Isotopes of selenium

Selenium-79 is a radioisotope of selenium present in spent nuclear fuel and the wastes resulting from reprocessing this fuel. It is one of only seven long-lived fission products. Its fission yield is low (about 0.04%), as it is near the lower end of the mass range for fission products. Its half-life has been variously reported as 650,000 years, 65,000 years, 1.13 million years, 480,000 years, 295,000 years, 377,000 years, and most recently and the best current value, 327,000 years.