SCO reactor project

OK its not classified.

high-assay low enriched uranium (HALEU) advance gas reactor (AGR) tristructural isotropic (TRISO) fuel.

high-assay low enriched uranium (HALEU) advance gas reactor (AGR) tristructural isotropic (TRISO) fuel.

Interesting times.

originally posted by: whywhynot
a reply to: Zaphod58

One would believe that the government wouldn’t waste time on impossible projects however the amount of cooling air flow required for a net 10 mwhr output would be enormous. No way it would fly, pun intended, with our present understanding of physics.

Imho

That's true, only if you believe boiled water reactors are what nuclear reactor technology is.

In truth, boiled water reactors are the most primitive, dangerous and ineffective way to split atoms for energy.

There are much safer and better ways to generate nuclear power... like pebble bed reactors, and especially thorium salt reactors... both of which have been designed in a manner that by definition, are incapable of going critical.

More here on Molten Salt Reactors... really fascinating read.

I'm a little perplexed b/c as far as I know/remember this entire endeavor has already been done (ORNL ~1964) for the most part but it used a different fuel (thorium) and was successful. IDK if the fuel they are planning on using is specifically needed or if another fuel would suffice, but I've read a number of research articles on the molten salt reactors and they seem like the most promising technologies and with the advent of new materials (especially titanium alloys in place of Hastelloy-N or Inconel would probably greatly reduce weight while increasing temp thresholds).

These reactors were originally proposed to be used for both military applications as well as a form of "municipal nuclear" where reactors could be built in cities/towns, possibly even underground, and used for very long periods with extreme safety.

Does anyone know why they are planning to use 5-20% enriched uranium?

How do the nuclear reactors on subs/ships compare in size with the one they want to build, in terms of size. I suspect many of them produce more than the 10Mw of power (do they have a need/use for the thermal energy produced by this new reactor, b/c if they can use some of that 20-30Mw themal energy then that would GREATLY reduce the cooling "cost" and would make this project much easier to realize).

a reply to: DigginFoTroof

We actually discussed ship based reactors. The point was brought up that they tend to be surrounded by lots and lots of water as part of their environment.

originally posted by: Zaphod58
a reply to: DigginFoTroof

We actually discussed ship based reactors. The point was brought up that they tend to be surrounded by lots and lots of water as part of their environment.

Which is why I mentioned whether there was any plan for the use of the thermal heat from the reactor. I wouldn't put it past the people who wrote the RFI to either be unaware of aspects of nuclear energy or even the complete intended use of the reactor.

If this is meant to power FOB's, small "towns" (bases, research facilities, etc) then thermal energy will be needed in those locations for heating (air/water) and can even be used for cooling (freezers, refrigerators, AC, with absorption cooling) which, if they had planned to use electric means for all heating/cooling then they could drastically reduce the amount of electricity required by the reactor while still getting more than enough heating and cooling from the device.

Back when cities used steam to heat buildings, it was most cost effective to place power plants in the center of the city b/c they could use the "waste" heat of the plant to heat the buildings. As things moved away from this, power plants needed to be much larger (2-4x in size) b/c electric heat was used and the "waste" heat was thrown away. Absolutely ridiculous and a sign of a society that doesn't plan for the future.

originally posted by: Slichter
They were talking about micro-fusion reactors 50 years ago, but

nanowires made out of a material called deuterated polyethylene

is new. Must still be classified it it exists. You can make very efficient reactors that require little cooling theoretically.

arxiv.org...

We report on the fabrication and use of deuterated polyethylene (dPE) as a coating material for ultra-cold neutron (UCN) storage and transport. The Fermi potential has been determined to be 214~neV and the wall loss coefficient η is 1.3⋅104 per wall collision. The coating technique allows for a wide range of applications and new possibilities in this field of physics. In particular, flexible and quasi-massless UCN guides with slit-less shutters and slit-less UCN storage volumes become possible. These properties enable the use in next-generation measurements of the electric dipole moment of the neutron.

It's funny that I read about this very recently as I had been doing personal research on zirconium diboride, and halfnium diboride... both of which have been eyed for use in reactors for their capacity to hold heat, more so the zirconium than the halfnium however.

