U.S. DEPARTMENT OF ENERGY Nuclear Energy
Transcript of U.S. DEPARTMENT OF ENERGY Nuclear Energy
U.S. DEPARTMENT OF
ENERGY Nuclear Energy
National Aeronautics and Space Administration
ADVANCED STIRLING RADIOISOTOPE GENERATOR INTEGRATED FEDERAL PROJECT
Advanced Stirling Radioisotope Generator: Teamwork and System Reliability
Chris Steffen, Jr.
1-May-2013
Government & Contractor Partnership
Advanced Stirling Radioisotope Generator (ASRG)
AC Power DC Power from ASCs Connector ~--~t.~~ 7li::;;.,~,..,......_~
to SV
ASC Controller
Unit (ACU)
Fins Advanced Stirling
Convertor (ASC) (2)
3
Cold-Side Adapter Flange
(CSAF) (2)
Shunt Dissipater
Unit (SOU)
GPHS (2)
ASRG Project Key Deliverables
Qualification Test Unit
Fueled & Tested 2016
Flight #1 Unit
shipped for Fueling
& Testing 2016
Flight #2 Unit
shipped for Fueling
& Testing 2017
ASRG Mass Metric- March 2013
45
40 RPS PO Reserve
--;:o 35 .::t:. -
--,. - I
Jan-08 Jan-09 Jan-10 Jan-11 Ja n-12 Jan-13 Jan-14 Jan-15
5
150 -
145
-! 140
\.,.
<1> ~ 0
Q,.
E 135 Q) ... ~
> V'l
G) ... ~ 130 a. E 0 u
~ 125 V) <{
120
115
ASRG Power Metric- March 2013
CBE Power
••••••••••• Output Power Req (Original) = 140 W • •••• ••••••••••••• •
•••••• •
New Monte Carlo Estimate: Cumulative Probab ility of Achieving 130.0 W = 99%
CBE Power = 140.8 W
Cont ingency
Predrcted Power (Worst Case) .... ••••••••
Worst Case Power loss I ~'Total Power Margin = 3.99%
Predicted Power(RSS) = 10.00~ ..~~T~T~T~~~~=~l735~.~47\~~~~-~J' ..
LM Margin = 4.15% •••••• Output Power Req (Updated) = 130 W : ... ..,.*-
,,.
RPS PO Reserve = 1. 56% t '~ RPS PO Power Commitment = 128 W
Jan-os Jan-09 Jan -10 Jan-11 Jan-13 Jan -14 Jan-15
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ASRG Reliability Metric- March 2013
Heate r Head
Spring
Transit ion & Feedt hru
ASC Common
Cause
Gas Bearings
ASRG System
Probability of
Failure (POF)
3.1%
Other POF
0.06%
ACU Common
Cards#l & #2
ASRG System Probability of Success
(Delivered power for 17 years) 96.9%
Card #1 (Primary)
5.4%
Output current sense & voltage
.monitor
control monitor
card lt3 (Alternate) PDF
5.4%
Questions about this graphic, Chr is Steffen (stelfen@nasa gav)
• Reliability challenge: heater head casting
• Thin-walled metallic Heater Head component (outlined in yellow)
• Ni-based super alloy Heater Head machined from casting
• Casting is known for potential oxide inclusions (ceramic flakes)
• Micro-focused Computed Tomography (CT) key to "seeing" these flaws
• Component yield was developing as an issue; parts could meet criteria
• NASA Engineering Safety Center: "criteria needs test-verified basis"
Potential orientations for oxide inclusion
Hot End (850° C)
Stirling Engine
Cold End (90° C)
Linear Alternator
ArJV;:)fJl~ArJ Stirlinn ConvArtor
(/')
u 0.. c.o rl
(/')
u 0.. 0 N
Plan: Heater Head development 1st znd
Pair Pair
ASC-Engineering Units _____ _ Need: 50% yield
Jrd
Pair
• Qual Pair MIP
• • znd Jrd
Pair Pair MIP MIP
4th
Pair
• 4th
Pair MIP
Apr-11 May-11 Jun-11 Jul-1 1 Aug-11 Sep-1 1 Oct-11 Nov-11 Dec-11 Jan-12 Feb-12 Mar-12 Apr-1 2 Moy-12 Jun-12 Jul-12 Aug-12 Sep-12 Oct-12 Nov-12 Dec-1:
Mar-11 ASC-E3 Deliveries
10 ASC-Q S-F Deliveries
• Reality: Heater Head development
ASC- Engineerin 44% yield
1st 2nd
Pair Pair Jrd
Pair
Mitigation: 5 more @ 6 months
... Qual Pair MIP
ASC-E3s: Need 4 more
Spares: Have 6 more
ASC-Fs: Need 7 more
. I
... ... 2nd 3rd
Pair Pair MIP MIP
4fh
Pair
... 4th
Pair MIP
Apr-11 May-11 Jun-11 Jul-11 Aug-11 Sep-11 Oct-11 Nov-1 1 Dec-11 Jan-12 Feb-12 Mar-12 Apr-12 May-12 Jun-12 Jul-12 Aug-12 Sep-12 Ocl-12 Nov-12 Dec-1:
Mar- 11
. 11 ASC-E3 Deliveries
ASC- Q 6- F Deliveries
Reliability challenge: heater head casting
Technical Risk: Oxide Inclusions present a risk to meeting fatigue life requirement (68 years)
Schedule Consequence: Insufficient component yield threatens critical path schedule with 3 months
Approach: Assemble investigation team and resolve in 3 months
1. Verification: Material coupon testing -+ batch specific matl props
2. Verification: Fracture mechanics & selection criteria -+ test-verified properties
3. Validation: Component stress testing -+ design specific reliability data
Goal: Resulting in test verified, design specific acceptance criteria for 4x design life on fatigue, validated with component testing
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Skills and Assets Required
FEM Analysis
Rapid design & manufacturing
ally
Micro-focused CT scanning
Material Properties testing & Fracture Mechanics analysis
•
Structural Dynamics Testing & cumulative damage analysis
SEM Imagery
• Key Results
1. .Comprehensive approach: Sixteen* separate fatigue crack growth specimen tests Design trade study on "critical-flaw-size vs wall thickness" Refined (tighter!) acceptance criteria, supported by test-verified material.s properties
Eight qualification level vibe stress tests on five different components
2. NESC concurrence: results conclusions
residual risk for the ASRG project
3. · Timely closure: preserved system reliability and margin for fatigue life Preserved project schedule despite tighter acceptance criteria
Only possible with a badge-less team working pulling together
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Thanks to the investigation team
• Greg McNelis- LM (co-lead)
• Dennis Petrakis- LM
• Glen Davis- Sun power
• Kyle Wilson - Sun power
• Lou Qual Is- ORNL
• Louis Ghosn - NASA GRC
• Wayne Wong - NASA GRC
• Kate McGinnis- NASA GRC
• Jeff Schreiber- Consultant, formerly GRC
• Brad Kirkwood, INL
• Jack Chan - LM
• Scott Benson, GRC -- Project Management Rep.
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• Randy Bowman - GRC
• Ramesh Kalluri - GRC
• Dave Krause - GRC
• Jack Telesman -GRC
• Chuang Ha - LM
• Ron McNally - LM
• Gary Wood - Sun power
• Aaron Thomas- Sun power
• Kim Otten - GRC
• Sal Oriti - GRC
• Zach Williams - GRC
Consultants (NESC):
Dawn Emerson, Bob Piascik, Bill Prosser, Raju lvatury, Dave Dawicke