This specification covers the properties and requirements for pellets of stabilized cubic hafnium oxide used in nuclear reactors. Hafnium oxide should consist of a stabilizing agent, the recommended of which is yttrium oxide, though others such as calcium oxide and magnesium oxide may also be used as agreed upon by the buyer and seller. The material shall meet specified values of the following requirements: physical dimensions; density; mechanical properties; phase stabilization; impurity concentration limits; moisture concentration limit; visual appearance; end and circumferential chips; cracks; and fissures and other defects.