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Technical Meeting on the

Dissimilar Metal Welding Experiences and Lessons Learned

Ana Rosa Baliza Maia

The participation of QA department in the activities

related to dissimilar metal welding in Angra 1



Energy Matrix in Brazil

The participation of QA department in the activities related

to dissimilar metal welding in Angra 1

Hydroelectric energy, 71%

Natural Gas, 11%

Wind, 1%

Nuclear, 3%

Biomass, 8% Petroleum

products, 4% coal, 2%



Where we are:

Angra 1 – 640 MWe

Angra 2 – 1367 MWe

Angra 3 - building



Introduction:

• In Angra 1 many activities have been done to inspect, monitor and

mitigate dissimilar welds.

• The QA department monitors all these activities with the objective of

verify that the normative bases adopted are in accordance to the

approved documents by the Brazilian regulatory body – CNEN and

applicable international standards.





Standards Requirements

• Angra 1 NPP was designed and built by Westinghouse, the rules of the U.S.

NRC (United States Nuclear Regulatory Commission) are adopted in

conjunction with the rules of CNEN. This statement is based on the

requirements of the CNEN NE 1.04 standard:

"6.5.1 - Items must be designed, manufactured, assembled, built, tested and

inspected in accordance with standards compatible with the importance of the

safety function to be performed.

6.5.2 - In applying the provisions of section 6.5.1, shall be adopted current

Brazilian codes and standards. When Brazilian standards could not be used,

preferably, Codes, Guides and Recommendations of the International Atomic

Energy Agency shall be used and, in their lack, international standards shall be

used, provided that such rules and regulations are accepted by CNEN”





Standards Requirements

Eletronuclear in accordance with CNEN NN - 1.16 - "Quality

Assurance for Safety of Nuclear Power Plants and other

facilities" implemented a Quality Management System - QMS,

valid for all its utilities.

This standard has the same 18 BR of 10 CFR 50 App B.



Appendix B to Part 50 - Quality Assurance Criteria for

Nuclear Power Plants and Fuel Reprocessing Plants



The 18 Basic Requirements I – Organization

II - Quality assurance program

III – Design control

IV – Procurement Document control

V – Instructions, procedures and drawings

VI – Document control

VII – Control of purchase material, equipment, and services

VIII – Identification and control of materials, parts and components

IX – Control of special processes

X – Inspection

XI – Test Control

XII – Control of measuring and test equipment

XIII – Handling, storage and shipping

XIV – Inspection, test and operation status

XV – Nonconforming materials, parts, or components

XVI – Corrective action

XVII – Quality assurance records

XVIII - Audits





Dissimilar Weld Standards

Appicable to Angra 1



The in-service inspection program of the Angra 1 NPP is updated every 10 years,

according to 10CFR 50.55a, ASME section XI and CNEN NE 1.25:

CNEN NE 1.25 requirement 2.2.2 : "In addition to the requirements of this Standard, the

implementation of in-service inspection programs shall comply with the standards or

codes established by the operating organization in the technical specifications of the Final

Safety Analysis Report, in accordance with the guidance of the designer and CNEN

approval.”

(*) There is not Ap VIII – PDI, There is not special UT inspection for Dissimilar Weld

(**) There is Ap VIII – PDI, There is special UT inspection - EPRI procedures

Interval of 10 years Date Section XI edition

1st Inteval 01/01/1985-31/05/1996 1981(*)

2nd Interval 01/06/1996-31/05/2006 1989 (*)

3rd Interval 01/06/2006-31/05/2016 2001 ad 2002 and 2003(**)

4th Interval 01/06/2016-31/05/2026 2007 AD 2008 (**)



Utilities have followed the required ASME Code Section XI examination:

• Welds ≥ 4 Inch NPS - Visual, Surface and Volumetric

• Welds > 1 Inch NPS and < 4 Inch NPS - Visual and Surface (Volumetric for HPI)

• Welds ≤ 1 Inch NPS - Visual Only

• Table IWB-2500-1 of Section XI requires that 100% of dissimilar metal vessel nozzle-

to-safe end welds (Category B-F) and dissimilar metal piping welds (Category B-J) be

included in the percentage requirements of Note 1 (Table IWB-2500-1, Category B-J)

and be inspected at 10-year intervals.

