Nuclear trains

OVERKILL

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Besides the other obvious safety concerns with putting a nuclear reactor in a train, there is one overriding concern that can be described in two words... Terrorist Target (a VERY attractive terrorist target). Imagine what would happen if a truck packed with explosives was run into the side of one of these trains in downtown Chicago.
It would be designed so that nothing would happen. Again, you make it a passively cooled reactor where the entire unit is inside robust containment.

Basically, take something like the MMR design (helium cooled), make it even smaller so its passive safety can be the actual containment structure, and further ruggedize it for this type of usage scenario:
Screen Shot 2022-10-10 at 1.49.54 PM.png


From here: https://www.usnc.com/assets/media-k...chnical Information Document.pdf?v=4287b35212

Now, that unit is 5MWe (15MWth), which is ~6,700HP (20,000HP). Your typical diesel locomotive is 3-5,000HP and size would clearly be a design issue due to containment requirements:
Screen Shot 2022-10-10 at 1.54.58 PM.png


But, it's technologically possible.

Now, is it financially viable? That's a very separate discussion and I'd argue, with the state of the US nuclear industry, no, it would be VERY difficult to make a financial case for something like this.

Highly recommend watching some of these tests for used fuel casks:



IAEA transport of spent nuclear fuel:


You'll note that we already transport this stuff by rail, road, ship and aircraft.
 

OVERKILL

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Grid-powered electric trains are a mature technology that has been used for many decades. Overhead wires are preferred for long distance electric rail lines since they can operate at a higher voltage than a third rail and achieve more efficiency. It's difficult to touch the live wires by accident. Third rail systems are used in urban areas since it is more compact and aesthetic.
My understanding of the development for the Soviets and then later Russians, was for remote service routes. Similar to how they have a nuclear barge currently powering and heating a town in Siberia. While for short haul and local routes electrified rail (and trams) is clearly the most logical route (and I'm talking to my town council candidates about bringing back our local trams) the issue is for long hauls with expansive countries like the US, Canada, Russia...etc. This is where, in theory, something like this would make sense as a decarbonization effort.
 

OVERKILL

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I know I've mentioned this before how in my ideal world we'd have a plug-n-play power source for our homes rathe than having to rely on a utility.

Are there any technical challenges to using a self regulating nuke to power ones home? I'm thinking of something about the size of a large piece of luggage.
Technical? Not really. It's more of a cost issue. We are seeing these developments with things like the USNC MMR, but these are still "big" units compared to what you are describing. It will be interesting to see how effective (and cost effective) these end up being, IF they succeed, and that's a BIG IF, then potentially we'll start seeing smaller units developed for powering warehouses and places that currently use cogen and eventually that could trickle down to residential units.
 

OVERKILL

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People aren't goint to go for nuclear reactors running down the tracks. There is quite the fear of derailments of hazardous materials as it is.
Yes, that would be one of the biggest issues, social license and societal acceptance, which is likely while we'll never see it come to be, despite it technically being viable.

We are far more likely to see nuclear powered shipping, since that application is already proven with a phenomenal track record for safety and reliability.
 
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Interesting concept, likely going to work only in remote area with minimal cleanup need if things hit the fan, but hard to provide all the support for traditional steam and diesel trains.

Probably also a good rail based power source for rural area too, if you transport stuff remotely and need power source to process them, load and unload, etc, this train could actually be self-powering a community. It would be very useful for seasonal power need.

Put the engine in the middle of the train if you are concerned about crashing or derail.
 

OVERKILL

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Not to mention that nuclear powered ships are self-insured (owned by a Sovereign). Insurance, refueling/waste removal, terrorists targets are major issues. Perhaps one day.
Yes, some definite challenges. I think the Savanah was owned by the US government? Sevmorput is owned by Rosatom, which in turn is a state-owned company.
 
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There were many rail systems with overhead wires, too. It was probably more economical to use diesel-electric for long haul though. No poles and wires infrastucture, no worries about local/regional outages stopping trains in their tracks.
Every diesel electric could be run with the diesel engine off if a mechanism to affix grid power were developed.

AKA it could run on electric in areas with infrastructure and switch to diesel when it isn’t

Every normal train has a full electric drivetrain so it’s not a stretch
 
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This thread is a tangent from a bit of a comedic remark I made in another thread talking about steam locomotives, but the reality is that this has been looked at by both the US and the Soviets (and more recently the Russians, via Rosatom, the company that produced the SMR barge that's powering a town in Siberia and runs the only nuclear powered freighter).

These are from an old Life magazine:
View attachment 120397
View attachment 120398
View attachment 120399

The Rosatom design used a breeder:



Of course, I've heard nothing about this since, and this was 11 years ago, so the odds are that it wasn't as easy to bring into production as assumed (not surprising). Of course with the war in the Ukraine, Rosatom is now toxic and the export aspirations are either on the ropes with potential clients or soundly torpedoed. An unfortunate situation for an extremely innovative company.

