[en] An experiment was conducted in DIII-D to examine carbon deposition when a secondary separatrix is near the wall. The magnetic configuration for this experiment was a biased double-null, similar to that foreseen for ITER. ¹³C methane was injected toroidally symmetrically near the secondary separatrix into ELMy H-mode deuterium plasmas. The resulting deposition of ¹³C was determined by nuclear reaction analysis. These results show that very little of the injected ¹³C was deposited at the primary separatrix, whereas a large fraction of injected ¹³C was deposited close to the point of injection near the secondary separatrix. Six of the tiles were put back into DIII-D, where they were baked at 350-360 °C for 2 h at ∼1 kPa in a 20% O₂/80% He gas mixture. Subsequent ion beam analysis of these tiles showed that about 21% of the ¹³C and 54% of the deuterium were removed by the bake.