Radiation levels on the edge of the plant compound briefly spiked at 8217 microsieverts per hour but later fell to about a third that. A normal year of radiation will be experienced in one day.
Confirmation of loud sounds at unit 2 this morning came from the Nuclear and Industrial Safety Agency (NISA). It noted that “the suppression chamber may be damaged.” It is not clear that the sounds were explosions.
Also known as the torus, this large doughnut-shaped structure sits in the centre of the reactor building at a lower level than the reactor. It contains a very large body of water to which steam can be directed in emergency situations. The steam then condenses and reduces pressure in the reactor system.
The pressure in the pool was seen to decrease from three atmospheres to one atmosphere after the noise, suggesting possible damage.