MATTINO*
Activities on
Nuclear Materials Research
*MATerials performance assessmenT for
safety and Innovative Nuclear reactOrs
Karl-Fredrik Nilsson
Our Main mission is Materials and components related
safety issues for present and future reactors
Standardisation
Increased emphasis
Safety
reference
Basic research into materials
performance characterisation
Modelling & Simulation
SNETP: The 3 Pillars
SNETP is central for our activities
NC2I
NUGENIA
ESNII, EERA JPNM

NUGENIA: Maintain safety and
competitiveness of today’s
technologies

NC2I: Enlarge nuclear fission
portfolio beyond electricity
production (heat)

ESNII/EERA JPNM: Develop
Gen IV Fast Reactors with
closed fuel cycle to enhance
sustainability and to
minimize waste
Examples of Activities
1. Experimental Activities
•
•
Stress corrosion cracking
Small Punch Test
2. Experimental and modelling
•
•
Thermal Fatigue of pipes
Residual stresses in welds
3. Model development
•
•
Multi-scale and physics based models
Simulation of fuel cladding in accident scenario
4. Codes, Standards & Harmonization
•
•
European Design Codes
Materials Database MatDB
Stress Corrosion Cracking (AMALIA)
Why?
irradiation
damage
damage
interaction
thermo-mech.
loading
chemical
attack
Stress corrosion cracking is one of the major failure
mechanism in power plants
 need for environmental testing incl. in-pile
experiments, collaboration with VTT, ITU, NRG, CV
Rez
3 recirculation loops with full water
chemistry control, equipped for
environmental mechanical tests at
pmax = 360 bar, Tmax = 650°C: =>
BWR, PWR, SCWR conditions
Under construction:
Liquid lead recirculation loop for
- Corrosion
- Erosion
- Stress corrosion cracking
At Tmax = 700°C, vmax = 5 m/s
Small Punch Test
Why?
Need for fast “semi non-destructive ” test method for small specimen
•
•
•
Possibility to obtain creep resistance data from small amounts of material
Characterization of material response to multi-axial loading
Characterization of anisotropy in mechanical properties
SP test specimen, 8mm
diameter, 0.5 mm thickness
Main principle of
small punch test
SP creep tests were
carried out in accord
with the CWA 15627
Code of Practice, at
650°C in an Ar
atmosphere.
Application to P91 weld
INTEGRITY of repair welds Project
4-point bend (75.89 kN)
+ internal pressure (160 bar)
at 600 °C for 5000 h
INTEGRITY Pipe
BM - Base material
WM - Weld material
HAZ material:
(FG Fine grained,
CG Coarse grained)
SE - Service
exposed*
* Service exposed conditions: 60kh at 565 oC under pressure of 250 bar
Application to P91 weld
• The weakest zone is
clearly the fine grain
HAZ where type IV
cracking often occurs
in plant components
SP stress rupture results for all
weldment zones
Thermal Fatigue in Nuclear Components
Why?
Thermal fatigue is one of the major degradation mechanisms. Complex loadings is
a main issue.
• Procedures for thermal fatigue initiation (NESC) and propagation
(NUGENIA) by replacing the load spectrum with the single frequency
load that gives the shortest life
• Experimental Programme to simulate thermal fatigue damage
through cyclic down shocks
Experimental set-up for Thermal fatigue tests
Axial loading train
Water
quenching
lines
• Thermal loads:
Induction Heating
and cooling by
water
• Mechanical Load:
Axial load (0, 50,
100 kN)
Thermal Fatigue in Nuclear Components
The initiation of cracking and depth
of cracks is monitored by NDT
Computed and measured crack depth vs #
of cycles for 300°C and 550°C
15
Hut&Picker 550 C
14
Replica technique for crack
initiation (surface cracking)
crack depth, mm
12
10
8
Hut&Picker 300 C
6
4
2
Time-of-Flight Diffraction for
crack sizing
0
0
0.5
1
1.5
cycles, N
2
2.5
3
5
x 10
Residual Stresses in welds
Why?
Welds are weak spots in components.
For assessment we need to know:
• Residual stresses
• Material variability and defects
Measured vs. computed
• In MATTINO we perform:
•
Residual stress measurements with neutron
diffraction and synchrotron diffraction
•
Analyses with different levels of refinement
Initial
Spiral slit technique in synchrotron
diffraction stress measurement:
Refined
Research Front: Multi-scale Models (Crystal
plasticity models)
Why?
• Material degradation occurs at different “length and size scales”
• Necessary to extrapolate form accelerated tests to operational conditions
• Basis for development of new materials (e.g. nano materials)
Fatigue initiation and
short crack growth
Dislocation
patterning
IGSCC-Multiscale modelling
• Surface reconstruction


Real grain topology
Simplification
• Conformal meshing:


Surfaces
Volumes
• Constitutive models:


