日本原子力研究開発機構
The Japan Atomic Energy Agency initially rated the Unit 1 situation as below both of these previous accidents; on 13 March it announced it was classifying the event as Level 4, an "accident with local consequences". On 18 March it raised its rating on Units 1, 2 and 3 to Level 5, an "accident with wider consequences". It classified the situation at Unit 4 as a Level 3 "serious incident".