How Close Did Windscale Come to a Major Nuclear Disaster?

[Delta Force]

The Windscale Fire seems like it had the potential to become a much more serious incident due to actions taken in trying to get the reactor under control. First the operators ran the air fans at high speed to try to cool the reactor, but that only made the fire even more intense. Then crews injected carbon dioxide into the reactor, but the temperatures were so hot that the fire stripped oxygen from the flames. The reactor was reaching temperatures of up to 1,300 degrees Celsius and at risk of structural collapse when the decision was made to pump water into the core, but even that failed to stop the fire. At that point the reactor building was evacuated except for the Reactor Operator and Fire Chief, who made a successful effort to shut off air flow to the reactor. Although it was later found that the graphite never caught fire, it was severely damaged and the reactor continued to have significant nuclear heat. Even now there are concerns that the reactor could achieve criticality during decommissioning efforts.

Even if the incident itself had failed to progress into something worse, things could have been worse if not for Sir John Cockcroft's insistence that filtration equipment be installed to reduce radiation release in the event of a reactor fire. The Windscale site also hosted a twin production reactor to the one that caught fire, as well as four Magnox reactors, two of which were operational at the time of the fire.

Just how bad could things have gotten at Windscale?

 

[Baluncore]

I assume you are referring to the 1957 fire. Catastrophising about the worst possible outcome, 60 years after it happened is a bit pointless. If the fire had spread within the reactor then there could have been significantly more contamination released. It is also possible that it could have melted down, but probably not become a nuclear explosion. I think it is safe to say that everyone involved did the best they could under the circumstances with the information available. Are you asking what they could have done differently so as to make the situation worse ?

 

[Astronuc]

Just how bad could things have gotten at Windscale?

Had they not turned off the cooling fans, presumably, the fire would have continued and the release of volatile and gaseous fission products would have continued until the fire consumed available fuel. Fortunately, Tom Tuohy made the critical decision to turn off the fans, which cut off the air feeding the flames. The pile design was flawed in the sense that it lacked a fire suppression system, and the operators lacked a plan to preclude a fire in the pile.

https://en.wikipedia.org/wiki/Tom_Tuohy

There was a lot of criticism of the air cooled design, but the British government was in a rush to produce material for their program before some deadlines of international agreements limiting or suspending such activities. One must recognize that Britain and the world had just come out of a brutal world war (WW II) in which new technologies, long range ballistic missiles and nuclear weapons, were introduced. Britain helped the US program, but after being excluded, felt compelled to develop their own program. Indeed, the Soviet Union, and subsequently China, were set on developing their on nuclear capability.

After the war, the Sellafield site was briefly in the ownership of Courtaulds for development as a factory, but was reacquired by the Ministry of Supply to adapt the site for the production of materials for nuclear weapons, principally plutonium, and construction of the nuclear facilities commenced in September 1947. The site was renamed Windscale (after Windscale Nook, a bluff on the north bank of the River Calder) to avoid confusion with the Springfields uranium processing factory near Preston. The building of the nuclear plants at Windscale Works was a huge construction project, requiring a peak of 5000 workers. The two air-cooled and open-circuit, graphite-moderated Windscale reactors (the "Windscale Piles") constituted the first British weapons grade plutonium-239 production facility, built for the British nuclear weapons programme of the late 1940s and the 1950s.

https://en.wikipedia.org/wiki/Sellafield#History

 

[Delta Force]

Are you asking what they could have done differently so as to make the situation worse ?

I'm wondering how bad things could have gotten if Cockcroft's Follies had not been fitted to the reactor, as well as if the water injections could have caused a reactor explosion. At Three Mile Island the operators were very concerned about the hydrogen bubble in the pressure vessel being introduced to oxygen and an ignition source. At Windscale the reactor already had oxygen and an ignition source to which hydrogen was essentially being introduced to through the water injections.