[wolfekeeper]

The 737MAX has a failsafe which has so far killed 346 people who would have completed their journeys safely without it.

The shutdown sequence for the RBMK reactor has worked every time. Problem with Chernobyl is that the operators were experimenting with a "home-made" emergency procedure (using the residual momentum of the generators and pumps to close down the system without using the backups) that was strictly forbidden in the manual.     

Fukushima was correctly designed to withstand the "100 year" tsunami but not the 1000 year beast that killed it. To do so would have made the design uneconomic. Part of the problem is one of public perception: "reactors are dangerous so must be sited on the coast" or "humans cannot be trusted to fly airplanes".

There's always a long list of reasons why any particular thing fails. And with hindsight they're nearly always obvious. But that doesn't stop them happening. With a properly trained crew, the 737Max flights could have been saved; failure of the tail actuator- there's procedure for that which could have worked; it just wasn't in the 737 manual any more, it had been removed.

Among other issues with your analysis, all conventional nuclear reactors need a large water source for cooling. Reactors are often placed on the coast because that's a good source of water.

If you only design for a hundred year event, and there's several hundred reactors, then if your estimate is accurate (they're usually very conservative), that's more than one failure per year.

[alancalverd]

You design each station for the 100 or 1000 year event at that site. AFAIK that does not include tsunamis on the UK or French coasts.

[charles1948]

The 737MAX has a failsafe which has so far killed 346 people who would have completed their journeys safely without it.

The shutdown sequence for the RBMK reactor has worked every time. Problem with Chernobyl is that the operators were experimenting with a "home-made" emergency procedure (using the residual momentum of the generators and pumps to close down the system without using the backups) that was strictly forbidden in the manual.     

Fukushima was correctly designed to withstand the "100 year" tsunami but not the 1000 year beast that killed it. To do so would have made the design uneconomic. Part of the problem is one of public perception: "reactors are dangerous so must be sited on the coast" or "humans cannot be trusted to fly airplanes".

There's always a long list of reasons why any particular thing fails. And with hindsight they're nearly always obvious. But that doesn't stop them happening. With a properly trained crew, the 737Max flights could have been saved; failure of the tail actuator- there's procedure for that which could have worked; it just wasn't in the 737 manual any more, it had been removed.

Among other issues with your analysis, all conventional nuclear reactors need a large water source for cooling. Reactors are often placed on the coast because that's a good source of water.

If you only design for a hundred year event, and there's several hundred reactors, then if your estimate is accurate (they're usually very conservative), that's more than one failure per year.

If we'd followed some advice, we'd never have allowed steam-engines, because their boilers occasionally blow up.

[alancalverd]

With a properly trained crew, the 737Max flights could have been saved;

The MCAS was introduced to remove the need for specific type training for 737-rated pilots. When I bought my first glider I was warned that, having a heavier rear fuselage and better forward visibility than the previous model, you needed a lot of nose-down trim and awareness of your angle of attack to prevent stalling at the top of the launch. No problem, standard type conversion briefing. Same could have been done for the 737MAX, rather than install one more thing that could go wrong.

[charles1948]

With a properly trained crew, the 737Max flights could have been saved;

The MCAS was introduced to remove the need for specific type training for 737-rated pilots. When I bought my first glider I was warned that, having a heavier rear fuselage and better forward visibility than the previous model, you needed a lot of nose-down trim and awareness of your angle of attack to prevent stalling at the top of the launch. No problem, standard type conversion briefing. Same could have been done for the 737MAX, rather than install one more thing that could go wrong.

Wasn't the basic problem, that Boeing tried to stretch and extend an old airplane - the 737 - instead of designing a new one.

[Petrochemicals]

You design each station for the 100 or 1000 year event at that site. AFAIK that does not include tsunamis on the UK or French coasts.

Which means that in 1000 years every nuclear reactor in the world  will have poisoned an area the size of belgium?

