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AREVA NP GmbH - Elisabeth Keim - NTCMF-G, Erlangen / Reginal Workshop on Structural Integrity on LWR, Belo Horizonte, Brazil, 23-26 June 2009AREVA NP All rights are reserved, see liability notice. 1


Life Extension Program for Western Europe Nuclear Power Plants -

Using the Example of NPP Borssele

Elisabeth Keim, Julia BarthelmesAREVA NP GmbH, Germany

André de JongEPZ Netherlands

The reproduction, transmission or use of this document or its contents is not permitted without express written authority. Offenders will be liable for damages. All rights, including rights created by patent grant or registration of a utility model or design, are reserved.

3AREVA NP All rights are reserved, see liability notice.AREVA NP GmbH - Elisabeth Keim - NTCMF-G, Erlangen / Reginal Workshop on Structural Integrity on LWR, Belo Horizonte, Brazil, 23-26 June 2009

Content

> Introduction of NPP BorsseleHistory

Current status

> Assessment of the RPV Regarding OperationThermal ageing

Irradiation induced ageing

> Changes in Regulatory and Praxis> Requirements for Life Extension KCB> Procedure for Life Extension> Additional Irradiation Surveillance Program

Testing SOP 0a

Manufacturing of additional irradiation sets

Fluence calculations

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Content


Current status




Testing SOP 0a



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History of NPP Borssele> Siemens PWR > 1973:

1st criticalityNeutron fluence calculation of RPV inner sideDesign fluence after 32 EFPY: 3.5E19 n/cm² with standard core loading Change to Low-Leakage actual fluence less than design fluence

> 1976: withdrawal of irradiation capsule SOP 1> 1978: withdrawal of irradiation capsule SOP 2

Neutron fluence calculation of SOP 1 and 2Determination of fluence not for E > 1 MeV KWU made estimations


History of NPP Borssele

Irradiation Surveillance Program

• Determination of RTNDT, ∆T41, RTNDTj

Values better than design fluence• Safety of RPV

- Maximum allowable RTNDT = 31 °C - Weld metal is leading RTNDTj of WM = 9°C

Safety against brittle failure of RPVfor EOL proven

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History of NPP Borssele

> 2006: agreement between government and plant owners on extended operation by 2034 (60 years of operation)

> 2007: new RPV surveillance program realizedState of the art approach: both established (Charpy-V/RTNDT) and new (fracture toughness/Master Curve) conceptsInsertion of both new irradiation sets SOP 3 and 4 in RPV duringrevision 09/2007New un-irradiated set of specimens manufactured and tested

> 2008: Comprehensive neutron fluence calculations SOP 2, 3, 4 and RPV inner side


Current status of NPP Borssele

> In October 2013 KCB will reach 40 years of operation time

> For these 40 years a formal verification based on the results ofSOP 1 and SOP 2 exists

New surveillance program and improved fluence calculations are needed as well as a state of the art RPV integrity analysis

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Content


Current status




Testing SOP 0a



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Thermal Ageing

> Thermal ageing dependent on Cu content of material

> Cu is deemed to be initiator for precipitation

> Cu content KCB RPV

BM: 0,04 wt%

WM: 0,09 wt%

> No thermal ageing at Cu < 0,25 wt% and T < 325°C

> Cu content in KCB RPV materials < 0,2 wt%

> Mean value for irradiation temperature at 305°C

Thermal ageing for KCB RPV can be neglected

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Irradiation Induced Ageing (1)

> Changes in material behavior due to neutron irradiation

> For KCB RPV use of RTNDT concept

> Quantity for changes in material behavior is ∆T41

> Assessment of irradiation induced ageing via RTNDTj

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Ausgangs-zustand

RTNDT (°C) ∆T41 (K) RTNDTJ (°C) ∆T41 (K) RTNDTJ (°C)Ring 03 -10 9 -1 12 2Ring 04 -20 17 -3 18 -2

WEZ -5 11 6 24 19Schweiß-

gut -45 34 -11 40 -5

15 VLJ 1.6E19 n/cm2

17 VLJ 1.9E19 n/cm2

SOP1 (KWU-Bewertung)

SOP2 (KWU-Bewertung)

Ausgangs-zustand

RTNDT (°C) ∆T41 (K) RTNDTJ (°C) ∆T41 (K) RTNDTJ (°C) ∆T41 (K) RTNDTJ (°C) ∆T41 (K) RTNDTJ (°C) ∆T41 (K) RTNDTJ (°C)Ring 03 -10 8 -2 9 -1 12 2 16 6 20 10Ring 04 -20 13 -7 17 -3 18 -2 26 6 31 11

