A compactness property for solutions of the Ricci flow on orbifolds

In this paper we consider Ricci flow on orbifolds with at most isolated singularities. We generalize two results of R. Hamilton to orbifolds. The first result is the compactness property of Ricci flow and the second is an injectivity radius estimate for Ricci flow. In the proof of the compactness property we give an orbifold version of the injectivity radius estimate of J. Cheeger, M. Gromov and M. Taylor. Also along the way we prove a compactness property of Riemannian orbifolds.