The Oak Ridger (TN); Section: State News; November 21, 1997
Ed Yarmak cannot be bothered by the cold. He gives it away by wearing a flowered Hawaiian shirt on what most in East Tennessee would consider a blustery November day. In Yarmak's business, cold is good.
A registered civil engineer, he freezes the ground for a living. He might have never imagined it, but the Department of Energy wanted to use his company's expertise in the more temperate climate of Oak Ridge.
Yarmak works for Arctic Foundations, an Alaskan company that pioneered what it calls a cryogenic barrier.
The Department of Energy hired the company to test cryogenic barriers as a possible method for neutralizing buried radioactive waste at a Superfund site.
The company's founder, Erwin Long, developed the technology to keep the soil frozen around the foundations of buildings in the Alaskan tundra. The constant freezing and thawing of the soil by season can cause foundations to slump in only a matter of years. Freezing the soil maintains the stability of the foundation and saves money on constant repairs.
DOE offered Arctic Foundations a project unlike any other the company had tried -- freezing the soils around a pond that once stored the cooling water from a nuclear reactor. The Environmental Protection Agency, which is responsible for monitoring the cleanup of Superfund sites, is also funding the project. Both agencies shared the bill with Arctic Foundations.
The project began last year at the Homogeneous Reactor Experiment at Oak Ridge National Laboratory. Last summer, Yarmak set out to build a frozen barrier around the 316,000-gallon pond, which contains fission products, principally cesium-137 and strontium-90.
Arctic Foundations, at a cost of about $1 million, has successfully created a barrier of frozen soil around the pond. Yarmak has measured temperatures of about 10 degrees Fahrenheit in the soil forming the barrier.
The cryogenic barrier will not freeze the entire pond, Yarmak explained, it will simply prevent the movement of water through the contaminated area and thus stabilize the contaminants.
Building the barrier involved a blend of Yarmak's engineering skills and the environmental know-how of people such as Elizabeth Phillips, DOE's project manager for the cryogenic barrier demonstration.
Phillips and her team first identified the borders of the old pond by characterizing the contamination in the ground. Then, Yarmak installed "thermoprobes" around the rim of the old pond at a depth of 30 feet, spaced 6 feet apart.
Thermoprobes are the workhorse of this experiment. When the air is cool enough, the thermoprobes operate passively, allowing the cooler air to pull refrigerant down into the soil. In warmer weather, mechanical energy is needed to drive the refrigerant into the soil.
The thermoprobes are constantly pulling an environmentally safe refrigerant, R-40a, from a pair of electrically powered condensing units. The refrigerant circulates at a temperature of about minus 30 degrees Celsius.
The entire pond area is covered with a 6-inch layer of polystyrene for insulation, and a reflective coating was sprayed on top of that to decrease heat absorption.
The freezing of the pond began in September, and Yarmak is taking constant measurements of the soil temperature at and around the probes. Each probes will basically form a frozen circle around itself. Eventually, Yarmak explained, all of the circles will be concentric, and a barrier is formed.
At this point, Yarmak has confirmed temperatures at and below 10 degrees Fahrenheit around the probes.
A series of tests conducted by the EPA will confirm the completeness of the barrier, Phillips said. DOE must be assured that the frozen barrier can keep water from washing contaminants out of the pond, she added. The environmental regulators will inject water with tracers on the outside of the barrier and see if it can pass through.
Phillips pointed out several advantages she has noticed about the project thus far.
First, it is cheap. The project cost about $1 million, she said, and the operating cost for the entire system is about $30 per day.
Second, it is environmentally friendly. The system constantly recycles the refrigerant and produces little or no waste, she said.
"Most of the things that looked like road blocks on this project actually turned out to be bumps in the road," Phillips said.
The tall tubes sticking out of the ground are thermoprobes. Arctic Foundations, an Alaskan company, is using the thermoprobes to freeze soil around a pond at Oak Ridge National Laboratory containing low-level radioactive contaminants from the former Homogeneous Reactor Experiment's cooling water. The frozen barrier, if it passes certain tests, can keep contaminants from moving out of the pond. ORNL photo by Lynn Freeny.
Mark Newbold Neal, Oak Ridger staff
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