Nodraak · HackerTrans

Nodraak

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Guidance software of a Moon lander: preliminary study

blog.nodraak.fr

2 pointsby Nodraak6 lat temu0 comments

Hello World with Rust and WebAssembly: Throwing Ferris

blog.nodraak.fr

1 pointsby Nodraak6 lat temu0 comments

“Too much precision” bug

blog.nodraak.fr

1 pointsby Nodraak6 lat temu0 comments

comments

2 lata temudiscuss

> "As of early September 2022, 32 of France's 56 nuclear reactors were shut down"

This is cherry picking. Look at the 10 years, or even lifetime, average availability. It's 90 or 95%. The reason for this bad number is because of delayed maintenance due to COVID.

> "serious consequences for power plant cooling systems, as the drought reduced the amount of river water available for cooling."

The reduction of power output of French nuclear was something like 0.30%. You read that right. So I would call "serious consequences" a blatant lie.

3 lata temudiscuss

> one of the plant regularly leaks radioactive material

Please share numbers demonstration health hazards. For ex, bananas are radioactive. Should we outlaw bananas?

> rivers are getting too hot to cool down nuclear plants correctly

That's wrong. In 2022, the power output had to be reduced by 0.18% (not a typo) (https://twitter.com/energybants/status/1645696906327388160). In addition, Nuclear plants can work even in the desert: https://en.wikipedia.org/wiki/Palo_Verde_Nuclear_Generating_...

> nuclear plants are very unreliable

That's also wrong. Please share numbers. Nuclear has a load factor of 95% and its down time can be scheduled (maintenance). Wind has a load factor of 30-40% (and output is unpredictable), solar has a load factor of 20%, hydro requires mountains.

> the government wants to simplify control organism and laws around building new plants

When controls are too tight, nuclear is too slow ; when controls are too loose, nuclear is dangerous. Face je gagne, pile tu perds.

The goal is less CO2, and for that any low carbon energy source is good.

3 lata temudiscuss

Nice auto pilot! Very basic, but works well enough.

In the real world, you would derive physics equations (acceleration -> velocity -> position), add constraints and then solve everything to obtain an optimal trajectory (mostly in term of fuel, but you can add other constraints too, for ex due to radar-ground or Antenna-Earth visibility). I wrote a blog post about Apollo's algorithm: https://blog.nodraak.fr/2020/12/aerospace-sim-2-guidance-law... (Described in the second section ; the first section is about a naive algorithm similar to yours that in the end did not work as well as I wanted).

Also, thanks for the code, I wanted to do the same, but lost motivation when I could not really expose in a satisfying way the internal state out of these JS modules (it's not complicated in the end, but I'm simply not a frontend dev ; and I wanted to avoid forking and monkey patching everything and simply adding some JS code throught the console or something).

4 lata temudiscuss

Please look at yearly averages to avoid cherry picking.

Maintenance is planned every autumn to make sure that all the nuclear plants work when they are needed, ie. during winter.

4 lata temudiscuss

It is not exactly increasing enrichment capacity, it seems it's more complicated than than. From https://twitter.com/TristanKamin/status/1579828412474351616, "UTS" is basically a tradeoff between enriching at the same level more uranium VS enriching to a higher level the same amount of uranium.

About your "fun fact": I don't claim that everything is perfect, but except from going back to the stone age, nuclear is by any measure the least worst option.

4 lata temudiscuss

> because of massive defects or barely producing due to a lack of cooling water

This is false, and not the reason for the (currently) low load factor of nuclear.

Most reactors are off for maintenance, like they are each year in autumn, in order to be ready for the peak demand that winter is. This year might be slightly worse, but it's not unusual at all.

There is also no lack of cooling water. There is only a law that was set many years ago that can be changed without any impact on the safety of the reactors, and this law is limiting only for a few reactors a few days each year. Very anecdotal.

4 lata temudiscuss

> nuclear is demonstrably not working well

You are jumping to this conclusion way to fast.

First, you are cherry picking: you should look at the yearly load factor, not a random day and time of the year when it supports your argument. And you will find that nuclear has the highest load factor of all, 80-90%, while solar/PV will never be above 30-40% (because of physics, you can not change that).

Second, and since I just demonstrated that on a yearly timeframe nuclear works very well, the right question to ask is: why are there so many nuclear plants offline right now? The answer is quite simple, and is due to one of the advantage of nuclear: you can choose when to switch it on or off, for ex to perform maintenance. So, when is the best time to perform maintenance? Answer: just before the peak load, which happens in winter (Mondays around 8 AM in January, to be more precise), so you switch nuclear off in autumn, ie now. It's actually a good news that the load factor of nuclear is so low right now, it means that nuclear will be ready and will work well in a couple of months when we will need it the most.

