It should be noted that KC8 can be used in the place of the Al/Hg amalgam, but as we discussed above, over reduction can occur rendering these reactions unpredictable. When this takes place, the californium becomes intercalated into the graphite and is difficult to extract. Given the scarcity of 249 Cf, the herculean efforts required to recycle it, and the real external radiation hazards that it poses to researchers even on small scales (ca. 5 mg), it is ill advised to utilize these overly strong reductants to prepare Cf II .