Prompt radiations from the reactions 7Li(p, n) and 19F(p, αγ) have been applied to measure concentrations of the target nuclei in graphite using protons from the ORNL 3-MV Van de Graaff accelerator. A sample irradiated nine months in the Molten Salt Reactor Experiment shows over a hundred times the lithium and fluorine penetration found in an unirradiated control sample.