Tokyo Electric Power Co. has resumed checking the exterior of reactor 2 at its crippled Fukushima No. 1 nuclear power complex by using a tetrapod robot, but the utility has not been able to determine areas where water continues to leak.
The investigation had stalled after the remote-controlled robot, developed by Toshiba Corp., confronted a number of problems in its previous December check — including when it lost its balance while climbing steps.
On Tuesday, Tepco sent the robot near the doughnut-shaped suppression pool at the bottom of reactor 2′s primary containment vessel. It examined areas near some of the huge pipes that connect the pool and the containment vessel.
The probe is part of preparations to eventually remove melted nuclear fuel from the crippled reactor.
Water injected to cool the reactor is currently leaking outside to the reactor building, and Tepco wants to plug the leaks so it can fill the containment vessel with water, which will serve as a shield for radiation before it begins the process of removing the melted nuclear fuel.
But Tepco said Tuesday’s probe could not determine where the leaks are occurring. The utility plans to continue checking areas around the pipes that the robot has not yet probed.
The suppression pool is meant to hold cooling water used in emergencies and is also used to reduce pressure inside the reactor’s primary container.