5 ms·

It's a liquid-sodium-cooled, graphite-core system with no need for pumps, aka 'passively cooled' via heat [edit] pipes. Output is: > "The microreactor can gene

It's a liquid-sodium-cooled, graphite-core system with no need for pumps, aka 'passively cooled' via heat [edit] pipes. Output is: > "The microreactor can generate 5 MW of electricity or 13 MW of heat from a 15 MW thermal core. Exhaust heat from the power conversion system can be used for district heating applications or low-temperature steam." Control systems are kind of interesting: > "The only moving or mechanical parts in the reactor system are reactivity control drums, which manage the power level and allow absorber material to passively turn inward toward the core if power demand is reduced or lost, and turn a reflector material toward the core if demand increases automatically. Hence the term “nuclear battery.”" I'm generally not a nuclear advocate but if they've really managed to eliminate the need for active cooling, and have a robust system that can safely shut down with concerns about meltdown even without external power, that's a pretty big advance. Looks remarkably promising... keep your fingers crossed. (New nuclear tech hasn't had the greatest track record over the past several decades, i.e. pebble beds didn't work out etc.)

DiggyJohnson 4y ago
Not trying to be a pedant, but I think you might have a typo in the core of your point: > …, and have a robust system that can safely shut down with concern about meltdown Do you mean ‘without’?
- FrostKiwi 4y ago
  I think it's 'with', as in 'regarding'. "With the rising concerns around orange peel ethics, we put focus on creating a humane peeling device for fruits."
  - largbae 4y ago
    I am intrigued by this concept and would like to learn more!
- photochemsyn 4y ago
  oops left out a 'no' between with and concern.
Accujack 4y ago
It uses TRISO fuel, which are fissionable materials enclosed in a carbon and ceramic shell that's extremely tough and can handle far higher temperatures than are present in a reactor without melting. The shell prevents the release of radioactive materials, so TRISO fuel encapsulation would turn a melt down into a reactor damaging event rather than an emergency/crisis. A runaway reactor would get hot, melt its structure, and maybe drop parts inside its containment, but the fuel wouldn't melt and wouldn't travel far. Most likely the reaction would stop as soon as the structure of the core fell apart.
- nine_k 4y ago
  I wonder if that fuel is usable in a breeder after it's "spent". Usually "spent fuel" has spent a few percent of the usable fissionable material, but the products of decay (and partly synthesis) prevent it from working efficiently.
- consumer451 4y ago
  > It uses TRISO fuel, which are fissionable materials enclosed in a carbon and ceramic shell that's extremely tough and can handle far higher temperatures than are present in a reactor without melting. I was going to make a top level comment along the lines of: "How thick/expensive a bunker would one need to build around one of these to prevent it from spreading radioactive materials about when hit by say, an airplane? As I understand it, large legacy reactors are hardened for this. Would the same level of safety still allow these smaller reactors to be economically viable?" But now that I have read your comment, would a kinetic event happening to a TRISO fueled reactor be more of a non-event? Follow up, would non-fuel components of the reactor become radioactive over time as well? Sorry if dumb questions, not very educated in this space.
  - bell-cot 4y ago
    For small reactors, with minimal requirements for support equipment and ~no need for active cooling during emergency shutdown, the design trend I've seen is "put it underground". Which makes sense - bomb shelters, military bunkers, etc. have been put underground for centuries because that's a relatively quick & cheap way to make something that's very hard to destroy.
this_steve_j 4y ago
