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ENT000650 - G. Gardner, Chair, EPRI Reactor Internals Working Group, Recent Materials Inspections of PWR Reactor Internals (Mar. 2015)
	ML15222A919
Person / Time
Site:	Indian Point
Issue date:	03/31/2015
From:	; Entergy Nuclear Operations
To:	; Atomic Safety and Licensing Board Panel
	SECY RAS
References
	RAS 28135, ASLBP 07-858-03-LR-BD01, 50-247-LR, 50-286-LR
	Download: ML15222A919 (10)
	v • d • e

ENT000650 Submitted: August 10, 2015 Recent Materials Inspections of PWR Reactor Internals Glenn Gardner, Dominion Chair, Reactor Internals Working Group NRC RIC Meeting March 2015

Topics Quick Overview of MRP-227-A Inspections Approach Reactor Internals Inspection Results to Date Observations 2

Basic Approach of Guidelines z Combine detection of aging effects with focus on safety function z Credit and coordinate with existing ASME Code inspections z Manage less active mechanisms by sampling, expand to additional scope based on results z Make the inspection consistent with component and its safety function 3

Basic Approach of Guidelines z Convey most requirements via simple tables z Ensure guideline is generally applicable to all PWRs z Needed and Mandatory requirements applicable to all US PWRs through NEI 03-08 initiative z Make the guideline a living document through reporting of results, review and update process z Engineering evaluation of relevant conditions guided by companion document, WCAP-17096, developed by PWROG 4

Development and Evolution of MRP-227 Early MRP-227 MRP-227 MRP-227 MRP-227 MRP-227 MRP-227-A Beginning Rev. 0 Rev. 0 SE Rev. 1 Rev. 1 SE Rev. 1-A

2003-2008

December,

November

December

Target Sept

Target July, 2008 2011 2011 2015 2017 Four major stakeholders influenced development under NEI 03-08

- Owners, NRC, EPRI, NSSS Vendors Extensive interaction among stakeholders during development Implementation began in 2009 and continues each outage season Results to date show no unexpected issues MRP-227 continues as a living document 5

B&W MRP-227-A RV Internals Primary Scope Lower Core Barrel Bolts (UT)

Baffle-to-Former Bolts (UT)

Flow Distributor Bolts (UT)

Plenum Cover Weldment Rib Pads Support Flange and Core Support Shield Top Flange (VT3)

Core Support Shield Vent Valve Top & Bottom Retaining Rings (VT-3)

Upper Core Barrel Bolt Locking Devices/Welds (VT-3)

Lower Core Barrel Bolt Locking Devices/Welds (VT-3)

Baffle Plates (VT-3)

Baffle-to-Former Bolt Locking Devices/Welds (VT-3)

Internal Baffle-to-Baffle Bolt Locking Devices/Welds (VT-3)

Flow Distributor Bolt Locking Devices (VT-3)

Alloy X-750 Dowel-to-Guide Block Welds (VT-3)

Incore Monitoring Guide Tube Spiders & Lower Grid Rib Welds (VT-3)

Control Rod Guide Tube Spacer Castings and Cap Screws (VT-3) 6

CE MRP-227-A RV Internals Primary Scope Core Shroud Bolts (Bolted Design) (UT)

Core Shroud Plate-Former Plate (Welded Design) (EVT-1)

Welded Shroud Plates (Full Height Design) (EVT-1)

Core Shroud Assembly [Bolted (VT-3); Welded (VT-1)]

Core Barrel Upper Flange Weld (EVT-1)

Core Barrel Lower Cylinder Girth Welds (EVT-1)

Core Support Column Welds (VT-3)

Core Barrel Lower Flange (TLAA or EVT-1)

Core Support Plate (TLAA or EVT-1)

Fuel Alignment Plate (Full Height Design) (TLAA or EVT-1)

Instrument Guide Tubes (in CEA Shroud Design) (VT-3)

Lower Structure Beams (Full Height Design) (EVT-1) 7

Westinghouse MR-227-A Primary Scope Control Rod Guide Card wear inspections (VT-3)

Lower Control Rod Guide Tube (CRGT) Lower Flange welds (EVT-1)

Baffle Former Bolts (UT)

Baffle Former Assembly (including seams) (VT-3)

Baffle Former Edge Bolts (VT-3)

Upper Core Barrel Flange to Shell Weld (EVT-1)

Lower Core Barrel Flange Weld (EVT-1)

Thermal Shield Flexures (VT-3)

