some recent research results and their implications … · some recent research results and their...

Some recent research results and their implications for RPV irradiation surveillance under long term operation

H. Hein, E. Keim, J. May, H. Schnabel

AREVA GmbH, Erlangen, Germany

IAEA Technical Meeting on Degradation of primary components of

Pressurised Water Cooled Nuclear Power Plants: current issues

and future challenges, 5-8 November 2013, Vienna, Austria

All rights are reserved, see liability notice. Some recent research results and their implications for RPV irradiation surveillance under LTO - IAEA Technical

Meeting - H. Hein - 5-8 November 2013 - AREVA GmbH Proprietary - RESTRICTED AREVA - © AREVA - AL: N - ECCN: N - p.3

Content

Introduction

Research Programs

CARISMA

CARINA

LONGLIFE

RPV Steels Studied

Discussion of Results

High Cu steels and flux effect

Late irradiation effects

High nickel effect

Low copper/nickel/phosporus material

Prediction by trend curves

Summary and Conclusions



Introduction

Reference temperature (RTNDTj, RTT0) is the parameter for the change

of material properties in terms of fracture toughness

RT increases with increasing fast neutron irradiation (fluence),

however in particular in the long term operation (LTO) mode the

measured data shows an increasing deviation from the predictions

Need to clarify impact of

Chemical composition (copper and nickel)

Neutron flux

Possible late irradiation effects

Microstructural examinations of tested irradiated RPV materials

provide insight into the irradiation induced changes of the material

matrix

To correlate the material properties with the microstructural data



Introduction

Original RPV materials used in PWR designed by former

Siemens/KWU company have been investigated in the CARISMA

and CARINA programs which were mainly focused on material

testing

Irradiated mainly in German test reactor VAK (Versuchsatomkraftwerk

Kahl) in the 1980s (neutron spectrum similar to German PWR)

Four of those RPV steels which are particularly interesting under the

point of view of long term irradiation behavior have been studied at

fluences up to 8×1019 n/cm2 (E > 1 MeV) in the European research

project LONGLIFE by various microstructural techniques

Atom Probe Tomography (APT)

Small Angle Neutron Scattering (SANS)

Transmission Electron Microscopy (TEM)

Positron Annihilation Spectroscopy (PAS)

Auger Electron Microscopy (AES)



Research Programs CARISMA/CARINA

Fracture toughness data base of pre-irradiated RPV materials and

assessment of the RTNDT and Master Curve concepts for RPV integrity

CARISMA (2003-2008)

“Determination of Fracture Mechanics Values on Irradiated Specimens

of German PWR Plants – Classification of the results into the

Master Curve concept”

CARINA (2008-2012)

“Extension of the Data Base for Fracture Mechanical Characteristics of

Irradiated German RPV Materials – Application of the Master Curve

Approach for Neutron Fluences in the Upper Bound”

More detailed information presented in

Hein, H., Keim, E., Schnabel, H., Seibert, T., Gundermann, A., “Final Results from the Crack Initiation

and Arrest of Irradiated Steel Materials Project on Fracture Mechanical Assessments of Pre-Irradiated

RPV Steels Used in German PWR,” J. ASTM Intl., Vol. 6 (2009), No. 7, doi:10.1520/JAI101962,

STP1513.

H. Hein, E. Keim, H. Schnabel, J. Barthelmes, Ch. Eiselt, F. Obermeier, J. Ganswind, M. Widera,

”Final Results from the CARINA Project on Crack Initiation and Arrest of Irradiated German RPV

Steels for Neutron Fluences in the Upper Bound”, 26th Symposium on Effects of Radiation on Nuclear

Materials, 12-13 June 2013, JW Marriott Indianapolis, Indianapolis, USA.



Research Programs CARISMA/CARINA

high Ni

high Cu

low Cu / medium Ni

high Ni

CARINA fluences and fluxes

(E > 1 MeV)

5.44×1018 to 7.67×1019 n/cm²

2.64×1010 to 2.55×1012 n/cm²s

RPV Material

German PWR

Generation

Material

Code

Cu

[%]

P

[%]

Ni

[%]

Mn

[%]

