The other two UPS systems functioned correctly, surviving the overvoltage, probably due to an undetermined subtle difference in wiring or equipment between the two pairs of units.

Though a number of options remained to operators, had further equipment failed, a single cause (one short-circuit) leading to such a cascade of failures was seen as a challenge to the principle of redundancy and safety in depth.

Lars-Olov Höglund, a former construction chief at Vattenfall, claimed it was the most serious nuclear incident in the world since the Chernobyl disaster and it was pure luck that prevented a meltdown.

[7] Both the SKI and the safety chief of Forsmark power plant disagree with that opinion and state that the incident was serious but the description provided by Höglund was incorrect and there was no real risk of a meltdown.

[9] On March 14, 2011, Höglund commented that the Fukushima-disaster parallels the Forsmark incident, i.e. failing UPS system backup, and repeated his statement from 2007 that "only luck" prevented a meltdown at the Swedish plant.

In January an internal report made by a few employees at Forsmark who were concerned over a "degrading safety culture" was leaked to media who ran an extensive story on it.

On January 17, the Swedish Security Service took over an investigation into unauthorized drones seen flying over Forsmark and the Oskarshamn and Ringhals nuclear plants.

[14] In June 2010, Greenpeace activists invaded Forsmark to protest the then-plan to remove the government prohibition on building new nuclear power plants.

A 2018 study found that the area of Forsmark, whose surface belongs to the Sub-Cambrian peneplain, lost 2 to 3 meters of crystalline bedrock due to erosion during the last glaciation.