I spend most of my time on substack complaining about our absurdly exaggerated fear of low dose rate (2 mSv/d or less) radiation, fostered by the nuclear establishment, for motives ranging from perverse regulator incentives to institutional greed. Lauriston Taylor, a preeminent pioneer in radiation safety, said it best:
Hello Jack: In your argument you implicitly assume the reactor is a water cooled unit as are most existing power reactors. Under accident conditions these reactors vent certain radioactive fission product gases. Please do not stand in the way of other reactor types that do not share these constraints.
Whatever the reactor technology, I can come up with multiple scenarios which result in a release, but if I'm being really lazy I'll just postulate a bunker buster. What's standing in the way of nuclear power is unbridled, perversely incentivized regulation. If it were replaced by an underwriter based regulation, I can assure you the insurer will want a buffer zone. At a minimum, your premium will depend on the extent of your buffer zone.
Jack, great points, as always. You mention a 1 MW microreactor would require a 365 meter buffer zone. If one places such microreactors 365 meters underground, then one could place them virtually anywhere (limited only by suitable underground conditions) — including below cityblocks. Or are there other considerations, as well?
Frankly, I find micro-reactors pretty uninteresting. You cannot solve a problem as big as energy poverty and global warming with tiny reactors, There are important economies of scale in nuclear. We need Big Modular Reactors, as big as we can build in an assembly line fashion.
In a sense, each fuel assembly in an lwr is like a micro reactor. Unfortunately, bundling the fuel assemblies so close together in a single pressure vessel and running them at high power density allows for various failure mechanisms. In many ways, the micro reactor push is just about subdividing those fuel assemblies into smaller vessels to increase the specific heat dissipating surface area. Add in some natural circulation systems, lower the power density, use less reactive coolants, better fuels, and overall, it’s less prone to melt on you. Seems pretty sensible and justifies that we consider a different treatment for the exclusion zone.
A similar example of size and power choice occurs in lithium battery cells. For your tesla model s, you could have 1 big boy cell which could never handle the heat loads, or you can have thousands of smaller cells linked together which can fully handle the heat loads, pretty much passively, without breaking the cells.
The count of micro reactors to power a city is neither here nor there. It’s like trying to scare people by quoting the number of LiPo cells in a battery pack, or the number of transistors in a chip, or the number of car engines on the road. Oh no, it’s a very big number! For one, the reactors will probably all be coupled to one large balance of plant so you still get your economies of scale. Yes each reactor may require its own control system and you suffer from less efficient RPVs and HXs and tubing, but it’s likely that the mere number of units has a small effect on the total cost that is outweighed by economies of factory production similar to aircraft (~2000 wide body /year globally) or automobiles (~100M/yr) globally.
The analogy between Li batteries and reactors is a big stretch, i cant pretend to be a battery expert but it appears from Tesla's 4680 cell that Li cell economies of scale are more or less exhausted at 100 Wh. After that it's just a matter of wiring them together and wiring is far cheaper than piping
It turns out that a standard fuel element has about the same power output, 4 MWt,
as a small micro-reactor. But you put a thousand of those is a single vessel to achieve
large economies of scale in neutron efficiency, plumbing and control.
But rather than engage in a fruitless technical argument in this venue, I will repeat "Let a thousand flowers bloom in a competitive market free of government interference."
and we will see who wins. My bet is on Big Modular Reactors which is in line with your wide body aircraft analogy.
I agree. Big Modular Reactors should be as big as can be moved over land. Even if we could manufacture millions of microreactors, there will still be regulatory burdens in various countries. If we need an on-site safety officer 24/7, no big deal for a 500MW plant.
The land transportation constraint is expensive and unnecessary. It is one of the AP1000's faults. Most of the population lives near a coast or a navigable river. And we need cooling water. We must have bigger modules than you can transport over land. And we must avoid the Nuscale blunder. They put a bunch of land transportable modules in a massive, site built structure. Really not that different from the AP1000.
500 miles is roughly 5% loss with 700 kV AC. We can go farther with higher voltage and/or DC. Only a tiny proportion of the US population is more than 500 miles from the coast or a navigable river (including the Great Lakes). How many times do I have to tell you guys, do the easy stuff first.
The important feature of Natrium is its a breeder. An economically successful breeder would be a wonderful step forward. But I doubt if even Gates and buddies can pull it off in the USA. If I were Gates, I'd head to some 3rd world country where I have done a lot of medical good, and cash in those chips.
The Natrium tank is a silly add on, but in an NRC-like regulatory regime, it could play a role in keeping the regulator out of the turbine hall.
