from Hacker News

How the first fourth-generation nuclear power plant works

by chris222 on 1/7/24, 5:50 PM with 103 comments

• by hunglee2 on 1/7/24, 6:29 PM

  Exciting to see this - so many advantages to pebble bed nuclear reactors including inherent safety (no risk of meltdown), use of helium coolant, ease of waste recycling disposal and continuous refuelling by simply adding more pebbles to the hopper.

  Illinois Energy Prof has an excellent YT channel on energy, and has a great talk on IV gen reactor design. Saw it 4 years ago, so pumped to see some of the ideas he was talking about get plugged into the grid

  https://www.youtube.com/watch?v=_mJ3S-VQuHY&t=490s for those who want to know more

• by acidburnNSA on 1/7/24, 7:24 PM

  Glad they got a high temperature gas cooled reactor up and running!

  I do dislike the terminology/categorization around 'fourth generation'. The first ever proposed commercial reactor (the Daniels Pile) was a pebble bed gas cooled reactor concept, worked on at Oak Ridge in the 1940s. We've built lots of gas-cooled reactors in the past, including helium cooled ones. Such as:

  * Peach Bottom

  * Fort St. Vrain

  * HTTR

  * Dragon

  * HTR-10

  * AVR pebble bed

  * THTR-300

  * Ultra-High Temperature Reactor Experiment (UHTREX)

  Nitrogen-cooled ones, such as ML-1 and GCRE

  CO2-cooled ones, like EL4, Lucens, AGR, Magnox

  Air-cooled ones like HTRE

  Liquid-hydrogen cooled ones like NERVA

  It's kinda dumb to call this the first 4-th gen reactor.

• by photochemsyn on 1/7/24, 8:15 PM

  Better article here:

  https://www.world-nuclear-news.org/Articles/Chinese-HTR-PM-D...

  > "The HTR-PM features two small reactors (each of 250 MWt) that drive a single 210 MWe steam turbine. It uses helium as coolant and graphite as the moderator. Each reactor is loaded with more than 400,000 spherical fuel elements (‘pebbles’), each 60 mm in diameter and containing 7 g of fuel enriched to 8.5%. Each pebble has an outer layer of graphite and contains some 12,000 four-layer ceramic-coated fuel particles dispersed in a graphite matrix."

  Note that Chernobyl was graphite-moderated and water-cooled, but hot graphite and steam is a bad combination, tending towards the generation of (explosive) hydrogen and carbon monooxide gases during loss-of-coolant type accidents. The helium coolant avoids this process, and can sustain higher operating temperatures so has industrial uses, somewhat ironically in the petrochemical sector:

  > "The major purpose of HTR-PM is to co-generate high temperature steam up to 500℃ and electricity. It is cost effective currently in the Chinese market to supply steam and electricity for the petrochemical industry to substitute the burning of natural gas and coal."

  It seems like a pretty safe design with some unique capabilities, although it'd be interesting to see the total cost-per-pellet inputs (each 6 cm pellet generates as much power as 1.5 tons of coal prior to its retirement, but manufacturing each pellet is probably not that cheap).

• by pfdietz on 1/7/24, 7:31 PM

  A significant advantage of a higher temperature reactor would be if it could use the same steam turbines used in combined cycle plants. These are "dry" turbines that operate with high temperature (550 C) steam. In contrast, LWRs use "wet" turbines with saturated steam at temperature a couple of hundred degrees lower. They're about the only ones still doing so, I think, so the turbines are bespoke and do not benefit from the economies of scale of the CC steam turbines.

  (550 C is the upper temperature limit for cheap steel against creep, so I think that choice of temperature is not a coincidence. It also makes me dubious of reactor concepts operating at higher temperature.)

• by Almondsetat on 1/7/24, 7:57 PM

  Doesn't China building so many civilian reactors mean they are getting more experience and more specialized workforce in nuclear energy than anyone else? How can the west compete if most nations reject the atom and the ones who don't either have minuscule numbers or focus more on military reactors?

