The Onkalo nuclear waste repository is being constructed in Finland to store highly radioactive nuclear waste for 100,000 years. It involves excavating a network of tunnels 400-450 meters underground in solid granite bedrock. Once operational in 2020, nuclear waste will be sealed inside copper capsules and buried in the tunnels. However, some scientists have criticized the project, arguing that the copper capsules may corrode more quickly than expected, in only around 1,000 years rather than the intended 100,000 years. Constant water leakage into the tunnels also poses a challenge to the long-term safety and isolation of the nuclear waste.

1. Radioactive material is highly toxic to unimaginable
timescales.
But in Finland, they’d proposed with the world's first
permanent nuclear-waste repository -- "Onkalo" -- a huge
system of underground tunnels, being hewn out of solid
rock andTHAT must last at least
100,000 years.
GREATEST QUESTION OF OUR AGE:
WHAT TO DO WITH NUCLEAR WASTE?

2. INTO
INFINITY
ONKALO SPENT NUCLEAR FUEL REPOSITORY
FINLAND
…….on track to be the first “official” repository in the world to
quarantine high-level nuclear waste for a long time……

4. INTRODUCTION
• It is currently under construction at the Olkiluoto Nuclear Power Plant in the
municipality of Eurajoki, on the west coast of Finland, by the
company Posiva.
• The estimated cost of this project is about €818 million, which includes
construction, encapsulation, and operating costs.
• The Onkalo repository is expected to be large enough to accept canisters of
spent fuel for around one hundred years, i.e. until around 2120.
• Onkalo is being designed to last 100,000 years.
• Deep geological repository for the final
disposal of spent nuclear fuel, the first
such repository in the world

5. • Onkalo will be ready to take waste in
2020, and then will be finally sealed in
2120, after which it will not be opened
for 100,000 years.
• Why 100,000 years???
• Because, by 100,000 years the spent
nuclear waste will loose its harmful
radioactivity.

6. HISTORY • After the Finnish Nuclear Energy
Act was amended in 1994 to specify
that all nuclear waste produced in
Finland must be disposed of in Finland,
Olkiluoto was selected in 2000 as the
site for a (very) long-term underground
storage facility for Finland's spent
nuclear fuel.
• The facility, named "Onkalo" (meaning
"cave" or "cavity") is being built in
the granite bedrock at the Olkiluoto
site, about five km from the power
plants.
• The municipality of Eurajoki issued a
building permit for the facility in August
2003 and excavation began in 2004.

7. The
Surrounding
Bedrock
• The main rock type in Olkiluoto bedrock
is gneiss.
• The bedrock in the area is
approximately 1,800 to 1,900 million
years old.
• There are various types of structures in
the rock, some of them water
conductive.
Spent nuclear fuel will be
disposed of in a depth of about
400-450 meters inside Olkiluoto
bedrock. Deep inside the
bedrock, the prevailing
conditions are stable and
predictable.

8. Continue… • Olkiluoto bedrock has been studied ever
since the 1980s.
• There have been a number of studies,
some of which are still underway, using
such methods as aboveground drilling
and investigation trenches, as well as
constructing the underground rock
characterisation facility,ONKALO.
An approximately 2 billion year old
gneiss sample from the Onkalo deep
geologic repository

9. Site
Investigation
• Site investigations related to final
disposal of spent nuclear fuel have
been carried out in Olkiluoto ever
since the 1980s.
• One of the major site investigation
methods is to drill deep drillholes and to
use them in various groundwater
investigations.
• Other important methods are
excavating investigation trenches and
conducting variable geophysical
examinations.

10. Drilling • The bedrock in Olkiluoto is
investigated by drilling holes of up to
one kilometre deep, from ground
surface. By 2014, a total of about 60
holes have been drilled.
• Drilling produces a drill core sample of
some five centimetres in diameter.
• It is carefully studied to establish the
degree of fracturing and types of rock
present in the bedrock.
• The in-hole measurements and samples
taken from the drill hole allow studying
of the flow and qualities of
groundwater.
• Geophysical measurements and
imaging also take place in the holes.
Drill core samples reveal the
structures and rock types of the
bedrock

11. Geophysical
investigations
• Geophysics can be used to
examine rock structures which
are hidden to naked eye.
• Geophysics makes use of the
physical properties of the Earth,
such as
– magnetism
– electrical conductivity
– density
– elasticity
– radioactivity.
Geophysical investigations in
the summer of 2013 in
ONKALO.

12. Seismic
investigations
• Downhole logging methods applied in
deep drill holes.
– These include imaging surveys (acoustic and
optical), and methods describing directly
physical properties of rock mass, like
magnetization, density, conductivity, and
velocity.
• Acoustic logging is carried out in all
deep drill holes and pilot holes of
ONKALO.They reveal the elastic
properties of rock in immediate vicinity
of measurement holes.
Seismic measurements have
been carried out in Olkiluoto
in conjunction with site
investigations since the
beginning of the 1990s.

13. Research
Conducted in
ONKALO
• Helps to ensure the suitability of the
Olkiluoto bedrock for the final disposal.
• Helps to identify the areas where the
construction of the final disposal
tunnels is the most cost-effective.
• Geological mapping is the method for
collecting information related to the
tunnel walls.
• Information about the rock to be
excavated is obtained by drilling probe
and pilot holes.
• From the tunnel, it is also possible to
perform exploratory drillings and to
study the groundwater flowing into the
tunnel.

