| Popis: |
The CO content of irradiated (Th, U)O 2 kerneled HTR fuel particles has been measured by mass spectrometry. An evaluation of all the data thus obtained showed that the oxygen release, O/f (atoms per fission), during irradiation is governed by thermodynamic equilibrium; O/f is a function of the irradiation temperature T (K), the initial Th/U-235 ratio N , and the burnup F (fissions per initial heavy metal atom). Within the limits of 1073 , 4 , and 0.04 , the oxygen release can be represented by the expression log 10 O/f = 0.96 − 4420/T + 0.4 log 10 N + 0.3 log 10 F . The attainment of equilibrium proceeds rather slowly; at 1473 K it takes about 130 h to reach 99% of the equilibrium value. Coated particles which had undergone large fission-product losses showed significantly increased oxygen release values. |
