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	When nuclear bomb designer Tuck gave a 
talk in Auckland a quarter-century ago, he deemed 
the disposal of high-level nuclear waste 
"trivial".  He failed to state what the solution 
would be, and I have always remembered his remark 
as one of the wildest I've ever heard.
	Some truly wonky 'solutions' have been 
proposed by respectable experts.  For instance, 
the USA govt for a period envisaged, among other 
options, placing metal canisters of high-level 
waste on the Antarctic ice-cap; the radiodecay 
heat would cause them to melt their way down, out 
of sight out of mind.  It was already known then 
(and has been amply confirmed since) that liquid 
water lies under some parts of that ice-cap, the 
connection of which to the ocean was unclear but 
certainly couldn't be ruled out for the timescale 
in question.
	Another gasser was touted by Harwell 
refugee James F. Duncan, a politically 
influential chemistry prof at my alma mater: 
rocket them into the sun.  It is surprisingly 
difficult to send anything from our planet into 
the Sun, rather than creating a very eccentric 
orbit for a cargo which might later return to 
Earth; and anyhow the failure rate of big rockets 
before they leave the atmosphere would rule out 
this stupid idea.
	Nevertheless, I have believed for a 
couple decades that high-level waste could be 
reasonably disposed of in deep geological 
formations.  I suspect the fabled 'powers that 
be' have been (except perhaps in the USSR) 
refraining from doing so because they like to 
keep this issue on the boil for Greepneace etc to 
focus on, drawing attention away from more 
difficult unsolved problems of fission power.

RM


<http://www.nature.com/news/2010/100810/full/466804a.html>http://www.nature.com/news/2010/100810/full/466804a.html

Published online 10 August 2010 | Nature 466, 
804-805 (2010) | doi:10.1038/466804a 
<http://www.nature.com/news/2010/100810/full/466804a.html#update1>Updated online: 13 
August 2010


France digs deep for nuclear waste

Geological storage of long-lived radioactive 
material is moving closer to reality in Europe, 
says Declan Butler.

<http://www.nature.com/news/author/Declan+Butler/index.html>Declan Butler

  The tunnels of the Bure laboratory are still 
being carved out of the 150 million-year-old 
rock.B. Tinoco/ANDRA

"It'll be about 8 minutes before we reach the 
490-metre lab level," shouts an official, barely 
audible above the roar of machinery, as we slam 
shut the heavy doors of the small lift and 
trundle slowly towards the depths of the Earth.

Here, half a kilometre beneath rolling wheat 
fields outside the small town of Bure in 
northeast France, the country is preparing to 
dispose of its radioactive waste.  In a 
¤1-billion (US$1.3 billion) underground 
laboratory, 
the <http://www.andra.fr/international/index.html>French 
National Radioactive Waste Management 
Agency (ANDRA) is testing the soundness of the 
rock and the technologies to contain the waste. 
ANDRA scientists are convinced that the rock 
formations can safely house highly radioactive 
waste, and plan an industrial-scale facility that 
would open deep below a 30-square-kilometre site 
nearby in 2025.  It would be among the world's 
first geological repositories for high- and 
medium-level long-lived nuclear waste - and the 
largest.

The warren of tunnels under Bure is at the 
vanguard of several parallel efforts across 
Europe to come up with a permanent home for the 
long-lived waste that is accumulating at 
temporary storage sites.  Projects that started 
decades ago are finally coming to fruition. 
Finland and Sweden plan to open deep geological 
repositories in about 2020-2025, whereas Germany 
hopes to open its own long-term repository in 
2035.  Several smaller European countries have 
banded together to form 
a <http://www.erdo-wg.eu/ERDO-WG_website/Home.html>European 
Repository Development Organisation to work on 
the concept of a shared facility.

