Windscale 1957: Worst-case scenarios

The Accident:
The fire at the Windscale nuclear facility in 1957 still remains as one of the most serious disasters in the history of atomic energy, and whilst now it has been overshadowed in fame by Chernobyl, Three Mile Island and Fukushima Daiichi it stands as easily the worst nuclear catastrophe in the United Kingdom and Western Europe as a whole. The first of the two graphite-moderated reactors (or 'piles') - which were being used recklessly in a last-ditch attempt to shore up the struggling British atomic weapons programme - came close to utter disaster when a fire in one of the reactor core channels was misinterpreted and the plant workers inadvertently fed the conflagration using the fans ironically used to keep the reactor cool. Despite trying to create a firebreak in the reactor by forcing out fuel rods and trying to use carbon dioxide to quell the flames, it seemed that the fire would seemingly burn out of control.

The Reactor Manager, Tom Tuohy (who lived to the ripe old-age of 90 despite his significant radiation exposure), was then faced with a do-or-die situation; with eleven tonnes of uranium ablaze inside the reactor and temperatures stretching into the extreme limits of the reactor building itself (one thermocouple registering 1300 °C above the 'white hot' reactor channels), he suggested that water be flooded into the reactor. The possibility of the molten metal oxidizing with the water, creating free hydrogen, left the risk of a colossal explosion and the complete detonation of the reactor building. When this did not happen (but the flames continued to burn), Tuohy ordered everybody out of the reactor building and turned off the huge fans that continued to push oxygen into the fire. It stopped almost immediately.

According to Wikipedia, the fire released an estimated 740 terabecquerels of iodine-131, as well as sizeable amounts of caesium-137, xenon-133 and other radionuclides. Later reworkings of affected areas have shown the amounts released may have been higher. Iodine-131 was of particular concern as whilst it has a half-life of barely more than week it can be absorbed by the body and trigger the formation of thyroid cancers - estimates of those affected are controversial and varied. Milk from the surrounding area was ditched into the Irish Sea for a month, and nowadays there are generally acknowledged to have been minimal health effects even upon those with the highest exposure rates.

The Worst-Case Scenarios
I think it can be stated comfortably that whilst the Fire was a very serious event, it generally was a near-miss. However, I am keen to find out any potential information I can about the consequences of the situation in Cumbria going disastrously wrong. I have a few circumstances in which this could have happened.

  1. What if the chimney filter - known as 'Cockcroft's Folly' - had not been installed? What would have been the levels of radiation release if the material had been able to shoot straight out of the chimney as a result of the fire? (For my own purposes, this is less useful as it requires a PoD somewhere during the construction of the plant).
  2. In my opinion, the greatest scope for disaster stems from a potential explosion as a result from the flooding of the reactor with water. If the molten metal in the core did react to create free hydrogen and detonated, the weakened reactor building would have simply ceased to exist. Poor Tom Tuohy, standing on the top of the reactor, would have been vaporized. If the reactor exploded in such a dramatic way, what would be the extent of the physical damage on the ground and what would have been the radiation consequences for Western Europe? In the well-known BBC documentary, Lorna Arnold (from the UKAEA) suggested the whole plant and most of Seascale would have been completely flattened. Is this game over for Cumbria at least?
  3. Finally, what would the consequences be if the fire simply was left to burn? For whatever reason the flames continue to be fed by the fans, and with no other option evacuation efforts are conducted. How long would the fire last and what would happen to the plant?
As an aside, would it be possible to discover after the event - simply from the fallout and physical evidence - that the Windscale plant was producing weapons-grade material rather than civilian energy? I have no idea.

There are a wide array of political consequences from the Fire, even in our timeline, so the ramifications for the British and Western Europe geopolitical situation could - and likely will be - very significant. I would be very interested to hear your thoughts and hopefully gain some more precise statistics as to predicted radiation levels across Europe.
 
A friend has done work at Sellafield. I dont think he worked on the Follies but I will ask him tonight and see if he can come to the forum with some first hand info. He did tell me that one of the isotopes that could have been released in a big worst case explosion would have meant building a wall round a major chunk of the Lake District and forgetting about it for a few hundred years.
 
A friend has done work at Sellafield. I dont think he worked on the Follies but I will ask him tonight and see if he can come to the forum with some first hand info. He did tell me that one of the isotopes that could have been released in a big worst case explosion would have meant building a wall round a major chunk of the Lake District and forgetting about it for a few hundred years.
Thanks. Sounds like an interesting bloke and I'd be really interested to hear about his views.
 
I'm not equipped to give precise answers, but we can put a few bounds on things. Generally speaking, the radioisotope content of a nuclear reactor is roughly proportional to its thermal power output, everything else being equal. The Windscale piles were 180 MWth thermal power output. For comparison, the Chernobyl reactors had a thermal power output of 3,200 MWth. So we're looking at roughly 6% of a Chernobyl.