My best guess would be they are using deuterated polyethene as a sort of binder around TRISO fuel pellets (micro pellets). The purpose for that would be to allow an automatic feed into a dense area to allow criticality to be reached, and then pulled out the other side once spent. All of this while remaining encapsulated, at lower masses due to the low levels of beta particle reflection.

a reply to: Zaphod58

good morning zaphod from the uk.

i'm unable to access the rfi data. could you throw me a truffle here?

regards f.

a reply to: Zaphod58

disregard my good fellow

2nd
f

a reply to: dubiousatworst

The TRISO fuel is supposedly still stable at 7800 degrees C.

There was an old Star Trek episode "For the World Is Hollow and I Have kissed the Sky".
Which got me thinking the ignition source might be some kind of Laser Interferometry Protocol.
In the episode Spock replaced an old style vacuum tube that had burned out leaving only 7 out of 8 to guide the alien vessel.

The Star Trek writers were just trying to initiate a paradigm shift for the flower children.

Early 1960's water cooled reactors would be just warming up at 180 degrees F, and similarly a Vacuum tube emitter operating at 2007 degrees F might not penetrate a zirconium diboride insulator to reach the collector screen(of an old style tube).

a reply to: Slichter

I was actually thinking the same thing about lasers after my previous post. Perhaps using them to excite the deuterated polyethylene, exciting it enough to disassociate the polyethylene, and thus introducing the deuterium to the TRISO fuel. Doing that would (could?) potentially mean a far smaller mass to reach criticality.

due to the shape and size of TRISO fuel pellets, there may not be a need for the old style tube, but rather a collection reservoir (for lack of better term) where criticallity is reached. Because of this, kind of set up I was thinking the laser excitation could take place before the TRISO embedded in deuterated Polyethylene "drops" into the critical density of fuel in the reservoir at the same time the disassociation occurs due to the heat generated. My thought process was that the zirconium diboride would be more of a vessel around the critical area rather than the tube set up of old.

The problem I have yet to to come up with a solution for (if anything I said would work in the first place) is how you evacuate only the spent fuel. Perhaps a raceway that over a set time releases it out of the bottom, allowing gravity to do the work, but using a raceway would mean that emergency evacuation of the reservoir would be a problem. Or perhaps there would never be a problem that needs an emergency evacuation due to the lack of pressure associated with such a setup, meaning that rather than having a hydrogen explosion in that case, it would "just" result in a hydrogen fire.

a reply to: dubiousatworst

Plasma physics is classified and a solution to the deuterated Polyethylene problem is probably more complex than a weed whacker.

Zap wanted us to take a look at applications that specifically use the TRISO fuel, and there are plenty of Google search links.
Satellites can't be cooled so they would be an obvious target for a fuel like TRISO.
The question might be better phrased "what is the government planning to do with people that have experience working with TRISO applications?"
Why use an RFI when they could just contact the labs that specialize in that?

originally posted by: Zaphod58

high-assay low enriched uranium (HALEU) advance gas reactor (AGR) tristructural isotropic (TRISO) fuel.

Interesting times.

Very interesting times indeed. Like zaph said. Read it very carefully. Some interesting clues.

a reply to: whywhynot

I thought Toshiba (??) had a small modular reactor running supercritical CO2 (SCO2) turbine to generate electricity. As a working fluid it is more efficient and smaller than steam. The reactor was like a smallish tool shed. The big plants do both steam and thermal as a method to increase efficiency. Even that lags behind SCO2.

I don’t recall what fuel the SMR ran but the design was like a compact pebble reactor (uranium coated in ceramics IIRC. On phone, drinking a beer!! Use at your own judgment! lol). I would personally like to see thorium used but last I read they were still doing fuel test in Norway (?? Thor Energy... beer!!)

As far as TRIOS goes, I thought all but Russia and maybe China have dropped fast neutron reactors (heat and components are in too harsh an environment but that is about to change). It has been around for years so maybe some secret high temperature ceramic is on the brink of released!

Interesting times indeed!!

a reply to: TEOTWAWKIAIFF

Kodak used to have a reactor.

Kodak's secret reactor.

Back in the 60's I heard they weren't going to do much more with nuclear power until the oil reserves started to dry up.
They are fracking shale and doing deep drilling which kicks the can further down the road.

They will probably test a Supercritical CO2-Brayton Cycle reactor with concentrated solar which is ~600 degrees Celsius.
I'm not sure what temperature the HALEU fuel reacts at safely and efficiently.
They don't need any more three mile island news.

