NISA also said it discovered that on March 18, an unusually high amount of radiation was found emanating from a building housing turbines located near reactor No. 2. Although the NISA said the radiation amount was approximately 500 millisieverts per hour, Tepco later denied that such a high level was detected, citing a miscommunication between the plant operator and the NISA.

The NISA said that while they were still unsure of the radiation's source, two workers who were in the building replacing motors for pressure pumps were exposed and further work at that location has been stalled.