Sandia Lab's Nuclear-Powered UAV Project Leaked?

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while reading of Mr. Nozette unfortunate ending...


Secret Drone Technology Barred by “Political Conditions”
March 22nd, 2012 by Steven Aftergood


A certain technology that could extend the mission duration and capabilities of unmanned aerial vehicles (UAVs) was favorably assessed last year by scientists at Sandia National Laboratories and Northrop Grumman Systems Corporation. But they concluded regretfully that “current political conditions will not allow use of the results.”


The assessment was carried out to explore the feasibility of next generation UAVs. The objective was “to increase UAV sortie duration from days to months while increasing available electrical power at least two-fold,” according to a June 2011 Sandia project summary.


And that objective could have been achieved by means of the unidentified technology, which “would have provided system performance unparalleled by other existing technologies,” the project summary said.


“As a result of this effort, UAVs were to be able to provide far more surveillance time and intelligence information while reducing the high cost of support activities. This technology was intended to create unmatched global capabilities to observe and preempt terrorist and weapon of mass destruction (WMD) activities.”


But it was all for nought.


“Unfortunately, none of the results will be used in the near-term or mid-term future,” the project summary stated. “It was disappointing to all that the political realities would not allow use of the results.”


Not only that, but “none of the results can be shared openly with the public due to national security constraints.”


On close reading, it seems clear that the Sandia-Northrop project contemplated the use of nuclear technology for onboard power and propulsion.


The project summary, which refers to “propulsion and power technologies that [go] well beyond existing hydrocarbon technologies,” does not actually use the word “nuclear.” But with unmistakable references to “safeguards,” “decommissioning and disposal,” and those unfavorable “political conditions,” there is little doubt about the topic under discussion.


Furthermore, the project’s lead investigator at Sandia, the aptly named Dr. Steven B. Dron, is a specialist in nuclear propulsion, among other things. He co-chaired a session at the 2008 Symposium on Space Nuclear Power and Propulsion at the University of New Mexico.


Interestingly, opposition to flying nuclear power sources in this case was internalized without needing to be expressed, and the authors were self-deterred from pursuing their own proposals. “The results will not be applied/implemented,” they stated flatly.


Meanwhile, integration of (conventional) unmanned aircraft systems into the National Airspace System will proceed, as mandated by Congress. On March 6, the Federal Aviation Administration issued a request for public comments on the pending designation of six UAS test sites around the country.


Last month, the Electronic Privacy Information Center and other public interest organizations petitioned the FAA “to conduct a rulemaking to address the threat to privacy and civil liberties that will result from the deployment of aerial drones within the United States.”


http://www.fas.org/blog/secrecy/2012/03/sandia_drone.html
http://www.fas.org/irp/eprint/sand-uav.pdf
 
Orionblamblam said:
I wonder if maybe there was some success with hafnium isomers after all.

"Interestingly, opposition to flying nuclear power sources in this case was internalized without needing to be expressed, and the authors were self-deterred from pursuing their own proposals."

That sounded. . .ominous. Almost as if the author was pleased that "they saw the error of their ways without anybody needing to point it out for them".
 
sferrin said:
That sounded. . .ominous. Almost as if the author was pleased that "they saw the error of their ways without anybody needing to point it out for them".

Couple ways to take it:
1) "Holy crap, what we've come up with would work, but it'd be an environmental nightmare."
2) "Holy crap, what we've come up with would work, but it would require flying full-up fission reactors, and that just ain't gonna happen. Let's waste no further effort on this."
3) "Holy crap, what we've come up with wouldn't work worth a damn, but we'd better cover our butts with the higher-ups. Let's lie!"
4) "Holy crap, what we've come up with wouldn't work worth a damn, but if we drop vague hints, we can cause our enemies to waste time and effort trying to figure it out. Let's lie!"
5) "I'm bored. We've done nothing, but if we drop hints of Great Advancements, we'll make the UFO freaks go bugnuts. Let's lie!"
 
http://en.wikipedia.org/wiki/Advanced_Stirling_Radioisotope_Generator
 
So is the political problem the mess that the Plutonium238 would make when one crashed/shot down, or that we would have to buy the Plutonium from Russia since we don't make it any more?
 
sublight said:
So is the political problem the mess that the Plutonium238 would make when one crashed/shot down, or that we would have to buy the Plutonium from Russia since we don't make it any more?

There is plenty of 238, and it's not like it's going away soon.
 
