Complex sentence: It was determined that the leak in the cable storage pit by unit 2 was likely due to a faulty joint where the pit meets a duct, leading to a gravel layer beneath, resulting in highly radioactive water pouring directly into the sea.
Split into simpler sentences: It was determined that the leak into the cable storage pit from unit 2 was likely due to a faulty joint where the pit meets a duct. The pit leads to a gravel layer beneath, resulting in highly radioactive water pouring directly into the sea.