In 1957, in an English seaside town, a new type of disaster occurred when a fire broke out at the Windscale nuclear reactors. The fire, at the two-reactor facility in Cumbria (now Sellafield), was due to poor design and gross mismanagement, leading to deadly consequences. The incident became embroiled in Cold War-era secrecy and proved the desperate lengths the British government was willing to go to become a global nuclear power.
The origins of the Windscale nuclear fire can be found within the decades long Cold War, specifically the nuclear arms race. Most nuclear projects in Britain and the U.S. were focused on deterring attacks from the Soviet Union, who were also building up their own massive nuclear arsenal.
For the UK, having nuclear bombs was not just about Soviet deterrence; but also about Britain remaining a world power. Following World War II, Britain’s empire and global influence was in steady decline. It needed to prove itself capable of making atomic weapons by itself. It was under these political pressures that construction of the Windscale reactors began.
At the start of the 1950s, Britain built two nuclear reactors, then referred to simply as ‘Piles’, at the Windscale Works in Cumbria on the northwestern coast of England. The reactors were not built to produce electrical power, but rather plutonium-239 for use in nuclear weapons. Each reactor was fueled by 180 metric tons of uranium with 2,000 tons of graphite moderators. In 1952, the British government put the completed Windscale Piles online.
However, several factors had complicated the design and construction process.
The Windscale Piles were planned and constructed far too rapidly. The reactor’s chimneys were partly complete when Sir John Cockcroft, Director of the atomic energy regulator, insisted that radioactive particle filters be added in case of an accident. By then, filters could only be added on top, rather than within the chimneys where they needed to be.
Another issue was that this new nuclear technology was not perfectly understood by the scientists who designed it. The relatively low temperatures at which the Piles were operating caused a build-up of “Wigner Energy,” which could increase temperatures in the reactor if allowed to accumulate. When the engineers finally noticed the problem, their only available solution was to heat the Piles hotter than normal to help release the energy. This process, called ‘Annealing,’ seemed to work.
The reactors were built with an air-cooling, rather than the typical water-cooling, system of most nuclear reactors. This increased the possibility of radioactive air being blown out onto the unsuspecting English countryside. Filters were added at the insistence of John Cockcroft, but at the wrong location on the chimneys.
Other corners were cut to save money and produce plutonium faster than the Piles were capable of safely producing. Windscale was plagued with safety concerns from the start, due to the tight deadlines and time constraints ordered by the British government, who wanted atomic bombs ASAP.
In 1957, the UK faced its worst nuclear power accident in history.
In October, a fire broke out in Windscale’s Pile 1 while it was being routinely “annealed.” When the process was initiated on October 8th, the pile failed to get warm enough to regulate the Wigner energy levels in the graphite moderators. Wigner energy increases because of the displacement of carbon atoms in the graphite lattice. This energy needed to be regularly annealed through the heating process that released the energy.
When the process was tried again the next day, October 9th, the pile became sufficiently hot (uranium temperature of 250 C), but strangely stayed hot. Then as the staff watched in shock, the temperature reading within the Reactor 1 began to rise and rise. It reached an alarming 400 C, the hottest the reactor had ever reached. Air fans failed to cool down the pile.
On October 10th, the site engineers realized in horror what was happening. The interior of the reactor now glowed with heat. A protective aluminum cannister had burst inside Pile 1 allowing the uranium to catch file. Uranium fuel cartridges were now incredibly hot. Engineers discovered flames at the back of Pile 1!
The reactor’s engineers and operators frantically made several different efforts to fight the fire. First, they attempted to knock the burning uranium away manually using long metal poles. Then carbon dioxide was pumped into the pile in an attempt to smother the flames. Neither strategy had an effect.
On October 11th at 9 AM, water was turned on, with the flow increased through the day from an initial flow of 300 gallons per minute, to 800 gal/min, to 1,000 gal/minute by Noon. The water flow continued until the next day, October 12th with no effect. Finally, the engineers closed off the airflow to the reactor and the fire died out. The reactor slowly cooled down to a stable temperature and everyone in the control room breathed a heavy sigh of relief.
Windscale had released radioactive debris into the English atmosphere for four days.
It became the worst accidental release of radioactive materials in British history. Local residents in nearby Nethertown, Gosforth and Seascale were not evacuated or even notified that a facility fire was taking place, There were left in the dark and therefore exposed to radiation. Fortunately, Cockcroft’s filters, nicknamed “Cockcroft’s follies” at the time, had prevented the impact from being far worse.
Following the fire, environmental measurements were taken to determine the spread of radiation. Measurements showed atmospheric dispersion of radioactive materials throughout England, Wales and parts of northern Europe with the highest concentrations to be I-131 and Cs-137. Of the two, the bigger focus was on the I-131 as the most hazardous consequence of the fire.
The most visible action at the time, and the only one the government acknowledged, dealt with milk contamination. Despite fears over the potential cancer risks posed to locals, especially children, the main course of action taken was the destruction of around 250,000 gallons of milk from farms within 300 square miles of the facility.
After radioactive iodine-131 particles were released into the air, they fell onto farmland grasses and were eaten by dairy cows. The milk produced would then contain enough radioactive iodine to raise the risks of thyroid cancer, especially in children who drank it. Further, the government banned sales of milk from within 200 square miles of Windscale, but for only a month.
Other than this, the government insisted the population need not worry. In fact, radioactive particles had spread across the northern UK and eastward over Europe. The disaster would later be rated Level Five on the seven-point International Nuclear Event Scale – the same as the USA’s Three Mile Island disaster.
The British government downplayed the accident. The government’s report on the fire was deemed unpublishable due to the secrecy risk it posed. Harold Macmillan, then UK Prime Minister, mandated that only the summary of the report be published. British nuclear physicist Sir William Penney’s report on the incident was censored and blamed the staff. The pile operators had resorted to shaving down the protective fins of the aluminum cartridges that housed the uranium to increase yield.
The Windscale Piles closed for good.
The members of government, who had ignored safety risks by putting pressure on the factory to produce plutonium faster, were quick to shift blame to the Pile operators. An investigation by Sir Alexander Fleck prompted the 1971 creation of the National Radiological Protection Board (NRPB). The Windscale site, renamed Sellafield in the 1980’s, has continued to host energy generation and waste management since.
Recent reports have concluded that the fire was ultimately caused by the project’s emphasis on speed and output over safety. It was not until the late 1980s, 30 years later, that relevant documents were declassified and made available. In 1990, the director of the UK’s National Radiological Protection Board estimated that the fire had likely caused about 100-240 local deaths from cancer, in addition to countless non-fatal cancers. It was a high price to pay for the Cold War arms race.
For decades, Pile 1 remained sealed away, unused though monitored. In recent years, a slow process of decommissioning has begun including clean-up of the fire’s effects. In 2021, the government announced that it had demolished Pile 1’s infamous chimneys. Spent fuel also needs to be treated and stored. The target date for completing all decommissioning activities at Sellafield is 2040.
It can be argued that 20th century governments, 75 years ago, believed that the benefits justified the risks. However, in cases like Windscale and later Chernobyl, the politics of the Cold War encouraged governments on either side to take fewer cautions against the public health risks posed by their nuclear projects.
In a post-Chernobyl/Fukushima world, it seems horrifying that governments would have such a careless reaction, but in the 1950s, many countries downplayed or covered up the environmental and health risks posed by their nuclear programs. Both Windscale and Chernobyl were operating with poor designs; pressure for fast results; and with safety risks accepted as a means of rushing timelines and, of course, saving money.