20MnMoNi5-5

JSW

4

(Konvoi) P142 BM 0.06 0.005 0.8 1.38

22NiMoCr3-7

JSW 3 P150 BM 0.05 0.008 0.83 0.84

22NiMoCr3-7

JSW 3

P150

HAZ - - - -

22NiMoCr3-7

Klöckner 1-2 P151 BM 0.09 0.006 0.96 0.81

22NiMoCr3-7

Klöckner 1-2

P151

HAZ - - - -

Molytherme

Electrode

Sulzer

2 P152 WM 0.02 0.014 0.09 1.51

S3NiMo1/OP41TT

GHH

4

(Konvoi) P142 WM 0.06 0.012 0.9 1.29

CA

RIN

A

S3NiMo3/OP41TT

Uddcomb 3 P16 WM 0.08 0.012 1.69 1.41

20MnMoNi5-5

JSW

4

(Konvoi) P141 BM 0.05 0.01 0.79 1.37

22NiMoCr3-7

Klöckner 1-2 P7 BM 0.12 0.02 0.97 0.72

22NiMoCr3-7

JSW 3-4 P147 BM 0.05 0.01 0.84 0.85

S3NiMo1/OP 41 TT

UP, GHH

4

(Konvoi) P141 WM 0.03 0.02 1.01 1.08

S3NiMo3/OP 41 TT

UP, Uddcomb 3 P16 WM 0.08 0.012 1.69 1.41

NiCrMo1

UP/LW320, GHH 2-4

KS05

WM 0.05 0.01 0.91 1.77

CA

RIS

MA

NiCrMo1

UP(modified)/

LW320, LW330

1 P370 WM 0.22 0.02 1.11 1.14

low Cu / Ni / P



Research Programs LONGLIFE

LONGLIFE (Treatment of long term irradiation embrittlement effects in

RPV safety assessment)

4 years collaborative research project launched in 2010 in the EURATOM

part of the 7th Framework Programme of the European Commission

Preselected RPV materials and congeneric model alloys

High fluence behavior

Neutron flux effect

Late Blooming Effect (LBE)

Effect of alloying and impurity elements

Thermal ageing

P-segregation and non hardening embrittlement

The experimental investigations in terms of material testing and

microstructural analyses are based on 16 pre-selected materials classed

into various RPV material groups with 7 base materials and 9 weld metals

Microstructure of some CARISMA/CARINA materials

analyzed in European LONGLIFE project



RPV Steels Studied

CARISMA/CARINA/LONGLIFE

Material Type Wire/powder

base material

Chemical Composition [wt.%]

C Si Mn P S Cr Mo Ni Cu V

P141 WM

(ANP-2)*

Weld

Metal

S3NiMo1/

OP41TT 0.05 0.12 1.08 0.019 0.009 <0.10 0.62 1.01 0.03 0.01

P147 BM

(ANP-4)* Forging 22NiMoCr3-7 0.21 0.22 0.85 0.006 0.006 0.39 0.55 0.84 0.05 <0.01

P370 WM

(ANP-5)*

Weld

Metal

NiCrMo1/

LW320/330 0.08 0.15 1.14 0.015 0.013 0.74 0.6 1.11 0.22 0.01

P16 WM

(ANP-6)*

Weld

metal

S3NiMo/

OP41TT/A 2 0.05 0.15 1.41 0.012 0.007 0.07 0.46 1.69 0.08 0.004

* LONGLIFE material code in brackets



Discussion of Results High Cu steels and flux effect

P370 WM - DT41: No flux effect, no saturation effect at lower fluences

0

20

40

60

80

100

120

140

160

180

0E+00 1E+19 2E+19 3E+19 4E+19

Fluence (E>1 MeV) [n/cm2]

DT

41 (

K)

P370 WM Cu=0.22%, Ni=1.11%

P370 B Cu=0.42%, Ni=1.11%

P370 C Cu=0.30%, Ni=1.11%

P390 WM Cu=0.27%, Ni=1.01%

2.1E12 cm-2s-1

6.1E10 cm-2s-1

SANS measurements performed

by HZDR Dresden



P141 WM

-50

-40

-30

-20

-10

0

10

20

30

40

50

0 1E+19 2E+19 3E+19 4E+19 5E+19

Neutron fluence (E > 1 MeV) [cm-2

]

T0, T

41 [

°C]

T0

T41

Discussion of Results Late irradiation effects

P141 WM - Fluence depending change in material properties (T41, T0)

confirmed by APT and SANS

APT measurements performed by Rolls-Royce

Mn/Ni/Si/Cu enriched clusters in P141 WM

irradiated to 5x1019 n/cm2


by HZDR Dresden

only clusters with P distribution



Discussion of Results High nickel effect

P16 WM - Fluence depending change in material properties (T41, T0)

confirmed by APT and SANS

-100

-80

-60

-40

-20

0

20

40

60

80

100

120

140

0E+00 1E+19 2E+19 3E+19 4E+19 5E+19 6E+19


T41,

T0 (

°C)

T41

T0

APT measurements performed by Rolls-Royce

Mn/Ni/Si/Cu clusters in 1.69 % Ni weld

P16 WM irradiated to 5.22x1019 cm-2

Material Fluence,

(1019

cm-2

) (E>1MeV)

