Democritos a Europe funded project preparing demonstrators

for high power nuclear electric space propulsion

Mr. Frédéric Masson, Mr. Jean-Marc Ruault 1 Dr. Jean-Claude Worms, Dr. Emmanouil Detsis 2 Mr. André Beaurain, Mr. Francois Lassoudiere 3

Dr. Enrico Gaia, Mrs Maria Cristina Tosi 4 Dr. Frank Jansen, Mr. Waldemar Bauer 5

Dr. Alexander Semenkin 6 Mr. Tim Tinsley, Mrs Zara Hodgson 7

frederic.masson@cnes.fr

1. MEGAHIT Outcomes of the project

Democritos is the follow-up of Megahit.

Conclusions of Megahit led to propose the Democritos project.

Megawatt Highly Efficient Technologies for Space Power and Propulsion Systems for Long-duration Exploration Missions

REACTOR

RADIATORS

RADIATORS

POWER CONVERSION

MANAGT & DISTRIBUTION

ELECTRIC THRUSTERS

PROPELLANT

Power processing

UNIT

Power processing

UNITPAYLOAD

SH

IELD

System studied - principle & performance targets

Target = High power (1 Mwe) nuclear electric propulsion Fission reactor provides heat power. Power conversion module converts it to electrical power. Electrical power feeds electrical thrusters. Hypothesis = Departure from a a sufficiently high orbit (800km or more) System can function 5 years in full power on a total lifetime of 10 years Spacecraft composed of at least 2 modules assembled in orbit: the transport power module with NPPS target: < 20 t (20 kg/kW) and the module with payload+propellant Electric propulsion system specific impulse range ~ 3000…8000 seconds

Reference missions - 2 for 1MWe 20t vehicle

• NEO deflection deflection by acting as a gravity tractor. could deflect Apophis trajectory by 1 million kilometer. If spacecraft leaves Earth in 2021, would reach Apophis in 200days and deflect it by staying a distance of 300m during 40 days.

• Outer solar system missions – for Europe (Jovian moon) orbit: 3 to 10t of payload in ~3 years (Isp=7000sec). A

chemical stage, without gravity assist manoeuver, would put only 300kg of payload in this orbit.

– For Titan 3 to 12 t of payload in Titan orbit in 3.5 to 6 years (Isp 6000s to 9000s).

• Lunar orbit tug With a launcher capable of launching 80t in a 800km orbit 2 times per year, 650t of payload can be brought in lunar orbit in 10 years.

• Cargo support mission for manned Mars mission

Can bring 15t in 400 days (Isp=6000sec) Mission analysis performed by Keldysh Research Center

Thermodynamic maps + mass budget (near future)

System Brayton Direct 1300K

reactor 4,0t Shield (20° cone angle, 1012n/cm² at 40m behind, elliptical shape ratio of 0.5)

1,7t Conversion (compressor, turbine, alternator, recuperator) 2,5t Radiator mass (including radiator heat exchanger) 5,8t Radiator surface (both sides radiate) 550 m² (1100m²)

Structures & circuits (20%) 2,8t total mass 16,8 t Rough specific mass (no PMAD or EP) 17kg/kW

Brayton direct 1300K

Objective of 20 kg/kW can be achieved

Brayton indirect 1600K, order of magnitude

System Brayton Indirect 1600K

reactor 0,9t Shield (20° cone angle, 1012n/cm² at 28m behind, elliptical shape ratio of 0.5) 1,0t Primary exchanger 1,0t Conversion (compressor, turbine, alternator, recuperator) 1,9t

Radiator mass (including radiator heat exchanger) 3,0t Radiator surface (both sides radiate) 270m² (540m²) Structures & circuits (20%) 1,7t total mass 9,4 t Rough secific mass (no PMAD or EP) 9kg/kW

Thermodynamic maps + mass budget (far future)

With advanced technologies, possibility to decrease the mass of the power system by 2