Surely there are applications other than UAV's, ones which are less prone to crashing and either....
  • releasing a radiological nightmare (apologies, gone a bit Annie Jacobson with my language there ::) )
  • unintended technology transfers (need to bomb the crash site back to the stone age.... yadda yadda yadda)
Hafnium isomers was my first thought too.
 
I was speculating that there must be applications for such a groundbreaking power source that doesn't involve flying (or even worse crashing).

Maybe the political considerations are the risk of crop dusting the earth with a radioactive exhaust. I'd prefer to believe however that Sandia & Northrop had thought about that at the project kick off meeting...
 
Quellish, do you think you could get acceptable power/weight out of that system?

What I had heard (before this) was that the UAV and nuclear power went together because (1) nobody wants to fly for a week, much less a month and (2) long-term shielding of the crew drove the weight. If you recall the original hafnium-isomer Global Hawk idea, too, the idea was to burn JP for take-off, climb, descent and landing.

People have been quite serious about this, but its political chances are zero.
 
quellish said:
sublight said:
So is the political problem the mess that the Plutonium238 would make when one crashed/shot down, or that we would have to buy the Plutonium from Russia since we don't make it any more?

There is plenty of 238, and it's not like it's going away soon.
Available to whom? The last seven or eight times NASA needed it, they had to buy it from Russia.
 
LowObservable said:
Quellish, do you think you could get acceptable power/weight out of that system?

What I had heard (before this) was that the UAV and nuclear power went together because (1) nobody wants to fly for a week, much less a month and (2) long-term shielding of the crew drove the weight. If you recall the original hafnium-isomer Global Hawk idea, too, the idea was to burn JP for take-off, climb, descent and landing.

People have been quite serious about this, but its political chances are zero.

According to the report, they looked at:
"eight heat sources technologies, three power conversions, two dual cycle propulsion system configurations, and a single electrical power generation scheme". I would guess that there may be a separate cycle for takeoff and landing, that would make a lot of sense.

Supposedly an ASRG has/can have the power to weight to enable use for this type of application. It's been looked at for a Titan mission UAV:
http://www.lpi.usra.edu/opag/Oct2011/presentations/1_AVIATR_Barnes.pdf
From other open source information on ASRGs, it seems that some very good power to weight is possible.
And hey, if you leave out the shielding....

RTGs in general are used more than you would think for terrestrial applications. Sometimes they get disguised as rocks ;)
 
sublight said:
quellish said:
sublight said:
So is the political problem the mess that the Plutonium238 would make when one crashed/shot down, or that we would have to buy the Plutonium from Russia since we don't make it any more?

There is plenty of 238, and it's not like it's going away soon.
Available to whom? The last seven or eight times NASA needed it, they had to buy it from Russia.

Well, for non national security use:

http://nuclear.inl.gov/spacenuclear/docs/final72005faqs.pdf
http://www.nukewatch.org/facts/nwd/nwnmpu238082905.pdf

Otherwise, I could tell you but then I'd have to kill you.
You can however draw your own conclusions from documents such as this:
http://www.ccnr.org/plute_inventory_99.html
http://nnsa.energy.gov/ourmission/managingthestockpile/plutoniumpits
http://www.armscontrol.org/act/2007_10/PlutoniumStockpile
http://fissilematerials.org/library/gfmr11.pdf
 
Quellish quite correctly indicated ASRG has been looked at for a Titan mission UAV.
If an ASRG was involved in one or more of the options considered in the Sandia study then we can assume the authors of the Sandia report do not see space exploration as being of benefit to the taxpayer or they are not optimistic about the Titan mission happening anytime soon.....No near-term benefit to industry or the taxpayer will be encountered as a result of these studies." :mad:

Specifically Regarding the Titan mission UAV, is the application of an ARSG more viable on Titan than on Earth?


"With 3.25 times more air and 7 times less gravity than Earth, along with a workable thermal environment, heavier-than-air flight makes more sense on Titan than anywhere else in the solar system".
http://www.lpi.usra.edu/opag/Oct2011/presentations/1_AVIATR_Barnes.pdf


Edited highlights from the Sandia report below

Description:
The purpose/objective of the project was to further ultra-persistence technologies for unmanned air vehicles (UAVs). This effort was broken into four task areas:

Task 1 - UP3S Systems Engineering Analyses (UP3S = ultra-persistent propulsion and power system)
Task 2 - UP3S Project Planning
Task 3 - Briefing Support
Task 4 - Interim and Final Reports.

Under task 1, Sandia conducted computer-based engineering and literature-based process analyses to meet the technical and programmatic requirements. Sandia assisted NGIS UMS to baseline at least one future UAV configuration with new energy and power systems to meet emerging U.S. military operational needs. Sandia conducted analyses at component and system-levels that emerged during the project. No physical asset testing or demonstrations was performed during this effort.