WEZ -5 16 11 11 6 24 19 33 28 41 36Schweiß-

gut -45 27 -18 34 -11 40 -5 54 9 65 20

Extrapolation

9 VLJ 1E19 n/cm²

15 VLJ 1.6E19 n/cm2

17 VLJ 1.9E19 n/cm2

32 VLJ 3.5E19 n/cm2

48 VLJ 5.25E19 n/cm2

Extrapolation SOP1 (KWU-Bewertung)

SOP2 (KWU-Bewertung) Extrapolation



Extrapolation of RTNDTj

-50

-40

-30

-20

-10

0

10

20

30

40

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

Fluence (n/cm2)

Ring 03, measuredRing 04, measuredHAZ, measuredSG, measuredRing 03, extrapolatedRing 04, extrapolatedHAZ, extrapolatedSG, extrapolatedPTS LimitSOP 1 KEMASOP 2 KEMA

32 VLJ48 VLJ

SOP 115 FPY

SOP 217 FPY

9 VLJ

RT N

DTj

(°C

)

HAZ not representative because higher Co content of weld


Content


Current status




Testing SOP 0a



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Changes in Regulatory and PraxisSince Start of Operation of KCB 1973 (1)

> Sampling direction today transversal (T-L) to the main forging direction

> HAZ is no longer safety related since it is covered by the base metal

> Performance of notched impact test only instrumented

T

S

L

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Changes in Regulatory and PraxisSince Start of Operation of KCB 1973 (2)

> KTA 3203/01 (replaces KTA 3203/84):„Surveillance of the Irradiation Behaviour of Reactor Pressure Vessel Materials of LWR Facilities“

Alternative to the direct use of ∆T41 a RTlimit curve is used as a base

RTlimit :The limiting value for the reference temperature RTlimit is the highest reference temperaturewhich is based on the proof ofsafety against brittle failure

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Changes in Regulatory and Praxis Since Start of Operation of KCB 1973 (3)


Changes in Regulatory and Praxis Since Start of Operation of KCB 1973 (4)

Possible validation of RPV using Pellini- and Charpy-V tests according to RTNDT concept (indirect verification)

Possible validation of RPV using directly measured fracture mechanics values according to RTT0 concept

RTNDT concept and RTT0 concept:

• Equivalent use of both concepts

• indirect determination of RTNDT, direct determination of RTT0 using fracture mechanics tests

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Content


Current status




Testing SOP 0a



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Requirements for Life Extension KCB (1)

> A life extension to 60 operation years is possible if an appropriate proof of safety is shown

> Requirements for life extension to 60 operation years

Specimen fluence from irradiation surveillance programs is related to the RPV fluence after 60 operation years

RTNDTj and RTT0, respectively < RTNDT allowable

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Temperature

Load

Material

∆T



> RTNDT allowable :Intersection of material and stress curve

> RTNDT allowable = 31°C

(according to the state of currently valid stress curves of 1985)


Content


Current status




Testing SOP 0a



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Procedure for Life Extension (1)

> Transformation of CARISMA results on KCB RPV

Due to similar CARISMA and KCB material concerning chemicalcomposition and mechanical properties possible transformation

> Anew calculation of current fluence of RPV and SOP 2, scraping samples

> Alternative neutron sources

> Irradiation of further specimen set inside the KCB reactor

Urgency to prove safety until 2013

New calculation for lead factor of KCB irradiation channels

possible necessity for two further specimen sets

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> MaterialAvailability of unirradiated remaining material of KCB RPV

Enough material (BM and WM) for further specimen sets available

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Specimens

Provision of specimens for RTNDT concept

Provision of specimens for RTT0 concept

Achieving this strategy by using

• Cv compact specimens

• Fracture mechanics specimens, bending and/or CT specimens or prefatigued cv specimens

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Irradiated specimen sets

Use of unirradiated specimens

Testing of transversal specimens (T-L)

Determination of T0 and RTNDT, respectively

Material selection:

• Use of specimens from the core shells 03 and 04 as well as the work sample W03 (weld seam)

• Use of HAZ specimens not required from the updated regulatory

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Unirradiated specimen set

Testing of transversal specimens (T-L)

Determination of T0 and RTNDT, respectively

Material selection:

• Use of specimens from the core shells 03 and 04 as well as the work sample W03 (weld seam)

• Use of HAZ specimens not required from the updated regulatory

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Specimen Number acc. to KTA 3203 (RTNDT concept):

Additional Specimen (RTT0 concept):