High Level concept and reference vision • Definition of general architecture and thermodynamic maps. • List of technologies for main sub-systems • For most of subsystems: a high TRL reference, a lower TRL / higher performance

alternative Technology plans & System Roadmaps Roadmaps include: • Lists of promising solutions with trade-off to perform • identification of technological gaps and maturation needed. • Preliminary planning, including technology maturations, ground demonstrators (2022),

space tests platform, and a first spacecraft utilization in 2032. Workshop (Brussels, december 2013) ~ 90 participants. Stakeholders from EU, US, Russia, China, Brazil and South Africa Consolidation of technological choices & roadmaps. Positive feedback from stakeholders, with frequent interest in joining.

Project results

Some Outcomes from the Megahit workshop Some choices still need consolidated consideration

• Nuclear fuel (trade-off considering performance, safety, availability, non-proliferation)

• Electric thrusters (type and number of thrusters)

• Direct/ Indirect cycle

To demonstrate the safety of the reactor, even in case of launch failure,

The need to assemble many parts in orbit may require advances in robotics.

Maturations/ new development needed, especially for components compatible with high temperature/ long duration:

• nuclear reactor (fuels, mechanical commands, absorbers, reflectors)

• the turbine blade and disk,

• conversion bearings,

• heat exchanger between primary and secondary circuit (if a heat exchanger is required).

Need of lower power demonstrators, as part of technologies maturation, and demonstration of correct functioning of the system (for instance, a strategy for transient phases should also be defined, allowing coherent functionning between core, turbine, radiator and thrusters).

Proposition of Democritos project

2. DEMOCRITOS: A presentation of the project

DEMOnstrators for Core, Conversion, Radiator, and Innovative Thrusters for Orbiter deflection and Space exploration

Democritos is the follow-up of the Megahit project. Its aim is to start implementing Megahit roadmaps,

by preparing demonstrators for a MWe class nuclear electric space propulsion. Democritos is funded by Horizon 2020, the R&T program of the European Commission.

It is a new European and Russian project, including as partners: Nuclear National Laboratory (U.K.), DLR (Germany), The Keldysh Research Center (Russia),

Thales Alenia Space Italia (Italy), Snecma (France), ESF (France) and CNES (France). IEAV (Brazil) will join as an observer.

Democritos will feature a technical part and a programmatic part.

Contents of the studies - 1 technical

DEMOCRITOS-GC (Ground Component): Detailed preliminary designs of ground demonstrator

• preliminary designs of all INPPS subsystems and ground based test benches • interaction of the major subsystems (thermal, power management, propulsion,

structures and conversion) between each other and with a (simulated) nuclear core providing high power (~100kW)

DEMOCRITOS-CC (Core Component): Nuclear reactor studies concepts of nuclear space reactor, specification of a core demonstrator including analysis of the regulatory and safety framework DEMOCRITOS-SC (Space Component): System architecture and robotic studies preliminary design of INPPS spacecraft, detailed assembly and servicing strategy in orbit

Contents of the studies - 2 programmatic

4) DEMOCRITOS-PO (Programmatic): Building an broader consortium to implement the demonstrator project Programmatic challenges: - To find and integrate to the consortium the best technical talents - To build a consortium as broad as possible to share technical and financial ressources - To find synergies with space and non-space existing programs - To propose an organizational and financial structure for the future demonstrators Means to achieve these goals: - Industrial and space agencies networks - Organization of a workshop with possible stakeholders - Coordination with ISEF and ISEC-G

International Context A growing international interest in nuclear electric applications