It’s good to see the designers absorbed a dose of inspiration from the pioneering excursions in US sodium reactors. Mechanical coolant pumps were the Achilles heel of the infamous Sodium Reactor Experiment (SRE) from 1957-64 at Santa Susana field laboratory. It had 50,000 lbs of liquid sodium in two coolant loops. When 4 pints of tetralin leaked from a pump seal into molten sodium surrounding the SRE reactor core (500-950F), it fouled the fuel cladding with “brown stuff” and various fission products from the melted rods were found on both sides of the fence. [1] A “small amount of sodium” in sealed heat pipes sounds pretty safe. But since Westinghouse filed all the eVinci’s NRC pre-application materials as “proprietary”, the actual design details aren’t available to the public for review. “Disruption” I assume refers to hundreds of rule exemptions (licensing innovations) they filed as a non-LWR. Not judging, just stating the record. [2] 1. https://www.etec.energy.gov/Library/Main/Doc._No._1_SRE_Fuel_Element_Damage_Interim%20Report_11.15.1959_NAA-SR-4488.pdf https://www.etec.energy.gov/Library/Main/Doc._No._1_SRE_Fuel... 2. https://www.nrc.gov/reactors/new-reactors/advanced/licensing-activities/pre-application-activities/evinci.html https://www.nrc.gov/reactors/new-reactors/advanced/licensing...
rob74 4y ago
> Westinghouse looks to off-grid applications like remote communities and mine sites as the entry market for eVinci. Yeah, install a nuclear reactor at a remote mining site, probably without sufficiently trained personnel to take care of it. What could go wrong?
- function_seven 4y ago
  Why would you assume untrained personnel? These would still be regulated by the DoE.
  - jimnotgym 4y ago
    What about security? In the UK nuclear installations are under 24/7 armed guard from a special police force. That would be expensive to maintain in a remote region, although I guess they already have security at diamond mines, or instance
    - tecleandor 4y ago
      I guess that comparing it to the cost of setting up a super long power line and maintaining it (sabotages, fires, whatever), maybe it's interesting.
    - inglor_cz 4y ago
      Vastness of rural US is a security factor on its own. Plenty of military installations in the desert aren't even fenced.
      - Swenrekcah 4y ago
        They’re perhaps not fenced but presumably they’re full of armed military personnel?
        bell-cot 4y ago
        You've never really been out in the American West, have you? Just one example - the Nevada Test and Training Range alone is a bit over 4,500 square miles. https://en.m.wikipedia.org/wiki/Nevada_Test_and_Training_Range https://en.m.wikipedia.org/wiki/Nevada_Test_and_Training_Ran... Vs. Wikipedia says the entire U.S. Army (active duty) has ~485,000 personnel. Divide...and that's ~0.17 Army people per acre, even if the US Army had NO job except holding down the NTTR. (Which is actually US Air Force, BTW.) [Edit: But +1 - because in the bigger picture you make a valid point. However vast the open spaces, at the spots where the cool & expensive stuff sits, there does have to be some sort of "real" security. If only so dodgy locals don't swing by with a pair of bolt cutters, and start helping themselves.]
UltraViolence 4y ago
Until an explosion damages the heat-pipes and you get a runaway meltdown and explosion of the core after hydrogen gas builds up. Very realistic scenario if the thing is used in a war zone.
- nebopolis 4y ago
  Being sodium cooled, both a steam explosion and hydrogen gas generation via water is ac minimized. Lots of safety advantages to a coolant that is still liquid at operating core temperature with no added pressure. But of course liquid sodium does come with some other caveats that are of concern. Making it a sealed unit with minimum moving parts helps with some of those potential problems for sure. As does keeping the total thermal capacity relatively low, below the threshold where secondary fission products need active cooling to prevent meltdown even after the reactor is shutdown.