Under task 2, Sandia and NGIS UMS developed technology development requirements, projected costs, schedule, manpower, facilities, equipment, associated resources, key experiments, demonstrations, tests, and decisions, operational system modifications versus new system acquisition

Accomplishments
The effort concentrated on propulsion and power technologies that went well beyond existing hydrocarbon technologies. It contrasted and compared eight heat sources technologies, three power conversion, two dual cycle propulsion system configurations, and a single electrical power generation scheme. Overall performance, specific power parameters, technical complexities, security, safety, and other operational features were successfully investigated. Large and medium sized UAV systems were envisioned and operational flight profiles were developed for each concept.

Benefits to the Department of Energy:
None of the results are currently in use by DOE and it is doubtful that they will be used in the near-term or mid-term future. Currently, none of the results can be shared openly with the public due to national security constraints.

Economic Impact:

No near-term benefit to industry or the taxpayer will be encountered as a result of these studies.
 
sublight said:
quellish said:
sublight said:
So is the political problem the mess that the Plutonium238 would make when one crashed/shot down, or that we would have to buy the Plutonium from Russia since we don't make it any more?

There is plenty of 238, and it's not like it's going away soon.
Available to whom? The last seven or eight times NASA needed it, they had to buy it from Russia.

Only two times.
 
sublight said:
quellish said:
sublight said:
So is the political problem the mess that the Plutonium238 would make when one crashed/shot down, or that we would have to buy the Plutonium from Russia since we don't make it any more?

There is plenty of 238, and it's not like it's going away soon.
Available to whom? The last seven or eight times NASA needed it, they had to buy it from Russia.

NASA has very little Pu-238 left.

Pu-238 is manufactured from Neptunium. The DoE has plenty of Neptunium in storage. The issue is restarting production to convert the Neptunium into Pu-238.
 
quellish said:
Supposedly an ASRG has/can have the power to weight to enable use for this type of application. It's been looked at for a Titan mission UAV:

Titan has lower gravity than Earth and a thicker atmosphere.
 
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080003866_2008003415.pdf

Note that obviously this is focused on space applications (for planetary missions), and only covers fairly small generators.

blackstar said:
Titan has lower gravity than Earth and a thicker atmosphere.

Atmosphere? Pfft. That place is dead after 10PM. Salt Lake City has more atmosphere!
 
Didn't find this mentioned elsewhere on the forum, but TEAL RAIN looked at several different nuclear propulsion systems (RTG and "other") back in the early 80s. IIRC Livermore was part of this effort.
 
From the Sandia report,

The stated goal of an ultra-persistent propulsion and power system (UP3S) was "for potential incorporation into next generation UAV systems. The team members tried to determine which energy storage and power generation concepts could most effectively push UAV propulsion and electrical power capabilities to increase UAV sortie duration from days to months while increasing available electrical power at least two-fold". The report also states NGIS UMS and SNL felt that the technical goals for the project were accomplished

Under task 1 (computer-based engineering and literature-based analyses) the Sandia report talks of "Propulsion and power system scalability"
Presumably this refers to the feasibility of applying something like RTG's, ASRG's etc of sufficient power (and viable size) to provide propulsion for months and double electrical power.

The report also talks of some accomplishments of Cooperative Research and Development Agreement (#1714), which include
  • Baselineing at least one future UAV configuration with the proposed new energy and power systems
  • Large and medium sized UAV systems were envisioned
Soooo, as Large UAV's were envisioned......

1.
Taking a current Large UAV (RQ-4B Block 40) using current hydrocarbon technology
2. Only considering the electrical power output (e.g. on RQ-4B Block 40, a 25kVA generator). Can we hypothesise that electrical power generation for an envisioned Large UAV's using the proposed new energy and power systems would be double that of RQ-4B?

50 kVA = 40 kW

Using this logic (which admittedly is shaky) and considering the ASRG hypothesis

http://en.wikipedia.org/wiki/Advanced_Stirling_Radioisotope_Generator
ASRG example discussed above weighs 20Kg, uses 0.8 kg plutonium-238 and produces 140 W. Using a linear scaling (this is probably where I've completely missunderstood the principles), I'm not surprised flying 230 kg of plutonium-238 on a UAV is considered to be a "politically reality that would not allow use of results"


One last final comment (which again probably only comes down to definitions), regarding the eight heat source technologies studied, to me plutonium bricks would be one heat source... what are the other 7?
 
