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An unnamed contributor wrote:
NuScale will get the final approval nearly six years after starting the process:
On Friday, the Nuclear Regulatory Commission (NRC) announced that it would be issuing a certification to a new nuclear reactor design, making it just the seventh that has been approved for use in the US. But in some ways, it's a first: the design, from a company called NuScale, is a small modular reactor that can be constructed at a central facility and then moved to the site where it will be operated.
[...] Once complete, the certification is published in the Federal Register, allowing the design to be used in the US. Friday's announcement says that the NRC is all set to take the publication step.
The NRC will still have to weigh in on the sites where any of these reactors are deployed. Currently, one such site is in the works: a project called the Carbon Free Power Project, which will be situated at Idaho National Lab. That's expected to be operational in 2030 but has been facing some financial uncertainty. Utilities that might use the power produced there have grown hesitant to commit money to the project.
Previous stories:
First Major Modular Nuclear Project Having Difficulty Retaining Backers
US Gives First-Ever OK for Small Commercial Nuclear Reactor
The US Government Just Invested Big in Small-Scale Nuclear Power
Safer Nuclear Reactors on the Horizon
(Score: 4, Interesting) by turgid on Wednesday August 03 2022, @10:29AM (6 children)
I just read the summary at the link and it says that heat is extracted from the core by boiling water. Historically, there has been a problem with this design of reactor, and that is that the primary coolant is used directly in the turbines to turn the alternators.
You can see where this is going. There will be radioactive contamination in the primary coolant, so you end up having a radioactive turbine hall. No cooling loop is 100% sealed so there will be leaks of radioactive steam as well as radiation coming off of the steam and water that hasn't leaked.
This is one of the reasons that BWRs were replaced by PWRs. In a PWR, the primary coolant is under a lot of pressure so can get up to about 330C (maybe a bit more) and is then used to heat a secondary coolant via heat exchangers, which does not become contaminated and therefore not radioactive. The turbine hall is clean and safe for personnel. The added advantage is higher output because of the higher temperatures of the steam.
If they've solved these problems, it might work.
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].
(Score: 5, Interesting) by bradley13 on Wednesday August 03 2022, @10:58AM (3 children)
For what it's worth, the journalist has done what journalists always do: write about something they don't understand. Although the Nuscale website doesn't use the term, it's pretty clear that thus is a PWR. They write:
It still seems a fairly old fashioned design, but maybe that helps keep costs down.
Now they need to build hundreds of the things, not just one or two.
Everyone is somebody else's weirdo.
(Score: 2) by turgid on Wednesday August 03 2022, @01:09PM (1 child)
PWRs are very safe if you can keep water in them and keep it circulating in case of an accident. Modern designs that allow convective cooling are great because they can still remove the decay heat after shutdown if all the pumps fail. Obviously, the secondary cooling loop has to remain intact and there has to be somewhere for the heat to go.
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].
(Score: 3, Informative) by Immerman on Thursday August 04 2022, @04:38PM
They're claiming to be the first LWR to provide an unlimited coping time without power or additional water. I believe that means they can bring the core's power output down below what at least the secondary cooling loop can passively shed into the ambient air. https://www.nuscalepower.com/technology/design-innovations [nuscalepower.com]
(Score: 2) by Immerman on Thursday August 04 2022, @04:23PM
I recall hearing (speculation?) that the motivation for the old-fashioned design was to accelerate both design and regulatory approval.
It might not be as theoretically safe as something like the molten salt reactors others are working on - but it's well understood technology just packaged in a new way, so the regulators are less hesitant to approve it, confident that real-world safety issues are also well-understood and adequately addressed.
(Score: 3, Informative) by PinkyGigglebrain on Wednesday August 03 2022, @06:00PM (1 child)
just an infoblerb:
the water in PWR is usually at around 70 atmospheres, ~1000psi, to keep it from boiling at the temperatures the reactor pile has to operate at to be useful. Any leak in the system and the water can and will flash to steam instantly, completely remove the coolant from a working core in a short period of time.
The big advantage of MSR and Sodium cooled reactors is that the pressure of the coolant in the reactor's core itself is only a few PSI at most and it doesn't boil away in the event of a leak.
"Beware those who would deny you Knowledge, For in their hearts they dream themselves your Master."
(Score: 2) by turgid on Wednesday August 03 2022, @07:09PM
I believe that Fast Breeder Reactors (the ones that run on nuclear waste, ie plutonium) also run at atmospheric pressure (primary coolant is liquid metal, sodium/potassium eutectic) so can't explode. The problem there is that the primary coolant is liquid sodium/potassium (at high temperature) and the secondary is water so any leak from one into the other is an explosion risk. Also, the sodium becomes highly radioactive in the neutron flux. I believe there was an accident in Japan once where some primary coolant got out? Perhaps a solution might be an intermediate coolant loop using an inert gas such as carbon dioxide or helium?
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].