1) You are really asking about the "refractory period", which is quite distinct from the "repolarization time". The absolute refractory period, which is the time after an action potential that a neuron is absolutely unable to fire another
action potential, has a textbook value of 1 msec. Now, this masks a great range`of firing frequencies - 1 kHz is usually considered an absolute upper bound, with 800 Hz or so the highest I've seen in print. (Any counterexamples out there?)
2) Your definition does not accord with the neuronal reality of repolarization.
In short, a neuron need not repolarize to fire another action potential (e.g.
thousands of examples of plateau potentials with burst firing, in both
vertebrate and invertebrate systems).
3) Assuming that you are making neocortical mammalian models, you might
want to look at work from the laboratory of John Connors, among others. There
was a relatively recent TINS review on this subject.
4) If only we could model a single neuron realistically....
Stanford Neuroscience Program
email:mbieda at psych.stanford.edu