A containment tube includes a sealed tube comprising silicon carbide, first and second ends, an inner bore extending along at least a portion of its axial length between the first and second ends, and contains a radioactive material within the bore of the sealed tube. The first end has a plug residing in the inner bore to close the first end, and the second end has a distal wall that closes the inner bore at the second. At least one of the first or second ends is bonded to the sealed tube by a sinter bond.