By contrast, development of the United States' 
only proposed long-term repository, at Nevada's 
Yucca Mountain site, has stalled again and looks 
set to be abandoned after two decades of work and 
more than $10 billion in investment 
(see <http://www.nature.com/uidfinder/10.1038/4581086a>Nature 458, 1086-1087; 
2009).  The Obama administration wants to scrap 
the Yucca Mountain site, and has created a 
commission to explore alternatives. One of the 
main problems is that the selection of Yucca 
Mountain by the US Congress in 1987 was, from the 
outset, a political rather than a scientific 
choice. "There are far better geological sites in 
the US than Yucca Mountain," says Patrick 
Landais, a geologist and scientific director of 
ANDRA, as we tour the lab in hard hats and 
fluorescent overalls.  Like many experts, he 
questions Yucca's geological suitability: "When I 
went to the top of Yucca Mountain and saw the 
volcanoes below, that worried me."

Efforts by the US federal government to find a 
site have been stymied by opposition from 
individual states, where people are uneasy about 
having a nuclear dump in their backyard. European 
countries have taken a more scientific and 
stepwise approach to locating sites, which has 
engendered greater public confidence - in typical 
Scandinavian tradition, Sweden and Finland 
involved local communities in decisions from the 
outset, which has increased acceptability.

  Sensors in the tunnel walls monitor the rock around the clock.E. Sutre/ANDRA

France generates about 80% of its electricity 
from its 58 nuclear power plants, and is a world 
leader in the technology.  Nuclear power enjoys 
staunch cross-party support in the country, and 
the economic incentives that the storage facility 
offers to the Bure region have been welcomed by 
local officials. Anti-nuclear groups also have 
little clout.  Perhaps unsurprisingly, there has 
been little effective resistance to the Bure 
facility. Mobilizing public opinion to oppose the 
repository is difficult because the majority of 
the French are "indifferent" to nuclear power 
issues, says Sophia Majnoni, head of Greenpeace 
France's nuclear campaign.  The group does not 
oppose geological storage research, but is 
concerned that plans to seal the repository after 
a century of use would make it almost impossible 
to deal with a subsequent problem in the facility.

The Bure lab, created in 1999, has largely 
established the geological suitability of the 
area, with its findings endorsed by international 
experts.  Now, it is shifting into high gear, 
spending ¤100 million a year on research to pin 
down exactly how waste would be stored at the 
planned repository.  ANDRA must present a 
blueprint for the repository to the government in 
2014; if approved by the French National Assembly 
in 2016, construction would begin the following 
year. The assembly will then consider licensing 
the facility to open in 2025.

Once completed, the repository would store all of 
the existing 2,300 cubic metres of high-level and 
42,000 cubic metres of medium-level long-lived 
radioactive waste - most of which has been 
generated by France's nuclear power stations - as 
well as new waste created over at least the next 
20 years. The existing waste is currently being 
stored at temporary sites in La Hague, Marcoule 
and Cadarache.

Test lab

The lab itself contains no radioactive waste, and 
never will. Instead, researchers at Bure are 
focusing on testing the rock and prototype 
waste-containment strategies. Almost all of the 
research results are analysed remotely. Once 
scientists have installed their experiments, the 
output of instruments lining the tunnels is 
transmitted via the Internet to ANDRA's own 
researchers, along with 80 collaborating labs at 
other research agencies and universities in 
France and other European countries involved in 
the project. Jacques Delay, the geologist in 
charge of coordination and experimental 
strategies at the lab, shows me the screens of 
the remote data-access system: a 
three-dimensional representation of the galleries 
in which one can zoom in on any tunnel to find an 
experiment, and pull up its data output and 
graphs in real time.

"The idea of a geological safe does not exist."


But dozens of scientists and engineers must still 
make the long descent every day, and working at 
such depths is not without risk.  Before we board 
the lift, I get a crash course in using the 
chunky 'self-contained self-rescuer' device 
strapped around my waist.  It is a closed-circuit 
breathing apparatus used in the mining industry, 
which can provide 20 minutes of chemically 
generated oxygen should a power outage cut the 
tunnels' ventilation.

The lift slows at a depth of 445 metres, then 
creeps to the bottom. A few minutes later, we 
push open the doors into galleries crammed with 
scientific instruments. Incessant tannoys, and 
the din of pneumatic drills and earth borers at 
work extending the lab, fill the air.  The tunnel 
walls are reinforced with concrete, steel ribs 
and bolts, but here and there the grey 
150-million-year-old Callovo-Oxfordian 
argillaceous rock that would seal the repository 
is left bare.

