milligrams of natural boron per centimeter of pellet length the corresponding quantity of cadmium 113 isotope is 11 0 milligrams of natural cadmium per centimeter of pellet length when cadmium 113 isotope is substituted for the boron 10 isotope such substitution would for example be approximately in the ratio of 11 parts by weight of cadmium to 3 2 parts by weight of boron this substitution of the oxide of cadmium 113 isotope for the boron 10 isotope increases the rate of burnout of the burnable absorber reduces the amount of undesirable gases produced by the burnout of the boron and produces a harder and more refractory glaze coating in this regard the cadmium 113 isotope produces no gaseous products as a result of neutron capture thus the use of the oxide of cadmium 113 isotope as a burnable absorber burns out more rapidly than the boron 10 isotope and leaves less residual burnable absorber at any given time than that of the boron 10 isotope referring again to the sole figure a typical nuclear reactor pellet 100 of fissionable material such as enriched uranium dioxide or mixed oxides might be of the order of 0 5 inches 1 3 centimeters in length the nuclear fuel pellet 100 is expected to have a cadmium silicate glaze coating containing about 16 milligrams of the oxide of.