• Essentially all of the key Alloy 82/182 pipe welds are dissimilar metal welds joining

low-alloy or carbon steel nozzles to stainless steel pipe. Accordingly, most Alloy

82/182 butt welds have been inspected to the visual, surface, or volumetric

examination requirements noted above, depending on the nominal pipe size.

Dissimilar Weld Inspection according to ASME Code Section XI:



Volumetric Examination: Improvements After 1990

Supplements in Appendix VIII (Performance Demonstrations for Ultrasonic Examination

Systems) of ASME Code Section XI address specific components such as piping welds, vessel

welds, vessel nozzles, and bolting.

Supplement 10 of Appendix VIII addresses UT of dissimilar metal welds and was incorporated

into 10 CFR50.55a, requiring implementation by November 22, 2002.

All dissimilar metal weld examinations after that date have been required to be performed with

Appendix VIII qualified procedures, personnel and equipment.

ETN uses ASME Section XI and 10 CFR 50.55a and:

Supplement 10 - Qualification requirements for dissimilar metal piping welds.

Generic procedure PDI-UT-10 (EPRI) - Generic Procedure for the Ultrasonic

Examination of Dissimilar Metal Welds

Supplement 11 — Qualification requirements for full structural overlaid wrought

austenitic piping welds

Generic procedure PDI-UT-08 (EPRI) - Generic Procedure for the Ultrasonic Examination of

Weld Overlaid Similar and Dissimilar Metal Welds

Code Case N-722 - Additional Examinations for PWR Pressure Retaining Welds in Class 1

Components Fabricated With Alloy 600/82/182 Materials Section XI, Division 1

MRP 139 - Material Reliability Program: Primary System Piping Butt Weld Inspection and

Evaluation Guideline



NRC and CNEN approved the use of the document:

• MRP-139 - Material Reliability Program: Primary System Piping Butt Weld Inspection and

Evaluation Guideline

According to MRP-139 - Locations in Westinghouse Design Plants



Part Examined ISI Angra 1 Total of welds in ISI Program

B5.10

Reactor Vessel

NPS 4 or Larger

Nozzle-to-Safe End Butt Welds

RCP inlet and outlet

nozzle. Loop 1 and 2

4 welds/2 for each loop

(Loop 1 – 14DM e 1DM)


Safety Injection 2 welds (24 DM e 21DM)

B5.40

Pressurizer

NPS 4 or Larger


Surge Line Nozzle 1 weld(*) (1DMW)

Spray Nozzle 1 weld (*) (43DMW)

Relief nozzle 1 welds (*) (1DMW)

Safety line 2 welds (*) (1DMW/12DMW)

B5.70

Steam Generator

B5.70 NPS 4 or Larger


INLET/outlet nozzle 4 welds/ 2 for each loop


(Loop 2 – 23DM e 24 DM)

ASME Sec XI IWA 2500-1

B-F – Pressure Retaining Dissimilar Metal Welds in Vessel Nozzles

(*) WOL

According the Angra 1 ISI program – procedure PI-V 12.

UT procedures – PDI-UT 10 for dissimilar weld and PDI-UT 08 for WOL.



ASME Sec XI IWA 2500-1

B-J - Pressure Retaining Welds in Piping

Part Examined ISI Angra 1 Total of welds in ISI Program

B9.10

B9.11

NPS 4 or larger

Circumferential welds

Safety Injection to

Reactor vessel

2 welds/ 1 for each loop (20 and 34)

During the 1P22 (2016), ETN had

identified these two dissimilar weld, that

since Preservice were inspected like not

dissimilar.

CNEN send a non conformance to ETN.

PDI-UT-2 (EPRI) - Generic Procedure for

the Ultrasonic Examination of Austenitic

Pipe Welds



During the outage (P22), ETN had performed some extra NDE in the welds 20 and 34:

- Visual

- Superficial

- Gammagraphy to compare with the Preservice X-ray.

