Mock-up OPHELIE - Dismantling

concretecakeΠολεοδομικά Έργα

29 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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Mock
-
up OPHELIE
-

Dismantling


Jan Verstricht


Exchange meeting n
°

2


31 May 2001


Outline


Current status of the mock
-
up experiment


Preparation of the dismantling


Dismantling objectives


Post
-
dismantling investigations


Scenario and implementation


Conclusion

Current status of the mock
-
up


Overview of the set
-
up


Hydration and heating history


Main measurement results


temperature evolution


pressure evolution


Other observations


chemical phenomena

Experimental set
-
up: mechanical details

welded cover

main cover

4785 mm

55 mm thick + 3 mm lining

Ø 458 mm

25 mm thick

Ø 2000 mm

disposal tube with heating
elements

flexible joint

feed
-
through (2x) for

instrumentation
cables

hydration tube

(x 16)

Instrumentation of the mock
-
up

Concrete segment ring and

temperature control system

heating cables

load cells

pressure cell

Different phases of the mock
-
up


hydration at ambient temperature


heating (with external temperature control)


cooling


dismantling and analyses

1997
1998
1999
2000
2001
2002
1Q
2Q
3Q
4Q
1Q
2Q
3Q
4Q
1Q
2Q
3Q
4Q
1Q
2Q
3Q
4Q
1Q
2Q
3Q
4Q
1Q
2Q
3Q
4Q
mounting of set-up
start heating, 2 Jun
flooding, 2 Dec
dismantling and analyses
end of heating
Evolution of hydration (volume injected)

Temperature evolution

Backfill pressure sensors (Kulite)

Overview of observations


Higher than expected (apparent) thermal
conductivity


Low swelling pressures


Pitting corrosion detected on stainless steel tubing


Sensor failure


Water samples show high content of Cl
-


most probably from the backfill itself


Presence of free sulphides in the mock
-
up water

Evidence of geochemical phenomena


Mass transport process within the backfill material


advective transport of soluble salts by a water front


migration through an unsaturated material


advection/evaporation cycles (heat pipes)


thermo
-
osmosis, thermo
-
diffusion


Presence of free sulphides


residual pyrite


sulphate reducing mechanism (thermal or microbial)

Preparation of the dismantling


working group
(EURIDICE, SCK•CEN, N/O):


definition of objectives


overview of analyses and investigations


sampling programme


dismantling scenario


technical and logistical support


dismantling and sampling techniques


quality assurance


safety


input from DAC (May 10), SAC with Int’l experts
(25 June)

Dismantling objectives and
applications


better understanding of the backfill behaviour


main phenomena (THM, physico
-
chemical, microbiological) occurring in
backfill during the experiment


consequences on integrity and performance of the mock
-
up components


performance of metallic components (corrosion susceptibility) and concrete
segments in HLW disposal conditions


scientific and technical optimisation of the PRACLAY in
situ experiment


components, installation


monitoring (what to monitor, which sensors)


input for current review of HLW disposal concept

Analyses and investigations (1/3)


hydration process: saturation degree?


density and water content distribution


permeability tests


thermal characteristics


conductivity


other heat transfer mechanisms (mass transport)


occurrence of corrosion


analysis of main metallic components in contact with backfill


incl. physico
-
chemical and microbiological characterisation


porewater chemistry (squeezing or leaching)


microbiological analyses (Sulphato
-
Reducing Bacteria)

Analyses and investigations (2/3)


HM properties of backfill material


swelling, retention curve


performance of central tube


rechecking tube dimensions (plastic deformation)


quality of welding (related to corrosion)


sensor performance


recalibration to correct measurement data


failure mode where applicable

Analyses and investigations (3/3)

Additional opportunities of dismantling


Behaviour of joints between backfill blocks


physico
-
chemical and hydraulic behaviour


Geomechanical properties of backfill


E,
n
, Mohr
-
Coulomb


Concrete characterisation


mechanical behaviour


compression and tension, flexion, shear strength


ultrasonic auscultation


porosity, water content, water infiltration depth


Concrete
-

backfill (clay) interface (“alcaline plume”)