They should be designed for a timescale equal to the radioactivity, that would be worldwide. Tsunamis are common in a 1000 year timescale

https://en.m.wikipedia.org/wiki/1755_Lisbon_earthquake

Fukushima was designed for a once in 50 year timescale

https://www.worlddata.info/asia/japan/tsunamis.php

[alancalverd]

The design life of a nuclear power station is rarely more than 20 years. Most seem to last longer, but subject to major upgrade if not dismantling and demolition.

Given that the halflife of some fission products exceeds 250,000 years, and the fact that no manmade structure has survived half as long, your preferred timescale is unrealistic.   

[Petrochemicals]

The design life of a nuclear power station is rarely more than 20 years. Most seem to last longer, but subject to major upgrade if not dismantling and demolition.

Given that the halflife of some fission products exceeds 250,000 years, and the fact that no manmade structure has survived half as long, your preferred timescale is unrealistic.   

So nuclear meltdowns all round? That is not a solution

[alancalverd]

On the contrary.

There are currently around 440 operating nuclear power reactors, the oldest being 52 years old, with 3 major incidents of which only Chernobyl resulted in more than 10 attributable deaths. Compare this with an average of 50 deaths per year in coal mines in the USA alone over the last 50 years (and this in probably the most unionised and safety-conscious country of all) and you can see why nuclear power is regarded as safe.

The most telling statistic is the 16,000 deaths caused by the tsunami that damaged Fukushima and almost completely ignored by the world's press. Water is dangerous.

[Petrochemicals]

On the contrary.

There are currently around 440 operating nuclear power reactors, the oldest being 52 years old, with 3 major incidents of which only Chernobyl resulted in more than 10 attributable deaths. Compare this with an average of 50 deaths per year in coal mines in the USA alone over the last 50 years (and this in probably the most unionised and safety-conscious country of all) and you can see why nuclear power is regarded as safe.

The most telling statistic is the 16,000 deaths caused by the tsunami that damaged Fukushima and almost completely ignored by the world's press. Water is dangerous.

Sorry Alan but chernobyl poisoned a huge area, it caused only 4000 deaths because of the luck of the wind direction. If the wind blew toward Kiev we could be looking at over 1 million. Plus the fact that in 50 years of nuclear generation a huge area of land in 2 locations is now inaccessible.

[alancalverd]

Which is why you shouldn't deliberately ignore the operating manual. That's nearly two whole days' worth of COVID deaths in Brazil,  a quarter of the number of people drowned by the Fukushima tsunami, or 30% more than were killed on 9/11. The difference being that none of these other events ever had an intended upside like actually supplying electricity.

[Petrochemicals]

Which is why you shouldn't deliberately ignore the operating manual. That's nearly two whole days' worth of COVID deaths in Brazil,  a quarter of the number of people drowned by the Fukushima tsunami, or 30% more than were killed on 9/11. The difference being that none of these other events ever had an intended upside like actually supplying electricity.

Lucky so far, Kiev is an area of 5 million people. But does not poison even 1 percent as much land, for not 1 percent of the time, does not build radio nucleides in the environment. The fear of Nuclear war was not just the bombs but the Fallout.

[wolfekeeper]

Given that the halflife of some fission products exceeds 250,000 years, and the fact that no manmade structure has survived half as long, your preferred timescale is unrealistic.   

Those aren't the half lives that are the most problematic. The long half life species decay very slowly and so give off very little radiation over a very long period. And the very short half life species decay rapidly and are soon gone; just keep out of their way for a while. No, it's the intermediate ones, that have a half life roughly comparable to human life spans that are the main problem, they give off large amounts of radiation for annoying lengths of time.

For example caesium 137 (30 year half life) and tritium (11 year half life). You don't want to get them inside you or be near them.

[Bored chemist]

Given that the halflife of some fission products exceeds 250,000 years, and the fact that no manmade structure has survived half as long, your preferred timescale is unrealistic.   

Those aren't the half lives that are the most problematic. The long half life species decay very slowly and so give off very little radiation over a very long period. And the very short half life species decay rapidly and are soon gone; just keep out of their way for a while. No, it's the intermediate ones, that have a half life roughly comparable to human life spans that are the main problem, they give off large amounts of radiation for annoying lengths of time.

For example caesium 137 (30 year half life) and tritium (11 year half life). You don't want to get them inside you or be near them.