Catalytic said:
From the Sandia report,

The stated goal of an ultra-persistent propulsion and power system (UP3S) was "for potential incorporation into next generation UAV systems. The team members tried to determine which energy storage and power generation concepts could most effectively push UAV propulsion and electrical power capabilities to increase UAV sortie duration from days to months while increasing available electrical power at least two-fold". The report also states NGIS UMS and SNL felt that the technical goals for the project were accomplished

Under task 1 (computer-based engineering and literature-based analyses) the Sandia report talks of "Propulsion and power system scalability"
Presumably this refers to the feasibility of applying something like RTG's, ASRG's etc of sufficient power (and viable size) to provide propulsion for months and double electrical power.

The report also talks of some accomplishments of Cooperative Research and Development Agreement (#1714), which include
  • Baselineing at least one future UAV configuration with the proposed new energy and power systems
  • Large and medium sized UAV systems were envisioned
Soooo, as Large UAV's were envisioned......

1.
Taking a current Large UAV (RQ-4B Block 40) using current hydrocarbon technology
2. Only considering the electrical power output (e.g. on RQ-4B Block 40, a 25kVA generator). Can we hypothesise that electrical power generation for an envisioned Large UAV's using the proposed new energy and power systems would be double that of RQ-4B?

50 kVA = 40 kW

Using this logic (which admittedly is shaky) and considering the ASRG hypothesis

http://en.wikipedia.org/wiki/Advanced_Stirling_Radioisotope_Generator
ASRG example discussed above weighs 20Kg, uses 0.8 kg plutonium-238 and produces 140 W. Using a linear scaling (this is probably where I've completely missunderstood the principles), I'm not surprised flying 230 kg of plutonium-238 on a UAV is considered to be a "politically reality that would not allow use of results"


One last final comment (which again probably only comes down to definitions), regarding the eight heat source technologies studied, to me plutonium bricks would be one heat source... what are the other 7?
But it could also be that they made some really fantastic gains in sterling engine efficiencies. Maybe in the 200 watts per kilogram range?
 
Catalytic said:
One last final comment (which again probably only comes down to definitions), regarding the eight heat source technologies studied, to me plutonium bricks would be one heat source... what are the other 7?

That is the key question. Pu 238 may not cut it for this kind of application. A more energetic source can put out a LOT more heat per g than Pu 238.

Of course, if you were flying a NPT monitoring mission over country X using this thing, well, you wouldn't want ANY of these things ending "lost". Some of the heat sources with really good power density also make really good initiators for implosion bombs.

sublight said:
But it could also be that they made some really fantastic gains in sterling engine efficiencies. Maybe in the 200 watts per kilogram range?

Not really. The SunPower stirling engines are right up against the limits of practical, the limits of theoretical aren't that far beyond that from what I understand. SunPower has a unique approach to designing their engines that gets them an efficiency advantage.
http://discovermagazine.com/2003/aug/featfire/?searchterm=idealab

The NASA paper covers some of this.
 
Economically it doesn't make sense. Radioisotopes costs millions per kg and power to weight ratio usually sucks unless if you want to go for the REALLY radioactive stuff that then needs additional heavy shielding. The added price will never justify the added military value and there's only enough of the material anyway for maybe four or five rather smallish UAVs. But hey, it's the military, since when did economics matter?
 
quellish said:
Of course, if you were flying a NPT monitoring mission over country X using this thing, well, you wouldn't want ANY of these things ending "lost". Some of the heat sources with really good power density also make really good initiators for implosion bombs.

Doesn't even have to be a good initiator for a bomb. Anything radioactive can be used in a dirty bomb. Would we really want to hand the Iranians some radioactive material that they might return to us in a bomb detonated in downtown NYC?
 
Simon666 said:
Economically it doesn't make sense. Radioisotopes costs millions per kg and power to weight ratio usually sucks unless if you want to go for the REALLY radioactive stuff that then needs additional heavy shielding.
The added price will never justify the added military value and there's only enough of the material anyway for maybe four or five rather smallish UAVs. But hey, it's the military, since when did economics matter?

Some of the best heat sources are radioisotopes that are very energetic, and as such have a short half life. These are also good neutron sources, and are the same materials used in the initiators of many atomic devices. A short half life means a short shelf life. It is reasonable to conclude that for these materials, there is an existing production capacity available to maintain the current atomic device stockpile. This production capacity may be able to meet the needs of the heat sources that were part of the Sandia study.

