TAM] 3 Principal Fission Produete a. Half-life - Nuclide Fission yield from fission of “35U by thermal neutrons Strontium-89 Strontium-90 50.4 days | 28 years Yttriu-91 58.0 days - Zirconium-95 63.3 days Ruthenium-103 °°, 41.0 days Tellurium-129m 33.0 days - Promethium-147 6.3 Niobium-95 35 days 0.4 Rhodium-106 30 seconiis Bériun-137m 2.6 minutes 6.0 6.0 5.7 2.4 2.52 years of daughter -64.4 hours 0.9 OS 32.5 days 290 days product Half-life -Yttrium-90 3.0 30 years Cesium-137 Cerium-141 Cerium-1h4 | daughter 4.8 5.8 5.8 ~~} 1.0 years Ruthenium-106 ; % Radioactive ae nee rege ES| Ee -- Rhodium-103m -- 54 minuten Tellurium-129 74 minutes 1.6 x 10 Todine-129 years --Praseodymium144 17.5 minutes Neodymium-144.-2.5 x 101? Samarium-147 1.3°x 1011 . years The two major radionuclides with half-lives greater than a year are strontium~-90 and cesium-137. Both are soluble in sea water, and tend to remain in the water, rather than sink to the bottom. they would sink slowly until dissolved. Introduced as fallout particles, Measurements show that most of the strontium-90 and cesium-137 that has fallen on the oceans still resides above » 1. Burton, J. D. "Radioactive Nuclides," Chapter 22, In Chemical Oceanography, Vol. 2, Edited by Riley and Skirrow, Academic Press, N.Y. 1965.