PuO2

PuO2, or plutonium dioxide, is a radioactive ceramic oxide of plutonium with the formula PuO2. It is a dense, refractory solid that serves as a principal feedstock and fuel material in nuclear technology. PuO2 is most commonly used in nuclear fuel applications, particularly as the oxide form of plutonium in mixed oxide fuel (MOX) and as a precursor for plutonium-based fuel cycles.

Structurally, PuO2 adopts the fluorite-type structure (CaF2-type). It is typically prepared as stoichiometric PuO2, though under oxidizing conditions it can form non-stoichiometric oxides such as PuO2+x. It has a very high melting point (approximately 2350–2380 C) and a high density near 11.6 g/cm3. PuO2 is chemically robust, relatively insoluble in water, and forms a solid ceramic material with moderate thermal conductivity. It is primarily an alpha emitter, with radiological hazards that require special handling and shielding.

Production of PuO2 generally involves calcination of plutonium precursors, such as Pu(IV) nitrate, oxalate, or other oxide forms, in air to yield high-purity PuO2. It can also be produced by oxidation of plutonium metal at high temperatures. The oxide is then used directly or blended with uranium dioxide (UO2) to form MOX fuel, which is fabricated into ceramic pellets for use in nuclear reactors.

Safety and regulatory considerations are central to PuO2 handling. The material is highly radiotoxic, generates heat through radioactive decay, and requires containment, remote handling, shielding, and strict safeguards to prevent release and limit criticality risks.