An inflatable sheet includes an optical fiber extending across at least a portion of its surface to detect a breach or nuclear radiation. The sheet can line at least a portion of a container or several such sheets can line several walls of the container. A breach of the sheet or radiation within or near the sheet reduces optical transmissibility of the fiber. The fiber integrates the radiation over time and/or over the length and volumetric mass of the fiber, making the fiber sensitive to even low-level radiation. The optical fiber is monitored for a change in its transmissibility. A reduction in the transmissibility, such as to below a threshold, can trigger an alarm, such as an annunciator, a self-destruct circuit or send a message that includes information about the time or the container's contents or location when the breach or radiation is detected to a central location, such as a ship's control room or port notification system.