Figure 1. Overview of the Fukushima Daiichi complex
The Fukushima Daiichi complex consisted of 6 reactor units of the type generation 2 (Gen II) boiling water reactors (BWR) from the 1960s [1]. The plant, like all nuclear power plants except Chernobyl, was designed with a containment building of the BWR-MARK-1 type [2].
On the day of the accident, units 1, 2, 3 were in operation. Unit 4 was undergoing a fuel change. Units 5 and 6 had been taken out of service for routine maintenance prior to the earthquake [3].
Sources:
- GE BWR – Wikipedia
- https://www.nrc.gov/docs/ML1232/ML12326A344.pdf?fbclid=IwAR3EJGWlfGvivQ0Z9FjaJNUL10SgyuOnzRUJPJFt0S6c7LntLxl9om1JoBQ
- https://www-pub.iaea.org/MTCD/Publications/PDF/AdditionalVolumes/P1710/Pub1710-TV1-Web.pdf?fbclid=IwAR392Q6X9N9_ZpK92gYjm0G8vso50OSYZ05VJeE9l3wdyC5M6ptrK2Na2b8
