Section 173.442 - Thermal limitationsA package of Class 7 (radioactive) material must be designed, constructed, and loaded so that-
(a) The heat generated within the package by the radioactive contents will not, during conditions normally incident to transport, affect the integrity of the package; and(b) The temperature of the accessible external surfaces of the loaded package will not, assuming still air in the shade at an ambient temperature of 38 °C (100 °F), exceed either- (1) 50 °C (122 °F) in other than an exclusive use shipment; or(2) 85 °C (185 °F) in an exclusive use shipment.