Grains: AE+CP
Grain boundaries: cohesive zone
Experimental data University of Manchester: http://dx.doi.org/10.1016/j.commatsci.2010.12.014
13 April 2015
14
Model development
• New Model development & implementation in Codes
• Strain gradient effects
• Non-convex free energy (leads to instabilities)
• Grain boundary model
10
10-1
10-3
Computed variation in stress-strain curves for
different loading rates caused by dislocation
patterning
Patterning from
non-convexity
Fuel pellet clad interaction (sub-assembly blockage)
Why? Fuel cladding is the first safety barrier. Safety assessment requires
modelling of the fuel and cladding for relevant loads
• Assessment of the behaviour of fuel pin
sub-assembly blockage (GFR)
• Two-step analysis:
Von Mises stress distribution in
fuel and cladding
13 April 2015
•
CFD  temperature transients
•
FEM fuel-pin (cracked fuel and cladding)
Computed hoop strain cladding
Computed K vs. crack
depth (different crack
aspect ratios)
16
Contribution to Codes & Standards
Examples:
• Code of Practice Small punch
test (CEN/CENEL)
• European Procedure HighCycle Thermal Fatigue
(NESC/NULIFE)
• Design & Construction Code
for mechanical Equipment of
innovative nuclear
installations (CEN/CELEC)
• Feasibility Study to develop
standardized rules for the
design and construction of
Gen IV reactors (DG-ENER)
MATTER Project
• 7th Framework EURATOM project
• Development of Test procedures and Design Rules in
support of Design & Construction of ESNII Reactors
• Three Domains
• D1: Screening Test procedures and material
characterization tests for MYRRHA
• D2: Design Rules for ASTRID, Gr 91 steel (creep-fatigue,
ratchetting, negligible creep, welding, thermal ageing..)
• D3: Management of EERA JPNM
Workshop on Env. Degradation effects &
Design Codes for heavy liquid metal reactors
In the MATTER Description of Work
• Original idea: presentation of progress in MATTER Design
Code related Work Packages (WP 4 – 6) (high-temperature
issues)
• More urgent need to discuss Design Rules for heavy liquid
metal alloys (CEN WS/64 Feasibility Study)
When; Second Quarter 2013
Where: Petten
Duration 1,5 days
MATTER WS HLM Env. Degradation & Design Codes
Topics to be addressed:
• Design and material and component requirements for ALFRED
and MYRRHA (partly already covered by MATTER
Deliverable and last year's Workshop)
• Degradation mechanisms for lead and lead-bismuth
• Mitigation mechanisms (coatings, environment control, etc)
• Requirements/needs for environmental degradation sections
in Design Code (RCC-MRx as basis) (e.g. priorities of specific
data)
• Proposal for outline of Design Factors and structure of Design
Code for HLM environmental effects
Who should attend?
• Experts in environmental degradation HLM
• Reactor Designers
• User and developers of Codes
• Generalists in environmental effects & Design Codes
Confirmed participation (ALFRED/MYRRHA Development ESNII):
ENEA, KIT, KTH, SCK•CEN, JRC, NRG?, ANSALDO?
Confirmed participation (Design Code): RCC-MRX/AREVA
Confirmed participation: D. Tice (AMEC, ASME and LWR)
Invitation sent: (IPPE/Obninsk)
Exact Dates not fixed: main reason waiting for response from IPPE
MatDB—Overview
•
MatDB is an online database application for preserving and
exchanging engineering alloys data
•
The facility is based on an enduring data model established more
than 30 years ago through the joint efforts of NIMS, NIST, and the
JRC
Material entity
Chemical composition
Designation & production
Characterisation
Isotropic grain size
Duplex grain size
Directionally solidified grain size
Hardness
Microstructure
Phase
Physical constants
Thermo-mechanical heat treatment
Customer internals
MatDB—Purpose
• Support to nuclear safety policy
• IAEA embrittlement data
• Safeguard data
• Data relevant to MYRRHA from former FBR and HTR research
programmes
• Support to Euratom indirect actions
• Data management
• Data exchange
• Reuse
• Development of new testing Standards, such as creep-fatigue and
small punch
• Validation of models
•
MatDB—Activities
• I-NERI Materials Database Interoperability project
• Enable data transfer between MatDB and the GenIV Handbook hosted at ORNL
• Migration of the IAEA Surveillance Database
• Transfer more than 40.000 data sets to the IET materials database
• Development of ICT Standards for database interoperability
• Enable systems interoperability in the engineering materials sector by developing
Standard messaging formats for data transfer
• Work performed in the framework of the European Committee for Standardization
(CEN), IET awarded lead role in CEN/WS SERES, a 2-year CEN Workshop on
Standards for electronic reporting in the engineering sector
• Data citation
• Data cite DOIs assigned to individual data sets to allow citation and reuse