It is remarkable how France has been getting something like 80% of their power from nukes for decades without any major accidents.
Two close calls (level 4) in 1969 and 1980 (at Saint-Laurent-des-Eaux): https://en.wikipedia.org/wiki/Saint-Laurent_Nuclear_Power_Pl...
1. run everything above the standards without compromise.
2. having a production-independant control organization to monitor that everything is done according to 1. And that has the power to shutdown a plant.
Things might be different this time but it turns out that so far, how you make electricity doesn't have much impact on the cost and human progress. Perhaps a future when there are excesses and scarcity on a minute by minute basis things will be different but we will have to wait and see.
A level 2 on the INES is an Incident. A major Accident would be a level 7.
A level 2 is not that bad : Impact on people and environment: Exposure of a member of the public in excess of 10 mSv. Exposure of a worker in excess of the statutory annual limits. Impact on radiological barriers and control:
Radiation levels in an operating area of more than 50 mSv/h. Significant contamination within the facility into an area not expected by design. Impact on defence-in-depth:
Significant failures in safety provisions but with no actual consequences. Found highly radioactive sealed orphan source, device or transport package with safety provisions intact. Inadequate packaging of a highly radioactive sealed source.