As an aside, would it be possible to discover after the event - simply from the fallout and physical evidence - that the Windscale plant was producing weapons-grade material rather than civilian energy? I have no idea.

As far as I'm aware, nobody ever claimed that the Windscale piles were for civilian energy. They weren't even hooked up to turbines, so it would be a bit difficult to claim they were generating electricity.

A friend has done work at Sellafield. I dont think he worked on the Follies but I will ask him tonight and see if he can come to the forum with some first hand info. He did tell me that one of the isotopes that could have been released in a big worst case explosion would have meant building a wall round a major chunk of the Lake District and forgetting about it for a few hundred years.

Radio-cesium, most likely.
 
For comparison, the Chernobyl reactors had a thermal power output of 3,200 MWth. So we're looking at roughly 6% of a Chernobyl.

But there were four reactors, just one had the accident, so closer to 11.25%, with one reactor burning with Windscale. But that fire produced about 2% of the Xenon-133 that Chernobyl did,.
and the Cesium-137 was a fraction of that.
 
Generally speaking, the radioisotope content of a nuclear reactor is roughly proportional to its thermal power output, everything else being equal. The Windscale piles were 180 MWth thermal power output. For comparison, the Chernobyl reactors had a thermal power output of 3,200 MWth. So we're looking at roughly 6% of a Chernobyl.
Thanks. That's a handy way of looking at it. By '6% of Chernobyl' do you mean the amount of energy or radiation released? I assume you mean the dirty stuff.
As far as I'm aware, nobody ever claimed that the Windscale piles were for civilian energy. They weren't even hooked up to turbines, so it would be a bit difficult to claim they were generating electricity.
There was already quite an amount of controversial within the scientific community at Windscale that the plant was operating way above what it was designed for; after the fire in OTL there was a pretty decent cover-up by the Macmillan government in the hope that news of the incident wouldn't throw the imminent sharing of Anglo-American atomic secrets under the bus. I think that if the incident was worse, the government would do all it could to try and disguise the fact it had essentially irradiated Cumbria in a desperate struggle to build a bigger bomb. A civilian disaster is one thing - a military one, I think, would be hard less palatable by the public. Especially on this scale. If there was an explosion you'd expect that quite a sizeable amount of the plant would have been blown up (and inaccessible due to the radiation) so I think a cover-up is likely.

There were four reactors, just one had the accident, so closer to 11.25%, with one reactor burning with Windscale. But that fire produced about 2% of the Xenon-133 that Chernobyl did,
and the Cesium-137 was a fraction of that.
That is indeed true in the case of the OTL fire, but if the flooding of the reactor caused the detonation of the plant surely the other Pile would be in severe trouble. Probably even Calder Hall too. Even then, there is going to be a lot burning at the site and the situation would surely escalate out of control for at least a while. So I think that an estimate on the heavier side of irradiation could be justified.

Great Britain's Chernobyl?
Probably not on that scale, depending on the disaster, but in my opinion the Windscale Disaster could be just as devastating; Chernobyl, whilst catastrophic, was ultimately in the middle of a relatively-sparsely-inhabited part of Eastern Europe partly shielded from the view of the West by the incognito atmosphere of the Eastern bloc. A comparable disaster happening within the densely-populated British Isles (as obviously Ireland and the Isle of Man are also going to be significantly affected by this) is a pretty big deal.
 
But there were four reactors, just one had the accident, so closer to 11.25%, with one reactor burning with Windscale. But that fire produced about 2% of the Xenon-133 that Chernobyl did,.
and the Cesium-137 was a fraction of that.

I'm not sure where you're getting the 11.25% number? While there were four reactors at the Chernobyl plant, only one was lost - in fact, the other three were kept in use for years after the accident.

Thanks. That's a handy way of looking at it. By '6% of Chernobyl' do you mean the amount of energy or radiation released? I assume you mean the dirty stuff.

The amount of fallout released. That's a very inaccurate estimate, but it's the best we can do without the sort of work that's beyond the scope of an AH.com thread. The total fallout is actually going to be proportional to the energy output since the reactor started its run, that is:

(Thermal Power Output) * (Time Since Last Refueling)

But I don't know where to find the time since last refuel for either Windscale or Chernobyl, and thermal power output is a "good enough for AH.com" estimate.

There was already quite an amount of controversial within the scientific community at Windscale that the plant was operating way above what it was designed for; after the fire in OTL there was a pretty decent cover-up by the Macmillan government in the hope that news of the incident wouldn't throw the imminent sharing of Anglo-American atomic secrets under the bus. I think that if the incident was worse, the government would do all it could to try and disguise the fact it had essentially irradiated Cumbria in a desperate struggle to build a bigger bomb. A civilian disaster is one thing - a military one, I think, would be hard less palatable by the public. Especially on this scale. If there was an explosion you'd expect that quite a sizeable amount of the plant would have been blown up (and inaccessible due to the radiation) so I think a cover-up is likely.