Tensile Specimen

Charpy-V-Specimen

3 PB-Specimen

SOP 3: 12 SOP 4: 12 unir: 12

∑ 36

SOP 3: 3 SOP 4: 3 unir: 3

∑ 9

SOP 3: 10 SOP 4: 10 unir: 10

∑ 30


Content


Current status




Testing SOP 0a



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Testing SOP 0a

> Change in orientation of Tensile and Charpy-V specimens for BM (SOP 0: L-S; SOP 0a: T-L)

Only influence of specimen orientation on the upper shelf energy

> Additional T0 testing of core material

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Testing SOP 0a

> Evaluation of RTNDT

NDT-T from the Pellini drop weight testTAV(68J) - 33K and TAV(0,9mm) - 33K from Charpy test

Influence of specimen orientation on TAV(68J) - 33K and TAV(0,9mm) - 33K

The values for RTNDT up to now are still valid

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Manufacturing of Additional Irradiation Sets (1)

One capsule holder for each setTwo standard irradiation capsules (20x30x486 mm) per set and holder

four irradiation capsules containing

• original RPV material of the core shells 03 and 04

• of the work sample of the weld AW 03.1

• all in all 25 specimens per set

Fabrication of two irradiation sets (SOP 3 and SOP 4):

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Charpy Specimens

Tensile SpecimensFracture Toughness Specimens



50 cm

Irradiation column

Insertion position of the columns

Insertion of the irradiation capsules in September 2007



> Withdrawal of SOP 3 and SOP 4

Based on the requirements to show a proof of safety until 2013 and the estimated lead factor it is recommended to use two irradiation specimen capsules• Withdrawal of SOP 3 in 2013

• Withdrawal of SOP 4 after 2013 when achieving the RPV fluence for 60 years

• Intermediate proof by extrapolating and transformation of results from CARISMA and other data on KCB

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> Specimen sets

Basis: safety regulation KTA 3203, 06/01

BM: Base metalWM: weld metal

≥ 100 % Assessment fluence3331212123

~ 50 % Assessment fluence3331212122

unirradiated3331212121

WMBM IIBM IWMBM IIBM I

WithdrawalTensile specimensCharpy-V SpecimensSpecimen set number

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Main Steps

> Checking the intactness of the irradiation channels> Preparation of documents and release by regulatory > Provision of materials> Manufacturing of specimens

Unirradiated setIrradiated sets

> Manufacturing and loading of capsulesManufacturing of capsule piecesTesting work samplesLoading with specimens, filling material,temperature monitors,neutron fluence detectors Closing and testing of capsules

> Manufacturing of specimen columns> Packing and transport> Insertion KCB

End capFilling material Temperature monitors

NbFe Detector

Temperature monitors

FeNb Detector

Filling material

Irradiation diraction

Capsule sheet

Capsule draft


Fluence Calculations (1)

> Innovations of fluence calculations:

Use of neutron sources pin by pin (205 Values per FE, before 9 Values)

More precise calculation of neutron source (CASCADE-3D)

Use of more detailed geometric models for the neutron transport calculation

3D performance of the neutron transport calculation due to higher capacities of the processors

Improvement of the accuracy of results for the theoretical neutron fluence

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> Fast neutron fluence (E > 1 MeV) calculation at the RPV inner side for operating cycle 1 to 33

> Fast neutron fluence (E > 1 MeV) calculation for the irradiationcapsules SOP 2, SOP 3 and SOP 4

> RPV fluence extrapolation based on the flux average of cycle 31 to 33

Maximum fluence (E > 1 MeV) at the inner side of RPV will reach3.22E19 n/cm2 after 55 EFPY

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calendar year

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extrapolation withaveraged data fromcycle 31 to 32 (33)

cycle no.



> Theoretical and experimental fluences of SOP 2 have been compared

Nb detectors

• systematically too low compared with theory• are not reliable

Fe detectors

• show better agreement, but…• unexpected wide range of values compared with theory• only few values statistical treatment problematic

In order to get a better validation of the theoretical fluence via experiment the taking of scraping samples is recommended

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Fluence Calculation - Scraping Samples


Summary

> In October 2013 KCB will reach 40 years of operation time

> For these 40 years a formal verification based on the results ofSOP 1 and SOP 2 exists

> In June 2006 KCB received the approval to apply for a plant life extension to 60 years of operation

> Necessary: verification of a safe operation during the plant life of 60 operation years

new surveillance program: SOP 0a tested, SOP 3 and 4 implemented

improved fluence calculations performed

scraping samples for fluence status

state of the art RPV integrity analysis underway

status report for proof of RPV integrity for 60 years

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