Application of an independent parallel reactions model on the annealing kinetics to irradiated graphite waste

Annealing of ion irradiation damage in nuclear graphite

“…The process of annealing defects can be considered as a phase change reaction, which may be described using kinetic models [21][22][23][24]. Previous graphite annealing models have used data obtained from neutron-irradiated graphite samples.…”

“…The basic relationship that all kinetic approaches use is defined as [21][22][23][24][25][26][27][28]:…”

“…The divergence between calculated and experimental results, can be expressed as a percentage, associated with the largest rate of reaction observed in the experimental curve, of the following type [24,25,27]:…”

“…Minimising the parameter Dev1 is a non-linear optimization problem, and can be solved using a nonlinear optimization algorithm [24,25,26,28] by controlling the activation energy E a , pre-exponential factor A, and order of reaction n; these are the kinetic parameters. The solution is generally considered satisfactory when Dev1 is less than 3% [24,25,26,28]. In this work, the Generalized Reduced Gradient [29] implemented within the Solver Add-in of Microsoft Excel 2003, was utilized.…”

“…DSC experiments provide data on the rate of energy release in a specimen versus temperature or time. Wigner energy [16,[21][22][23][24] is the potential energy of the carbon atoms that have been displaced from their original lattice position by neutron bombardment such as takes place a nuclear reactor. The population of defects Q is proportional to the energy released S.…”