The power to weight ratio for the heat source can be very good, depending on the heat source. If you factor in the other potential weight savings for an application like this, it can be very a very attractive solution.
 
Some of the best heat sources are radioisotopes that are very energetic, and as such have a short half life. These are also good neutron sources, and are the same materials used in the initiators of many atomic devices.
The short half lives also means short shelf life and great expense and limited production. Being very energetic also means cost of processing and shielding is also more problematic. For atomic devices, you need very little of this stuff, not remotely near the quantity you'd need to power anything. For very high power to weight ratio you also have to consider the power is continuous so your cooling better be as well in any and all circumstances.
 
From an Army soldier systems powerplant study.
 

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Very interesting, thanks. I had seen a study of various alternative isotopes for space missions. The excerpt of the one you posted is quite interesting. Especially table 5c, which already eliminates a lot of the isotopes of previous tables (link to full study to see actual selection criteria?). Availability still seems quite little and cost per watt of course needs to be divided by expected efficiency (thermal to work efficiency of 25% = *4) and adjusted for inflation. Cost per kW is hence immense.

<edit>Po 210 REALLY surprises me in both the cost and availability department. Considering its very short half life, I had expected a lot worse. Wikipedia tells me Russia only produces 85 grams per year and the way it is produced also leads me to suspect price is higher than in the table.</edit>
 
Simon666 said:
Very interesting, thanks. I had seen a study of various alternative isotopes for space missions. The excerpt of the one you posted is quite interesting. Especially table 5c, which already eliminates a lot of the isotopes of previous tables (link to full study to see actual selection criteria?). Availability still seems quite little and cost per watt of course needs to be divided by expected efficiency (thermal to work efficiency of 25% = *4) and adjusted for inflation. Cost per kW is hence immense.

The efficiency for a modern Stirling engine is pretty good. For this particular application, the overall system efficiency should be very good. Cost per kW may not be as high as you would think, and there are ways to recover what would otherwise be waste heat for this application. Most of the public studies on radioisotope thermal power focus on very small systems in terms of both mass and power output, with different solutions the scaling laws are different. Also keep in mind that HALSOL measured its power output in the low kW range, and it was carrying solar panels, batteries, etc. An aircraft powered by a RT system that delivers both mechanical output and electrical power would have some advantages.

Simon666 said:
<edit>Po 210 REALLY surprises me in both the cost and availability department. Considering its very short half life, I had expected a lot worse. Wikipedia tells me Russia only produces 85 grams per year and the way it is produced also leads me to suspect price is higher than in the table.</edit>

There are apparently multiple ways to produce it, some not so well known. It possible that someone was also pushing this study as a justification for maintaining or expanding the production capabilities for some of the heat sources.
 
The study raises what should/could be considered HUGE questions if they are not just attempts justify or maintain or expand the production capabilities for some of the heat sources as Quellish states.
 
AW&ST/DTI article with some technical detail from Bill S:

http://www.aviationweek.com/Article.aspx?id=/article-xml/DT_05_01_2012_p14-450521.xml

Benefits Of Nuclear UAVs
By Bill Sweetman
Source: Defense Technology International

May 01, 2012
In March, Sandia National Laboratories released a summary of research it had conducted with Northrop Grumman's unmanned systems division concerning an “ultra-persistent propulsion and power system” for unmanned aerial vehicles (UAV). The conclusion was that UAVs could be built with longer endurance and lower operating cost than with hydrogen or hydrocarbon fuel, creating “unmatched global capabilities to observe and preempt terrorist and weapon of mass destruction activities.”

An earlier Sandia study concluded that such a UAV could be tested within a decade. It will not be, because it is nuclear-powered, and politics make it impossible. But the technical and operational case is powerful.

Non-solar-powered UAVs, such as Boeing's hydrogen-fueled Phantom Eye and Aurora Flight Sciences' Orion, are expected to deliver multi-day endurance. But they cannot carry large payloads or provide much electrical power, and are slow, so have to be forward-based. They are also restricted to propeller propulsion, which makes stealth unattainable.

The Sandia-Northrop activity is linked to studies of nuclear-powered UAVs in the U.S. Air Force that started in the mid-1990s, not long after the Advanced Airborne Reconnaissance System, a conventionally powered long-endurance stealth drone planned in the 1980s to track Soviet mobile nuclear missiles, was terminated.

