The RPV of Central Laguna Verde NPP Unit-1 was very busy with many kind of core access activities, some replacement activities and other routine activities. It was very difficult to perform the inspection under these circumstances but we could execute the inspection successfully.

We also could proof the merit of the AIRIS 21 TM with this field experience such as reduction of the radiation exposure for inspection personnel and reduction of the inspection time.

The AIRIS 21TM was developed by IHI to accomplish the inspection of RPV welds in early stage of nuclear power plants. In early stage of NPP, insufficient consideration was paid to accessibility for inspection personnel, and it was difficult to access to the outside surface of the RPV for inspection.

Periodic access to the RPV's outside surface by inspectors or maintenance personnel was difficult because such work would require them to pass through a high-radiation area or stay there for some period of time, and because it was difficult to reduce the personnel radiation dose.

Our solution to this problem is an underwater inspection robot. It is completely different from that of conventional robots for this kind of purpose.

This new robot performs a non-destructive inspection of welds in the RPV shell from inside. The advantages are significantly reduced inspection time, reduced amounts of radiation exposure for inspectors, and the ability to increase the extent of inspection in hazardous environments.