Hello Jack: In your argument you implicitly assume the reactor is a water cooled unit as are most existing power reactors. Under accident conditions these reactors vent certain radioactive fission product gases. Please do not stand in the way of other reactor types that do not share these constraints.
Charles,
Whatever the reactor technology, I can come up with multiple scenarios which result in a release, but if I'm being really lazy I'll just postulate a bunker buster. What's standing in the way of nuclear power is unbridled, perversely incentivized regulation. If it were replaced by an underwriter based regulation, I can assure you the insurer will want a buffer zone. At a minimum, your premium will depend on the extent of your buffer zone.
Jack, great points, as always. You mention a 1 MW microreactor would require a 365 meter buffer zone. If one places such microreactors 365 meters underground, then one could place them virtually anywhere (limited only by suitable underground conditions) — including below cityblocks. Or are there other considerations, as well?
Johann,
Frankly, I find micro-reactors pretty uninteresting. You cannot solve a problem as big as energy poverty and global warming with tiny reactors, There are important economies of scale in nuclear. We need Big Modular Reactors, as big as we can build in an assembly line fashion.
see https://jackdevanney.substack.com/p/shipyard-production-of-nuclear-power
There is no point in serving a million person city with well over a 1000 1 MW microreactors, buried or not.
Microreactors may have a niche market in small isolated communities. In these communities, providing the necessary buffer zone will be no problem.
In a sense, each fuel assembly in an lwr is like a micro reactor. Unfortunately, bundling the fuel assemblies so close together in a single pressure vessel and running them at high power density allows for various failure mechanisms. In many ways, the micro reactor push is just about subdividing those fuel assemblies into smaller vessels to increase the specific heat dissipating surface area. Add in some natural circulation systems, lower the power density, use less reactive coolants, better fuels, and overall, it’s less prone to melt on you. Seems pretty sensible and justifies that we consider a different treatment for the exclusion zone.
A similar example of size and power choice occurs in lithium battery cells. For your tesla model s, you could have 1 big boy cell which could never handle the heat loads, or you can have thousands of smaller cells linked together which can fully handle the heat loads, pretty much passively, without breaking the cells.
The count of micro reactors to power a city is neither here nor there. It’s like trying to scare people by quoting the number of LiPo cells in a battery pack, or the number of transistors in a chip, or the number of car engines on the road. Oh no, it’s a very big number! For one, the reactors will probably all be coupled to one large balance of plant so you still get your economies of scale. Yes each reactor may require its own control system and you suffer from less efficient RPVs and HXs and tubing, but it’s likely that the mere number of units has a small effect on the total cost that is outweighed by economies of factory production similar to aircraft (~2000 wide body /year globally) or automobiles (~100M/yr) globally.
Lorenzo,
The analogy between Li batteries and reactors is a big stretch, i cant pretend to be a battery expert but it appears from Tesla's 4680 cell that Li cell economies of scale are more or less exhausted at 100 Wh. After that it's just a matter of wiring them together and wiring is far cheaper than piping
It turns out that a standard fuel element has about the same power output, 4 MWt,
as a small micro-reactor. But you put a thousand of those is a single vessel to achieve
large economies of scale in neutron efficiency, plumbing and control.
But rather than engage in a fruitless technical argument in this venue, I will repeat "Let a thousand flowers bloom in a competitive market free of government interference."
and we will see who wins. My bet is on Big Modular Reactors which is in line with your wide body aircraft analogy.
I agree. Big Modular Reactors should be as big as can be moved over land. Even if we could manufacture millions of microreactors, there will still be regulatory burdens in various countries. If we need an on-site safety officer 24/7, no big deal for a 500MW plant.
David,
The land transportation constraint is expensive and unnecessary. It is one of the AP1000's faults. Most of the population lives near a coast or a navigable river. And we need cooling water. We must have bigger modules than you can transport over land. And we must avoid the Nuscale blunder. They put a bunch of land transportable modules in a massive, site built structure. Really not that different from the AP1000.
What do you see as the solution for areas like most of the USA, far from the ocean? Is Natrium on the right track?
500 miles is roughly 5% loss with 700 kV AC. We can go farther with higher voltage and/or DC. Only a tiny proportion of the US population is more than 500 miles from the coast or a navigable river (including the Great Lakes). How many times do I have to tell you guys, do the easy stuff first.
The important feature of Natrium is its a breeder. An economically successful breeder would be a wonderful step forward. But I doubt if even Gates and buddies can pull it off in the USA. If I were Gates, I'd head to some 3rd world country where I have done a lot of medical good, and cash in those chips.
The Natrium tank is a silly add on, but in an NRC-like regulatory regime, it could play a role in keeping the regulator out of the turbine hall.