14. Geological
Mapping of
ONKALO
• The geological mapping of ONKALO is
divided into two parts:
– mapping performed in the constructed
tunnel immediately after excavation
– a more precise systematic mapping.
• The first phase mapping proceeds
simultaneously with excavation work so
that the mapped area is located at 10 to
15 metres from the rear end of the
tunnel.
• Geologists determine the main rock
type in the area and collect versatile
information on the fracturing and
quality of the rock.

15. Probe and
Pilot Holes
• From the rear end of the ONKALO
tunnel, a number of pilot holes have
been drilled at pre-determined
locations.These pilot holes will remain
within the tunnel profile.
• The purpose of these pilot holes is
– to verify the rock quality at the location the
tunnel
– to locate any water-conducting fracture
zones
– other rock characteristics that may be
significant for the construction.

16. Electrical
charged
potential
measurements
• The electrical charged potential
method, a well established method in
ore exploration, has proven to be an
excellent tool for verifying the
geological connections in Olkiluoto.
• The method involves measuring the
flow of electricity through the rock. An
electrical connection is often an
indication of a hydraulic connection,
and this knowledge is useful in
predicting groundwater movements.

17. Ground
water
studies in
Onkalo
• The volume of water leaking into tunnel
is measured and characteristics of
groundwater are studied.
• Measurement of volume of leaked
water is recorded by measuring weirs
installed in tunnel.
• A visual leak water analysis is
performed for ONKALO roof and walls
twice a year to find leak spots and
detect possible changes.
• Composition of groundwater is also
examined by groundwater stations and
monitoring holes.

18. CONSTRUCTION
PHASES
• The facility is being
constructed by and will be
operated by Posiva, a
company owned by the two
existing producers of nuclear
power in
Finland; Fortum andTVO.
• ONKALO consists of one
access tunnel and three
shafts: a personnel shaft and
two ventilation shafts.The
slope of the tunnel is 1:10. It is
5.5 m wide and 6.3 m high.

19. CONTINUE…
• The facility's constructions plans are divided into four phases:
– Phase 1 (2004–09) focused on excavation of the large access tunnel to the
facility, spiralling downward to a depth of 420 metres (1,380 ft).
– Phase 2 (2009–11) continued the excavation to a final depth of 520 metres
(1,710 ft).The characteristics of the bedrock were studied in order to adapt
the layout of the repository.
– Phase 3, the construction of the repository, is expected to begin around
2015.
– Phase 4, the encapsulation and burial of areas filled with spent fuel, is
projected to begin around 2020

20. CONTINUE…
• Once in operation, the disposal process would involve putting twelve
fuel assemblies into a boron steel canister and enclosing it into a copper
capsule. Each capsule would then be placed in its own hole in the
repository and packed with bentonite clay.

21. The ONKALO area in August
2004.The first blast of the
construction had been
implemented a few months
before...
...and this is how the area
looked in summer 2014, ten
years later.

22. Construction
method
• The access tunnel is excavated by drilling
and blasting:
– at the beginning of excavation, a number of
holes are drilled and then filled with
explosives.
• Once the rock material has been blasted,
the rock waste is moved away.The rock
walls are then washed and any broken
stones are dropped down.
• The rock is sealed, where necessary, by
grouting before and after excavation.
• Cemented anchor bolts made of ribbed
steel bars as well as shotcrete are used to
strengthen the rock.
The method used for
excavating ONKALO
is drilling and
blasting.The shafts
are constructed by
raise boring.

23. Shafts
Constructed
by Raise
Boring
• There will be three shafts in ONKALO: a
personnel shaft, a supply air shaft and an
exhaust air shaft.
• The diameter of the passenger shaft is 4.5
m and the diameters of the supply air
shaft and exhaust air shaft are 3.5 m.
• The shafts are constructed with the raise
boring method.
• The reamer bit moves upward at about
half a meter per hour.
• Approximately 100 m of shaft is drilled at
one time.

24. Threat to
ONKALO
Project
• Constant water leakage into the tunnel
from the surrounding bed rock is of high
concern.
• The droplets are leaking into the tunnel
from tiny fractures in the rock, smaller
than a millimeter, at a rate of about 20
liters per minute. In tunnel terms, that’s
slow, and that’s good news.
• At each new depth, geologists extract slim
rock cores in search of telltale
”structures”—the fractures and crevices
that determine how water moves in rock.
• So far, Onkalo appears to have
uncharacteristically few structures, which
explains why the tunnel is only damp and
muddy rather than flooded with a torrent
of water escaping from its high-pressure
home in the rock.

25. The
Criticism
• Research argues that corrosion in pure
copper advances at about
one micrometre a year, whereas KBS-3
depends on a rate that’s a thousand
times slower.
• STUK (Finnish nuclear safety office) has
asked Posiva for further explanation,
and independent research conducted in
Finland has supported the results of
Szakálos's group.
• Posiva dismissed it all in public. Later
studies by SKB determined corrosion
process does not exist & initial
experiments were not correctly
executed and/or wrong conclusions
were drawn.
• 2012: A research group at Royal
Institute ofTechnology (Stockholm,
Sweden) published research
suggesting that copper capsules of
KBS-3 are not as corrosion-proof as
Posiva claims.
• Research group led by Peter Szakálos
found that copper capsules would
last only about 1,000 years, instead of
100,000 years claimed by companies.

26. Into Eternity is a
feature documentary
film directed by Danish director
Michael Madsen, released in
2010.It follows the construction
of the Onkalo waste
repository at the Olkiluoto
Nuclear Power Plant on the
island of Olkiluoto, Finland.
Director questions Onkalo's
intended eternal existence,
addressing an audience in the
remote future.
Into Eternity raises the question
of the authorities' responsibility
of ensuring compliance with
relatively new safety criteria
legislation and the principles at
the core of nuclear waste
management