Dependence of porosity of alumino-silicate coatings on firing conditions

In order to retain the fission fragments ejected from the cutter layer of the vitroceramic nuclear fuel, the porosity of alumino-silicate coating applied on fuel elements must be so low lest the fraction of the defected area should exceed 5x10-7. Here it is reported how the coating porosity depends on the firing conditions. Thus, the porosity of coatings fired up to their melting temperatures is too high, and its value could not be decreased by performing the thermal treatment in vacuum. Instead, the defected area of same sintered coatings is close to the above mentioned value. (author)