Research
Highlights...
 
 

Melinda Hamilton cleans up concrete with little critters. See below.

 

Remains of the nuclear fuel that was severely damaged in 1986 at Chornobyl Unit 4 still lie in large masses within the shelter built after the accident. In the form of dust, chunks, and solidified lava, the fuel has the potential to initiate uncontrolled fission reactions when exposed to water that accumulates inside the shelter. Occasionally, high neutron readings detected by monitoring equipment used in the shelter for more than a decade suggest that may be the case.
 

Chornobyl nuclear power plant

To confirm whether the high neutron readings are caused by increasing fission reactions in the fuel debris, the result of faulty detection equipment, or other detection anomalies in the monitoring equipment, U.S. experts designed and built a new neutron monitoring system for the shelter. The system was recently installed by Ukrainian technicians and underwent a series of operational tests by a team of scientists from DOE’s Pacific Northwest National Laboratory performing work for DOE’s Office of International Nuclear Safety and Cooperation.
 

A close-up view of the Chornobyl shelter

“The equipment performed very well during post-installation testing,” said Bob Scherpelz, a Pacific Northwest health physicist. “The Ukrainians are comfortable with the new system and expect that it will provide the measurements needed to better understand the nuclear safety conditions in the shelter.”

The system is now measuring the gamma and neutron radiation fields in six locations throughout the shelter. It’s designed to provide the data necessary to interpret correctly the cause of any future unusual neutron count rates. Possibilities for high neutron count rates detected by the previous system included moisture-damaged equipment cables and shifts in the neutron energy spectrum caused by water. The new system will either verify or rule out these possibilities.

The project is part of a major U.S. effort to improve the safety of Soviet-designed nuclear power plants. Other laboratories involved in international nuclear safety activities are Argonne National Laboratory, Oak Ridge National Laboratory, Lawrence Livermore National Laboratory, Brookhaven National Laboratory, Sandia National Laboratories, and Savannah River Ecology Laboratory.

Submitted by Pacific Northwest National Laboratory
 
 
 

Sometimes it seems like bugs are eating everything—goodies from our picnics, prize-winning taters from our gardens, forgotten leftovers in the back of the fridge—and now scientists are putting those appetites to good use, with bugs that eat the concrete in our buildings.

Melinda Hamilton, a biologist at DOE’s Idaho National Engineering and Environmental Laboratory, is leading a team of researchers who are using microbes to remove contaminated layers from concrete surfaces through a natural degradation process.

Hamilton’s team coats contaminated concrete surfaces with naturally occurring microbes and slathers them with a tasty broth of sulfur—their favorite nutrient. By controlling the humidity in the room (think Mississippi in August), the microbes have everything they need to go to work. The microbial byproduct—corrosive bug poop—is sulfuric acid. The acid etches the concrete surface, loosening the contaminated layer.  Test trials have removed as much as 10 mm in 12 months. Lowering the humidity kills the microbes, then scientists vacuum the dust off the walls, floors, and ceiling and dispose of it.

“I’ve been working with these little critters for eight years,” says Hamilton. She started out studying how soil microbiology affects the stability of buried cement waste forms. Hamilton quickly realized that the microbial degradation problem could be put to good use actually treating contaminated concrete. This technology offers significant improvements in treatment costs and personnel safety over current methods.

British Nuclear Fuels Limited (BNFL) has been working with the INEEL and hopes to apply the technology at nuclear facilities worldwide. The INEEL and BNFL are planning a full scale demonstration at Sellafield in the UK. “I’ve been to England several times to help get everything set up. It’s been fun,” says Hamilton. 

Submitted by Idaho National Engineering and Environmental Laboratory