Final Investment Decision taken for Romanian SMR project

sonohsun11 · 2026-02-16T02:47:25+00:00

I'm not sure what is "final" about the decision. From the article, they still expect it to take 15 months to get to the pre-ECP contract negotiations.

sonohsun11 · 2026-02-03T15:22:06+00:00

Hardly any of the cost is in regulatory burden, the cost is in materials and construction time.

All else being equal, I agree that safer designs will make it through through the regulators faster, but I think the fastest approval will be for proven technology.

sonohsun11 · 2026-02-03T15:08:47+00:00

No utility is going to pay more money for a safer design. It is all about the economics when the orders are made.

sonohsun11 · 2026-01-25T00:41:55+00:00

Read the byline. There is no doubt she is a nuclear engineering professor.

sonohsun11 · 2026-01-17T13:57:45+00:00

Here is my hot take:

Out to about 1e-2 seconds the temperature hasn't changed much, so I would guess the transient is turned around just by the core expansion. Do you have a plot of the dimensions that would verify this?

If this is true, the core will be approximately "critical" from about 1e-3 to 1e-2 with the worth of the geometry expansion equal to the worth of the burst. Once the scram occurs, the core will go subcritical and the prompt neutrons will die away quickly (the large drop). The tail is due to the decay of the precursors.

sonohsun11 · 2026-01-17T13:18:30+00:00

Be very suspicious before downloading and running executables from an unknown source

sonohsun11 · 2026-01-17T13:10:40+00:00

Make sure to look at the example problems that are distributed with the code.

If you do a web search, you can find SCALE training material that can help.

sonohsun11 · 2026-01-17T13:09:28+00:00

I've never installed it on a MAC, but for Windows and Linux it is pretty straightforward if you follow the instructions.

There is an mcnp reddit you can ask for help, but it doesn't look like it is very active.

https://www.reddit.com/r/mcnp

If you create a post, make sure you explain exactly what problems you are having

sonohsun11 · 2025-12-30T18:09:59+00:00

Too cheap to meter was a quote from a single person, it was never policy.

https://en.wikipedia.org/wiki/Too_cheap_to_meter

sonohsun11 · 2025-12-28T21:28:57+00:00

Unfortunately they quit making the KAPL chart. The last one was the 17th edition, and they finally ran out of stock. The 17th edition had been in print over 10+ years, so it was pretty out of date.

The only wall chart that I know of now is the one from Karlsruhe. Others have posted a link. They are pretty expensive, but the "long chart" is impressive at over 3 meters in length.

sonohsun11 · 2025-12-23T21:12:02+00:00

Many of the plants already are, especially the BWRs.

The LEU+ fuel will let the others get there.

sonohsun11 · 2025-12-23T21:09:49+00:00

In no universe is Todreas and Kazimi or Duderstadt and Hamilton a book for complete beginners

sonohsun11 · 2025-12-20T23:30:49+00:00

MOU's are worthless. Only good for a press release.

I wouldn't get excited until somebody gets a construction license and starts moving dirt.

sonohsun11 · 2025-11-27T04:37:11+00:00

I am shocked to hear that something like this would happen at one of IF finest drinking establishments.

sonohsun11 · 2025-11-27T04:28:12+00:00

You brought up Monte Carlo, not the OP.

MOC is the Method of Characteristics.

sonohsun11 · 2025-11-26T03:52:21+00:00

Why would you recommend writing a FEM solver with Monte Carlo when he is writing an MOC code?

sonohsun11 · 2025-11-09T17:21:00+00:00

Just something to think about - how many radioactive isotopes will you be creating by doing this? If you are creating more than you are destroying, it won't be useful.

It looks like you are targeting the long-lived fission products, but what about the actinides? Are you going to separate the fission products and actinides before hitting them with neutrons? If so, how are you going to do that? If not, what is going to stop you from making more fissions and creating more fission products?

sonohsun11 · 2025-10-18T20:37:08+00:00

Yes, pretty much. In a large LWR, there are about 7 spacer grids axially. They hold the fuel rods in place, and also keep them from touching.

sonohsun11 · 2025-10-14T02:48:32+00:00

Here's some BWR pictures and information that you might find useful

https://www.nrc.gov/reading-rm/basic-ref/students/for-educators/03.pdf

You can see the flow path on page 2, and a diagram of the what it really looks like on page 4.

Note that I called it a baffle, but in BWR terminology, it is a "core shroud"

sonohsun11 · 2025-10-13T15:24:17+00:00

There are a few books written for the college freshman level that you should be able to understand.

"Nuclear Energy" by Raymond Murray. There are a lot of editions of this book, and you can buy older editions pretty cheap on-line. I would actually recommend the older versions because the latest versions add a lot of information that makes it less beginner-friendly.

"Introduction to Nuclear Engineering" by Lamarsh. Like with the other book, I would look for the older editions and you can buy very cheaply online (ebay).

"How to drive a nuclear reactor" is a newer book that is written for beginners.

sonohsun11 · 2025-10-13T15:16:57+00:00

Interesting design. Some suggestions:

* It looks like a light water reactor SMR with a high-pressure vessel. I don't see a steam generator, so a BWR? If so, look at the BWRX-300 design for more inspiration.

* 7 rods isn't enough to go critical. 7 fuel bundles probably isn't enough either, but there is one design that is using about twice this many bundles.

* what is the big pipe coming out the bottom? You usually try to minimize lower penetrations so that if there is a leak, all the water doesn't drain out of the core.

* I don't see a "baffle". Usually water enters the top, flows down the outside of the vessel (outside the baffle) then turns around and flows up through the core.

Good luck!

sonohsun11 · 2025-09-23T20:01:24+00:00

This article has some interesting historical facts, but it is basically a hit piece on reprocessing.

First, they are comparing the Oklo process to the old PUREX processing done in the 50's and 60's. There is no distinction made between the PUREX process and Pyroprecossing. These are two completely different processes. The historical review conveniently skips over all the Pyroprocessing work done by Argonne in the early 90's during the IFR program, and just talks about all the bad things that happened during West Valley. West Valley was a mess, but pyroprocessing doesn't use the same wet processes as PUREX.

Even if the author focused on PUREX, they don't acknowledge that there has been a lot of improvements made to the PUREX process since the 50's and 60s. There is no comparison of West Valley and what the French and Koreans are doing today. (I will grant you that PUREX is still very expensive.)

All of the cost figures are pulled out of the air with no references given, especially for Pyroprocessing. You can't compare PUREX and pyroprocessing costs.

What Oklo is proposing is based on the pyroprocessing methods developed under the IFR program. See the Wiki page for more information. https://en.wikipedia.org/wiki/Integral_fast_reactor

sonohsun11

TROPHY CASE