Tellurium-128 and -130 are essentially stable. They only decay by double beta decay, with half lives >10 years. They constitute the major fraction of natural occurring tellurium at 32 and 34% respectively. Tellurium-132 and its daughter I are important in the first few days after a criticality. It was responsible for a large fraction of the dose inflicted on workers at Chernobyl in the first week.