Volume fraction,

c (vol%)

Number density,

N (1016

cm-3

)

Radius,

Rmean(nm)

T41

(°C)

0.41 0.047 22 1.9 -15

1.16 0.21 60 2.4 12

P16

WM

5.22 2.1 160 3.2 123


by HZDR Dresden



Discussion of Results Low copper/nickel/phosporus effect

P147 BM - Fluence depending change in material properties (T41, T0)

confirmed by SANS

-140

-120

-100

-80

-60

-40

-20

0

20

40

60

80

100

120

0E+00 1E+19 2E+19 3E+19 4E+19 5E+19 6E+19


T41,

T0 (

°C)

T41

T0


by HZDR Dresden



Discussion of Results Low copper/nickel/phosporus effect

P147 BM - TEM image under WBDF conditions (left) and reconstructed

size distributions from SANS (right) for 4.2x1019 n/cm2


by HZDR Dresden

TEM measurements performed

by CIEMAT

No dislocation loops were observed

throughout the sample



Discussion of Results Prediction by trend curves

The DT41 data measured for all four RPV steels have been compared

with well known prediction formulas (trend curves) which are

implemented in the ASTM E10.02 PLOTTER Tool

Reg. Guide 1.99 Rev. 2 Pos. 1

ASTM E 900 - 02

FIM Formula (Todeschini, EdF 900 MW)

Wide-Range Model WR-C(5)

Erickson CVE-Model

10 CFR § 50.61a (EONY)

JEAC4201-2007



►High copper

weld P370 WM :

Erickson

►High nickel P16

WM:

JEAC4201-2007

Discussion of Results Prediction by trend curves

►More data

points are needed

►Low Cu/Ni P141

WM and low

Cu/Ni/P P147 BM:

RG 1.99 Rev. 2,

EONY,

ASTM E900-02,

(JEAC4201)




Four RPV steels which are particularly interesting under the point of

view of long term irradiation behavior have been studied at different

irradiation levels up to 8×1019 n/cm2 (E > 1 MeV).

Material properties (T41 and T0) were compared with data obtained by

microstructural analyses techniques APT, SANS and TEM.

For all four materials the irradiation-induced change in material

properties could be confirmed.

DT41 data measured for all four RPV steels have been compared with

predictions by well known trend curves.

In this way the understanding of the material behavior induced by

neutron irradiation was improved and it was also shown that

microstructural examinations may serve as a valuable assistance to

the classical material testing in RPV irradiation surveillance

programs.




With respect to best practices for RPV irradiation surveillance programs following conclusions can be drawn from the study performed

Microstructural techniques such as APT, SANS, TEM and others are appropriate to investigate irradiation effects.

If RPV materials with high contents of copper or nickel are monitored then an almost linear increase of irradiation induced toughness reduction is expected with only a weak tendency of saturation if any.

If any potential impact of neutron flux and lead factor respectively is assessed, sources of uncertainty such as different neutron spectra have to be taken into account.

Late irradiation effects may occur occasionally, however reliable information is needed on the take out location of the specimens to exclude any significant material variability.

Even if significant uncertainty may occur at application of prediction formulas, it seems that there should be at least one trend curve which is able to predict the measured data with sufficient reliability. However, the challenge is to find the right one.

For well optimized RPV materials with comparatively low contents of Ni, P, and Cu the irradiation behavior can be predicted by most of the trend curves with acceptable margins.



Acknowledgment

The project CARISMA was supported financially by the VGB

(German utilities, NPP Gösgen), the German Ministry of Economics

and Technology (sponsorship number 1501284), NPP Borssele (The

Netherlands), and NPP Trillo (Spain) for that the authors are very

grateful.

The authors gratefully acknowledge the financial and technical

support of the VGB (German utilities), the German Ministry of

Economics and Technology (sponsorship number 1501357), NPP

Gösgen (Switzerland) and NPP Ringhals/Vattenfall (Sweden) for the

project CARINA.

The support of the LONGLIFE consortium, in particular Rolls-Royce

(UK), CIEMAT (Spain) and HZDR (Germany) for their microstructual

measurements, and the European Commission for the FP7-Fission-

2009 project LONGLIFE under Grant Agreement Number 249360 is

very much appreciated by the authors.



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End of presentation Some recent research results and their implications for RPV irradiation surveillance under long term operation

H. Hein, E. Keim, J. May, H. Schnabel

AREVA GmbH, Erlangen, Germany

IAEA Technical Meeting on Degradation of primary components of

Pressurised Water Cooled Nuclear Power Plants: current issues

and future challenges, 5-8 November 2013, Vienna, Austria

some recent research results and their implications … · some recent research results and their...

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