text: Niobium-95, with a half-life of 35 days, is initially present as a fission product. The only stable isotope of niobium has mass number 93, and fission products of mass 93 first decay to long-lived  zirconium-93 (half-life 1.53 Ma). Niobium-95 will decay to molybdenum-95 which is stable.