The effect of gamma-ray transport on afterheat calculations for accident analysis

Radioactive afterheat is an important source term for the release of radion uclides infusion systems under accident conditions. Heat transfer calculati ons are used to determine time-temperature histories in regions of interest , but the true source term needs to be the "effective afterheat, " which co nsiders the transport of penetrating gamma rays. Without consideration of p hoton transport, accident temperatures may be overestimated in some regions while being underestimated in others. The importance of this effect is dem onstrated for a simple, one-dimensional problem. The significance of this e ffect depends strongly on the accident scenario being analyzed.