Japan's nuclear regulator has decided to request that the operator of the crippled Fukushima Daiichi nuclear power plant immediately study the possible impact of recently identified damage to one of the reactors and compile necessary countermeasures.
Three reactors of the plant suffered meltdowns in the 2011 earthquake and tsunami.
In March, the plant's operator Tokyo Electric Power Company conducted investigations of the interior of the containment vessel of the No.1 reactor using an underwater robot. TEPCO said the pedestal, a cylindrical concrete structure supporting the reactor, is damaged almost all the way around, leaving the steel reinforcing rods exposed.
The Nuclear Regulation Authority held a meeting on Wednesday to discuss the findings reported by TEPCO last month.
TEPCO said in the report that even if the pedestal becomes unable to support the reactor, other surrounding structures would prevent the reactor from collapsing entirely.
The regulator decided at the meeting to call on TEPCO to study possible risks in case that the pedestal becomes unable to support the reactor. It will also ask the utility to draw up necessary measures to prevent the possible spread of radioactive materials outside the reactor. The regulator will request that TEPCO compile those risks and measures by July.
A participant of the meeting said that the situation cannot be regarded as optimistically as TEPCO explained. Another expressed concern over possible further damage to the containment vessel and said it is necessary to swiftly compile countermeasures.
Separately, TEPCO plans to study further whether the damage could undermine the reactor's quake resistance.