Laser Direct Manufacturing of Nuclear Power Components

Dr. Jyotsna Iyer, Dr. Scott Anderson, Gautham Ramachandran, Georgina Baca, Scott Heise, Dr. Slade Gardner

3 November 2014

Acknowledgment: “This material is based upon work supported by the Department of Energy , Office of Nuclear Energy, Idaho Operations, under Award Number DE-NE0000542”

Disclaimer: “This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.”

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Nuclear Energy in the U.S.

• 104 reactors in the U.S. providing 20% of our electricity – 4 new plants under construction in U.S., >60

globally, >150 on order• Current Light Water Reactors (LWR) cost $10B-

$12B/unit– Costly on-site construction

• Next generation Small Modular Reactors (SMR) estimated $800M-$2B/unit– DOE SMR program funding ~$400M– B&W and NuScale selected for concept development – Factory fabrication, rapid installation

• Advanced materials and manufacturing are significant industry drivers

100

200

300

2010 2020 2030 2040

Gigawatt s- electr ic

Current reactors, 40 years Current reactors, 60 years

New capacity being considered 4 Builds per year starting 2021

Generating capacity with 80-year life

02050

Advanced/Affordable Manufacturing methods are key enablers for competing in $700B global market

DOE Nuclear Energy Enabling Technologies (NEET) Advanced Manufacturing Methods (AMM)

Contract: DE-NE0000542POP: 36 months, GFY13 - GFY15

DOE Team: Alison Hahn (HQ), Jack Lance (HQ), Bradley Heath (HQ)LM Team: Gautham Ramachandran, Dr. Scott Anderson, Dr. Jyotsna Iyer, Georgina Baca, Scott Heise, Dr. Slade GardnerDr. Eric Faierson, Quad City Manufacturing Laboratory

Scope HIGHLIGHTS

Purpose: Position U.S. to compete in $B international market for nuclear power via enabling technology that significantly reduces development and operational costs and manufacturing lead time for nuclear reactors

Project Objectives: Demonstrate >50% cost and schedule reduction using additive manufacturing methods. Develop, advanced radiation tolerant alloys via nanophase modification during additive manufacturing for reduced life cycle costs.

Technical Approach• Build manufacturing demonstrations of complex

parts demonstrating design flexibility and shortened design-to-manufacturing cycles

• Employ nanophase alloy modification via Laser Direct Manufacturing (LDM) to create enhanced radiation tolerance in the components

• Demonstrate the cost and schedule benefits through case studies and business case analyses

(Unsintered powder)

Laser Melting

Sintered powder

Completed Layer

Net-Shape Manufacturing Demo Articles built in <18 hours, no assembly/joining required – Fuel rod spacer grids manufactured using 316L SS and Inconel600

LM CE&T Energy IPT funding cost-share and supporting industry engagement and growth opportunities

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Background for Alternate Nuclear Materials Selection

N13137-01

Generations II-IIISodium Fast Reactor

Molten Salt Reactor

Gas Fast Reactor

Lead fast Reactor

Superficial-Water-Cooled Reactor

Very High Temperature Reactor

1400

Tem

per

atu

re (

°C)

1200

100

800

600

400

200

0

0 50 100 150 200

Displacements Per Atom (dpa)

N13137-02

Fuel RodCutaway

FuelPellets

Fuel Assembly

UO2

MOX

Clad

Fuelpellet

Fuelrod

Spacergrid

Water flow

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Table of Comparison Criteria for Selection of Alternative Nuclear Materials

Comparison criteria • Low neutron absorption• Elevated temperature mechanical

properties– Creep resistance– Long-term stability– Compatibility with reactor

coolant• Resistance to irradiation-induced

damage (greater than 200 dpa)–Radiation hardening and

embrittlement–Void swelling–Creep–Helium-induced embrittlement–Phase instabilities

Alternate Nuclear Materials• BASELINE: Traditional ferritic/martensitic

steels (HT-9) or later generations of F/M steels

• OPTION 1: ODS steels to examine effect of direct manufacturing methods on nanoscale oxide domains

• OPTION 2: Inconel 800 series of materials to study the effect of processing parameters offered by direct manufacturing methods to improve performance under irradiation

• OPTION 3: Among the refractory alloys, the Mo (TZM) alloys. These have a high operating temperature window and also, the most information on irradiated material properties

Based on customer feedback at Technical review, materials down-selected to 316SS, ODS steels and Inconel alloys

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Material Down selection for DM Demonstration

Emerging literature in Austenitic ODS alloys• Development of Austenitic ODS Strengthened Alloys for Very High Temperature Applications

(http://energy.gov/sites/prod/files/2013/09/f2/Stubbins_Austenitic%20ODS%20NEUP.pdf)• Synthesis and Characterization of Austenitic ODS alloys (http://www.mme.iitm.ac.in/murty/?q=node/96)

• Alloys: Inconel 600, Inconel 718, Incoloy 800, 316L SS, ODS Steels• Oxides: Yttrium, Cerium - Mix of nano- & micron- sized oxide particles

selected for mixing

10 x 10 Grid 10 x 10 Grid 3 x 3 Grid

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Process Parameter Variation During Part Fabrication – Inconel 600

Specimen size Scan speed Laser powerInconel 600 1cmX2cmX1cm 1100mm/s 195W Standard EOSInconle 718 1cmX2cmX1cm 1200mm/s 195W Standard EOS

1cmX2cmX1cm 1000mm/s 195W 180W 165W 150W1cmX2cmX1cm 900mm/s 195W 180W 165W 150W1cmX2cmX1cm 800mm/s 195W 180W 165W 150W1cmX2cmX1cm 1200mm/s 195W 180W 165W 150W1cmX2cmX1cm 1400mm/s 195W 180W 165W 150W