Yes and no.

If you are looking at long term storage of waste, the intermediate  half life ones are less of an issue.
Things like 90Sr will decay a thousand fold over a period  roughly the same as St Paul's Cathedral has lasted- so we know how to build a structure that will contain them.

It's the hundred-year and up half lives we aren't so sure about. We have some thousand-year-old buildings, but not many

Also, tritium ( decay half life 12.32 years) isn't much of a problem because it doesn't stay in the body.
https://en.wikipedia.org/wiki/Biological_half-life#Water

(And the decay energy is relatively low, so it does less damage)

[alancalverd]

But does not poison even 1 percent as much land, for not 1 percent of the time, does not build radio nucleides in the environment.

I assume you are talking about coal. A relatively minor accident at Aberfan killed 144 people, mainly children, above ground - about the same number as died of acute radiation effects at Chernobyl. Burning coal releases polonium into the atmosphere, and the stuff that comes out of oil wells can really light up the room without burning.

Fact is that however careful you are with coal, it is dangerous, and wind is unreliable. We have to go a long way to replace nuclear power with anything better.

[alancalverd]

Also, tritium ( decay half life 12.32 years) isn't much of a problem because it doesn't stay in the body.
https://en.wikipedia.org/wiki/Biological_half-life#Water

(And the decay energy is relatively low, so it does less damage)

Not quite. The low energy betas have a very short range in tissue so actually cause a lot of damage in a few cells - it's as nasty as many alpha emitters, and the Environment Agency get very exercised about it.

[Bored chemist]

Not quite. The low energy betas have a very short range in tissue so actually cause a lot of damage in a few cells - it's as nasty as many alpha emitters,

A high energy beta particle, on the way to becoming "just another electron", will always pass through a stage of being a low energy beta.
So it will always do more damage.

If the EA don't know that, feel free to tell them.

[Petrochemicals]

Given that the halflife of some fission products exceeds 250,000 years, and the fact that no manmade structure has survived half as long, your preferred timescale is unrealistic.   

Those aren't the half lives that are the most problematic. The long half life species decay very slowly and so give off very little radiation over a very long period. And the very short half life species decay rapidly and are soon gone; just keep out of their way for a while. No, it's the intermediate ones, that have a half life roughly comparable to human life spans that are the main problem, they give off large amounts of radiation for annoying lengths of time.

For example caesium 137 (30 year half life) and tritium (11 year half life). You don't want to get them inside you or be near them.

I understand what you are saying viz a vi's zapping radiation but it is usually if you injest these particles that they are the greatest threat. Plutonium has an very long half life, if on the skin it can be washed off, if injested it is pretty much lethal.

[alancalverd]

Plutonium is a real bugger because it is chemically active, forms compounds with pretty much anything, so can accumulate in bones instead of being excreted, and emits α particles that do massive damage in a short distance, at least 20 and possibly 200 times more biologically damaging than the same dose of γ radiation.   

The practical problem with α and low-energy β radiation isn't shielding from them (a sheet of paper will stop almost all α's) but detecting them in order to prevent or locate ingestion. Never mind needles, you can have a haystack of Pu or Th and not know about it unless you have reason to suspect its presence and something a bit smarter than your average geiger counter to detect it.

[wolfekeeper]

The long half life species decay very slowly and so give off very little radiation over a very long period. And the very short half life species decay rapidly and are soon gone; just keep out of their way for a while. No, it's the intermediate ones, that have a half life roughly comparable to human life spans that are the main problem, they give off large amounts of radiation for annoying lengths of time.

For example caesium 137 (30 year half life) and tritium (11 year half life). You don't want to get them inside you or be near them.

I understand what you are saying viz a vi's zapping radiation but it is usually if you injest these particles that they are the greatest threat. Plutonium has an very long half life, if on the skin it can be washed off, if injested it is pretty much lethal.

There's several isotopes, Pu 238 and Pu 241 have half lives of 87.74 and 14 years respectively, and I'm pretty sure those are the problematic ones. As I say, the ones with half lives comparable to human lifespans are the main issue.