This is not going to be disguised as a civilian disaster. They'd never concealed the fact that these reactors were for making bombs, and now one has blown up. How do you conceal that?

That is indeed true in the case of the OTL fire, but if the flooding of the reactor caused the detonation of the plant surely the other Pile would be in severe trouble. Probably even Calder Hall too. Even then, there is going to be a lot burning at the site and the situation would surely escalate out of control for at least a while. So I think that an estimate on the heavier side of irradiation could be justified.

The other pile might be okay, it's tough to say. Reactors - even badly-designed ones like Windscale - are tough beasts.
 
I'm not sure where you're getting the 11.25% number? While there were four reactors at the Chernobyl plant, only one was lost - in fact, the other three were kept in use for years after the accident.

Windscale((Thermal power*(failed reactors/total reactors)) / Chernobyl((Thermal power*(failed reactors/total reactors))

But I don't know where to find the time since last refuel for either Windscale or Chernobyl, and thermal power output is a "good enough for AH.com" estimate.

Windscale was continually refueled, as one new slug was inserted, a hot, radioactive slug was pushed out into the cooling pond.
except then they didn't slide out right, and workers had to manually push them into the Pond as they piled up on the side of the housing.

Yeah, great design there.

Not even the first Soviet reactors were that shoddy.
 
Windscale((Thermal power*(failed reactors/total reactors)) / Chernobyl((Thermal power*(failed reactors/total reactors))

You're assuming both reactors fail catastrophically, which I don't think is necessarily going to be the case.

Windscale was continually refueled, as one new slug was inserted, a hot, radioactive slug was pushed out into the cooling pond.

Which means that, for the purposes of calculating the damage, we need to find the average length of time that each slug was in the reactor. Plus we need equivalent data from Chernobyl. Or we can do it from first principles with fission product inventory.

Or, at least, someone can - I don't have the time.

except then they didn't slide out right, and workers had to manually push them into the Pond as they piled up on the side of the housing.

Yeah, great design there.

Not even the first Soviet reactors were that shoddy.

At least Windscale didn't have a positive void coefficient.

Honestly, all of the early plutonium piles were pretty awful. The big difference was that the US and UK learned from what they did. The USSR doesn't seem to have.
 
A friend has done work at Sellafield. I dont think he worked on the Follies but I will ask him tonight and see if he can come to the forum with some first hand info. He did tell me that one of the isotopes that could have been released in a big worst case explosion would have meant building a wall round a major chunk of the Lake District and forgetting about it for a few hundred years.
If it's cesium (the usual worst offender), which it most likely would be (as Asyns says), then we're looking at relocation of the people in the main contaminated area for at least 50 and probably more like about 100 years. A lot of the land could pretty well be cleared up from day one with a little excavation. The Chernobyl area is too big and underpopulated for this to be practical but in Britain, that method of remediation would have been worth the trouble and probably would have been done on a decent scale.
 
I'm not sure where you're getting the 11.25% number? While there were four reactors at the Chernobyl plant, only one was lost - in fact, the other three were kept in use for years after the accident.
Unlike Windscale or even Calder Hall in this scenario, I think.
The amount of fallout released. That's a very inaccurate estimate, but it's the best we can do without the sort of work that's beyond the scope of an AH.com thread. The total fallout is actually going to be proportional to the energy output since the reactor started its run...
Yeah, I appreciate that this thread probably isn't the place to crush the numbers. If somebody does manage to find the time, though, I'd be happy to have a PM about it.
This is not going to be disguised as a civilian disaster. They'd never concealed the fact that these reactors were for making bombs, and now one has blown up. How do you conceal that?
I think Macmillan will try something of the sort. He is never going to convince the Americans that British is a trust-worthy atomic ally again, but he can certainly try to shift as much of the blame away from the higher-ups and down to the workers at the plant. Seeming as most of them will now probably be dead, that is going to prove easier than the white-washing that came in OTL. Nevertheless, there will be a significant public outcry (as a bare minimum). The anti-nuclear movement might get much further much earlier, as I think that the British weapons programme - at least the form it was taking immediately after WW2 - is scuppered totally. I could see Britain trying to join with France or another European power to try and form a joint-programme, but even then that will be a long shot.
The other pile might be okay, it's tough to say. Reactors - even badly-designed ones like Windscale - are tough beasts.
That's true, but this is a thread for worse-case scenarios...
You're assuming both reactors fail catastrophically, which I don't think is necessarily going to be the case.
See above! What if it is both reactors that fail catastrophically? Astronomical odds, or no.

