Re: OT - overcast with almost no wind. Wind and solar not doing much.

It actually said that the RBMK could not be licensed in the UK, which is slightly different.

Because it was inherently unsafe.

No, You could not license a reactor on Dartmoor because the background radiation there is above allowable limits for nuclear power station workers. Nevertheless is would not be inherently unsafe to do so.

No. Just about all technology poses potential risks. The issue is whether you can manage it to the current prevailing standards.

In Ukraine, the population density is much lower, and they need more energy both for industrial reasons and because of the harsher winters. They are therefore prepared to accept greater risks than we do. We have a couple of reactors on the edge of significant towns, because they are intrinsically safer than RBMK. Not because they are "safe" as opposed to "unsafe".

newshound snipped-for-privacy@gmail.com wrote

But some like the Canadian CANDU design fails safe.

The RBMKs rely on the operators doing the right thing and not playing silly buggers and so is inherently unsafe.

Its more complicated than that.

They didn’t have to accept greater risks.

But they aren't inherently unsafe.

This made controlling the RBMK a very laborious, mentally and physically demanding task requiring the timely adjustment of dozens of parameters every minute, around the clock, constantly wearing out switches such as those used for the control rods and causing operators to sweat.

The enrichment percentage was thus increased to 2.0% to alleviate <=== these issues.

The RBMK was considered by some in the Soviet Union to be already obsolete shortly after the commissioning of Chernobyl unit 1. Aleksandrov and Dollezhal did not investigate further or even deeply understand the problems in the RBMK, and the void coefficient was not analyzed in the manuals for the reactor.

Engineers at Chernobyl unit 1 had to create solutions to many of the RBMK's flaws such as a lack of protection against no feedwater supply. Leningrad and Chernobyl units 1 both had partial meltdowns that were treated (alongside other nuclear accidents at power plants) as state secrets and so were unknown even to other workers at those same plants.

By 1980, NIKIET realized after completing a confidential study that accidents with the RBMK were likely even during normal operation, but no action was taken to correct the RBMK's flaws. "

That's why they can still be in service. Fuel change.

Paul

Paul snipped-for-privacy@needed.invalid wrote

Sorry, by typo, that should have been

But they are inherently unsafe.

That should be clear from my earlier comment about operator error.

Just not a useful term. Aeroplanes are inherently unsafe, e.g. MH370.

newshound snipped-for-privacy@gmail.com wrote

It is with nuke reactors. The Canadian CANDUs are much safer than the Russian RBMKs.

But still vastly safer than driving to the airport.

They are different, I will say no more, but there is a good reason why we discontinued the (somewhat comparable) SGHWR.

newshound snipped-for-privacy@gmail.com wrote

They are radically different. The CANDUs fail safe. The RBMKs don’t and need the operators to know what they are doing and not play silly buggers.

Separate matter entirely. The UK never considered using RBMKs either, for a reason.

For the reason I explained. They would not get a license, because they don't meet our principles. There is not a black line between "safe" and "unsafe", it's a continuum. There's a price to safety; not surprisingly, different societies come to different conclusions in the cost-benefit analysis.

The RBMK was a design that was inherently unstable - it had zones of positive feedback to the controls. a bit like flying a plane where the controls work backwards at some speeds. If you know what those speeds are, you can operate the plane safely enough. The Russian operators seemed to not have been trained enough to understanbd that. But the real hazard was the total lack of secondary containment. Every single western reactor since windscale has been built on the principle that a core meltdown shall not result in undue release of radiation.

To this end the reactor vessels are enclosed in concrete containers, that are only breached by lockable service dots and the necessary pipes and wires needed to run te reactor. So when a reactor melts down - as happened in 3MI and in Fuku, the molten core may eat through the pressure vessel, but the only radiation escape will be via the pipes used to carry coolant in an out.

The molten core ends up at the bottom of the concrete containment, and is simply left to cool down - for decades.

In Chernobyly, the core was uncontainned, it melted its way through to underneath the reactor, but the fire raging in the graphite carried tonnes of radioactive particles and spread them all over Europe.

In short nearly all the radioactivity that could escape from a reactor did escape. It is not possible to conceive of a worse reactor accident. No reactor today could release so much.

And yet Chernobyl had very little effect on the environment.

Yes, the reactor site itself is still viciously radioactive, but is now contained. Total death toll was less than a hundred, total cancers was not in the hundreds of thousands years later as predicted by LNT, but was under

Chernoblyl ironically, to all but ArtStudents?, is an object lesson in how safe nuclear power is, in comparison to say COVID 19, as well as how crap the design and training of the reactor and its operators was, in the good old USSR days.

Chernobyl was the worst possible nuclear accident. Meltdown, and zero containment.

And yet it really hardly ranks on the scale of industrial accidents. Or natural disasters.

Oh, such as the 1975 Banqiao Dam failure, you mean, that caused 170,000 or so deaths?

IIRC it could be unstable at low output power levels, from what I recall of the Winky article about it. Again IIRC, the operators hadn't been trained in those aspects.

Yes, that's certainly a basic safety case principle. But nothing you could actually call "secondary containment" in Magnox or AGR plant

In an AGR, the concrete is the pressure vessel. In conventional nuclear speak, secondary containment means secondary to the pressure vessel. Logically, the pressure vessel is the secondary containment, after the fuel cladding. But the pressure vessel is usually regarded as the primary containment.

Yes there was a concrete biological shield in Magnox steel pressure vessel stations, but this not sealed to the atmosphere, in fact it is cooled from the inside by air, which is exhausted from through unfiltered chimneys on the roof.

The doors are locked, to stop people wandering in. But they are just industrial doors.

So when a reactor melts down - as

Well, underneath the reactor was a *lot* of structural concrete. They did worry about that being breached, and dug a tunnel underneath to check, and to add cooling.

Agreed (short of a Chicxulub type event)

Indeed

The United Nations Scientific Committee on the Effects of Atomic Radiation has concluded that, apart from some 5000 thyroid cancers (resulting in 15 fatalities), "there is no evidence of a major public health impact attributable to radiation exposure 20 years after the accident."

Agreed

Agreed. Much less serious than the Japanese tsunami.

>

>>> In Japan, this was 40-year old plant (and design concepts) on the
>>> point of being decommissioned that got caught out by an extreme event,
>>> well beyond the design basis. Rather like, say, a tornado striking the
>>> Shard or the Severn Bridge.
>>
>> More accurately by stupidly citing the aux power generation where
>> a tsunami which wouldn?t affect the reactors themselves would take
>> out the aux power generation. Nothing really to do with nukes at all. >>
> No, the problem was they assumed a maximum sized tsunami of (iirc) 8
> metres. Back in those days, nuclear plant safety cases were
> deterministic and assumed what we called in the UK a "Maximum Credible > Accident".

Sounds similar to the bullshit in the UK - a double socket which can only handle 20A continuous, yet you can plug two 13A devices into it. But of course the chances of that are.... oops your house burnt down.

And saved thousands of lives

The fact is that of and by itself nuclear power is way safer - even with chernobyl, - than the politicians and journalists who demonize it and cause massive damage as a result.