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French Association for
Design, Construction and Surveillance Rules
of Nuclear Power Plant Components
www.afcen.com
Association Française pour les règles
de conception, de construction
et de surveillance en exploitation
des matériels des Chaudières Electro-Nucléaires
IRRADIATION DAMAGE AND MATERIAL
LIMIT: ILLUSTRATION OF A WAY TO CODIFY
RULES WITH RCC-MRx CODE
Cécile Pétesch, Thierry Lebarbé CEA
Sophie Dubiez-Le Goff, Claude Pascal AREVA
Contents
 RCC-MRx presentation
 Code philosophy
 Consideration of irradiation effect in mechanical design rules
 Code approach
 Border lines
 Design rules
 Conclusion
IGORR 2014 17-21 November Bariloche Argentina
RCC-MRx, one of the Afcen Codes
RCC-E
Electrical – I&C
Systems and
components
ETC-F
Fire protection
BOARD &
Executive Committee
RCC-C
Fuel Assemblies
Editorial
committee
ETC-C
Civil Engineering
Structures
Training
committee
RCC-MRx
Design and
Construction Rules
HT/Irr. Mechanical
Components
IGORR 2014 17-21 November Bariloche Argentina
RSE-M
In-Service
Inspection rules
PWR Mechanical
components
RCC-M
Design and
construction of
PWR Mechanical
components
RCC-MRx Code Background
RCC-MR
 AFCEN Code
 components operating at
high temperature ASTRID
 Specificities: high
temperature, slender
structures
 2007 version Integrates
Iter VV + european
standards + new French
regulations (ESPN)
RCC-MX
 one CEA, Areva TA and Areva NP
Committee
 Irradiated components, Osiris,
Orphée, irradiation devices,JHR
 Specificities : irradiated structures,
aluminium and zirconium alloys
IGORR 2014 17-21 November Bariloche Argentina
Evolution of a conventional tensile stress-strain curve with
irradiation (316L(N) steel)
(MPa)
conventionnelle
Contrainte
(MPa)
Stress
Engineering
Instabilité(Load
plastique
Plastic instability
controlled)
800
700
diminution
avec l'irradiation
Decrease
of
pente
moins
Elongationraide
A
600
gt
500
400
300
200
Rupture
irradié
Irradiated
10.910.9
dpadpa(Strain controlled)
100
non
irradié
Unirradiated
0
0
5
10
15
20
25
Allongement (%)
Elongation
(%)
30
35
 2 issues to be addressed:
 The knowledge of the mechanical behaviour of the material when irradiated
 The rules used to prevent mechanical damage of the structures
IGORR 2014 17-21 November Bariloche Argentina
Design Rules for significant irradiation
 Mechanical codes prevent from the usual damages:







Excessive deformation
Plastic instability
Elastic and elastic-plastic instability
Progressive deformation
Fatigue
Creep
Fast fracture
 Possible methods:
 Direct verification:
• Experimental Analysis
• Elastic-plastic Analysis
 Elastic analysis:
• Detailed elastic analysis
• Simplified elastic analysis: use of flexibility and stress indices for standard components
IGORR 2014 17-21 November Bariloche Argentina
Irradiated material overall approach
 These multiple considerations led to an approach in three
steps for the definition of the rules to prevent irradiation
damage:
 First, mechanical characteristics depending on relevant irradiation
parameters have to be collected,
 Then the rules themselves have to be defined, considering the
consequences of the loss of ductility on the existing classical rules.
 Of course, this implies the definition of the border lines for the application
domain of the irradiated material prevention rules,
 The drivers for the use of the rules are the followings:
 Prevention of the mechanical damages of the structure
 Use of proven approaches and methodologies (Ramses, elastic follow-up)
 Easiness of use of the rules by designers.
IGORR 2014 17-21 November Bariloche Argentina
Code approach
 Effects of neutron irradiation on steels (316LN tensile curves)
Impact on parameters
relevant for
the mechanical design :

Rm ( t0)
Fluence
Rm ( t=0)
At(t0)
Agt( t0) Agt( t=0)
At(t=0)

Tensile strength
Yield strength
Ductility
Elongation at maximum
force
Swelling
Creep irradiation strain
 Decrease in the plastic adaptation challenges the secondary stress notion