Sandia was heavily involved by 2001. A paper from the Center for Strategic and Budgetary Assessments noted that Sandia's Special Projects Department had proposed an “extremely long-endurance vehicle (ELEV)” or “air-breathing satellite.” The ELEV could fly at 70,000 ft. and stay on station for six months to a year with up to a 5,000-lb. payload. According to Sandia, building a modern nuclear-turbojet engine “would not be an R&D project,” the CSBA report stated, “but rather an engineering development effort that could culminate in a flight test within a decade.”

Boeing's Phantom Works was involved with the design of the nuclear UAV, a high-subsonic, blended-wing body. Propulsion was based on concepts that emerged from the Airborne Nuclear Power (ANP) program of the 1950s, which was intended to lead to a strategic missile carrier that would remain on continuous airborne alert for a week or more. It combined two turbojet engines with a reactor. ANP looked at two designs: “direct cycle,” in which the engine airflow cooled the reactor; and “indirect cycle,” in which a liquid-metal coolant carried heat from the reactor to the engine.

The 2000-era UAV enjoyed three advantages over ANP, which struggled to reach a performance level where the aircraft could fly. Two stemmed from the fact that it was a UAV, which could take advantage of the propulsion system's endurance. Planners envisioned features such as magnetic engine bearings to eliminate oil. Importantly, more than half the weight of the ANP propulsion system was radiation shielding, which could be reduced in a system that would not run at full power near humans. (In the Sandia studies, the engines burned jet fuel for takeoff and landing.) A USAF study of a Global Hawk with a nuclear engine indicated it might need only 2,700 lb. of shielding.

The third advantage was improved reactor technology. Air Force interest in ELEV coincided with the winding-down of the Space Nuclear Thermal Propulsion technology program, in which Sandia was also involved. SNTP started in 1987 as the Strategic Defense Initiative Office's Project Timberwind, aimed at producing a nuclear-thermal rocket (developing thrust by superheating hydrogen) for a missile interceptor, but was canceled after the Cold War. A Timberwind rocket engine would have incorporated a particle bed reactor (PBR), with some designs weighing as little as 2,000 lb., using carbon-carbon and ceramic-matrix composites.

New reactor designs are safer. They “would only hurt you if they fell on you,” it has been suggested, because of specially fabricated and shielded fuel elements and robust “poison” systems to perform an emergency shutdown. It is not known whether a PBR or a different modern reactor technology was the basis for the ELEV concept or the Sandia-Northrop Grumman study, which covered eight heat sources, three power conversion systems, two dual-cycle propulsion systems and an electrical generation system. However, it was stated in 2001 that the propulsion system would power the aircraft while delivering several hundred kilowatts to onboard radar, communications and electronic attack systems. Conventional turbine engines optimized for range and fuel consumption and sized for typical UAVs struggle to deliver 50+ kw at altitude.
 
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Hmmm, perhaps in future a 9th "heat source" could be added to the mysterious 8 studied previously

Skunk Works Reveals Compact Fusion Reactor Details
October 21, 2014 by

Lockheed Martin aims to develop compact reactor prototype in five years, production unit in 10

Guy Norris | Aviation Week & Space Technology

Hidden away in the secret depths of the Skunk Works, a Lockheed Martin research team has been working quietly on a nuclear energy concept they believe has the potential to meet, if not eventually decrease, the world’s insatiable demand for power.

Dubbed the compact fusion reactor (CFR), the device is conceptually safer, cleaner and more powerful than much larger, current nuclear systems that rely on fission, the process of splitting atoms to release energy. Crucially, by being “compact,” Lockheed believes its scalable concept will also be small and practical enough for applications ranging from interplanetary spacecraft and commercial ships to city power stations. It may even revive the concept of large, nuclear-powered aircraft that virtually never require refueling—ideas of which were largely abandoned more than 50 years ago because of the dangers and complexities involved with nuclear fission reactors.

CFR test team
The CFR test team, led by Thomas McGuire (left), is focusing on plasma containment following successful magnetized ion confinement experiments. Credit: Eric Schulzinger/Lockheed Martin
Yet the idea of nuclear fusion, in which atoms combine into more stable forms and release excess energy in the process, is not new. Ever since the 1920s, when it was postulated that fusion powers the stars, scientists have struggled to develop a truly practical means of harnessing this form of energy. Other research institutions, laboratories and companies around the world are also pursuing ideas for fusion power, but none have gone beyond the experimental stage. With just such a “Holy Grail” breakthrough seemingly within its grasp, and to help achieve a potentially paradigm-shifting development in global energy, Lockheed has made public its project with the aim of attracting partners, resources and additional researchers.