- UT using the procedure EPRI PDI UT 2 (for not dissimilar weld) – that find the

discontinuity but it cant size it.

- Chemistry analysis

- CNEN had accepted these inspections, becase it was not find any descontinuity.

ETN consulted EPRI and WEC to find a solution for these two weld and it was informed

that “is a very unique” case of dissimilar weld.

EPRI doesnt have a PDI procedure to perform UT in this weld.

ETN, WEC and EPRI started the process to qualifify a PDI procedure to inspect them, so

EPRI has been building a mock up and developing a new EPRI PDI procedure.



• “...In fact, since 1994 until the end of 2006, a total of more than 300 nickel

base Alloy 182 or 82 welds in over 30 PWR plants, have been identified

with PWSCC after operating times between 53,400 and 180,000 EFPH

(Effective Full Power Hours)...” (EPRI/NRC)

Angra 1 (P17) 12.61 EFPY=110482 EFPH

Weld Overlay Material Volume

Weld overlay



• Weld overlay of PZR dissimilar weld

In 2009, ETN started the process to implemente the WOL in the PZR dissimilar weld.

The QA department sugested that the WOL should be done througt a relief request and a design change

package (DCP, according to 10 CFR 50.59 and ASME section XI IWA 4000), based on NRC TI 2515/172 –

Reactor coolant system dissimilar metal butt weld:

“ 03.03 Weld Overlays

Verify that the licensee has submitted a relief request and obtained NRC staff authorization to install the weld

overlays, whether full structural or optimized weld overlays.

c. 04.03 Weld Overlays.

ASME Section XI does not presently contain inspection requirements for weld overlays. Section XI has issued

Code Cases N-504-3, “Alternative Rules for Repair of Classes 1, 2, and 3 Austenitic Stainless Steel Piping”

and N-638-1, “Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper

Bead Technique.”

These two code cases are listed in Regulatory Guide (RG) 1.147, Revision 15, “Inservice Inspection Code

Case Acceptability, ASME Section XI, Division 1,” with limitations.

Although these code cases are approved with limitations in RG 1.147, their use for a weld overlay on an

Alloy 82/182 weld requires a relief request, since they were not written for this application.

ASME Section XI has issued N-740 and N-740-1, “Dissimilar Metal Weld Overlay for Repair of Class 1, 2, and

3 Items,” and is working on the second revision to this code case. When the NRC staff approves code case

N-740-X in RG 1.147 and endorses this regulatory guide in an update to 10 CFR 50.55a, application of

weld overlays will no longer require NRC approval through authorization of a relief request.”

During a meeting in CNEN, in 16/06/2009, all agree that ETN should send a relief request to CNEN and

start a design change package.



Preparing surface

Installing the equipment of WOL

Preparing the

Surface after

WOL

UT

Inspection

Welding operator



Residual Stress before and after WOL (spray nozzle):

After WOL - Residual stress in the Inner Surface of weld: -64 to -28 ksi

Before WOL - Residual stress in the Inner Surface of weld : 32 to 48 ksi



OLD Reactor Vessel Head

Angra 1 reactor vessel used to have penetrations for control rods and instrumentation

system, these penetrations were made of a nickel alloy (alloy 600).

In the case of vessel head with 8 <= EDY <= 12 (Effective Degradation Years for moderate

susceptibility), the case of Angra 1 before change, the requirements of EA-03-009 (*) and

Code case N-729-1(*) were:

• Every outage - visual inspection and

• Every two outage visual and volumetric inspection.

• This until the head is replaced, according to a

DCP (10 CFR 50.59 and ASME Sec XI – IWA 4000 (*))

(*) EA-03-009 - Issuance of order establishing interim inspection requirements for reactor

pressure vessel heads at pressurized water reactors)

Code case N-729-1 (Alternative Examination Requirements for PWR Reactor Vessel Upper

Heads With Nozzles Having Pressure-Retaining Partial-Penetration Welds Section XI,

Division 1)

10 CFR 50.59 - Changes, tests and experiments and

ASME section XI IWA 4000 – Repair/Replacement Activities



New Reactor Vessel Head

During the P18 (2013) ETN had changed the reactor vessel head.