IGORR 2014 17-21 November Bariloche Argentina
Code approach
Significant
irradiation?
NO
YES
MAXIMUM
ALLOWABLE
IRRADIATION
CURVE
Above rules are not
validated anymore
Design rules
without effect of
irradiation
Excessive deformation
Plastic instability
Fatigue
Progressive deformation
Fast fracture
NEGLIGIBLE
IRRADIATION
CURVE
Design rules
without effect of
irradiation
Above irradiation
has to be considered
Design rules with
effect of
irradiation
IGORR 2014 17-21 November Bariloche Argentina
Border lines
RCC-MRx subsection Z - Appendix A3
or Probationary Phase Rules
 Irradiation data supplied
A3.4 :
Basic
data
A3.5 :
Creep
data
A3.6 :
Irradiation
data
A3.8 :
Fracture
Mech. data
Non Alloy Steels (13 RPS in Tome 2)
 In Section III / Tome1 / Subsection Z /
Appendix A3
 Data given in function of parameters
considered as driven the material mechanical
behavior
 For
• Stainless steels (material mechanical behavior
driven by dpa NRT)
– A3.1S: X2CrNiMo17-12-2(N) solution annealed
(« 316L(N) »)
– A3.3S: X2CrNiMo17-12-2, X2CrNiMo17-12-3,
X2CrNiMo18-14-3 solution annealed (« 316L»)
– A3.4S: X2CrNi18-9, X2CrNi19-11 solution
annealed (« 304L »)
– A3.7S: X2CrNiMo17-12-2 around 20% work
hardening (« 316L work hardening»)
• Aluminum alloys (material mechanical behavior
driven by equivalent fluence in conventional thermal
neutrons (E= 0.0254eV), corresponding to the most
probable neutron energy in water at 20°C)
– A3.1A: 5754-O (solution annealed)
– A3.2A: 6061-T6 (structural Hardening)
• Zirconium alloys (material mechanical behavior
driven by irradiation flux in fast neutrons E>1MeV per
cm2)
– A3.1Z: Zircaloy 2
– A3.2Z: Zircaloy 4
A3.10NAS : P235GH
X
A3.11NAS : P265GH
X
X
A3.12NAS : P295GH
X
X
Alloy Steels (16 RPS in Tome 2, 4 RPS in RPP))
A3.11AS : 25CrMo4, 42CrMo4, 30CrNiMo8
X and
Bolts
A3.13AS : 16MND5
X
A3.14AS : 10CrMo9-10 fully annealed
X
X
A3.15AS : 13CrMo4-5 quenched and tempered
A3.16AS : 2.25% Cr, 1% Mo normalised tempered or
quenched tempered
X
X
X
X
A3.17AS : X10CrMoVNb9-2 quenched tempered
A3.18AS : X10CrMoVNb9-1 normalised tempered or
quenched tempered
X
X
X
X
A3.19AS : Eurofer X10CrWVTa9-1 normalised tempered
X
Stainless Steels (25 RPS in Tome 2)
A3.1S : X2CrNiMo17-12-2(N) solution annealed
X
X
A3.2S : X6CrNi18-10 et X5CrNi18-10 solution annealed
X
X
A3.3S : X2CrNiMo17-12-2, 17-12-3, X2CrNiMo18-14-3
X
X
A3.4S : X2CrNi18-9, X2CrNi19-11
X
X
X
X
A3.7S : X2CrNiMo17-12-2 around 20% work hardening
X and
Bolts
X
A3.8S : X4CrNiMo16-05-01 quenched and annealed
X and
Bolts
A3.10S : X6NiCrTiMoVB25-15-2 heat treated structural
hardening
X and
Bolts
X
X
X
A3.1A : 5754-O
X
X
X
A3.2A : 6061-T6
X
X
X
A3.1Z : Zircaloy 2
X
X
X
A3.2Z : Zircaloy 4
X
X
X
A3.6S : X15CrNiW22-12 solution annealed followed by aging
X
X
X
X
Special Alloys Ni-Cr-Fe (5 RPS in Tome 2)
A3.5SA : X5NiCrTiAl33-21 after annealing heat treatment at
980°C
Aluminium alloys (7 RPS in Tome 2, 1 RPS in RPP)
Zirconium alloys (4 RPS in Tome 2)
IGORR 2014 17-21 November Bariloche Argentina
X
Drivers for the border limits
Negliglible
irradiation
Maximum allowable
irradiation
A3.1S: « 316L(N) »
 Ductility
 Swelling
A3.3S: « 316L»
 Ductility
 Swelling
A3.7S: « 316L work hardening»
 Ductility
 Swelling
A3.4S: « 304L »
 Ductility
Not supplied
A3.1A: 5754-O (solution annealed)
Ductility
Ductility
A3.2A: 6061-T6 (structural Hardening)
 Ductility
Ductility
A3.1Z: Zircaloy 2
Ductility
Ductility
A3.2Z: Zircaloy 4
Ductility
Ductility
IGORR 2014 17-21 November Bariloche Argentina
Design Rules for significant irradiation
Rules to be met without irradiation effect
Excessive deformation, plastic instability
Pm  S m
PL  1.5  Sm
PL  Pb  1.5  Sm
Additional rules to integrate the irradiation
effect
Excessive deformation, plastic instability
Pm  Qm  S
A
em
PL  Pb  Q  F  SetA
Fast fracture
J(a,C)≤ JIC
Fast fracture
J(a,C)≤ JIC (irradiated)
Progressive deformation
Progressive deformation
P and Q to compare to kSm
Analyse non irradiated material
Fatigue
Fatigue
Usage factor V = specified Ncycles / allowable
Ncycles < 1
Creep
Creep factor U or W ≈ application time /
allowable time < 1
Fatigue curve without irradiation:  increases
Creep
For stainless steel only, Creep factor U or W ≈
application time / allowable time < 0.1
IGORR 2014 17-21 November Bariloche Argentina
Elastic follow up methods
 Good accuracy of plastic stress using elastic analysis
IGORR 2014 17-21 November Bariloche Argentina
Design Rules for significant irradiation
Principle of determination of Sem and Set
SemX and SetX are « materials » limits, functions of irradiation G, temperature q, level of criteria X, and stress
redistribution factor r
G dependant on materials (dpa, fluence of fast or thermal neutrons,…)
Exact formulas

