Nuclear Power in Space

Transcription

1 Nuclear Power in Space Zara Hodgson 9 th International School on Nuclear Power, Warsaw, Poland 16 th November 2017

2 Introduction Zara Hodgson Chemical Engineer with over 15 years in nuclear Lead NNL s Research and Innovation Programme Lead team of chemical and process modellers Research interests are: Advanced recycling technology Spent fuel and nuclear material management Coated particle fuels Micro Reactors and reactors for space Fuel cycle evaluation 2

3 Introduction - NNL National Nuclear Laboratory Purpose: To serve the national interest and create value for our customers, by pushing the boundaries of science, technology and innovation 3

4 NNL Key Facts The principal R&D organisation to underpin UK s national nuclear programmes Workington Sellafield Preston Risley Stonehouse Culham 4

5 NNL supports the UK s entire civil nuclear fission programme Continued operation of existing reactors Legacy waste management / decommissioning New nuclear build Geological disposal Plutonium stockpile disposition Advanced reactor (Gen IV) and fuel cycle development Space Power systems Security, non-proliferation & safeguards 5

6 +90 o C in its subterranean ocean -220 o C at the icy surface Enceladus, orbiting Saturn Image courtesy of NASA 6

7 Image courtesy of REUTERS/NASA/Karl Kofoed 7

8 Image courtesy of NASA 8

9 Radioisotope Thermoelectric Generator Pellet Data 238 PuO d 93Np 0n 93Np Pu 151g 238 Pu per pellet 62.5 W th per clad pellet Iridium alloy cladding Operates at ~ 1400 C Image courtesy of NASA/US DoE

10 Americium-241 Half Life = 432 years α decay = MeV γ emission = kev Am Np y keV Images courtesy of BBC and FireAngel 10

11 Earth as a point of light between the icy rings of Saturn, taken by Cassini on 12 April 2017 Cassini was 1.4 billion kilometres away from Earth Image courtesy of NASA 11

12 Image taken on the ISS by ESA astronaut Thomas Pesquet, released 7 April 2017 Images courtesy of ESA 12

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14 Image courtesy of ESA 14

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16 Americium oxide successfully recovered by NNL 16

17 Image courtesy of Century Fox/The Martian 17

18 Image courtesy of NASA 18

19 SNAP 10-A : 0.59kWe, 43 days in space in 1965 Image courtesy of NASA 19

20 Prometheus project (2005); Conceptual design of a NEP spacecraft Image courtesy of NASA/JPL

21 Russian mega-watt class Nuclear Power Propulsion System (NPPS) prototype Expected completion in 2018 Image courtesy of KeRC 21

22 DEMOCRITOS 1 spacecraft 3 demonstrators Target Spacecraft Fission reactor Produces fission heat Conversion of heat into electricity: kwe using Helium-Xenon + PMAD (Heat pipes) Shield Shadow area Cluster of thrusters (20 x 50 kwe) hall-effect thrusters or ion thruster payload Propellant tanks (Xe or Kr) Core demonstrator heater 200 kwe Ground demonstrator Thrusters: 2x25 kwe IOV Technologies demonstrations 22

23 NEO deflection by acting as a gravity tractor. could deflect Apophis Asteroid trajectory by 1 million kilometer. If spacecraft leaves Earth in 2021, it would reach Apophis in 200 days and deflect it by staying a distance of 300m during 40 days. Image courtesy of CNES/Ill. P. Carril. 23

24 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. Image courtesy of CNES 24

25 Mars Curiosity self-portrait, 2014 Image courtesy of NASA Cargo support mission for manned Mars mission Could deliver 15t in 400 days 25

26 Outer solar system missions Image courtesy of NASA For Europa: 3 to 10t of payload in ~3 years For Titan: 3 to 12t of payload in 3.5 to 6 years 26

27 Reactor Requirements: ~1MW(e)/3MW(th) output Low launch mass and volume Limited post-launch maintenance requirements High degree of reliability (>10 years) and launch safety Image courtesy of NASA 27

28 Joules Horowitz Reactor (JHR), France ~750M European investment Image courtesy of CEA 28

29 Image courtesy of Century Fox/The Martian 29

30 Acknowledgement NNL for investment and support of the team ESA for funding the various radioisotope system studies. The work leading to part of this presentation has received funding from the European Union Seventh Framework Programme (FP7/ ) under grant agreement number and Horizon 2020 Programme under grant agreement number University of Leicester 30

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32 Why Nuclear Electric Propulsion? Why nuclear propulsion? Energy density of nuclear systems is considerably higher than fossil (chemically) systems lower mass of fuel required. Why electric propulsion? Since the early days of nuclear power, nuclear rocket engines have been considered Nuclear Thermal Propulsion NTP With electric thrusters (NEP) propellant is accelerated to considerably higher velocities requiring a smaller mass of propellant to be carried high specific impulse. NTP High thrust but short duration owing to mass of propellant required NEP Low thrust but high specific impulse long duration

33 Nuclear Electricity Generation in Space Previous studies have shown that a 1MWe system is required to generate the thrust levels to satisfy a reasonable range of missions. Second law of thermodynamics requires some heat to be rejected in order to convert heat into electricity (regardless of the technology used). Heat rejection in space can only be achieved by thermal radiation or by through the ejection of heated matter from the spacecraft.

34 MEGAHIT The EC FP7 MEGAHIT Project Objective of MEGAHIT Megawatt Highly Efficient Technologies for Space Power and Propulsion Systems for Long-duration Exploration Missions To construct a roadmap for nuclear electric in-space propulsion activities within the EC Horizon 2020 programme. Roadmap is to identify R&D needs for a 1MWe nuclearelectric propulsion (NEP) system.

35 DEMOCRITOS The EC Horizon 2020 DEMOCRITOS Project Objective of DEMOCRITOS The objective of DEMOCRITOS is to investigate the necessary demonstration activities in order to mature technologies for nuclear electric propulsion (NEP) systems. The work is based upon the roadmap issued in 2014 by the FP7-Space funded MEGAHIT project

36 Power conversion system options (Solid-state) Themoelectric Solid-state power conversion based on semiconductor material. No moving parts, very reliable Low conversion efficiency SP100 reactor: 2.4MWth produces 100kWe 4.17% Thermionic Solid-state works by boiling off electrons from a hot emitter plate and collecting them on a cooler collector plate. Suitable for low power applications Efficiencies are low but noow but could be higher with good material choices and reduction of space charge effect AMTEC - Alkali-Metal Thermal to Electric Converter Works by diffusion of alkali-metal ions through a solid electrolyte which is an insulator to electrons. Theoretical efficiency of about 40% but still low TRL Possible direct-cycle option for Li or Na-cooled reactors

37 Power conversion system options (Dynamic) Stirling Cycle Closed cycle piston engine working on the Stirling thermodynamic cycle. Good efficiencies but engineering is difficult to create tight tolerances and low-friction. Good for low to medium power applications Does not scale well to higher powers Brayton cycle Closed cycle recuperated gas turbine cycle. High TRL technology Hard to achieve high efficiency on small units Efficiency improves with unit size and scales well up to very large units. Rankine cycle closed liquid-vapour cycle Separating the liquid and vapour phases is problematic in microgravity An elaborate fluid would be required to operate at high temperature with reasonable pressure.