Windscale was continually refueled as while one new slug was inserted a hot radioactive slug was pushed out into the cooling pond - except then they didn't slide out right and workers had to manually push them out. Yeah, great design there.
It could be argued that it was a pretty decent make-do-and-mend design on tight budgets and even tighter schedules. It doesn't justify the risks taken later on though.

We need equivalent data from Chernobyl.
Reading up on it a bit, the facts for Chernobyl are quite readily accessible so that's good.
Or, at least, someone can - I don't have the time.
Well, thanks for commenting thus far!

If it's caesium (the usual worst offender), then we're looking at relocation of the people in the main contaminated area for at least 50 and probably more like about 100 years. A lot of the land could pretty well be cleared up from day one with a little excavation. The Chernobyl area is too big and underpopulated for this to be practical but in Britain, that method of remediation would have been worth the trouble and probably would have been done on a decent scale.
As I mentioned in my OP, a source from the UKAEA stated that the land would most probably not be in use today. In the immediate periphery of the plant, that is certainly going to be true. The Cumbrian coastal towns are going to go from remote to near-uninhabited in a very short space of time. As a little experiment, I measured what a 30-mile Zone surrounding Windscale would encompass. Not taking geography into account, most of the western Lake District is included and I'd put Windermere as a rough estimate in that direction. In the south, Barrow-in-Furness is also going to be significantly affected but I'm not certain that the town would be cleared; this is just a hypothetical 30-mile radius, but Barrow itself is a pretty major hub in the northwest for civilian and military purposes. Maybe it becomes the headquarters of the Zone of Alienation Authority? If the Disaster is big enough to justify just a zone (even if just for the first few years), both Ireland and the Isle of Man could also be nastily affected. This partly depends on both wind-speed and direction. Either way, the Irish Sea is going to face some pretty severe challenges.
 
As I mentioned in my OP, a source from the UKAEA stated that the land would most probably not be in use today. In the immediate periphery of the plant, that is certainly going to be true. The Cumbrian coastal towns are going to go from remote to near-uninhabited in a very short space of time. As a little experiment, I measured what a 30-mile Zone surrounding Windscale would encompass. Not taking geography into account, most of the western Lake District is included and I'd put Windermere as a rough estimate in that direction. In the south, Barrow-in-Furness is also going to be significantly affected but I'm not certain that the town would be cleared; this is just a hypothetical 30-mile radius, but Barrow itself is a pretty major hub in the northwest for civilian and military purposes. Maybe it becomes the headquarters of the Zone of Alienation Authority? If the Disaster is big enough to justify just a zone (even if just for the first few years), both Ireland and the Isle of Man could also be nastily affected. This partly depends on both wind-speed and direction. Either way, the Irish Sea is going to face some pretty severe challenges.

It really also depends a lot on the willingness of people to tolerate the risk of living in contaminated areas and the level of contamination deemed acceptable in the long term.
 
It really also depends a lot on the willingness of people to tolerate the risk of living in contaminated areas and the level of contamination deemed acceptable in the long term.
In the immediate aftermath of a disaster, I can see the government enforcing evacuations to minimize the threat to the public. For many farms in the hills, this could be spell disaster as their livestock are essentially written off and possibly slaughtered. The larger towns aren't going to be empty, sure, and I think Barrow is probably far enough away to be habitable after not too much time. That coast is going to be even more barren than it is now though.
 
When thinking about radiation releases I always recall that any coal fired power station of equivalent power would be shut down instantly if it had to meet the same standards. When hundreds of thousands of tons of coal go through a conventional power station the coal may have very tiny amounts of assorted radioactive items but the aggregates are huge. Plutonium by the kilo, uranium in far larger amounts all freely released into the air. People do not fear living and working in radon laden granite towns like Aberdeen but radioactivity is no less dangerous just because it is natural. Many natural foods would be banned were they newly invented: cyanide in potatoes, toxic defensive chemicals in cabbages, radiation in Brazil nuts......

It doesn't diminish the potential scale (no pun intended) of this incident but gives a sense of proportion and we live with varying 'natural' radiation all the time.
 
Many natural foods would be banned were they newly invented: cyanide in potatoes, toxic defensive chemicals in cabbages, radiation in Brazil nuts......
It doesn't diminish the potential scale (no pun intended) of this incident but gives a sense of proportion and we live with varying 'natural' radiation all the time.
That is true, but food doesn't release a fatal dose all at once. A site I have just found via Google has told me that it would require 46,000,000 bananas to kill a human via radiation. Given that during OTL workers could only spend a few minutes at the face of the reactor when they attempted to clear fuel from inside it, that's some pretty scary stuff right there. People aren't aware of background radiation because ultimately it doesn't kill you. It is an interesting point to think about though! It's a segue, but an entertaining one.
 
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