tarre

Don Quixote: "To attain to eminence in letters costs a man time, watching, hunger, nakedness, headaches, indigestions, and other things of the sort."

Is is being CsTreated since eight years, why we do have radioactive Caesium still accumulating in the coast?

As far as I know, this is because about 10 PBq of Cs-137 was released during the accident and the released material is transferred by ocean currents. CsTreat is being used for purification of the water, which is pumped into and out the containment to keep core remnants cool. Nowadays the releases are very limited if any.

This is very reasonable, but storing sand for 50 years somewhere is technically feasible...

You're right. Also CsTreat is solid, rock/sand-like material. It can be stored as mixed into concrete and disposed as low/intermediate-level radioactive waste.

Now you probably want to ask: Why there is huge amounts of radioactive water stored at the plant site? Because of tritium, which is chemically equal to hydrogen and is very expensive to separate from water. Under normal operating licenses of NPPs, you could release such water into environment, but at Fukushima standards are nowadays peculiar.

There are reasons, why not to do that:

1) DF doesn't add up like that at low concentrations. Then it comes down to selectivity of the material. Sodium and cesium have similar chemical characteristics, but CsTreat is very efficient in selecting Cs over Na.

2) Material you are using as filter becomes radioactive waste. You want to keep the volume at minimum.

3) With CsTreat you already reach radioactive Cs levels below measurable limit. There is no reason to try to remove more Cs from that water :)

Decontamination factor of 100 is rather terrible compared to DF of over 8 million of actual filter materials, which are being used at Fukushima: https://www.fortum.com/sites/g/files/rkxjap146/files/documen...

See also: https://www.fortum.com/products-and-services/power-plant-ser...

Hopefully one day ESA will also use radioisotope thermoelectric generators... :( https://en.m.wikipedia.org/wiki/Rosetta_(spacecraft)

I didn't know about those reactors. Interesting.

When writing the answer, I didn't even consider, that those reactors need to be fast reactors. In retrospect it is obvious, but makes controlling the power even harder.

Thanks for correction. Unfortunately I'm not able to edit it anymore.

In fact the fission[1] part in such small scale is hard. Curiosity and other probes using thermonuclear batteries harness alpha decay[2], which is relatively easy as it happens whether or not you want it to happen, but creates also much less power. In that case the hard part is to obtain material with appropriate half-life and other properties. Perhaps best material for this is Pu-238, which is far more expensive to create than weapons grade plutonium.

1. https://en.m.wikipedia.org/wiki/Nuclear_fission

2. https://en.m.wikipedia.org/wiki/Alpha_decay

We were both in a very small school in the countryside and when I was on 5th and she on 6th grade, we had wonderful teacher, Harri Ketamo (Google him and you'll end up wondering, what on earth he was doing in that school). Harri was especially interested in teaching mathematics. As there was only about ten pupils in the class, he had possibility to teach more advanced pupils further covering among other things programming and prime numbers.

I don't remember if it was in school or after school, when we had with Kaisa a debate over whether or not there was infinite number of prime numbers. The next day or so she presented, that it has been proven and here it is. Back in those days I didn't get it completely, but she was already there.

I still remember Kaisa telling in primary school, that Euclid's proof of infinite number of prime numbers is often considered as the most beautiful proof in mathematics.

Curiosity has a battery of 5 kg and it delivers 2 kW thermal and 125 W electric power.

Maybe the biggest drawback for tritium is the decay energy of 0.02 MeV compared to 5 MeV of Pu238. On longer missions also half-life may create problems (12 years / 70 years).

E: I'm very slow with my phone...

In Finland the most common reason is, that hardly any suitable rivers exist any more as they have been dammed.

Is there large possibility to find any wrecks on this area?

Nuclear waste is waste because it doesn't contain enough fissile nuclides (i.e. nuclides, which could produce heat in fission). It has almost nothing to do with radioactivity or decay power. Radioactivity just makes it harder to manage.

But you have it right: The decay power density of nuclear waste is quite soon not enough for such a probe.

This article could be applied to the organizers of huge international sporting events like FIFA and Olympic committee. I would love to see the books of those organisations checked.

Moreover in many countries the taxes are related to CO2 emissions, which will result in savings as well.

I think even one satellite is enough, if you have enough data points. You can tune the clocks based on the signals captured, when the location of the plane was known. After that each signal gives you a sphere, on which the plane is supposed to be. With reasonable assumptions about the altitude and speed of the plane, you should be able to locate the plane with enough accuracy to determine, if it was in the middle of an ocean or close to land.

I think they would be better off offering Win7 at discounted price. My wife asked me to install Ubuntu on her new laptop after short experiment with Win8 and now she is also trying to convince her very untechnical parents to switch from Win XP to Ubuntu.

At times like this, I'm reminded of the nuclear power plants of the world and their automation based on punched cards.

When speaking about systems, which need maximal reliability and are strictly controlled by authorities (air planes, nuclear power plants, medical treatment devices, space related stuff), updating existing and once approved systems is so painful, that you often do all you can to avoid it. That's a sad state of affairs.

Thanks for sharing the link. It was a very good read.

I am not an expert on this area, but I have got impression, that the German WW2-era assault rifles had quite complex design and they were expensive to manufacture. I think AK47 was exactly the opposite.

This is a very interesting tournament. AFAIK it is the only computer tournament with long time controls and equal hardware for both sides. I have been following it for some years already since the times of Old TCEC. The most interesting games annotated by GM or FM level players can be found here [1]. My favourite is the game Old TCEC Elite Match - Season 1 game 1.1, in which Houdini crushed Rybka with black pieces very convincingly by sacrificing 3 pawns to get a devastating advantage.

[1] http://www.tcec-chess.net/annotated_games.php

Did you try to send them just the pdf-file? That worked for me.

Water has quite low thermal conductivity (~0.6 W/(m*K)). If you exclude convection you can easily have such a temperature difference. For example with heat flux of 100 W/m2 you have 60 K temperature difference over a 36 cm thick layer of water.

You should not forget, that the result depends heavily also on the listener. Probably the hardest to understand English I have ever heard has been spoken by two native Englishmen who I met last year at a hostel in Spain. Similarly in my opinion the most clear English is spoken in Germany and the Nordic countries. It's just a matter of what you are used to.

You don't need to fake it. You just need to know the location of the satellites and delay the signals appropriately.

Unused nuclear fuel has very low radioactivity. It is the fission products, which are the problem regarding radioactivity. Were it a used fuel bundle, they wouldn't be standing there.

Everyone I have talked with about DST has had opinion, that the time to be chosen as base time used around year is the summer time. I would also change daylight at summer from 5am to 8pm, but i would also rather have in winter daylight at 16pm than 8am

Atomic mass is totally different thing than density