Proliferation Resistant Plutonium and Uranium by way of Decay Heat

Obtaining proliferation resistant plutonium and uranium can have major impacts on nuclear nonproliferation and international safeguards. Two key isotopes, 238Pu and 232U, can be used to increase the proliferation resistance of plutonium and uranium samples respectively. Since 238Pu has a large alpha decay heat, increasing the isotopic content of 238Pu in plutonium can increase the heat generation andmake the plutonium sample less attractive and possibly useless for weapons purposes. Utilizing a plutonium vector resulting from very high burn-up, the temperature profiles within three hypothetical nuclear explosive devices are calculated. From these temperature profiles, the maximum temperature within the high explosives is determined and compared to the temperature required for self-explosion. This result sets a limit at which the percentage of 238Pu renders the material useless for a weapon. Currently, the limit of 238Pu in plutonium above which the plutonium is exempt from safeguards is 80% 238Pu. Reducing this percentage would lead to less plutonium material under safeguards, thus saving money that can be used elsewhere. Similarly, 232U’s high alpha decay heat is used to generate heat in a hypothetical nuclear weapon. The temperature profile is calculated and the maximum temperature in the high explosives is determined. This temperature is compared with the self-explosion temperature. Setting a limit for 232U content could reduce the amount of material needed to be under safeguards. As in the case of plutonium, this too would save money and increase the difficulty of using material with this amount of 232U for weapons purposes.