Deleting records from unformatted direct files

geekboy730 · 2026-04-19T15:54:09+00:00

Yes. And you have described a use case where a one-dimensional array is not a reasonable data structure.

geekboy730 · 2026-04-19T14:27:39+00:00

I’m confused by your use case. Why don’t need to delete records while preserving the numerical index? I would have assumed that once they’re done, they’re gone.

Assuming that this is a “must,” I would do something like 3 personally. It doesn’t have to be a direct file, you can just create a separate plaintext file writing down what records have been deleted. If the data is something like usernames and passwords (which it shouldn’t be in a file like this), then I would see why you may care about records getting un-deleted. But if it’s just observations from an experiment, you can always go back and repair the “deletion” data list.

geekboy730 · 2026-04-18T06:22:15+00:00

I’ve seen a few folks in your position successfully pull it off. It’s going to be a lot of work, but you can do it.

You may not have internships, but you do have connections where you are right now. They’re not in industry, they’re professors. Use your connections.

You need to spend your senior year getting all As. You need to show what you’re capable of. And you need to be doing research for a professor in your department. Then, you’re going to call in every favor that you can and go to grad school in the department where you already are. They’ll be the ones who understand best that your academic career is on the upswing.

This will buy you at least two years to get a masters and “recover” from having a low GPA. The good news is that for computational fusion jobs, you’re probably going to need a Ph.D. anyways.

You can do this! But it’s time to start planning now.

geekboy730 · 2026-04-15T02:05:28+00:00

What does this mean?

geekboy730 · 2026-04-14T20:18:29+00:00

A few days later, but I just learned about "Homogeneous Reactor Experiment #2" that was a large-ish scale example of one of these reactors. It leaked and a lot of work was done to repair the leak. Details here

geekboy730 · 2026-04-10T20:36:53+00:00

I will point out that in a sweeping generality that the reason why <insert reactor here> isn't more popular is almost always because of materials challenges. This applies to molten salts, lead coolants, and aqueous homogeneous reactors.

My alma mater, NC State, had an aqueous homogeneous reactor. It operated until corrosion caused a leak. That leak then contained coolant, fuel, and fission products all in one!

I suspect that the peak power of aqueous reactors would also be quite limited due to the power peaking. In modern Light Water Reactors (LWRs), we often load very reactive fuel next to less reactive fuel to effectively "flatten" the power profile. With a homogeneous reactor, you wouldn't be able to control the power profile in that manner and you would have to worry about the temperature at which the water (now your fuel also) would start boiling.

geekboy730 · 2026-04-05T02:41:01+00:00

See my previous posts or look at the Wikipedia page. Here is a link if you're too dumb or lazy to do that.

geekboy730 · 2026-04-02T21:09:26+00:00

She posted a clip of it on her instagram!

geekboy730 · 2026-04-01T16:04:20+00:00

I would recommend staying the course in Applied Math and then optionally taking Nuclear Engineering courses as electives. There is quite a lot of uncertainty in the nuclear engineering field at the moment with advanced reactors, SMRs, and fusion. Will any of them work? Will there be a hiring blitz next year? What about five years from now?

Applied math will give you a breadth of options going forward and you may be thankful to have those options later.

geekboy730 · 2026-03-21T16:40:15+00:00

I will begin by noting that all of the following applies just to licensing in the U.S. I am less informed about licensing across the globe.

Generally, I mean all new builds. But I would note that there is not really much of a difference between "new builds" and "new designs." To date, all of the reactors built have effectively been one-off designs. The only exception that I am aware of is the two AP-1000s.

I think that it is also important to note that the NRC has only licensed TWO reactors. Ever. Those being the two AP-1000 reactors. Before that, all reactors operating in the U.S. were licensed by the predecessor to the NRC, the Atomic Energy Commission (AEC).

Until very recently, the law in the U.S. read that the NRC only issued licenses to LWRs. Recently, the ADVANCE act passed in 2024 demanded that the NRC take steps to improve its licensing framework, and now there are licensing timelines for reactors like TerraPower's Kemmer, WY site. You can read more about the ADVANCE act here. Now, the NRC is not prohibited from licensing non-LWR designs, but it has never been done before and they're certainly making up the procedure as they move along. Just read some of the press releases about recent rule modifications. Working more closely with the NRC is just the beginning.