Although the company released limited information on the CFR in 2013, Lockheed is now providing new details of its invention. Aviation Week was given exclusive access to view the Skunk Works experiment, dubbed “T4,” first hand. Led by Thomas McGuire, an aeronautical engineer in the Skunk Work’s aptly named Revolutionary Technology Programs unit, the current experiments are focused on a containment vessel roughly the size of a business-jet engine. Connected to sensors, injectors, a turbopump to generate an internal vacuum and a huge array of batteries, the stainless steel container seems an unlikely first step toward solving a conundrum that has defeated generations of nuclear physicists—namely finding an effective way to control the fusion reaction.

“I studied this in graduate school where, under a NASA study, I was charged with how we could get to Mars quickly,” says McGuire, who earned his Ph.D. at the Massachusetts Institute of Technology. Scanning the literature for fusion-based space propulsion concepts proved disappointing. “That started me on the road and [in the early 2000s], I started looking at all the ideas that had been published. I basically took those ideas and melded them into something new by taking the problems in one and trying to replace them with the benefits of others. So we have evolved it here at Lockheed into something totally new, and that’s what we are testing,” he adds.

To understand the breakthroughs of the Lockheed concept, it is useful to know how fusion works and how methods for controlling the reaction have a fundamental impact on both the amount of energy produced and the scale of the reactor. Fusion fuel, made up of hydrogen isotopes deuterium and tritium, starts as a gas injected into an evacuated containment vessel. Energy is added, usually by radio-frequency heating, and the gas breaks into ions and electrons, forming plasma.

The superhot plasma is controlled by strong magnetic fields that prevent it from touching the sides of the vessel and, if the confinement is sufficiently constrained, the ions overcome their mutual repulsion, collide and fuse. The process creates helium-4, freeing neutrons that carry the released energy kinetically through the confining magnetic fields. These neutrons heat the reactor wall which, through conventional heat exchangers, can then be used to drive turbine generators.

Until now, the majority of fusion reactor systems have used a plasma control device called a tokamak, invented in the 1950s by physicists in the Soviet Union. The tokamak uses a magnetic field to hold the plasma in the shape of a torus, or ring, and maintains the reaction by inducing a current inside the plasma itself with a second set of electromagnets. The challenge with this approach is that the resulting energy generated is almost the same as the amount required to maintain the self-sustaining fusion reaction.

reactor rings
Neutrons released from plasma (colored purple) will transfer heat through reactor walls to power turbines. Credit: Lockheed Martin
An advanced fusion reactor version, the International Thermonuclear Experimental Reactor (ITER), being built in Cadarache, France, is expected to generate 500 MW. However, plasma is not due to be generated until the late 2020s, and derivatives are not likely to be producing significant power until at least the 2040s.

The problem with tokamaks is that “they can only hold so much plasma, and we call that the beta limit,” McGuire says. Measured as the ratio of plasma pressure to the magnetic pressure, the beta limit of the average tokamak is low, or about “5% or so of the confining pressure,” he says. Comparing the torus to a bicycle tire, McGuire adds, “if they put too much in, eventually their confining tire will fail and burst—so to operate safely, they don’t go too close to that.” Aside from this inefficiency, the physics of the tokamak dictate huge dimensions and massive cost. The ITER, for example, will cost an estimated $50 billion and when complete will measure around 100 ft. high and weigh 23,000 tons.

The CFR will avoid these issues by tackling plasma confinement in a radically different way. Instead of constraining the plasma within tubular rings, a series of superconducting coils will generate a new magnetic-field geometry in which the plasma is held within the broader confines of the entire reaction chamber. Superconducting magnets within the coils will generate a magnetic field around the outer border of the chamber. “So for us, instead of a bike tire expanding into air, we have something more like a tube that expands into an ever-stronger wall,” McGuire says. The system is therefore regulated by a self-tuning feedback mechanism, whereby the farther out the plasma goes, the stronger the magnetic field pushes back to contain it. The CFR is expected to have a beta limit ratio of one. “We should be able to go to 100% or beyond,” he adds.

This crucial difference means that for the same size, the CFR generates more power than a tokamak by a factor of 10. This in turn means, for the same power output, the CFR can be 10 times smaller. The change in scale is a game-changer in terms of producibility and cost, explains McGuire. “It’s one of the reasons we think it is feasible for development and future economics,” he says. “Ten times smaller is the key. But on the physics side, it still has to work, and one of the reasons we think our physics will work is that we’ve been able to make an inherently stable configuration.” One of the main reasons for this stability is the positioning of the superconductor coils and shape of the magnetic field lines. “In our case, it is always in balance. So if you have less pressure, the plasma will be smaller and will always sit in this magnetic well,” he notes.