Conceptually of course, the idea of a nuclear-powered locomotive is quite logical. Nuclear reactors are an evolutionary step for anything that has used steam or electricity. This is easy to follow with their use in submarines, aircraft carriers, ice breakers, freighters and of course power plants. Being on land and operating in civilian space with the high likelihood of collision, of course locomotive use would require robust containment and a design that could not melt down in the event of an accident. This isn't much of an issue for ocean-going vessels, since they are surrounded by the world's largest heat sink, but it would certain pose some technical challenges for something land based.
Coincidentally enough, earlier this year I was skimming through some of the LIFE magazines Google has archived, and saw this article. 1954?
 

UncleDave

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Do you have any engineering or design insight you'd like to share as to why you feel this is the case?

I will note that, as executed, the nuclear jet engine idea was horrifying, however, the idea of running a locomotive doesn't differ much from running a sub, of which there have been hundreds of examples.

I was going to say the same thing regarding the train - not a whole lot different from a submarine on several levels.

Still a nuke plant and a completely electrified rail system feels safer. A Diesel is really a diesel electric anyway.
 
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twouvakind

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Every diesel electric could be run with the diesel engine off if a mechanism to affix grid power were developed.

AKA it could run on electric in areas with infrastructure and switch to diesel when it isn’t

Every normal train has a full electric drivetrain so it’s not a stretch
New Jersey Transit has been running these dual mode locomotives for a few years now. They use marine diesels and are not very efficient in diesel mode. NJT has many miles of non electrified territory that connects with the Northeast corridor (overhead catenary). Their objective was to give passengers a "one seat ride" into NYP and not have to change trains. Due to physical capacity issues with NYP this one seat ride thing only works off-peak (weekends etc) Changing trains is still a necessary evil in and out of New York on several routes. Image show unit in diesel mode with it's singular pantograph down.
Screenshot_20221202-212521.jpg
 
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Every diesel electric could be run with the diesel engine off if a mechanism to affix grid power were developed.

AKA it could run on electric in areas with infrastructure and switch to diesel when it isn’t

Every normal train has a full electric drivetrain so it’s not a stretch

Siemens offers their Vectron electric locomotives also as "Dual Mode" variants. I.e. a small diesel generator is added to the electric locomotive to allow a train to run on shorter branch lines at lower speed and to be able to perform shunting duties at the customer. Diesel power is either 950kW or 2000kW, electric is 2.4MW. Compared to the "full" electric locomotive who are available with power from 5.2 to 6.4 MW, the dual modes are considerably less powerful, but for leight freight duty that is still enough.



Stadler offer the Eurodual, as six-axle freight locomotive. 7MW electric power, 2.8MW Diesel, so this one can replace a "real" diesel locomotive also on unelectrified mainlines.
Unlike the Vectrons family, which contain variants for top speeds of up to 230km/h, the Eurodual, being freight-focused, are limited to only 120 - 160km/h (depending on gearing). (Vectron Dual-Mode though seem to be limited to 160km/h, too.)





Euroduals have quickly become very popular by private rail companies who focus on running heavy bulk cargo trains to or from "remote" customers situated at un-electrified branch lines. Because of the significant fuel savings (and significantly higher power when operating under catenary), they are now killing off Class 66/77 heavy diesels which were popular in this role due to their primitive design (they're basically SD-somethings dressed in british outfit) and thus low maintenance costs and the soviet-built TЭ109 "Ludmilla".
 
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There were many rail systems with overhead wires, too. It was probably more economical to use diesel-electric for long haul though. No poles and wires infrastucture, no worries about local/regional outages stopping trains in their tracks.

The track has to be used regularly to keep the rails rust free. Over here, if a track hasn't been used for 24 hours, a diesel ocomotive is run over it first to remove oxidation, before electric trains can go.
 
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I can only imagine this being an issue with low voltages. Which voltage does the railways use in your area? 15kV or 25kV AC should not care much about a fraction of a millimeter of rust...

(Another possibility might be that axle-sensing may be impaired by surface rust, that is if your safety systems do not use wheel counters, but apply an electric current to the rails to detect if there is something in the block... Then I can imagine how regulation could demand that visually "clear" the section of track after an interruption of service before running trains at regular speed.)


Edit: obviously, electrifying rarely used branch lines that only see a train once a week makes no sense economically, so nobody would do that anyways.
 

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Do you have any engineering or design insight you'd like to share as to why you feel this is the case?

I will note that, as executed, the nuclear jet engine idea was horrifying, however, the idea of running a locomotive doesn't differ much from running a sub, of which there have been hundreds of examples.

You can tow a sub out and sink it. Not only is the ocean a great heat sink for cooling fresh water through heat exchangers, it also passively cools the hull and can be used for emergency cooling.

The ocean also provides great shielding.

I feel like the cost (and space and weight) of shielding, makeup water stores, maintenance, and crew training would be prohibitive. That’s even if you can get passed the, “not in my backyard!!!” crowd.

Edit: if you can’t safely have someone walk up and touch the RC without getting dosed (ie, rad levels less than background), I think it will be a non-starter. No one is going to see the nuclear postings and exclusion zone warnings and think, “thats probably fine”.
 
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