Rock safe for nuclear waste, study shows - KINCARDINE
therecord.com: Pat Halpin - November 27, 2008http://news.therecord.com/News/Local/article/450280
Results from bore-hole drilling support the case for burying nuclear waste deep in the earth at the Bruce Power nuclear site, according to Ontario Power Generation scientists.
The drilling shows a strong, stable rock that hasn't cracked or folded under stress over the last 450 million years, the scientists said.
The rock would provide multiple natural barriers for storing low- and intermediate-level nuclear waste, they said.
The waste would be placed in caverns deep below the site, said Mark Jensen of Ontario Power Generation, the manager of geoscience for what is known as the deep geologic repository project.
"What is particularly exciting is the fact that the core has been such extremely good quality and has allowed us to collect the samples to do the laboratory experiments to demonstrate the suitability of the site," Jensen said.
The four solid cylinders of rock retrieved through bore-hole drilling have given geologists their first chance in 50 years to see the rock under the Bruce Power site, where the first reactors were commissioned in the 1970s.
The proposed storage facility would be 680 metres below ground in Cobourg formation limestone, the name of a 450-million-year-old layer of rock.
This is 20 metres deeper than originally proposed, said Richard Heystee, the project's manager of repository engineering. The slight increase in depth would put the repository in a spot that will allow the best construction and natural shielding, he said.
Long-term underground storage would be for low- and intermediate-level nuclear waste now stored in containers above ground.
This waste includes incinerated paper and cleaning materials, compacted waste and chopped-up generator parts from refurbishment projects at Bruce and Ontario Power Generation's sites.
The lowest-level radiation will reduce to background levels in 400 to 500 years, said Marie Wilson, a spokesperson for the electricity company.
A "tiny" percentage of the material will take tens of thousands of years to return to background levels of radiation, she said.
Next month, Ontario Power Generation is to give the Canadian Nuclear Safety Commission an update on plans for the deep geologic repository. So far, the information from drilling and other tests indicates that the conditions under the Bruce site are what investigators expected, Jensen said.
"Certainly, the picture that's emerging is a very positive one," he said.
The proposed repository, with walls of bare rock, would be deeper than the bottom of Lake Huron and 580 metres below drinking-water supplies.
The repository would not be used for high-level nuclear waste.
This waste, composed of used fuel bundles from reactors, is stored in water-filled bays and in heavily shielded above-ground containers.
New Mexico has been using underground storage for some nuclear waste for 10 years and Sweden for 20.
Ontario Power Generation hopes to start construction of the repository in 2012 and have it in operation by 2017.