This topic contains 3 replies, has 3 voices, and was last updated by Retrocosm 3 weeks ago.
October 29, 2019 at 2:07 pm #106313Member
- Hitting The Trail
I thought this may be of some vague interest to someone on here…
So, I just recently watch HBO’s Chernobyl, 3 or 4 times… And it turns out, RBMK reactors are interesting, and there is actually some information out there about how they work and how they’re made, including dimensions for the the fuel rods and now infamous graphite moderator block… I’m sure the Wikipedia article is 100% accurate…
While I was reading up on it, it occoured to me that a display model of a fuel rod would be an excellent addition to my desk…
First thing I did was make a 1/20th scale version. I used a piece of stainless for the rod and aluminium square painted black for the graphite.
I don’t think this is 100% accurate to the design, but it looks cool…
Onto a more detailed 1/10th scale version…
I found this diagram on Wikipedia but I think falsely assumed it was all housed in a tube. Technically it is, the fuel bundle sits in a channel where water is pumped, the fuel turns it to steam and it carries onto the turbines to create power, however… The channel is part of the reactor, not the fuel bundle, but I wanted to have a cutaway showing the rods inside the channel so I stuck with my original idea, how many people actually know what they look like anyway? They’ll kill you if you get too close…
So, dimensions are as follows: graphite blocks are 250mm square and range something like 200-600mm long, so 25mm square aluminium is perfect 1/10th scale. The hole through the block is 114mm, closest I could come up with is 12mm, close enough since we’re not actually doing nuclear physics here.
I didn’t get any pictures of the machining (I need to get better at that) but it’s all fairly simple, use a 4 jaw to chuck the square bar in the lathe and machine the blocks spigot and drill the hole. Turned both bits of the main tubing out of solid mystery steel, the larger one has a 10mm hole 100mm deep, which was a little stressful… The internal rods are just 2mm drill rod stock cut to length and the spacers are brass, drill manually. The window in the tube was milled out carefully, I definitely didn’t get one of my largest, most expensive end mills glowing the first time I tried, promise…
My favourite part, the ‘mini’ gun
Getting that assembly inside the tube took a minute, lots of very light filling and twisting, probably shouldn’t make my tolerances so tight when this has absolutely no mechanical purpose at all…
The thing with nuclear fuel bundles, is that they get hot… Very hot, and most metals change colour at high temps, its an oxide layer that forms and filters light, giving a specific colour. Now, I’m not sure what the properties of zirconium alloy are (which is what real ones are made of) but I do know they’re operated in an oxygen free environment, which means probably no oxidisation… But I think as a display piece it has to look like its been warm, so I gave the parts a bit of heat to see what colour this mystery steel likes to go, and I’m super glad I did.
Starting to look like something now…
Next up was the top piece, the assembly that the fuel crane uses to insert or remove the rod. I was very lucky to find a YouTube video of a guided tour of one of Chernobyl’s other reactors, which despite being shut down and in the process of decommission, still had a large stock of fuel bundle carriers, also called stringers. Basically just the central rod with the crane attachment. This gave me some great reference material to work with, just no dimensions.
So I decided to make a rod out of stainless, make the crane attachment out of brass and sleeve it with another piece of steel, like this.
Next up was painting the block. I sprayed it matt black then ground up a graphite crayon and rubbed it into the surface. A great technique for making things look metallic too.
That should be a GIF showing the difference between the paint and graphite, not sure if it’s worked though.
Now the model itself is finished, it needed displaying and I though I’d try and make it as 80’s in the Soviet union as possible with some Soviet-ly chamfered aluminium supports and a nice piece of hardwood.
I gave the supports a stonewashed finish by literally washing them in stones… Basically I put the parts, gravel and polishing compound into a jar and stuck the jar in the lathe for an hour.
Gave the wood an oil and I’m calling it done, except the block needs another coat of graphite after all the handling putting it together.
Once I redo the block I’ll get some better photos.
Again, it’s not super accurate given the whole tube arrangement but it’s a nice desk piece and conversation starter. Over all pretty happy with it, not great, not terrible…
Hopefully that was interesting to someone, or maybe nuclear reactor design is as boring as everyone keeps telling me…October 29, 2019 at 2:39 pm #106314Member
- Hitting The Trail
Gif didn’t work so here it is http://imgur.com/a/0oemii7October 30, 2019 at 8:51 am #106316Member
- Scale Off Road Pro
My missus watched that program – I couldn’t; I’ve got soft in my old age and when I expose myself to the horrors of this world it just depresses me. The part with the children dancing in the fallout on the ‘murder bridge’ or whatever they called it, was just so sad.
What a great little project though, I admire your obvious fascination with the subject and you got an awesome result!
Axial SCX10 Dingo D90 RC4WD TF2 Hilux RC4WD G2 D90October 30, 2019 at 9:35 am #106317Sysop
- Scale Off Road Pro
Very cool, love the idea. I’ve been obsessed with this topic for years reading and watching everything I could find about it and enjoyed the series. There was a great documentary on a couple of years ago about the new containtment building which is an extraordinary engineering achievement.
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