has risen like bread
dough. While the development within the million-gallon tank has provoked concerns about a
possible explosion or contamination, managers at the Department of Energy site in
south-central Washington say both scenarios are unlikely.
``The chance of explosion is very low,'' said Rick Raymond, the project manager
for the contractor, Lockheed Martin Hanford. Still, ``any time you have a situation where
you're trapping gas faster than releasing it, it's an unacceptable situation and needs to
be dealt with in an urgent manner.''
The radioactive waste in Tank SY-101 is a byproduct of the process used to
extract plutonium from uranium irradiated at Hanford's now-defunct nuclear reactors. The
tank, less than 10 miles from the Columbia River near Richland, contains cesium and
decaying organic materials that generate hydrogen, nitrogen, nitrous oxide and ammonia.
The tank became notorious in the late 1980s and early '90s as Hanford's
``burping'' tank because it released thousands of cubic feet of gas every three months or
so. If an ignition source had been present, the flammable gases could have exploded. A
mixer pump installed in 1993 took care of the problem by allowing the continuous escape of
small amounts of gas. But it also created a new problem no one expected - without the
periodic releases of huge amounts of gas, bubbles began to build up in the meringue-like
crust floating in the liquid waste.
The crust began to thicken and grow. It is now about 10 feet thick in a tank
just over 38 feet tall. The top of the crust is 26 inches from the top of the tank,
although it was 2 inches higher in May, when Hanford managers began releasing gas at the
same rate it is produced.
While the possibility exists that the waste could spill over and breach the
tank, the five-eighths-inch-thick steel welds on the double-shell tank should prevent that
from happening, Raymond said. Beginning in late October or early November, Lockheed Martin
Hanford will begin pumping out the tank, diluting 300,000 gallons of the radioactive brew
as it is transferred to another tank, and then diluting the 700,000 gallons still in
SY-101 with water. That should be a permanent fix, said Craig Groendyke, manager for the
SY-101 project for the Energy Department's Office of River Protection.
Hanford was established in 1943 as part of the Manhattan Project to build the
atomic bomb. Plutonium for nuclear weapons was produced at the site until 1986.
The site has 54 million gallons of radioactive waste stored in 149 aging
single-shell tanks, 67 of which have leaked. Newer tanks, such as SY-101, have two shells,
and none has leaked.