Se(C)
B : instabilité plastique sous chargement
mécanique – Eprouvette cylindrique
SSet(C*)
e(C*)
C : instabilité plastique sous chargement
avec effet de ressort
Slopede=ressort”
-E/r
Droite “Effet
r = 0-E/r
: strain controlled
Pente
r : facteur
de ressort
r = ∞ : d’effet
load controlled
Sem(B)
B
Rm
 Rm, At, Agt, ep(Smx) are dependent on G
(irradiation) and θ
 r has to be determined (r=3 is generally a
good value except for pipes)
 kX is the design margin (2.5, 2, or 1.35)
 kB=1 for brittle materials, 1.5 for ductile
(general formula given in A3.GEN)
C*
A
C
1
3
2
Agt
Rr
D
4
Af=( Agt +At)/2
At
A%
IGORR 2014 17-21 November Bariloche Argentina
Feedback of use and challenges, since
the first edition of the RCC-MX, in 2005
 The feedback of their application showed the following:
 For research reactors,
• despite the efforts for the clarity and simplicity of the rules. They have to be
explained and completed for creeping under irradiation.
• irradiation program completing the data is to be continued.
 The RCC-MRx is also used by projects of new nuclear facilities types such
as MYRRHA, ESS, and ITER.
• new phenomena that may challenge the material properties (such as He
production) and the irradiation boundaries and challenge the conservatism of the
rules.
• For each of these new cases, the rules, irradiated material properties and
irradiation boundaries have to be reanalysed in view of the justification of their
applicability.
 Some improvement work is considered as regards the
definition and the applicability of the existing rules.
IGORR 2014 17-21 November Bariloche Argentina
Concluding remarks
 Irradiated material rules issued from RCC-MX 2005 have now been used for several
years for the JHR project and for periodic safety assessment of other existing reactors
 Wdely applied within the French research reactor community and known by the nuclear
safety authority and its TSO
 Important breakthrough in line with well-known and proven methods and practices.

 These set of rules defined for research reactors and fast-breeders includes:
 The irradiated material data and bounding limits dealing with negligible irradiation and maximal irradiation.
 Design analysis rules using elastic analysis aiming at providing the designers with prevention of mechanical
damages leading to the failure of the mechanical components.
 Effort is to be continued regarding:
 The experimental irradiation programs aiming at providing the RCC-MRx with data for ensuring the
completion of irradiated materials characteristics.
 The explanation and training of the designers
 The completion and simplification of the rules aiming at tailoring the coverage of damage prevention and
easiness of use by the designers.

 This set of rules is subject to a strong interest from several currently designed or
constructed new nuclear facilities such as MYRRHA, ITER, ESS.
 To become fully applicable for these facilities, the rules should be clarified regarding their domain of
relevance and justification of the relevance and completeness is to be improved.

 These unique set of rules is included in the RCC-MRx 2012 (English version).
IGORR 2014 17-21 November Bariloche Argentina
French Association for
Design, Construction and Surveillance Rules
of Nuclear Power Plant Components
www.afcen.com
Association Française pour les règles
de conception, de construction
et de surveillance en exploitation
des matériels des Chaudières Electro-Nucléaires
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ATTENTION