Core Barrel Cylinder Girth Welds (EVT-1)

Internals Hold-Down Spring (if applicable material type)

(measurement) 8

Examples of Inspected Components 9

W Lower CRGT Flange Welds 10

Thermal Shield Flexures (VT-3) 11

VT-3/Measurement W Control Rod Guide Cards Acceptable Observed Wear 12

VT-3 of B&W Control Rod Guide Tube (CRGT) Spacer Castings and Cap Screws 13

Baffle-Former Assembly Bolts External Hex Internal Hex 14

B&W Lower Barrel and Flow Distributor Bolts 15

Core Barrel Welds Neutron Panel and lower girth weld 16

Inspection Implementation 17

Inspection Implementation

- Some inspections best performed with core barrel in vessel

- Others require core barrel removal

- Common to split inspections over two or more outages

- Typically integrated with ASME Section XI exams

- Special tooling often required

- Vendor crew of roughly 20 specialists required 24/7

- Vendor crew typically experienced on both PWRs and BWRs

- Owner oversight 18

Inspection Results 19

Inspections by Plant Design - as of Fall 2014 Design Initial Ops Bfl Blts CB Bolts CRGT Spc BMI Spdr BW 1973 2012F 2012F 2012F 2012F BW 1973 2013S 2013S 2013S 2013S BW 1974 2014S 2014S 2014S 2014S 3 of 6 total Bfl Blts CRGT WldsCB Wlds Gd Cards LCS CE 1971 2014S 2014S 2014S 2014S 1 of 12 total Bfl Blts CRGT WldsCB Wlds Gd Cards W2 1969 2011S 2011S 2011S 2011S W2 1970 2013S 2013S 2013S 2013S W2 1973 2014S 2014S 2014S W2 1974 2014F 2014F W2 1974 2013F W3 1970 2013F 2013F 2012S W3 1972 2010F 2012S 2013F 2012S W3 1972 2014S W3 1973 2011S 2012S 2014S 2012S W3 1973 2014F 11 of 48 total 20

Results to Date Initial full inspections at W and B&W and partial CE NSSS designs have not identified any major issues of concern Current results reduce uncertainty in mechanism activity Issues of greatest concern not seen

- SCC of austenitic welded components not observed Cracking currently limited to high strength bolting

- IASCC of welds not observed, indications limited to bolts

- Macroscopic effect of void swelling not observed 21

By the Numbers*

15 units begun or completed MRP inspections 959 W guide tube flange welds inspected 2427 inches of irradiated welds inspected (approx.)

9125 inches of non-irradiated welds inspected (approx.)

2226 CASS items inspected 8887 baffle bolts UT inspected**

1654 B&W high strength bolts UT inspected**

108 B&W baffle plates inspected

All numbers approximate. Includes reported inspections through Fall 2014; some data includes retired plant; additional data may affect results slightly

- Includes retired unit 22

By the Numbers*

Zero Guide Tube Flange weld indications Zero irradiated girth weld indications One non-irradiated weld indication One CASS VT-3 indication 136 baffle bolt indications (1.5% of total) 20 B&W high strength bolt indications (1.2% of total)

All numbers approximate. Includes reported inspections through Fall 2014 ;

additional data may affect results slightly 23

Trends and Observations Almost no observed austenitic SS stress corrosion cracking (one indication reported)

Irradiation Assisted SCC is extremely limited

- Currently limited to bolts

- Explained in part by irradiation stress relaxation

- High barrier to initiation in PWR environment

- Compared to other plant designs, major benefit from coolant chemistry 24

Trends and Observations No macroscopic effects of void swelling

- No distortions, cracking, or excessive bolting failure High-strength nickel alloy clevis insert bolting failures

- However, not in safety function load path Guide card wear will require monitoring

- MRP Interim guidance MRP-2014-006 issued 25

Trends and Observations Sampling approach to inspections very successful

- Spectrum of plant designs, materials, heats

- Transition to more focused sampling for guide cards Efficiency could be increased, and is being pursued Integrated fleet management strategies are possible 26

MRP-227-A Experience Summary Exam results show few instances of service-induced degradation flaws, as expected Overall uncertainty in aging mechanism activity reduced Implementation by owners is thorough, but exams are difficult, as well as resource and dose intensive Some adjustments and efficiencies are needed, as expected with a living program Lessons learned incorporated into MRP-227 Rev. 1 27

TogetherShaping the Future of Electricity 28

ML15222A919

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