If you want to have any stockpiles of radioactive materials locked up, buy one of those el cheapo safes from IKEA. Any one that has external hinges. Buy some thick cork gasket paper, and line the edges (which are made of 2mm steel sheet, but bended to make edges about half an inch wide). Seal up any cracks with sillycone. Then buy some RadMax radiation sheilding, and solder a few sheets onto the outside (leaving an uncovered area for the lock). Problem solved. That is, if you're keeping aerosol-prone radium salts.