Originally created 02/11/00

Buildup finishes SRS unit



Savannah River Site faces a lengthy shutdown of a plant crucial in the treatment of some radioactive liquid waste at the federal nuclear-weapons site.

Officials stopped one of the site's two operating evaporators in early January after they discovered a buildup of silicate, or fine bits of glass, in the unit.

The evaporators are used to reduce the site's volume of radioactive liquid waste by evaporating water from it.

Without the unit, SRS officials will have to take measures to ensure that there is enough space in the site's 49 waste tanks to accommodate waste normally evaporated, according to reports issued by the Defense Nuclear Facilities Safety Board.

But a site spokesman said the shutdown should not cause the site to run out of tank space or fail to meet requirements to treat its liquid waste.

"We have the time to do it," said Dean Campbell, a spokesman for SRS contractor Westinghouse Savannah River Co. "How much time, we don't know. We think we're good for a year or two."

To preserve tank space, SRS workers can transfer waste from tank to tank, Mr. Campbell said. In addition, other SRS plants can take steps to reduce the amount of waste they create, he said.

A new, third evaporator, scheduled to begin operations later this month, also will help alleviate the strain created by the shutdown, Mr. Campbell said. The site's only other evaporator is operating as usual, he said.

The silicate is a problem because it could clog the pipes shuttling waste to and from the closed evaporator, Mr. Campbell said. The silicate also causes radioactive uranium to build up in the unit, which in theory could lead to a dangerous "criticality," or chain reaction.

Tests showed that the closed evaporator was operating within criticality-safety limits and was in no danger of causing a reaction, Mr. Campbell said.

The evaporator, "2H," was used to reduce the volume of waste coming from the site's Defense Waste Processing Facility. That plant mixes liquid waste with fine sand, then heats the mixture into a radioactive glass suitable for long-term disposal.

SRS scientists suspect that the silicate came from the Defense Waste Processing Facility, because the fine glass is a byproduct of that plant's operation, Mr. Campbell said. But site officials still must perform an investigation to determine whether that hunch is correct, he said.

The investigation might not be completed until May, Mr. Campbell said. Fixing the problem will take even longer, he said.

"We're not talking weeks; we're talking months," he said. "We want to make sure we understand it fully before we try to fix it, because we don't want the fix to make it worse. We want to be sure that we can do it."

Reach Brandon Haddock at (706) 823-3409.