Samsung Electronics and SK Hynix have rejected Korea Electric Power Corp.'s proposal to prepay a combined 25 trillion won, or $18.7 billion, to support electricity infrastructure for planned semiconductor mega clusters. A document submitted to lawmaker Lee Chul-gyu showed the companies told the state-run utility after internal reviews that accepting the arrangement would be difficult. An official familiar with the matter said the companies questioned whether such large upfront payments were necessary amid uncertainty over the long-term durability of semiconductor demand. Samsung's proposed contribution was 20 trillion won and SK Hynix's was 5 trillion won, based on projected 2025 electricity consumption. KEPCO planned to use the funds for transmission and substation construction serving facilities in Yongin and the Honam region, which are expected to require multiple gigawatts of power capacity. The arrangement would have allowed the heavily indebted utility to finance construction without immediately increasing its borrowings, while recovering principal and interest through future electricity bills. The rejection leaves uncertainty over how and when grid connections for the planned fabs will be financed and completed. SK Hynix has separately announced plans to invest 54.3 trillion won in two memory-fabrication facilities targeting demand for high-bandwidth memory and other advanced chips.