The DOE's HALEU is from used fuel from the Experimental Breeder Reactor-II (EBR-II), which operated at the site from 1964 to 1994. Since 2000, DOE has employed an electrometallurgical treatment process at the MFC to refine and downblend the used high-enriched uranium fuel from the now-decommissioned reactor. About 10 tonnes of HALEU has been produced as a result of this process and is currently stored at INL.

originally posted by: Zaphod58
The FBO page has a rather interesting RFI posted on it. It calls for a reactor capable of up to 10 megawatts of power, using ambient air for cooling, that weighs less than 40 tons, can fit on a C-17, can run semi-autonomously for three years without refueling. The most interesting part is that it needs to be incapable of suffering a meltdown in various failure states.

Phase I will select up to three designs and complete detailed design work. Phase II will include materials purchase and prototype work. Selection is expected by Spring, dependent on information received from the RFI.

Small mobile reactor RFI

Part 1

Zaphod:

This is a very interesting post—thanks for sharing. I have been away from internet connectivity for a few days and unable to reply.

People who have posted here so far seem to be operating under some false beliefs/assumptions. I’ll try to respond to them in one post:

Slichter wrote:

“If they use a microfusion reactor for domestic power I guess they could afford the weight of two generators so one can be off line getting its deuterated polyethylene reloaded while the other powers the base.”

The reactors that are the subject of the RFI are nuclear fission reactors. They have nothing to do with fusion, micro or macro. There is no polyethylene involved.

“So if these units exist to power satellites they could be scaled to 10 megawatts.”

They don’t exist to power satellites. Most of the designs I’ve seen wouldn’t even work in zero G.

whywhynot wrote:

“After more reading I believe this is portable for transport but only intended to operate on land. I am unaware of any nuclear powered electrical generators that don’t use steam. Anyone understand differently please do tell.

Exactly. They are portable for transport but only intended to operate on land. Actually, probably buried.

It is true that most (if not all) existing civilian nuclear power plants use water as the primary working fluid circulating in the core. The fuel rod tubes are normally made out of Zirconium, so the primary loop can’t operate at a temperature above which the tubes start to chemically react with the water and produce Hydrogen (as in the Three Mile Island and Fukushima accidents). After leaving the core, the water is put through a heat exchanger where the secondary water loop is heated to create steam, which then goes through an expander to create shaft power and electricity. Because the core is primarily Aluminum the max working temperature inside the core is limited to about 650F. At that low of a temperature, extracting the power with a phase change fluid (liquid CO2 or H2O, for example) is pretty much the only practical way to do it.

But it doesn’t have to be that way. It is entirely possible to use a gas (Helium, usually) as the primary coolant circulating through the core. Reactors have been built this way and operated successfully. The most common use for gas cooled reactor cores is for breeder reactors, which are fast-spectrum reactors. However, there was a High Temperature Gas-cooled Reactor (HTGR) that was built and commercially operated at Fort St. Vrain, Colorado for about a decade. It used a combination of Uranium and Thorium for the fuel and achieved criticality on thermal nuetrons, not fast neutrons. Its fuel was held by graphite instead of Aluminum so it could operate at a higher temperature than water cooled reactors. The primary coolant was Helium which went into a heat exchanger to create steam. Because the resulting steam was hotter than usual, the thermal efficiency of the plant was quite high, compared to other, boiling water or pressurized water reactors.

It’s also possible to run the superheated Helium through a Helium-to-air heat exchanger and use the resulting hot air as either process heat and/or to produce shaft power. In that case, a Brayton cycle (gas turbine) would probably be used, since they don’t have to cool the exhaust gas—they simply use the atmosphere as a big heat sink. The old Nuclear Energy for Propulsion of Aircraft (NEPA) program of the late 1940s used this approach; they put the reactor heat through a heat exchanger to power some J47 jet engines. I suspect that these SCO reactors will use Brayton cycle expanders so that they can be located free of any cooling water requirements.

Part 2

whywhynot also wrote:

“I think this just another huge waste of our tax dollars. If they want to do R&D work on something with a closer event horizon.”

This is not R&D. The SCO is calling for companies to put in bids for reactor designs that can be designed and built quickly. TRISO fuel was invented in England and was demonstrated in one of their HTGRs (the “Dragon”reactor) as long ago as 1976. In recent years, the US DOE built and qualified their own version of this fuel. The event horizon of this project is about 2025, IIRC. China seems to be ahead of everyone else on this reactor technology and I believe this RFI is part of Mike Griffin’s plan to catch up and surpass.

Dasman888 wrote:

"There are much safer and better ways to generate nuclear power…like pebble bed reactors and especially thorium salt reactors..both of which have been designed in a manner that by definition, are incapable of going critical.”

