SAMPOsafir2022.vtt.fi/interim2021/day2/4_SAFIR2022 Mechanical... · 2021. 4. 12. · SAMPO WP1 -...
Transcript of SAMPOsafir2022.vtt.fi/interim2021/day2/4_SAFIR2022 Mechanical... · 2021. 4. 12. · SAMPO WP1 -...
SAMPO Safety criteria and improved ageing management
research for polymer components exposed to thermal-
radiative environments
SAFIR2022-KYT2022 Interim Seminar
18-19.3.2021
SAMPO
WP1 - Acceptance criterion
and safety margin
assessment
T1.1 – Improved estimation
for lifetimes of critical
polymer components
T1.2 – Sensitivity of
polymer properties to
additive content and
methods to verify polymer
quality
T1.3 – Setting up safety
margins for O-rings
WP2 - Improvements in
ageing management of
polymer components
T2.1 – Online condition
monitoring techniques
T2.2 – Sensitive analysing
techniques
T2.3 – Improved
interpretation of non-
destructive testing data
WP3 - International
cooperation
T3.1 – Polymer ageing in NPP
applications – event
organization
WP1 – T1.1. Improved estimation for lifetimes of critical polymer components
• Aim: Compare artificial accelerated
ageing to real ageing of components
used in NPP in order to:
– Improve knowledge about
material status after use in
NPP i.e. in true service
environment.
– Estimate residual service life of
polymer components.
– Find relevant exchange
intervals.
• Progress and work during 2019-
2020
– Workshops at Ringhals,
Forsmark and TVO for
product/material selection and
supply for laboratory
investigations.
– Oven ageing and laboratory
tests (hardness tests and
tensile testing) of selected
materials.
• Challenges and future work: Find
materials with known service history.
MembraneReinforced seal from TVO
Tensile
strength
(MPa)
Tensile
elongation
(%)
Hardness
(IRHD)
Naturally aged 6,92 294,5 72,4
Naturally aged
+ heat ageing
7,01 283,1 78,3
The table above shows TVO (Olkiluoto) seal aged in air at 120°C for 45
days and mechanically tested (tensile and hardness test). The ageing
time simulates approximately 20 years at 45°C.
Ringhals membranes have not been tested mechanically (tensile and
hardness test). Not aged due large spread in test results and uncertainty
of service environment during use.
WP1 – T1.2. Sensitivity of polymer properties to additive content and methods to verify polymer quality (VTT)
▪ Develop methods that can be used on-site for quality
management of polymeric components
▪ Literature survey to list various analysis methods and
identify applicable analysis methods for on-site
• OIT and FTIR for antioxidants
• TGA+EDS for filler analysis
▪ Show the capability of the methods to be used as part of
quality management
• Initial proof on their resolution have been provided
→ OIT clearly changes as PE is aged
→ TGA+EDS to measure carbon black filler in EPDM
rubber
▪ Future work: show the detection limits of the techniques
and provide on-site measurement procedures
9.4.2021 VTT – beyond the obvious 4
OIT unaged PE180 min
OIT aged PE10 min
TGA of EPDM:• 40,0% filler content• Additional EDS analysis
to exclude other non-volatile additives
→ 37,8% filler content• Combining EDS to TGA
improves the accuracyof the filler analysis
Smaller sample Larger sample
Element W% A% W% A%
C 94.39 98.71 94.56 98.76
S 1.06 0.42 0.97 0.38
Zn 4.55 0.87 4.47 0.86
WP1 – T1.3 Setting up safety margins for O-rings
• O-rings are mounted in valves, pipes etc. to prevent
leakage. Upon use in under compression the rings
finally start to leak.
• Compression set properties are measured according to
standard test methods to decide end of life values for o-
rings. Leak tests are performed to better correlate end
of life values to leakage in order to improve them.
• Rig design is updated (see left picture) - Indentation
created / slot for O-ring to sit, thus more realistic to
operating conditions.
• Water leak test rigs have been tested (right picture) to
verify the test method and the re-designed test rig.
Compression set on standard samples of standard
quality EPDM was performed and compared to high
quality NPP grade EPDM.
• The old test rig showed leakage after 30 days and 60
days at 140°C, meaning that the new rig keeps the o-
rings in place resulting in sealed rigs and no leakage.
• Work during 2021: Calculate activation energies for
tested materials and simulate LOCA conditions on test
materials. RISE — Research Institutes of Sweden5
Leak test setup
Leakage was observed only for the old rig, 140
WP2 - T2.1 Online condition monitoring techniques
Fig: Main trend in change appears similar for two measurement types
performed
RISE — Research Institutes of Sweden6
Aim:
To find possible methods to monitor and detect aging of polymers in situ.
Main results:
Based on literature studies in this should be possible through detection of changes in
electromagnetic (EM) material properties (i.e. permittivity).
Borrowed equipment was used for broadband (~105 -1010 Hz) characterization of
samples.
Measurements performed on new materials and materials previously aged at different
conditions. The measurements indicate changes.
Online monitoring of samples during (slow) ageing at moderate temperature, short time
span (40 days) and low temperature (50°C). Longer time period would be preferred.
Challenges and future work include:
• High sensitivity to noise. To find equipment to use for a longer time period.
• Finding samples suitable for developing this technology including simple rubber
formulations and shape, flat surface for probe face.
WP2 - T2.2 Sensitive analysing techniques
• Accelerated ageing for life time prediction is
often performed at elevated temperature to
decrease ageing times. At high temperatures
degradation mechanisms are known to be
different to those at ambient temperature.
• Therefore the goal is to develop a sensitive
analysis methods, known as Microcalorimetry to
measure the chemical changes closer to the real
operating conditions for polymeric materials
used in NPP.
• Microcalorimetry measures evolved heat from a
sample in the test chamber.
• In the project EPDM, Nitrile, PS, FT6230 (food
grade polymer), James Walker rubber material
(standard and top quality) samples were
analysed at different temperatures.
SEM image after EPDM was aged in
IMC 45-90 °C, using 100 μm
magnification. Antioxidants have
migrated to the sample surface.
RISE — Research Institutes of Sweden7
SEM image for fresh EPDM using
100 μm magnification
Normalised heat flow (μW/g) for EPDM non-aged
and EPDM already aged at 120 °C. The IMC test
was conducted at six different temperatures 45 °C,
50 °C, 60 °C, 70 °C, 80 °C and 90 °C for two
weeks. Temperature steps are shown by a dotted
line.
WP2 - T2.3. Improved interpretation of non-destructive testing data (VTT)
▪ Modulus (E) and crystallinity degree (CD) were identified as non-
destructively measurable ageing parameters that can be predicted by MD
simulations
▪ E can be measured non-destructively by ultrasound (US) and CD by DSC
▪ Experiments indicated that:
• EaB decreases due to ageing [1]
• E and CD stays constant
• PE remains its elasticity while loses its ability to withstand plastic
deformation [2]
9.4.2021 VTT – beyond the obvious 8
▪ Goals:
1. Simulate the ageing of PE and XLPE materials by the means of experiments and molecular dynamics (MD) simulations
2. Use this knowledge to improve non-destructive condition monitoring techniques (CMTs)
▪ Material model based on MD simulations have been developed:
• Methods to create and age representative material block [3]
• Simulation of stress-strain curves
• Simulation of E as function ageing [4]
• Simulation of CD as function of ageing [5]
• The model gives currently satisfactory approximates on
sound velocity values as material is aged
▪ Future work: role of the antioxidants in ageing model and
develop ultrasound and DSC measurements as CMTs
[1]
[2]
[3]
[4] [5]
Thank you for yourattention!