A structural component is fabricated from an alloy that has a plane-strain fracture toughness of 50 MPa√m. It has been determined that this component fails at a stress of 225 MPa when the maximum length of a surface crack is 1.2 mm. What is the maximum allowable internal crack length (in mm) without fracture for this same component exposed to a stress of 225 MPa and made from another alloy that has a plane strain fracture toughness of 30 MPa√m ?