> Currently Germany is exporting lots and lots of energy

Again, cherry picking, show me the yearly stat. But actually the only comment I will make here is about the criteria you are using: is exporting a lot of energy a good thing? I would say it depends. High variability is bad, it makes the grid unstable. I would rather have low and steady import/export rather than big swings. Exercise for the reader: what allows you to have steady production of electricity (nuclear, hydro, solar, wind, ...)?

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We need more nuclear. Simply because that's the only low carbon, controllable option that currently exists (hydro needs mountains, fossils are high carbon, solar/wind are intermittent)

5 lat temudiscuss

Small precision, because the title of the article is wrong:

JWST is a joint NASA–ESA–CSA project and is actually launched by ESA.

5 lat temudiscuss

Hey! Jumping in, because I'm learning German: do you have other suggestions appart from MaiLab?

5 lat temudiscuss

TL;DR: eating 1 kg of phosphogypsum each day yields 36 mSv/year. Conclusion: very very far from life-threatening ; nobody is going to die or get cancer because of this.

Oh God. This is Fukushima radioactive waters all again. I'm pissed: global warming is serious, and nuclear is our best bet. We dont need this fear-mongering non sense.

Anyway, let's get to the facts and see how radioactive and dangerous this thing actually is. Methodologie from https://en.wikipedia.org/wiki/Banana_equivalent_dose, section "Source of radioactivity".

Here is the data:

    1. Central Florida phosphogypsum averages 26 pCi/g radium
    2. Radium: 10**-7 Sv/Bq

This gives: 26 pCi/g radium * 3.7 * 10**10 Bq/Ci * 10**-7 Sv/Bq (radium) = 0.100 mSv per Kg of phosphogypsum So, if someone eats 1 kg of phosphogypsum per day, that would be 0.100 * 365 = 36 mSv/year.

Background dose is 5-10 mSv/year, a plane pilot or X-Ray machine operator gets around 25-50 mSv/year, an astronaut something like 500 mSv/year.

So, eating 365 kg per year will yield a higher than background dose, but nothing dangerous. I mean, it's probably dangerous to eat so much of this chemical stuff, but not because of radioactivity.

Sources:

    1. https://web.archive.org/web/20150219224641/http://www1.fipr.state.fl.us/PhosphatePrimer/0/684AE64864D115FE85256F88007AC781
    2. https://web.archive.org/web/20121026093251/https://www.epa.gov/rpdweb00/docs/federal/520-1-88-020.pdf - Page 156 and following ; p175 for Radium
    3. https://en.wikipedia.org/wiki/Phosphogypsum

5 lat temudiscuss

This sounds very illegal. From what I know, in France the notice period is 1 month if it is "meublé", or 3 months if the appartment is empty.

Edit: actually, I just checked and that's for tenants. If the landlord wants to break the contract to sell the property, it's 3 months for "meublé", 6 months otherwise.

6 lat temudiscuss

For anyone in Germany (or any country which is blocked by this website), here is the raw html. Save it and open it with your favorite web browser :) http://paste.awesom.eu/Y36k

6 lat temudiscuss

> Afaik originally the life-span for most reactors of that kind was 40 years

That's a lie, or at least an unprecise statement, mostly shared by the anti-nuclear who are looking for a reason to close reactors.

In France, reactors were designed to work for 40 without any major checkup ; and after 40 years, without any decommission deadline planned in advance, as long the "visite décennale" (in-depth inspection every 10 years) does not discover any major issue. So a reactor can totally work for 60, 70, 80, or even more.

6 lat temudiscuss

The original data seems to be available at [^1] but I dont see any spike around the 22-23 of June ... Let's wait to know more before saying anything stupid (looking at you Greenpeace)

[^1] https://www.stuk.fi/aiheet/sateily-ymparistossa/sateilytilan...

6 lat temudiscuss

I am a (aerospace) software engineer. I you wonder what trajectory the Apollo missions followed to go to the Moon, you can read my article about it: https://blog.nodraak.fr/2019/06/free-return-trajectory-1-fly...

6 lat temudiscuss

While I dont think it is specific to a region, it is probably specific to an age: verlan is quite used among late teens / young adults, while Javanais is more used by childs / young teens. I used to speak Javanais with my sisters as a way to speak without our parents understanding (hopefully!).

It is not really a "slang", but I thought it was similar and worth sharing

6 lat temudiscuss

Other French slang: Javanais https://en.wikipedia.org/wiki/Javanais

7 lat temudiscuss

To save other people a clic: "Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light." https://en.wikipedia.org/wiki/Birefringence

7 lat temudiscuss

Indeed, sorry. I focused on "higher up" while the important part was "gravity well"

7 lat temudiscuss

It's not only about altitude (going to space is easy), it's also about horizontal velocity (staying in space is hard: 8 km/sec is a lot).

I dont recall the exact number, but I think that altitude is 50% of the energy, the other 50% is horizontal velocity. So building a rocket on top of the Everest would save us maybe 5% (10 km vs 100 km altitude), that's not much