DiggyJohnson 4y ago

Not trying to be a pedant, but I think you might have a typo in the core of your point: > …, and have a robust system that can safely shut down with concern about meltdown Do you mean ‘without’?

FrostKiwi 4y ago
I think it's 'with', as in 'regarding'. "With the rising concerns around orange peel ethics, we put focus on creating a humane peeling device for fruits."
- largbae 4y ago
  I am intrigued by this concept and would like to learn more!
photochemsyn 4y ago
oops left out a 'no' between with and concern.

Accujack 4y ago

It uses TRISO fuel, which are fissionable materials enclosed in a carbon and ceramic shell that's extremely tough and can handle far higher temperatures than are present in a reactor without melting. The shell prevents the release of radioactive materials, so TRISO fuel encapsulation would turn a melt down into a reactor damaging event rather than an emergency/crisis. A runaway reactor would get hot, melt its structure, and maybe drop parts inside its containment, but the fuel wouldn't melt and wouldn't travel far. Most likely the reaction would stop as soon as the structure of the core fell apart.

nine_k 4y ago
I wonder if that fuel is usable in a breeder after it's "spent". Usually "spent fuel" has spent a few percent of the usable fissionable material, but the products of decay (and partly synthesis) prevent it from working efficiently.
consumer451 4y ago
> It uses TRISO fuel, which are fissionable materials enclosed in a carbon and ceramic shell that's extremely tough and can handle far higher temperatures than are present in a reactor without melting. I was going to make a top level comment along the lines of: "How thick/expensive a bunker would one need to build around one of these to prevent it from spreading radioactive materials about when hit by say, an airplane? As I understand it, large legacy reactors are hardened for this. Would the same level of safety still allow these smaller reactors to be economically viable?" But now that I have read your comment, would a kinetic event happening to a TRISO fueled reactor be more of a non-event? Follow up, would non-fuel components of the reactor become radioactive over time as well? Sorry if dumb questions, not very educated in this space.
- bell-cot 4y ago
  For small reactors, with minimal requirements for support equipment and ~no need for active cooling during emergency shutdown, the design trend I've seen is "put it underground". Which makes sense - bomb shelters, military bunkers, etc. have been put underground for centuries because that's a relatively quick & cheap way to make something that's very hard to destroy.

this_steve_j 4y ago

It’s good to see the designers absorbed a dose of inspiration from the pioneering excursions in US sodium reactors. Mechanical coolant pumps were the Achilles heel of the infamous Sodium Reactor Experiment (SRE) from 1957-64 at Santa Susana field laboratory. It had 50,000 lbs of liquid sodium in two coolant loops. When 4 pints of tetralin leaked from a pump seal into molten sodium surrounding the SRE reactor core (500-950F), it fouled the fuel cladding with “brown stuff” and various fission products from the melted rods were found on both sides of the fence. [1] A “small amount of sodium” in sealed heat pipes sounds pretty safe. But since Westinghouse filed all the eVinci’s NRC pre-application materials as “proprietary”, the actual design details aren’t available to the public for review. “Disruption” I assume refers to hundreds of rule exemptions (licensing innovations) they filed as a non-LWR. Not judging, just stating the record. [2] 1. https://www.etec.energy.gov/Library/Main/Doc._No._1_SRE_Fuel_Element_Damage_Interim%20Report_11.15.1959_NAA-SR-4488.pdf https://www.etec.energy.gov/Library/Main/Doc._No._1_SRE_Fuel... 2. https://www.nrc.gov/reactors/new-reactors/advanced/licensing-activities/pre-application-activities/evinci.html https://www.nrc.gov/reactors/new-reactors/advanced/licensing...

rob74 4y ago

> Westinghouse looks to off-grid applications like remote communities and mine sites as the entry market for eVinci. Yeah, install a nuclear reactor at a remote mining site, probably without sufficiently trained personnel to take care of it. What could go wrong?

function_seven 4y ago
Why would you assume untrained personnel? These would still be regulated by the DoE.
- jimnotgym 4y ago
  What about security? In the UK nuclear installations are under 24/7 armed guard from a special police force. That would be expensive to maintain in a remote region, although I guess they already have security at diamond mines, or instance
  - tecleandor 4y ago
    I guess that comparing it to the cost of setting up a super long power line and maintaining it (sabotages, fires, whatever), maybe it's interesting.
  - inglor_cz 4y ago
    Vastness of rural US is a security factor on its own. Plenty of military installations in the desert aren't even fenced.
    - Swenrekcah 4y ago
      They’re perhaps not fenced but presumably they’re full of armed military personnel?
      - bell-cot 4y ago
        You've never really been out in the American West, have you? Just one example - the Nevada Test and Training Range alone is a bit over 4,500 square miles. https://en.m.wikipedia.org/wiki/Nevada_Test_and_Training_Range https://en.m.wikipedia.org/wiki/Nevada_Test_and_Training_Ran... Vs. Wikipedia says the entire U.S. Army (active duty) has ~485,000 personnel. Divide...and that's ~0.17 Army people per acre, even if the US Army had NO job except holding down the NTTR. (Which is actually US Air Force, BTW.) [Edit: But +1 - because in the bigger picture you make a valid point. However vast the open spaces, at the spots where the cool & expensive stuff sits, there does have to be some sort of "real" security. If only so dodgy locals don't swing by with a pair of bolt cutters, and start helping themselves.]

UltraViolence 4y ago

Until an explosion damages the heat-pipes and you get a runaway meltdown and explosion of the core after hydrogen gas builds up. Very realistic scenario if the thing is used in a war zone.

nebopolis 4y ago
Being sodium cooled, both a steam explosion and hydrogen gas generation via water is ac minimized. Lots of safety advantages to a coolant that is still liquid at operating core temperature with no added pressure. But of course liquid sodium does come with some other caveats that are of concern. Making it a sealed unit with minimum moving parts helps with some of those potential problems for sure. As does keeping the total thermal capacity relatively low, below the threshold where secondary fission products need active cooling to prevent meltdown even after the reactor is shutdown.