Burst calculations for Cf-252 brachytherapy sources

Due to helium production following alpha decay, it is necessary to demonstr ate the structural integrity of new Cf-252 sources at elevated temperatures for special form certification by the U.S. Department of Transportation. E ffects of temperature, capsule composition, and capsule dimensions are exam ined and reduced to a simple mathematical model. This highly conservative m odel assumes that all gas products leaving the radioactive source wire are retained by the capsule, and upon elevation to a temperature of 800 degrees C the capsule exhibits negligible expansion or change in internal volume an d no increase in gas-phase components due to vaporization of spontaneous fi ssion products. The calculated maximum loadings for the ORNL-made Applicato r Tube and three proposed high dose rate Cf-252 sources encapsulated in Pt/ Ir-10% (VariSource, microSelectron classic, and a novel design) were 10.8, 0.508, 0.708, and 2.12 mg Cf-252, respectively. (C) 2000 American Associati on of Physicists in Medicine. [S0094-2405(00)01912-X].