[en] The Cobalt-60 (Co-60) spent sealed radiation source which was previously used in medical for cancer treatment, caused the radiological accident at Soi Wat Mahawong, Samutprakarn Province on 18-20 February 2001. It was successfully retrieved on 20 February 2001 by the retrieval team from Office of Atoms for Peace (OAP) and was kept safely in lead container under water 4.5 meter depth in the spent fuel pool at OAP. For radiation safety in interim storage and final disposal, it was recommended by International Atomic Energy Agency (IAEA) to keep the source in a special design lead container in dry storage and the radiation dose after shielding should be within IAEA safety limit. Therefore, this Co-60 source must be conditioned in the proper container. The conditioning process comprised the manufacturing of a new lead container under the IAEA shielding design standards, the Co-60 leak test, loading of Co-60 to the new lead container under water 4.5 meter depth, the radiation dose measurement after loading, the radioactive contamination monitoring and the transferring of the new Co-60 lead container to the OAP interim dry storage. The results found that there was no leak of Co-60 to the water in spent fuel pool. The US NRC contamination limit of Co-60 in water was <3x10^-3 μCi/L. The new lead container could shield radiation within IAEA radiation safety limit (surface dose rate <2 mSv/hr). After Co-60 loading, the surface/1 meter radiation dose rate on the side and the shield cover were 1.50 mSv/hr/0.08 mSv/hr and 1.40 mSv/hr/0.07 mSv/hr, respectively. There were no radioactive contamination on the container. The new Co-60 lead container was safely transferred and kept at interim dry storage No. 1, radioactive waste management program, OAP