Patent ID: 8374311

Claim:
A method of determining whether a stack of pellets in a thermal battery are in a desired order, the stack of pellets including at least one first type of pellet and at least one second type of pellet, the method comprising: irradiating the first type of pellet in the thermal battery with an incident energy beam, wherein the first type of pellet emits radiation in response to being irradiated with the energy beam; detecting the radiation emissions from the irradiated first type of pellet with a radiation detector; irradiating the second type of pellet in the thermal battery with an incident energy beam, wherein the second type of pellet emits radiation in response to being irradiated with the energy beam; detecting the radiation emissions from the irradiated second type of pellet with a radiation detector; analyzing the detected radiation emissions from the first type of pellet and the second type of pellet to determine whether the first and second types of pellets in the thermal battery are stacked in the desired order.