South Korea\'s state-run atomic laboratory said Thursday it has developed a nondestructive tester for steel that can penetrate a record 80 millimeters and could be used by shipyards and nuclear reactor builders around the world. The residual stress instrument (RSI) has 20 millimeters more in penetrating capability compared to the ISIS machine made Britain that has been lauded as having the best performance so far, the Korea Atomic Energy Research Institute (KAERI) said Thursday.