radioisotope*thermoelectric*generators** based*on* am · pdf fileice*&*gas*giants* •...
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Radioisotope Thermoelectric Generators Based on 241Am
Imag
e of
Ura
nus
Cou
rtesy
of N
AS
A Im
age of Mars G
ale Crater
Courtesy of N
AS
A JPL/C
altech
Richard Ambrosi ([email protected]), Hugo Williams, Emily Jane Watkinson et al. University of Leicester, Department of Physics & Astronomy & Department of Engineering
Marie-‐Claire Perkinson, Kevin Tomkins Airbus Defence and Space, Stevenage
Stephen Gibson Lockheed Mar@n, Ampthill
Tim Tinsley, Mark Sarsfield Na@onal Nuclear Laboratory, Sellafield
Mike Reece, Kan Chen Queen Mary University of London
Kevin Simpson, Mark Robbins European Thermodynamics Ltd, Leicester
Keith Stephenson European Space Agency
Commercial in Confidence
• Radioisotope power sources are an important technology for future European space exploraRon missions resulRng in: - More capable spacecraT. - Probes that can access distant, cold, dark and inhospitable environments. - Probes that can operate more effecRvely close to the Sun. - Missions using nuclear power can provide higher science return given the extended
operaRonal lifeRmes. - In many cases nuclear systems can enable missions that are very challenging.
• Focus is on 241Am for the radiogenic heat source.
• Programme is based on incremental technology readiness level upliT to increase the maturity of systems – this strategy will: - Provide greater freedom for science communiRes in Europe to propose missions that
include radioisotope power sources. - Facilitate the inclusion of technology soluRons in mission studies by industry and
agencies. - Deal with technology challenges in a systemaRc and efficient way.
IntroducRon
Commercial in Confidence
• The European programme targeRng mulRple strands:
- Isotope producRon.
- Isotope containment (cladding and aeroshell).
- Heat source development (different geometries and aeroshell material trades).
- Radioisotope thermoelectric generator (RTG) design and development.
» Thermoelectric materials and modules.
- SRrling generator design and development.
- Radioisotope heater unit design and development.
Radioisotope Power Systems: ESA Funded AcRviRes
Commercial in Confidence
RTG
Imag
e of
MM
RTG
and
GP
HS
Mod
ule
Cou
rtesy
of N
AS
A, U
S D
OE
9.95 x 9.32 x 5.31 cm3
Images of MMRTG and content courtesy of US DOE & NASA
Ice & Gas Giants
• Increasing interest in tackling the exploration challenges of the outer solar system.
• New architectures and innovative mission design.
• Small platforms could play a role in a multi-spacecraft mission concept.
- Main orbiting spacecraft, small deployable spacecraft, probe.
• Radioisotope power and heat in different scalable formats could have an important role to play.
Images cou
rtesy of NAS
A
Pioneer
New Horizons
Moon & Mars
Surviving in Extremely Cold Environments on the Moon
Network Mission
Image of INSPIRE Network Mission Courtesy of ESA. Images of the Lunar South Pole from LRO Courtesy of NASA & UCLA. Images of Viking, Spirit, Opportunity and Curiosity Courtesy of NASA, JPL.
Spirit & Opportunity
Curiosity
Viking
Commercial in Confidence
2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
ESA Funded Radioisotope Power Programme
Isotope Selection Isotope Production
(Phase 1) Isotope Production (Phase 2)
RTG(TRL3) RTG
(TRL4)
RHU(TRL3)
Commercial in Confidence
Fuel ProducRon
• 120 tons of separated reprocessed Pu. • Approximately 2-‐3 tons of Am-‐241.
• Full scale producRon of Am ~10-‐20 kg / year.
Imag
e C
ourte
sy o
f ES
A &
Nat
iona
l Nuc
lear
Lab
orat
ory
Commercial in Confidence
• RTG requirement is to develop scalable power output and modular heat source designs for iniRally for 5 We -‐ 50 We and later from 10 We to 50 We RTG systems.
- IteraRve flight design programme.
• IdenRfy suitable thermoelectric materials and build test modules. -‐ UK team focused on bismuth telluride. -‐ Incremental improvements in materials and manufacturing methods. -‐ Independent commercial producRon capability.
• Electrically heated laboratory prototype system -‐ GeneraRon 1: -‐ Target power of 80 W thermal and 4 W electric i.e. 5% system efficiency. -‐ RTG prototype to TRL 3. -‐ Develop a test bed for thermoelectric generators as part of an RTG system.
RTG Development in the UK
Commercial in Confidence
RTG Development in the UK
Gen 1 -Flight System Design
Gen 2 – Flight System Design
Gen 1 – Lab Prototype System
(TRL3)
Manufactured modules (40 x 40 mm2 161 couples)
• Industrial thermoelectric generator manufacturing methods with incremental improvements to well-‐characterised materials.
• Establishing full producRon capability in the UK.
• Bespoke unicouple design.
Commercial in Confidence
System Efficiency & Specific Power
2"
3"
4"
5"
2" 2.5" 3" 3.5" 4" 4.5" 5"
Mod
elled&Po
wer&Outpu
t&(W
e)&
Experimental&Power&Output&(We)&
6"mm,"Ti"heatshield" 6"mm"+"Au"heat"shield" 6"mm"BST,"Au"heat"shield"
8"mm,"Ti"heatshield" 8"mm,"Au"heatshield" 6"mm"BST"+"B4C,"Au"heat"shield"
+5%"+10%"+15%"
=5%"=10%"=15%"
ηRTG = 5.0% "
ηRTG = 4.5% "
ηRTG = 4.0% "
ηRTG = 3.5% "
ηRTG = 3.0% "
Commercial in Confidence
Summary • The current ESA space nuclear power programme is aimed at addressing key technology
components.
- RTG programme has focused on iteraRve approach to developing a flight design, producing a laboratory prototype and mulRple generaRons of bismuth telluride thermoelectric generators.
- Since the programme kicked off in 2008, a lot has been achieved at a rapid rate of development.
- Cost effecRve projects involving mulRdisciplinary teams and a structured collaboraRon between academia and industry.
- Knowledge base on radioisotope systems has been increased significantly, posiRoning the Europe as an intelligent user of the technology to support future European uRlisaRon of radioisotope systems.
- Future will focus on radioisotope heater units and advancing the RTG flight design and working prototype to TRL 4, targeRng 10 W electric output from 200 W thermal power output.
Acknowledgements Sue Horne, Major Chahal, Nick Cox UK Space Agency, Swindon, Wiltshire, UK