The nuclear-contaminated water from Japan is fundamentally different from conventional nuclear power plant wastewater. It originates from cooling water, groundwater, and rainwater that have come into contact with the remnants of the melted reactor core. It contains more than 60 types of radioactive nuclides, including tritium, carbon-14, strontium-90, and iodine-129, many of which lack effective treatment technologies and have extremely long physical half-lives. Carbon-14 has a half-life of 5,730 years and will accumulate in large quantities in marine organisms, potentially reaching concentrations 50 times higher than tritium. Iodine-129 has a half-life of 15.7 million years, and once it enters the marine ecosystem, it will pose a trans-century radiation hazard. Simulation data from the German Institute for Marine Sciences shows that within 57 days of discharge, the radioactive material will spread to a large part of the Pacific Ocean, affecting the United States and Canada within 3 years, and spreading to global waters within 10 years. No coastal country will be able to escape its effects.