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Process Parameter Effect on Fabricated Part Density – Inconel 600

Laser power of 195W makes the fabricated article almost insensitive to scan speed

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Process Parameter Effect on Fabricated Part Density – Inconel 718

Laser power of 165W most consistent for Inconel 718; more scatter in density data

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Microstructure Characterization

QCML manufactured 56 of Inconel 600 samples

Fourteen were selected Five samples were selected for

microstructure characterization Sample #12 was selected for mounting

in both the x-y & z directions for a total of six samples

Metallography Procedure Mount/ grind/ polish Micrograph (photographs) Scanning Electron Microscopy

(SEM) Etch Micrograph SEM

Notes:Power (W) Speed (mm/s)

4 600_150_1400 8.235 150 1400

10 600_180_1400 8.299 180 1400

11 600_195_800 8.384 195 800

12 (a) 600_195_1100 8.37 195 1100Sample #12 was selected to be mounted in both the x-y & Z planes (long)

12 (b) 600_195_1100 8.37 195 1100Sample #12 was selected to be mounted in both the x-y & Z planes (trans)

14 600_195_1400 8.346 195 1400

Proces ParametersSample # Sample name Micrograph (100X) Density (g/cm3)

Samples produced at the higherspeed rate and lower power demonstrate more voiding based micrographs

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• BSE imaging revealed the solidification/grain microstructure• Microstructure appeared similar in the three locations examined• No titanium nitride particles were detected (titanium nitride particles are typically

found in wrought material)• Black areas in images are voids

Bottom

Middle

Top

Backscattered Electron Imaging of Sample 600-195-1400

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• Mount/ grind/ polish• Micrograph

(photographs)• Scanning Electron

Microscopy (SEM)• Etch• Micrograph • SEM

Microstructure Comparison of Inconel 600 Bar Stock Sample vs Additive Manufactured Sample

Inconel 600: Bar Stock Sample 500X BSE 10kV not etched

Inconel 600: Sample 500X BSE 10kV not etched

Noticeable Grain Structure differences due to manufacturing process

• QCML manufactured 56 of Inconel 600 samples• Fourteen were selected • Five samples were selected for microstructure characterization

Metallography procedure

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Examination of Microstructure of Edge Transition

(c) Top Edge Transition: 500X

Top Edge: Terminating Side

Terminating Side

Initiating Side

Side

Side

(d) Away from edge: 500X

(b) Top Edge:500X

a) Inconel 600 Micrographs show (b) top edge (c) transitions (d) interior of sample at 500X

(a)

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Test Coupons Ready for Mechanical Testing

Inconel 600 longitudinal, transverse, and 45deg specimen blanks after LDM

Samples heat treated (900C for 1-2hr) to remove after fabrication to prevent warping

• This build layout produces 45 test coupons in a single build at 1100mm/s and 195W

• The test coupons are cylinders with 0.5" diameter by 3" length. 

• 15 cylinders are in horizontal orientation

• 15 cylinders are in vertical orientation

• 15 cylinders are at 45 degrees with respect to the horizontal.

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Next Steps

• Mechanical & microstructural characterization of test coupons for Alloy 600

• Test specimen build for Alloy 718, Alloy 800• Characterization of Alloy 718 & Alloy 800 test specimens• Test coupon build for Alloy 718 & Alloy 800• Mechanical & microstructural characterization of test

coupons for Alloy 718 & Alloy 800• ODS steel mechanical blending & trial runs

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Back up slides

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Metallurgy of AM Technologies• Weldable alloys are readily manufactured via AM

– Titanium alloys, stainless steels, alloy/tool steels, nickel-based alloys (Inconel), cobalt-based alloys

• Enables unique control of microstructure– Very fine grain sizes due to high solidification rates– Can produce microstructures not possible using conventional

manufacturing methods

• Equivalent or superior mechanical properties to wrought alloys

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Material Down Selection for DM Demonstration

Alloy Procurement StatusInconel 600 250lbs in-houseInconel 690

Inconel 718 250lbs in-houseInconel 625

Incoloy 800Purchased from Carpenter - expected ship date 9/17

Incoloy 800H

316 SS316Ti SS

316L SS In-house

304 SSCorrect particle size not available

ODS Steels

Oxide list downselected - further details being worked out

T91

• Mix of nano- and micron- sized oxide particles selected for mixing with 316SS

Emerging literature in Austenitic ODS alloys• Development of Austenitic ODS Strengthened

Alloys for Very High Temperature Applications (http://energy.gov/sites/prod/files/2013/09/f2/Stubbins_Austenitic%20ODS%20NEUP.pdf)

• Synthesis and Characterization of Austenitic ODS alloys (http://www.mme.iitm.ac.in/murty/?q=node/96)

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Literature Notes for Austenitic ODS Steel Composition

• (http://energy.gov/sites/prod/files/2013/09/f2/Stubbins_Austenitic%20ODS%20NEUP.pdf)

SPACE SYSTEMS COMPANYPreliminary Examination of 600-195-1400; Mt 14.046

8-7-14 JAB STAR Labs 20

• Several Inconel 600 samples were metallographically cross-sectioned and polished• Examination of microstructure on sample 600-195-1400 was conducted using

backscattered electron imaging (BSE) Sample was not yet etched BSE images were taken in the three locations shown below

~ 1cm

Top

Mid

Bot

Optical Image of Polished Cross-SectionSample 600-195-1400

Mt 14.046