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Comment by Comevius | Hacker News Reader

Thankfully the reactors are behind the camera streaming the administrative building. Hopefully nothing goes wrong during the takeover. The reactor containment itself is robust, but the potential for human error in a war that keeps escalating should not be discounted.

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Internet speculation is that the power plant will be shut down once taken over. Which at least minimizes the ongoing risk of human error. Heck, shutting down is probably a far simpler process than continuing to run - nuclear power plants are designed to be shut down if necessary.

Well, shutting down nuclear reactor is not a simple process — it has to be actively cooled for weeks after being disconnected, which requires power, which you don’t have because you shut it down. So there should be either on-site generators (burning fuel) or external power . That’s why power stations usually have multiple reactors which are serviced on schedule, so it always has some generation happening.

None of it can be relied on during the war.

Shutting down and not having power to cooldown is how Fukushima happened. Emergency shutdown drill is how Chornobyl’ happened

> Emergency shutdown drill is how Chornobyl’ happened

And not being informed of well-known (in higher Soviet echelons) serious reactor flaws, like the grafite on the rods being inserted into the reactor core initially spiking the fission process significantly.

Shutting down is a much safer condition than operating. The decay heat decreases massively over time (huge difference between minutes / hours / days /weeks) and gets safer the longer it has been off.

Also if it's online, the electricity needs to go somewhere: any disruption to the electrical grid and it'd have to go off - probably at a bad time. Better to go through the shutdown in a planned manner while the outside situation is (relatively) stable.

What would happen if the grid connection was severed by bombing? Is there no emergency shutdown mechanism where the output is just dumped into some artificial load?

Then again, a 5700MW resistor might require a bit of cooling.

First, reactor protection systems will start reducing power down to 40% nominal if the turbogenerator load disappears (search for URB in https://inis.iaea.org/collection/NCLCollectionStore/_Public/...).

The power would not be dumped into a resistor: the power would be dumped in form of heat with the turbogenerator disconnected from steam. I expect that you can "just" dump it in the condenser and use the standard cooling of the condenser to dump it into the local body of water. If that's insufficient, one can dump steam from the secondary loop into atmosphere (which necessitates adding water there). You can play with a vver-1000 simulator and see how many of these things work; the simulator whose manual I'm citing above can be easily found on the internet.

It's reactor heat -> (heat exchanger) -> steam -> (steam turbine) -> electricity.

If you disconnect the load, you need to stop putting steam through the turbine and dump it somewhere else (i.e. a condenser). All steam turbine plants (including coal) have something similar.

Stoo the turbines and dump the st team/heat into the lake instead?

I was about to mention that reactors often have fuel generators but I remember that the invading force is famous for selling the gas from their tanks to pocket the money…

Given the quality of Russian supply planning and execution it seems as if the biggest danger could be emergency generator fuel supplies getting forcefully repurposed. Good luck doing a safe shutdown...

I mean, they're also designed to run, and they do that most of the time.

Given the continuous need for cooling and containment, and within the context of a war, does it really matter if a fission power plant is running or shut down in terms of environmental security?

Russian forces have been destroying substations to kill electricity and this is the largest power station in Ukraine. It is not unreasonable at all to think that shutting it down and making it hard to get back up (to destabilize or shut down the Ukrainian power grid) is part of the Russian attack strategy.

It seems trivial to cut the big power lines if you want to cut power?

Ukraine is a big country. Meanwhile, this power plant represents 40 % of Ukraine's nuclear power generating capacity, which in turn is responsible for ~50 % of power generation. So this one plant is around 20 % of the total generating capacity in Ukraine.

Since Ukraine is no longer connected to the Ex-Soviet power grid, it is now an isolated grid and has to generate all electricity domestically. That's why the Ukraine is trying to create an interconnection with the EU grid as quickly as possible.

They're much less hazardous in a "cold shutdown" state. Decay heat is highest immediately after shutdown and decreases over time.

Anything can go wrong AFTER takeover. Russians can convert power plant into nuclear landmine and blow up it on retreat. This is war between two nuclear states, so nuclear weapon will be used eventually.

> This is war between two nuclear states, so nuclear weapon will be used eventually.

Ukraine is not a nuclear state as it does not have nuclear weapons.

We promised to not have it in return for not being invaded, so technically we are a nuclear state without any weapons present at this moment (as far as publicly known).

Since we have both technological expertise and practical means (from uranium ores to delivery systems), it’s a matter of time.

No nukes means not a nuclear state.

The former nukes belonged to the USSR and only they had the codes to arm them.

So tell us, which of the letters in USSR is for "Russia"?

RSFSR - Russia is officially recognized as continuation state of USSR by the UN

Can you point to an official document, such as voting by UN members, to put RF into security council of UN? I cannot find any. RF is not a founder of UN, so it puzzling for me, how they are able to sit permanently in Security Council. Is there an exception for RF in UN statute written somewhere?

I wondered the same thing recently. Found this legal academic analysis of the succession of member states.

The conclusion part made me think that the subject was negociated between constituant parts in the devolution treaty. However the paper does highlight that the UN is under ever more pressure for rule-based functioning and transparency, so who knows.

Personally if it were me, I'd rather try and get Russia's membership or voting rights suspended, based on the fact that article 4 states that the UN is for peace loving nations. In the current climate this has a chance of passing in the general assembly, where the veto can not be used. Russia has evoked article 41 'right of self-defense' but that seems problematic.

Another question is if you want to exclude Russia. It sets a precedent, and erodes the position of the UN if not (near-) unanimous. The previous vote had 144 out of 193 voting against Russia, with only 5 against (Russia, Belarus, Venezuela, etc)

https://scholarship.law.cornell.edu/cgi/viewcontent.cgi?arti...

> Can you point to official documents, such as voting by UN members to put RF into security council of UN?

No idea, I haven't seen any. Another thing Russia inherited from USSR war nukes as well as debt.

> from USSR war nukes

edit (I misspelled): from USSR was nukes

Turns out it's just inertia, also the last constituent member of USSR to leave (and thus logical successor) is... Kazakhstan

Not just inertia, but also military and nukes

None, but unlike Ukraine, russia had the codes and took them when they left the USSR

>so technically we are a nuclear state without any weapons present at this moment

You'd still be prevented by NPT (which Ukraine is part of) like all other non-nuclear states, even without the Budapest Memorandum.

-Unless the Russian forces have way better connections than we give them credit for, they can not control which way the wind blows. At the moment, the winds come from the southeast, so a lot of the fallout would end up in Russia.

As far as I can tell, this power station is in the south-east. A wind from the south-east would dump fallout in central Ukraine, not Russia.

-Most definitely, but there'd be plenty to spare for Russia, too.

Blown up nuclear power plants are equal opportunity weapons.

Judging from the way this war develops, it’s nit like they care about Russia that much

I wouldn’t count having nuclear power plants as being a nuclear state. There’s a world of difference between power plants and weapons. A war between two countries with nuclear weapons would be on a whole other level.

I’ve read/heard the point is to destroy the reactor for the Russians. They’ve attempted to reach out to the Russians to no avail. It produces 1/4 the country’s power.

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