On the pulse

Fine experimental boreholes in the walls carry 
about 3,500 sensors, which take the pulse of 
almost every mechanical, chemical and 
hydrogeological aspect of the rock. The data are 
fed into models that characterize the rock and 
also predict its future behaviour over periods 
from decades to more than a million years. "No 
other rock lab in the world is as highly equipped 
as this one," Landais says.

The experiments ultimately aim to answer one key 
question: can France's most dangerous radioactive 
wastes be safely contained inside this 
150-metre-thick layer of rock? The high-level 
waste includes the radioactive fission products 
caesium-134, caesium-137 and strontium-90, and 
minor actinides such as curium-244 and 
americium-241. Most nuclear fuel in France is 
reprocessed to extract useful uranium and 
plutonium, and to concentrate the waste. Although 
this high-level material comprises just 0.2% of 
France's nuclear waste by volume, it accounts for 
95% of its total radio°Šactivity.

  Robots will store high-level waste in boreholes.

The waste is immobilized by blending it into 
glass, in a complex vitrification process 
pioneered by the French. The molten glass is 
poured into stainless steel casks, which are then 
placed inside steel barrels. Robots in the Bure 
repository will push these barrels into 
70-centimetre-diameter boreholes called alveoli, 
drilled 40 metres horizontally into the walls of 
the main access tunnels.

The medium-level radioactive waste, meanwhile, 
which comes from used reactor equipment and 
reagents, would be compressed into circular cakes 
and piled into steel canisters, before being 
encased in concrete and stored in the tunnels.

Scientists at Bure are already testing the 
stability of the glass that would be used to 
immobilize the high-level waste, the rates of 
corrosion of the stainless steel casks, and the 
fate of the hydrogen gas that this degradation 
releases. They are also assessing all the 
interactions between the glass, the layers of 
steel and the rock in prototype alveoli.

The canisters are designed so that heat from 
radioactive decay inside does not warm their 
surface beyond 90 °C. Tests using mock-up 
canisters have shown that prolonged exposure to 
this temperature does not cause the rock to 
fissure. Although the volume of high-level waste 
is much smaller than that of medium-level waste, 
it will require double the amount of storage 
space, because the hot casks must be spaced out 
with empty ones to avoid overheating. The 
scientists are also investigating ways to reduce 
the volume of waste to be sent to the facility. 
"Geological storage is a rare and precious 
resource," says Landais. Extracting radioactive 
elements from bulky graphite fuel elements and 
then concentrating them, for example, could allow 
much more medium-level waste to be packed into 
the repository's chambers.

The repository could eventually operate for at 
least a century, after which it would be sealed. 
A few thousand years later, the stainless steel 
would corrode away until it was ruptured by the 
pressure of the rock, leaving the vitrified 
waste, and the rock itself, to provide 
containment.

Rock is not an absolute barrier, says Landais. 
"The idea of a geological safe does not exist." 
Radionuclides would slowly diffuse through it. Of 
most concern at Bure are radioactive iodide and 
chloride anions, which are the most mobile in 
this type of rock. But Landais says that it would 
take hundreds of thousands of years for them to 
diffuse to the surface. By that time, he says, 
their low concentrations and lower levels of 
radioactivity would render any environmental 
contamination negligible.

A more worrying problem is the possibility of a 
rock fracture, which could lead to radioactive 
leaks. But the research at Bure has largely 
confirmed that the layer of rock that would house 
the repository is homogenous, highly impermeable 
to water movement and free from faults and 
seismic risk.

At the surface, researchers are extensively 
sampling the air, water and soils in a 
250-square-kilometre zone around the site to get 
a comprehensive baseline of environmental data. 
An observatory, created jointly in April with 
France's agricultural research agency, INRA, will 
monitor this ecosystem for at least a century.

The geologists at Bure are confident that it is a 
safe place for nuclear waste.  The rock is 150 
million years old, hasn't budged in the past 20 
million years, and won't in the next, they say. 
With the lab's panoply of sensors, measurements 
and models "we might make a mistake of a few per 
cent, but nothing major", says Landais.  "The 
geology is predictable."

UPDATED:

Clarification: The area of the repository site - 
30km^2^ - refers to its size on the surface; the 
underground repository itself will be smaller.