ISEC-G has identified nuclear power for electric propulsion and planetary surface application as a critical technology that could “yield novel approaches to and significantly increased capabilities for exploration mission” In Russia With the participation of Roscosmos and Rosatom [the state agencies for space exploration and nuclear power, respectively], the Keldysh Research Center is developing a spacecraft using a megawatt-class nuclear power propulsion system (NPPS), prototype expected completed in 2018. Energia will build the spacecraft that will be launched after 2025. KerC has expressed interest in providing test benchs for the Democritos demonstrator. In the United States NASA released last year a new annex for Design Reference Architecture (DRA) for Human Exploration of Mars. It includes an electronuclear design reference and chemical + solar design reference, and underscores the potential for both. No definitive choice between all the possible architectures. Electronuclear design allows the lowest number of SLS launches. NASA is developing Fission Power Systems (FPS) for use on the surface planets, and is building demonstrators. Although these demonstrators differ from what DEMOCRITOS proposes (10 kWe instead of 100 kWe, Stirling conversion instead of Brayton conversion), similarities exist in the logic and the objectives. Although few details are available on this project, China also claims to develop its own FPS

Project main steps

• Development logic of the demonstrators, with projects risk analysis. • Identify the requirements for each subsystem and the test benches. • Identify safety constrains imposed by a space nuclear power system. • Mission profile in case on-orbit validation is needed. • Select a general architecture for the demonstrators = good compromise between

test objectives and costs. • Prospection of possible international partners, in order to share costs and benefits.

Synergy with existing Russia nuclear demonstrators seems very promising. • January 2016: Workshop and bilateral contacts to broaden the consortium. • Preliminary design for the demonstrators and the test benches. Off-the-shelf

components preferred for components that are not critical technologies. • Propose a pre-phase zero design of a nuclear spacecraft.

• Define a programmatic plan, including governance structure, costing aspects and funding arrangements.

• Presentation at the next ISEF meeting.

Kick-off: march 2015

End: march 2017

Strategy on Technology maturity - 1 Target power for demonstrator: 100 kWe

Alternative: TA+MHD

Alternative: droplet radiator

Reference technologies were identified during Megahit: High TRL technologies, that can be available when demonstrator is built. Alternative technologies have been identified during Megahit: Low TRL technologies, that have improved performance, and would increase the assets of nuclear electric propulsion

Alternative: Liquid cooled fission reactor

Strategy on Technology maturity - 1

Reference technologies were identified during Megahit: High TRL technologies, that can be available when demonstrator is built. • Gas-cooled, highly enriched reactor, derived from ground applications. • Brayton conversion, using turbines and alternators from aeronautics, able to sustain 1200K-1300K • Heat pipes radiators • Low thrust Hall effect or ion thrusters, used in clusters • In orbit assembly similar to ISS First goal of the demonstrator: to demonstrate all reference techno can work together as a system. However reference technologies may have limited performance. Additional Technological maturity could be an asset.

Strategy on Technology maturity - 2

Alternative technologies have been identified during Megahit: Low TRL technologies, that have improved performance, and would increase the assets of nuclear electric propulsion • Liquid-cooled reactor, able of higher temperature, up to 1600K • Brayton conversion, with turbine using new materials (ceramics, nobium alloys) able of higher

temperature • Thermoacoustics + MHD as an alternative to Brayton • Droplet radiators • High thrust Electric thrusters, including MPD thrusters & Vasimr • Advanced robotic in-orbit assembly. Second Goal of the demonstrator: to participate to new technologies maturation Synergies possible with aeronautics, energy production on ground, and other space programs. Demonstrator should be modular, to accommodate reference technologies, then to accommodate alternative technologies Democritos consortium intends to propose new technology maturation within Horizon 2020.

Thermoacoustic: thermal -> acoustics

MHD: acoustics -> electrics

Conclusion

- Democritos = an opportunity for broad international cooperation Core consortium already exist with Megahit partners + Snecma. Megahit = a technical achievement that has built a European an Russian team dedicated to work together on Democritos. - Democritos = nuclear-electric propulsion, an exciting technological challenge on

system level, benefiting from rising interest in the international community, and offering the possibility to perform new missions of space exploration and earth protection.

- Democritos = possibility to mature and test new technologies, that could have

positive synergies in other area like aeronautics, ground energy production and other space programs, and that would consolidate stakeholders technological excellence.