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Abstract not provided.

Sandia National Labs has been investigating concepts for high power lasers pumped directly by fission energy. The direct pumping of laser media with fission fragments offers the potential advantages of scaling to high powers and very long run times in a compact, self powered system. To investigate the potential of this concept, extensive experiments have been conducted in the Annular Core Research Reactor (ACRR) and the Sandia Pulsed Reactor (SPR-III). These experiments include laser physics tests, radiation effects tests on optical materials, and experiments to examine the scaling of reactor pumped lasers to high powers. The SPR-III is a U-10%Mo fast burst reactor which is used for laser physics experiments. SPR-III is capable of 70 to 1500 {mu}s FWHM pulses generating up to several kW/cc excitation in a liter size laser cavity. The pulse widths greater than a few hundred microseconds are achieved using a pulse stretcher consisting of gram amounts of fissile material surrounded by moderator. The ACRR is a UO{sub 2}BeO fueled epithermal reactor which is used for larger volume scaling and beam quality experiments. ACRR operates in both steady state and pulsed modes with pulse widths of 7 to 250 ms resulting in excitation rates of {approximately}2 to 100 W/cc in excitation volumes of up to 50 1. Experimental configurations on both reactors have included central cavity and external cavity locations. The experiments on SPR-III have defined optimum conditions for efficient reactor pumping of rare gas lasers. This information has been used to define scaling experiments now in progress in the ACRR.

Four fluorosilica clad, all silica core fibers with polyamide buffers were examined for radiation-induced, transient absorption in the central cavity of the Annular Core Research Reactor. The reactor operated 24 times in the pulse mode, typically yielding gamma doses of 15 krad(Si) and neutron fluences of 1.4 {times}10{sup 14} nts/cm{sup 2} thermal and 1.0 {times} 10{sup 15} nts/cm{sup 2} (fast). The two low-OH fibers absorbed 90% of the light in the 400 to 500 nm region and 30% in the 700 and 800 nm region. The high-OH fibers absorbed 20% in the 400 to 500 nm region and 50% in the 700 to 800 nm region. Saturation of the transient induced absorption was observed in all the fibers. No systematic measurements were taken of long term induced absorption. However, excessive absorption was not a problem in any fibers, even those that received total gamma doses of 5 Mrad(Si). Scintillation in the 680 to 820 mn band was observed. This report documents the data from these experiments.