(Design Change Package)

Vessel

Head

Steel Internal

coating

Rod Drive

Old ASTM A 533 gr B AISI304 Inconel 600

New ASTM 533 Gr B Cl 2 AISI 316 Inconel 690

Inspection according code case N-729-1.



Reactor Vessel Bottom

Every outage it is performed remote VT in the Reactor Vessel Bottom, according to

Code case N-722.



MSIP – Mechanical Stress Improvement Process

Plan (Future) - MSIP on the nozzle of reactor vessel



• CONCLUSION

Angra 1 has been following all applicable standards to the inspection

and mitigation of dissimilar welds.

The quality assurance department has been participating in activities

related to inspections and mitigations of dissimilar welds, according to

the requirements of CNEN NN 1.16 and 10CFR 50 App. B:

- Analyzing the normative base and procedures

- Checking the qualifications of personnel and equipment calibration

- Verifying the records and the design change package (WOL, vessel

head change)

- Qualifying the suppliers and

- conducting quality audits.



I would like to thanks

• The IAEA, CNEN and ETN

And

• My co-workers:

Emílio Lento

Jonas Lourenço

Magno V. Messias Jr

Marcelo da S. M. Ferreira

Millena de Souza Pereira

Paulo Roberto de Souza

Valéria Campos de Carvalho

Vera Lúcia Silveira da Cunha



REFERÊNCIAS

U.S. NRC

U.S.NUCLEAR REGULATORY COMISSION. Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing

Plants. Appendix B to Part 50

U.S.NUCLEAR REGULATORY COMISSION. Codes and Standards - 10 CFR 50.55a.

U.S.NUCLEAR REGULATORY COMISSION. Issuance of order establishing interim inspection requirements for reactor

pressure vessel heads at pressurized water reactors). EA-03-009

U.S.NUCLEAR REGULATORY COMISSION . Changes, tests and experiments. 10 CFR 50.59.

U.S.NUCLEAR REGULATORY COMISSION. Reactor coolant system dissimilar metal butt weld. TI 2515/172

U.S.NUCLEAR REGULATORY COMISSION. Review of Responses to NRC Bulletin 2003-02-Leakage from Reactor

Pressure Vessel Lower Head Penetrations and Reactor Coolant Pressure Boundary Integrity. NUREG 1863

EPRI

Generic procedure PDI-UT-10 (EPRI) - Generic Procedure for the Ultrasonic

Examination of Dissimilar Metal Welds

Generic procedure PDI-UT-08 (EPRI) - Generic Procedure for the Ultrasonic Examination of Weld Overlaid Similar and

Dissimilar Metal Welds

MRP 139 - Material Reliability Program: Primary System Piping Butt Weld Inspection and Evaluation Guideline

CNEN

COMISSÃO NACIONAL DE ENERGIA ATÔMICA, Inspeção em Serviço em Usinas Nucleoelétricas, Norma NE 1.25

COMISSÃO NACIONAL DE ENERGIA ATÔMICA, Licenciamento de Instalações Nucleares, Norma NE 1.04

COMISSÃO NACIONAL DE ENERGIA ATÔMICA, Garantia Da Qualidade Para a Segurança de Usinas Nucleoelétricas

e Outras Instalações, Norma NN 1.16.

ASME

RULES FOR INSERVICE INSPECTION OF NUCLEAR POWER PLANT COMPONENTS. ASME Boiler Pressure

Vessel. Seção XI. Edições : 1989, 1992, 1995, 1998, 2001 adendos até 2003.

Code case N-729-1 (Alternative Examination Requirements for PWR Reactor Vessel Upper Heads With Nozzles

Having Pressure-Retaining Partial-Penetration Welds Section XI, Division 1)

Case N-722 - Additional Examinations for PWR Pressure Retaining Welds in Class 1 Components Fabricated With

Alloy 600/82/182 Materials Section XI, Division 1



Thank you !

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