Overall, McGuire says the Lockheed design “takes the good parts of a lot of designs.” It includes the high-beta configuration, the use of magnetic field lines arranged into linear ring “cusps” to confine the plasma and “the engineering simplicity of an axisymmetric mirror,” he says. The “axisymmetric mirror” is created by positioning zones of high magnetic field near each end of the vessel so that they reflect a significant fraction of plasma particles escaping along the axis of the CFR. “We also have a recirculation that is very similar to a Polywell concept,” he adds, referring to another promising avenue of fusion power research. A Polywell fusion reactor uses electromagnets to generate a magnetic field that traps electrons, creating a negative voltage, which then attracts positive ions. The resulting acceleration of the ions toward the negative center results in a collision and fusion.

The team acknowledges that the project is in its earliest stages, and many key challenges remain before a viable prototype can be built. However, McGuire expects swift progress. The Skunk Works mind-set and “the pace that people work at here is ridiculously fast,” he says. “We would like to get to a prototype in five generations. If we can meet our plan of doing a design-build-test generation every year, that will put us at about five years, and we’ve already shown we can do that in the lab.” The prototype would demonstrate ignition conditions and the ability to run for upward of 10 sec. in a steady state after the injectors, which will be used to ignite the plasma, are turned off. “So it wouldn’t be at full power, like a working concept reactor, but basically just showing that all the physics works,” McGuire says.

superconducting magnet rings
Rings containing superconducting magnets will confine the plasma inside the reaction chamber. Credit: Eric Schulzinger/Lockheed Martin
An initial production version could follow five years after that. “That will be a much bigger effort,” he says, suggesting that transition to full-scale manufacturing will necessarily involve materials and heat-transfer specialists as well as gas-turbine makers. The early reactors will be designed to generate around 100 MW and fit into transportable units measuring 23 X 43 ft. “That’s the size we are thinking of now. You could put it on a semi-trailer, similar to a small gas turbine, put it on a pad, hook it up and can be running in a few weeks,” McGuire says. The concept makes use of the existing power infrastructures to enable the CFR to be easily adapted into the current grid. The 100-MW unit would provide sufficient power for up to 80,000 homes in a power-hungry U.S. city and is also “enough to run a ship,” he notes.

Lockheed estimates that less than 25 kg (55 lb.) of fuel would be required to run an entire year of operations. The fuel itself is also plentiful. Deuterium is produced from sea water and is therefore considered unlimited, while tritium is “bred” from lithium. “We already mine enough lithium to supply a worldwide fleet of reactors, so with tritium you never have too much built up, and that’s what keeps it safe. Tritium would be a health risk if there were enough released, but it is safe enough in small quantities. You don’t need very much to run a reactor because it is a million times more powerful than a chemical reaction,” McGuire notes.

Although the first-generation reactors will have radioactive parts at the ends of their lives, such as some steel elements in the shell, McGuire says the contamination situation “is an order of magnitude better” than that of contemporary fission systems. “There is no long-lived radiation. Fission reactors’ stuff will be there forever, but with fusion materials, after 100 years then you are good.” Contamination levels for fusion will improve with additional materials research, he believes. “It’s been a chicken-and-egg situation. Until we’ve had a good working fusion system, there has not been money to go off and do the hard-core materials research,” McGuire says. “So we believe the first generation is good enough to go out and do, and then it will only improve in time.” Old CFR steel shell parts can be disposed of with “a shallow burial in the desert, similar to medical waste today. That’s a major difference to today’s fission systems.”

Operational benefits include no risks of suffering a meltdown. “There is a very minimal amount of radioactive tritium—it’s on the order of grams—so the potential release is very minimal. In addition, there is not enough to be a risk of proliferation. Tritium is used in nuclear weapons but in a much larger inventory than would be involved here, and that’s because you are continually making just enough to feed back in [to maintain the reaction],” he adds.

Preliminary simulations and experimental results “have been very promising and positive,” McGuire says. “The latest is a magnetized ion confinement experiment, and preliminary measurements show the behavior looks like it is working correctly. We are starting with the plasma confinement, and that’s where we are putting most of our effort. One of the reasons we are becoming more vocal with our project is that we are building up our team as we start to tackle the other big problems. We need help and we want other people involved. It’s a global enterprise, and we are happy to be leaders in it.”
 
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In the light of recent events ;) I wonder if the political considerations that (apparently) killed this work are being reconsidered.
 
I wouldn't be surprised, though in the short term any work may not get far due to the Democrats retaking the House of Representatives.
 
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