Location of the backfill samples

29
28
27
26
18
10
9
7
4
3
2
1
8
36
35
34
33
32
31
30
25
24
23
22
21
20
19
17
16
15
14
13
12
11
6
5
Zone A
Zone B
Zone C
Zone D
Temperature profile

Water content and density distribution

Sampled sections
Sample location
30
29
28
27
26
25
24
23
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
22
8
36
35
34
33
32
31
SECTION 31, 25, 17, 9 and 3
SECTION 36 and 33
Sect. 17
Sect. 17
General remarks


sampling operations


no sampling at elevated temperature/pressure


backfill characterisation after heated phase (

at elevated temperature)


sampling has to be representative for the mock
-
up state


porewater chemistry:best practices (leaching, squeezing)


backfill characterisation


understanding of main processes


requires knowledge of boundary conditions (Eh, pH,…), even if these are
not representative for in situ conditions


is backfill able to fulfil its requirements?


Dismantling Scenario


phase 1: final preparation before heater switching off


final check of all equipment and work procedures


water sampling for geochemical characterisation


porewater composition


dissolved gas (may indicate chemical or microbiological processes)


Eh
-
pH measurements


sensor status check

Dismantling Scenario


phase 2: cooling phase


central tube: general position (survey), internal dimensions


rapid cooling to preserve state (2 to 4 weeks)


complete switch
-
off, with removal of thermal isolation


external water pressure cut
-
off when T
max

< 100
°
C


rapid pressure drop


penetration test through one of the instrumentation covers


when mock
-
up is not more than 5
°
C warmer than demohall


radial profile sampling of backfill


drilling through jacket


pressure


water sampling

Dismantling Scenario


phase 3: instrumentation


sensor status, re
-
organising of data
-
acquisition


selected sensors will be read
-
out during dismantling


purging hydration circuit


removal instrumentation covers

Dismantling Scenario


phase 4: removal of main cover and
sampling/removal of backfill



dismantling / sampling operations


conditions: 24h/24h, 7/7 days


retrieval of central tube


sampling of metallic components


cleaning operations

Dismantling/sampling operations

Method (1/2)


Continuous visual inspection of backfill, sensors
and metallic structure during dismantling


special features, e.g.

anomalous consistency/colour






cavities (water filled)






joints between blocks






corrosion


additional samples may be taken



optical survey to record systematically the location
of all samples and sensors

Dismantling/sampling operations

Method (2/2)


Documentation


video shots of all main operations


dismantling logbook


sampling sections


sample track records


Dismantling crew of seven persons


sampling/dismantling: 2 + 1


sample packaging (labelling, storage): 2 + 1


general co
-
ordination: 1


All equipment, work procedures, and operations under
supervision of safety manager

Logistic support


removal and sampling of backfill material


behaviour of backfill material?


homogeneity


Quality Assurance (procedures, forms,…):
traceability


recording of all dismantling/sampling and pre
-
/post
-
dismantling
operations


sample track record for each sample (backfill core, sensor,…)


operations according to procedures/instructions


flexibility for non
-
conformities, with registration




QA to reduce risk of errors, which could lead to loss of data,
wrong interpretation of results

Global planning of the dismantling

2001
2002
2003
1Q
2Q
3Q
4Q
1Q
2Q
3Q
4Q
1Q
2Q
3Q
4Q
cooling
dismantling - sampling
post-dismantling analyses
final report of mock-up experiment
Conclusion and perspectives


Dismantling objectives


defined by large participant base


Specification of analyses and tests


Detailed work plan


minimal time span for dismantling activities


quality assurance for maximum reliability of results


Final review of all measurement data, observations,
and analysis and test results with our main partners




final conclusion of mock
-
up experiment