Abstract
The Finnish company Posiva Oy is constructing a
repository for the final disposal of spent fuel in the
bedrock of Olkiluoto, an island in the Gulf of Bothnia.
The disposal is based on geological barriers and
engineered barrier systems (EBS) that isolate the nuclear
waste form the biosphere and maintain the protective
function of the repository. Monitoring during
implementation of the repository is used to provide
information on the performance of the barriers and to
strengthen confidence in long-term safety, which is the
key objective of radioactive waste disposal.
Posiva Oy has established a general monitoring program
that ensures the applicability of the constructed
facilities to the final disposal of nuclear spent fuel. A
program defining the methods and systems that will be
chosen to monitor and instrument the engineered barrier
systems is currently under preparation. It gains
substantial knowledge and monitoring experience from
experiments and demonstrations in Posiva's underground
research laboratories.
The full-scale underground experiment POPLU is one of the
demonstrations in a project of Euratom's Seventh
Framework Programme called DOPAS ("Full-Scale
Demonstration Of Plugs And Seals"), which is running from
2012-2016. The DOPAS project will compile the design
basis of plugs and seals, develop new technology for plug
and seal materials and for the assembly and construction
of plug and seal systems, carry out full or partial
design of the systems, and perform partly or wholly five
full-scale plug and seal tests
(http://www.posiva.fi/dopas). Within POPLU a deposition
tunnel end plug for deep geological repositories is being
constructed at Posiva's underground rock characterization
facility ONKALO in the crystalline bedrock of Olkiluoto.
It separates the demonstration tunnel from the vehicle
connection and is instrumented with sensors continuously
measuring displacements, strain, humidity, mechanical and
pore water pressure and temperature under very demanding
conditions. Furthermore, wired and wireless sensors allow
for monitoring the pressure being applied by pumping
water into a filter layer behind the plug and the
observation and control of the main parameters needed
during the pressurization of the structure. An artificial
pressurization routine is conducted within the short
timescale of the demonstration in order to simulate the
100 year expected lifetime of the concrete structure. The
in-pumped water and any out-flowing leakage will also be
determined by a monitoring system to analyse the
performance of sealing mechanisms of the structure.
The project monitoring and instrumentation plan builds
upon the experiences gained in other ONKALO
demonstrations and profits by the knowledge transfer from
related disciplines with a strong background in Finland,
like infrastructure monitoring, sensor development,
wireless systems networks and ICT.
Original language | English |
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Number of pages | 26 |
Publication status | Published - 2014 |
Event | GeoRepNet 2/RATE meeting: Linking science and technology in Geological Repositories - Nottingham, United Kingdom Duration: 23 Oct 2014 → 24 Oct 2014 |
Conference
Conference | GeoRepNet 2/RATE meeting |
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Country/Territory | United Kingdom |
City | Nottingham |
Period | 23/10/14 → 24/10/14 |
Keywords
- nuclear waste management
- monitoring
- plug
- repository