Radiation Heat Transfer Environment in Fire and Furnace Tests of Radioactive Materials Packages

The Hypothetical Accident Conditions (HAC) sequential tests of radioactive materials (RAM) packages includes a thermal test to confirm the ability of the package to withstand a transportation fire event. The test specified by the regulations (10 CFR 71) consists of a 30 minute, all engulfing, hydrocarbon fuel fire, with an average flame temperature of at least 800 degrees C. The requirements specify an average emissivity for the fire of at least 0.9, which implies an essentially black radiation environment. Alternate tests which provide equivalent total heat input at the 800 degrees C time averaged environmental temperature may also be employed. When alternate tests methods are employed, such as furnace or gaseous fuel fires, the equivalence of the radiation environment may require justification. The effects of furnace and open confinement fire environments are compared with the regulatory fire environment, including the effects of gases resulting from decomposition of package overpack materials. The results indicate that furnace tests can produce the required radiation heat transfer environment, i.e., equivalent to the postulated pool fire. An open enclosure, with transparent (low emissivity) fire does not produce an equivalent radiation environment.