Radioactive temperature indicating devices

Claim 1

A DEVICE FOR POSITIVELY INDICATING WHETHER A CONTAINER-ENCLOSED COMPONENT HAS BEEN PREVIOUSLY SUBJECTED TO CRITICAL TEMPERATURES COMPRISING IN COMBINATION THEREWITH A SHIELD RELEASABLY SUPPORTED WITHIN SAID CONTAINER AND SURROUNDED BY SAID COMPONENT, SAID SHIELD HAVING A RECESS ADJACENT AN UPPER PORTION, A FUSIBLE MATERIAL HAVING A MELTING POINT SUBSTANTIALLY THE SAME AS THE CRITICAL TEMPERATURE OF SAID COMPONENT AND SECURED WITHIN SAID RECESS. SUPPORTING MEANS FIXED TO SAID CONTAINER COOPERATING WITH SAID FUSIBLE MATERIAL WHEN THE TEMPERATURE IS BELOW SAID MELTING POINT, A RADIOACTIVE SOURCE OF RADIATION EXTERNALLY ADJACENT A LOWER PORTION OF SAID CONTAINER, SAID SHIELD BEING IMPERVIOUS TO SAID RADIATION, AND DETECTOR MEANS IN EXTERNALLY OPPOSED DIAMETRICAL RELATION TO SAID RADIOACTIVE SOURCE FOR RECEIVING SAID RADIACTION WHEN SAID RADIATION IS NOT INTERRUPTED BY SAID SHIELD, WHEREBY THE RECEPTION OF RADIATION BY SAID DETECTOR INDICATES THAT THE DEVICE HAD NOT BEEN EXPOSED TO A CRITICAL TEMPERATURE, AND THE ABSENCE OF RECEPTION OF RADIATION INDICATES THAT THE DEVICE HAS BEEN EXPOSED TO A CRITICAL TEMPERATURE WHICH CAUSED SAID FUSIBLE MATERIAL TO MELT AND ALLOW SAID SHIELD TO SEPARATE FROM ITS SUPPORT AND FALL INTO A POSITION BETWEEN SAID RADIOACTIVE SOURCE AND SAID DETECTOR.