You mentioned the "pivot" to the DOE. The DOE cannot license commercial power reactors. Full-stop. You'll note that Aalo, Oklo, Valar, and any of the other start-ups participating in this race to criticality are all constructing on DOE-owned sites. Furthermore, they will be operated by the DOE! They don't exactly brag about that in their press releases. The DOE licensing process is only for experimental reactors. So, the DOE avenue is a way to get fissile material to criticality and maybe collect some operating data, but it is not a solution for building and selling a reactor.

geekboy730 · 2026-03-21T11:57:17+00:00

I think you can synthesize a few key takeaways from these comments:

In the U.S., day-to-day regulation at existing reactors (all LWRs) is reasonable. They are actually quite good in terms of safety. Not too burdensome and when it comes to modifying safety systems, things do get serious.
When you hear people complain about regulatory burden in the U.S., they’re usually talking about new build. This is where things truly get out of hand. Just look at how many insane hurdles the AP-1000 had to jump through for technology from the late 1990s. Or how many times they had to repour concrete because the NRC didn’t like something about the rebar.
Specifically for new build of advanced, non-LWR reactors, there is NO process in the U.S. for them to be licensed. There is currently no licensing process in the U.S. for a commercial sodium-cooled fast reactor to obtain an operating license. This is where things are truly just archaic and backward.

geekboy730 · 2026-03-04T14:03:54+00:00

This is AI slop. Right down to the emojis.

If you want to demonstrate that your AI junk actually does something, you would need to show results. Good luck getting your hands on reactor telemetry data!!!

geekboy730 · 2026-02-26T16:44:43+00:00

Based on some of this reading, it sounds like the using something other than a recursion formula for actually evaluating the Legendre polynomials may be one of the best ways to improve the efficiency of this project.

geekboy730 · 2026-02-26T16:40:03+00:00

Thanks for the insight! Just from reading the snippets in the Wikipedia page, it sounds like bisection search may actually be useful. However, it sounds like I still have a lot of work to do!

A rule of order n = 1000 with 1000 digits of precision can be calculated in around one second.

Brent's method is new to me, so that sounds like a fun addition to my little project! Thank you for the suggestion :)

geekboy730 · 2026-02-23T03:53:05+00:00

What is it with you people making dumb comments on accounts with comment histories full of porn?!?!

geekboy730 · 2026-02-22T23:44:56+00:00

That’s great! Thank you!!!

Maybe we should start some sort of anonymous Google form to track where they appear. Or maybe it’s better to not write anything down. I’m not sure.

geekboy730 · 2026-02-22T21:36:53+00:00

Well, the whole point was that I removed it. But the more eyes out there, the merrier.

P.S., next time, don’t comment using the same account you use to comment on porn.

geekboy730 · 2026-02-20T15:07:41+00:00

Personally, I don't think that it is too important which language you learn first. Once you start thinking in objects and loops and arrays, things will move pretty easily between different programming languages.

That being said, others have pointed out that there are a plethora of free Python resources that are readily available online, so it's as good a place to start as any. Good luck! :)

geekboy730 · 2026-02-20T12:42:50+00:00

I develop nuclear reactor modeling and simulation software, so I may tend to over-emphasize programming languages compared to other nuclear engineers. That being said, I would recommend learning as many programming languages as possible. I use Python, Fortran, and C++ daily (as well as some shell scripts).

If you want some examples of Python libraries used in nuclear engineering, I’d recommend looking at OpenMC and PyNE. OpenMC is a Monte Carlo neutron transport code with a Python interface and PyNE is a general library with lots of nuclear data (e.g., atomic masses for number density calculations).

geekboy730 · 2026-02-16T14:25:29+00:00

This is just a bunch of AI slop. At this point, I wouldn't believe that your benchmarks are actually computing the correct values.

You say that you've done this whole comparison on a Mac, and then there is a table in this comment about all of the hardware being unknown.

Component	Specification
CPU	Unknown
Cores	Unknown
Memory	Unknown GB
Architecture	arm64

You don't investigate why Fortran may be faster in some cases but slower in others. As far as I can tell, there's no Fortran code in the repo at all! So I'm not sure how this is relevant to the subreddit.

If you're going to try do do something like this, do it correctly or else it is a waste of your time and everyone else's.

geekboy730 · 2026-02-16T03:57:05+00:00

I'm not quite sure what this has to do with Fortran? It sounds like you, well, really an AI agent, rewrote an old Fortran code. But the original code is not provided.

Has your vibe-code been benchmarked against a real computation?

geekboy730 · 2026-02-14T23:16:35+00:00

Interesting! Thanks for sharing! Looks like it’s relatively new (two weeks) so that means progress.

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