• by lven on 1/7/24, 11:43 PM

  My own partisan comments on the pebble bed class of reactors (https://lvenneri.com/blog/pebble-bed-nukegumball) for those interested in a deeper yet still qualitative comparison of pebble beds and prismatic cores - the main types high temperature reactor. Long story short : pebbles offer significant disadvantages compared to prismatic geometries, summarized by this donald duck clip: https://youtu.be/shvwSBGDmE0.

• by DarkNova6 on 1/7/24, 10:46 PM

  This reads more as a puff piece than an informative article. Hardly surprised coming from the "China Global Television Network". It just reads like "Everything going great, look no further".

  And for somebody who has been following the development of 4th generation reactors, this one is rather non-exciting. Yes it uses a pebble-bed and higher temperature (hence VHTR), it's overall improvements are rather diminishing compared to Gen 3 designs. The meager output of 150m isn't exactly thrilling and the possibility for hydrogen production remains unused as well.

  I don't want to be purely cynical. Every incremental advance is a form progression and can advance the status-quo as we know. But the most promising space is clearly happening in the Fast Reactor space, just maybe not the SFR, this is a nuclear disaster waiting to happen.

• by p1mrx on 1/7/24, 7:02 PM

  China's HTR-PM (the topic of this article) is similar to the Xe-100 that X-energy is planning to build in Texas:

  https://x-energy.com/seadrift

  But they've yet to apply for NRC approval, so who knows if that'll actually happen.

• by vlovich123 on 1/7/24, 7:12 PM

  China has also started experimenting building commercial molten salt reactors so it'll be interesting what the fourth generation power plant shootout will look like.

• by ziofill on 1/7/24, 8:24 PM

  > The operating reactors are cooled by the inert gas helium instead of water.

  Is this going to hit a wall when scaling up? Helium is notoriously scarcer lately https://www.innovationnewsnetwork.com/helium-shortage-4-0-wh...

• by brazzy on 1/7/24, 7:50 PM

  Unfortunately the "how it works" is very shallow, the Wikipedia article has a lot more meat: https://en.wikipedia.org/wiki/Pebble-bed_reactor

• by SnorkelTan on 1/7/24, 6:59 PM

  Article text covered by obnoxious banner in firefox. Anyone got a link to the text?

• by knlje on 1/7/24, 8:52 PM

  According to this summary, Germany has lots of remaining problems with its prototype pebble bed reactors: https://web.archive.org/web/20170329044120/http://nuris.org/...

• by hmm37 on 1/8/24, 12:10 AM

  What's interesting is whether this tech will allow China to replace their coal plant boilers with this one as a drop-in.

  e.g. https://www.nextbigfuture.com/2016/12/chinas-plans-to-begin-...

• by euroderf on 1/7/24, 8:29 PM

  As I've understood it, the main risk of running a PBMR is that putting out a graphite fire is somewhere between very difficult and impossible. Does this particular design somehow address this ?

• by jansan on 1/7/24, 7:30 PM

  Reading this as a German feels really bitter. Our government has cancelled ALL research into nuclear reactors. We are completely out of the race, and there is probably no way back.

• by mvac on 1/7/24, 9:49 PM

  Thiel was right (9y ago) with the west being leader in innovation in the world of bits, but not in the world of atoms.

• by nuclearsugar on 1/8/24, 6:49 PM

  Is the helium cooling aspect part of a closed system?

• by huytersd on 1/7/24, 8:45 PM

  So it sounds like all new things (that aren’t an idea or software) will come from China moving forward. I hate this but it’s interesting in a way to see how far they will get. The US supercharged the world for generations but now seems to have directed all its attention to feminizing its men. I wonder how far the Chinese can take it. Settlement on the moon? Mars? Generational ships headed out of the solar system? Anything seems possible with the mostly benevolent dictatorship they have going on over there.

• by einpoklum on 1/7/24, 8:26 PM

  Shell script wrapper invoking a third-generation nuclear power plant?

  Ah, no, it's a physicists' project, so maybe a fortran90 program invoking a fortran77 program? Am I close?