Trino Nuclear Disaster
The Trino nuclear disaster was a power plant meltdown that occurred in the town of Trino, North Italy. The disaster occurred after a series of negligence allowed for nuclear waste to contaminate the Po River, causing a natural phenomenon across Europe.
Italy had performed poorly during the Great War and the World War, the latter of which led to the breakup into North and South Italy. North Italy elected a communist government, and subsequently joined the Comintern Union.
North Italy was seen as a junior member in the Union, with the other members viewing it as little as conquered territory. As such, North Italy wished to increase its prestige on the global scale. It did so by attempting to steal and replicate the success of nuclear power in the German Empire. A small plant was created and opened in 1959 in Ispra as a proof of concept. After that success, the North Italian government approved the construction of a larger one in Trino, which would be completed and opened in 1964. Many changes were made between Ispra and Trino as a means to cut costs.
In 1965, the power plant had an issue, one that the workers were under prepared for. As a result, a series of events occurred that allowed for serious mistakes to be made out of ignorance and the little amount of cooling available to be overwhelmed. After which, the concern escalated into a full meltdown. Water from the Po River was used in order to try and cool the reactor core, but the runoff was allowed to pour into the river. Though it was eventually successful in preventing a nuclear explosion, the river was contaminated.
The contamination of the Po River subsequently poisoned the Po River Basin, the main area for agriculture in North Italy. The river was also a main source of drinking water for the country, and as such polluted most of the towns in the Po Valley. The runoff flowed all the way to the Adriatic Sea, creating "dead zones" in the local environment.
The North Italian government attempted to contain the news of the incident, while at the same time recalling the food that had been produced and sending vague warnings of the drinking water. Eventually, the towns along the Po River were evacuated, with many refugees going to France while others crossed the dangerous border to South Italy. Yugoslavia, reliant on the fishing in the Adriatic Sea, quickly noticed the presence of the "dead zones", demanding an explanation. Yugoslav testing of the sea showed high concentrations of radiation in the northern sector of the Adriatic Sea.
The incident led to a near socio-economic collapse of North Italy. The nation became completely reliant on the other members of the Union for food, causing shortages throughout not only the Comintern, but Europe as well. Meanwhile, the North Italian government, now open about the disaster, spent almost the entirety of their economy on cleaning up from the disaster. North Italy would not recover until 2009. The ruling Commissar of North Italy was replaced, and quietly disappeared, being succeeded by an even more controlling regime.

An excellent layout and top down beginning view of this incident, and I for one cannot wait as the story develops, and the affected players and environmental impacts become more clear in future articles, as well as perhaps some of the key decision makers and policy makers whom ultimately helped contribute to the circumstances that would lead to this disaster. A great broad overview though, and I like we don't have casualty totals or even estimates in an overview from this more top down perspective, that makes sense because the sheer scale and scope of coming up with the numerics to begin even attempting to calculate such things would be an entire effort all its own and likely would result in a much more in depth report about the accident/failure at Trino, likely a document article even perhaps, a deep dive investigation as such. This article truly has so much keystone potential on premise alone, and you laid it out broad, yet the through lines make a lot of sense in the context of the history of this version of earth's events. Very tidy work Tynen, well done :)