Abstract: A carousel and first and second members have common axes in a first direction. The carousel, preferably cylindrical, has a ring-shaped configuration defined by inner and outer diameters. The first member has an outer diameter preferably contiguous to the carousel inner diameter. The second member has an inner diameter preferably contiguous to the carousel outer diameter. The carousel is divided into compartments by vanes. The carousel rotates at a substantially constant speed past radiation directed by an accelerator in the first direction. When a fault occurs in the system operation, (1) the carousel and radiation stop and (2) the carousel reverses in direction. When the fault is resolved, the carousel moves in the forward direction at the substantially constant speed and the radiation resumes at the position where the article was being irradiated at the time that the fault occurred.