The TRISO fueled reactors that China is developing are pebble bed reactors. I strongly suspect that most of the designs that come in as a response to this RFI will also be pebble bed reactors. However, TRISO fuel is also compatible with molten salt designs. Once a nation establishes a commercial supply line for TRISO fuel, it could and probably would develop both options.

All fission reactors, by definition, MUST be able to go critical; that is the basis of a self sustaining chain reaction. I think you mean that pebble bed and molten salt reactors can’t melt down, and that is true. You can run TRISO fuel at its full power, shut the reactor down and immediately stop its cooling loop, and the fuel will not melt and release its nasty radionuclides.

DigginFoTroof wrote:

“Does anyone know why they are planning to use 5-20% enriched uranium?”

Going to higher enrichment levels in a reactor produces two advantages. First, it results in a smaller diameter core. That results in smaller containment vessels and an overall smaller reactor system. Smaller usually means cheaper in the commercial realm. Second, it results in longer lifetime of the fuel in the core, higher burnup rates, and overall more efficient use of fissile materials (Uranium/Thorium). The spent fuel doesn’t have to be continuously swapped out all the time. That’s why the Navy uses HEU in their reactors. Even though these SCO reactors won’t use HEU, they will use High Assay Low Enriched Uranium (HALEU). Current commercial reactors use fuel enriched to less than 5%, and that is the highest enrichment level that US industry is set up to deliver. Once you get to an enrichment level of 20%, Special Nuclear Material (SNM) is considered well on its way to being weapons grade. SNM enriched to just below 20% is the highest concentration that can be used without having to be treated as weapons grade. If these small SCO reactors had to treat all their fuel with the same security processes as used for nuclear weapons, it would be totally impractical to think about widespread use of them.

and:

“I wouldn’t put it past the people who wrote the RGI to either be unaware of aspects of nuclear energy or even the complete intended use of the reactor.”

Nope. Not even close. This RFI was put out by the Strategic Capabilites Office of the DOD. The SCO is now being run by Chris Shank, who was put in that position by Mike Griffin, who is now the Under Secretary of Defense for Research and Engineering. I worked on special assignment with them back when Mike was NASA administrator and Chris was his special assistant. I was part a team that analyzed NASA’s surface nuclear power program (for use on Lunar and Mars bases) and made recommendations about NASA’s investment policy for that program. Mike goes back with nuclear systems even further than that, when he was head of the SDIO technology program and they were developing Timber Wind and also extracting the Russian TOPAZ reactor technology from the recently collapsed Soviet Union. This is not their first rodeo with nuclear systems. This looks like it’s a part of Mike’s self-proclaimed campaign to quickly improve the US position on strategic systems with regard to our major international adversaries.

Dubiousatworst wrote:

“My best guess would be they are using deuterated polyethylene as a sort of binder around the TRISO fuel pellets…The purpose would be to allow an automatic feed into a dense area to allow criticality to be reached, and then pulled out the other side once spent. All of this while remaining encapsulated, at lower masses due to the lower levels of beta particle reflection.”

I repeat: there is NO polyethylene associated with TRISO fuel; it could not even begin to survive in the high temperature environment of an HGTR. Also, there is absolutely no function for deuterium in a fission reactor. Also, beta particle reflection has nothing to do with fission reactors. I suspect you are confusing fusion reactors and fission reactors.

TEOTWAWKIAIFF WROTE:
“As far as TRISO goes, I thought all but Russia and maybe China have dropped fast neutron reactors…”

The development and use of TRISO fuel has nothing to do with fast neutron reactors. All the SCO reactors using TRISO will go critical on thermal neutrons.
a reply to: Zaphod58

a reply to: 1947boomer

What really surprised more than one person was the name that was left in. It's got to be an unofficial name as it wasn't found anywhere else that was searched. But interesting still.

My mistake was of what deuterium contained I was thinking it could possibly be used to provide a more neutron dense material making it easier to cascade and thus easier to maintain criticality in a fission reaction.

Also the thought of polyethylene is not to stand the heat, and that was specifically being used in my thought as a feature due to it being a thermoplastic. As it as a carrier would melt away allowing the TRISO pellets to be closer to one another while keeping them further apart for transport as the thought was that the TRISO pellets would be embedded in a thin rope and as introduced it would melt away purposefully.

Im sure I am wrong for a number of reasons, and I thank you for posting information, I always want to learn more.